The absence of mirror symmetry, or chirality, is behind striking natural phenomena found in systems as diverse as DNA and crystalline solids. A remarkable example occurs when chiral semimetals with ...topologically protected band degeneracies are illuminated with circularly polarized light. Under the right conditions, the part of the generated photocurrent that switches sign upon reversal of the light's polarization, known as the circular photo-galvanic effect, is predicted to depend only on fundamental constants. The conditions to observe quantization are non-universal, and depend on material parameters and the incident frequency. In this work, we perform terahertz emission spectroscopy with tunable photon energy from 0.2 -1.1 eV in the chiral topological semimetal CoSi. We identify a large longitudinal photocurrent peaked at 0.4 eV reaching ~550 μ A/V
, which is much larger than the photocurrent in any chiral crystal reported in the literature. Using first-principles calculations we establish that the peak originates only from topological band crossings, reaching 3.3 ± 0.3 in units of the quantization constant. Our calculations indicate that the quantized circular photo-galvanic effect is within reach in CoSi upon doping and increase of the hot-carrier lifetime. The large photo-conductivity suggests that topological semimetals could potentially be used as novel mid-infrared detectors.
The local electronic structure of aqueous histidine, an amino acid important in nature and biology, is revealed by aerosol X-ray photoemission spectroscopy. A detailed picture of the photoionization ...dynamics emerges by tuning the pH of the aqueous solution from which the aerosols are generated, allowing us to report the X-ray photoelectron spectroscopy (XPS) of histidine. Assignment of the experimental photoelectron spectra of the C1s and N1s levels allows the determination of the protonation state of histidine in these aqueous aerosols and is confirmed by density functional calculations. XPS spectra show that at pH = 1, both imidazole and amine group nitrogens are protonated, at pH = 7, the amine group nitrogen is protonated and the carboxyl group carbon is deprotonated resulting in a zwitterionic structure, and at pH = 13, only the carboxyl group remains deprotonated. Comparison of these results with previous experimental and theoretical results suggests that X-ray spectroscopy on aqueous aerosols can provide a convenient and simple way of probing their electronic structure in aqueous solutions.
X-Ray spectroscopy coupled with DFT calculations reveals the pH dependent electronic structure of an amino acid in an aqueous environment.
The microstructure and mechanical properties of the CoCrCuFeNiNb high-entropy alloy coating prepared by plasma transferred arc cladding process were investigated. Two phases are found in the prepared ...coating with Nb: one is face-centered-cubic solid solution phase; the other is the Laves phase of (CoCr) Nb type. The nano-indentation testing indicates that the microhardness (H), elastic modulus (E), the hardness/modulus of elasticity ratio (H/E ratio) and high resistance to plastic deformation (H3/E2) of the coating with Nb are 6.13GPa, 221GPa, 0.028 and 4.7×10−3 respectively. The CoCrCuFeNiNb coating displays excellent wear and corrosion resistance. The wear resistance of the coating with Nb is about 1.5 times higher than that of the coating without Nb under the same wet sand rubber wheel abrasion testing conditions. Compared with the coating without Nb and as-cast 304 stainless steel, the coating with Nb shows the lowest icorr values in polarization curves and the highest fitted Rf values in EIS plots in 6N hydrochloric acid solution.
•The CoCrCuFeNiNb HEA coating was prepared by PTA cladding process.•The Nb-free coating was also studied as a comparison material.•Nano-indention was used to investigate mechanical properties of the coating.•The coating has better wear and corrosion resistance than that of Nb-free coating.
Antiferromagnets are interesting materials for spintronics because of their faster dynamics and robustness against perturbations from magnetic fields. Control of the antiferromagnetic order ...constitutes an important step towards applications, but has been limited to bulk materials so far. Here, using spatially resolved second-harmonic generation, we show direct evidence of long-range antiferromagnetic order and Ising-type Néel vector switching in monolayer MnPSe3 with large XY anisotropy. In additional to thermally induced switching, uniaxial strain can rotate the Néel vector, aligning it to a general in-plane direction irrespective of the crystal axes. A change of the universality class of the phase transition in the XY model under uniaxial strain causes this emergence of strain-controlled Ising order in the XY magnet MnPSe3. Our discovery is a further ingredient for compact antiferromagnetic spintronic devices in the two-dimensional limit.Antiferromagnets are interesting materials for fast spintronics applications, but control of the antiferromagnetic order has been limited to bulk materials so far. Now, uniaxial strain is shown to align the Néel vector in MnPSe3 down to the monolayer limit.
Aim
Endothelial cell injury assumes a fundamental part in the pathogenesis of atherosclerosis, and endothelial cell autophagy has protective effects on the development of atherosclerosis, although ...the underlying molecular regulation mechanism is indistinct. This study aimed to investigate whether microRNA‐214‐3p (miR‐214‐3p) is involved in the endothelial cell autophagy regulation of atherosclerosis.
Methods
We utilized ApoE−/− mice provided with a high‐fat diet (HFD) as atherosclerosis model. We analysed the level of miR‐214‐3p and the levels of autophagy‐related protein 5 (ATG5) and autophagy‐related protein 12 (ATG12) in the purified CD31+ endothelial cells from mouse aorta. Bioinformatics analysis and a dual‐luciferase reporter assay were performed to confirm the binding target of miR‐214‐3p. In vitro study, human umbilical vein endothelial cells (HUVECs) were transfected with miR‐214‐3p mimics/inhibitor and stimulated with 100 μg/mL oxidized low‐density lipoprotein (ox‐LDL) for 12 hours to initiate a stress‐repairing autophagic process.
Results
In mouse models, we identified an inverse correlation between miR‐214‐3p, ATG5 and ATG12. We observed that in young HUVECs, ox‐LDL‐initiated autophagy was repressed by miR‐214‐3p overexpression, as evaluated by autophagic protein analysis, microtubule‐associated protein 1 light chain 3B‐II (LC3B‐II) immunofluorescence assay and transmission electron microscopy (TEM). Also, miR‐214‐3p promoted ox‐LDL accumulation in HUVECs and THP‐1 monocyte adhesion. Conversely, in old HUVECs, suppression of miR‐214‐3p preserved the ability to initiate a protective autophagy reaction to the ox‐LDL stimulation.
Conclusion
miR‐214‐3p regulates ox‐LDL‐initiated autophagy in HUVECs by directly targeting the 3′UTR of ATG5 and may have a suitable role in the pathogenesis of atherosclerosis.
Phase separation is a cooperative process, the kinetics of which underpin the orderly morphogenesis of domain patterns on mesoscopic scales
. Systems of highly degenerate frozen states may exhibit ...the rare and counterintuitive inverse-symmetry-breaking phenomenon
. Proposed a century ago
, inverse transitions have been found experimentally in disparate materials, ranging from polymeric and colloidal compounds to high-transition-temperature superconductors, proteins, ultrathin magnetic films, liquid crystals and metallic alloys
, with the notable exception of ferroelectric oxides, despite extensive theoretical and experimental work on the latter. Here we show that following a subcritical quench, the non-equilibrium self-assembly of ferroelectric domains in ultrathin films of Pb(Zr
Ti
)O
results in a maze, or labyrinthine pattern, featuring meandering stripe domains. Furthermore, upon increasing the temperature, this highly degenerate labyrinthine phase undergoes an inverse transition whereby it transforms into the less-symmetric parallel-stripe domain structure, before the onset of paraelectricity at higher temperatures. We find that this phase sequence can be ascribed to an enhanced entropic contribution of domain walls, and that domain straightening and coarsening is predominantly driven by the relaxation and diffusion of topological defects. Computational modelling and experimental observation of the inverse dipolar transition in BiFeO
suggest the universality of the phenomenon in ferroelectric oxides. The multitude of self-patterned states and the various topological defects that they embody may be used beyond current domain and domain-wall-based
technologies by enabling fundamentally new design principles and topologically enhanced functionalities within ferroelectric films.
Recent advancements in electronics engineering require materials with the resiliency and sustainability to extend their life time. With this regard, we presented a sustainable multi-functional ...nanocomposites strategy by introducing dynamic imine bonds based polyazomethine (PAM) as molecular interconnects and Fe3O4-loaded multiwalled carbon nanotubes as electromagnetic (EM) wave absorbing units. Driven by the reversible dynamic imine bonds, our materials show robust spontaneous self-healing with excellent healing efficiencies of 95% for PAM and 90% for nanocomposite, and an accelerated recovery under a moderate mechanical stimulus. By adding Fe3O4-loaded multiwalled carbon nanotubes, the hybrids show excellent EM wave absorbing properties with 50% increment on minimum reflection coefficient (−40.6 dB) than the reported value. We demonstrate a full degradability by decomposing a nanocomposite sheet of 100 mg in an acidic solution within 90 min at room temperature. The nanofillers and monomers after degradation can be re-used to synthesis nanocomposites. The testing results for recoverable nanocomposites show a good retention on mechanical property. This novel strategy may shed a light on the downstream applications in EM wave absorbing devices and smart structures with great potential to accelerate circular economy.
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Mixed cobalt and manganese oxides embedded in the nanoporous carbon framework (M/MO@C) were synthesized by the direct carbonization of a binary mixed-metal organic framework (CoMn-MOF-74) for the ...first time. The unique M/MO@C carbon materials maintained the primary morphology of CoMn-MOF-74, and showed a uniform dispersibility of Co, MnO and CoO nanoparticles in the carbon matrix, and therefore greatly increased the conductivity of the M/MO@C materials. A series of M/MO@C samples were tested as the electrode materials for supercapacitors, and a remarkable specific capacitance of 800 F g
−1
was obtained using the M/MO@C-700 sample at a current density of 1 A g
−1
in 6 M KOH electrolyte. Moreover, the M/MO@C sample showed a good cycling stability with a capacitance retention of 85% after 1000 cycles. It is also found that the optimized carbonization temperature is a critical parameter to obtain such a M/MO@C nanoporous carbon framework with the best capacitive performances. The present approach is convenient and reproducible, which could be easily extended to the preparation of other M/MO@C composites with excellent electrochemical performances.
A remarkable specific capacitance of 800 F g
−1
was obtained using cobalt and manganese oxides in a carbon framework derived from CoMn-MOF-74; carbonization temperature is a critical parameter.
The objective of this study was to investigate how 6 commonly used solvent systems affected the yields of phenolic substances and the antioxidant capacity of extracts from 8 major classes of food ...legumes. Several antioxidant-related phytochemical compositions, namely, total phenolic content (TPC), total flavonoids content (TFC), and condensed tannins content (CTC), were investigated. In addition, antioxidant activities were tested using 2,2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging, ferric-reducing antioxidant power (FRAP), and the oxygen radical absorbance capacity (ORAC). The results showed that the 50% acetone extracts exhibited the highest TPC for yellow pea, green pea, chickpea, and yellow soybean. Acidic 70% acetone (+0.5% acetic acid) extracts exhibited the highest TPC, TFC, and FRAP values for black bean, lentil, black soybean, and red kidney bean. The 80% acetone extracts exhibited the highest TFC, CTC, and DPPH-free radical scavenging activity for yellow pea, green pea, chickpea, and yellow soybean. The 70% ethanol extracts exhibited the greatest ORAC value for all selected legumes. These results indicated that solvents with different polarity had significant effects on total phenolic contents, extracted components, and antioxidant activities. High correlations between phenolic compositions and antioxidant activities of legume extracts were observed. The information is of interest to the nutraceutical food/ingredient industries since legumes are a rich source of antioxidants.