Highlights
NiCo-LDHs successfully grow in situ on rod-like ZnO with unique structures.
The interface of NiCo@C and rod-like ZnO result in interfacial polarization.
The RLmin of NiCo@C/ZnO reaches − ...60.97 dB with the EABmax of 6.08 GHz.
The excellent performance comes from the effect of dielectric loss and magnetic loss.
Layered double hydroxides (LDHs) have a special structure and atom composition, which are expected to be an excellent electromagnetic wave (EMW) absorber. However, it is still a problem that obtaining excellent EMW-absorbing materials from LDHs. Herein, we designed heterostructure NiCo-LDHs@ZnO nanorod and then subsequent heat treating to derive NiCo@C/ZnO composites. Finally, with the synergy of excellent dielectric loss and magnetic loss, an outstanding absorption performance could be achieved with the reflection loss of − 60.97 dB at the matching thickness of 2.3 mm, and the widest absorption bandwidth of 6.08 GHz was realized at 2.0 mm. Moreover, this research work provides a reference for the development and utilization of LDHs materials in the field of microwave absorption materials and can also provide ideas for the design of layered structural absorbers.
•The effect of temperature on inhibition efficiency was investigated by experiments.•The interaction between SCMC and calcite was explored by MD.•The scale inhibition efficiency increases with the ...solution temperature.•The highest scale inhibition efficiency at 96.2% at 323 K.•The computational results agree with the anti-scaling experimental phenomena.
Sodium carboxymethyl cellulose (SCMC) is one of the most promising scale inhibitors. In this study, the performance of SCMC in inhibiting the deposition of calcium carbonate on heat transfer surface at the temperatures ranging from 293 to 343 K was investigated by experiments, and the interaction between SCMC and calcite in the solution was explored by molecular dynamics simulation. The experimental results showed that the fouling resistance substantially decreases by adding the SCMC. The scale inhibition efficiency increases with the solution temperature, and the highest scale inhibition efficiency at 99.8% at 343 K. The simulated results showed that with the increase of the solution temperature, both the binding energy between SCMC and calcite plane and the probability of SCMC binding with calcium ions increase, which can effectively prevent the growth of calcium carbonate fouling on the heat transfer surface. Therefore, our computational results agree with the anti-scaling experimental phenomena.
A new kind of chiral zirconium based metal-organic framework, l-Cys-PCN-222, was synthesized using l-cysteine (l-Cys) as a chiral modifier by a solvent-assisted ligand incorporation approach and ...utilized as the chiral stationary phase in the capillary electrochromatography system. l-Cys-PCN-222 was characterized by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, Fourier-transform infrared spectra, nitrogen adsorption/desorption, circular dichroism spectrum, zeta-potential and so on. The results revealed that l-Cys-PCN-222 had the advantages of good crystallinity, high specific surface area (1818 m
g
), thermal stability and chiral recognition performance. Meanwhile, the l-Cys-PCN-222-bonded open-tubular column was prepared using l-Cys-PCN-222 particles as the solid phase by 'thiol-ene' click chemistry reaction and characterized by scanning electron microscopy, which proved the successful bonding of l-Cys-PCN-222 to the column inner wall. Finally, the stability, reproducibility and chiral separation performance of the l-Cys-PCN-222-bonded OT column were measured. Relative standard deviations (RSD) of the column efficiencies for run-to-run, day-to-day, column-to-column and runs were 1.39-6.62%, and did not obviously change after 200 runs. The enantiomeric separation of 17 kinds of chiral compounds including acidic, neutral and basic amino acids, imidazolinone and aryloxyphenoxypropionic pesticides, and fluoroquinolones were achieved in the l-Cys-PCN-222-bonded OT column. These results demonstrated that the chiral separation system of the chiral metal-organic frameworks (CMOFs) coupled with capillary electrochromatography has good application prospects.
Epigenetics in Congenital Heart Disease Wang, Guanglei; Wang, Bingbing; Yang, Peixin
Journal of the American Heart Association,
04/2022, Letnik:
11, Številka:
7
Journal Article
Recenzirano
Odprti dostop
Embryonic heart development is an intricate process that mainly involves morphogens, transcription factors, and cardiac genes. The precise spatiotemporal expression of these genes during different ...developmental stages underlies normal heart development. Thus, mutation or aberrant expression of these genes may lead to congenital heart disease (CHD). However, evidence demonstrates that the mutation of genes accounts for only a small portion of CHD cases, whereas the aberrant expression regulated by epigenetic modification plays a predominant role in the pathogenesis of CHD. In this review, we provide essential knowledge on the aberrant epigenetic modification involved in the pathogenesis of CHD. Then, we discuss recent advances in the identification of novel epigenetic biomarkers. Last, we highlight the epigenetic roles in some adverse intrauterine environment-related CHD, which may help the prevention, diagnosis, and treatment of these kinds of CHD.
Exploring cost‐effective and efficient metal‐free electrocatalysts for the oxygen reduction reaction (ORR) is crucial for the development of energy conversion and storage technologies. Reported here ...is a novel heterocyclization strategy to construct efficient ORR catalysts based on linear conjugated polymers (LCPs), which are composed of N‐, S‐, or Se‐heterocycles. Among these polymers, the covalently linked pyridine and thiophene molecule (P‐T) with reduced graphene oxide (rGO) exhibits a remarkable half‐wave potential of 0.79 V (vs. RHE) and excellent electrochemical stability, which are among the highest values for metal‐free polymers as ORR catalysts. Density‐functional theory (DFT) calculations reveal that the molecule with a phenyl unit (P‐Ph) is catalytically inactive, and when a thiophene unit is introduced to replace the phenyl unit in the conjugated backbone it features highly efficient electrocatalytic active sites. More importantly, the well‐defined molecular structures and controllable active sites in the pyrolysis and metal‐free polymers highlight new opportunities for the catalytic metal‐free ORR.
Alterations: Metal‐free linear conjugated polymer (LCP) catalysts were developed using N‐, S‐, or Se‐heterocycles with well‐defined molecular structures. The LCPs possess good solubility, strong dipole interactions, and tunable local atoms, which can alter the spin density and charge distributions of the conjugated structures, leading to tunable active sites and good oxygen reduction reaction (ORR) activity.
Heterogeneous ice nucleation plays important roles in cirrus and mixed‐phase cloud formation, but the efficiency of organic particles to act as ice nuclei (IN) is still not well understood. ...Furthermore, the effect of particle oxidation by O3 on corresponding IN efficiencies has not yet been sufficiently assessed. We present heterogeneous ice nucleation on kaolinite, Suwannee River standard fulvic acid (SRFA), and leonardite standard humic acid particles as a function of particle temperature (Tp), relative humidity with respect to ice (RHice), nucleation mode, and O3 exposure. Ice nucleation and water uptake were studied for Tp >203 K and RHice up to water saturation using a novel ice nucleation apparatus. This study shows that SRFA, leonardite, and corresponding O3‐exposed particles can nucleate ice via different modes at relevant atmospheric conditions. These particles nucleated ice via deposition mode at Tp ≤ 231 K, and for higher Tp water was taken up or ice was nucleated via deposition or immersion mode. Oxidation of leonardite and SRFA particles by O3 led to a decrease in deposition nucleation efficiency and to water uptake at lower temperatures for the former and to an increase in the lowest temperature at which deposition nucleation was observed for the latter. Activated IN fractions and heterogeneous ice nucleation rate coefficients (Jhet) were derived, and corresponding contact angles (θ) were calculated. A parameterization of θ as a function of RHice is presented which allows derivation of Jhet for various deposition IN and corresponding ice crystal production rates for application in cloud‐resolving models.
Various wireless devices have been widely used in every aspect of life and further lead to the severe electromagnetic waves pollution. Fortunately, researchers have developed microwave absorbing ...materials which are able to transfer the harmful electromagnetic waves into other energy, such as thermal energy. In recent years, numerous studies on preparing microwave absorbing materials with various components, morphologies and structures have been reported. Metal oxide-related composites are widely used as microwave absorbers due to their excellent electromagnetic properties. The morphology and nanostructure would play a key role on the microwave absorbing performances, which can cause “structural effect”. The ideal microwave absorbing materials should meet following demands: widely effective absorption frequency (
f
E
), thinner thickness (
d
), light-weight, and strong absorption. In this review, we summarized various common morphologies and structures of metal oxide/metal oxide-based composites, and categorized them from a dimensional perspective. The different microwave absorbing properties and mechanisms are given much attention in detail.
Atmospheric aging of naturally emitted marine aerosol often leads to formation of internally mixed particles composed of sea salts and water-soluble organic compounds of anthropogenic origin. Mixing ...of sea salt and organic components has profound effects on the evolving chemical composition and hygroscopic properties of the resulted particles, which are poorly understood. Here, we have studied chemical composition and hygroscopic properties of laboratory generated NaCl particles mixed with malonic acid (MA) and glutaric acid (GA) at different molar ratios using micro-FTIR spectroscopy, atomic force microscopy, and X-ray elemental microanalysis. Hygroscopic properties of internally mixed NaCl and organic acid particles were distinctly different from pure components and varied significantly with the type and amount of organic compound present. Experimental results were in a good agreement with the AIM modeling calculations of gas/liquid/solid partitioning in studied systems. X-ray elemental microanalysis of particles showed that Cl/Na ratio decreased with increasing organic acid component in the particles with MA yielding lower ratios relative to GA. We attribute the depletion of chloride to the formation of sodium malonate and sodium glutarate salts resulted by HCl evaporation from dehydrating particles.
The performance of devices fabricated from piezoelectric semiconductors, such as sensors and actuators in microelectromechanical systems, is superior; furthermore, plate structures are the core ...components of these smart devices. It is thus important to analyze the electromechanical coupling properties of piezoelectric semiconductor nanoplates. We established a nanoplate model for the piezoelectric semiconductor plate structure by extending the first-order shear deformation theory. The flexural vibrations of nanoplates subjected to a transversely time-harmonic force were investigated. The vibrational modes and natural frequencies were obtained by using the matrix eigenvalue solver in COMSOL Multiphysics 5.3a, and the convergence analysis was carried out to guarantee accurate results. In numerical cases, the tuning effect of the initial electron concentration on mechanics and electric properties is deeply discussed. The numerical results show that the initial electron concentration greatly affects the natural frequency and electromechanical fields of piezoelectric semiconductors, and a high initial electron concentration can reduce the electromechanical fields and the stiffness of piezoelectric semiconductors due to the electron screening effect. We analyzed the flexural vibration of typical piezoelectric semiconductor plate structures, which provide theoretical guidance for the development of new piezotronic devices.
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