A nearly equal molar ratio AlCrMoNbZr high-entropy alloy (HEA) coating was deposited on N36 zirconium alloy substrates using magnetron co-sputtering technology to enhance the corrosion resistance of ...light water reactor (LWR) fuel cladding. The microstructure, mechanical properties, surface wettability and corrosion resistance of the AlCrMoNbZr coating were systematically investigated. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses showed that the AlCrMoNbZr HEA coating contained a composite of amorphous and bcc-structured nanocrystals. A nanoindentation test revealed that the coating had a high hardness of 11.8 GPa, and a scratch test indicated that the coating well adhered to the N36 substrate. The contact angle test showed that the static contact angle was 109°, which indicated the good hydrophobic property of the coating. The corrosion measurement showed that the AlCrMoNbZr coating remained effective after it was immersed in static pure water at 360 °C and 18.7 MPa for 30 days, and no N36 substrate oxides formed, which indicated a superior corrosion resistance. Furthermore, the corrosion behaviour of the coating was discussed. The weight gain measurement (8.8 mg/dm2 weight gain) proved that the coating experienced an oxidation process, and during the process, protective Nb2Zr6O17, ZrO2 and Cr2O3 formed on the surface of the coating. Hence, the AlCrMoNbZr HEA coating is a potential candidate material for accident-tolerant fuel (ATF) coatings.
•AlCrMoNbZr high entropy alloy coating used for accident-tolerant fuel was prepared.•The microstructure and properties of the AlCrMoNbZr coating were systematically investigated.•The AlCrMoNbZr HEA coating exhibits superior corrosion resistance.
p-Type surface conductivity is a uniquely important property of hydrogen-terminated diamond surfaces. In this work, we report similar surface-dominated electrical properties in silicon nanowires ...(SiNWs). Significantly, we demonstrate tunable and reversible transition of p+−p−i−n−n+ conductance in nominally intrinsic SiNWs via changing surface conditions, in sharp contrast to the only p-type conduction observed on diamond surfaces. On the basis of Si band energies and the electrochemical potentials of the ambient (pH value)-determined adsorbed aqueous layer, we propose an electron-transfer-dominated surface doping model, which can satisfactorily explain both diamond and silicon surface conductivity. The totality of our observations suggests that nanomaterials can be described as a core−shell structure due to their large surface-to-volume ratio. Consequently, controlling the surface or shell in the core−shell model represents a universal way to tune the properties of nanostructures, such as via surface-transfer doping, and is crucial for the development of nanostructure-based devices.
•Novel Fe-La-B-based glass forming alloys with good magnetocaloric response near the ambient temperature were achieved in this work;•The GFA and MCE of the Fe88La7B5 glass forming alloy were ...significantly improved by 2% (at. %) addition of Ce;•The Fe86La7B5Ce2 amorphous ribbon show almost the highest magnetic entropy change near 313 K among the Fe-based metallic glasses.
Novel Fe-La-B-based glass forming alloys with better magnetocaloric response near the ambient temperature were achieved in this work. We firstly prepared the Fe88La7B5 glassy alloy with a Curie temperature (Tc) of about 329 K. However, the formability of the ternary metallic glass is very poor and the magnetic measurement on the Fe88La7B5 glassy ribbon indicates that the ribbon may be not fully amorphous. By adding 2% (at. %) Ce, we successfully fabricated Fe86La7B5Ce2 amorphous ribbon with enhanced glass formability, decreased Tc (∼313 K) and better magnetocaloric effect. The magnetocaloric behaviors of the quaternary glassy ribbon were studied and the (ΔTad) was obtained. The high values of magnetic entropy change and adiabatic temperature rise near 313 K indicate that the Fe86La7B5Ce2 metallic glass can be used as an optimal magnetic refrigerant component working at the hot end of a domestic refrigerator.
A defected ground structure (DGS) is used to suppress mutual coupling between elements in a microstrip array and eliminate the scan blindness in an infinite phased array. Two kinds of DGSs, namely ...back-to-back U-shaped and dumbbell-shaped DGSs, are analysed and compared. The analysis indicates that the back-to-back U-shaped DGS is better at suppressing propagation of surface waves in microstrip substrate. A two-element microstrip array with back-to-back U-shaped DGS is designed and the array characteristics against different element distances are studied. The results show that the degree of the mutual coupling suppression is increased when the element distance is reduced. However, compared with the traditional array, a higher gain and lower side lobes are obtained when a larger element spacing is selected. The scan blindness of an infinite microstrip phased array in E-plane is studied by simulation, and the calculation demonstrates that the scan blindness can be eliminated by applying a back-to-back U-shaped DGS to the infinite phased array.
Manipulation of the energy profile of a chemical reaction plays a crucial role in modulating its progress and selectivities. Porphodimethene and phlorin are two key isoelectronic intermediates during ...the stepwise oxidation process leading to the formation of porphyrin from calix4pyrrole. We report here the mechanical capture of porphodimethene instead of phlorin as well as its simultaneous derivatization by means of molecular-strain engineering (MSE). By tuning the linker between its 5- and 15-meso-positions, a constrained porphodimethene has been trapped which can be oxidized with 4,5-dichloro-3,6-dioxo-1,2-benzenedinitrile in the presence of a range of nucleophiles to afford a novel class of stable disubstituted porphodimethene derivatives. Their structures were characterized by NMR spectroscopies, mass spectrometry, and single-crystal X-ray crystallography. Theoretical calculations indicate that the enhanced strain energy resulted from the elongation of the bow-limb in the proposed porphyrin bow favors the formation of the configuration of the porphodimethene intermediate containing two sp3-hybridized meso-carbons rather than that of the phlorin consisting of one sp3-meso-carbon atom. This work demonstrates that MSE can steer the reaction trajectory through specific intermediates, providing the ability to control precisely the reaction progress and selectivity of desired products.
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•Selective trapping the porphodimethene intermediate without multistep synthesis or harsh reaction conditions.•Mechanical trapping of intermediates affords an alternative to conventional adding scavengers for investigating reaction mechanisms.•Reaction selectivity can be controlled by steering the reaction trajectory through specific intermediates.•In situ oxidation of porphodimethene in the presence of H2O and alcohols yields a series of novel disubstituted derivatives.
The analysis of albumin has clinical significance in diagnostic tests and obvious value to research studies on the albumin-mediated drug delivery and therapeutics. The present immunoassay, ...instrumental techniques, and colorimetric methods for albumin detection are either expensive, troublesome, or insensitive. Herein, a class of water-soluble tetrazolate-functionalized derivatives with aggregation-induced emission (AIE) characteristics is introduced as novel fluorescent probes for albumin detection. They can be selectively lighted up by site-specific binding with albumin. The resulting albumin fluorescent assay exhibits a low detection limit (0.21 nM), high robustness in aqueous buffer (pH = 6–9), and a broad tunable linear dynamic range (0.02–3000 mg/L) for quantification. The tetrazolate functionality endows the probes with a superior water solubility (>0.01 M) and a high binding affinity to albumin (K D = 0.25 μM). To explore the detection mechanism, three unique polar binding sites on albumin are computationally identified, where the multivalent tetrazolate–lysine interactions contribute to the tight binding and restriction of the molecular motion of the AIE probes. The key role of lysine residues is verified by the detection of poly-l-lysine. Moreover, we applied the fluorogenic method to quantify urinary albumin in clinical samples and found it a feasible and practical strategy for albumin analysis in complex biological fluids.
•The Fe87M8B5 (M = Zr, Ce) alloys were successfully prepared into amorphous ribbons;•The Fe87Ce8B5 amorphous ribbon show higher − ΔSmpeak and lower Tc than the Fe87Zr8B5 amorphous ribbon;•The ...mechanism for the different − ΔSmpeak and Tc between the Fe87M8B5 (M = Zr, Ce) amorphous ribbon was investigated;
The magnetic and magnetocaloric properties of the amorphous Fe87Ce8B5 ribbon were investigated in comparison with the Fe87Zr8B5 amorphous alloy (AA). It was found that the Fe87Ce8B5 AA shows a rather high maximum magnetic entropy change (−ΔSmpeak, ∼ 3.65 J/(kg × K) under 5 T and 1.47 J/(kg × K) under 1.5 T) near its Curie temperature (Tc, ∼ 283 K), which is much higher than the − ΔSmpeak of the Fe87Zr8B5 AA near 306 K. The mechanism for the enhanced − ΔSmpeak and decreased Tc by the Ce substitution for Zr in the Fe87M8B5 AAs were investigated. The results are helpful for achieving higher − ΔSmpeak of the iron-based AAs at the temperatures slightly lower than the room temperature, which is conducive to construct a table-like magnetic entropy change (−ΔSm) curve with higher average − ΔSm within the working temperature range of a domestic air conditioner.
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