Properties of Graphene Oxide/Epoxy Resin Composites

The graphene oxide (GO) was obtained by pressurized oxidation method using natural graphite as raw materials. Then the GO/epoxy resin composites were prepared by casting. The mechanical and damping properties of composites were studied. As a result, the impact intensity of GO/epoxy resin composites was prominently improved with the content of the graphene oxide increasing. The glass transition temperature decreased and the damping capacity is improved

Near-Perfect Narrow-Band Tunable Graphene Absorber with a Dual-Layer Asymmetric Meta-Grating

A near-perfect narrow-band graphene-based absorber was fabricated using a resonant system integrated with an asymmetric meta-grating at a wavelength of 1550 nm. By optimizing the gap between the two grating strips, the absorption of monolayer graphene can be increased to 99.6% owing to the strong field confinement of the bottom zero-contrast grating (ZCG). The position of the absorption spectrum could be adjusted by tailoring the grating period or the thickness of the waveguide layer. Interestingly, absorption spectrum linewidth can be tailored by changing the thickness of the spacer layer. The accidental bound states in the continuum (BICs) are then demonstrated in the structure. Moreover, the designed structure realizes the dynamic adjustment of the absorption efficiency at a specific wavelength, which has excellent potential in integrated optical devices and systems

Corrosion behavior of AlCrFeTiNb and AlCrFeTiNb/(AlCrFeTiNb)N coatings in flowing lead–bismuth eutectic alloy with saturated oxygen concentration at 550 ℃

The AlCrFeTiNb monolayer coatings and the AlCrFeTiNb/(AlCrFeTiNb)N multilayer coatings are specially designed and prepared on ferritic/martensitic (F/M) steel cladding tube by magnetron sputtering technology, and their corrosion behavior in flowing (∼2 m/s) lead–bismuth eutectic (LBE) alloy with saturated oxygen concentration at 550 ℃ are systematically investigated. For the AlCrFeTiNb coatings, as the coating thickness increases, the LBE oxidation corrosion rate and the stress corrosion-induced crack density increase. The generation of penetrating cracks leads to the LBE infiltration and internal oxidation of the coatings. For the AlCrFeTiNb/(AlCrFeTiNb)N coatings, increasing the modulation period can reduce LBE oxidation corrosion rate, and the appropriate modulation period can also avoid the formation of penetrating cracks. The multilayer structure design has been proved to be effective in improving the LBE erosion resistance and inhibiting the stress corrosion-induced cracking by tailoring the appropriate modulation period and implanting more protective interlayers

Microwave Wire Interrogation Method Mapping Pressure under High Temperatures

It is widely accepted that wireless reading for in-situ mapping of pressure under high-temperature environments is the most feasible method, because it is not subject to frequent heterogeneous jointing failures and electrical conduction deteriorating, or even disappearing, under heat load. However, in this article, we successfully demonstrate an in-situ pressure sensor with wire interrogation for high-temperature applications. In this proof-of-concept study of the pressure sensor, we used a microwave resonator as a pressure-sensing component and a microwave transmission line as a pressure characteristic interrogation tunnel. In the sensor, the line and resonator are processed into a monolith, avoiding a heterogeneous jointing failure; further, microwave signal transmission does not depend on electrical conduction, and consequently, the sensor does not suffer from the heat load. We achieve pressure monitoring under 400 °C when employing the sensor simultaneously. Our sensor avoids restrictions that exist in wireless pressure interrogations, such as environmental noise and interference, signal leakage and security, low transfer efficiency, and so on

Chiral Arene Ligand as Stereocontroller for Asymmetric C-H Activation

Development of chiral ligands is the most fundamental task in metal-catalyzed asymmetric synthesis. In the last 60 years, various kinds of ligands have been sophisticatedly developed. However, it remains a long-standing challenge to develop practically useful chiral η6-arene ligands, thereby seriously hampering the asymmetric synthesis promoted by arene-metal catalysts. Herein, we report the design and synthesis of a class of facilely tunable, C2 symmetric chiral arene ligands derived from [2.2]paracyclophane. Its ruthenium(II) complexes have been successfully applied in the enantioselective C-H activation to afford a series of axially chiral biaryl compounds (up to 99% yield and 96% ee). This study not only lays chemists’ longstanding doubts about whether it is possible to use chiral arene ligand to stereocontrol asymmetric C-H activation, but also opens up a new avenue to achieve asymmetric C-H activation