Microfluidic Microwave Sensor Loaded with Star-Slotted Patch for Edible Oil Quality Inspection.

In this paper, we present a new microfluidic microwave sensor loaded with a star-slotted patch for detecting the quality of edible oil. The relative dielectric permittivity and the quality of edible oil will change after being heated at a high temperature. Therefore, the quality of edible oil can be detected by measuring the relative dielectric permittivity of edible oil. The sensor is used to determine the edible oil with different dielectric permittivity by measuring the resonance frequency offset of the input reflection coefficient, which operates at 2.68 GHz. This sensor is designed based on a resonant approach to provide the best sensing accuracy and is implemented using a substrate integrated waveguide structure combined with a pentagonal slot antenna operating at 2.3~2.9 GHz. It can detect greasy liquids with the real part of the complex permittivity ranging from two to three.

Ni and nitrogen-codoped ultrathin carbon nanosheets with strong bonding sites for efficient CO2 electrochemical reduction.

Single-atom catalysts have attracted wide attention recently because of their unique size quantum effect and superior atom utilization in CO2 reduction reaction (CO2RR). Here, ultrathin Ni and nitrogen-codoped carbon nanosheets (Ni-N-CNSs) were proposed by a facile in-situ pyrolytic strategy. The ultrathin porous structure of Ni-N-CNSs affords large surface area, rich mesoporous volume and vast uniformly dispersed Ni atoms. The optimized catalyst exhibits a high CO Faradaic efficiency of nearly 100%, partial current density of 121.4 mA mg-1, CO production rate of 37.7 µmol mg-1 min-1, and super durability. In addition, the first principles calculations and the Mulliken charge analyses reveal the Ni sites show high bonding force towards the CO2 molecules, which gives rise to the high activity and selectivity of Ni-N-CNSs in CO2RR.

Nonlinear optical properties of sodium copper chlorophyllin in aqueous solution.

BACKGROUND: Sodium copper chlorophyllin (SCC), as one of the derivatives of chlorophyll - with its inherent green features; good stability for heat, light, acids and alkalies; unique antimicrobial capability; and particular deodori zation performance - is widely applied in some fields such as the food industry, medicine and health care, daily cosmetic industry etc. SCC, as one of the metal porphyrins, has attracted much attention because of its unique electronic band structure and photon conversion performance. To promote the application of SCC in materials science; energy research and photonics, such as fast optical communications; and its use in nonlinear optical materials, solar photovoltaic cells, all-optical switches, optical limiters and saturable absorbers, great efforts should be dedicated to studying its nonlinear optical (NLO) properties. METHODS: In this study, the absorption spectra and NLO properties of SCC in aqueous solution at different concentrations were measured. The Z-scan technique was used to determine NLO properties. RESULTS: The results indicated that the absorption spectra of SCC exhibit 2 characteristic absorption peaks located at the wavelengths 405 and 630 nm, and the values of the peaks increase with increasing SCC concentration. The results also showed that SCC exhibits reverse saturation absorption and negative nonlinear refraction (self-defocusing). CONCLUSIONS: It can be seen that SCC has good optical nonlinearity which will be convenient for applications in materials science, energy research and photonics.