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The sensitive detection of antioxidants in food is essential for the rational control of their usage and reducing potential health risks. A simple three-dimensional (3D) electrode integrated with an anti-fouling/anti-interference layer possesses great potential for the direct and sensitive electrochemical detection of antioxidants in food samples. In this work, a 3D electrochemical sensor was developed by integrating a 3D graphene electrode (3DG) with vertically ordered mesoporous silica film (VMSF), enabling highly sensitive detection of the common antioxidant, butylated hydroxyanisole (BHA), in food samples. A simple electrochemical polarization was employed to pre-activate the 3DG electrode (p3DG), enhancing its hydrophilicity. Using the p3DG as the supporting electrode, stable modification of VMSF was achieved using the electrochemical assisted self-assembly (EASA) method, without the need for any adhesive agents (VMSF/p3DG). Taking BHA in food as a model analyte, the VMSF/p3DG sensor demonstrated high sensitivity, due to the enrichment by nanochannels, towards BHA. Electrochemical detection of BHA was achieved with a linear range of 0.1 μM to 5 μM and from 5 μM to 150 μM with a low limit of detection (12 nM). Owing to the fouling resistance and anti-interference capabilities of VMSF, the constructed 3D electrochemical sensor can be directly applied for the electrochemical detection of BHA in complex food samples. [ABSTRACT FROM AUTHOR]

In order to promote the industrialization of the large deformation technology of carbon fiber composites, this paper studies a new method of forming of helical carbon fiber reinforced aluminum matrix composite. The purpose is to solve the problem of large deformation of carbon fiber with low elongation and metal matrix with high elongation. By introducing carbon fiber with helical space structure into the aluminum matrix, the helical carbon fiber reinforced aluminum matrix composites were prepared and the subsequent drawing deformation was carried out. Here we systematically studied the large plastic deformation behavior of helical carbon fiber reinforced aluminum matrix composite via a combination of numerical simulations and experiments, and analyzed the deformation law and stress of helical carbon fiber in the deformation process. We found that the plastic deformation of the composite causes local stress concentration around the helical carbon fiber, and the helical carbon fiber will move synchronously with the aluminum matrix during the deformation, and receive the pressure from the aluminum matrix. Second, the best process parameters obtained from the simulation, that is, the drawing die angle α = 7°, when five-pass drawing experiments were carried out, the total deformation reached 58%, and the average elongation of a single pass was 18.9%. The experimental show carbon fiber reinforced aluminum matrix composite with helical space structure can achieve large deformation and high strength. The experimental and simulation are in general agreement, which verifies the correctness of the carbon fiber helical structure model. [ABSTRACT FROM AUTHOR]

Carbon fiber is mainly distributed in the shape of short fibers and continuous fiber bundles as the reinforcing phase in metal matrix composites, and it is seldom studied as braided rope shaped to reinforce the matrix. For this paper, the pretreatment and the surface metallization of the carbon fiber braided rope were studied. Besides, the casting experiments of aluminum-based carbon fiber braided rope composites were performed without external pressure. XPS analysis shows that the surface of the carbon fiber braided rope treated with ultrasonic degumming contains many hydrophilic oxygen-containing functional groups C-OH, C=O, COOH, etc., which can effectively improve the wettability between the carbon fiber braided rope and the aluminum matrix. SEM, EDS, and XRD were used to analyze the micromorphology and structure of the copper plating on the surface of carbon fiber braided ropes obtained from different pH plating solutions. When pH is 12, a continuous, uniform, and dense layer was formed on the surface of carbon fiber braided ropes. In addition, copper coating can effectively inhibit the formation of Al4C3 brittle phase. Finally, the mechanical properties results indicated that the tensile strength of the carbon fiber bundle and carbon fiber rope reinforced composite materials were 69 MPa and 83 MPa, respectively, indicating that the reinforcing effect of the carbon fiber rope is better than that of the carbon fiber bundle. [ABSTRACT FROM AUTHOR]

Thermal conductivity is required for developing high-power microwave technology. Diamond has the highest thermal conductivity in nature. In this study, a diamond film was synthesized by microwave plasma chemical deposition, and then long and short conductive graphite fibers were introduced to the diamond films by laser ablation. The permittivity of the samples in the K-band was measured using the transmission/reflection method. The permittivity of diamond films with short graphite fibers increased. The increase in real part of permittivity can be attributed to electron polarization, and the increase in the imaginary part can be ascribed to both polarization and electrical conductivity. The diamond films with long graphite fibers exhibited a highly pronounced anisotropy for microwave. The calculation of microwave absorption shows that reflection loss values exceeding −10 dB can be obtained in the frequency range of 21.3–23.5 GHz when the graphite fiber length is 0.7 mm and the sample thickness is 2.5 mm. Therefore, diamond films can be developed into a microwave attenuation material with extremely high thermal conductivity. [ABSTRACT FROM AUTHOR]