Aflatoxin B 1 (AFB 1 ) is a highly toxic mycotoxin that enters the human body through the food chain and poses a serious threat to human health. In this paper, polydopamine (PDA)-coated Fe 3 O 4 magnetic nanoparticles (Fe 3 O 4 @PDA MNPs) were prepared by the co-precipitation method to enrich aflatoxin from edible oil. Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometer were used to characterize the Fe 3 O 4 @PDA MNPs. Using the obtained Fe 3 O 4 @PDA MNPs as an adsorbent, a simple method for enriching AFB 1 from samples by magnetic solid phase extraction (MSPE) combined with fluorescence rapid detection was developed. The effects of the ratio of Fe 3 O 4 MNPs to PDA, adsorption dosage, sample volume, adsorption time, and elution time on enrichment of AFB 1 were investigated to determine the optimal experimental conditions. This method has good intraday and daytime precision.
Aramid III is a high-performance fiber obtained by bulk structure modification based on the molecular structure of Kevlar fiber. Unlike the intermittent heat treatment method of Armos, Aramid III is prepared by continuous heat treatment technology. In this paper, the effects of heat treatment temperature, tension, and speed on fiber properties are studied by orthogonal experimental design. It is concluded that temperature is the most critical factor affecting fiber tensile strength and elastic modulus. The effects of different heat treatment temperatures on the chemical structure, surface morphology, aggregation structure, and the fiber’s mechanical properties and thermal properties are studied. Results show that: the chemical structure of the fiber keeps unchanged and surface morphology of the fibers are similar under the different heat treatment temperatures; the crystallinity of the fiber increases with the increase of temperature; the orientation degree of the fiber increases slightly after heat treatment; with the temperature increasing, the elastic modulus of the fiber increases, the tensile strength and elongation at break increase to a peak and then gradually decrease; the thermal decomposition temperature of the fiber is 533°C, and the decomposition rate is slightly different at different heat treatment temperature.
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