Abstract To improve the crashworthiness and energy absorption of thin-walled tube structures, a bionic thin-walled tube was designed based on the structural characteristics of antler osteon and the principle of structural bionics and had the same inner and outer diameters and the same gradient thickness as antler osteon. A nonlinear finite element method is used to simulate the crashworthiness of a thin-walled tube with equal gradient thickness variation (EGTTS) under axial and oblique loads. The crashworthiness of EGTTS-7 (Egtts with 7 layers) was evaluated using the complex proportional assessment(COPRAS). A multi-objective particle swarm optimization (MOPSO) algorithm was used to optimize the EGTTS-7 and the Pareto boundary was used to obtain the optimal structure parameters of the EGTTS-7 by using the loading angles of 0°, 10°, 20°, and 30°. It is found that the crashworthiness of the EGTTS is best when the axial load weight factor of the case is large. Compared with EGTTS and circular tubes(CT), F max can be reduced by up to 50.1% and EA can be increased by up to 22.7%.
The study established a method of rapid cleanup using an easy to operate syringe filter and gas chromatography coupled to an electron capture detector (GC-ECD) to detect 37 pesticides in Pericarpium Citri Reticulatae and related products. The critical parameters related to clean-up efficiency were optimized. The adsorbents, which included PestiCarb (0.5 g), primary secondary amine (PSA, 0.25 g) and Florisil (1.0 g), were loaded in turn and push-pull was performed 4 times within a 1 min operating time. Under optimized conditions, the recovery of pesticides ranged from 61.6 to 128.6% at three spiked levels (25, 50, 500 µg kg-1). After analysis by GC-ECD and confirmation by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS), 8 out of 57 batches of peels were found to be contaminated with hexachlorobenzene, dicofol, procymidone and p,p’-DDE (dichlorodiphenyldichloroethylene). The most frequently (10.5%) occurring pollutants were hexachlorobenzene and dicofol. In addition, 5 batches contained prohibited or restricted persistent organochlorines at levels above regulations, and 5 of these peels contained more than two pesticides.