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[Objective] The spatial and temporal evolution patterns and driving mechanisms of multifunctional cropland were analyzed in order to provide support for ensuring food security and promoting the coordinated development of regional multifunctional cropland along with socio-economic development. [Methods] The entropy power method, hierarchical analysis method, comprehensive index method, GIS spatial visualization analysis, and geographic probe were used in this study. [Results] ① The comprehensive function of arable land in each county of Poyang Lake p lain generally increased from 2000 to 2020, and was significantly influenced by socio-economic development level. Specifically, improvement of the comprehensive function of arable land was given priority to areas with faster socio-economic development, such as Nanchang County, Anyi County, and other areas around Nanchang City. ② Different trends of multi-functional changes were observed for arable land in Poyang Lake plain during the 20 years of the study. Production and landscape aesthetic functions showed a growing trend, while ecological maintenance and social security functions show a decreasing trend. These patterns indicated that even though the production function of arable land in Poyang Lake plain improved, it was difficult to guarantee the growing food and economic demand, while the rapid development of secondary and tertiary industries gradually decreased the proportion of economic contribution that arable land can provide. ③ The multi-functional development level of arable land in Poyang Lake plain was influenced by both social and natural factors. The social factors could be regulated by policies such as improving the basic conditions of agricultural production, guaranteeing the minimum income of rural residents, and improving the medical welfare standard of rural residents, while the natural environment requires human intervention to protect and restore the ecological environment. [Conclusion] A variety of factors jointly influenced the level of multifunctional development of arable land in Poyang Lake plain, and the rational formulation of policies related to the protection and utilization of arable land and the protection of rural residents’ living standards that have a facilitating effect on improving the level of multifunctional development of arable land.

A stepped reflective cup is designed to improve the industry situation that it is difficult to have both lighting angle and lighting uniformity of miner’s lamp. The luminous characteristics of LED light source and the lighting requirements of underground working conditions of coal mine are considered in the design. The simulation is carried out with TracePro. The simulation results show that after the secondary light distribution through the reflective cup, the light source energy is redistributed, and the far central range, wide illumination range and the uniformity of main illumination areas can be obtained at the same time. The idea of applying image recognition technology to analyze lighting uniformity is proposed for the first time, and the designed reflective cup is verified by compiling relevant programs in MATLAB. The results show that the lighting uniformity of miner’s lamp using stepped reflective cup can reach 82.17%, which is about 10 percentage points higher than that of common deep light cup and shallow light cup.

ObjectiveIn order to reduce the risk of export, the current status of the maximum residue limits (MRLs) of pesticides in garlic at home and abroad were studied. And on this basis, the suggestions for improving the standards of pesticide residues of China in garlic were given.MethodsCurrent and valid standards of pesticide MRLs in garlic from European Union (EU), International Codex Alimentarius Commission (CAC), Japan, South Korea and China were collected, compared and analyzed.ResultsThere are 129 pesticide MRLs related to garlic in China, and the EU, Japan, South Korea and CAC standards have 510, 252, 173 and 23 pesticide MRLs, respectively. There are 93, 67, 56 and 18 pesticides in the EU, Japan, South Korea and CAC standards that are the same as those in China, respectively. Among them, 49, 19, 22 and 4 pesticides MRLs are lower than China, respectively.ConclusionDue to the different dietary structures and registered pesticides in different countries, China and the EU, CAC, Japan and South Korea have significant differences in the total number of pestcides and their MRLs. It is recommended to improve relevant standards in China based on the actual garlic production and dietary needs in China.

ObjectiveTo detect the content of Cadmium (Cd) in crab sold in Beijing from 2018 to 2020 and carry out health risk assessment.MethodsRandom sampling method was adopted, common crab sold in Beijing were sampled. The content of Cd was determined by atomic absorption spectroscopy to evaluate the health risk.ResultsA total of 83 crab samples were collected. The average level of Cd in crabs was 0.647 mg/kg. Among them, the Cd content in freshwater crabs ranged from 0.043-0.620 mg/kg with the average level of 0.183 mg/kg. Whereas, the concentration of Cd in seawater crabs ranged from 0.033-3.200 mg/kg with the average level of 1.070 mg/kg. Moreover, the difference of the over-limit ratio was significant during three year. The THQ value and total THQ value of heavy metals in crab ingested by children and adults decreased in turn. The THQ values of Cd were less than 1.ConclusionAlthough the results indicated that there were certain amounts of Cd residues in the crabs sold in Beijing during 2018-2020, the dietary risk was relatively low because of the low intake.

Cornus officinalis and Dioscorea opposita were used as raw materials, and oolong tea powder, peach powder and mango powder were used as auxiliary ingredients to make C. officinalis and D. opposita compound bagged tea, and polysaccharide content and sensory scores were used as the indexes of examination, the formulation was optimized by single factor test combined with orthogonal test, and the volatile flavor components were extracted in the tea broth by the solvent extraction ( methylene chloride extraction) method, and the volatile flavor components were analyzed by the electronic nose technique combined with the gas chromatography-mass spectrometry (GC-MS) method. The results showed that the optimal formulation of C. officinalis and D. opposita compound bagged tea was 12 g of C. officinalis powder, 30 g of D. opposita powder, 10 g of oolong tea powder, 14 g of mango powder, 14 g of peach powder, and the polysaccharide content of the product was (1. 25±0. 74) mg/3 g, the organoleptic score was (83. 83±4. 56), and the overall score was 91. 91. The tea bags maintained their integrity and did not disintegrate after brewing, the tea broth was delicate, sweet and sour, clarified and transparent without precipitation, and the smell was fresh and fragrant. There were sulfide, aromatic components, nitrogen oxides and other flavor substances in the tea broth, and a total of 53 volatile flavor components were further identified, including 40 alkanes, 4 esters, 2 alcohols, 2 aldehydes, 2 ketones, and 3 other types, of which alkanes, esters, alcohols, aldehydes, and ketones were the typical aroma components. [ABSTRACT FROM AUTHOR]

Considering the characteristics of products and users, a set of leakage rate testing device is designed for mine respirator masks. In the device, 10 sets of imitation models of human heads are designed which can cover the different facial features of Chinese adult men. The accurate and stable detection of the leakage rate of masks can be realized without the participation of real people. The experimental results show that the standard deviation of oil mist concentration control is 3.02 mg/cm3, and the repeatability errors of leakage rate test for full masks and half masks are 0.6% and 1.2% respectively.

This paper proposes a particle swarm optimization based on credibility of solution and double archive to minimize makespan of flexible job-shop scheduling problem (FJSP). Firstly, the elite archive and the optimization archive are constructed to store the individual historical optimal position (Pbest) of the elite particle with better fitness value and the position of the particles that have made rapid progress, respectively. Secondly, it uses the particles in the elite archives to calculate the credibility of solution, and judge the evolutionary state of the current population according to the credibility of solution. The particles adjust the strength of learning from the two archives according to the evolutionary state to achieve a balance between convergence and diversity. Further, extensive experiments are carried out on 5 test problems of Kacem and 10 test problems of MK series, and the comparison with other algorithms according to the minimum completion time and average completion time proves the effectiveness of DAPSO in solving the FJSP problem. [ABSTRACT FROM AUTHOR]

Measurement of additive residues in food contact materials is important for safety monitoring at the initial stage. Most of the current studies focus on the determination of the migration amounts of chemical hazards from food contact materials into food simulants. Studies on chemical hazard residues in food contact materials are limited to monomers, oligomers, heavy metals, phthalic acid esters, and biphenols, which are known environmental pollutants. Only a few studies have investigated analysis methods for additive residues in food contact materials. In this study, the main factors (monitoring wavelength, chromatographic column, mobile phase, extraction solvent, etc.) that affect the accuracy and sensitivity of eight compounds, including three antioxidants, three light stabilizers, and two plasticizers, were investigated during sample preparation and instrument analysis. A method based on ultrahigh-performance liquid chromatography (UPLC) was developed for the simultaneous determination of these eight additives in polyethylene (PE). The PE food contact material sample was ground to homogenize the particle sizes under freeze-grinding. After comparing the extraction efficiencies of methylbenzene, chloroform, acetone, and acetonitrile, 2.0 g of the sample was extracted with methylbenzene at 80 ℃ and 10.34-11.72 MPa (1500-1700 psi) by accelerated solvent extraction (ASE) for 10 min once. The exaction solvent (10 mL) was transferred and concentrated to near dryness under a gentle stream of nitrogen gas and then re-dissolved in 10 mL of the initial mobile phase (70% (v/v) methanol in water). Finally, the eight compounds were analyzed by UPLC. After optimization of the analytical column and mobile phases, the eight analytes were separated on an ACQUITY UPLC BEH C 8 chromatographic column (100 mm×2.1 mm, 1.7 μm) by gradient elution using water and acetonitrile as the mobile phases. The column oven temperature, flow rate of the mobile phase, and injection volume were 30 ℃, 0.3 mL/min, and 5 μL, respectively. The analytes were detected by a diode assay detector (DAD) in the scanning range of 210 nm to 400 nm. The monitoring wavelength was set at 230 nm, 250 nm, 280 nm, and 330 nm. External standard calibration curves were used for quantification. Under the optimized conditions, the calibration curves for the eight compounds showed good linearity in the range of 0.2 μg/mL to 10 μg/mL, and the correlation coefficients were >0.999. The recoveries in spiked blank polyethylene samples at the level of 0.05% were in the range of 83.8% to 103.4%, with relative standard deviations (RSDs) ranging from 0.14% to 7.86%. To validate the method, PE reference materials containing these eight compounds were manufactured at the content level of 0.2% to 0.9%. The recoveries using the prepared reference materials ranged from 63.5% to 118.5%, and the RSDs were in the range of 4.61% to 15.6%. The limits of detection (LODs, S/N =3) of all the eight compounds were 0.005% and the limits of quantification (LOQs, S/N =10) were 0.02%, in compliance with the current legislation. To assess the feasibility and potential of the proposed approach for routine analyses of these eight compounds, the developed method was applied to the analysis of these compounds in ten PE food packages and PE gloves. In six samples, tris(2,4-di- tert -butylphenyl)phosphite (Irganox 168) was detected at a level of 0.02%-0.07%, which was lower than the maximum level of this compound in PE food contact material products regulated in GB 9685-2016 at 0.2%. The method is compliant with the current legislation, and it can be used for the monitoring and supervision of these eight additives in PE food contact materials.

An analytical method was established for the determination of 15 lipid regulators in fish meat by QuEChERS combined with ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap mass spectrometry (UPLC-Q/Orbitrap-MS). The samples were purified by optimized QuEChERS methods. The amounts of the adsorbent materials (primary secondary amine (PSA) (20, 60, 100, 140 and 180 mg), C18 (40, 100, 160, 220 and 280 mg) and sodium acetate (0.2, 0.6, 1.0, 1.4 and 1.8 g)) were optimized by the response surface method to obtain the best purification effect. The target compounds were separated on an XBridge-C18 column (100 mm×2.1 mm, 3.5 μm) using acetonitrile-0.1% (v/v) formic acid aqueous solution (containing 1.5 mmol/L ammonium acetate) as the mobile phases by a gradient elution program. Qualitative and quantitative analysis of the target compounds were performed in the full scan and secondary mass spectrometry scan (dd-MS 2 ) modes with positive and negative ionization. The target compounds showed good linear relationships in their respective ranges, with correlation coefficients ( R 2 ) greater than 0.99. The limits of detection (LOD, S/N =3) and limits of quantification (LOQ, S/N =10) were in the range of 0.2-1.0 μg/kg and 0.3-3.1 μg/kg, respectively. The average recoveries were 76.4%-116.0% at LOQ, 2-fold LOQ, and 10-fold LOQ levels. The intra-day relative standard deviations (RSDs) were 1.0%-7.9%, and the inter-day RSDs were 1.7%-18.4%. The method is simple, sensitive and accurate, and it is suitable for the determination and quantification of lipid regulators in fish meat.

Bisphenols, which are environmental endocrine disruptors, are widely found in food packaging materials and the environment, polluting the ecological environment and inducing harm to human health. Bisphenol residues constitute an important food safety problem at present. Hence, detecting the bisphenol content in food and environmental samples is of great significance for protecting human health. Because of the low concentration and matrix interference, a combination of sample pretreatment and instrumental analysis is imperative for improving the detection efficiency and enhancing the analytical sensitivity and reliability. Common pretreatment and analysis methods mainly include liquid-liquid extraction, microwave-assisted extraction, solid-phase extraction, solid-phase microextraction, matrix-dispersive solid-phase extraction, and QuEChERS. Common instrumental analysis methods include liquid chromatography, gas chromatography, capillary electrophoresis, immunoassays, and biosensors. In this paper, various methods for sample pretreatment and instrumental analysis of bisphenols in food and environmental samples are reviewed, with the aim of providing a reference for the residue monitoring of bisphenols.