Material flow analysis and statistical entropy evaluation of plastic packaging for express delivery in China

Encouraging the recycling of plastic packaging materials in express delivery is a necessary step toward environmentally friendly industrial development. In this study, we present a framework for analyzing the flow of materials in express plastic packaging, from production and manufacturing to consumption and recycling. In examining the use of recycled materials in post-consumer express plastic packaging and the destination of consumer packaging waste in 2020 and 2021, we found that 44.4% (1613.6 Gg) of the studied express plastic packaging was incinerated. Additionally, approximately 1296.6 Gg of express plastic packaging flowed into rural areas. Our calculations showed that the ΔRSE in 2020 was 15.1%, and on the condition that 25% separated collection with 80% recycling, ΔRSE would be - 0.5%. Results verified that separated collection is an important step in the recycling strategy for packaging materials. Survey data from universities in Beijing indicate that currently, 26% of college students are participating in the separate collection of packaging.

All-sealed paper-based electrochemiluminescence platform for on-site determination of lead ions

Lab-on-paper (LOP) devices are urgently required for the rapid development of point-of-care diagnoses and environmental assays. Herein, an all-sealed paper-based electrochemiluminescence (ECL) platform was developed to achieve lead ions (Pb²⁺) sensitive analysis via incorporating convenient plastic package technology. Benefiting from transparent plastic encapsulation, the sealed devices effectively avoided the interference of O₂. Meanwhile, myrica rubra-like Pt nanomaterials (MPNs) prepared by an economical and easy-to-operate ultrasound method were employed to catalyze H₂O₂ decomposition. With the help of Pb²⁺-specific DNAzymes, the oligonucleotide probe functionalized via MPNs could be detached from the device in the presence of target, resulting in the reduced ECL intensity. Moreover, the combination of modified paper electrode with functional regions separated by multiple layers of wax enhanced the practicability of the LOP device for rapid detection. Under the optimal conditions, the all-sealed platform achieved wide linear relationship ranging from 0.01 nM to 0.05 μM with a low detection limit of 0.004 nM for sensitive detecting Pb²⁺. It is believed that this platform could provide a robust, simple and versatile strategy for sensitive determination of heavy metal ions, and be applied in on-site contamination analysis in the future.

Effects of packaging parameters on the microbial decontamination of Korean steamed rice cakes using in-package atmospheric cold plasma treatment

The effects of packaging materials, package shape, and secondary packaging on the inactivation of indigenous mesophilic aerobic bacteria in Korean steamed rice cakes using in-package atmospheric dielectric barrier discharge cold plasma (ADCP) treatment were investigated. Inactivation of indigenous mesophilic aerobic bacteria by ADCP treatment (21 kV, 3 min) was significantly increased by 0.6 and 0.8 log CFU/g (p < 0.05) from 0.7 ± 0.1 and 0.5 ± 0.1 CFU/g, respectively, when polypropylene (PP) and low-density polyethylene (LDPE) were laminated with nylon, respectively. Secondary packaging lowered the inactivation level by 0.7-0.8 log CFU/g from 1.1 to 1.3 log CFU/g. In-package ADCP treatment did not alter the water vapor permeability, oxygen transmission rate, and tensile properties of PP, LDPE, nylon/PP, and nylon/LDPE. Thus, the results demonstrated that lamination of PP or LDPE with nylon and treatment before secondary packaging may be effective strategies for microbial inactivation by in-package ADCP treatment.