[Sources, Disposal Technologies, and Environmental Impact of Photopolymerization-based 3D Printing Plastic Waste].

In the 3D printing industry, photopolymerization-based 3D printing is considered to have the characteristics of high printing accuracy and mature technology. Therefore, it is of wide concern in industrial application and academic research. With the rapid development of photopolymerization-based technology, photopolymerization-based plastic waste will inevitably be produced in the process of product manufacturing and use. This kind of plastic waste is a new type of organic solid waste with an incalculable growth rate, and its impact on the environment is difficult to predict. Based on available research results, the latest research progress of sources, disposal technologies, and environmental impact of photopolymerization-based plastic waste were summarized and analyzed. The results revealed that the photopolymerization-based plastic waste was covalently crosslinked with thermosetting plastic. It had relatively higher activation energy and photo-sensitive chromogenic groups. There were some potential hazards to the environment and biosome caused by the raw material, printing process, and waste disposal process of photopolymerization-based plastic. Therefore, prospects and suggestions were proposed for the possibility of future disposal of photopolymerization-based plastic waste, in order to provide a reference for developing the photopolymerization-based 3D printing industry.

The complete chloroplast genome of Elsholtzia fruticosa (D. Don) Rehd. (Labiatae), an ornamental plant with high medicinal value.

Elsholtzia fruticosa is an ornamental plant with high medicinal value. In this study, we sequenced and analyzed the complete chloroplast (cp) genome of the species. The complete cp sequence is 151,550 bp, including the large single-copy (LSC) region of 82,778 bp, the small single-copy (SSC) region of 17,492 bp, and a pair of invert repeats (IRs) regions of 25,640 bp. It encodes 132 unique genes in total, including 87 protein-coding genes, 37 transfer RNA genes (tRNAs), and eight ribosomal RNA genes (rRNAs). The comparative analysis of complete cp genomes showed that the genomic structure and gene order of E. fruticosa cps were conserved. The sequences of rps15, rps19, ycf1, ycf3, ycf15, psbL, psaI, trnG-UCC, trnS-GCU, trnR-UCU, trnL-UAG, trnP-UG, and trnL-UAA serve as hotspots for developing the DNA barcoding of Elsholtzia species. There are 49 SSR loci in the cp genome of E. fruticosa, among which the repeat numbers of mononucleotide, dinucleotide, trinucleotide, tetranucleotide, and pentanucleotides SSR are 37, 9, 3, 0, and 0, respectively. A total of 50 repeats were detected, including 15 forward repeats, seven reverse repeats, 26 palindromic repeats, and two complementary repeats. Phylogenetic analysis based on the complete cp genome and protein-coding DNA sequences of 26 plants indicates that E. fruticosa has a dose relationship with E. splendens and E. byeonsanensis.