A Comprehensive Evaluation of Dioxins and Furans Occurrence in River Sediments from a Secondary Steel Recycling Craft Village in Northern Vietnam.

This first study investigated the presence of dioxins and furans in river sediments around a craft village in Vietnam, focusing on Secondary Steel Recycling. Sediment samples were collected from various locations along the riverbed near the Da Hoi Secondary Steel Recycling village in Bac Ninh province. The analysis was conducted using a HRGC/HRMS-DFS device, detecting a total of 17 dioxin/furan isomers in all samples, with an average total concentration of 288.86 ng/kg d.w. The concentrations of dioxin/furan congeners showed minimal variation among sediment samples, ranging from 253.9 to 344.2 ng/kg d.w. The predominant compounds in the dioxin group were OCDD, while in the furan group, they were 1,2,3,4,6,7,8-HpCDF and OCDF. The chlorine content in the molecule appeared to be closely related to the concentration of dioxins and their percentage distribution. However, the levels of furan isomers did not vary significantly. The distribution of these compounds was not dependent on the flow direction, as they were mainly found in solid waste and are not water-soluble. Although the hepta and octa congeners had high concentrations, when converted to TEQ values, the tetra and penta groups (for dioxins) and the penta and hexa groups (for furans) contributed more to toxicity. Furthermore, the source of dioxins in sediments at Da Hoi does not only originate from steel recycling production activities but also from other combustion sites. The average total toxicity was 10.92 ng TEQ/kg d.w, ranging from 4.99 to 17.88 ng TEQ/kg d.w, which did not exceed the threshold specified in QCVN 43:2017/BTNMT, the National Technical Regulation on Sediment Quality. Nonetheless, these levels are still concerning. The presence of these toxic substances not only impacts aquatic organisms in the sampled water environment but also poses potential health risks to residents living nearby.

Antimicrobial secondary metabolites from the aerial parts of Perilla frutescens.

Phytochemical research of Perilla frutescens aerial parts led to isolation of 12 secondary metabolites, including one new 3-benzoxepin glucoside, perillafrutoside A (1), one new megastigmane glycoside, perillafrutoside B (2), and 10 known compounds. Their chemical structures were identified based on 1D/2D NMR, HRESIMS, and ECD spectroscopic analyses. The structure of 2 was elucidated based on revision of the previously reported stereoisomer, (6R,9R)-blumenyl α-L-rhamnopyranosyl-(1→6)-ß-D-glucopyranoside. Evaluation of their antimicrobial effect revealed that compounds 1 and 5-11 inhibit Enterococcus faecalis growth, compounds 6, 7 and 9 suppress Staphylococcus aureus growth, whereas compounds 6 and 11 attenuate Candida albicans growth. This is the first report of the isolation of 3-5, 8-10 and 12 from the genus Perilla and the antimicrobial effect of compounds 3, 8 and 10.

Pesticides in edible mushrooms in Vietnam.

Maximum residue limits (MRLs) for pesticides have been established for edible mushrooms in order to control quality and ensure benefits of consumers in numerous countries, especially areas comprising Europe. In this study, by means of optimising extract purification conditions, a high sensitivity and reliability method to simultaneously determine 180 pesticides in mushrooms has been proposed. Matrix effects were minimised by combining QuEChERS extraction and a mixed mode of SPE cleaned up with different adsorbent materials after sample preparation. The method was completely validated following the requirements of SANTE/12682/2019. The LOQs ranged from 2 to 5 µg/kg, well below the MRLs as regulated by the EU (10-50 µg/kg). Both relative standard deviation of repeatability (RSDr) and reproducibility (RSDR) were less than 20% and recoveries varied from 70 to 120%. Therefore, this method was considered to be suitable for routine analysis of multi-pesticide residues in edible mushrooms.

Gelless Secondary Growth of Zeolitic Aluminophosphate Membranes on Porous Supports with High Performance in CO2 /CH4 Separation.

Zeolitic aluminophosphate, a three-dimensional microporous material, with an average pore size of 0.38 nm is good candidate for molecular sieve application in CO2 gas separation. The separation of CO2 /CH4 gas mixtures for precombustion processes is desirable from the standpoint of both environmental concerns and energy efficiency. This study concerns an environmentally friendly method to synthesize zeolitic aluminophosphate thin films on various configurations and low-cost kaolin porous substrates with high performance in the separation of CO2 /CH4 mixtures. The membranes are prepared by a gelless seed growth method that uses lower amounts of chemicals, forms no liquid gel, chemical waste, or byproducts and generates no washing water. The obtained membranes show very high selectivity for CO2 with a CO2 /CH4 separation factor above 1000 in the separation of CO2 /CH4 gas mixtures.