[en] An extrapolation chamber for measuring beta absorbed dose in tissue and its main properties are introduced. The device is developed with reference to ISO related recommendation in 1983. The diameter of the extrapolation chamber collected electrode is 30 mm. The distance between electrodes is variable from 0.15 to 10mm. The unparallel degree between electrodes is less than 0.005mm. The memory effect of the chamber lasts about 48 hours as it is irradiated to a β source with dose rate of 25 Gy/h for half an hour. The surface dose rates of natural uranium and some beta sources have been measured with the device and the measuring range of dose rate is 1.27 x 10^-3 - 2.37 x 10 Gy/h. The system unaccuracy and random error of the measured values are less than 4% and 1%, respectively

[en] Highlights: • The S-enantiomer degraded more slowly than the R-enantiomer in single soil system. • The S-enantiomer exerted long-term strong inhibition on soil microbial functions. • Earthworms accelerated the degradation of enantiomers, especially the S-enantiomer. • Earthworms alleviated inhibition of S-enantiomer on soil microbial functions. • Earthworms evidently stimulated potential degraders in the S-enantiomer treatment. This study investigated the effects of earthworms on the enantioselective degradation of chloroacetamide herbicide acetochlor with soil microorganisms in repeatedly treated soils. The S-enantiomer degraded more slowly and exerted stronger inhibition on soil microbial functions than the R-enantiomer in single soil system. A synergistic effect was observed between soil microorganisms and earthworms that accelerated the degradation of both the enantiomers, particularly the highly toxic S-enantiomer, which resulted in the preferential degradation of S-enantiomer in soil-earthworm system. Earthworms stimulated five potential indigenous degraders (i.e. Lysobacter, Kaistobacter, Flavobacterium, Arenimonas, and Aquicell), induced two new potential degraders (i.e. Aeromonas and Algoriphagus), and also significantly strengthened the correlations among these seven dominant potential degraders and other microorganisms. Notably, the relative abundances of Flavobacterium and Aeromonas in soil treated with earthworms for S-enantiomer were higher than those for R-enantiomer. Furthermore, earthworms significantly stimulated overall soil microbial activity and improved three microbial metabolic pathways, and xenobiotics biodegradation and metabolism, signal transduction, cell motility, particularly for the S-enantiomer treatment with earthworms, which alleviated the strong inhibition of S-enantiomer on microbial community functions. This study confirmed that earthworms accelerated the degradation of the highly toxic acetochlor S-enantiomer in soil, providing a potential approach in chloroacetamide herbicide-polluted soil remediation.

[en] Highlights: • Low-speed etching can suppress secondary electron emission better. • The parallel line pattern results in the anisotropy of the etched surface. • Secondary electron yield, resistance, and roughness are higher along the direction perpendicular to the groove-lines. • The roughness and resistance of the laser etched samples have multiplied. The performance of modern accelerators has been seriously affected by the electron cloud effect (e-cloud) caused by the accumulation of secondary electrons. Such problem can be effectively eliminated by laser-etching the inner surface of the vacuum chambers of the modern accelerators. In this work, surfaces of oxygen-free copper (OFC) were laser etched following either parallel lines or square-grid pattern with different scanning speeds. The secondary electron yields (SEYs), resistance, and roughness of the etched OFC samples were measured from various directions. The surfaces of etched OFC samples have been proven to form some regularly arranged grooves or cones, the geometries of which are directly related to the etching parameters. As a result, the parallelly etched samples exhibit apparent anisotropy. The sample etched along parallel lines, present higher SEYs, resistance and roughness when measured in the direction perpendicular to the groove-lines. But the sample etched following square-grid have little difference in the two directions and have a lower SEY value than the parallelly etched samples. Moreover, low-speed etching is more favorable to producing large aspect ratio and porosity structures, which is conducive to obtain lower SEY values.

[en] Highlights: • S-(+)-isomer enriched faster in earthworm than that of R-(-)-isomer • CYP450 and GST were superior to CarE in the detoxification of mandipropamid isomers • The DEGs in earthworms induced by S-(+)- isomer were greater than that by R-(-)-isomer • Bile secretion and thyroid hormone signaling pathways were significantly enriched • S-(+)-isomer may have a higher risk to earthworms than R-(-)-isomer As a novel chiral amide fungicide, the enantioselective behaviors of mandipropamid in the soil environment are unclear. Furthermore, there is a need to understand the stress response mechanisms of soil organisms exposed to mandipropamid isomers. Therefore, the selective bioaccumulation of mandipropamid isomers and detoxification mechanisms of earthworms (Eisenia fetida) were investigated in this study. Our results suggested that the enantioselective bioaccumulation of mandipropamid in earthworms occurred with the preferential enrichment of S-(+)-isomer. The activities of detoxification enzymes, such as cytochrome P450 (CYP450), glutathione-S-transferases (GST), and carboxylesterase (CarE), changed significantly upon exposure to S-(+)- and R-(-)-mandipropamid (particularly for CYP450 and GST). A transcriptome analysis revealed that more differentially expressed genes (DEGs) were observed under S-(+)-isomer exposure (15,798) than those under R-(-)-isomer exposure (12,222), as compared to the control group. These DEGs were mainly enriched in bile secretion and thyroid hormone signaling pathways, which were related to the detoxification process in earthworms. Moreover, the 20 DEGs, which exhibited the most profound changes (such as CYP2 and CYP3A4) in these pathways, were screened, clustered, and observed to be mainly involved in regulating the detoxification function of earthworm cells. These results indicated that detoxification systems played an essential role in the stress response to mandipropamid exposure. Additionally, earthworms were more sensitive to the stress induced by S-(+)-mandipropamid than that induced by R-(-)-mandipropamid. This is the first study to elucidate the mandipropamid detoxification mechanism of earthworms at the enantiomer level, which can be beneficial for remediating chiral pollutants.