Search

In the field of microplastics research, more accurate standardised methods and analytical techniques still need to be explored. In this study, a new method for the microplastics quantitatively and qualitatively analysis by two-phase (ethyl acetate-water) system combined with confocal Raman spectroscopy was developed. Microplastics can be separated from false-positive microplastics in beach sand and marine sediment, attributing to the hydrophobic-lipophilic interaction (HLI) of the two-phase system. Results show that the recovery rates of complex environment microplastics (polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyamide 66 (PA 66), polycarbonate (PC) and polyethylene (PE)) are higher than 92.98%. Moreover, the new technique can also be used to detect hydrophobic and lipophilic antibiotics, such as sulfamethoxazole (SMX), erythromycin (EM), madimycin (MD), and josamycin (JOS), which adsorbed on microplastics and are extracted based on the dissolving-precipitating mechanism. This innovative research strategy provides a new scope for further detection of marine environment microplastics and toxic compounds adsorbed on its surface.

The pollution of antibiotic resistance genes (ARGs) carried by microplastics (MPs) is a growing concern. Mangroves are located at the intersection of land and sea and are seriously affected by MP pollution. However, few studies have systematic research evaluating the transmission risk of ARGs carried by MPs in mangroves. We conducted in situ experiments by burying five different MPs (polypropylene, high-density polyethylene, polystyrene, polyethylene glycol terephthalate, and polycaprolactone particles) in mangroves with different surrounding environments. A total of 10 genes in the MPs of mangroves were detected using quantitative real-time polymerase chain reactions, including eight ARGs and two mobile genetic elements (MGEs). The abundance of ARGs in Guanhai park mangroves in living areas (GH) was higher than that of Gaoqiao mangroves in protected areas (GQ) and Beiyue dike mangroves in aquaculture pond areas (BY). Pathogenic bacteria, such as Acinetobacter, Bacillus, and Vibrio were found on the MP surfaces of the mangroves. The number of ARGs carried by multiple drug-resistant bacteria in the GH mangroves was greater than that in the GQ and BY mangroves. Moreover, the ARGs carried by MPs in GH mangroves had the highest potential transmission risk by horizontal gene transfer. Sociometric and environmental factors were the main drivers shaping the distribution characteristics of ARGs and MGEs. Polypropylene and high-density polyethylene particles are preferred substrates for obtaining diffuse ARGs. This study investigated the drivers of ARGs in the MPs of mangroves and provided essential guidance on the use and handling of plastics.

A mechanism for the dynamic shaft resistance of vertically vibrating single end-bearing and infinitely long piles is proposed through the use of elastodynamics. The generalized expression for the shaft resistance is obtained by means of Hamilton's principle. The shaft resistance is divided analytically into three parts, namely, the Winkler spring, the membrane and the participating mass of the surrounding soil. In light of the contributions of these three components of shaft resistance, a physical model is presented for the nature of single piles subjected to dynamic loading. The three components are obtained as explicit forms. The first is linear to the pile settlement. The second is related to the derivative of the second order of the pile settlement. The third involves the participating mass of the surrounding soil. The effect of the properties of the soil-pile system on the dynamic responses of the characteristic coefficients of the shaft resistance is investigated. The results indicate that the Winkler spring contributes the most to the shaft resistance. The contributions of the membrane and the participating mass of the surrounding soil are negligible for cases of high incident frequency.

Microplastics pollution poses a new threat to the environment of intertidal zone. The sea forest, mangrove, has been polluted by a large number of plastic debris worldwide. To fill the gaps in knowledge of mangrove rhizosphere microbes connected with the ‘plasticsphere’, a semi-controlled in situ exposure experiment for nine different types of microplastics were conducted in mangrove ecosystem. A sign of biodegrading was observed on polyethylene, polyamide 6 and polyvinyl chloride microplastics surface after 3 months exposure. We discovered that the metabolic activities of the dominant bacteria on certain microplastics were related to the specific groups on polymers molecule. The selective colonization may be driven by the chemotaxis of bacteria. Specially, microplastics biofilms of polyethylene, polyamide 6, polyvinyl chloride and expanded polystyrene possess distinctive dominant bacteria assemblages which have great significance in ecosystem processes involving carbon cycle or sulfur cycle. Community of mangrove soil microorganism and microplastic biofilm varies as the seasons changes. As a new niche, microplastics has higher inclusivity to bacteria than surrounding soil. Additionally, pathogens for human beings (Vibrio parahaemolyticus and Escherichia-Shigella) were detected both in microplastics and soil. We stress that the interaction between microplastics and rhizosphere microorganisms may affect the growth and health of mangrove plants. Besides, we point out that mangrove rhizosphere microorganism can be an ideal candidate for plastics-degradation.

Bone morphogenetic protein II (BMP2), a member of the transforming growth factor-beta (TGF-beta) superfamily, is highly expressed in osteoblasts and is a crucial regulator of osteogenic differentiation. Many observations clearly indicate the high potency of BMP2 as an inducer of osteogenesis, and it may be a novel therapeutic target for diseases associated with bone loss, especially in menopausal and postmenopausal women. To discover new agents that enhance the expression of the mouse BMP2, the authors developed a high-throughput assay to screen a synthetic and natural compound library. The cell-based high-throughput screen was conducted in 96-well plates using the clonal murine calvarial MC3T3-E1 cells. These cells were stably transfected with mouse BMP2 promoter-luciferase and calibrated with the known antiosteoporosis compound genistein. Among 3192 compounds screened, 3 agents (daidzein, formononetin, and 2-Acetyldibenzothiophene) were picked up by the high-throughput screening assay, and those compounds were identified as upregulators of BMP2 expression by real-time quantitative reverse transcription-polymerase chain reaction and flow cytometry. Thus, it is demonstrated that this screening model is useful for identifying lead compounds to treat osteoporosis and maintain bone metabolism balance.

A novel series of 1-(benzo[ b ]thiophen-2-yl)ethanone analogues were prepared and evaluated for enhancing BMP-2 expression. Compounds 1 – 5 , 7 , 8 , 12 , 13 and 16 , with upregulation rate values of 35.6%, 27.9%, 39.8%, 32.0%, 37.1%, 30.2%, 28.0%, 33.5%, 22.8% and 27.3% in vitro, respectively, at a concentration of 4 μM, exhibited potent effect for enhancing BMP-2 expression. We also found that compounds 1 and 12 produced a dose-dependent increase on bone histology and histomorphometry, and effectively reduced bone defects induced by ovariectomy in an ovariectomized rat model (OVX).