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[Display omitted] • SERS hybrid substrate with the sandwich structure was fabricated by a simple way. • Enhancement factors of up to 3.10 * 104 were achieved by adjusting the particle size. • Direct detection of trace amounts of pesticides on the surface of fruits is 10-9 g/ml. The overuse of mixed pesticides poses a threat to both the ecosystem and human health, yet general pesticide detection methods are complex in terms of steps, such as the need for pretreatment and cleaning. Surface-enhanced Raman scattering (SERS) has been used for real-life trace detection of residues due to its rapid detection and ultra-high sensitivity. Here, we prepared a novel Ti 3 C 2 Tx (MXene)-noble metal hybrid flexible substrate with a layer of MXene on top of flower-like Ag nanoparticles (AgNFs), and finally grew Au nanoparticles (AuNPs) by galvanic replacement and self-reduction reactions. The limit of detection (LOD) can be as low as 2 × 10-12 M by detecting 4-mercaptobenzoic acid (4MBA). For efficient sampling, transparent and flexible platform made of polydimethylsiloxane (PDMS) were used for the extraction and detection of thiabendazole (TBZ), thiram, methyl parathion (MP) and their mixtures. Notably, the lowest concentrations detected by swabbing on the tomato surface (3.7 ng/mL, 2.8 ng/mL) were lower than the EU maximum permissible limits of pesticides on raw fruits and vegetables (4.0 mg/L, 6.33 mg/mL). This high performance Ti 3 C 2 Tx-noble metal hybrid flexible substrate offers a great advantage in the trace detection of molecules. [ABSTRACT FROM AUTHOR]

Abstract: Four sulfated heteropolysaccharide fractions (OJP-1, OJP-2, OJP-3 and OJP-4) were isolated and purified from the tuber of Ophiopogon japonicus by DEAE-Sepharose Fast Flow and Sepharose 6 Fast Flow column chromatography. OJP-1, the least sulfated product, was sulfated synthetically to OJP-1S. Their chemical–physical properties were determined by chemical methods, GC, FT-IR spectroscopy, and HPLC. The antioxidant and immunomodulation activities of these fractions were also investigated. The content of hexuronic acid and sulfate were decreased in the order OJP-4>OJP-3>OJP-2>OJP-1 and OJP-1S>OJP-4>OJP-3>OJP-2>OJP-1, respectively. In comparison with OJP-1, other polysaccharides showed stronger 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and hydroxyl radical scavenging activity. Five polysaccharides also exhibited remarkable macrophage-activating capability by the promotion of phagocytic capacity, energy metabolism rate, NO and interleukin-1 production. It was significantly different between five polysaccharides (P <0.01) and decreased in the order OJP-1S>OJP-4>OJP-3>OJP-2>OJP-1. Taken together, our results suggested that hexuronic acid and sulfate were effective indicators of antioxidant and immunomodulation activity of polysaccharide. [Copyright &y& Elsevier]

Highlights • The plant polyketide synthase is required for the sporopollenin precursor biosynthesis. • Knockout of the rice OsPKS1 leads to abnormal bacula deposition and ubisch body structures for sexine formation. • This protein was preferentially localized to the ER in tapetal cells during microspore development. • The function of polyketide synthase in sporopollenin synthesis pathway are conserved in rice and Arabidopsis. Abstract The sporopollenin precursors, as a general constituent of sexine, are synthesized in the tapetum and deposited on the pollen surface after transportation and processing. The polyketide synthase condenses the acyl-CoA into a hydroxyalkyl α-pyrone, which is predicted to be a component of the sporopollenin precursors. In this study, we found that the rice POLYKETIDE SYNTHASE 1 (OsPKS1) was the orthologue of Arabidopsis POLYKETIDE SYNTHASE A/LESS ADHESIVE POLLEN 6 (PKSA/LAP6) through sequence alignment. The OsPKS1 knockout mutants obtained by Crispr-Cas9-mediated editing exhibited a complete male sterile phenotype. Cytological observations revealed that abnormal bacula deposition and ubisch body structures for sexine formation led to pollen rupture in ospks1. The expression analysis showed that the OsPKS1 was highly expressed in tapetal cells and anther locules from stage 9 to stage 11 during anther development in rice. Subcellular localization demonstrated that the OsPKS1 protein was preferentially localized to the ER. The genomic sequence of OsPKS1 driven by the PKSA/LAP6 promoter restored the sexine pattern of Arabidopsis pksa/lap6. These results indicated that OsPKS1 is required for sexine layer formation in rice and functionally conserved in the sporopollenin synthesis pathway. [ABSTRACT FROM AUTHOR]

The southwest karst area is considered to have the most vulnerable groundwater environment in China. Groundwater quality is an important factor restricting sustainable economic development. In this study, traditional water chemistry method, water quality index (WQI), and hazard index (HI) were applied to comparatively analyze the hydrochemical characteristics of groundwater and the water quality in the exposed karst region (EKR) and buried karst region (BKR) in Bama, a typical karst area in southwest China. Generally, the main water type was Ca/Mg–HCO 3. Due to the predominance of dissolution of carbonate rocks in EKR and silicate rocks in BKR, higher total dissolved solids (TDS), Ca and HCO 3 − concentrations, and lower H 2 SiO 3 content were detected in groundwater in EKR compared with BKR. As affected by weathering of rocks such as lead-zinc ore, the maximum concentrations of Zn and Sr were 11.23 mg/L and 13.30 mg/L, showing that mineral water resources are widely distributed in Bama. The ion ratios and isotope abundances (δD and δ18O) in groundwater samples indicated stronger evaporation and rock-water interaction in EKR than BKR. Human activities exerted a more significant influence on the water quality in EKR compared to BKR. The mean WQI value also suggested that the groundwater quality was better in BKR (9.56) than EKR (12.17). Although 95.7% of the water samples in the study area were classified as excellent based on their WQI values, 4.3% of the water samples still had significant health risks (HI > 1) due to the high Sb, Zn, As, and Sr concentrations. It is recommended to reduce anthropogenic pollution in EKR and develop a plan for clean production of mineral water industry according to local conditions, which will help the sustainable development of the local economy. [Display omitted] • Groundwater hydrochemistry in exposed and buried karst regions is totally different. • Aquatic environment in exposed karst regions is more sensitive than buried ones. • Sb, As, and Zn are the main trace elements which may pose non-carcinogenic risks. • Groundwater quality assessment contributes to sustainable water management. [ABSTRACT FROM AUTHOR]

Abstract: In case hazardous contaminants are suddenly released indoors, the prompt and proper emergency responses are critical to protect occupants. This paper aims to provide a framework for determining the optimal combination of ventilation and evacuation strategies by considering the uncertainty of source locations. The certainty of source locations is classified as complete certainty, incomplete certainty, and complete uncertainty to cover all the possible situations. According to this classification, three types of decision analysis models are presented. A new concept, efficiency factor of contaminant source (EFCS), is incorporated in these models to evaluate the payoffs of the ventilation and evacuation strategies. A procedure of decision-making based on these models is proposed and demonstrated by numerical studies of one hundred scenarios with ten ventilation modes, two evacuation modes, and five source locations. The results show that the models can be useful to direct the decision analysis of both the ventilation and evacuation strategies. In addition, the certainty of the source locations has an important effect on the outcomes of the decision-making. [Copyright &y& Elsevier]