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In excess, copper is toxic to plants. In the plants, Landoltia punctata and Lemna minor grown in mixed and monoculture, the effects of exposure to varying concentrations of copper (0.01, 0.1, 0.5 and 1mgL(-1) Cu) for seven days were assessed by measuring changes in the chlorophyll, protein and malondialdehyde (MDA) content, catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) activity. According to results, Cu levels in plants increased with increasing Cu concentration. The level of photosynthetic pigments and crude proteins decreased only upon exposure to high Cu concentrations. However, the starch and malondialdehyde (MDA) content increased. These results suggested a stress alleviation that was possibly the result of antioxidants such as CAT and SOD, the activities of which increased with increasing Cu levels. APX activity increased in L. punctata, but decreased in L. minor, under monoculture or mixed culture conditions. In addition, the duckweed in mixed culture exhibited increased antioxidant enzyme activities which provide increased resistance to copper in moderate copper concentrations. As the copper concentration increased, the duckweed in the mixed culture limited the uptake of copper to avoid toxicity., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The utilization of carbon resources stored in plastic polymers through chemical recycling and upcycling is a promising approach for mitigating plastic waste. However, most current methods for upcycling suffer from limited selectivity towards a specific valuable product, particularly when attempting full conversion of the plastic. We present a highly selective reaction route for transforming polylactic acid (PLA) into 1,2‐propanediol utilizing a Zn‐modified Cu catalyst. This reaction exhibits excellent reactivity (0.65 g gcat−1 h−1) and selectivity (99.5 %) towards 1,2‐propanediol, and most importantly, can be performed in a solvent‐free mode. Significantly, the overall solvent‐free reaction is an atom‐economical reaction with all the atoms in reactants (PLA and H2) fixed into the final product (1,2‐propanediol), eliminating the need for a separation process. This method provides an innovative and economically viable solution for upgrading polyesters to produce high‐purity products under mild conditions with optimal atom utilization. [ABSTRACT FROM AUTHOR]

• Cu-support ZrO 2 inverse catalysts exhibit higher STY MeOH from CO 2 hydrogenation. • The oxide-metal inverse interface is a more MeOH selective structure. • There exists an optimal coverage of nano-ZrO 2 on the Cu/ZrO 2 inverse catalyst. • The inverse interface favors conversion of key intermediates of formate to methoxy. • Methanol desorbs more easily on inverse catalysts than the conventional ones. The performance of Cu-based catalysts in the low temperature CO 2 conversion to methanol highly correlates with interfacial structure. In this paper, the interfacial structure of Cu/ZrO 2 catalysts is tuned by changing the molar ratio and precipitation sequence of Cu and Zr precursors in the oxalate precipitation method. Structural characterizations demonstrate that the interface structure gradually transforms from the conventional ZrO 2 -supported nano-Cu interface to the Cu-supported nano-ZrO 2 inverse interface with the ascending Cu/Zr ratio. The space–time yield (STY) of methanol over 90 mol Cu % Cu/ZrO 2 inverse catalyst is 518 g CH3OH /kg cat /h, which far exceeds that of the optimized 40 mol Cu % Cu/ZrO 2 catalyst (351 g CH3OH /kg cat /h). The inverse catalyst also exhibits the best methanol selectivity and lowest apparent activation energy. The correlation of the exposed Cu surface area, Cu particle size, and CO 2 adsorption capacity with STY methanol reveal that there is an optimal coverage of fine ZrO 2 particles and the Cu supported nano-ZrO 2 inverse configuration is a more suitable structure for methanol synthesis from CO 2. High-pressure in situ DRIFTS experiment shows that the adsorbed formate and methoxy intermediates over 90 mol Cu % Cu/ZrO 2 inverse catalyst are more reactive for further hydrogenation. In addition, the inverse configuration is more favorable for the methanol desorption from surface. The enhanced hydrogenation ability and relatively weak oxygenates adsorption of Cu-supported nano-ZrO 2 interface is probably the main reasons for the improved catalytic performances of inverse catalysts. [ABSTRACT FROM AUTHOR]