Electrochemical sensors for detecting micromolecule organics are desirable for improving the perception of environmental quality and human health. However, currently, the electrochemical sensors... Show moreElectrochemical sensors for detecting micromolecule organics are desirable for improving the perception of environmental quality and human health. However, currently, the electrochemical sensors for formaldehyde are substantially limited on the market due to the long-term unsolved problems of the low electrooxidation efficiency and CO poisoning issue of commercial Pd catalysts. Here, a 2D Cr-doped Pd metallene (Cr-Pdene) with few atomic layers is shown as an advanced catalyst for ultrasensitive and selective sensing of formaldehyde via a highly efficient formaldehyde electrooxidation. It is found that the doping of Cr into Pd metallene can efficiently optimize the electronic structure of Pd and weaken the interaction between Pd and CO, providing an anti-poisoning means to favor CO2 production and suppress CO adsorption. The Cr-Pdene-based electrochemical sensor exhibits one order of magnitude higher detection range and, especially, much higher anti-interference for formaldehyde than that of the conventional sensors. Most importantly, it is demonstrated that the Cr-Pdene can be integrated into commercializable wireless sensor networks or handheld instruments for promising applications relating to the environment, health, and food. Show less
Zhang, C.; Hu, M.; Dong, L.; Xiang, P.; Zhang, Q.; Wu, J.; ... ; Shi, S. 2018
Rapid urbanization drives massive construction, which, in return, leads to ever increasing urban metabolism challenges on the provision of raw materials, as well as the disposal of construction and... Show moreRapid urbanization drives massive construction, which, in return, leads to ever increasing urban metabolism challenges on the provision of raw materials, as well as the disposal of construction and demolition waste. Due to its large volume, the transporting and processing of these materials cause considerable greenhouse gas emissions and land use change. With this circumstance, shortening the supply chains of urban construction by efficient recycling of construction and demolition waste becomes a frontier field for the circular transition of cities. It is particularly important in current China, where the concrete recycling is still rare. This paper aims to map the opportunities and potentials of concrete recycling on the mitigation of greenhouse gas emissions and land use change, with an integrated material flow analysis and life cycle assessment for the case study city – Chongqing, China. For the baseline year 2015, four scenarios representing various recycling routes in Chongqing have been explored: (1) improving brick manufacturing; (2) recycling on-site for road base filling; (3) recycling aggregate for prefabricated concrete component and (4) recycling concrete aggregate for structure use. Results highlighted that different technological routes have different potentials to increase recycling rates but all generate co-benefits on greenhouse gases mitigation and land transformation reduction. Recycling of stony construction and demolition waste for high value concrete aggregate has the biggest potential to bring the co-benefits on greenhouse gases mitigation and land use reduction. Besides, on-site recycling for road-base aggregates also presents a high performance, especially on greenhouse gases mitigation in transport. Based on the sensitivity analysis, policy implications were discussed, highlighting the necessity of to develop the recycling routes that substitute primary gravel with aggregates recycled from the stony waste; unlocking the existing recycling capacity and restricting landfilling. Show less
Zhang, Z.; Ke, M.; Qu, Q.; Peijnenburg, W.J.G.M.; Lu, T.; Zhang, Q.; ... ; Qian, H. 2018
The total synthesis of mixed-sequence alginate oligosaccharides, featuring both β-D-mannuronic acid (M) and α-L-guluronic acid (G), is reported for the first time. A set of GM, GMG, GMGM, GMGMG,... Show moreThe total synthesis of mixed-sequence alginate oligosaccharides, featuring both β-D-mannuronic acid (M) and α-L-guluronic acid (G), is reported for the first time. A set of GM, GMG, GMGM, GMGMG, GMGMGM, GMGMGMG, and GMGGMG alginates was assembled using GM building blocks, having a guluronic acid acceptor part and a mannuronic acid donor side to allow the fully stereoselective construction of the cis-glycosidic linkages. It was found that the nature of the reducing-end anomeric center, which is ten atoms away from the reacting alcohol group in the key disaccharide acceptor, had a tremendous effect on the efficiency with which the building blocks were united. This chiral center determines the overall shape of the acceptor and it is revealed that the conformational flexibility of the acceptor is an all-important factor in determining the outcome of a glycosylation reaction. Show less
