An Integrated Design of a Polypseudorotaxane‐Based Sea Cucumber Mimic

The development of integrated systems that mimic the multi-stage stiffness change of marine animals such as the sea cucumber requires the design of molecularly tailored structures. Herein, we used an integrated biomimicry design to fabricate a sea cucumber mimic using sidechain polypseudorotaxanes with tunable nano-to-macroscale properties. A series of polyethylene glycol (PEG)-based sidechain copolymers were synthesized to form sidechain polypseudorotaxanes with α-cyclodextrins (α-CDs). By tailoring the copolymers’ molecular weights and their PEG grafting densities, we rationally tuned the sizes of the formed polypseudorotaxanes crystalline domain and the physical crosslinking density of the hydrogels, which facilitated 3D printing and the mechanical adaptability to these hydrogels. After 3D printing and photo-crosslinking, the obtained hydrogels exhibited large tensile strain and broad elastic-to-plastic variations upon α-CD (de)threading. These discoveries enabled a successful fabrication of a sea cucumber mimic, demonstrating multi-stage stiffness changes

Active wideband higher-order raypath separation in multipath environment

International audienceMultiple raypaths propagation is caused by reflection and refraction at the surface and the bottom of the water column. In this study, an active wideband higher-order separation is proposed, which enables the separation of raypaths interrupted by colored noise (as traditionally found in ocean environments) in the angle-vs-time domain. A comparative study shows that the proposed algorithm achieves a more accurate separation than other algorithms. Moreover, with the proposed approach, it is not necessary to assume that the number of sensors is larger than that of the sources. Furthermore, numerical results validate the noise suppression property of the proposed method. (C) 2017 Acoustical Society of Americ

Effects of Mowing Heights on N 2 O Emission from Temperate Grasslands in Inner Mongolia

Abstract Grazing and mowing are two common practices for grassland management. Mowing is now recommended as an alternative to the traditional grazing for grassland conservation in Inner Mongolia, northern China. Many studies have revealed that mowing may alter ecosystem properties in various ways. However, little attention has been paid to the effect of mowing on trace gas emissions, especially on N2O flux. We conducted an experiment to investigate the effects of mowing on N2O fluxes from the semiarid grassland in Inner Mongolia. The mowing experiment, which started in 2003, comprised four mowing intensity treatments, i.e. mowing heights at 2 cm, 5 cm, 10 cm and 15 cm above the soil surface, respectively, and a control (non-mowing), with five replicates. Gas fluxes were measured through a closed static chamber technique during the growing seasons (usually from May to September, depending on local climate at the time) of 2008 and 2009, respectively. Our results showed that mowing decreased N2O emissions, above-ground biomass and total litter production. N2O emissions were greater in May and June than in other sampling periods, regardless of treatments (P < 0.05). A co-relationship analysis suggested that variations in seasonal N2O fluxes were mainly driven by variations in soil moisture, except in July and August. In July and August, above-ground plant biomass and soil total nitrogen became the major drivers of N2O fluxes under the soil temperatures between 16˚C and 18˚C. Though there were some uncertainties due to the low frequency of N2O flux measurement, our study mainly indicated that 5 cm mowing height might decrease N2O emissions in grasslands during the growing season, and soil * The first common authors. # Corresponding author. L. H. Zhang et al. 398 properties affected the magnitude of the reduction

The control of the formation of karst collapse through the ancient Yellow River Fault zone in Xuzhou, China

Xuzhou urban region has been seriously threatened by the geological hazards, such as karst collapse. Several collapses that had widely occurred were distributed in the ancient Yellow River Fault zone. Obviously, they were zonal and being controlled by the river fault zone. The karst was developing well in the fault zone and it connected the Cambrian and the Ordovician aquifer which made karst groundwater was very rich. The long-term pumping groundwater made the level up and down around the bedrock surface and the sandy soil covered directly on the karst aquifer which deposited with the form of paleochannels had changed. That is the main reason for the occurrence of karst collapse