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Correlated cell migration in fibrous extracellular matrix (ECM) is important in many biological processes. During migration, cells can remodel the ECM, leading to the formation of mesoscale structures such as fiber bundles. However, how such mesoscale structures regulate correlated single-cells migration remains to be elucidated. Here, using a quasi-3D in vitro model, we investigate how collagen fiber bundles are dynamically re-organized and guide cell migration. By combining laser ablation technique with 3D tracking and active-particle simulations, we definitively show that only the re-organized fiber bundles that carry significant tensile forces can guide strongly correlated cell migration, providing for the first time a direct experimental evidence supporting that matrix-transmitted long-range forces can regulate cell migration and self-organization. This force regulation mechanism can provide new insights for studies on cellular dynamics, fabrication or selection of biomedical materials in tissue repairing, and many other biomedical applications.

Lithium-sulfur batteries, owing to the multi-electron participation in the redox reaction, possess enormous energy density, which has aroused much attention. Nevertheless, the detrimental shuttle effect, volume expansion, and electrical insulation of sulfur, have hindered their application. To improve the cyclability, a functional host, consisting of Co nanoparticles and N-doped hollow graphitized carbon (Co-NHGC) material, is elaborated, which has the advantages of: 1) the graphitized carbon material working as an electronic matrix to improve the utilization rate of sulfur; 2) the hollow structure relieving the stress change caused by volume expansion; 3) the rich active sites catalyze the electrochemical reaction of sulfur and entrap polysulfides. These advantages significantly improve the performance of the lithium-sulfur batteries. Accordingly, the S@Co-NHGC cathode exhibits excellent initial specific capacity, high coulombic efficiency, and excellent rate performance. This work utilizes a novel method of dopamine in situ etching of a metal-organic framework to synthetize the Co-NHGC host of sulfur, which will hopefully provide inspiration for other energy materials.

Backflow, the temporary reversal of discharge at the outlet of a lake, is an important mechanism controlling flow and transport in many connected river–lake systems. This study used statistical methods to examine long-term variations and primary causal factors of backflow from the Yangtze River to a laterally connected, large floodplain lake (Poyang Lake, China). Additionally, the effects of backflow on the lake hydrology were explored using a physically based hydrodynamic model and a particle-tracking model. Although backflow into Poyang Lake occurs frequently, with an average of 16 backflow events per year, and varies greatly in magnitude between years, statistical analysis indicates that both the frequency and magnitude of backflow reduced significantly during 2001–2010 relative to the previous period of 1960–2000. The ratio of Poyang Lake catchment inflows to Yangtze River discharge can be used as an indication of the daily occurrence of backflow, which is most likely to occur during periods when this ratio is lower than 5%. Statistical analysis also indicates that the Yangtze River discharge is the main controlling factor of backflow during July to October, rather than catchment inflows to the lake. Hydrodynamic modelling reveals that, in general, backflow disturbs the normal northward water flow direction in Poyang Lake and transports mass ~20 km southward into the lake. The effects of backflow on flow direction, water velocities and water levels propagate to virtually its upstream extremity. The current study represents a first attempt to explore backflow and causal factors for a highly dynamic floodplain lake system. An improved understanding of Poyang Lake backflow is critical for guiding future strategies to manage the lake, its water quality and ecosystem value, given proposals to modify the lake–river connectivity. Copyright © 2016 John Wiley & Sons, Ltd.

A variety of infrared applications rely on semiconductor superlattices, including, notably, the realization of high-power, compact quantum cascade lasers. Requirements for atomically smooth interface and limited lattice matching options set high technical standards for fabricating applicable heterostructure devices. The semiconductor twinning superlattice (TSL) forms in a single compound with periodically spaced twin boundaries and sharp interface junctions and can be grown with convenient synthesis methods. Therefore, employing semiconductor TSL may facilitate the development of optoelectronic applications related to superlattice structures. Here, it is shown that InAs TSL nanowires generate inter-sub-band transition channels due to the band projection and the Bragg-like electron reflection. The findings reveal the physical mechanisms of inter-sub-band transitions in TSL structure and suggest that TSL structures are promising candidates for mid-infrared optoelectronic applications.

Abrupt temperature reduction in winter wheat at either autumn seedling stage prior to vernalisation or early spring crown stage can cause severe crop damage and reduce production. Many studies have reported the physiological and molecular mechanisms underlying cold acclimation in winter wheat by comparing it with spring wheat. However, processes associated with abrupt temperature reduction in autumn seedling stage prior to vernalisation in winter wheat are less understood. In this study, physiological and molecular responses of winter wheat seedlings to abrupt low temperature (LT) stress were characterised in the relatively LT-tolerant winter wheat cultivar Shixin 828 by comparing it with the relatively LT-sensitive cultivar Shiluan 02-1 using a combination of physiological, proteomics and biochemical approaches. Shixin 828 was tolerant to abrupt LT stress, while Shiluan 02-1 exhibited high levels of reactive oxygen species (ROS) and leaf cell death. Significant increases in relative abundance of antioxidant-related proteins were found in Shixin 828 leaves, which correlate with observed higher antioxidant enzyme activity in Shixin 828 compared to Shiluan 02-1. Proteomics analysis also indicated that carbohydrate metabolism-related proteins were more abundant in Shiluan 02-1, correlating with observed accumulation of soluble sugars in Shiluan 02-1 leaves. Amino acid analysis revealed a strong response to LT stress in wheat leaves. A negative effect of exogenous sucrose on LT tolerance was also found. This study indicates that high ROS scavenging capacity and high abundance of photosynthesis-related proteins might play a role in winter wheat response to abrupt LT stress. In contrast, excess accumulation of soluble sugars might be disadvantageous for LT tolerance in the wheat cultivar Shiluan 02-1.

Multiple confined-state transitions within surface quantum dots deposited on In 0.35 Ga 0.65 As template grown on GaAs (311)B substrate, as well as signals from all other relevant portions of the samples including buried QDs, In 0.35 Ga 0.65 As template, and GaAs-related layers, at 77 K, were obtained in a piezomodulation reflectance spectroscopy (PzR) study. The measured transition energies were accurately determined using a Gaussian lineshape fit based on the reference of PL results. Four factors caused the large energy shift (larger than 400 meV) of confined states within SQDs compared to the buried QDs.