Dominance hierarchy has a profound impact on animals' survival, health, and reproductive success, but its neural circuit mechanism is virtually unknown. We found that dominance ranking in mice is transitive, relatively stable, and highly correlates among multiple behavior measures. Recording from layer V pyramidal neurons of the medial prefrontal cortex (mPFC) showed higher strength of excitatory synaptic inputs in mice with higher ranking, as compared with their subordinate cage mates. Furthermore, molecular manipulations that resulted in an increase and decrease in the synaptic efficacy in dorsal mPFC neurons caused an upward and downward movement in the social rank, respectively. These results provide direct evidence for mPFC's involvement in social hierarchy and suggest that social rank is plastic and can be tuned by altering synaptic strength in mPFC pyramidal cells.

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Fully degradable poly(L-lactic) acid (PLLA) and lignin blends were prepared using the melt blending method. The impact strength of PLLA was dramatically improved by 52.4% and 36.6% with the addition of 5 wt% and 10 wt% of lignin, respectively. Meanwhile, the Young's modulus was maintained. Polarized optical microscopy (POM) results indicated that lignin served as a nucleating agent for the heterogeneous crystallization of PLLA in blends, which was responsible for the improvement in the impact strength. The introduced lignin also promoted the cold-crystallization of PLLA, which was demonstrated by differential scanning calorimetry (DSC). The blends of PLLA with lignin are considered to be a promising material because of the improved toughness, the full degradability, and the lower price compared with pure PLLA.

Poly(vinyl alcohol) (PVA)/b-tricalcium phosphate (b-TCP, Ca 3 (PO 4 ) 2 ) porous composite, which has potential application in articular cartilage repair, was prepared through thermal foaming using water as both plasticizer and physical blowing agent. The effects of b-TCP content on the foaming behavior, the structure and properties of the porous composites were studied. The results showed that b-TCP could form hydrogen bonds or coordination interaction with PVA and water; with the incorporation of b-TCP, the content of nonfreezable bound water in system increased, the water evaporation reduced, beneficial to the controllable foaming of water. The interactions between PVA-b-TCP led to the enhanced melt viscosity of PVA. Simultaneously, the b-TCP particles in matrix could act as heterogeneous nucleation agent to increase the cell density. When b-TCP content was 7.4 wt %, the porous composite showed the optimal cell structure, i.e., 250 lm average cell size and 87% porosity. The dynamic modulus of the porous composites increased with b-TCP content and showed frequency-dependence. The surface contact angle and permeability of the porous composites varied with b-TCP content, which ranged from 358 to 488 and 11 3 10 214 to 27 3 10 214 m 2 , respectively. V C 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44737.