Formation of Nanofoam carbon and re-emergence of Superconductivity in compressed CaC6

Pressure can tune material's electronic properties and control its quantum state, making some systems present disconnected superconducting region as observed in iron chalcogenides and heavy fermion CeCu2Si2. For CaC6 superconductor (Tc of 11.5 K), applying pressure first Tc increases and then suppresses and the superconductivity of this compound is eventually disappeared at about 18 GPa. Here, we report a theoretical finding of the re-emergence of superconductivity in heavily compressed CaC6. The predicted phase III (space group Pmmn) with formation of carbon nanofoam is found to be stable at wide pressure range with a Tc up to 14.7 K at 78 GPa. Diamond-like carbon structure is adhered to the phase IV (Cmcm) for compressed CaC6 after 126 GPa, which has bad metallic behavior, indicating again departure from superconductivity. Re-emerged superconductivity in compressed CaC6 paves a new way to design new-type superconductor by inserting metal into nanoporous host lattice.Comment: 31 pages, 12 figures, and 4 table

Microglia in the aging brain: relevance to neurodegeneration

Microglia cells are the brain counterpart of macrophages and function as the first defense in the brain. Although they are neuroprotective in the young brain, microglia cells may be primed to react abnormally to stimuli in the aged brain and to become neurotoxic and destructive during neurodegeneration. Aging-induced immune senescence occurs in the brain as age-associated microglia senescence, which renders microglia to function abnormally and may eventually promote neurodegeneration. Microglia senescence is manifested by both morphological changes and alterations in immunophenotypic expression and inflammatory profile. These changes are likely caused by microinvironmental factors, but intrinsic factors cannot yet be completely excluded. Microglia senescence appears to underlie the switching of microglia from neuroprotective in the young brain to neurotoxic in the aged brain. The hypothesis of microglia senescence during aging offers a novel perspective on their roles in aging-related neurodegeneration. In Parkinson's disease and Alzheimer's disease, over-activation of microglia may play an active role in the pathogenesis because microglia senescence primes them to be neurotoxic during the development of the diseases

An AMC Backed Folded Dipole Slot Antenna Based on CMOS Process

A fold dipole slot antenna backed by artificial magnetic conductor (AMC) structure based on a standard 0.18 um CMOS process on chip application is firstly proposed in this paper. Conventional silicon antenna on chip (AoC) suffers from low radiation performance because the most electromagnetic energy is restricted in silicon substrate as surface wave for its high dielectric permittivity. The energy is dissipated as thermal for low resistivity of silicon substrate. AMC constructed by a periodic 6*6 square patch array is adopted as background to improve radiation performance of the proposed folded dipole slot AoC. Gain of the proposed AMC backed AoC is improved about 3.5 dB compared with that of the same AoC without AMC background

A fluid-structure interaction solver for the study of the propulsion of a passively deformed fish fin

The three-dimensional fluid-structure interaction of the flexible fins and/or bodies is common in the swimming of aquatic animals, but accurate and efficient numerical methods for simulating such phenomenon are still limited in literature. In this paper, to investigate the propulsion performance of a caudal peduncle-fin locomotor, which is inspired by a biomimetic robotic caudal fin presented by (Ren et al., 2016), a fluid-structure interaction (FSI) solver is developed by combining our in-house finite volume method based fluid code (Liu et al., 2016) and a three-dimensional structural finite element solver CalculiX (Dhondt, 2004). Their coupling is achieved in a partitioned approach via preCICE (Bungartz et al., 2016), a coupling library for partitioned multi-physics simulations. Two benchmark studies including a flexible beam in the wake of square cylinder and a flapping flexible plate are conducted to validate the proposed multi-physics numerical tool. In the present work, a caudal peduncle-fin swimmer whose biological template is the Bluegill Sunfish is modeled. The model consists of a rigid peduncle and a flexible fin which pitches in a uniform flow. The flexible fin is modeled as a thin plate assigned with non-uniformly distributed stiffness. The numerical results indicate that the compliance has a significant influence on the performance. Under the parameters studied in this work, the medium flexible fin exhibits remarkable efficiency improvement as well as thrust augment, while the least flexible fin shows no obvious difference from the rigid one. However, for the most flexible fin, although the thrust production decreases sharply, the efficiency reaches the maximum value. Similar wake flows between our simulations and the obtained experimental results (Esposito et al., 2012) using digital particle image velocimetry (DPIV) techniques are observed. It is be noted that by non-uniformly distributing the rigidity across the caudal fin, our model is able to replicate some fin deformation patterns observed in both the live fish and the experimental robotic fish