Robust Room Temperature Ferromagnetism In Cobalt Doped Graphene by Precision Control of Metal Ion Hybridization

Graphene-based magnetic materials exhibit novel properties and promising applications in the development of next-generation spintronic devices. Modern synthesis techniques have paved the way to design precisely the local environments of metal atoms anchored onto a nitrogen-doped graphene matrix. Herein, it is demonstrated that grafting cobalt (Co) into the graphene lattice induces robust and stable room-temperature ferromagnetism. These comprehensive experiments and first-principles calculations unambiguously identify that the mechanism for this unusual ferromagnetism is π-d orbital hybridization between Co d_xz and graphene p_z orbitals. Here, it is found that the magnetic interactions of Co–carbon ions are mediated by the spin-polarized graphene p_z orbitals, and room temperature ferromagnetism can be stabilized by electron doping. It is also found that the electronic structure near the Fermi level, which sets the nature of spin polarization of graphene p_z bands, strongly depends on the local environment of the Co moiety. This is the crucial, previously missing, ingredient that enables control of the magnetism. Overall, these observations unambiguously reveal that engineering the atomic structure of metal-embedded graphene lattices through careful d to p orbital interactions opens a new window of opportunities for developing graphene-based spintronics devices.     

Immunostimulatory activity of Lactococcus lactis LM1185 isolated from Hydrangea macrophylla

Food Science and Biotechnology - The lactic acid bacteria, Lactococcus lactis subsp. lactis LM1185 was isolated from Hydrangea macrophylla. Strain LM1185 showed 50.5% of acid tolerance at pH 2.5...     

Tailoring Luminescent Solar Concentrators for High-Performance Flexible Double-Junction III-V Photovoltaics

Despite the remarkable advantages of luminescent solar concentrators (LSCs), their application has not been of interest in ultrahigh efficient photovoltaic modules such as multi-junctions and related two-terminal tandems due to challenging issues limiting the cell capability and impeding the output current. Here type of multi-junction LSC photovoltaics is presented that consists of transfer-printed arrays of InGaP/GaAs solar cells and strategically tailored luminescent waveguides. A coplanar waveguide with the non-self-aligned quantum dot luminophores enables simultaneous absorptions of the directly illuminated solar flux and the indirectly waveguided LSC flux, where cell deployment and luminophore spectrum are systematically tuned for balanced enhancement of the subcell photocurrents. Through systematic comparisons across various LSC configurations supported by both experimental and theoretical quantifications, the power conversion efficiency of flexible modules with InGaP/GaAs cell arrays is improved from 1.67% to 2.22% by the optimal LSC, where the module area is 14.4 times larger than the total cell area. The details of optical and mechanical studies provide a further comprehensive understanding of the suggested approach toward multi-junction LSC photovoltaics.