Passive imaging through inhomogeneous scattering media.

According to the atmospheric scattering model (ASM), the object signal's attenuation diminishes exponentially as the imaging distance increases. This imposes limitations on ASM-based methods in situations where the scattering medium one wish to look through is inhomogeneous. Here, we extend ASM by taking into account the spatial variation of the medium density, and propose a two-step method for imaging through inhomogeneous scattering media. In the first step, the proposed method eliminates the direct current component of the scattered pattern by subscribing to the estimated global distribution (background). In the second step, it eliminates the randomized components of the scattered light by using threshold truncation, followed by the histogram equalization to further enhance the contrast. Outdoor experiments were carried out to demonstrate the proposed method.

Fabrication and evaluation of bone morphogenetic protein-2 microspheres coated black phosphorus nanosheets@polylactic-glycolic acid copolymers scaffold: A multifunctional antibacterial photothermal scaffold for bone regeneration.

Clinical bone defects are often caused by high energy injury and are easily complicated by bacterial infection. An ideal bone repair material should promote bone regeneration and prevent bacterial infection. In this study, a multifunctional photothermal scaffold was developed: bone morphogenetic protein-2 (BMP-2)/polylactic-glycolic acid copolymers (PLGA) microspheres were prepared by a double emulsion method and then coated on the scaffolds prepared using a mixture of black phosphorus nanosheets (BPs) and PLGA, to form BMP-2@BPs scaffolds. The structural and photothermal properties of the composite scaffolds were characterized. The BMP-2@BPs scaffolds demonstrated good biocompatibility in both in vitro and in vivo experiments. The BMP-2@BPs scaffolds promoted osteogenic differentiation through a combination of BMP-2 release and upregulation of the expression of heat shock proteins by the radiation of near-infrared (NIR) light, which further upregulated the expression of osteogenesis-related genes. In addition, BPs demonstrated antibacterial effects under the mediation of NIR, which is beneficial for the prevention of clinical bacterial infections. In summary, the BMP-2@BPs scaffold was a multifunctional photothermal scaffold that could accelerate bone regeneration and act against bacteria. This study provides a new perspective for the treatment of bone defects and infectious bone defects.