Vector Exceptional Points with Strong Superchiral Fields.

Exceptional points (EPs), branch points of complex energy surfaces at which eigenvalues and eigenvectors coalesce, are ubiquitous in non-Hermitian systems. Many novel properties and applications have been proposed around the EPs. One of the important applications is to enhance the detection sensitivity. However, due to the lack of single-handed superchiral fields, all of the proposed EP-based sensing mechanisms are only useful for the nonchiral discrimination. Here, we propose theoretically and demonstrate experimentally a new type of EP, which is called a radiation vector EP, to fulfill the homogeneous superchiral fields for chiral sensing. This type of EP is realized by suitably tuning the coupling strength and radiation losses for a pair of orthogonal polarization modes in the photonic crystal slab. Based on the unique modal-coupling property at the vector EP, we demonstrate that the uniform superchiral fields can be generated with two beams of lights illuminating the photonic crystal slab from opposite directions. Thus, the designed photonic crystal slab, which supports the vector EP, can be used to perform surface-enhanced chiral detection. Our findings provide a new strategy for ultrasensitive characterization and quantification of molecular chirality, a key aspect for various bioscience and biomedicine applications.

Mesoporous hydroxyapatite nanoparticles hydrothermally synthesized in aqueous solution with hexametaphosphate and tea polyphenols.

Mesoporous hydroxyapatite (HA) nanoparticles with high surface area have been widely investigated for drug delivery. Herein we report a facile and simple strategy for the preparation of such materials using hexametaphosphate salt as inorganic phosphorus source. In the hydrothermal processing, hexametaphosphate plays an important role in the formation of mesoporous structure. The as-prepared mesoporous HA nanoparticles can be candidates for pH-responsive anticancer drug delivery by using doxorubicin (Dox) as a model drug. Furthermore, modification of these mesoporous HA nanoparticles using tea polyphenols is attempted. The presence of tea polyphenols in the HA synthesis processing result in mesoporous HA nanoparticles with tailored morphology and properties, making them more pH-sensitive for drug delivery. Both hexametaphosphate and tea polyphenols can be potential chemical sources in synthesizing mesoporous HA.

Deposition of calcium phosphate coatings using condensed phosphates (P2O7(4-) and P3O10(5-)) as phosphate source through induction heating.

In present work condensed phosphates (P2O7(4-) and P3O10(5-)) were used as phosphate source in induction heating to deposit calcium phosphate coatings. The phase, morphology, and composition of different phosphate-related coatings were characterized and compared using XRD, FTIR, and SEM analyses. Results showed that P2O7(4-)formed calcium pyrophosphate hydrate coatings with interconnected cuboid-like particles. The as-deposited calcium tripolyphosphate hydrate coating with P3O10(5-) was mainly composed of flower-like particles assembled by plate-like crystals. The bioactivity and cytocompatibility of the coatings were also studied. Moreover, the feasibility of using hybrid phosphate sources for preparing and depositing coatings onto magnesium alloy was investigated.