A tunable perfect absorber based on a black phosphorus/bowtie shaped cavity hybrid metasurface.

The practical application of black phosphorus (BP) is limited by its low absorption characteristics. In this work, we propose a perfect absorber based on a BP and bowtie shaped cavity, which has high tunability and excellent optical performance. This absorber effectively increases the light-matter interaction and achieves perfect absorption by using a monolayer BP and a reflector to form a Fabry-Perot cavity. We study the influence of structural parameters on the absorption spectrum and realize the adjustment of frequency and absorption in a certain range. Applying an external electric field on the surface of BP by electrostatic gating, we can change its carrier concentration to control its optical properties. In addition, we can flexibly tune the absorption and Q-factor by varying the polarization direction of incident light. This absorber has promising applications in optical switches, sensing, and slow light, which provides a new perspective for the practical application of BP and a foundation for future research, offering possibilities for more applications.

Combination of color Doppler ultrasound and CT for diagnosing breast cancer.

OBJECTIVE: This research aimed to estimate the diagnostic value of the combination of color Doppler ultrasound (CDU) and computed tomography (CT) in breast cancer (BC). METHODS: Among the 90 BC patients treated in our hospital from May 2018 to December 2020, 43 were examined by CDU before surgery and they served as the control group (CG), while the other 47 were examined with CDU and CT and were considered as the research group (RG). Lesions were confirmed as BC by postoperative pathological examination. The diagnosis rate for BC in the two groups was recorded, and the diagnostic value was analyzed by the receiver operating characteristic (ROC) curve. The imaging features were compared. The diagnostic accuracy for T, N and M stages was evaluated, as well as the diagnosis rate for axillary lymph node metastasis (ALNM) in BC. RESULTS: The RG showed a higher diagnosis rate for BC (P<0.05) and sharper imaging features, with an area under the curve (AUC) of 0.843 (P<0.05). The diagnostic accuracy for T, N and M stages and the diagnosis rate for ALNM in the RG were higher than those in the CG (P<0.05 for each comparison). CONCLUSION: The combination of CDU and CT has a high diagnostic value in BC, which is worthy of clinical promotion.