A Study on Improving the Efficacy of Nanoparticle-Based Photothermal Therapy: From Nanoscale to Micron Scale to Millimeter Scale

Photothermal therapy based on nanoparticles is a promising method for cancer treatment. However, there are still many limits in practical application. During photothermal therapy, improving therapeutic effect is contradictory to reducing overheating in healthy tissues. We should make the temperature distribution more uniform and reduce the damage of healthy tissue caused by overheating. In the present work, we develop a simple computational method to analyze the temperature distribution during photothermal therapy at three levels (nanoscale, micron scale, and millimeter scale), and investigate the effects of nanoparticle size, volume fraction, light intensity, and irradiation shape on temperature distribution. We find that it is difficult to achieve good therapeutic effect just by adjusting the volume fraction of nanoparticles and light intensity. To achieve good therapeutic effect, we propose a new irradiation shape, spot array light. This method can achieve a better temperature distribution by easily regulating the positions of spots for the tumor with a large aspect ratio or a small one. In addition, the method of irradiation with spot array light can better reduce the overheating at the bottom and top of the tumor than the full-coverage light or others such as ring light. This theoretical work presents a simple method to investigate the effects of irradiation shape on therapy and provides a far more controlled way to improve the efficacy of photothermal therapy

Controllable transition between optical bistability and multistability in graphene/dielectric/graphene structure

We theoretically investigated the controllable transition between optical bistability and multistability in graphene/dielectric/graphene structure for TE and TM polarizations. We show such a transition strongly depends on the Fermi energy of graphene, and thus, it can be controlled by adjusting the gate voltage applied on the graphene. In addition, we also show that the transition can be tuned by changing the thickness and permittivity of the dielectric layer, or by varying the wavelength and the incident angle of the input light. Furthermore, three S-type curves appear in our studied structure, which result in quadristability. Our results may find potential applications in optoelectronic devices

Theory for optical activity in monolayer black phosphorus under external magnetic field

We derive an analytical model for calculating the optical activity in monolayer black phosphorus under an external magnetic field. By optimizing the parameters, the circular dichroism can be comparable to that in previously reported chiral metamaterials in a broad angle range. Besides, the optical activity including the circular dichroism, the circular conversion dichroism and the circular birefringence can be tuned almost linearly via changing the applied magnetic field magnitude. These results show that our proposed model would possess potential applications in polarization optics, stereochemistry, and molecular biology

Thermal emission of one-dimensional conjugated photonic crystals heterojunction embedded with graphene

By means of characteristic matrix method, we make a theoretical investigation on the properties of thermal emission from one-dimensional conjugated photonic crystals heterojunction embedded with graphene. We find that the emissivity plots show sharp spectral peaks and narrow antenna-like angular lobes which show the excellent temporal coherence and spatial coherence. By optimizing the parameters, a close-to-unity emissivity can be achieved in our proposed structure. Furthermore, we demonstrate that the emissivity peak wavelength and emissivity values can be tuned by changing the chemical potential of graphene layer and the center wavelength of conjugated photonic crystals. The study shows that our proposed structure may find great application in infrared spectrometers and infrared gas sensors

Angle-insensitive mid-infrared photonic bandgap in one-dimensional photonic crystal containing single-material semiconductor hyperbolic metamaterial layers

Based on the phase variation compensation theory, we realize an angle-insensitive mid-infrared photonic bandgap (PBG) in a one-dimensional photonic crystal (1DPC) containing single-material semiconductor hyperbolic metamaterial layers. Under proper design, the bandwidth of the angle-insensitive (omnidirectional) mid-infrared PBG can reach 2.438 \upmu \hbox {m}. The designed 1DPC is a simple single-material system composed of undoped and doped InAs, which can be fabricated by the molecular beam epitaxy technology under the current experimental conditions. Besides, the angle-insensitive property of the designed mid-infrared PBG is quite robust against the layer thickness. This broadband angle-insensitive mid-infrared PBG would possess potential applications for mid-infrared quantum cascade lasers, mid-infrared gas detectors, mid-infrared photothermal imaging, and protein analysis

China National Lung Cancer Screening Guideline with Low-dose Computed Tomography (2018 version)

Background and objective Lung cancer is the leading cause of cancer-related death in China. The results from a randomized controlled trial using annual low-dose computed tomography (LDCT) in specific high-risk groups demonstrated a 20% reduction in lung cancer mortality. The aim of tihs study is to establish the China National lung cancer screening guidelines for clinical practice. Methods The China lung cancer early detection and treatment expert group (CLCEDTEG) established the China National Lung Cancer Screening Guideline with multidisciplinary representation including 4 thoracic surgeons, 4 thoracic radiologists, 2 medical oncologists, 2 pulmonologists, 2 pathologist, and 2 epidemiologist. Members have engaged in interdisciplinary collaborations regarding lung cancer screening and clinical care of patients with at risk for lung cancer. The expert group reviewed the literature, including screening trials in the United States and Europe and China, and discussed local best clinical practices in the China. A consensus-based guidelines, China National Lung Cancer Screening Guideline (CNLCSG), was recommended by CLCEDTEG appointed by the National Health and Family Planning Commission, based on results of the National Lung Screening Trial, systematic review of evidence related to LDCT screening, and protocol of lung cancer screening program conducted in rural China. Results Annual lung cancer screening with LDCT is recommended for high risk individuals aged 50-74 years who have at least a 20 pack-year smoking history and who currently smoke or have quit within the past five years. Individualized decision making should be conducted before LDCT screening. LDCT screening also represents an opportunity to educate patients as to the health risks of smoking; thus, education should be integrated into the screening process in order to assist smoking cessation. Conclusion A lung cancer screening guideline is recommended for the high-risk population in China. Additional research , including LDCT combined with biomarkers, is needed to optimize the approach to low-dose CT screening in the future