Chemical Structure and Shape Enhance MR Imaging-Guided X-ray Therapy Following Marginative Delivery.

Ineffective site-specific delivery has seriously impeded the efficacy of nanoparticle-based drugs to a disease site. Here, we report the preparation of three different shapes (sphere, scroll, and oblate) to systematically evaluate the impact of the marginative delivery on the efficacy of magnetic resonance (MR) imaging-guided X-ray irradiation at a low dose of 1 Gy. In addition to the shape effect, the therapeutic efficacy is investigated for the first time to be strongly related to the structure effect that is associated with the chemical activity. The enhanced particle-vessel wall interaction of both the flat scroll and oblate following margination dynamics leads to greater accumulation in the lungs, resulting in superior performance over the sphere against lung tumor growth and suppression of lung metastasis. Furthermore, the impact of the structural discrepancy in nanoparticles on therapeutic efficacy is considered. The tetragonal oblate reveals that the feasibility of the charge-transfer process outperforms the orthorhombic scroll and cubic sphere to suppress tumors. Finally, surface area is also a crucial factor affecting the efficacy of X-ray treatments from the as-prepared particles.

Widely tunable semiconductor lasers with three interferometric arms.

We present a comprehensive study for a new three-branch widely tunable semiconductor laser based on a self-imaging, lossless multi-mode interference (MMI) coupler. We have developed a general theoretical framework that is applicable to all types of interferometric lasers. Our analysis showed that the three-branch laser offers high side-mode suppression ratios (SMSRs) while maintaining a wide tuning range and a low threshold modal gain of the lasing mode. We also present the design rules for tuning over the dense-wavelength division multiplexing grid over the C-band.

Physical model for high indium content InGaN/GaN self-assembled quantum dot ridge-waveguide lasers emitting at red wavelengths (λ ~ 630 nm).

We present a physical model for recently demonstrated high indium content self-assembled In0.4Ga0.6N/GaN quantum dot (QD)-based ridge-waveguide lasers emitting at red wavelengths. The strain distribution in the QD is calculated using linear elastic theory with the application of shrink-fit boundary condition at the InGaN/GaN material interface, and the electronic states are evaluated using a single-band effective mass Hamiltonian. A Schrödinger-Poisson self-consistent solver is used to describe the effect of charge screening under current injection. Our theoretical result shows a good match to the measured Hakki-Paoli gain spectrum. Combining the calculated gain spectrum and cavity properties, we have developed a device-level simulation to successfully explain the electrical and optical characteristics of this specific laser. Possible solutions to improving the device performance have been explored.

Detailed model for the In0.18Ga0.82N/GaN self-assembled quantum dot active material for λ = 420 nm emission.

We present a comprehensive model for In(0.18)Ga(0.82)N/GaN self-assembled quantum dot (QD) active material. The strain distribution in the QD structure is studied using linear elastic theory with the application of the shrink-fit boundary condition at the material interface. Subsequent calculations also predict the strain-induced quantum-confined Stark effect (QCSE). Under carrier injection, the overall effect of band bending and charge screening is studied by solving the Schrödinger and Poisson equations self-consistently. The optical gain spectrum of the InGaN/GaN QD active material is calculated based on the electronic states solved from the Schrödinger-Poisson equation, and both the calculated material gain peak and emission wavelength agree well with the measured experimental data.

Comprehensive model of 1550 nm MEMS-tunable high-contrast-grating VCSELs.

A comprehensive theoretical model for the long-wavelength micro-electro-mechanical-tunable high-contrast-grating vertical-cavity surface-emitting lasers is presented. Our band structure model calculates the optical gain and spontaneous emission of the InGaAlAs quantum well active region. The grating reflectivity and the cavity resonance condition are investigated through optical modeling. Correlating the results with the electrostatic model for the micro-electro-mechanical system, we accurately predict the measurements on the voltage-contolled lasing wavelength. Furthermore, our calculated temperature-dependent wavelength-tunable light output vs. current (L-I) curves show excellent agreement with experiment.