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Photodynamic therapy (PDT) is a promising cancer treatment but has limitations due to its dependence on oxygen and high-power-density photoexcitation. Here, we report polymer-based organic photosensitizers (PSs) through rational PS skeleton design and precise side-chain engineering to generate •O2- and •OH under oxygen-free conditions using ultralow-power 808 nm photoexcitation for tumor-specific photodynamic ablation. The designed organic PS skeletons can generate electron-hole pairs to sensitize H2O into •O2- and •OH under oxygen-free conditions with 808 nm photoexcitation, achieving NIR-photoexcited and oxygen-independent •O2- and •OH production. Further, compared with commonly used alkyl side chains, glycol oligomer as the PS side chain mitigates electron-hole recombination and offers more H2O molecules around the electron-hole pairs generated from the hydrophobic PS skeletons, which can yield 4-fold stronger •O2- and •OH production, thus allowing an ultralow-power photoexcitation to yield high PDT effect. Finally, the feasibility of developing activatable PSs for tumor-specific photodynamic therapy in female mice is further demonstrated under 808 nm irradiation with an ultralow-power of 15 mW cm-2. The study not only provides further insights into the PDT mechanism but also offers a general design guideline to develop an oxygen-independent organic PS using ultralow-power NIR photoexcitation for tumor-specific PDT.

The functionality and reliability of nanoscale multilayer devices and components are influenced by changes in stress and microstructure throughout fabrication, processing, and operation. NiV/B4C multilayers with a d-spacing of 3 nm were prepared by magnetron sputtering, and two groups of annealing experiments were performed. The stress, microstructure, and interface changes in NiV/B4C after annealing were investigated by grazing-incidence X-ray reflectometry (GIXR), grazing-incidence X-ray diffraction (GIXRD), X-ray diffuse scattering, and grazing-incidence small-angle X-ray scattering (GISAXS). The temperature dependence experiments revealed a gradual shift in the multilayer stress from compression to tension during annealing from 70 °C to 340 °C, with the stress approaching near-zero levels between 70 °C and 140 °C. The time-dependent experiments indicated that most of the stress changes occurred within the initial 10 min, which showed that prolonged annealing was unnecessary. Combining the X-ray diffraction and X-ray scattering measurements, it was found that the changes in the thickness, interface roughness, and lateral correlation length, primarily due to crystallization, drove the changes in stress and microstructure. [ABSTRACT FROM AUTHOR]

The effect of a 30% predeformation treatment on the high‐temperature oxidation behavior of 436 stainless steel is investigated by oxidizing it at 900 °C for 100 h in air. After 48 h of oxidation, the undeformed sample primarily exhibits bilayer structures consisting of Cr‐rich oxide and outer Fe oxide, while the predeformed sample predominantly displays a single‐layer structure composed of Cr oxide. The oxidation mechanisms of predeformed and undeformed samples are clarified from the point of recrystallization through oxidation kinetic curves, surface and section micrographs, X‐ray diffraction (XRD), electron probe microanalyzer (EPMA), scanning electron microscope (SEM), energy‐dispersive spectroscopy (EDS), electron backscattered diffraction (EBSD), and line scanning characterization methods. The results show that after 1 h of oxidation, the grain size of the undeformed sample is 34.6 μm, and the grain size of the predeformed sample is 16.0 μm. This reduces the critical content required for the generation of protective Cr oxides and provides more diffusion channels for Cr elements, resulting in the formation of a greater amount of Cr oxides. Cr oxides can inhibit the formation of Fe and Mn oxides, thus delaying the onset of breakaway oxidation and improving its resistance to oxidation. [ABSTRACT FROM AUTHOR]

Triple‐negative breast cancer (TNBC) is endowed with a highly aggressive nature that results in distant metastases and high recurrence rates, yet limited success is realized in traditional chemotherapy. Activatable photosensitizers (PSs) may provide an effective and non‐invasive strategy to induce TNBC cell death in a precise way by offering stimuli‐responsive reactive oxygen species (ROS). However, the toxicity of ROS is often mitigated and even devitalized by the instinctive behavior of ROS resistance in TNBC cells. To address this issue, herein a small molecular self‐assembly nano‐prodrug is presented to co‐deliver an activatable PS and ROS resistance inhibitor. In TNBC cells, the overexpressed glutathione can disassemble the nano‐prodrug, thereby releasing ROS resistance inhibitor and activating the PS for photodynamic therapy and fluorescence imaging. A hybrid membrane coating‐assisted nanoparticle formation strategy is further demonstrated for efficient inhibition of tumor growth and distant metastases on both subcutaneous and orthotopic TNBC mice models. [ABSTRACT FROM AUTHOR]

The strong polarization effects and abundant surface states in III-nitrides result in a tunable electric field, modifying the absorption/emission by changing the band structure. Thus, the mechanism of the electric field and the absorption/emission is crucial for future optical logic devices. Here, we propose to extract the information from the absorption/emission edge by numerical simulations. The simulations show that the increase in the field strength would red-shift the spectrum as well as decrease the slope of the edge for both the uniform and non-uniform field. For numerical simulations, we also provide the lower limit of the quantum states to be simulated from Wentzel–Kramers–Brillouin approximation. Then three GaN samples with different n values are analyzed, and the results validate our methods in two ways. On the one hand, the nonuniform field is shown to fit the experimental absorption better at higher n, which is in accordance with previous studies. On the other hand, the reasonable bandgap Eg at zero doping level and the bandgap-renormalization coefficient are obtained. This work would deepen the understanding of the absorption/emission influenced by the electric field and pave the way for numerical analysis of the edge. [ABSTRACT FROM AUTHOR]

Carrier diffusion properties, including the diffusion length, diffusion coefficient, and carrier lifetime are important for photonic devices. In nitride semiconductors, there are many microscopic structures, which have a strong influence on carrier diffusion. In this paper, a method based on the photo-assisted Kelvin-probe force microscope and the confocal time-resolved photoluminescence spectrum at the same position is developed to map simultaneously the topography and the nanoscale vertical carrier diffusion on the semiconductor surface. On the surface without any dislocations, the hole diffusion length and diffusion coefficient are 161 ± 8 nm and 1.6 ± 0.2 cm2/s, respectively. Near the termination of the dislocation loops on the surface, it can be clearly seen that the diffusion length and diffusion coefficient gradually drop to about 13 ± 5 nm and 0.02 ± 0.01 cm2/s with a spatial resolution of about 100 nm. [ABSTRACT FROM AUTHOR]