It is well known that tumors have an acidic pH microenvironment and contain a high content of hydrogen peroxide (H 2 O 2 ). These features of the tumor microenvironment may provide physiochemical conditions that are suitable for selective tumor therapy and recognition. Here, for the first time, we demonstrate that a type of graphene oxide nanoparticle (N-GO) can exhibit peroxidase-like activities (i.e., can increase the levels of reactive oxygen species (ROS)) under acidic conditions and catalyze the conversion of H 2 O 2 to ROShydroxyl radicals (HO • ) in the acidic microenvironment in Hela tumors. The concentrated and highly toxic HO • can then trigger necrosis of tumor cells. In the microenvironment of normal tissues, which has a neutral pH and low levels of H 2 O 2 , N-GOs exhibit catalase-like activity (scavenge ROS) that splits H 2 O 2 into O 2 and water (H 2 O), leaving normal cells unharmed. In the recognition of tumors, an inherent redox characteristic of dopamine is that it oxidizes to form dopamine− quinine under neutral (pH 7.4) conditions, quenching the fluorescence of N-GOs; however, this characteristic has no effect on the fluorescence of N-GOs in an acidic (pH 6.0) medium. This pH-controlled response provides an active targeting strategy for the diagnostic recognition of tumor cells. Our current work demonstrates that nanocatalytic N-GOs in an acidic and high-H 2 O 2 tumor microenvironment can provide novel benefits that can reduce drug resistance, minimize side effects on normal tissues, improve antitumor efficacy, and offer good biocompatibility for tumor selective therapeutics and specific recognition.

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Wireless power transfer (WPT) technologies are a major trend for emerging Internet-of-Things (IoT) applications. Because they negate the need for heavy, bulky batteries and can power multiple elements simultaneously, WPT systems enable very compact, ubiquitous IoT wireless devices. However, the realization of high performance, ultra-compact (electrically small) rectennas, i.e., the rectifying antennas that enable mid-range and far-field WPT, is challenging. We present the first electrically small (ka < 0.77) and low profile (0.04 λ0) linearly (LP) and circularly (CP) polarized WPT rectennas at 915 MHz in the IMS band. They are facilitated by the seamless integration of highly efficient rectifiers, i.e., RF signal to DC power conversion circuits, with electrically small Huygens dipole LP and CP antennas. Their optimized prototypes have cardioid, broadside radiation patterns and effective capture areas larger than their physical size. Experimental results validate that they achieve an 89% peak ACto-DC conversion efficiency, effectively confirming that they are ideal candidates for many of the emerging IoT applications. Index Terms-Electrically small rectennas, Huygens radiation pattern, internet-of-things (IoT), rectifier circuits, wireless power transfer.

The accumulation of anthocyanins in leaves and stems of Mikania micrantha improves its adaptability to low-temperature environments during winter in areas where this species is invasive. The accumulation of anthocyanins in M. micrantha causes the plants to exhibit red coloration when encountering low-temperature environments during winter. Many studies have reported that the accumulation of anthocyanins near the plant surface filters light and improves photoprotection. However, the results of this study showed that the main role of anthocyanins accumulation in M. micrantha during winter was to increase both antioxidant capability and tolerance to low temperature. The results showed that the anthocyanin contents were significantly higher in red leaves and stems than in green leaves and stems, with more than 60-fold greater content in red leaves than in green leaves. In addition, the total antioxidant capability was significantly greater in red leaves and stems than in green leaves and stems. After 4°C treatment for 12 h, a large amount of reactive oxygen species accumulated in green leaves and stems, and the maximum photochemical efficiency decreased significantly. Compared with that of the green leaves, the net photosynthetic rate of red leaves was significantly higher. The biomass statistics revealed that the dry matter accumulation of M. micrantha plants with relatively large amounts of anthocyanins was significantly greater than that of plants with relatively low anthocyanin levels during the same period. Our results suggest that the accumulation of anthocyanins during winter is an adaptation strategy of M. micrantha to low winter temperatures.