Autonomous indication of electrical degradation in polymers.

Dielectric polymers are ubiquitous as electrical insulation in electronic devices and electrical systems. Electrical degradation of dielectric polymers tends to initiate catastrophic failure of numerous devices and systems, but its detection and early warning remain challenging. Here we report a general material strategy that signals the electrical degradation of dielectric polymers by autonomously presenting a visually discernible warning in the form of a pronounced colour change. This colour change is induced by the chromogenic response of molecular indicators blended with the polymer, which are chemically activated by the oxygen radicals generated in situ during the electrical degradation of the polymer. We unveil that the structural degradation and electrical properties of the dielectric polymer are quantitatively correlated with the colour difference. Such a chromogenic process is autonomous without the need of human intervention or other external energy, thus offering the convenience to lower or even eliminate the risk of dielectric failure.

An intelligent wearable artificial pancreas patch based on a microtube glucose sensor and an ultrasonic insulin pump.

In order to improve the living standards of diabetes patients and reduce the negative health effects of this disease, the medical community has been actively searching for more effective treatments. In recent years, an artificial pancreas has emerged as an important approach to managing diabetes. Despite these recent advances, meeting the requirements for miniaturized size, accurate sensing and large-volume pumping capability remains a great challenge. Here, we present a novel miniaturized artificial pancreas based on a long microtube sensor integrated with an ultrasonic pump. Our device meets the requirements of achieving both accurate sensing and high pumping capacity. The artificial pancreas is constructed based on a long microtube that is low cost, painless and simple to operate, where the exterior of the microtube is fabricated as a glucose sensor for detecting diabetes and the interior of the microtube is used as a channel for delivering insulin through an ultrasonic pump. This work successfully achieved closed-loop control of blood glucose and treatment of diabetes in rats. It is expected that this work can open up new methodologies for the development of microsystems, and advance the management approach for diabetes patients.

Microcapsule-Based Autonomous Self-Healing of Electrical Damage in Dielectric Polymers Induced by In Situ Generated Radicals.

Dielectric polymers are playing important roles in electrical and electronic industries. However, aging under high electric stress is a main threat to the reliability of polymers. In this work, we demonstrate a self-healing method for electrical tree damage based on radical chain polymerization, which is initiated by in situ radicals that are generated during electrical aging. Acrylate monomers contained in microcapsules will be released and flow into hollow channels after the capsules are punctured by electrical trees. Autonomous radical polymerization of the monomers will heal the damaged regions, which is triggered by radicals resulting from polymer chain scissions. After optimizing the healing agent compositions by evaluating their polymerization rate and dielectric properties, the fabricated self-healing epoxy resins showed effective recovery from treeing in multiple aging-healing cycles. We also expect the great potential of this method to heal tree defects autonomously without the need to switch off operating voltages. This novel self-healing strategy will shed light on building smart dielectric polymers with its broad applicability and online healing competence.

Overexpression of adrenomedullin (ADM) alleviates the senescence of human dental pulp stem cells by regulating the miR-152/CCNA2 pathway.

The limitation of human dental pulp stem cells (DPSCs), which have potential application value in regenerative medicine, is that they are prone to age in vitro. Studies have shown adrenomedullin (ADM) is believed to promote the proliferation of human DPSCs, but whether it can also affect aging remains to be investigated. A lentivirus vector was used to construct human DPSCs overexpressing ADM. Senescence tests were carried out on cells of the 7th and 15th passage. Transcriptome analysis was conducted to analyze microRNA expression regulation changes after human DPSCs overexpressed ADM. H2O2 induced the aging model of human DPSCs, and we examined the mechanism of recovery of aging through transfection experiments with miR-152 mimic, pCDH-CCNA2, and CCNA2 siRNA. Overexpression of ADM significantly upregulated the G2/M phase ratio of human DPSCs in natural passage culture (P = 0.001) and inhibited the expression of p53 (P = 0.014), P21 WAF1 (P = 0.015), and P16 INK4A (P = 0.001). Decreased ROS accumulation was observed in human DPSCs during long-term natural passage (P = 0.022). Transcriptome analysis showed that miR-152 was significantly upregulated during human DPSC senescence (P = 0.001) and could induce cell senescence by directly targeting CCNA2. Transfection with miR-152 mimic significantly reversed the inhibitory effect of ADM overexpression on p53 (P = 0.006), P21 WAF1 (P = 0.012), and P16 INK4A (P = 0.01) proteins in human DPSCs (H2O2-induced). In contrast, pCDH-CCNA2 weakened the effect of the miR-152 mimic, thus promoting cell proliferation and antiaging. ADM-overexpressing human DPSCs promote cell cycle progression and resist cellular senescence through CCNA2 expression promotion by inhibiting miR-152.

Neural Network-Based Routing Energy-Saving Algorithm for Wireless Sensor Networks.

With the evolvement, standards have changed, mobile Internet technology has also been upgraded, and it has also driven the development of smart objects mobile. With the continuous development of smart objects mobile, the bottleneck of small node size and low battery energy storage has not been solved in the end, which makes the research of wireless sensor network energy-saving technology become the focus, and the improvement of routing technology is an effective way to improve energy-saving technology. From the data transmission energy consumption of smart objects mobile, the routing algorithm of smart objects mobile is discussed and analyzed and the classical representative LEACH is the object of in-depth research. Routing algorithms can easily and reliably process network data and make the network work well and are widely used in highly secure military systems and smaller commercial networks. Aiming at these deficiencies, a corresponding improved algorithm is proposed, and it is tested through simulation and specific experiments to verify the correctness and the system's reliability. The SMPSO-BP algorithm converges when the number of iterations is about 600, which is earlier than the LEACH algorithm and the improved LEACH algorithm, so the SMPSO-BP algorithm is due to the other two algorithms. In the wireless sensor network routing energy consumption experiment, in addition, the SMPSO-BP algorithm uses less energy than the other two methods. Therefore, the energy-saving algorithm under the neural network data fusion mechanism is still feasible.

Defect-targeted self-healing of multiscale damage in polymers.

Self-healing materials capable of restoring functionality in response to damage are expected to gain prolonged service lifespan. Yet the ability to repair damage of diverse length scales which is demanded for the survival of highly capricious and uncontrolled damage modes has not been demonstrated with current self-healing approaches. Herein the repeatable self-healing of multiscale damage ranging from nanometer to millimeter is achieved in thermoplastic polymers through defect-targeted heating and welding. The key to the ability to deal with multiscale damage is the automatic and targeted transport and assembly of superparamagnetic nanoparticles toward the defect site. This allows the concentrated nanoparticles to deliver a high heating power under an oscillating magnetic field and locally fuse the matrix, whereas the overall dimensional integrity of the material is well preserved. Moreover, as the polymer melt drives progressively into the open volume of the crack, the nanoparticles keep migrating with the edge of the crack until the fractured portions are united. The cracking-healing cycle can be repeated 100 times with a constantly high healing efficiency above 95%. This work sheds light on the new design of self-healing materials where the ability to deal with complex damage modes represents a key merit to prompt real-world applications.