We propose an efficient, accurate method to integrate the basins of attraction of a smooth function defined on a general discrete grid and apply it to the Bader charge partitioning for the electron charge density. Starting with the evolution of trajectories in space following the gradient of charge density, we derive an expression for the fraction of space neighboring each grid point that flows to its neighbors. This serves as the basis to compute the fraction of each grid volume that belongs to a basin (Bader volume) and as a weight for the discrete integration of functions over the Bader volume. Compared with other grid-based algorithms, our approach is robust, more computationally efficient with linear computational effort, accurate, and has quadratic convergence. Moreover, it is straightforward to extend to nonuniform grids, such as from a mesh-refinement approach, and can be used to both identify basins of attraction of fixed points and integrate functions over the basins.

Spherical SiO2 particles have been successfully coated with YVO4:Eu3+ phosphor layers through a Pechini sol−gel process. The resulted YVO4:Eu3+@SiO2 core−shell phosphors were characterized by X-ray diffraction (XRD), Fourier-transform IR spectroscopy, scanning electron microscopy, X-ray photoelectron spectra, transmission electron microscopy, UV/vis absorption spectra, general and time-resolved photoluminescence spectra, as well as kinetic decays. The XRD results demonstrate that the YVO4:Eu3+ layers begin to crystallize on the SiO2 particles after annealing at 400 °C, and the crystallinity increases with raising the annealing temperature. The obtained core−shell phosphors have perfect spherical shape with narrow size distribution (average size ca. 500 nm), nonagglomeration, and smooth surface. The thickness of the YVO4:Eu3+ shells on SiO2 cores could be easily tailored by varying the number of deposition cycles (60 nm for two deposition cycles). The Eu3+ shows a strong photoluminescence (PL) (dominated by 5D0−7F2 red emission at 617 nm) due to an efficient energy transfer from vanadate groups to Eu3+. The energy transfer process was further studied by the time-resolved emission spectra as well as kinetic decay curves of Eu3+ upon excitation into the VO4 3- ion. The PL intensity of Eu3+ increases with raising the annealing temperature and the number of coating cycles, and optimum polyethylene glycol concentration in the precursor solution was determined to be 0.08 g/mL for obtaining the strongest emission of Eu3+.

Soft wearable electronics for underwater applications are of interest, but depend on the development of a waterproof, long-term sustainable power source. In this work, we report a bionic stretchable nanogenerator for underwater energy harvesting that mimics the structure of ion channels on the cytomembrane of electrocyte in an electric eel. Combining the effects of triboelectrification caused by flowing liquid and principles of electrostatic induction, the bionic stretchable nanogenerator can harvest mechanical energy from human motion underwater and output an open-circuit voltage over 10 V. Underwater applications of a bionic stretchable nanogenerator have also been demonstrated, such as human body multi-position motion monitoring and an undersea rescue system. The advantages of excellent flexibility, stretchability, outstanding tensile fatigue resistance (over 50,000 times) and underwater performance make the bionic stretchable nanogenerator a promising sustainable power source for the soft wearable electronics used underwater.

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Changes in endocardial pressure (EP) have important clinical significance for heart failure patients with impaired cardiac function. As a vital parameter for evaluating cardiac function, EP is commonly monitored by invasive and expensive cardiac catheterization, which is not feasible for long-term and continuous data collection. In this work, a miniaturized, flexible, and selfpowered endocardial pressure sensor (SEPS) based on triboelectric nanogenerator (TENG), which is integrated with a surgical catheter for minimally invasive implantation, is reported. In a porcine model, SEPS is implanted into the left ventricle and the left atrium. The SEPS has a good response both in low-and high-pressure environments. The SEPS achieves the ultrasensitivity, real-time monitoring, and mechanical stability in vivo. An excellent linearity (R 2 = 0.997) with a sensitivity of 1.195 mV mmHg −1 is obtained. Furthermore, cardiac arrhythmias such as ventricular fibrillation and ventricular premature contraction can also be detected by SEPS. The device may promote the development of miniature implantable medical sensors for monitoring and diagnosis of cardiovascular diseases.

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Sub‐micrometer‐sized tube junctions and dendrites of conducting polyaniline (e.g., see Figure) and polypyrrole have been synthesized through a self‐assembly process for the first time. It is shown that the monomer–dopant micelles act as templates for the self‐assembly of sub‐micrometer‐sized tubes, while the interactions among the polymer chains supply the driving force for micelle aggregation and the formation of junctions and dendrites.

No abstract