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Vertically injected thin-film ultraviolet light-emitting diodes operating at 325 and 280nm are demonstrated. Low-temperature AlN interlayers allow crack-free growth of AlxGa1−xN with compositions up to x=0.53 on GaN-on-sapphire templates. The GaN layer allows laser-induced separation of the highly strained epi stack from the sapphire substrate with high yield. Cathode contacts are formed on nitrogen-face AlxGa1−xN (up to x=0.53) and allow vertical injection of current into the active region. Controlled roughening of the nitrogen-face AlxGa1−xN is also demonstrated through photoelectrochemical etching and results in >2.5× light extraction gain for 325 and 280nm devices.

External-stimuli-driven soft actuators overcome several limitations inherent in traditional mechanical-driven technology considering the coming age of flexible robots, which might face harsh working conditions and rigorous multifunctional requirements. However, how to achieve multi-external-stimuli response, fast speed, and precise control of the position and angle of the actuator, especially working in a toxic liquid or vapor environment, still requires long-term efforts. Here, we report a multi-external-stimuli-driven sandwich actuator with aligned carbon nanotubes as the constructive subject, which can respond to various types of liquids (organic solvents), vapor, and solar light. The actuator has an ultrafast response speed (<10 ms) and can accurately adjust the bending angle range from 0° to 180°. Through manipulating the stimuli positions, actuators can be wound into varied turns when simulating a flexible robotic arm. Hence, liquid/vapor/light-driven actuators are able to support diverse programmable motions, such as periodic blooming, gesture variations, caterpillar crawling, toxic surface evading, and bionic phototaxis. We believe that this multifunctional actuator is promising in supporting a complex scenario to complete a variety of tasks in the fields of healthcare, bioengineering, chip technology, and mobile sensors.

Many applications are based on the use of materials with heterogeneous microstructure. Prominent examples are fiber-reinforced composites, multi-phase steels or soft tissue to name only a few. The modeling of structures composed of such materials is suitably carried out at different scales. At the micro scale, the detailed microstructure is taken into account, whereas the modeling at the macro scale serves to include sophisticated structural geometries with complex boundary conditions. The procedure is crucially based on an intelligent bridging between the scales. One of the methods derived for this purpose is the meanwhile well established FE 2 method which, however, leads to a very high computational effort. Unfortunately, this impedes the use of the FE 2 method and similar methodologies for practically relevant problems as they occur e.g. in production or medical technology. The goal of the present paper is to significantly improve computational efficiency by using model reduction. The suggested procedure is very generally applicable. It holds for large deformations as well as for all relevant types of inelasticity. An important merit of the work is the computation of the consistent tangent operator based on the reduced stiffness matrix of the microstructure. In this way a very fast (in most cases quadratic) convergence within the Newton iteration at macro level is achieved.

Over the last decades, the treatment of the large quantities of hypersaline wastewater generated by conventional industries, inland desalination, and fossil‐fueled power plants has been an important economic issue and also an inescapable green issue. Here, we developed a versatile interfacial heating membrane with alternating utilization of electricity or solar energy for hypersaline water treatment. This hierarchical membrane functions both as a separation membrane and an interface heater, which can quickly (<0.1 s) convert electricity or solar energy into heat to evaporate the outermost layer of hypersaline water. For 10 wt% hypersaline water, the freshwater production rate can reach 16.8 kg/m2·h by applying a voltage of 10 V and 1.36 kg/m2·h under 1‐sun illumination. Moreover, it exhibits high electrochemical resistance to corrosion and therefore remains stable tackling hypersaline water (>5 wt%), with a high salt rejection rate of 99.99%. This system shows an efficient desalination strategy that can provide fresh water from brines for agriculture and industry, and even for daily life.