A new generation of rocket propellants for deep space exploration, ionic liquid propellants, with long endurance and high stability, is attracting more and more attention. However, a major defect of ionic liquid propellants that restricts their application is the inadequate hypergolic reactivity between the fuel and the oxidant, and this defect results in local burnout and accidental explosions during the launch process. We propose a visualization model to show the features of structure, density, thermal stability, and hypergolic activity for estimating propellant performances and their application abilities. This propellant materials genome and visualization model greatly improves the efficiency and quality of developing high-performance propellants, which benefits the discovery of new advanced functional molecules in the field of energetic materials.
A novel solution is proposed to undertake a frequent task in wireless networks, which is to let all nodes broadcast information to and receive information from their respective one-hop neighboring nodes. The contribution in this paper is twofold. First, as each neighbor selects one message-bearing codeword from its unique codebook for transmission, it is shown that decoding their messages based on a superposition of those codewords through the multiaccess channel is fundamentally a problem of compressed sensing. In the case where each message is designed to consist of a small number of bits, an iterative algorithm based on belief propagation is developed for efficient decoding. Second, to satisfy the half-duplex constraint, each codeword consists of randomly distributed on-slots and off-slots. A node transmits during its on-slots and listens to its neighbors only through its own off-slots. Over one frame interval, each node broadcasts a message to its neighbors and simultaneously receives the superposition of neighbors' signals through its own off-slots and then decodes all messages. The proposed solution fully exploits the multiaccess nature of the wireless medium and addresses the half-duplex constraint at the fundamental level. In a network consisting of Poisson distributed nodes, numerical results demonstrate that the proposed scheme often achieves several times the rate of slotted ALOHA and CSMA with the same packet error rate.Index Terms-Ad hoc network, belief propagation, full duplex, message passing, multiaccess channel, Poisson point process, rapid on-off-division duplex, sparse recovery.
Retrieving historical PM2.5 data is key for evaluating the long-term impacts of PM2.5 on the environment, human health, and climate change. Satellite-based aerosol optical depth has been used to estimate PM2.5, but estimations have largely been undermined by massive missing values, low sampling frequency, and weak predictive capability. Here, using a novel feature engineering approach to incorporate spatial effects from meteorological data, we developed a robust LightGBM model that predicts PM2.5 at an unprecedented predictive capacity on hourly (R2 = 0.75), daily (R2 = 0.84), monthly (R2 = 0.88), and annual (R2 = 0.87) timescales. By taking advantage of spatial features, our model can also construct hourly gridded networks of PM2.5. This capability would be further enhanced if meteorological observations from regional stations were incorporated. Our results show that this model has great potential in reconstructing historical PM2.5 datasets and real-time gridded networks at high spatial-temporal resolutions. The resulting datasets can be assimilated into models to produce long-term reanalysis that incorporates interactions between aerosols and physical processes.
Graphene-based micromotors with an alveolate surface of MnO 2 hydrogen peroxide propelled are described. The micromotors display powerful propulsion in a low fuel level (2.5%), with a speed of over 111¯m s ¹1 , as well as efficient locomotion in biological media such as bovine serum. It has a good motion even in very low levels of the hydrogen peroxide fuel (down to 0.15%), which can compare favorably with Pt. The attractive properties of these new chemical-prepared micromotors hold great promise for biomedical applications.The synthesis of micro-and nanomotors is one of the most exciting research areas in nanotechnology because of their considerable promise for diverse potential applications. 110 The effective propulsion of micro-and nanomotors represents a great challenge and has stimulated great research efforts in recent years. 1115 Particularly, bubble-propelled catalytic micromotors have become highly attractive due to their high power output and very high speed in different media. 8,16 Based on different compositions and structures of micro-and nanomotors, that are capable of moving autonomously in the presence of the corresponding fuels. For example, hydrogen-bubble-propelled polyaniline/Zn microrockets display effective autonomous motion in extreme acidic environments and an ultrafast speed along with attractive capabilities including guided movement and directed cargo transport. 17 Based on the aluminumwater reaction, hydrogen bubble-propelled AlGa/Ti motors can move at a remarkable speed. 18 We also reported hydrogen-bubblepropelled seawater-driven Janus Mg-based micromotors, which utilize macrogalvanic corrosion and chloride pitting corrosion processes. 9 Very recently, Wang and co-workers reported catalytic Ir/SiO 2 Janus micromotors powered by extremely low concentrations of hydrazine. 19 A zone of high N 2 , H 2 , and NH 3 concentrations is generated at the Ir surface, resulting in the efficient autonomous propulsion of Janus micromotors. Through the decomposition of hydrogen peroxide on a catalytic surface of micro-and nanomotors, the oxygen-bubble will be produced and power the micro-and nanomotors forward. 8,20 However, these hydrogen peroxide powered micromotors commonly require noble metals, such as Pt, as the chemical fuels that rely on at least 0.2% hydrogen peroxide for their operation. 16,21 Sanchez et al. have reported the utility of an enzyme as the catalyst to decompose H 2 O 2 and propel nanomotors. 22 Manganese dioxide (MnO 2 ) has been receiving growing attention due to its low-cost, abundance, and environmentally friendly properties. Recently, Pumera reported MnO 2 -based bubble-powered micromotors by using H 2 O 2 fuel. 23 These autonomous bubble-propelled MnO 2 micromotors show good motion. However, the fuel level is very high (over 12%). Herein, we demonstrate "sandwich"-like MnO 2 /graphene micromotors with MnO 2 petal nanosheets homogeneously anchored to each side of the graphene. The MnO 2 /graphene micromotors have a high specific surface (about 100.1 m 2 g ¹1 ) leading to t...
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