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Zinc manganese oxide (ZMO) system represents a notable family of mixed transition metal oxides (MTMOs) because of their superiority of the high theoretical capacity, adequacy of natural content, and low cost. However, the methods to match both the reliable synthesis and the designable construction of large-sized two-dimensional (2D) ZMO nanosheets are still considered grand challenges. Herein, we have successfully realized the preparation of 2D ZMO nanosheets with large lateral sizes up to ∼20 μm by simple pyrolysis of 2D metal-organic framework (MOF) nanosheets precursor. The growth mechanism of 2D MOF is proposed to be based on the lamellar micelles formed by polyvinyl pyrrolidone (PVP). The obtained 2D and porous ZMO nanosheets exhibit high specific capacity as well as good rate capability. More importantly, the as-prepared ZMO electrode shows a remarkable capacity increment upon cycling (from 832 mAh g-1 at the 2nd cycle to 1418 mAh g-1 at the 700th cycle, at 1 A g-1). Through simple adjustment of the calcination temperature, the valence state of Mn species in the yielding ZMO samples can be fine-tuned. Through systematic investigation towards these ZMOs containing different Mn species, the extra specific capacity is revealed to be chiefly on account of the arising of the valence state of Mn upon the cycling process. Moreover, it is disclosed that the higher-valent Mn the pristine ZMO contains, the more additional capacity it gains upon cycling. We believe that this work will inspire more detailed analysis on the relationship between the valence state of Mn and extra capacity.

The rapid development of wearable, highly integrated, and flexible electronics has stimulated great demand for on-chip and miniaturized energy storage devices. By virtue of their high power density and long cycle life, micro-supercapacitors (MSCs), especially those with interdigital structures, have attracted considerable attention. In recent years, tremendous theoretical and experimental explorations have been carried out on the structures and electrode materials of MSCs, aiming to obtain better mechanical and electrochemical properties. The high-performance MSCs can be used in many fields, such as energy storage and medical assistant examination. Here, this review focuses on the recent progress of advanced MSCs in fabrication strategies, structural design, electrode materials design and function, and integrated applications, where typical examples are highlighted and analyzed. Furthermore, the current challenges and future development directions of advanced MSCs are also discussed.

This study investigated the effect of fermentation by Lactobacillus plantarum CGMCC 14177 strain on physicochemical properties and morphological characteristics of potato starch. The maximum total amylase and α-amylase production of L. plantarum CGMCC 14177 were 286.8 and 208.1 U/g, respectively. Fermented granules clearly exhibited pocked and dimpled surfaces. The granule properties changed to have a 1.9% increase in relative crystallinity. Overall the starch changed to have slight increases in onset and peak temperature, but resulted decreases of conclusion temperature and enthalpy. Fermentation decreased peak viscosity and breakdown value, while increased trough viscosity, final viscosity, and setback. Further analysis showed that fermentation increased the gel hardness and chewiness of the potato starch, but made little differences in the springiness, cohesiveness and resilience. Collectively, these results provide insight on how Lactobacillus strains can be used to modify the physicochemical properties of potato starch in ways that extend its use in industrial applications.

The unmanned aerial vehicle (UAV) can extend the network coverage and improve the system throughput for 5th generation (5G) communication systems; hence, it receives a lot of attention recently. This paper considers the problem of channel predictive precoding for UAV-enabled cache-assisted B5G multi-input multi-output (MIMO) systems. A novel channel precoder predictor is proposed, in which the prediction is conducted on a non-linear vector space—Grassmannian manifold. The predictor at the receiver utilizes the current and previous channel matrices to solve the precoder at the next time and then feeds it back to the transmitter for precoding. More specifically, two sub-matrices are extracted from the channel right singular matrices and modeled as two points on the Grassmannian manifold. Then, the geodesic between the two points is conducted. Unlike the conventional method in which the tangent vector at the previous point is parallel transported along the geodesic, we predict the next point by use of the geodesic equation directly. We analyze the computational complexity of the proposed method and demonstrate the superiority of the proposed method by comparing with the conventional one. Besides, we adopt a general Ricean channel model in the UAV MIMO system, where both the Kronecker model and Jake’s model are incorporated. The effects of various channel model parameters on the system performance in terms of the chordal error of channel predictor and the optimum step are thoroughly investigated.

In this study, we attempted to fill an important gap that literature has yet to investigate: the characteristics of the 3D printing global industry chain and value chain innovation network. The network characteristics analysis is based on patents and the patent data download from the European Patent Office (EPO) database covering the period from January 1, 1989 to December 31, 2017. The concept of the 3D printing global industry chain and value chain network is defined, then the network model is divided by employing case analysis, and finally the network characteristics are analyzed by using social network analysis. This research enriches the relevant theories of global innovation networks in emerging industries and provides theoretical support for the development of global innovation strategies and policies for the 3D printing industry.

The massive and sustained realization of highly reactive nanometals@carbon scaffold matrix may push forward the further development of next-generation alkaline battery systems. Herein, we put forwa...

An accurate estimator of chirp rate and initial frequency of the linear frequency modulation (LFM) signals based on modified discrete chirp Fourier transform (MDCFT) is investigated in this study. The proposed algorithm consists of two banks, namely coarse search and fine search. The coarse search returns a coarse estimate of the parameter by addressing the maximum MDCFT coefficient of a LFM signal. The coarse estimate is refined by fine search algorithms, including spectrum slices and iterative interpolation methods. Compared to conventional fine search approaches, spectrum slices and iterative interpolation methods are always more efficient because they utilize more prior information about the MDCFT results, thus requiring fewer extra computations. Finally, computer simulations are conducted to evaluate the performance of our algorithms by comparison with the Cramer–Rao lower bound. The proposed estimator shows robust performance for various values of the signal parameters with the addition in the additive white Gaussian noise.

This paper proposes an analytic inverse kinematics computation method for redundant manipulator with S-R-S configuration. Forward kinematics model is built based on traditional D-H modeling approach. The redundancy is decoupled through designing the virtual arm angle parameters and the relationship between arm angle and joint angle is detailed. A complete analytic inverse kinematics equation in position space is obtained, which eliminates the acquisition of joint speed and Jacobian matrix. And the optimal strategy to obtain inverse kinematics under joint limits is designed. The method is verified using robotics toolbox and simulation is made on the ROS platform.

The poor electronic and ionic conductivities restrict the application of Li2ZnTi3O8 (LZTO) especially at high current rates. In this work, LZTO is modified with Li2ZrO3 (LZO) by simply reacting LiNO3 and Zr(NO3)4·5H2O on the surface of the as-prepared LZTO particles to improve the electrochemical performance. The modified LZTO with a LZO/LZTO mass ratio of 0.008 and sintered at 750 °C for 5 h exhibits greatly enhanced rate capabilities (acquiring reversible capacities of 196.1, 175.9, 154.9, 135.1, 109.8, and 223.6 mAh g−1 at 100, 200, 400, 800, 1600, and 100 mA g−1, respectively), and outstanding long-term cyclability (retaining a capacity of 199.2 mAh g−1 after 600 cycles at 500 mA g−1). On the basis of detailed characterizations on structure and composition as well as DFT calculations, the dispersed LZO nanoparticles and LZO coating bridge the LZTO particles to facilitate Li+ migration among the LZTO particles, while the superficial Zr4+ doping in LZTO promotes electron transfer, resulting in the simultaneously ameliorated electronic and ionic conductivities of LZTO, as well as alleviated polarization.

We put forward a facile one-pot hydrothermal strategy to synthesize the MnX2O4(X = Co, Ni) spinel/graphite nanoflakes (GNF) composites. Note that the physical exfoliation toward GNF frees the method from the complex and expensive conventional chemical treatments. The obtained MnCo2O4/GNF (MCO/GNF) and MnNi2O4/GNF (MNO/GNF) exhibit high specific capacitance (1712 F g−1 for MCO/GNF and 1622 F g−1 for MNO/GNF at 1 A g−1) and good cycling performance (almost 80 % capacitance retention after 3500 cycles at 5 A g−1 for both MCO/GNF and MNO/GNF). Furthermore, the asymmetric supercapacitor (ASC) with MCO/GNF or MNO/GNF as positive electrode and rGO as the negative electrode is assembled. The optimized ASC is able to show high energy density up to 22.5 Wh kg−1. Together with the facile synthetic strategy, such good electrochemical performance may promote the spreading of the next-generation energy storage electrodes.

Sodium sulfur (NaS) cell is recognized as a promising candidate for advanced grid-scale large energy storage systems (ESS). In this work, we study the impacts of planar NaS cell container materials on the accumulation of residual stresses in the cell joints and solid electrolyte during the cell assembly and operation processes. Concentration of such thermo-mechanical stress in these vulnerable areas in the modern NaS cells can lead to catastrophic cell failures, which can present a huge challenge for developing large planar NaS cells towards commercial deployment. Here, we employ the finite-element analysis (FEA) computational technique to quantitatively assess the thermo-mechanical stress accumulation using prototype planar NaS cells. Relevant experimental procedures with corresponding thermal cycling conditions for the cell assembly, operation, and maintenance processes are incorporated into the FEA model. The influences of Al alloy (Al3003), stainless steels (STS304 and STS340), and iron-nickel-cobalt superalloy (KOVAR) on the residual stress accumulation are tested and thoroughly discussed. The computation results show that high stress concentration can be developed in the cell joint area. Through the comprehensive computational analysis, it is suggested that applying smaller CTE (less than ∼12 × 10 −6 K −1 ) alloys is necessary to secure the thermo-mechanical stability of NaS cells that can be implemented in a large scale ESS.

Full atomistic molecular dynamics simulations are performed on tetra-sulfides and undoped conjugated polymers pernigraniline base polyaniline (PNB), leucoemeraldine base polyaniline (LEB), poly (3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPY) to investigate the binding effectiveness between polysulfides and polymer binders. The weight ratio between sulfur and binder in lithium–sulfur cells is considered in 1:1 v/v mixture of dioxolane/dimethoxyethane. The simulations reveal that the end group 2 of PNB can effectively bind a lithium tetra-sulfide (i.e. Li2S4) cluster or 2 out of 43 Li2S4 molecules with the effect of solvent. However, repeat units of PNB, LEB, PEDOT and PPY seem ineffective in binding solvated Li2S4 through non-bonded interaction, especially when the concentration of tetra-sulfide/binder in a local domain of the cathode is low. Therefore, polymers with this specific functional group (i.e. the end group 2 of PNB) are suggested to be further studied as potential effective binders to inhibit the shuttle effect of solvated lithium polysulfides. Also, since the solvent has considerable impact on the binding effectiveness between tetra-sulfides and binder, it is suggested to take advantage of the explicit solvation models, such as those built in this work, to predict how other influencing factors affect binding between polysulfides and polymers.

Evolution of domestic wastes into competitive battery materials at less expense is a rational strategy of "killing two birds with one stone", and never better for grid-scale energy-storage utilizations wherein achieving great energy density is less crucial than environmental friendliness and cost. To checkout this concept, we herein select Fe2N, a conductive conversion-type anode for Li-/Na-ion batteries (LIBs/SIBs), as a paradigm study. Rusty/plastic wastes-evolved anodes with a proper tap density of 1.74 g cm−3 are composed of numerous nanoparticles where each Fe2N unit is evenly configured in robust carbon sheath. Such electrodes demonstrate impressive specific capacities under varied areal mass loading ratios of 3∼15 mg cm-2, outstanding rate capabilities and cyclic stability. To judge their promise in practical usage, we successively choose economical LiFePO4 and phase-stable Na3V2(PO4)3 as pairing cathodes to build full-cell LIBs/SIBs. This wastes-to-battery protocol may pave a way to advance practical techniques for sustainable usage beyond.

Poly (lactic-co-glycolic acid) (PLGA) copolymers have been broadly used in controlled drug release applications. Because these polymers are biodegradable, they provide an attractive option for drug delivery vehicles. There are a variety of material, processing, and physiological factors that impact the degradation rates of PLGA polymers and concurrent drug release kinetics. This work is intended to provide a comprehensive and collective review of the physicochemical and physiological factors that dictate the degradation behavior of PLGA polymers and drug release from contemporary PLGA-based drug-polymer products. In conjunction with the existing experimental results, analytical and numerical theories developed to predict drug release from PLGA-based polymers are summarized and correlated with the experimental observations. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1692-1716, 2017.

In different parts of the gastrointestinal tract, the rate of drug release from polyelectrolyte hydrogel tablets is highly affected by variance of ionic concentration. This research aims at revealing clearly how the drug release from a hydrogel matrix is affected by ionic concentration of external solution through the finite element simulation and triphasic mechanism model. The coupled relationship of the motions including the polyelectrolyte hydrogel swelling, the water flow and the ion diffusion, is illustrated in the present work. In order to simulate the drug controlled release from a swollen polyelectrolyte hydrogel carrier, the mathematical model was built on the basis of the multiphasic theory of polyelectrolyte hydrogels. Finally, the reliability of the simulation method was verified qualitatively by experimental results. The results reveal that when the initial concentration of fixed anions of polymer network is higher than the concentration of free anions in the external solution, the drug release rate increases with increasing the ionic concentration of the external solution. The research is helpful for the optimal design of oral drug release in gastrointestinal tract.

The infrared normal spectral emissivity of the oxidized molybdenum was measured during thermal oxidation process, and the integral emissivity was calculated from the data of spectral emissivity. It is found that the surface oxidation has a remarkable effect on the spectral emissivity of molybdenum, and the spectral emissivity curves become more fluctuant with the increase in oxidation time. The integral emissivity grows exponentially with the oxidation time at 773 K, remains almost constant at 823 K, and fluctuates at 873 and 923 K. The X-ray fluorescence spectrometer, the X-ray diffraction, and the scanning electron microscopy were employed to analyze the changes in surface composition and surface morphology. The results show that the most probable reason for the variation of integral emissivity is the change in surface roughness caused by the variation in the size and shape of oxide particle on specimen surface.