Distorted surface regions (5-6 nm) with an unusual layered-like structure on LiMnO cathode material were directly observed after it was cycled (3-4.9 V), indicating a possible spinel-to-layered structural transformation. Formation of these distorted regions severely degrades LiMnO cathode capacity. As we attempt to get a better understanding of the exact crystal structure of the distorted regions, the structural transformation pathways and the origins of the distortion are made difficult by the regions' nanoscopic size. Inspired by the reduction of Mn to Mn in surface electronic structures that might be associated with oxygen loss during cycling, we further investigated the atomic-level surface structure of LiMnO by heat-treatments between 600 and 900 °C in various atmospheres, finding similar surface spinel-to-layered structural transformation only for LiMnO heat-treated in argon atmosphere for a few minutes (or more). Controllable and measurable oxygen loss during heat-treatments result in Mn for charge compensation. The ions then undergo a disproportionation reaction, driving the spinel-to-layered transformation by way of an intermediate LiMnO-like structure. The distortion of the surface regions can be extended to the whole bulk by heat-treatment for 300-600 min, ultimately enabling us to identify the bulk-level structure as layered LiMnO (C2/m). This work demonstrates the critical role of Mn in controlling the kinetics of the structural transformation in spinel LiMnO and suggests heat-treatment in argon as a convenient method to control the surface oxygen loss and consequently reconstruct the atomic-level surface structure.

Detailed investigation of the influence of surface modification using a typical oxide (TiO2) on the electrochemical cycling performance of LiNi0.5Mn1.5O4 at room temperature (25 °C) and elevated temperature (55 °C) is reported.

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Visceral leishmaniasis (VL), one of the deadliest parasitic diseases in the world, causes more than 50,000 human deaths each year and afflicts millions of people throughout South America, East Africa, South Asia, and Mediterranean Region. In 2015 the World Health Organization classified VL as a neglected tropical disease (NTD), prompting concentrated study of the VL epidemic using mathematical and simulation models. This paper reviews literature related to prevalence and prevention control strategies. More than thirty current research works were reviewed and classified based on VL epidemic study methods, including modeling approaches, control strategies, and simulation techniques since 2013. A summarization of these technical methods, major findings, and contributions from existing works revealed that VL epidemic research efforts must improve in the areas of validating and verifying VL mathematical models with real-world epidemic data. In addition, more dynamic disease control strategies must be explored and advanced simulation techniques must be used to predict VL pandemics.

Phishing attack is now a big threat to people's daily life and networking environment. Through disguising illegal URLs as legitimate ones, attackers can induce users to visit the phishing URLs to get private information and other benefits. Effective methods of detecting the phishing websites are urgently needed to alleviate the threats posed by the phishing attacks. As the active learning capability from massive data sets, the neural network is widely used to detect the phishing attacks. However, in the stage of training data sets, many useless and small influence features will trap the neural network model into the problem of over-fitting. This problem usually causes the trained model that cannot effectively detect phishing websites. In order to alleviate this problem, this paper proposes OFS-NN, an effective phishing websites detection model based on the optimal feature selection method and neural network. In the proposed OFS-NN, a new index, feature validity value (FVV), is first introduced to evaluate the impact of sensitive features on the phishing websites detection. Then, based on the new FVV index, an algorithm is designed to select the optimal features from the phishing websites. This algorithm is able to alleviate the over-fitting problem of the underlying neural network to a large extent. The selected optimal features are used to train the underlying neural network, and finally, an optimal classifier is constructed to detect the phishing websites. The experimental results show that the OFS-NN model is accurate and stable in detecting many types of phishing websites. INDEX TERMS Information security, intrusion detection, machine learning, neural network.

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202000190. The search for new high-performance and low-cost cathode materials for Li-ion batteries is a challenging issue in materials research. Commonly used cobalt-or nickel-based cathodes suffer from limited resources and safety problems that greatly restrict their large-scale application, especially for electric vehicles and large-scale energy storage. Here, a novel Li-Mn-O Li-rich cathode material with R m3 symmetry is developed via intralayer Li/Mn disordering in the Mn-layer. Due to the special atomic arrangement and higher R m 3 symmetry with respect to the C2/m symmetry, the oxygen redox activity is modulated and the Li in the Li-layer is preferentially thermodynamically extracted from the crystal structure instead of Li in the Mn-layer. The as-obtained material delivers a reversible capacity of over 300 mAh g −1 at 25 mA g −1 and rate capability of up to 260 mAh g −1 at 250 mA g −1 within 2.0-4.8 V. The excellent performance is attributed to its highly structural reversibility, mitigation of Jahn-Teller distortion, lower bandgap, and faster Li-ion 2D channels during the lithium-ion de/intercalation process. This material is not only a promising cathode material candidate but also raises new possibilities for the design of low-cost and high-performance cathode materials.

IntroductionMesenchymal stem cells (MSCs) transplantation has been demonstrated to be an effective strategy for the treatment of cardiovascular disease. However, the low survival rate of MSCs at local diseased tissue reduces the therapeutic efficacy. We therefore investigated the influence of MicroRNA-378 (miR-378) transfection on MSCs survival and vascularization under hypoxic-ischemic condition in vitro.MethodsMSCs were isolated from bone marrow of Sprague–Dawley rats and cultured in vitro. The third passage of MSCs were divided into the miR-378 group and control group. For the miR-378 group, cells were transfected with miR-378 mimic. Both groups experienced exposure to hypoxia (1% O2) and serum deprivation for 24 hours, using normoxia (20% O2) as a negative control during the process. After 24 hours of reoxygenation (20% O2), cell proliferation and apoptosis were evaluated. Expressions of apoptosis and angiogenesis related genes were detected. Both groups were further co-cultured with human umbilical vein endothelial cells to promote vascular differentiation for another 6 hours. Vascular density was assessed thereafter.ResultsCompared with the control group, MSCs transfected with miR-378 showed more rapid growth. Their proliferation rates were much higher at 72 h and 96 h under hypoxic condition (257.33% versus 246.67%, P <0.01; 406.84% versus 365.39%, P <0.05). Cell apoptosis percentage in the miR-378 group was significantly declined under normoxic and hypoxic condition (0.30 ± 0.10% versus 0.50 ± 0.10%, P <0.05; 0.60 ± 0.40% versus 1.70 ± 0.20%, P <0.01). The miR-378 group formed a larger number of vascular branches on matrigel. BCL2 level was decreased accompanied with an upregulated expression of BAX in the two experimental groups under the hypoxic environment. BAX expression was reduced in the miR-378 group under the hypoxic environment. In the miR-378 group, there was a decreased expression of tumor necrosis factor-α on protein level and a reduction of TUSC-2 under normoxic environment. Their expressions were both downregulated under hypoxic environment. For the angiogenesis related genes, enhanced expressions of vascular endothelial growth factorα, platelet derived growth factor-β and transforming growth factor-β1 could be detected both in normoxic and hypoxic-ischemic conditions.ConclusionMiR-378 transfection could effectively promote MSCs survival and vascularization under hypoxic-ischemic condition in vitro.

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