The driving force for the metallic lithium formation in solid electrolytes, such as the cubic Li7La3Zr2O12 (c-LLZO), is still puzzling, considering the large band gap of c-LLZO and the preference of ...Li being ionic in oxides. In this paper, density functional theory (DFT) calculations were performed to investigate the ability of the pore surfaces to trap excess electrons, which is essential to Li nucleation tendency. Two interlayer materials were also studied, tetragonal LLZO (t-LLZO) and Li2PO2N (atomic layer deposited LiPON). It was found that excess electrons would be trapped, either around the La atoms on the surface of c-LLZO or dispersed on the surface of t-LLZO. It is also thermodynamically favorable for the excess electrons on La3+ to reduce Li+. In contrast, the excess electrons were located underneath the surface in Li2PO2N, making it hard to reduce Li+. Thus the surfaces in c-LLZO provide a possible electron pathway for metallic Li formation, and the t-LLZO interlayer observed at the Li/c-LLZO interface would not stop Li dendrites due to its similar Li nucleation tendency as c-LLZO. Furthermore, we propose that an interlayer of Li2PO2N at the Li/c-LLZO interface would be efficient and defect tolerant to suppress Li dendrite formation.
•The driving force of the formation of Li dendrite in solid electrolytes is investigated.•Li nucleation tendency on pore surfaces is determined by DFT calculations.•c-LLZO and t-LLZO can trap excess electrons on the pore surfaces.•Li2PO2N pore surface cannot trap excess electrons.•Li2PO2N interlayer coating is proposed to prevent Li-dendrite growth.
Abstract
High-speed railway aerodynamics is the key basic science for solving the bottleneck problem of high-speed railway development. This paper systematically summarizes the aerodynamic research ...relating to China’s high-speed railway network. Seven key research advances are comprehensively discussed, including train aerodynamic drag-reduction technology, train aerodynamic noise-reduction technology, train ventilation technology, train crossing aerodynamics, train/tunnel aerodynamics, train/climate environment aerodynamics, and train/human body aerodynamics. Seven types of railway aerodynamic test platform built by Central South University are introduced. Five major systems for a high-speed railway network—the aerodynamics theoretical system, the aerodynamic shape (train, tunnel, and so on) design system, the aerodynamics evaluation system, the 3D protection system for operational safety of the high-speed railway network, and the high-speed railway aerodynamic test/computation/analysis platform system—are also introduced. Finally, eight future development directions for the field of railway aerodynamics are proposed. For over 30 years, railway aerodynamics has been an important supporting element in the development of China’s high-speed railway network, which has also promoted the development of high-speed railway aerodynamics throughout the world.
Maintaining the physical contact between the solid electrolyte and the electrode is important to improve the performance of all-solid-state batteries. Imperfect contact can be formed during cell ...fabrication and will be worsened due to cycling, resulting in degradation of the battery performance. In this paper, the effect of imperfect contact area was incorporated into a 1-D Newman battery model by assuming the current and Li concentration will be localized at the contacted area. Constant current discharging processes at different rates and contact areas were simulated for a film-type Li|LiPON|LiCoO2 all-solid-state Li-ion battery. The capacity drop was correlated with the contact area loss. It was found at lower cutoff voltage, the correlation is almost linear with a slope of 1; while at a higher cutoff voltage, the dropping rate is slower. To establish the relationship between the applied pressure and the contact area, Persson's contact mechanics theory was applied, as it uses self-affined surfaces to simplify the multi-length scale contacts in all-solid-state batteries. The contact area and pressure were computed for both film-type and bulk-type all-solid-state Li-ion batteries. The model is then used to suggest how much pressures should be applied to recover the capacity drop due to contact area loss.
Abstract
It is a crucial issue for enterprises to resolve environmental protection‐related institutional pressure along with the implementation of strict environmental policies and the enhancement of ...public environmental awareness. Thus, in this study, we surveyed 312 firms in the Yangtze River Delta of China to investigate the relationship among institutional pressure, green value co‐creation, and firm performance by applying a moderated mediation model. Results indicate that institutional pressure positively affects both green value co‐creation and firm performance, whereas green value co‐creation also has a positive effect on firm performance. Furthermore, green value co‐creation mediates the relationship between institutional pressure and firm performance. However, organizational inertia moderates the mediating effect of green value co‐creation on the correlation between institutional pressure and firm performance. These findings enhance our understanding of the relationship among institutional pressure, green value co‐creation, and firm performance, as well as providing implications for further research and practice.
For several decades, there has been considerable interest in marine‐derived long chain n‐3 fatty acids (n‐3 LCPUFAs) due to their outstanding health benefits. n‐3 LCPUFAs can be found in nature ...either in triglycerides (TAGs) or in phospholipid (PL) form. From brain health point of view, PL n‐3 is more bioavailable and potent compared to n‐3 in TAG form, as only PL n‐3 is able to cross the blood–brain barrier and can be involved in brain biochemical reactions. However, PL n‐3 has been ignored in the fish oil industry and frequently removed as an impurity during degumming processes. As a result, PL products derived from marine sources are very limited compared to TAG products. Commercially, PLs are being used in pharmaceutical industries as drug carriers, in food manufacturing as emulsifiers and in cosmetic industries as skin care agents, but most of the PLs used in these applications are produced from vegetable sources that contain less (without EPA, DPA, and DHA) or sometimes no n‐3 LCPUFAs. This review provides a comprehensive account of the properties, structures, and major sources of marine PLs, and provides focussed discussion of their relationship to brain health. Epidemiological, laboratory, and clinical studies on n‐3 LCPUFAs enriched PLs using different model systems in relation to brain and mental health that have been published over the past few years are discussed in detail.
For real applications of all‐solid‐state batteries (ASSBs) to be realized, understanding and control of the grain boundaries (GBs) are essential. However, the in‐depth insight into the atomic‐scale ...defect stabilities and transport of ions around GBs is still far from understood. Here, a first‐principles investigation on the promising garnet Li7La3Zr2O12 (LLZO) solid electrolyte (SE) GBs is carried out. The study reveals a GB‐dependent behavior for the Li‐ion transport correlated to the diffusion network. Of particular note, the Σ3(112) tilt GB model exhibits a quite high Li‐ion conductivity comparable to that in bulk, and a fast intergranular diffusion, contrary to former discovered. Moreover, the uncovered preferential electron localization at the Σ3(112) GB leads to an increase in the electronic conductivity at the GB, and the Li accumulation at the coarse GBs is revealed from the negative Li interstitial formation energies. These factors play important roles in the dendrite formation along the GBs during Li plating in the LLZO|Li cell. These findings suggest strategies for the optimization of synthesis conditions and coating materials at the interface for preventing dendrite formation. The present comprehensive simulations provide new insights into the GB effect and engineering of the SE in ASSBs.
An atomic‐scale investigation on the grain boundary (GB) of a Li7La3Zr2O12 solid electrolyte based on the first‐principles method is carried out. A diffusion behavior of Li‐ion dependent on the GB structure is revealed. A Li nucleation phenomenon is observed at the GB with poor contact, which probably determines the dendrite formation.
Feedback loops in gene regulatory networks play pivotal roles in governing functional dynamics of cells. Systems approaches demonstrated characteristic dynamical features, including multistability ...and oscillation, of positive and negative feedback loops. Recent experiments and theories have implicated highly interconnected feedback loops (high-feedback loops) in additional nonintuitive functions, such as controlling cell differentiation rate and multistep cell lineage progression. However, it remains challenging to identify and visualize high-feedback loops in complex gene regulatory networks due to the myriad of ways in which the loops can be combined. Furthermore, it is unclear whether the high-feedback loop structures with these potential functions are widespread in biological systems. Finally, it remains challenging to understand diverse dynamical features, such as high-order multistability and oscillation, generated by individual networks containing high-feedback loops. To address these problems, we developed HiLoop, a toolkit that enables discovery, visualization, and analysis of several types of high-feedback loops in large biological networks.
HiLoop not only extracts high-feedback structures and visualize them in intuitive ways, but also quantifies the enrichment of overrepresented structures. Through random parameterization of mathematical models derived from target networks, HiLoop presents characteristic features of the underlying systems, including complex multistability and oscillations, in a unifying framework. Using HiLoop, we were able to analyze realistic gene regulatory networks containing dozens to hundreds of genes, and to identify many small high-feedback systems. We found more than a 100 human transcription factors involved in high-feedback loops that were not studied previously. In addition, HiLoop enabled the discovery of an enrichment of high feedback in pathways related to epithelial-mesenchymal transition.
HiLoop makes the study of complex networks accessible without significant computational demands. It can serve as a hypothesis generator through identification and modeling of high-feedback subnetworks, or as a quantification method for motif enrichment analysis. As an example of discovery, we found that multistep cell lineage progression may be driven by either specific instances of high-feedback loops with sparse appearances, or generally enriched topologies in gene regulatory networks. We expect HiLoop's usefulness to increase as experimental data of regulatory networks accumulate. Code is freely available for use or extension at https://github.com/BenNordick/HiLoop .
In complex electromagnetic interference environments, adaptive sidelobe cancellation is an effective measure to suppress radar active jamming. It adopts spatial filtering technology, which can ...effectively suppress sidelobe interference1. In this paper, the basic theory of adaptive sidelobe cancellation system is introduced, and two commonly used algorithms are briefly introduced. In practical application, the cancellation effect decreases due to many factors. In order to improve the performance of adaptive sidelobe cancellation, this paper proposes a method of adaptive acquisition of interference sampling data, and uses this method to simulate and analyze the collected jamming data. Now the device function is becoming more and more powerful, and the system hardware platform has also developed rapidly. Compared with the traditional method, this new interference data sampling method has certain advantages and is of practical significance. At the same time, the problems that should be paid attention to in engineering implementation are put forward.
Summary
Reversible transitions between epithelial and mesenchymal cell states are a crucial form of epithelial plasticity for development and disease progression. Recent experimental data and ...mechanistic models showed multiple intermediate epithelial–mesenchymal transition (EMT) states as well as trajectories of EMT underpinned by complex gene regulatory networks. In this review, we summarize recent progress in quantifying EMT and characterizing EMT paths with computational methods and quantitative experiments including omics‐level measurements. We provide perspectives on how these studies can help relating fundamental cell biology to physiological and pathological outcomes of EMT.
AbstractObjectiveTo measure the association of China’s universal two child policy, announced in October 2015, with changes in births and health related birth characteristics.DesignNational, ...descriptive before-and-after comparative study.SettingEvery county in 28 of 31 provinces of mainland China.ParticipantsBirths included in two national databases: 67 786 749 births from county level monthly aggregated data between January 2014 and December 2017; and 31 786 279 deliveries from individual level delivery information records between January 2015 and December 2017.Main outcome measuresMonthly mean number of births and mean proportion of multiparous mothers and mothers aged 35 and over, preterm deliveries, and caesarean deliveries.ResultsThe study had two phases: the baseline period (up to and including June 2016, nine months after the policy announcement) and the effective period (from July 2016 to December 2017). The estimated number of additional births attributable to the new policy between July 2016 and December 2017 was 5.40 million (95% confidence interval 4.34 to 6.46). The monthly mean percentage of multiparous mothers and mothers aged 35 and over increased by 9.1 percentage points (95% confidence interval 6.4 to 11.7) and 5.8 percentage points (5.2 to 6.4), respectively. This increase in older mothers, however, was not associated with a concurrent increase in the overall rate of preterm birth. The monthly mean caesarean delivery rate among multiparous mothers increased by 1.2 percentage points (0.8 to 1.6) from 39.7% to 40.9%, and decreased by 3.0 percentage points (−3.5 to −2.5) among nulliparous mothers from 39.6% to 36.6%.ConclusionsSince its announcement in October 2015, the universal two child policy has been associated with a rise in births in China and with changes in health related birth characteristics: women giving birth have been more likely to be multiparous, and more likely to be aged 35 and over. No evidence of concurrent worsening outcomes (that is, premature births) was seen.
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