Natural systems are inextricably affected by noise. Within recent decades, the manner in which noise affects the collective behavior of self-organized systems, specifically, has garnered considerable ...interest from researchers and developers in various fields. To describe the collective motion of multiple interacting particles, Vicsek et al. proposed a well-known self-propelled particle (SPP) system, which exhibits a second-order phase transition from disordered to ordered motion in simulation; due to its non-equilibrium, randomness, and strong coupling nonlinear dynamics, however, there has been no rigorous analysis of such a system to date. To decouple systems consisting of deterministic laws and randomness, we propose a general method which transfers the analysis of these systems to the design of cooperative control algorithms. In this study, we rigorously analyzed the original Vicsek model under both open and periodic boundary conditions for the first time, and developed extensions to heterogeneous SPP systems (including leader-follower models) using the proposed method. Theoretical results show that SPP systems switch an infinite number of times between ordered and disordered states for any noise intensity and population density, which implies that the phase transition indeed takes a nontraditional form. We also investigated the robust consensus and connectivity of these systems. Moreover, the findings presented in this paper suggest that our method can be used to predict possible configurations during the evolution of complex systems, including turn, vortex, bifurcation, and flock merger phenomena as they appear in SPP systems.
Neuromorphic computing consisting of artificial synapses and neural network algorithms provides a promising approach for overcoming the inherent limitations of current computing architecture. ...Developments in electronic devices that can accurately mimic the synaptic plasticity of biological synapses, have promoted the research boom of neuromorphic computing. It is reported that robust ferroelectric tunnel junctions can be employed to design high‐performance electronic synapses. These devices show an excellent memristor function with many reproducible states (≈200) through gradual ferroelectric domain switching. Both short‐ and long‐term plasticity can be emulated by finely tuning the applied pulse parameters in the electronic synapse. The analog conductance switching exhibits high linearity and symmetry with small switching variations. A simulated artificial neural network with supervised learning built from these synaptic devices exhibited high classification accuracy (96.4%) for the Mixed National Institute of Standards and Technology (MNIST) handwritten recognition data set.
Ferroelectric tunnel junctions are utilized to design robust electronic synapses with high performance. Nonvolatile multilevel conductance states with excellent retention property are achieved through gradual ferroelectric domain switching. A simulated artificial neural network with supervised learning exhibits classification accuracy of 96.4% for the MNIST handwritten data set.
Significance Mechanisms are zero-energy motions that are key to the operation of mechanical devices, from windshield wipers to robotic arms. We built and studied chain-like mechanisms of coupled ...rigid rotors that are topologically protected, which means that they are not affected by smooth changes in material parameters like their quantum analogues. These prototypes are examples of mechanical structures that we dub topological metamaterials. Their mechanical excitations are nonlinear solitary waves which are topologically protected and yet tunable by changing the geometry of the unit cell. Although the left and right edges of the sample are equivalent in terms of local constraint counting, the solitary waves can start propagating only from the edge singled out by the topological polarization of the chain.
Graphene-based nanomaterials, such as graphene oxide (GO) and reduced graphene oxide (rGO), have shown great potentials in drug delivery and photodynamic/photothermal therapy due to their featured ...structure and physicochemical properties. In recent years, their antibacterial potentials have also been exploited. The commonly recognized antibacterial mechanisms include sharp edge-mediated cutting effect, oxidative stress and cell entrapment. This antibacterial activity is very important for human health. As we know, infection with the pathogenic bacteria, especially the drug-resistant ones, is a great threat to human lives. Thus, the development of the antibiotics-independent and drug-free antibacterial agents is of great importance and significance. Graphene-based nanomaterials are a kind of such antibacterial agents. An insight into their properties and antibacterial mechanisms is necessary before they are developed into real products. Herein, we provide a comprehensive understanding of the antibacterial application of graphene-based nanomaterials via summarizing their antibacterial activities against some typical microbial species and discussing their unique mechanisms. In addition, the side-effects and problems in using these nanomaterials are also discussed.
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Abstract
In the quest for emerging in-sensor computing, materials that respond to optical stimuli in conjunction with non-volatile phase transition are highly desired for realizing bioinspired ...neuromorphic vision components. Here, we report a non-volatile multi-level control of VO
2
films by oxygen stoichiometry engineering under ultraviolet irradiation. Based on the reversible regulation of VO
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films using ultraviolet irradiation and electrolyte gating, we demonstrate a proof-of-principle neuromorphic ultraviolet sensor with integrated sensing, memory, and processing functions at room temperature, and also prove its silicon compatible potential through the wafer-scale integration of a neuromorphic sensor array. The device displays linear weight update with optical writing because its metallic phase proportion increases almost linearly with the light dosage. Moreover, the artificial neural network consisting of this neuromorphic sensor can extract ultraviolet information from the surrounding environment, and significantly improve the recognition accuracy from 24% to 93%. This work provides a path to design neuromorphic sensors and will facilitate the potential applications in artificial vision systems.
Hydrogen peroxide (H
2
O
2
) is a versatile and environmentally friendly oxidant with a wide range of industrial and household applications. In recent years, the decentralization of H
2
O
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...production through the two-electron oxygen reduction reaction (ORR) has emerged as an attractive alternative to the well-established anthraquinone process. And of the many electrocatalysts developed for the two-electron ORR to produce H
2
O
2
, metal-free carbon catalysts (MFCCs) have received extensive attention due to their cost-effectiveness and natural abundance. Based on this, this review will provide an in-depth overview into MFCC design and fabrication with an emphasis on porosity control, heteroatom doping, oxygen functionalization, defect engineering and organic-inorganic interface engineering. This review will also discuss and analyze the interplays between these factors in terms of MFCC catalytic activity and selectivity towards H
2
O
2
production. Furthermore, major technical challenges are presented, and future research directions are proposed to guide further development towards practical application.
Recent progress in the development of metal-free carbon catalysts for ORR to H
2
O
2
.
Considering that the human brain uses ≈1015 synapses to operate, the development of effective artificial synapses is essential to build brain‐inspired computing systems. In biological synapses, the ...voltage‐gated ion channels are very important for regulating the action‐potential firing. Here, an electrolyte‐gated transistor using WO3 with a unique tunnel structure, which can emulate the ionic modulation process of biological synapses, is proposed. The transistor successfully realizes synaptic functions of both short‐term and long‐term plasticity. Short‐term plasticity is mimicked with the help of electrolyte ion dynamics under low electrical bias, whereas the long‐term plasticity is realized using proton insertion in WO3 under high electrical bias. This is a new working approach to control the transition from short‐term memory to long‐term memory using different gate voltage amplitude for artificial synapses. Other essential synaptic behaviors, such as paired pulse facilitation, the depression and potentiation of synaptic weight, as well as spike‐timing‐dependent plasticity are also implemented in this artificial synapse. These results provide a new recipe for designing synaptic electrolyte‐gated transistors through the electrostatic and electrochemical effects.
An electrolyte‐gated transistor using WO3 with a unique tunnel structure to successfully emulate the synaptic functions of both short‐term and long‐term plasticity is proposed. Short‐term plasticity is mimicked with the help of electrolyte ion dynamics under low gate bias, and the long‐term plasticity is realized via proton insertion in WO3 under high gate bias.
So far, there were no reports on circular RNA (circRNA) expression profiles in the differentiation of human umbilical cord–derived mesenchymal stem cells (hUCMSCs) into cardiomyocyte‐like cells ...induced by 5‐aza. In this study, hUCMSCs were isolated from umbilical cords and induced with 5‐aza for 14 days. Immunofluorescence staining, real‐time reverse transcription polymerase chain reaction (RT‐PCR), and western blot of cardiac troponin I and α‐sarcomeric actin on hUCMSCs between Days 14 and 0 were performed. The expression profile of circRNAs was analyzed by microarray and validated with RT‐PCR. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes analyses were performed to identify the functions of differentially expressed genes and related pathways. The connections between circRNAs and microRNAs were explored by using Cytoscape. The results showed that a total of 226 circRNAs were calculated as differentially expressed during the differentiation. Among them, 127 were upregulated and 99 were downregulated. We selected circRNAs that were upregulated by more than five‐fold and downregulated by more than three‐fold. Ultimately, 74 differentially expressed circRNAs that were highly conserved on Day 14 after induction compared to Day 0 were identified. Among them, 41 were upregulated and 33 were downregulated. Four upregulated circRNAs (circRNA_01536, circRNA_04411, circRNA_09169, and circRNA_09905) and four downregulated circRNAs (circRNA_00699, circRNA_01183, circRNA_01978, and circRNA_16804) were randomly confirmed by RT‐PCR. GO analysis suggested a number of cell proliferation and differentiation related physiological processes and pathways, such as the Wnt signaling pathway and others. Network analysis uncovered three potential key circRNAs, that is, circRNA_05432, circRNA_08441, and circRNA_01536.
1.
This is the first study to investigate the circular RNA (circRNA) expression in the differentiation of human umbilical cord–derived mesenchymal stem cells (hUCMSCs) into cardiomyogenically induced cells.
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A unique expression profle of circRNAs was found in the differentiation of hUCMSCs into cardiomyogenically induced cells.
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Network analysis uncovered three potential key circRNAs, that is, circRNA_05432, circRNA_08441, and circRNA_01536 and circRNA‐hsa‐miR‐3620‐5p–mediated network may play a critical role in the differentiation of hUCMSCs into cardiomyogenically induced cells.
This study was performed to investigate the clinical efficacy of percutaneous kyphoplasty (PKP) for vertebral compression fractures with different bone mineral densities (BMD).
We performed a ...retrospective analysis of 232 patients with single-segment vertebral compression fractures who underwent PKP. Patients were divided into the normal BMD, osteopenia, and osteoporosis groups according to their average lumbar BMD before surgery. The visual analog scale (VAS) was used to compare differences in pain relief before and after surgery in each group. Corrections of the wedge angle and kyphotic angle before and after surgery were observed using anteroposterior and lateral radiographs and compared among the groups, as was the incidence of bone cement leakage.
Patients were followed up for 6-12 months, with an average follow-up time of 9.12 ± 1.68 months. The VAS score, wedge angle, and kyphotic angle of the three groups of patients decreased significantly at the end of the follow-up (P < 0.05). The changes in VAS score and wedge angle correction in the osteoporosis group were significantly larger than those in the normal BMD and osteopenia groups (P < 0.05). There were no significant differences among the three groups in terms of kyphotic angle correction or bone cement leakage rates (P > 0.05).
PKP has a positive effect on vertebral compression fractures with different BMD, and is especially suitable for osteoporotic vertebral compression fractures.
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