In recent years, nanocomposites based on various nano-scale carbon fillers, such as carbon nanotubes (CNTs), are increasingly being thought of as a realistic alternative to conventional smart ...materials, largely due to their superior electrical properties. Great interest has been generated in building highly sensitive strain sensors with these new nanocomposites. This article reviews the recent significant developments in the field of highly sensitive strain sensors made from CNT/polymer nanocomposites. We focus on the following two topics: electrical conductivity and piezoresistivity of CNT/polymer nanocomposites, and the relationship between them by considering the internal conductive network formed by CNTs, tunneling effect, aspect ratio and piezoresistivity of CNTs themselves, etc. Many recent experimental, theoretical and numerical studies in this field are described in detail to uncover the working mechanisms of this new type of strain sensors and to demonstrate some possible key factors for improving the sensor sensitivity.
Abstract
A self-supporting Co
3
O
4
/graphene hybrid film has been constructed via vacuum filtration of Co(OH)
2
nanosheet and graphene, followed by a two-step thermal treatment. Within the hybrid ...film, Co
3
O
4
nanoparticles with size of 40~60 nm uniformly
in-situ
grew on the surface of graphene, forming a novel porous and interleaved structure with strong interactions between Co
3
O
4
nanoparticles and graphene. Such fascinating microstructures can greatly facilitate interfacial electron transportation and accommodate the volume changes upon Li ions insertion and extraction. Consequently, the binder-less hybrid film demonstrated extremely high reversible capacity (1287.7 mAh g
−
1
at 0.2 A g
−
1
), excellent cycling stability and rate capability (1110 and 800 mAh g
−
1
at 0.5 and 1.0 A g
−
1
, respectively).
Compared to conventional electronic composites, polymer nanocomposites containing carbon nanotubes (CNT) have superior electrical properties. In the research, a highly efficient numerical method used ...to calculate the resistivity of the CNT/polymer composite is presented based on an integrated three-dimensional (3D) statistical resistor network model (RNM) which incorporates the tunneling effect between neighboring nanotubes. By this 3D RNM, the electrical properties of a composite brick in which a certain number of CNT are distributed randomly can be calculated. However, to guarantee the convergence of calculation, the number of CNTs must be larger than a threshold, and this may cause the calculation to be very time-consuming. In order to improve the computational efficiency, a modified calculation scheme using coarse-net model (CNM) is proposed. According to the scheme, a composite brick containing a large number of CNTs is divided into an array of cells, each of which has a limited volume and contains a small number of CNTs. These cells are assumed to be connected in a 3D network whereby each cell is considered as a resistor and its resistance can be calculated by the original integrated 3D model efficiently. Statistically, the effective resistance of such a resistor network that can be evaluated by Kirchhoff’s current law is the same as the resistance of the composite brick. The comparison between the conventional RNM and the CNM proves that the latter can improve the computational efficiency tremendously.
Establishing techniques to efficiently and nondestructively access the intracellular milieu is essential for many biomedical and scientific applications, ranging from drug delivery, to electrical ...recording, to biochemical detection. Cell penetration using nanoneedle arrays is currently a research focus area because it not only meets the increasing therapeutic demands of cell modifications and genome editing, but also provides an ideal platform for tracking long‐term intracellular information. Although the precise mechanism driving membrane penetration by nanoneedle arrays is still unclear, the low cytotoxicity, wide range of delivered materials, diverse cell type targets, and simple material structures of nanoneedle arrays make these splendid platforms for cell access. Here, the recent progress in this field is reviewed by examining device architectures and discussing mechanisms for nanoneedle penetration, and the major studies demonstrating the most general applicability of nanoneedle arrays, typical methodologies to access the intracellular environment using nanoneedles with spontaneous or assisted penetration modes, as well as biosafety aspects are presented. This review should be valuable for deeply understanding the materials fabrication principles, device designs, cell penetration methodologies, biosafety aspects, and application strategies of nanoneedle array‐based systems that are of crucial importance for the development of future practical biomedical platforms.
1D nanoneedle arrays have emerged as a powerful and multifunctional nanoplatform for cellular manufacturing and interrogation. Here, recent developments in nanoneedle arrays for cellular applications are summarized from the following aspects: device architectures, mechanisms for nanoneedle penetration, typical methodologies to intracellular access using nanoneedles with spontaneous or assisted penetration modes, as well as biosafety.
The mammalian eye consists of several layers of pigmented tissues that contain melanin. The eye is a unique organ for pigment cell research because one can isolate and compare melanosomes from ...different tissues and embryonic origins. Retinal, iris and ciliary pigment epithelial cells are derived from the neural ectoderm, more specifically from the extremity of the embryonic optical cup, which is also the origin of the retina. In contrast, the pigment‐generating cells in the choroid and in the stroma of the iris and ciliary body, uveal melanocytes, are developed from the neural crest, the same origin as the melanocytes in skin and hair. This review examines the potential functions of ocular melanin in the human eye. Following a discussion of the role of melanins in the pigment epithelium and uveal melanocytes, three specific topics are explored in detail—photo‐screening protective effects, biophysical and biochemical protective effects, and the biologic and photobiologic effects of the two main classes of melanins (generally found as mixtures in ocular melanosomes)—eumelanin and pheomelanin.
Coronavirus disease 2019 (COVID‐19) is a newly emerging infectious disease. Our understanding of the clinical characteristics of liver damage and the relationship with disease severity in COVID‐19 is ...still limited. To investigate the serum hepatic enzyme activities in different phenotypes of COVID‐19 patients, evaluate their relationship with the illness severity and analyze the correlation of glycyrrhizin treatment and abnormal liver enzyme activities, one hundred and forty‐seven patients with COVID‐19 were enrolled in a retrospective study that investigated hepatic dysfunction. Liver alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactic dehydrogenase (LDH), Y‐glutamyl transferase (GGT), superoxide dismutase (SOD), and alkaline phosphatase (ALP) were analyzed in these patients. Patients with diammonium glycyrrhizinate (DG) treatment were further investigated. Of the 147 patients, 56 (38.1%) had abnormal ALT activity and 80 (54.4%) had abnormal AST activity. The peak of abnormal hepatic enzyme activities occurred at 3 to 6 days after on admission. Serum AST and LDH levels were elevated, while the SOD level was decreased in severe and critical patients, compared with mild cases. DG treatment may alleviate the abnormal liver enzyme activities in non‐critical COVID‐19 patients. Abnormal liver functions may be observed in patients with COVID‐19, and were associated with SARS‐CoV‐2‐induced acute liver damage. Glycyrrhizin treatment may be an effective therapeutic approach for the outcome of abnormal hepatic enzyme activities in severe COVID‐19 cases. Serum hepatic enzyme tests may reflect the illness severity and should be monitored.
Vehicle 3D extents and trajectories are critical cues for predicting the future location of vehicles and planning future agent ego-motion based on those predictions. In this paper, we propose a novel ...online framework for 3D vehicle detection and tracking from monocular videos. The framework can not only associate detections of vehicles in motion over time, but also estimate their complete 3D bounding box information from a sequence of 2D images captured on a moving platform. Our method leverages 3D box depth-ordering matching for robust instance association and utilizes 3D trajectory prediction for re-identification of occluded vehicles. We also design a motion learning module based on an LSTM for more accurate long-term motion extrapolation. Our experiments on simulation, KITTI, and Argoverse datasets show that our 3D tracking pipeline offers robust data association and tracking. On Argoverse, our image-based method is significantly better for tracking 3D vehicles within 30 meters than the LiDAR-centric baseline methods.
Abstract Background The efforts to explore and build the structure of good doctor abilities are important because they help improve the quality of education for medical students and better ...standardize the working performance of doctors. However, at present, no worldwide standards for such a structure have been established. In this study, we endeavoured to map the structure of good doctor abilities and identify their effects. Methods With a focus on China, a thematic content analysis was adopted in this study to analyse the personal profiles of 50 widely recognized good doctors. NVivo11 software was used. Results The Structure and Effects of Good Doctor Abilities in China model was proposed, and interpretations were made based on AMO theory. Good doctor abilities fall within six categories: rigorous clinical thinking, skilled in diagnosis and therapy, clinical empathy, continuous learning and innovation, enhancing and sharing experiences, and communication and coordination. These abilities have positive impacts on doctors’ work performances and social benefits by encouraging good behaviours, ultimately promoting the sustainable development of the hospitals where they serve. Conclusions In this study, we established a model of the structure and effects of good-doctor abilities in China and interpreted its mechanism, innovation and theory diversification in “good-doctor” research. Moreover, this study has practical significance because it provides systematic and well-targeted criteria for improving the professionalism of doctors, promoting more good doctor behaviours, providing guidance for regulating doctors’ conduct and providing a reference for medical education and working performance reviews worldwide.
Fabricating hierarchical core-shell nanostructures is currently the subject of intensive research in the electrochemical field owing to the hopes it raises for making efficient electrodes for ...high-performance supercapacitors. Here, we develop a simple and cost-effective approach to prepare CuO@MnO2 core-shell nanostructures without any surfactants and report their applications as electrodes for supercapacitors. An asymmetric supercapacitor with CuO@MnO2 core-shell nanostructure as the positive electrode and activated microwave exfoliated graphite oxide (MEGO) as the negative electrode yields an energy density of 22.1 Wh kg(-1) and a maximum power density of 85.6 kW kg(-1); the device shows a long-term cycling stability which retains 101.5% of its initial capacitance even after 10000 cycles. Such a facile strategy to fabricate the hierarchical CuO@MnO2 core-shell nanostructure with significantly improved functionalities opens up a novel avenue to design electrode materials on demand for high-performance supercapacitor applications.
Titanium matrix composites reinforced by graphene oxide (GO) and carbon nanotube (CNT) were successfully prepared by hot-pressing sintering. The effect of GO content on dispersion and particle size ...of CNT was analysed. In addition, the microstructure, phase structure and mechanical properties of Ti/GO-CNT composites were characterized, and the synergistic strengthening mechanism was investigated. The results show that dispersion of CNT can be significantly improved by adding GO. TiC particles with size of 100–200 nm are formed in situ between matrix and reinforcements. CNT and GO still partly keep an integrated structure after sintering. A significant synergetic effect was observed between GO and CNT that improved the mechanical properties of the composite. The maximum hardness and yield strength of the composite were 771.5 HV and 1387.1 MPa, which is 150% and 74% higher than that of pure Ti when the GO/CNT ratio is 5:1. The synergistic strength enhancement reaches a maximum when GO/CNT ratio is 1:1.
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•The dispersion of carbon nanotubes can be improved by addition of graphene oxide.•Graphene oxide and carbon nanotubes can be used as ideal reinforcements to strengthen the titanium matrix.•A clean and non-equilibrium interface between titanium and carbonaceous nanomaterials was formed.•Synergistic strengthening effect between carbon nanotubes and graphene oxide was obtained.
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