Three etchants are used to synthesize three different Ti3C2Tx (MXene) samples. The difference in chemical components, morphology and surface terminations of Ti3C2Tx and their influences on the ...conductivity, stability and flexibility are comprehensively analyzed. The underlying mechanism is investigated simultaneously. Besides, favorable annealing treatments and storage conditions are also proposed to optimize the properties of Ti3C2Tx.
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•Three typical etchants HF, LiF/HCl, TMAOH are used to synthesize three different Ti3C2Tx (MXene) samples.•The difference in chemical components, morphology and surface terminations of Ti3C2Tx are comprehensively analyzed.•Favorable annealing treatments and storage conditions are also proposed to optimize the properties of Ti3C2Tx.
Two-dimensional transition metal carbides or/and nitrides (MXenes) exhibit great development prospects in energy storage, catalysis, sensing and other fields due to their good properties. However, MXenes obtained from different etching conditions show great discrepancy on their electrical and mechanical properties, which will affect their applications to a certain degree. Unfortunately, few reports have systematically investigated such discrepancy and the underlying mechanism. Herein, three etchants and corresponding subsequent operations were used to synthesize three different Ti3C2Tx (MXene) samples. The difference in chemical components, morphology and surface terminations of Ti3C2Tx and their influences on the conductivity, stability and flexibility were comprehensively analyzed. The underlying mechanism has been investigated simultaneously. Based on this, favorable annealing treatments and storage conditions are also proposed to optimize the properties of Ti3C2Tx, which is believed of great meaning to the practical applications of Ti3C2Tx.
A high sensitivity and large stretchability are desirable for strain sensors in wearable applications. However, these two performance indicators are contradictory, since the former requires a ...conspicuous structural change under a tiny strain, whereas the latter demands morphological integrity upon a large deformation. Developing strain sensors with both a high sensitivity (gauge factor (GF) > 100) and a broad strain range (>50%) is a considerable challenge. Herein, a unique Ti3C2Tx MXene nanoparticle–nanosheet hybrid network is constructed. The migration of nanoparticles leads to a large resistance variation while the wrapping of nanosheet bridges the detached nanoparticles to maintain the connectivity of the conductive pathways in a large strain region. The synergetic motion of nanoparticles and nanosheets endows the hybrid network with splendid electrical–mechanical performance, which is reflected in its high sensitivity (GF > 178.4) over the entire broad range (53%), the super low detection limit (0.025%), and a good cycling durability (over 5000 cycles). Such high performance endows the strain sensor with the capability for full‐range human motion detection.
A strain sensor based on a Ti3C2Tx nanoparticle‐nanosheet hybrid network exhibits high sensitivity over the entire broad range due to the synergetic motion of nanoparticles and nanosheets and a constrained microcrack propagation mechanism. The migration of nanoparticles leads to a large resistance variation while the wrapping of the nanosheets bridges the nanoparticles and maintains the connectivity of the conductive pathways.
Abstract
A high sensitivity and large stretchability are desirable for strain sensors in wearable applications. However, these two performance indicators are contradictory, since the former requires ...a conspicuous structural change under a tiny strain, whereas the latter demands morphological integrity upon a large deformation. Developing strain sensors with both a high sensitivity (gauge factor (GF) > 100) and a broad strain range (>50%) is a considerable challenge. Herein, a unique Ti
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MXene nanoparticle–nanosheet hybrid network is constructed. The migration of nanoparticles leads to a large resistance variation while the wrapping of nanosheet bridges the detached nanoparticles to maintain the connectivity of the conductive pathways in a large strain region. The synergetic motion of nanoparticles and nanosheets endows the hybrid network with splendid electrical–mechanical performance, which is reflected in its high sensitivity (GF > 178.4) over the entire broad range (53%), the super low detection limit (0.025%), and a good cycling durability (over 5000 cycles). Such high performance endows the strain sensor with the capability for full‐range human motion detection.
As an important subfield of flexible electronics, conductive fibers have been an active area of research. The interfacial interaction between nanostructured conductive materials with elastic ...substrates plays a vital role in the electromechanical performance of conductive fibers. However, the underlying mechanism has seldom been investigated. Here, we propose a fabricating strategy for a silver nanowire (Ag NW)/polyurethane composite fiber with a sheath-core architecture. The interfacial bonding layer is regulated, and its influence on the performance of conductive fibers is investigated, based on which an interfacial interaction model is proposed. The model underlines the significance of the embedding depth of the Ag NW network. Both supersensitive (gauge factor up to 9557) and ultrastable (negligible conductance degradation below the strain of 150%) conductive fibers are obtained via interface regulating, exhibiting great potential in the applications of wearable sensors and stretchable conducting connections.
The increased prevalence of chronic disease in aging population entails health risks and imposes significant economic and social burden. It is essential to provide comfortable, cost-effective, and ...easy-to-use unobtrusive and wearable systems for personal well-being and healthcare. Novel flexible material-based non-invasive and wearable sensors offer an efficient and cost-effective solution, which enables the continuous and real-time monitoring of important physiological signs of the human beings, the assessment of personal health conditions and that provides feedback from remote and home monitoring. In this paper, novel flexible material-based wearable sensors, devised into body sensor networks to capture and monitor vital bio-signals, including electroencephalography (EEG), electrocardiography (ECG) and respiratory, are proposed. Silver nanowires (Ag NWs) and polydimethylsiloxane composite material, carbon foam, and graphene-based fiber are used to sense the EEG, ECG, and respiratory, respectively. With different flexible materials, the smart hat and smart jacket are designed to affix the sensors, which enable long-term health monitoring of vital signals seamlessly. Meanwhile, the corresponding acquisition circuits are developed and mounted with the proposed electrodes on the garments. More importantly, a comprehensive protocol is designed to validate the performance of the proposed system, while some standard sensors and commercial devices are used for comparison. The evaluation results demonstrate the proposed system represents a comparable performance with the existing system. In summary, the proposed sensing system offers an unobtrusive, detachable, expandable, user-friendly, and comfortable solution for physiological signal monitoring. It can be expected to use for the remote healthcare monitoring and provide personalized information of health, fitness, and diseases.
Software systems are often released without formal specifications. To deal with the problem of lack of and outdated specifications, rule-based specification mining approaches have been proposed. ...These approaches analyze execution traces of a system to infer the rules that characterize the protocols, typically of a library, that its clients must obey. Rule-based specification mining approaches work by exploring the search space of all possible rules and use interestingness measures to differentiate specifications from false positives. Previous rule-based specification mining approaches often rely on one or two interestingness measures, while the potential benefit of combining multiple available interestingness measures is not yet investigated. In this work, we propose a learning to rank based approach that automatically learns a good combination of 38 interestingness measures. Our experiments show that the learning to rank based approach outperforms the best performing approach leveraging single interestingness measure by up to 66%.
EM (Electro Migration) performance is a key item to evaluate the reliability of the integrated circuit production. Nevertheless, with the scaling down of size and more complicated process, ...reliability has to face various serious challenges. In this work, we adjusted the top metal etching profile in the 28HKMG process and improved the EM performance effectively.
TSV (through-silicon via) technology plays a vital role in the application of stacking CIS. Nevertheless, TSV leakage and breakdown bring challenges in the performance improvement and scale ...production. The potential contributing factors to the TSV leakage are discussed and analyzed in this study. It was found that the most contributing factor is TSV profile and uniformity. Therefore, we developed a simple method as CIP process and reduced the yield loss.
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•Fundamental knowledge on SSPFR are detailed illustrated.•Catalytic mechanism of each step and development of SSPFR are reviewed.•Various strategies aimed at improving the reaction ...rate are discussed and summarized.•Applications are introduced.•Prospects for the future development of SSPFR are presented.
Fenton reaction has gained tremendous attention in the field of non-selective pollutant degradation, as •OH with powerful oxidizing capacity can be produced via H2O2 activation. However, the widespread application is limited by the continuous consumption of commercial H2O2 with high price. As an alternative strategy, self-sufficient photo-Fenton reaction (SSPFR) has been explored, where oxidant H2O2 was in-situ produced inside the system for subsequent Fenton reactions, rather than external addition. Benefiting from the low cost, high H2O2 utilization efficiency, and low risk in H2O2 storage and transportation, SSPFR became a hotpot in scientific research, and developed rapidly in recent years. Herein, we critically reviewed the state-of-the-art development of SSPFR, in which the fundamental mechanism and catalytic process were firstly introduced. Then, SSPFR reaction was divided into three cascade steps: in-situ H2O2 production, H2O2 activation, and reactive oxygen species utilization. This paper reviewed the research progress in every step, and proposes corresponding potential strategies to accelerate the reaction rate. Finally, conclusions and prospects of SSPFR for the removal of organic pollutants were proposed. This study provides a valuable resource for researchers to construct novel and efficient SSPFR systems.
Background Polygonatum cyrtonema, one of origins of Polygonata Rhizoma (HuangJing in Chinese), is traditionally steamed repeatedly before being used as herbal medicine in China. However, there has no ...standard for steaming of HuangJing. Therefore, a comprehensive study for effects of steam on polysaccharides from Polygonatum cyrtonema based on saccharide mapping, a powerful method developed for polysaccharides analysis, and pharmacological activity are still necessary, which is helpful to explore the effect of steam on the physiochemical and biological activities of its polysaccharides and develop steaming standard of Polygonatum cyrtonema. Methods To explore the effect of steam on physiochemical and biological activities of P. cyrtonema polysaccharides (PCP), six polysaccharides named PCP0, PCP1, PCP2, PCP3, PCP4 and PCP5 were extracted from the herb consecutively steamed for 0-5 times, respectively. Their molecular weight distribution, monosaccharide composition and PACE fingerprints were investigated through HPSEC-MALLS-RID, HPAEC-PAD and saccharide mapping based on polysaccharides analysis by using carbohydrate gel electrophoresis (PACE) and HPTLC, respectively. In addition, their antioxidant ability and immunostimulatory activities on RAW 264.7 cells in terms of NO production and phagocytosis were compared. Results Results suggested that molecular weights could be changed during steam, which increased by first steaming and then decreased with further steaming though all polysaccharides' molecular weights were 10.sup.5-10.sup.7 Da. They all showed irregularly spherical conformation in aqueous solution based on AFM imaging. Their monosaccharide composition and PACE fingerprints were significantly different after steaming, i.e., galactose increased while glucose and mannose decreased, and beta-1,4-Galp appeared while beta-1,4-Manp increased, after steaming. Steamed PCP significantly increased scavenging activity against ABTS radicals, while PCP0 had the best immunostimulatory effect on RAW 264.7 in terms of NO production and phagocytosis. Conclusions In summary, steam significantly affected the chemical composition and bioactivities of polysaccharides from P. cyrtonema. Considering the balance beneficial effects of steaming on antioxidant and immunopotentiation activities of PCP, 2 times of continuous steam is the optimal choice under the given conditions. Keywords: Polygonatum cyrtonema, Polysaccharides, Steam, Chemical composition, Bioactivity, Saccharide mapping
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