In order to make full utilization of the high intrinsic surface area of graphene, recently, porous graphene materials including graphene nanomesh, crumpled graphene and graphene foam, have attracted ...tremendous attention and research interest, owing to their exceptional porous structure (high surface area, and high pore volume) in combination with the inherent properties of graphene, such as high electronic conductivity, good thermal stability, and excellent mechanical strength. Interestingly, porous graphene materials and their derivatives have been explored in a wide range of applications in the fields of electronic and photonic devices, energy storage, gas separation/storage, oil absorption and sensors. This article reviews recent progress in the synthesis, characterization, properties, and applications of porous graphene materials. We aim to highlight the importance of designing different porous structures of graphene to meet future challenges, and the trend on future design of porous graphene materials is analyzed.
Porous graphene materials including graphene nanomesh, crumpled graphene and graphene foam, have attracted tremendous attention and research interest due to their exceptional porous structure combining with inherent properties of graphene.
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•The methods of introducing and characterizing oxygen-containing functional groups are summarized.•The influence mechanism of oxygen-containing functional groups on the performances ...of carbon materials is analyzed.•Accurately control the type and content of oxygen-containing functional groups.•Explore the equilibrium relationship between oxygen content, and conductivity in carbon materials.
Carbon materials play an indispensable role in supercapacitor devices. However, carbon materials based on the electric double-layer energy storage mechanisms limit the energy density improvement of supercapacitors. The introduction of additional redox pseudocapacitance through oxygen-containing functional groups is a novel strategy to improve the specific capacity of carbon materials. Whereas the influence mechanism of oxygen-containing functional groups on carbon-based electrode materials needs to be explored in-depth. Here, we summarize the types, introductions and characterization methods of oxygen-containing functional groups in carbon materials, and emphatically explain the effect of oxygen-containing functional groups on the structure and physico-chemical properties of carbon-based electrode materials for supercapacitors at the mechanism level, which has not been reported in previous reviews. Different types or content differences of oxygen-containing functional groups can cause changes in the polarity, surface energy, adsorption energy, impedance, energy bands and other aspects of carbon materials, and even lead to defects affecting the structure and physicochemical properties. The mutual constraint relationship between high specific capacity and excellent conductivity caused by the content of oxygen-containing functional groups is also pointed out. Carbon materials with rich oxygen are expected to be developed in lithium/sodium-ion batteries, fuel cells, electrocatalysis, sensor devices, biomedicine and other fields.
With the rapid progress of the semantic web, a huge amount of structured data has become available on the web in the form of knowledge bases (KBs). Making these data accessible and useful for ...end-users is one of the main objectives of chatbots over linked data. Building a chatbot over linked data raises different challenges, including user queries understanding, multiple knowledge base support, and multilingual aspect. To address these challenges, we first design and develop an architecture to provide an interactive user interface. Secondly, we propose a machine learning approach based on intent classification and natural language understanding to understand user intents and generate SPARQL queries. We especially process a new social network dataset (i.e., myPersonality) and add it to the existing knowledge bases to extend the chatbot capabilities by understanding analytical queries. The system can be extended with a new domain on-demand, flexible, multiple knowledge base, multilingual, and allows intuitive creation and execution of different tasks for an extensive range of topics. Furthermore, evaluation and application cases in the chatbot are provided to show how it facilitates interactive semantic data towards different real application scenarios and showcase the proposed approach for a knowledge graph and data-driven chatbot.
Aim and objective
To explore nurses’ experiences regarding shift patterns while providing front‐line care for COVID‐19 patients in isolation wards of hospitals in Shanghai and Wuhan during the novel ...coronavirus pandemic. Our findings will help to optimise shift work scheduling, use the existing nursing workforce more efficiently and improve nursing quality.
Background
Nurses are one of the main professionals fighting against COVID‐19. Providing care for COVID‐19 patients is challenging. In isolation wards, the workload has increased, and the workflow and shift patterns are completely different from the usual. More importantly, there is a shortage of nurses. Therefore, it is essential and urgent to arrange nurses’ shifts correctly and use the existing workforce resources efficiently.
Design
A qualitative descriptive study of 14 nurses in Chinese hospitals was conducted.
Methods
Semi‐structured interviews were used based on the phenomenological research method; data were analysed using Colaizzi's method of data analysis. This study aligns with the COREQ checklist.
Results
Four themes were extracted: assess the competency of nurses to assign nursing work scientifically and reasonably, reorganise nursing workflow to optimise shift patterns, communicate between managers and front‐line nurses to humanise shift patterns, and nurses’ various feelings and views on shift patterns.
Conclusion
It is necessary to arrange shift patterns scientifically and allocate workforce rationally to optimise nursing workforce allocation, reduce nurses’ workload, improve nursing quality and promote physical and mental health among nurses during the COVID‐19 pandemic.
Relevance to clinical practice
This study emphasised nurses’ experiences on shift patterns in isolation wards, providing useful information to manage shift patterns. Nursing managers should arrange shifts scientifically, allocate nursing workforce rationally, formulate emergency plans and establish emergency response rosters during the COVID‐19 pandemic.
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Herein, carbon aerogels (CA) were prepared by a facile and eco-friendly approach from glucose, an abundant and inexpensive sugar molecule, and further activated by potassium ...hydroxide. An interconnected coral-like microstructure of carbon was built up in sol–gel process, and activation process resulted in a more efficient development of microporosity and mesoporosity. Thus, activated carbon aerogels (ACA) with specific surface area up to 2413 m2·g−1 were obtained. The unique morphology, ultrahigh specific surface area, and increased functional groups rendered the obtained ACA superior adsorption capacity (194.07–1030.05 mg·g−1) for several kinds of organic pollutants, such as phenols (phenol, p-nitrophenol and resorcinol), antibiotics (tetracycline, oxytetracycline, doxycycline and sulfamethazine), and dyes (methylene blue). Among them, the adsorption of p-nitrophenol onto ACA could reach 613.34 mg·g−1 (293 K) and had a broad pH application range from 2 to 10 with good regeneration ability. The adsorption kinetics studies implied that intraparticle diffusion and pore diffusion were the limiting steps of the adsorption rate. Adsorption isotherms showed that the interaction between p-nitrophenol and ACA surface was monolayer adsorption.
We demonstrated the fabrication of functionalized graphene nanosheets via low temperature (300 °C) treatment of graphite oxide with a slow heating rate using Mg(OH)2 nanosheets as template. Because ...of its dented sheet with high surface area, a certain amount of oxygen-containing groups, and low pore volume, the as-obtained graphene delivers both ultrahigh specific gravimetric and volumetric capacitances of 456 F g–1 and 470 F cm–3, almost 3.7 times and 3.3 times higher than hydrazine reduced graphene, respectively. Especially, the obtained volumetric capacitance is the highest value so far reported for carbon materials in aqueous electrolytes. More importantly, the assembled supercapacitor exhibits an ultrahigh volumetric energy density of 27.2 Wh L–1, which is among the highest values for carbon materials in aqueous electrolytes, as well as excellent cycling stability with 134% of its initial capacitance after 10 000 cycles. Therefore, the present work holds a great promise for future design and large-scale production of high performance graphene electrodes for portable energy storage devices.
The Mott insulator is a central concept in strongly correlated physics and manifests when the repulsive Coulomb interaction between electrons dominates over their kinetic energy1,2. Doping additional ...carriers into a Mott insulator can give rise to other correlated phenomena such as unusual magnetism and even high-temperature superconductivity2,3. A tunable Mott insulator, where the competition between the Coulomb interaction and the kinetic energy can be varied in situ, can provide an invaluable model system for the study of Mott physics. Here we report the possible realization of such a tunable Mott insulator in a trilayer graphene heterostructure with a moiré superlattice. The combination of the cubic energy dispersion in ABC-stacked trilayer graphene4–8 and the narrow electronic minibands induced by the moiré potential9–15 leads to the observation of insulating states at the predicted band fillings for the Mott insulator. Moreover, the insulating states in the heterostructure can be tuned: the bandgap can be modulated by a vertical electrical field, and at the same time the electron doping can be modified by a gate to fill the band from one insulating state to another. This opens up exciting opportunities to explore strongly correlated phenomena in two-dimensional moiré superlattice heterostructures.Report of the likely observation of a Mott insulator in trilayer graphene with a moiré potential. The Mott state can be tuned between different filling fractions via gating, which will enable the careful study of this paradigmatic many-body state.
Adhesive hydrogels have gained popularity in biomedical applications, however, traditional adhesive hydrogels often exhibit short-term adhesiveness, poor mechanical properties and lack of ...antibacterial ability. Here, a plant-inspired adhesive hydrogel has been developed based on Ag-Lignin nanoparticles (NPs)triggered dynamic redox catechol chemistry. Ag-Lignin NPs construct the dynamic catechol redox system, which creates long-lasting reductive-oxidative environment inner hydrogel networks. This redox system, generating catechol groups continuously, endows the hydrogel with long-term and repeatable adhesiveness. Furthermore, Ag-Lignin NPs generate free radicals and trigger self-gelation of the hydrogel under ambient environment. This hydrogel presents high toughness for the existence of covalent and non-covalent interaction in the hydrogel networks. The hydrogel also possesses good cell affinity and high antibacterial activity due to the catechol groups and bactericidal ability of Ag-Lignin NPs. This study proposes a strategy to design tough and adhesive hydrogels based on dynamic plant catechol chemistry.
Bacterial cellulose (BC) is used as both template and precursor for the synthesis of nitrogen‐doped carbon networks through the carbonization of polyaniline (PANI) coated BC. The as‐obtained carbon ...networks can act not only as support for obtaining high capacitance electrode materials such as activated carbon (AC) and carbon/MnO2 hybrid material, but also as conductive networks to integrate active electrode materials. As a result, the as‐assembled AC//carbon‐MnO2 asymmetric supercapacitor exhibits a considerably high energy density of 63 Wh kg−1 in 1.0 m Na2SO4 aqueous solution, higher than most reported AC//MnO2 asymmetric supercapacitors. More importantly, this asymmetric supercapacitor also exhibits an excellent cycling performance with 92% specific capacitance retention after 5000 cycles. Those results offer a low‐cost, eco‐friendly design of electrode materials for high‐performance supercapacitors.
An asymmetric supercapacitor based on nitrogen‐doped porous carbon networks and 3D flower‐like MnO2 as the negative and positive electrode materials, respectively, exhibits a considerably high energy density of 63 Wh kg−1 and an excellent cycling performance with 92% specific capacitance retention after 5000 cycles. Those results offer a low‐cost, eco‐friendly design of electrode materials for high‐performance supercapacitors.
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