Carbon-based functional nanomaterials have attracted remarkable attention from the scientific community for their unique combinations of advantageous chemical and physical properties, such as superb ...electrical conductivity, excellent heat conductivity, chemical stability, advanced optical properties, and high mechanical strength. Our research group has been very actively involved in the study and further development of carbon-based functional nanomaterials and their potential applications for many years. In this feature article, we introduce our recent endeavors in the development of carbon-based nanomaterials with superior functionalities for potential application in diverse fields including solar thermal fuels, advanced thermal management, and electrochemical energy storage. The key design concepts of these advanced functional nanomaterials are highlighted, specific synthesis strategies are discussed, their potential usage in devices and applications is emphasized, and background information is succinctly furnished wherever warranted. We begin with an overview on the chemistry of carbon nanomaterials, in which the synthesis and chemical functionalization of carbon nanotubes and graphene are introduced, respectively. We then showcase the design, fabrication and properties of different functional carbon nanomaterials for diverse applications, including photoactive azobenzene/carbon nanomaterials for solar thermal fuels and light-driven carbon-based actuators, advanced carbon nanomaterials with directional thermal conductivity, and carbon-based electrodes for electrochemical energy storage. Finally, we conclude by briefly summarizing the advantages of the application of functional carbon-based nanomaterials in various fields, and list challenges that remain to be solved and potential that remains to be tapped.
The COVID-19 pandemic has caused major disruptions to every sector, including education. Virtual space during the pandemic has enabled a range of creative events, such as streaming performances, ...cyber tours, and online activities. Within confined spaces, performing artists have quickly become digital experts in pushing boundaries. This paper examines how tertiary dance teachers and students have coped with the sudden change caused by the COVID-19 pandemic. A total of 120+ university/college dance teachers and students from different continents participated in this study. The study finds that some technologies work better than others, virtual platforms are congruent with current students' learning preferences, and restrictions in space boost creativity and empathy. This paper shares timely lessons and insights on tools, pedagogies, and strategies for online teaching and learning. It aims to foster further discussions and interrogations of how far we can push practice-based subjects in education by creatively engaging digital technology.
This paper proposes a new distance-based distributionally robust unit commitment (DB-DRUC) model via Kullback-Leibler (KL) divergence, considering volatile wind power generation. The objective ...function of the DB-DRUC model is to minimize the expected cost under the worst case wind distributions restricted in an ambiguity set. The ambiguity set is a family of distributions within a fixed distance from a nominal distribution. The distance between two distributions is measured by KL divergence. The DB-DRUC model is a "min-max-min" programming model; thus, it is intractable to solve. Applying reformulation methods and stochastic programming technologies, we reformulate this "min-max-min" DB-DRUC model into a one-level model, referred to as the reformulated DB-DRUC (RDB-DRUC) model. Using the generalized Benders decomposition, we then propose a two-level decomposition method and an iterative algorithm to address the RDB-DRUC model. The iterative algorithm for the RDB-DRUC model guarantees global convergence within finite iterations. Case studies are carried out to demonstrate the effectiveness, global optimality, and finite convergence of a proposed solution strategy.
Nanostructuring is a transformative way to improve the structure stability of high capacity silicon for lithium batteries. Yet, the interface instability issue remains and even propagates in the ...existing nanostructured silicon building blocks. Here we demonstrate an intrinsically dual stabilized silicon building block, namely silicene flowers, to simultaneously address the structure and interface stability issues. These original Si building blocks as lithium battery anodes exhibit extraordinary combined performance including high gravimetric capacity (2000 mAh g–1 at 800 mA g–1), high volumetric capacity (1799 mAh cm–3), remarkable rate capability (950 mAh g–1 at 8 A g–1), and excellent cycling stability (1100 mA h g–1 at 2000 mA g–1 over 600 cycles). Paired with a conventional cathode, the fabricated full cells deliver extraordinarily high specific energy and energy density (543 Wh kgca –1 and 1257 Wh Lca –1, respectively) based on the cathode and anode, which are 152% and 239% of their commercial counterparts using graphite anodes. Coupled with a simple, cost-effective, scalable synthesis approach, this silicon building block offers a horizon for the development of high-performance batteries.
•The hot-dry environment of different temperatures was simulated in a laboratory.•The influence of surrounding rock temperature on concrete property of was analyzed.•The correlation analysis between ...temperature and pore structure was carried out.
In view of the temperature distribution of the high-temperature geothermal tunnels, the surrounding rock temperature was divided into four grades (40 °C, 60 °C, 80 °C and 100 °C) to simulate the hot-dry environment. Using the standard curing environment as a reference condition, the mechanical properties and pore structure characteristics of concrete for shotcrete use under hot-dry environments at different temperatures were studied by mechanical and mercury intrusion porosimetry (MIP) tests. Fractal dimension of pore structure was calculated through the fractal model based on thermodynamic method. Bivariate correlation analysis was conducted on the curing temperature and the pore structure parameters. The results show that the 40 °C hot-dry environment is conducive to enhance the mechanical properties of concrete and optimize its pore structure at the age of 1d. However, the hot-dry environments after 7 days will deteriorate the mechanical properties and pore structure of concrete, and the higher the temperature, the more obvious the deterioration. There is a significant correlation between curing temperature and porosity of capillary pores, median pore diameter, average pore diameter and fractal dimension.
This qualitative study investigates how two dance teachers (one in Toronto and the other in Hong Kong) shifted issues of pedagogy and autonomy in virtual dance classes during the COVID-19 pandemic. ...It reveals that participants quickly adapt to new environments and utilize available technologies in both teaching and learning. The study shares insights and practical strategies for dance educators to adapt and apply in regular dance classes even after the pandemic. In addition to teachers' perspectives on virtual teaching, selected student works highlight how the shift of autonomy fosters creativity and boosts confidence.
Tin (Sn)-based and mixed tin–lead (Sn–Pb) perovskites have attracted increased attention as promising candidates for new generation lead-free perovskite and all-perovskite tandem solar cells. ...However, as an inevitably critical issue, Sn(II) induced serious defects and oxidation and caused poor photovoltaic performance and unsatisfactory stability for Sn-based and mixed Sn–Pb perovskites. Herein, a comprehensive understanding on defect classification, defect formation, defect effect on performance, and defect passivation strategies is reviewed on the Sn(II) induced defects. The Sn(II)-based defects can be classified from the aspects of defect dimensions and shallow/deep levels in energy structure according to three main origins, i.e. low defect tolerance, oxidation, and fast crystallization. Then, the state-of-the-art defect passivation strategies including surface Lewis acid/base coordination, low/mixed dimensional perovskite design, composition regulation and crystal orientation modulation, and reducing agent assistance are summarized systematically. Lastly, several key scientific issues and future research prospectives are proposed for achieving stable and high-performance Sn-related perovskite photovoltaics.
Incorporating mixed ion is a frequently used strategy to stabilize black-phase formamidinum lead iodide perovskite for high-efficiency solar cells. However, these devices commonly suffer from ...photoinduced phase segregation and humidity instability. Herein, we find that the underlying reason is that the mixed halide perovskites generally fail to grow into homogenous and high-crystalline film, due to the multiple pathways of crystal nucleation originating from various intermediate phases in the film-forming process. Therefore, we design a multifunctional fluorinated additive, which restrains the complicated intermediate phases and promotes orientated crystallization of α-phase of perovskite. Furthermore, the additives in-situ polymerize during the perovskite film formation and form a hydrogen-bonded network to stabilize α-phase. Remarkably, the polymerized additives endow a strongly hydrophobic effect to the bare perovskite film against liquid water for 5 min. The unencapsulated devices achieve 24.10% efficiency and maintain >95% of the initial efficiency for 1000 h under continuous sunlight soaking and for 2000 h at air ambient of ~50% humid, respectively.
While the COVID-19 pandemic has been raging across the continents, performing arts educators have unlearned and adjusted their pedagogies in course delivery to surmount the challenges caused by the ...COVID-19 pandemic. Subject to the COVID-19 pandemic situation easing in Hong Kong and around the world, the whole education sector seems to be bouncing back to normal gradually. Meanwhile, there are effective lessons and insights to be learned from the hybrid pedagogy during the pandemic, which could further benefit the new normal period (post-pandemic) of performing arts education. To examine the current practice of digital learning among students and faculty (attitudes towards hybrid, online, and face-to-face learning and preferences about learning mode for professional development/training workshops), this empirical study looks at 408 students and 17 faculty members at a leading performing arts institute in Hong Kong. This study locates the key issues for performing arts educators regarding online/hybrid teaching and learning. It presents lessons and insights for quality insurance and improvement. Findings can inform the future development of digital teaching and learning for the performing arts as well as for other practice-based subjects.
