A novel self‐powered UV photodetector based on electrospun ZnO nanofiber arrays is introduced. Aligned pure ZnO nanofibers and Ag‐doped p‐type ZnO nanofibers are processed perpendicular to each ...other, and p–n junction arrays of ZnO nanofibers are fabricated as a result. Owing to the intrinsic intervals between nanofibers, the device is fully transparent on quartz substrate. Various characterization methods including TEM, XRD, and XPS are used to testify the existence form of Ag element in ZnO nanofibers, and a field effect transistor is constructed to judge their conductivity. It is discovered that the Ag doping process not only transforms ZnO to p‐type conductivity, making it possible to build this self‐powered photodetector, but also forms Ag nanoparticles in ZnO nanofibers and thus helps reduce the response time. Benefiting from the abovementioned dual effects, this UV detector is found to have an enhanced performance, with the on–off ratio up to 104 at zero bias and a rather short rise/decay time of 3.90 s/4.71 s.
A novel transparent and self‐powered UV photodetector based on crossed ZnO nanofiber array homojunction is fabricated by partially Ag‐doping in electrospinning process, which exhibits high on–off ratio and fast response. The Ag‐doping not only transforms ZnO to p‐type conductivity to build p–n junction, but also forms Ag nanoparticles inside ZnO nanofibers to build internal Schottky barriers and reduce response time.
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Uniformly aligned electrospun nanofiber arrays are important building blocks for high-performance functional devices and device arrays. However, it remains a challenge to prepare perfectly aligned ...and large area nanofiber arrays using common electrospinning. In this work, a modified electrospinning method utilizing three assisted electrodes for nanofiber collection was proposed to achieve uniformly aligned and millimeter-long ZnO and NiO nanofiber arrays (more than 90% of nanofibers aligned to within ±4° of the desired direction), which were further fabricated into ZnO/NiO heterojunction arrays with a density of 10 6 cm −2 . Photodetectors (PDs) based on the as-prepared ZnO/NiO heterojunction arrays exhibited excellent ultraviolet (UV) selective and self-powered detection properties because of the properly matched energy bands of ZnO and NiO. A maximum responsivity of 0.415 mA W −1 and a short rise/decay time of 7.5 s/4.8 s at 0 V bias of the device markedly outstripped the reference ZnO nanofiber array device. The three-assisted-electrode electrospinning method of this work offers new chances in novel nanostructure design and high-performance device fabrication.
Inspired by nanoscience and nanoengineering, numerous nanostructured materials developed by multidisciplinary approaches exhibit excellent photoelectronic properties ranging from ultraviolet to ...terahertz frequencies. As a new class of building block, nanoscale elements in terms of quantum dots, nanowires, and nanolayers can be used for fabricating photodetectors with high performance. Moreover, in conjunction with traditional photodetectors, they exhibit appealing performance for practical applications including high density of integration, high sensitivity, fast response, and multifunction. Therefore, with the perspective of photodetectors constructed by diverse low‐dimensional nanostructured materials, recent advances in nanoscale photodetectors are discussed here; meanwhile, challenges and promising future directions in this research field are proposed.
Nanostructured materials with different dimensions, such as nanolayers, nanowires, and quantum dots, exhibit excellent photoelectronic properties for photodetectors ranging from the ultraviolet to terahertz frequencies. Besides excellent performances of high sensitivity and fast response for practical applications, they also exhibit many appealing features like high density of integration and multifunction, in conjunction with traditional photodetectors.
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This article investigates group decision-making (GDM) problems, where the decision makers' (DMs) preference information is represented by incomplete interval-valued intuitionistic fuzzy preference ...relations (IVIFPRs). First, a multiplicative consistency property and an acceptably multiplicative consistency property for IVIFPRs are offered. Then, an optimization model to estimate the missing values in an incomplete IVIFPR is constructed. Subsequently, two optimization models are, respectively, established to derive a perfectly consistent IVIFPR and an acceptably consistent IVIFPR from a given inconsistent IVIFPR. Furthermore, a model is offered to gain the DMs' weights. Afterward, the consensus index is defined. When the consensus for IVIFPRs is unacceptable, a model is presented to reach the consensus requirement. Moreover, a novel GDM method for incomplete IVIFPRs is presented. Finally, the presented method is applied to an illustrative example that shows the feasibility of the offered method.
The crystal structure of a material creates a periodic potential that electrons move through giving rise to its electronic band structure. When two-dimensional materials are stacked, the resulting ...moiré pattern introduces an additional periodicity so that the twist angle between the layers becomes an extra degree of freedom for the resulting heterostructure. As this angle changes, the electronic band structure is modified leading to the possibility of flat bands with localized states and enhanced electronic correlations1–6. In transition metal dichalcogenides, flat bands have been theoretically predicted to occur for long moiré wavelengths over a range of twist angles around 0° and 60° (ref. 4) giving much wider versatility than magic-angle twisted bilayer graphene. Here, we show the existence of a flat band in the electronic structure of 3° and 57.5° twisted bilayer WSe2 samples using scanning tunnelling spectroscopy. Our direct spatial mapping of wavefunctions at the flat-band energy show that the localization of the flat bands is different for 3° and 57.5°, in agreement with first-principles density functional theory calculations4.Using scanning tunnelling spectroscopy, the flat bands in twisted bilayer WSe2 are shown near both 0° and 60° twist angles.
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FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Heating accounts for a large proportion of energy consumption in residential buildings located in cold climate. Solar energy plays an important role in responding to the growing demand of energy as ...well as dealing with pressing climate change and air pollution issues. Solar energy is featured with low-density and intermittency, therefore an appropriate storage method is required. This paper reports a critical review of existing studies on thermal storage systems that employ various methods. Latent heat storage using phase change materials (PCMs) is one of the most effective methods to store thermal energy, and it can significantly reduce area for solar collector. During the application of PCM, the solid–liquid phase change can be used to store a large quantity of energy where the selection of the PCM is most critical. A numerical study is presented in this study to explore the effectiveness of NH4Al(SO4)2·12H2O as a new inorganic phase change material (PCM). Its characteristics and heat transfer patterns were studied by means of both experiment and simulation. The results show that heat absorption and storage are more efficient when temperature of heat source is 26.5°C greater than the phase transition temperature. According to heat transfer characteristics at both radial and axial directions, it is suggested to set up some small exchangers so that solar energy can be stored unit by unit in practice. Such system is more effective in low density residential buildings.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Protein structure prediction (PSP) problems are a major biocomputing challenge, owing to its scientific intrinsic that assists researchers to understand the relationship between amino acid sequences ...and protein structures, and to study the function of proteins. Although computational resources increased substantially over the last decade, a complete solution to PSP problems by computational methods has not yet been obtained. Using only one energy function is insufficient to characterize proteins because of their complexity. Diverse protein energy functions and evolutionary computation algorithms have been extensively studied to assist in the prediction of protein structures in different ways. Such algorithms are able to provide a better protein with less computational resources requirement than deep learning methods. For the first time, this study proposes a many-objective PSP (MaOPSP) problem with four types of objectives to alleviate the impact of imprecise energy functions for predicting protein structures. A many-objective evolutionary algorithm (MaOEA) is utilized to solve MaOPSP. The proposed method is compared with existing methods by examining 34 proteins. An analysis of the objectives demonstrates that our generated conformations are more reasonable than those generated by single/multiobjective optimization methods. Experimental results indicate that solving a PSP problem as an MaOPSP problem with four objectives yields better PSPs, in terms of both accuracy and efficiency. The source code of the proposed method can be found at https://toyamaailab.github.io/sourcedata.html .
While the career transition of athletes has been explored to several extents, it is often marked by complex psychosocial challenges and requires a redefined sense of identity and professional ...purpose. Research to date has predominately focused on the disadvantages or inequity emerging from broad social demographics without delving into specific career transition pathways, such as into higher education settings. This study specifically investigates the unique psychosocial factors underlying the career transition of retired Chinese athletes into higher education. We conducted an interview phase with retired Chinese athletes (Phase 1, n = 17) and a Delphi phase with senior human resources (HR) managers from Chinese higher education settings (Phase 2, n = 15). This approach allowed us to understand the lived experiences and challenges of these athletes within the Chinese cultural and social context, as well as HR experts’ perceptions of their career transitions, respectively. The results unveil crucial psychosocial factors that motivate, and the barriers that challenge, and difficulties retired Chinese athletes in their transition, informing intervention and policy efforts to facilitate their successful integration into higher education.
Design and synthesis of low-cost visible-light-active catalysts for photodegradation of organic dyes has been regarded as an efficient way for the utilization of solar energy to address the ...environmental issues. In this work, visible-light-active TiO2 photocatalyst were synthesized via a simple solvothermal method by reaction of tetrabutyl titanate and oleylamine in the presence of 1, 2-ethanedithiol. The resulting TiO2 (T-S) possesses of a broadband visible light absorption capacity, with the absorption band edge of ~574 nm. UV–vis absorption spectroscopy and Mott-Schottky curve measurements demonstrate that the band gap of T-S can be reduced to ~2.16 eV with the conduction band of −0.58 eV compared to that of typical P25 (~3.21 eV). As a result, the T-S sample exhibits efficient photocatalytic performance for removal of rhodamine B (Rh B) and methylene blue (MB). Under visible light irradiation, the photodegradation efficiency can reach to as high as >95% in 60 min for Rh B and MB (10 mg/L). A probable charge carrier transport path for this photocatalytic process, where the photo-generated e−, h+ and forming oxygen species •O2−, •OH under visible light irradiation cooperatively catalyze the molecules of Rh B and MB in solution. This work put forward a simple strategy for synthesizing visible-light-active photocatalytic materials.
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•Visible-light-active TiO2 photocatalyst has been fabricated in the presence of 1, 2-ethanedithiol.•Its bandgap value was estimated to 2.16 eV and the corresponding wavelength was extended to 574 nm.•The probable mechanism of photogenerated carriers was discussed under visible light.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Metal–organic layers (MOLs) represent an emerging class of tunable and functionalizable two‐dimensional materials. In this work, the scalable solvothermal synthesis of self‐supporting MOLs composed ...of Hf6O4(OH)4(HCO2)6 secondary building units (SBUs) and benzene‐1,3,5‐tribenzoate (BTB) bridging ligands is reported. The MOL structures were directly imaged by TEM and AFM, and doped with 4′‐(4‐benzoate)‐(2,2′,2′′‐terpyridine)‐5,5′′‐dicarboxylate (TPY) before being coordinated with iron centers to afford highly active and reusable single‐site solid catalysts for the hydrosilylation of terminal olefins. MOL‐based heterogeneous catalysts are free from the diffusional constraints placed on all known porous solid catalysts, including metal–organic frameworks. This work uncovers an entirely new strategy for designing single‐site solid catalysts and opens the door to a new class of two‐dimensional coordination materials with molecular functionalities.
A very thin catalyst: Two‐dimensional metal–organic layers with the thinness of a single monolayer act as highly efficient single‐site solid catalysts for alkene hydrosilylation. They outperform traditional metal–organic frameworks in terms of their activity as diffusional constraints on the substrates and products are removed.
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