Search

Metaverse is the future of the Internet and integrates a variety of information technologies. It leads future education trends and brings profound changes to education. On the basis of analysis of the development trend of smart education and the connotation and action mechanism of edu-metaverse in the view of metaverse, this paper structures the smart education ecosystem, builds the scenario and modular smart learning space of three education scenarios of resource collaborative interaction, virtuality-reality integration experience, and ubiquitous spatial inquiry by using the six core technologies, and forms the new education mode of virtuality-reality symbiosis, trans-spatial fusion, and collaborative inquiry. Then, it verifies the application effect by AHP. Finally, it creates the smart education ecosystem of “four ecology integration”—resource ecology, interaction ecology, space ecology, and collaboration ecology, which accelerates the organic integration of metaverse and smart education and provides theoretical basis and reference for the new application of future education.

Supplementary document for the main manuscript

This study was to investigate effects of zinc oxide nanoparticle (Nano-ZnO) on growth, immunity, intestinal morphology and function of intrauterine growth retardation (IUGR) finishing pigs. Six normal birth weight (NBW) and 12 IUGR male piglets were obtained and weaned at 21 d. NBW-weaned piglets fed basal diets (NBW group), IUGR-weaned piglets allocated to two groups fed basal diets (IUGR group) and basal diets further supplemented 600 mg Zn/kg from Nano-ZnO (IUGR+Zn group), respectively. All pigs were slaughtered at 163 d. Results showed: (1) IUGR pigs showed no difference in body weight at 77d and 163d (P > 0.05), while had increased villus height (VH) and villus surface area in jejunum (P < 0.05) and enhanced interleukin-6, TNF-α and NF-κB mRNA expression (P < 0.05) as compared to NBW group; Compared with IUGR group, dietary Nano-ZnO did not affect the body weight (P > 0.05), but increased VH to crypt depth ratio and IgA concentration (P < 0.05) and decreased TNF-α and NF-κB mRNA expression in jejunum (P < 0.05). (2) IUGR increased the number of swollen mitochondria and autolysosomes, and protein expressions of sequestosome-1 (P62) and microtubule-associated protein light chain 3 B/A (LC3B/A) in jejunum as compared to NBW group (P < 0.05); Compared with IUGR group, Nano-ZnO decreased the number of swollen mitochondria and autolysosomes, and P62 and LC3B/A protein expression (P < 0.05). (3) IUGR increased mucosal contents of malondialdehyde and protein carbonyl (PC) and Keap1 protein expression (P < 0.05) as compared to NBW group; Compared with IUGR group, dietary Nano-ZnO increased activities of total antioxidant capacity, catalase, glutathione peroxidase, and glutathione content (P < 0.05), and enhanced nuclear respiratory factor 2 (Nrf2), glutamate-cysteine ligase modifier subunit and glutathione peroxidase 1 mRNA expression, and increased total and nuclear Nrf2 protein expression (P < 0.05), and decreased malondialdehyde and PC content, and Keap1 protein expression (P < 0.05) in jejunum. Results suggested that IUGR pigs showed postnatal catch-up growth and improved intestinal morphology, and dietary Nano-ZnO may further improve intestinal morphology, reduce inflammation, decrease autophagy and alleviate oxidative stress via Nrf2/Keap1 pathway in jejunum of IUGR pigs.

Topological systems are inherently robust to disorder and continuous perturbations, resulting in dissipation-free edge transport of electrons in quantum solids, or reflectionless guiding of photons and phonons in classical wave systems characterized by topological invariants. Despite considerable efforts, direct experimental demonstration of theoretically predicted robust, lossless energy transport in topological insulators operating at terahertz frequencies is needed further investigations to shed affirmative light on the unique properties enabled by topological protection. Here, we introduce Kagome lattice that exhibits a new class of symmetry-protected topological phases with very low Berry curvature but nontrivial bulk polarization, and fabricate an optical topological insulator that provide the valley hall effect. Theoretical analysis show that four type edge states can be obtained. Measurements of THz-TDs with high time-resolution demonstrate that terahertz wave propagating along the straight topological edge and Z-shape edge with sharp turns have almost same high transmission in 0.440 THz to 0.457 THz domain range. Those results quantitatively illustrate the suppression of backscattering due to the non-trivial topology of the structure. The THz-TDs measurement yields amplitude and phase information, showing significant advantage compared to general broadband infrared, single wavelength continuous-wave THz measurements and visible spectroscopy. It allows further exploration of the effective refractive index, group velocity and dispersion relations of edge states. Our work offers possibilities for advanced control of the propagation and manipulation of THz waves, and facilitates the applications including sixth-generation (6G) wireless communication, terahertz integrated circuits, and interconnects for intrachip and interchip communication.

The integration of large-scale uncontrollable renewable power greatly affects the security and reliability of power system operations. An effective way of coping with this challenge is to e...

The coordinated operations of multiple-reservoir cascaded hydropower plants provide opportunities to increase the benefits of the entire river system. However, it is very challenging to fairly allocate the incremental benefits of cooperation among all participant hydropower plants, which is critical to the implementation of operation polices in practice. A methodology that combines POA-DDDP–based multidimensional search algorithm(PDMSA) with game theory is proposed to address this challenge. The PDMSA is developed to determine optimal operation decisions and obtain the multi-yearly average revenue under all possible coalitions of plants. Thus, the cooperation benefit can be accurately calculated based on the differences of generation production revenue among various coalitions. The game-theoretic Shapley method is used to find the appropriate share of each cooperating plant from overall cooperation benefits. The cooperative core based on a set of necessary conditions helps select possibly stable allocation schemes, and their stability is evaluated by the propensity to disrupt(PTD). The proposed methodology is applied to a multiple-reservoir hydropower system on Lancang River, which is one of 14 large hydropower bases in China. This case shows that the method provides the most stable incremental allocation scheme by comparison with several commonly used methods.

Description of the models which are used in the main paper

Description of the models which are used in the main paper

Supercontinuum (SC) generation based on ultrashort pulse compression constitutes one of the most promising technologies towards an ultra-wide bandwidth, high-brightness and spatially coherent light sources for applications such as spectroscopy and microscopy. Here, multi-octave SC generation in a gas-filled hollow-core antiresonant fiber (HC-ARF) is reported spanning from 200 nm in the deep ultraviolet (DUV) to 4000 nm in the mid-infrared (mid-IR). A measured average output power of 5 mW was obtained by pumping at the center wavelength of the first anti-resonance transmission window (2460 nm) with ~100 fs pulses and an injected pulse energy of ~7-8 {\mu}J. The mechanism behind the extreme spectral broadening relies upon intense soliton-plasma nonlinear dynamics which leads to efficient soliton self-compression and phase-matched dispersive wave (DW) emission in the DUV region. The strongest DW is observed at 275 nm having an estimated pulse energy of 1.42 {\mu}J, corresponding to 28.4 % of the total output energy. Furthermore, the effect of changing the pump pulse energy and gas pressure on the nonlinear dynamics and their direct impact on SC generation was investigated. The current work paves a new way towards novel investigations of gas-based ultrafast nonlinear optics in the emerging mid-IR spectral regime.

A lot of optical components with large aperture are employed in high-power solid-state laser driver. These optical components are with high requirement on the surface shape, optical homogeneity and stress distribution. In order to test these parameters, different types of interferometers, surface profilers and stress meters from different manufacturers are needed. But the problem is the products from different manufacturers may provide different test results. To solve the problem, the research and verification of the key measurement technologies of large aperture optical components are carried out in this paper. The absolute flatness and optical homogeneity measurement methods are analyzed. And the test results of different interferometric software are compared. The test results from different surface profilers and stress meters are also compared. The consistency and reliability of different test software are obtained with the comparing results, which will guide users to select a suitable product.

Efficient supercontinuum generation (SCG) requires excitation of solitons at the pump laser wavelength. Quadratic nonlinear waveguides may support an effective self-defocusing nonlinearity so solitons can directly be generated at common ultrafast laser wavelengths without any waveguide dispersion engineering. We here experimentally demonstrate efficient SCG in a standard lithium niobate (LN) waveguide without using quasi-phase matching (QPM). By using femtosecond pumps with wavelengths in the $1.25-1.5 \mu\rm m$ range, where LN has normal dispersion and thus supports self-defocusing solitons, octave-spanning SCG is observed. An optimized mid-IR waveguide design is expected to support even broader spectra. The QPM-free design reduces production complexity, allows longer waveguides, limits undesired spectral resonances and effectively allows using nonlinear crystals where QPM is inefficient or impossible. This result is important for mid-IR SCG, where QPM-free self-defocusing waveguides in common mid-IR nonlinear crystals can support solitons directly at mid-IR ultrafast laser wavelengths, where these waveguides have normal dispersion., Comment: To appear in Optics Letters

We study the anisotropic nature of the Kerr nonlinear response in a beta-barium borate (��-BaB2O4, BBO) nonlinear crystal. The focus is on determining the relevant $��^{(3)}$ cubic tensor components that affect interaction of type I cascaded second-harmonic generation. Various experiments in the literature are analyzed and we correct the data from some of the experiments for contributions from cascading as well as for updated material parameters. We find that the Kerr nonlinear tensor component responsible for self-phase modulation in cascading is considerably larger than what has been used to date. We evaluate the impact of using such a cubic anisotropic response in ultrafast cascading experiments., Updated version, comments on experiments from the literature welcome

A diffusion model for industrial sources and a chemical element balance (CEB) method for non-industrial sources are combined to estimate the contributions of various sources to the suspended particulate matter (SPM), dust fall and total suspended particles (TSP) in Shanghai. The SPM is defined as those particles with diameters d 40 μm, to TSP are also acquired. Settlings of particles, reflection and washout by rain are considered in the diffusion model, in which the emission rates of particulate matter are associated with size distributions, depending on different types of boilers and dust collectors. The data of mass-spectrum of chemical elements associated with two size-ranges, d