RESUMEN
Single-element polarization in low dimensions is fascinating for constructing next-generation nanoelectronics with multiple functionalities, yet remains difficult to access with satisfactory performance. Here, spectroscopic evidences are presented for the spontaneous electronic polarization in tellurium (Te) films thinned down to bilayer, characterized by low-temperature scanning tunneling microscopy/spectroscopy. The unique chiral structure and centrosymmetry-breaking character in 2D Te gives rise to sizable in-plane polarization with accumulated charges, which is demonstrated by the reversed band-bending trends at opposite polarization edges in spatially resolved spectra and conductance mappings. The polarity of charges exhibits intriguing influence on imaging the moiré superlattice at the Te-graphene interface. Moreover, the plain spontaneous polarization robustly exists for various film thicknesses, and can universally preserve against different epitaxial substrates. The experimental validations of considerable electronic polarization in Te multilayers thus provide a realistic platform for promisingly facilitating reliable applications in microelectronic devices.
RESUMEN
BACKGROUND: Currently, problem-based learning (PBL) has been widely used in many disciplines, but no systematic review has explored the advantages and disadvantages of PBL in orthopaedics education. METHODS: We searched the PubMed, Cochrane Library, Embase, Web of Science, Scopus, Chongqing VIP Database (VIP), Chinese National Knowledge Infrastructure (CNKI), and Wanfang databases up to April 2023 to identify for relevant studies. Relevant studies were identified by using specific eligibility criteria, and data were extracted. RESULTS: A total of 51 randomized controlled trials with 4268 patients were included. Compared with traditional education, PBL teaching yielded significantly higher knowledge scores (SMD=1.10, 95% CI: 0.78~1.41, P<0.00001), procedural skill scores and clinical skill scores than traditional teaching (SMD=2.07, 95% CI: 1.61~2.53, P<0.00001; SMD=1.20, 95% CI: 0.88~1.52, P<0.00001). Moreover, the total scores were higher in the PBL teaching group than in the traditional teaching group (MD=5.69, 95% CI: 5.11~6.26, P<0.00001). Students also expressed higher levels of interest and satisfaction in the PBL teaching group than in the traditional teaching group (OR=4.70, 95% CI: 3.20~6.93, P<0.00001; OR=5.43, 95% CI: 3.83~7.69, P<0.00001). However, there was less learning time and higher levels of learning pressure in the PBL teaching group (OR=0.12, 95% CI: 0.06~0.24, P<0.00001; OR=5.95, 95% CI: 3.16~11.23, P<0.00001). CONCLUSION: Current evidence indicates that PBL teaching can increase knowledge scores, procedural skill scores, and clinical skill scores. Students have higher levels of interest in teaching and higher levels of teaching satisfaction in the PBL group. However, students can feel higher levels of study pressure and experience less study time. The findings of the current study need to be further verified in multicentre, double-blind and large-sample RCTs.
