Study on theory and operation of guided-exploring teaching mode

【摘要】导学探索式教学模式主旨是弘扬学生的主体学习精神，促使学生学会学习。导学探索式教学具有丰富的素质教育思想内涵，教学突出了学、思、导三个基本特征，教学活动体现了以教师为主导、以学生为主体、以培养学生创新精神和实践能力为主旨的“三为主”的教学思想。导学探索教学模式操作基本特点是先学后讲、先探索后讨论交流，教学活动程序大体分为导标、导学、讨论交流、教师精讲、巩固练习、评价小结等六步教学环节。Aiming at intensifying independent learning by the students and leading them to the right studying approach, the Guided-Exploring Teaching Mode emphasizes learning, thinking and guiding, which at the same time are basic features of Quality Education. Directed by the principle of teacher’s guidance, students orientation and improvement of learners’ creativity and practice, the teaching activities agree well with the methodology of inspiring teaching. The basic process of the Guided-Exploring Teaching Mode is studying prior to lecturing and exploration prior to discussion with six specific steps starting from lesson targets, lesson plan, pre-discussions, key points explaining, post-practice, to comments and summary

Multiple Unpinned Dirac Points in Group-Va Single-layers with Phosphorene Structure

Emergent Dirac fermion states underlie many intriguing properties of graphene, and the search for them constitute one strong motivation to explore two-dimensional (2D) allotropes of other elements. Phosphorene, the ultrathin layers of black phosphorous, has been a subject of intense investigations recently, and it was found that other group-Va elements could also form 2D layers with similar puckered lattice structure. Here, by a close examination of their electronic band structure evolution, we discover two types of Dirac fermion states emerging in the low-energy spectrum. One pair of (type-I) Dirac points is sitting on high-symmetry lines, while two pairs of (type-II) Dirac points are located at generic $k$-points, with different anisotropic dispersions determined by the reduced symmetries at their locations. Such fully-unpinned (type-II) 2D Dirac points are discovered for the first time. In the absence of spin-orbit coupling, we find that each Dirac node is protected by the sublattice symmetry from gap opening, which is in turn ensured by any one of three point group symmetries. The spin-orbit coupling generally gaps the Dirac nodes, and for the type-I case, this drives the system into a quantum spin Hall insulator phase. We suggest possible ways to realize the unpinned Dirac points in strained phosphorene.Comment: 30 pages, 6 figure

A Rapid, Non-invasive Method for Anatomical Observations of Tadpole Vertebrae in Vivo

The tadpole is a critical stage in the amphibian life cycle and plays an important role during the transition from the aquatic to the terrestrial stage. However, there is a large gap in tadpole research, which represents a vital component of our understanding of the diversity and complexity of the life history traits of amphibians, especially their developmental biology. Some aspects of this gap are due to limited research approaches. To date, X-ray microcomputed tomography (micro-CT) has been widely used to conduct osteology research in adult amphibians and reptiles, but little is known about whether this tool can be applied in tadpole studies. Thus, we compared the results of two methods (the bone-cartilage double-staining technique and micro-CT) to study vertebrae in tadpole specimens. The results revealed no significant difference between the two methods in determining the number of vertebrae, and micro-CT represents a rapid, non-invasive, reliable method of studying tadpole vertebrae. When scanning tadpoles, voltage is the most critical of the scanning parameters (voltage, current and scan time), and moderate scanning parameters are recommended. In addition, micro-CT performed better using specimens stored in 70% ethanol than those preserved in 10% formalin. Finally, we suggest that micro-CT should be more widely applied in herpetological research to increase specimen utilization