异体骨结合骨髓间质干细胞移植治疗骨缺损的动物实验

【目的】研究使用异体骨混合骨髓间质干细胞移植治疗骨缺损的可行性及动物实验初步结果。【方法】将15只新西兰白兔双侧桡骨造成1 cm骨缺损模型,随机选择同一只动物的一侧为实验侧,自体配对的另一侧为对照侧。将表面脱钙的同种异体骨和来源于受体的体外培养增殖的骨髓间质干细胞混合植入实验侧骨缺损,对照侧仅植入同样制作的异体骨。12周后,进行X线检查、生物力学检查和组织学检查,将结果进行对比。【结果】动物在术后12周,实验侧X线片光密度测量结果,破坏载荷时扭矩和扭角测量结果均优于对照侧;组织学评分中,实验侧骨痂量评分优于对照侧,骨连接成熟程度和骨髓发育程度两者没有明显差异。【结论】骨髓间质干细胞可以促进异体骨在移植后的成骨作用,在增多成骨量的同时不影响骨组织发育

Enhancing students' ability and interest in geometry learning through geometric constructions

Students nowadays are relatively confident in directly applying geometrical theorems and theories. Nevertheless, it has been a common phenomenon that students are not confident in constructing geometric proofs. They lack the confidence and sufficient experience and knowledge in conducting deductive geometrical proofs. To some students, they treat proofs simply as another type of examination questions which they can tackle by repeated drillings. Students make use of straightedges and compasses to construct different geometry figures in geometric constructions. Through geometric constructions, we can train our prediction and logical thinking skills when investigating the properties of geometric figures. Geometric constructions provide students with hands-on experience to geometry learning which requires students to have more in-depth thinking. This is an empirical study on the implementation of geometric construction workshops among junior secondary students in Hong Kong. Results have shown that students enjoyed the construction tasks during the workshops. Analysis has implied that geometric constructions help improve students’ ability in constructing geometric proofs and to raise their interests in geometry learning.published_or_final_versionEducationMasterMaster of Educatio

Measurement of integrated luminosity of data collected at 3.773 GeV by BESIII from 2021 to 2024

We present a measurement of the integrated luminosity e+e- of collision data collected by the BESIII detector at the BEPCII collider at a center-of-mass energy of Ecm = 3.773 GeV. The integrated luminosities of the datasets taken from December 2021 to June 2022, from November 2022 to June 2023, and from October 2023 to February 2024 were determined to be 4.995±0.019 fb-1, 8.157±0.031 fb-1, and 4.191±0.016 fb-1, respectively, by analyzing large angle Bhabha scattering events. The uncertainties are dominated by systematic effects, and the statistical uncertainties are negligible. Our results provide essential input for future analyses and precision measurements