Osteosarcoma is one of the most common primary malignant bone tumors, mainly occurring in children and adolescents, and is characterized by high morbidity and poor prognosis. MicroRNAs, a class of noncoding RNAs consisting of 19 to 25 nucleotides, are involved in cell proliferation, invasion, metastasis, and apoptosis to regulate the development and progression of osteosarcoma. Studies have found that microRNAs are closely related to the diagnosis, treatment, and prognosis of osteosarcoma patients and have an important role in improving drug resistance in osteosarcoma. This paper reviews the role of microRNAs in the pathogenesis of osteosarcoma and their clinical value, aiming to provide a new research direction for diagnosing and treating osteosarcoma and achieving a better prognosis.

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In this study, we investigated the magnetic levitation characteristics of a high-temperature superconducting (HTS) bulk with both permanent magnet guideway (PMG) and electromagnet guideway (EMG). Trying to have the magnetic fields of the two kinds of guideways with a similar structure, then the central magnetic flux density B z and unit magnetomotive F u were selected as the evaluation indexes respectively for the comparative study. Different magnetic field characteristics on magnetic levitation performance were studied, such as the gradient of magnetic flux density and magnetic flux density component in different directions. Several experiments were carried out at different magnetic field conditions by changing the exciting current of EMG or replacing different PMG specimens. The experiments were conducted with a high-precision force-measuring platform. The experimental results show that the EMG has several different characteristics as compared with PMG. As a result, the magnetic levitation performance is related to the gradient of magnetic flux density as well as the directional magnetic flux density components. The structure of the magnetic field also has great influence on the performance. The results will be helpful for further study of the properties of HTS maglev and provide guidance for the subsequent EMG design.

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