Objective: FNA is a simple, safe, cost-effective and accurate diagnostic tool for the initial screening of patients with thyroid nodules. The aims of this study were to determine the diagnostic utility of FNAC performed in our institution, assess the cytomorphologic features that contribute to diagnostic errors and propose improvement measures.Methods: A total of 2781 FNACs were included in the study, and 1122 cases were compared with their histological diagnoses. We retrospectively reexamined our discordant (both false-negative and false-positive) cases and performed a systematic review of previous studies on causes of misdiagnoses.Results: When DC V and DC VI were both considered cytologic-positive, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy were 98.3, 30.9, 94.9, 58.3 and 93.5%, respectively. If DC VI was considered cytologic-positive, the sensitivity, specificity, PPV, NPV and diagnostic accuracy of FNAC were 98.0, 84.0, 99.4, 58.3, and 97.5% respectively. The main cause of false-negative diagnoses was sampling error (13/15, 86.7%), while interpretation error led to the majority of the false-positive diagnoses (38/47, 80.9%). Overlapping cytological features in adenomatous hyperplasia, thyroiditis and cystic lesions were the major factors contributing to interpretation errors, while the size and number of nodules may have led to false-negative diagnoses because of heterogeneity and unsampled areas.Conclusions: The sensitivity and PPV of thyroid FNAC in our institution were higher than those in the published data, while the specificity and NPV were lower. Regarding the FNA category DC V, a frozen section analysis during diagnostic lobectomy is necessary. Multiple passes should be performed in various parts of a large nodule or from different nodules to reduce the risk of false-negative findings. Cytopathologists should strengthen their criteria for the identification of adenomatous hyperplasia, thyroiditis and cystic lesions to avoid false-positive diagnoses. NIFTP has little effect on diagnostic accuracy and the distribution of diagnostic errors.

Mastering nuclear fusion, which is an abundant, safe, and environmentally competitive energy, is a great challenge for humanity. Tokamak represents one of the most promising paths toward controlled fusion. Obtaining a high-performance, steady-state, and long-pulse plasma regime remains a critical issue. Recently, a big breakthrough in steady-state operation was made on the Experimental Advanced Superconducting Tokamak (EAST). A steady-state plasma with a world-record pulse length of 1056 s was obtained, where the density and the divertor peak heat flux were well controlled, with no core impurity accumulation, and a new high-confinement and self-organizing regime (Super I-mode = I-mode + e-ITB) was discovered and demonstrated. These achievements contribute to the integration of fusion plasma technology and physics, which is essential to operate next-step devices.

Fusion energy is a promising source of clean energy, which could solve energy shortages and environmental pollution. Research into controlled fusion energy has been ongoing for over half a century. China has created a clear roadmap for magnetic confinement fusion development, where superconducting tokamaks will be used in commercial fusion reactors. The Experimental Advanced Superconducting Tokamak (EAST) is the world’s first fully superconducting tokamak with upper and lower divertors, which aims at long-pulse, steady-state, H-mode operation, and 101-s H-mode discharge had been achieved. In 2007, China joined the International Thermonuclear Experimental Reactor (ITER) and became one of its seven members. Thirteen procurement packages are undertaken by China, covering superconducting magnets, power supplies, plasma-facing components (PFCs), diagnostics, etc. To bridge the gap between the ITER and fusion demonstration power plants (DEMOs), China is planning to build the Chinese Fusion Engineering Testing Reactor (CFETR) to demonstrate related technologies and physics models. The engineering design of the CFETR was completed in 2020, and Comprehensive Research Facilities for Fusion Technology (CRAFT) are being constructed to explore the key technologies used in the CFETR.

The concept design of CFETR (China Fusion Engineering Test Reactor) was started in 2012 in two stages. For CFETR-Phase I, the major radius is 5.7m, minor radius is 1.6m and the magnetic field at plasma region BT is 4-5T. There were 16 toroidal field coils and 6 central solenoid coils designed by Nb3Sn CICC with the maximum operation current of 64 kA and 50 kA, respectively. Three types of plasma equilibrium configuration-ITER-like, super-X and snowflake were designed. The maximum flux provided by the central solenoid is set at 180 volt second. However, to get much higher operation parameters such as steady-state operation,the superconducting magnet system of CFETR-phase II has been updated based on the larger machine with R = 6.7m, a=2.0m, BT= 6.5-7T.Hybrid TF coils are designed by high performance Nb3Sn conductor, which's maximum magnetic field can reach to 14-15 T. Besides, in order to save the space for blanket system and get higher flux, high temperature superconducting Bi-2212 magnet with better current carrying performance under high field is supposed to be employed for the CS coils of CFETR. The Bi-2212 CICC conductor sample has been tested at 4.2 K with criti-cal current of 26.6 kA under its self-field.

Quench protection is a critical issue for magnet using high temperature superconducting (HTS) materials like REBCO. For cable-in-conduit conductor (CICC) with twisted REBCO tapes, which is considered for high current HTS conductor for fusion magnet, the anisotropic critical current density (Jc) of tape and complex conductor layout will further complicate the quench behavior. The CryoSoft code THEA is used to simulate the quench behavior of various sub-scale CICCs in view of a quench experiment in SULTAN facility. The CICCs are composed of the twisted tape stack assembled into copper shell (strand). It has been found that neglecting the anisotropy of Jc in quench simulation will significantly underestimate the hot spot temperature by about 40 K. Therefore, it could leave potential risk to damage the magnet. It is also shown that the thermal contact resistance between strand and the steel jacket (the conduit) plays a very important role on quench behavior. The hot spot temperature can be reduced by more than 100 K if the thermal resistance is reduced by two order of magnitude. On the other hand, variations of inter-strand electrical and/or thermal resistance have only very little influence (few Kelvin).