Never in mitosis gene A (NIMA)-related kinase 2 (NEK2) is a microtubule-associated protein that regulates spindle assembly in human cells and is overexpressed in various malignancies. However, the role of NEK2 in hepatocellular carcinoma (HCC) remains undetermined. We performed RNA-seq of the HCC cell line SMMC-7721 and the normal liver cell line HL-7702 using the Ion Proton System. NEK2 expression was detected using quantitative reverse transcription polymerase chain reaction in two cell lines and 5 matched HCC and adjacent non-tumorous liver tissues. The correlation between survival and NEK2 expression was analyzed in 359 patients with HCC using RNASeqV2 data available from The Cancer Genome Atlas (TCGA) website (https://tcga-data.nci.nih.gov/tcga/). The expression of NEK2, phospho-AKT and MMP-2 was evaluated by immunohistochemistry in 63 cases of HCC and matched adjacent non-tumorous liver tissues. Relationships between protein expression and clinicopathological parameters were assessed, and the correlations between NEK2 with phospho-AKT and MMP-2 expressions were evaluated. A total of 610 differentially expressed genes (DEGs) were revealed in the transcriptome comparison, 297 of which were upregulated and 313 were downregulated in HCC. NEK2, as the most obviously different DEG in cells and tissues from the RNA-seq data, was listed as an HCC candidate biomarker for further verification. NEK2 was overexpressed in HCC cells and tissues (P=0.002, P=0.013) and HCC patients with a high expression of NEK2 had a poor prognosis (P=0.0145). Clinical analysis indicated that the overexpression of NEK2 in HCC was significantly correlated with diolame complete (P<0.001), tumor nodule number (P=0.012) and recurrence (P=0.004). NEK2 expression was positively correlated with the expression of phospho-AKT (r=0.883, P<0.01) and MMP-2 (r=0.781, P<0.01). Overexpression of NEK2 was associated with clinicopathological characteristics and poor patient outcomes, suggesting that NEK2 serves as a prognostic biomarker for HCC. Alteration of NEK2 protein levels may contribute to invasion and metastasis of HCC, which may occur through activation of AKT signaling and promotion of MMP-2 expression.

No abstract

This paper proposes a new control strategy to reduce torque ripple in a switched reluctance motor (SRM). The flux linkage in this paper is related to model predictive flux control (MPFC). In addition, the torque hysteresis remained in the system is similar to direct torque control (DTC) and direct instantaneous torque control (DITC). The candidate voltage vectors (VVs) are selected from the torque hysteresis and the cost function is designed for the flux linkage minimization to select the best VV from candidate VVs. The advantages, as well as the improvement prospects for these methods, are discussed in details. Performance for torque ripple in steady state and the robustness in the transient state are evaluated in this paper under the simulation and experimental results, and also the possibility and some advice for model predictive control (MPC) applied to an SRM are indicated. The experimental result for the new method is carried out on a three-phase 12/8 poles SRM with the analysis of torque ripple compared to a DTC and DITC. INDEX TERMSDirect torque control, model predictive control, switched reluctance motor. AIDE XU received the B.S. degree in electric traction and transmission control from Dalian Jiaotong University, Dalian, China, in 1997, and the M.S. degree in power electronics and power drives and the Ph.D. degree in marine engineering from

No abstract

In this paper, to solve the problem of large torque ripple in a switched reluctance motor (SRM), a new control strategy based on model predictive flux control is proposed in the direct torque control (DTC) algorithm. First, the flux linkage value in the next period is calculated from the discrete time model of the SRM. Second, to reduce the computation burden and increase the dynamic response, a torque hysteresis controller is embedded in the system to select three candidate voltage vectors for the cost function. Finally, based on flux linkage minimization, the best voltage vector is selected and applied to the system. The proposed direct torque and predictive flux control (DTPFC) method perfectly suits the nonlinear magnetic characteristics of SRM, and shows better steady‐state and dynamic‐state performances compared to DTC. Furthermore, since DTPFC has only one variable in the cost function, the huge task of obtaining the best weighting factor is eliminated. Simulation and experiments are carried out on a three‐phase 12/8 SRM with the proposed control algorithm and DTC. The results demonstrate the validity of the new control approach. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.