Effect of Percutaneous Radiofrequency Ablation and Surgical Resection on Treating of Primary Small Liver Cancer: A Meta-Analysis

Objective:To analyze the clinical effect of primary small liver cancer under radiofrequency ablation(RFA)and surgical resection(SR)treatment,and to explore the best application timing of the two treatment methods.Methods:Randomly controlled clinical trials(RCT)of percutaneous radiofrequency ablation and surgical resection for the treatment of small liver cancer in various databases were searched according to the established search strategy,and Meta data was analyzed based on RevMan5.3 software provided by Cochrane collaborative organization.Results:A total of 10 articles were included in this study,including 1396 patients,699 in the RFA group and 697 in the SR group.Meta-analysis results showed that the two groups had no statistical difference in overall survival rate at 1 and 3 years,1-year disease-free survival rate,and 1-year recurrence rate(P>0.05).The 3-year disease-free survival rate of the RFA group was lower than that of the SR group,and the 3-year recurrence rate was higher than that of the SR group.The higher postoperative complication rate tended to the SR group,and the differences were statistically significant.(P<0.05).Conclusion:For short-term efficacy,radiofrequency ablation and surgical resection show consistency;for long-term efficacy,surgical resection is more effective.

Research Progress of miRNA Regulating Cell Signaling Pathways Related to Hepatocarcinogenesis

Hepatocellular carcinoma(HCC)is one of the most common malignant tumors in clinical practice.The pathogenesis of HCC is still unclear.Currently,the clinical treatment of HCC is poorly targeted and the therapeutic effect is poor.MicroRNAs(miRNAs)are closely related to the occurrence of HCC,and they are mainly involved in the occurrence and development of HCC through binding to target genes or acting on related signaling pathways.In recent years,studies have shown that miRNA can be used as a potential biomarker for diagnosis and prognosis of HCC.In addition,studies have also shown that miRNA plays a tumorsuppressing or tumor-promoting role in the process of HCC by regulating the biological processes of tumor cell proliferation,migration,invasion and metastasis.In this paper,the recent studies on miRNA signaling pathways related to the occurrence and development of HCC were reviewed,with a view to providing ideas for the clinical diagnosis and treatment of HCC.

Robust Load Frequency Control for Isolated Microgrids Based on Double-loop Compensation

Frequency is an important indicator for the oper-ation of microgrids.However,the randomness and uncertainty of renewable energy and load variability may lead to frequency undulation.So,a robust load frequency control(LFC)is pro-posed for isolated wind-diesel microgrids considering time delay and parameter uncertainty.The control strategy can suppress frequency fuctuation and optimize frequency dynamic response.First,the double compensation loop,including feedforward control and integral sliding mode control(SMC),is devised to provide anti-disturbance compensation for the diesel generator system and ameliorate the frequency stability of independent microgrids.Secondly,a dynamic fuzzy controller,composed of wind speed and load demand,is designed to provide real-time response reference power for doubly fed induction generator systems(DFIGs),which can promote the effective participation of a wind turbine system for frequency regulation.Then,the proportional differential(PD)parameters of a dynamic fuzzy controller and the frequency adjustment compensation of DFIGs can be obtained by using a particle swarm optimization(PSO)algorithm.Thirdly,load demand is an important index of the robust dynamic load frequency control method;the radial basis function(RBF)neural network observer(NNO)based on the LFC model is presented to obtain more accurate load deviations and improve the control precision of LFC.The performance of the proposed LFC method is tested under different operation cases.Index Terms-Load frequency control,microgrid,neural network observer,sliding mode,time delay and parameter uncertainty.

Charge transport mechanism of cross‐linked polyethylene/silicone rubber composite insulation by energy band theory

The composite insulation composed of cross‐linked polyethylene(XLPE)and silicone rubber(SiR)is common in high voltage direct current cable accessory installation.However,the space charge accumulation,especially the interfacial charge accumulation of XLPE/SiR,poses a serious threat to the safe operation of cable accessories,and its charge transport mechanism is still unclear,especially at the micro‐scale.In order to investigate the charge transport mechanism of XLPE/SiR,simultaneous measurement of space charge and relaxation current is performed on XLPE/SiR at various electric fields with different polarities,and the electronic energy levels of XLPE and SiR are determined by quantum chemical calculation(QCC).The results of QCC show that both the hole traps and the electron traps in XLPE are mainly shallow traps.As for SiR,the hole traps are shallow traps,while the electron traps are deep traps.The results of simultaneous measurement show that the interfacial charge accumulation and the composite conductivity of XLPE/SiR are significantly different under different polarities,that is,there is an obvious polarity effect.Based on the results of QCC,the electronic energy levels of XLPE/SiR system are constructed considering the interface between XLPE and SiR,as well as the interfaces between the materials and the electrodes.On this basis,the charge transport mechanism of XLPE/SiR is discussed in detail,and the polarity effect is well explained,which is believed to be related to the differences in the charge injection barrier and the interfacial barrier under different polarities,as well as the electron/hole traps in XLPE and SiR.

Frequency control of a wind-diesel system based on hybrid energy storage

To improve the stability of a wind-diesel hybrid microgrid,a frequency control strategy is designed by using the hybrid energy storage system and the adjustable diesel generator with load frequency control(LFC).The objective of frequency control is to quickly respond to the disturbed system to reduce system frequency deviation and restore stability.By evaluating the area control error,the disturbance state of the system can be divided into four different areas by a corresponding control strategy for precise adjustments.For the diesel generator,an adaptive sliding mode(SM)algorithm is used to design LFC that can participate in frequency modulation.The frequency coordination con-trol strategy proposed in this paper can realize the partition adjustment according to different resources,and ensure frequency stability.The proposed control strategy is verified by RTDS simulations in multiple scenarios.