AIM To study sex disparity in susceptibility to hepatocellular carcinoma(HCC), we created a transgenic mouse model that expressed the full hepatitis B virus(HBV) genome with the W4P mutation.METHODS Transgenic mice we...AIM To study sex disparity in susceptibility to hepatocellular carcinoma(HCC), we created a transgenic mouse model that expressed the full hepatitis B virus(HBV) genome with the W4P mutation.METHODS Transgenic mice were generated by transferring the p HY92-1.1 x-HBV-full genome plasmid(genotype A2) into C57 Bl/6 N mice. We compared serum levels of hepatitis B surface antigen(HBs Ag), interleukin(IL)-6, and the liver enzymes alanine aminotransferase(ALT) and aspartate transaminase(AST), as well as liver histopathological features in male and female transgenic(W4PTG) mice and in nontransgenic littermates of 10 mo of age. RESULTS W4PTG males exhibited more pronounced hepatomegaly, significantly increased granule generation in liver tissue, elevated HBs Ag expression in the liver and serum, and higher serum ALT and IL-6 levels compared to W4PTG females or littermate control groups. CONCLUSION Together, our data indicate that the W4 P mutation in pre S1 may contribute to sex disparity in susceptibility to HCC by causing increased HBV virion replication and enhanced IL-6-mediated inflammation in male individuals. Additionally, our transgenic mouse model that expresses full HBV genome with the W4 P mutation in pre S1 could be effectively used for the studies of the progression of liver diseases, including HCC.展开更多
Hardness, friction and wear characteristics of electrodeposited RE Ni W P B 4C PTFE composite coatings were studied, and the reason for these fine characteristics was explained in respect of structure. The results sho...Hardness, friction and wear characteristics of electrodeposited RE Ni W P B 4C PTFE composite coatings were studied, and the reason for these fine characteristics was explained in respect of structure. The results show that 1) the structure of RE Ni W P B 4C PTFE composite coatings experiences a transformation process from amorphous to mixture then to crystal as the heat treatment temperature rises; 2) incorporating of B 4C greatly increases the hardness of the coating; 3) the wear resistance of the coating is best with heat treatment for 1?h at 300?℃, which is greatly superior to that of the other traditional coatings.展开更多
The coordinated control of parallel three-phase fourwire converters in autonomous AC microgrids is investigated in this paper.First,based on droop control,virtual impedance is inserted in positive-,negative-and zero-s...The coordinated control of parallel three-phase fourwire converters in autonomous AC microgrids is investigated in this paper.First,based on droop control,virtual impedance is inserted in positive-,negative-and zero-sequences to enhance system damping and imbalance power sharing.Then,to facilitate virtual impedance design,small signal models of the three-sequence equivalent circuits are established respectively.Corresponding indexes are proposed to comprehensively evaluate the impact of sequence virtual impedance on current sharing accuracy,voltage quality at the point of common coupling(PCC)and system stability.In addition,constraint of DClink voltage is also considered to avoid over modulation when subjected to unbalanced loads.Furthermore,to address the PCC voltage degradation resulting from virtual impedance,a voltage imbalance compensation method,based on low-bandwidth communication,is proposed.Finally,simulation and experimental results are provided to verify the correctness of the theory model,indicating that the proposed method can achieve PCC voltage restoration while guaranteeing the current sharing accuracy with desirable dynamics.展开更多
We propose a modular multilevel converter(MMC)based three-phase four-wire(3P4W)split capacitor distribution static synchronous compensator(DSTATCOM),aiming at compensating unbalanced and reactive load currents.Due to ...We propose a modular multilevel converter(MMC)based three-phase four-wire(3P4W)split capacitor distribution static synchronous compensator(DSTATCOM),aiming at compensating unbalanced and reactive load currents.Due to the zero-sequence current compensation,the circulating current char-acteristics of 3P4W MMC-DSTATCOM are different from conventional MMCs.Moreover,the distinct working principle of IMMC would affect the features of split capacitor voltage.The decoupled positive-,negative-and zero-sequence second-order and DC components of the circulating current are deduced explicitly.Two proportional-integral controllers with dual dq transformation are employed to suppress the positive-and negative-sequence components of second-order circulating current,while quasi proportional-resonance controller is designed to eliminate the zero-sequence component.Besides,the phenomenon of the unbalanced split capacitor voltages is revealed,and fast-tracking balancing method by controlling zero-sequence current flowing through the split capacitors is provided.Digital simulation results verify the accuracy of the analysis and the feasibility of the suppression methods.展开更多
基金Supported by the Korea Health Technology R&D Project through the Korea Health Industry Development Institute and the Ministry of Health and Welfare,South Korea,No.HI14C0955
文摘AIM To study sex disparity in susceptibility to hepatocellular carcinoma(HCC), we created a transgenic mouse model that expressed the full hepatitis B virus(HBV) genome with the W4P mutation.METHODS Transgenic mice were generated by transferring the p HY92-1.1 x-HBV-full genome plasmid(genotype A2) into C57 Bl/6 N mice. We compared serum levels of hepatitis B surface antigen(HBs Ag), interleukin(IL)-6, and the liver enzymes alanine aminotransferase(ALT) and aspartate transaminase(AST), as well as liver histopathological features in male and female transgenic(W4PTG) mice and in nontransgenic littermates of 10 mo of age. RESULTS W4PTG males exhibited more pronounced hepatomegaly, significantly increased granule generation in liver tissue, elevated HBs Ag expression in the liver and serum, and higher serum ALT and IL-6 levels compared to W4PTG females or littermate control groups. CONCLUSION Together, our data indicate that the W4 P mutation in pre S1 may contribute to sex disparity in susceptibility to HCC by causing increased HBV virion replication and enhanced IL-6-mediated inflammation in male individuals. Additionally, our transgenic mouse model that expresses full HBV genome with the W4 P mutation in pre S1 could be effectively used for the studies of the progression of liver diseases, including HCC.
文摘Hardness, friction and wear characteristics of electrodeposited RE Ni W P B 4C PTFE composite coatings were studied, and the reason for these fine characteristics was explained in respect of structure. The results show that 1) the structure of RE Ni W P B 4C PTFE composite coatings experiences a transformation process from amorphous to mixture then to crystal as the heat treatment temperature rises; 2) incorporating of B 4C greatly increases the hardness of the coating; 3) the wear resistance of the coating is best with heat treatment for 1?h at 300?℃, which is greatly superior to that of the other traditional coatings.
文摘The coordinated control of parallel three-phase fourwire converters in autonomous AC microgrids is investigated in this paper.First,based on droop control,virtual impedance is inserted in positive-,negative-and zero-sequences to enhance system damping and imbalance power sharing.Then,to facilitate virtual impedance design,small signal models of the three-sequence equivalent circuits are established respectively.Corresponding indexes are proposed to comprehensively evaluate the impact of sequence virtual impedance on current sharing accuracy,voltage quality at the point of common coupling(PCC)and system stability.In addition,constraint of DClink voltage is also considered to avoid over modulation when subjected to unbalanced loads.Furthermore,to address the PCC voltage degradation resulting from virtual impedance,a voltage imbalance compensation method,based on low-bandwidth communication,is proposed.Finally,simulation and experimental results are provided to verify the correctness of the theory model,indicating that the proposed method can achieve PCC voltage restoration while guaranteeing the current sharing accuracy with desirable dynamics.
基金This work was supported in part by the National Natural Science Foundation of China(No.51807073).
文摘We propose a modular multilevel converter(MMC)based three-phase four-wire(3P4W)split capacitor distribution static synchronous compensator(DSTATCOM),aiming at compensating unbalanced and reactive load currents.Due to the zero-sequence current compensation,the circulating current char-acteristics of 3P4W MMC-DSTATCOM are different from conventional MMCs.Moreover,the distinct working principle of IMMC would affect the features of split capacitor voltage.The decoupled positive-,negative-and zero-sequence second-order and DC components of the circulating current are deduced explicitly.Two proportional-integral controllers with dual dq transformation are employed to suppress the positive-and negative-sequence components of second-order circulating current,while quasi proportional-resonance controller is designed to eliminate the zero-sequence component.Besides,the phenomenon of the unbalanced split capacitor voltages is revealed,and fast-tracking balancing method by controlling zero-sequence current flowing through the split capacitors is provided.Digital simulation results verify the accuracy of the analysis and the feasibility of the suppression methods.
