Ostreopsis cf.ovata is a marine benthic dinoflagellate in tropical and temperate seas and can produce potent toxic compounds.The existence of O.cf.ovata has been found in the Chinese coastal areas,but studies on its t...Ostreopsis cf.ovata is a marine benthic dinoflagellate in tropical and temperate seas and can produce potent toxic compounds.The existence of O.cf.ovata has been found in the Chinese coastal areas,but studies on its toxicity are very few.This study investigated the toxicity of the O.cf.ovata(TIO991)isolated from Weizhou Island in the South China Sea by using methanol and chloroform to extract toxic compounds from the algal cells cultured indoor.Experiments on mouse acute toxicity showed that the crude methanol extract(CME)of O.cf.ovata caused the death of mice in 16–18 min.Furthermore,CME inhibited the cell reproduction of human neuroblastoma cells(BE(2)-M17 cells)by Cell Counting Kit-8 with a dose-and time-effect relationship and caused cell death in the form of cell necrosis.We found that CME had strong hemolytic activity and was significantly inhibited by ouabain,indicating that CME might contain palytoxins.By contrast,the crude chloroform extract of O.cf.ovata was relatively weak in toxicity as obtained in our experiments on mouse acute toxicity,cytotoxicity,and hemolytic activity.This suggests that the algae may raise the potential threat to marine ecosystems and public health.展开更多
功率变换器采用脉宽调制时产生的高共模电压CMV(common-mode voltage)会使电机轴电压过高,进而导致高频高幅值轴电流破坏电机绝缘、增加电磁干扰等。为减小中点钳位型NPC(neutral point clamped)三电平变换器的共模电压,提出了基于代数...功率变换器采用脉宽调制时产生的高共模电压CMV(common-mode voltage)会使电机轴电压过高,进而导致高频高幅值轴电流破坏电机绝缘、增加电磁干扰等。为减小中点钳位型NPC(neutral point clamped)三电平变换器的共模电压,提出了基于代数调制框架的共模电压抑制策略:首先,将占空比的确定问题转化为非齐次线性方程组的求解问题;然后,合理地选择调制自由度以实现中点电压NPV(neutral point voltage)平衡控制的目标;其次,根据占空比约束,选择偏置量获取最终占空比;最后,使中间相开关采用反相载波得到新的开关状态组合,实现降低共模电压的目的。所提调制策略无需额外的控制器,实现简单,在保证中点钳位型三电平变换器的中点电压具有良好平衡特性的前提下,可将共模电压降低至直流侧电压的1/6范围内。实验结果验证了所提调制策略的有效性和可行性。展开更多
In order to survey the infectious situation of canine coronavirus (CCV) in giant panda population, a virus neutralization test detecting specific antibodies against CCV in giant panda抯 sera was established by using t...In order to survey the infectious situation of canine coronavirus (CCV) in giant panda population, a virus neutralization test detecting specific antibodies against CCV in giant panda抯 sera was established by using two-fold dilutions of serum and 100 TCID50 of the virus. The 62 sera samples of giant pandas, which were gathered from zoos and reserve region of Sichuan Province, China were detected. The neutralization antibody titer of 1:4 was recognized as the positive criterion, 8 sera samples were detected to be positive, and the positive rate was 12.9%. The titers of neutralizing antibody ranged from 1:8 to 1:32. It was the first comprehensive investigation on neutralization antibodies against CCV in giant panda population in China. The results of study showed that the infection of CCV in giant panda population was universal, which has posed a threat to the health of giant panda. Therefore, it is incumbent on us to study safe and effective vaccines to protect giant panda against CCV infection.展开更多
基金Supported by the Special Research for the Science and Technology Basic Resources Investigation Program of China(No.2018FY100200)the National Natural Science Foundation of China(No.42176206)the Natural Science Foundation of Shandong Province(No.ZR2021MD071)。
文摘Ostreopsis cf.ovata is a marine benthic dinoflagellate in tropical and temperate seas and can produce potent toxic compounds.The existence of O.cf.ovata has been found in the Chinese coastal areas,but studies on its toxicity are very few.This study investigated the toxicity of the O.cf.ovata(TIO991)isolated from Weizhou Island in the South China Sea by using methanol and chloroform to extract toxic compounds from the algal cells cultured indoor.Experiments on mouse acute toxicity showed that the crude methanol extract(CME)of O.cf.ovata caused the death of mice in 16–18 min.Furthermore,CME inhibited the cell reproduction of human neuroblastoma cells(BE(2)-M17 cells)by Cell Counting Kit-8 with a dose-and time-effect relationship and caused cell death in the form of cell necrosis.We found that CME had strong hemolytic activity and was significantly inhibited by ouabain,indicating that CME might contain palytoxins.By contrast,the crude chloroform extract of O.cf.ovata was relatively weak in toxicity as obtained in our experiments on mouse acute toxicity,cytotoxicity,and hemolytic activity.This suggests that the algae may raise the potential threat to marine ecosystems and public health.
文摘功率变换器采用脉宽调制时产生的高共模电压CMV(common-mode voltage)会使电机轴电压过高,进而导致高频高幅值轴电流破坏电机绝缘、增加电磁干扰等。为减小中点钳位型NPC(neutral point clamped)三电平变换器的共模电压,提出了基于代数调制框架的共模电压抑制策略:首先,将占空比的确定问题转化为非齐次线性方程组的求解问题;然后,合理地选择调制自由度以实现中点电压NPV(neutral point voltage)平衡控制的目标;其次,根据占空比约束,选择偏置量获取最终占空比;最后,使中间相开关采用反相载波得到新的开关状态组合,实现降低共模电压的目的。所提调制策略无需额外的控制器,实现简单,在保证中点钳位型三电平变换器的中点电压具有良好平衡特性的前提下,可将共模电压降低至直流侧电压的1/6范围内。实验结果验证了所提调制策略的有效性和可行性。
基金This research was supported by National Science Founda-tion of China (No. 30000123) and Conversation Department of Wildlife Ani-mal & Plants of State Forestry Bureau.
文摘In order to survey the infectious situation of canine coronavirus (CCV) in giant panda population, a virus neutralization test detecting specific antibodies against CCV in giant panda抯 sera was established by using two-fold dilutions of serum and 100 TCID50 of the virus. The 62 sera samples of giant pandas, which were gathered from zoos and reserve region of Sichuan Province, China were detected. The neutralization antibody titer of 1:4 was recognized as the positive criterion, 8 sera samples were detected to be positive, and the positive rate was 12.9%. The titers of neutralizing antibody ranged from 1:8 to 1:32. It was the first comprehensive investigation on neutralization antibodies against CCV in giant panda population in China. The results of study showed that the infection of CCV in giant panda population was universal, which has posed a threat to the health of giant panda. Therefore, it is incumbent on us to study safe and effective vaccines to protect giant panda against CCV infection.
