Larrea divaricata Cav. is a South American plant widely distributed in Argentina with reported antioxidant and antim- icrobial activities. Vitamin C (Vit C) the most important water-soluble antioxidant, is degraded up...Larrea divaricata Cav. is a South American plant widely distributed in Argentina with reported antioxidant and antim- icrobial activities. Vitamin C (Vit C) the most important water-soluble antioxidant, is degraded upon factors such as oxygen, heat, light, storage time and temperature, during cooking and in presence of microorganisms. The aim of this work was: to study the antioxidant and antimicrobial activity of an aqueous extract of L. divaricata (E) on Vit C pre- pared in water and on Vit C from natural orange juice, submitted to different store conditions such as temperatures and oxygen. The antioxidant activity was determined by DPPH method and used to obtained the relative Vit C concentra- tion;Vit C decreased its activity and concentration under temperature and air oxygen, but E allowed Vit C to recover its antioxidant activity and prevented Vit C microorganism contamination. These studies were performed in view to es- tablish whether L. divaricata can be used as a supplement on orange juices capable to prevent Vit C decay and micro- bial growth.展开更多
[Objectives]This study was conducted to explore the physiological mechanism of uniconazole in response to drought stress in Dahlia pinnata.[Methods]With potted seedlings of D.pinnata variety‘Danbanhuang’as an experi...[Objectives]This study was conducted to explore the physiological mechanism of uniconazole in response to drought stress in Dahlia pinnata.[Methods]With potted seedlings of D.pinnata variety‘Danbanhuang’as an experimental material,the effects of different concentrations(10,20,30 and 50 mg/L)of uniconazole on the photosynthetic characteristics of D.pinnata under drought stress and rewatering conditions were discussed.[Results]With the extension of drought time,the chlorophyll SPAD value,net photosynthetic rate,transpiration rate,and stomatal conductance of each treatment group decreased significantly,while the intercellular CO_(2)concentration showed a trend of first decreasing and then increasing;and after pretreatment of uniconazole spraying on leaves,it could alleviate the inhibition of drought stress on the photosynthesis of D.pinnata,and was beneficial to the recovery of photosynthetic capacity of D.pinnata after rewatering,and the effect of leaf application concentration of 30 mg/L was the best.It showed that exogenous uniconazole helps to improve the drought resistance of D.pinnata.[Conclusions]This study provides a new experimental basis for the chemical regulation of stress resistance in D.pinnata and its production and application.展开更多
为提升高速公路通行效率,优化网联自动驾驶车辆(connected and autonomous vehicle,CAV)专用道设置条件下的交织区时空资源配置,以保证CAV高效安全汇入主线专用道,提出了一种基于深度强化学习的交织区集成控制策略。以主线三车道高速公...为提升高速公路通行效率,优化网联自动驾驶车辆(connected and autonomous vehicle,CAV)专用道设置条件下的交织区时空资源配置,以保证CAV高效安全汇入主线专用道,提出了一种基于深度强化学习的交织区集成控制策略。以主线三车道高速公路为研究对象,并设置内侧车道为CAV专用道,设计了充分考虑CAV专用道汇入需求同时兼顾主线通行效率和匝道排队长度的多目标奖励函数,利用深度确定性策略梯度(deep deterministic policy gradient,DDPG)算法实现包括入口匝道信号控制、主线车道级可变限速以及CAV车队间隙调整的集成控制策略,最后使用SUMO和Python搭建高速公路交织区仿真场景,验证所提集成控制策略的有效性。研究结果表明:CAV渗透率为30%时,在低、中、高不同水平交通需求场景下,对比无控制情况集成控制策略可使CAV汇入专用道的纵向位置有所提前,CAV汇入专用道成功率分别增加了19.34%、22.86%、25.55%;此外,车辆平均行程时间也分别降低了5.42%、17.41%、20.65%。所提出的交织区集成控制策略效果显著,不仅实现了CAV汇入专用道的有效引导,还提升了主线的通行效率及运行安全,为改善CAV专用道设置条件下高速公路交织区交通运行状况提供了理论依据和技术参考。展开更多
城市快速路作为重要交通走廊,其合流区交通调度更为复杂。为保障智能网联车辆(Connected and Automated Vehicle, CAV)在城市快速路合流区高效、安全、舒适行驶,基于城市快速路合流区的换道特征,开展了考虑换道风险动态评估结果的CAV换...城市快速路作为重要交通走廊,其合流区交通调度更为复杂。为保障智能网联车辆(Connected and Automated Vehicle, CAV)在城市快速路合流区高效、安全、舒适行驶,基于城市快速路合流区的换道特征,开展了考虑换道风险动态评估结果的CAV换道决策模型的相关研究。首先,对换道车辆与邻车进行时空重叠分析,将分析结果作为潜在风险判别依据,对存在时空重叠的CAV及其邻车计算换道碰撞时间(Lane Change Time to Collision, LCTTC),实现换道风险动态评估;然后,将换道风险动态评估结果融入多目标奖励函数优化的DQN(Deep Q-Network)网络结构,并综合考虑车辆行驶高效性、安全性与舒适性等因素,提出具有风险感知的SIDQN(Security Improvement Deep Q-Network)换道决策;最后,通过仿真试验进行验证。研究结果表明:相较于对比策略,提出的SIDQN策略换道成功率保持在95%以上,且运行平均速度不低于21.008 m·s^(-1);此外,在复杂的交通合流场景中,融入安全性奖励的SIDQN策略表现出最佳安全性,其LCTTC平均占比仅为9.56%,远低于其他对比策略,同时事故率统计结果持续保持较低水平;在舒适性方面,SIDQN策略下换道次数仅为4次,连续换道和无效换道次数均为1次,并显著降低了频繁换道和极端加速减速操作次数,提升了乘客的舒适体验。提出的换道决策模型综合性能优势明显,可为智能网联环境下城市快速路合流区CAV安全换道决策研究提供参考。展开更多
文摘Larrea divaricata Cav. is a South American plant widely distributed in Argentina with reported antioxidant and antim- icrobial activities. Vitamin C (Vit C) the most important water-soluble antioxidant, is degraded upon factors such as oxygen, heat, light, storage time and temperature, during cooking and in presence of microorganisms. The aim of this work was: to study the antioxidant and antimicrobial activity of an aqueous extract of L. divaricata (E) on Vit C pre- pared in water and on Vit C from natural orange juice, submitted to different store conditions such as temperatures and oxygen. The antioxidant activity was determined by DPPH method and used to obtained the relative Vit C concentra- tion;Vit C decreased its activity and concentration under temperature and air oxygen, but E allowed Vit C to recover its antioxidant activity and prevented Vit C microorganism contamination. These studies were performed in view to es- tablish whether L. divaricata can be used as a supplement on orange juices capable to prevent Vit C decay and micro- bial growth.
基金Applied Basic Research Program of Suzhou City(SYN201405).
文摘[Objectives]This study was conducted to explore the physiological mechanism of uniconazole in response to drought stress in Dahlia pinnata.[Methods]With potted seedlings of D.pinnata variety‘Danbanhuang’as an experimental material,the effects of different concentrations(10,20,30 and 50 mg/L)of uniconazole on the photosynthetic characteristics of D.pinnata under drought stress and rewatering conditions were discussed.[Results]With the extension of drought time,the chlorophyll SPAD value,net photosynthetic rate,transpiration rate,and stomatal conductance of each treatment group decreased significantly,while the intercellular CO_(2)concentration showed a trend of first decreasing and then increasing;and after pretreatment of uniconazole spraying on leaves,it could alleviate the inhibition of drought stress on the photosynthesis of D.pinnata,and was beneficial to the recovery of photosynthetic capacity of D.pinnata after rewatering,and the effect of leaf application concentration of 30 mg/L was the best.It showed that exogenous uniconazole helps to improve the drought resistance of D.pinnata.[Conclusions]This study provides a new experimental basis for the chemical regulation of stress resistance in D.pinnata and its production and application.
文摘城市快速路作为重要交通走廊,其合流区交通调度更为复杂。为保障智能网联车辆(Connected and Automated Vehicle, CAV)在城市快速路合流区高效、安全、舒适行驶,基于城市快速路合流区的换道特征,开展了考虑换道风险动态评估结果的CAV换道决策模型的相关研究。首先,对换道车辆与邻车进行时空重叠分析,将分析结果作为潜在风险判别依据,对存在时空重叠的CAV及其邻车计算换道碰撞时间(Lane Change Time to Collision, LCTTC),实现换道风险动态评估;然后,将换道风险动态评估结果融入多目标奖励函数优化的DQN(Deep Q-Network)网络结构,并综合考虑车辆行驶高效性、安全性与舒适性等因素,提出具有风险感知的SIDQN(Security Improvement Deep Q-Network)换道决策;最后,通过仿真试验进行验证。研究结果表明:相较于对比策略,提出的SIDQN策略换道成功率保持在95%以上,且运行平均速度不低于21.008 m·s^(-1);此外,在复杂的交通合流场景中,融入安全性奖励的SIDQN策略表现出最佳安全性,其LCTTC平均占比仅为9.56%,远低于其他对比策略,同时事故率统计结果持续保持较低水平;在舒适性方面,SIDQN策略下换道次数仅为4次,连续换道和无效换道次数均为1次,并显著降低了频繁换道和极端加速减速操作次数,提升了乘客的舒适体验。提出的换道决策模型综合性能优势明显,可为智能网联环境下城市快速路合流区CAV安全换道决策研究提供参考。
