AIM: To study the core cell damage in isolated islets of Langerhans and its prevention by low temperature preconditioning (26 ℃).METHODS: Islets were cultured at 37 ℃ for 7-14 d after isolation, and then at 26 ℃ fo...AIM: To study the core cell damage in isolated islets of Langerhans and its prevention by low temperature preconditioning (26 ℃).METHODS: Islets were cultured at 37 ℃ for 7-14 d after isolation, and then at 26 ℃ for 2, 4 and 7 d before additional culture at 37 ℃ for another 7 d. Core cell damage in the isolated islets was monitored by video-microscopy and analyzed quantitatively by use of a computer-assisted image analysis system. The analysis included daily measurement of the diameter and the area of the isolated islets and the area of the core cell damage that developed in those islets over time during culture. Histology and TdT-mediated dUTP-biotin nick end labeling (TUNEL) assay were used to characterize the cell damage and to monitor islet function.RESULTS: Microscopic analysis showed that during the 7 to 14 d of culture at 37 ℃, core cell damage occurred in the larger islets with diameters ＞200 μm, which included both necrotic and apoptotic cell death. Low temperature (26 ℃) culture could prevent core cell damage of isolated islets. The 7-d culture procedure at 26 ℃ could inhibit most of the core cell (excluding diameters＞300 μm) damages when the islets were re-warmed at 37 ℃.CONCLUSION: Our results indicate that core cell damage within isolated islets of Langerhans correlates with the size of islets. Low temperature (26 ℃) culture can prevent core cell damage in isolated islets, and successfully precondition these islets for incubation at 37 ℃. These novel findings may help to understand the pathophysiology of early loss of islet tissue after transplantation, and may provide a new strategy to improve graft function in the clinical setting of islet transplantation.展开更多
This study aimed to investigate the performance evolution characteristics of concrete under permafrost ambient temperatures and to explore methods to mitigate the thermal perturbation by concrete on the permafrost env...This study aimed to investigate the performance evolution characteristics of concrete under permafrost ambient temperatures and to explore methods to mitigate the thermal perturbation by concrete on the permafrost environment.A program was designed to investigate the properties of various concretes at three curing conditions.The compressive strength development pattern of each group was evaluated and the concrete's performance was characterized by compressive strength damage degree,hydration temperature and SEM analysis in a low temperature environment.The experimental results show that the incorporation of fly ash alone or incombination with other admixtures in concrete under low-temperature curing does not deteriorate its microstructure,and at the same time,it can slow down the hydration rate of cement and significantly reduce the exothermic heat of hydration of concrete.These findings are expected to provide valuable references for the proportioning design of concrete in permafrost environments.展开更多
实验室进行了4种不同酸溶液的破胶实验,应用旋转黏度计、马尔文激光粒度仪、离心机、分光光度计等多手段测定了破胶液的黏度、残渣粒径分布、残渣含量及滤液中的含糖量,优选出了适用于低温煤储层的破胶剂。实验测试评价了该破胶液对煤...实验室进行了4种不同酸溶液的破胶实验,应用旋转黏度计、马尔文激光粒度仪、离心机、分光光度计等多手段测定了破胶液的黏度、残渣粒径分布、残渣含量及滤液中的含糖量,优选出了适用于低温煤储层的破胶剂。实验测试评价了该破胶液对煤储层的伤害性。结果表明:温度20℃时HXM+NH_4Cl复合酸破胶效果好,浓度越大破胶速度越快。使用浓度0.10%HXM+0.05%NH_4Cl的酸液进行破胶,2 h内压裂液黏度可降到5 m Pa·s以下,破胶液残渣中值粒径为86μm,残渣含量70 mg/L。原始渗透率小于0.87×10^(-15)m^2时,煤芯渗透率的伤害率小于20%;煤储层的原始渗透率越大,破胶液对岩芯的伤害率越大。该复合酸破胶剂与常规氧化破胶剂相比,具有低温下破胶彻底、残渣含量少、伤害轻等优点。展开更多
为了动态提高三芯电缆的实时载流量以及保证电缆安全稳定运行,对影响三芯电缆线芯温度的两个主要因素进行了分析,通过利用生物学中局部灵敏度的概念,分析了环境热阻与环境温度对三芯电缆线芯温度的影响。同时,搭建了10 k V三芯电缆载流...为了动态提高三芯电缆的实时载流量以及保证电缆安全稳定运行,对影响三芯电缆线芯温度的两个主要因素进行了分析,通过利用生物学中局部灵敏度的概念,分析了环境热阻与环境温度对三芯电缆线芯温度的影响。同时,搭建了10 k V三芯电缆载流量试验场,并模拟了空气敷设和土壤敷设下的三芯电缆温升试验。理论分析与实验结果可得:空气敷设时,随着加载电流的增大,环境热阻对电缆线芯温度的灵敏度增加,且都处于灵敏等级;土壤敷设时,环境热阻对电缆线芯温度的灵敏度处于不灵敏等级;同一加载电流下,外界环境热阻的变化对于电缆线芯温度的影响很大。两种不同敷设情况下,当三芯电缆线芯温度相等时,相比空气敷设情况,加载电流为200 A,土壤敷设时,电缆载流量可以提高3.6%;加载电流为300 A,土壤敷设时,电缆载流量可以提高8.1%;加载电流为400 A,土壤敷设时,电缆载流量可以提高9.2%;加载电流为500 A,土壤敷设时,电缆载流量可以提高22.3%。当三芯电缆运行状态未达到稳定时,电缆线芯温度主要由加载电流的大小决定;当三芯电缆运行状态达到稳定时,电缆线芯温度的变化趋势与环境温度变化趋势基本相同,线芯温度由敷设环境温度决定。展开更多
基金Supported by the National Natural Science Foundation of China, No.30271274 German DAAD-Wong Kuan Cheng Fellowship
文摘AIM: To study the core cell damage in isolated islets of Langerhans and its prevention by low temperature preconditioning (26 ℃).METHODS: Islets were cultured at 37 ℃ for 7-14 d after isolation, and then at 26 ℃ for 2, 4 and 7 d before additional culture at 37 ℃ for another 7 d. Core cell damage in the isolated islets was monitored by video-microscopy and analyzed quantitatively by use of a computer-assisted image analysis system. The analysis included daily measurement of the diameter and the area of the isolated islets and the area of the core cell damage that developed in those islets over time during culture. Histology and TdT-mediated dUTP-biotin nick end labeling (TUNEL) assay were used to characterize the cell damage and to monitor islet function.RESULTS: Microscopic analysis showed that during the 7 to 14 d of culture at 37 ℃, core cell damage occurred in the larger islets with diameters ＞200 μm, which included both necrotic and apoptotic cell death. Low temperature (26 ℃) culture could prevent core cell damage of isolated islets. The 7-d culture procedure at 26 ℃ could inhibit most of the core cell (excluding diameters＞300 μm) damages when the islets were re-warmed at 37 ℃.CONCLUSION: Our results indicate that core cell damage within isolated islets of Langerhans correlates with the size of islets. Low temperature (26 ℃) culture can prevent core cell damage in isolated islets, and successfully precondition these islets for incubation at 37 ℃. These novel findings may help to understand the pathophysiology of early loss of islet tissue after transplantation, and may provide a new strategy to improve graft function in the clinical setting of islet transplantation.
基金Funded by the National Natural Science Foundation of China(Nos.52068035,52078372,and 52478272)。
文摘This study aimed to investigate the performance evolution characteristics of concrete under permafrost ambient temperatures and to explore methods to mitigate the thermal perturbation by concrete on the permafrost environment.A program was designed to investigate the properties of various concretes at three curing conditions.The compressive strength development pattern of each group was evaluated and the concrete's performance was characterized by compressive strength damage degree,hydration temperature and SEM analysis in a low temperature environment.The experimental results show that the incorporation of fly ash alone or incombination with other admixtures in concrete under low-temperature curing does not deteriorate its microstructure,and at the same time,it can slow down the hydration rate of cement and significantly reduce the exothermic heat of hydration of concrete.These findings are expected to provide valuable references for the proportioning design of concrete in permafrost environments.
文摘实验室进行了4种不同酸溶液的破胶实验,应用旋转黏度计、马尔文激光粒度仪、离心机、分光光度计等多手段测定了破胶液的黏度、残渣粒径分布、残渣含量及滤液中的含糖量,优选出了适用于低温煤储层的破胶剂。实验测试评价了该破胶液对煤储层的伤害性。结果表明:温度20℃时HXM+NH_4Cl复合酸破胶效果好,浓度越大破胶速度越快。使用浓度0.10%HXM+0.05%NH_4Cl的酸液进行破胶,2 h内压裂液黏度可降到5 m Pa·s以下,破胶液残渣中值粒径为86μm,残渣含量70 mg/L。原始渗透率小于0.87×10^(-15)m^2时,煤芯渗透率的伤害率小于20%;煤储层的原始渗透率越大,破胶液对岩芯的伤害率越大。该复合酸破胶剂与常规氧化破胶剂相比,具有低温下破胶彻底、残渣含量少、伤害轻等优点。
