Most existing media access control(MAC) protocols in power line communication(PLC) networks just discard the colliding data packets when collision occurs.The collision deteriorates throughput and delay performance of ...Most existing media access control(MAC) protocols in power line communication(PLC) networks just discard the colliding data packets when collision occurs.The collision deteriorates throughput and delay performance of system under high traffic conditions.This article presents a novel media access scheme with fast collision resolution for in-home power line networks.It works by first recognizing the colliding stations through detecting the inserted unique ID sequence ahead of data packets,then the source nodes retransmitting their packets immediately after the collision slot.The proposed protocol maintains the benefits of ALOHA systems.It needs no scheduling overhead and is suitable for bursty sources,such as multimedia data packets.Computer simulations have demonstrated that this approach can achieve high throughput due to its ability of resolving collisions.展开更多
文摘目的 利用生物信息学方法预测分析铁死亡相关蛋白SLC7A11的理化、结构及抗原表位等性质并检测SLC7A11与GPX4在热射病(heat stroke,HS)大鼠心肌组织及H9C2心肌细胞中的表达水平,为临床中热射病的治疗提供新的潜在靶点。方法 利用多种工具预测分析SLC7A11蛋白的基本理化性质、信号肽跨膜区和跨膜结构域、蛋白质翻译后的磷酸化位点和N-糖基化位点、二级结构和三级结构、SLC7A11的抗原决定簇及与其相互作用的蛋白。体内实验分为对照组(n=6)、HS组(n=6),体外实验分为对照组、铁死亡抑制剂(Liproxstatin-1)组、HS组和HS+Liproxstatin-1组。利用Western blot和RT-qPCR检测大鼠心肌组织与H9C2心肌细胞中SLC7A11、GPX4 m RNA和蛋白水平。结果 SLC7A11为稳定疏水性蛋白,预测在第29~30位氨基酸存在信号肽,并含12个跨膜螺旋结构;SLC7A11存在40个磷酸化位点、12个N-糖基化位点;SLC7A11蛋白的二、三级结构主要由α螺旋、β-折叠及无规卷曲构成;SLC7A11含有15个抗原决定簇区域;SLC7A11可与GPX4等蛋白相互作用;与对照组比较,HS组大鼠心肌组织中SLC7A11(P<0.05)和GPX4(P<0.01)mRNA和蛋白质表达均降低;Liproxstatin-1组与对照组H9C2心肌细胞中SLC7A11和GPX4 m RNA和蛋白水平比较差异无统计学意义(P均>0.05),HS组SLC7A11与GPX4 m RNA和蛋白水平降低(P均<0.01);与HS组相比,HS+Liproxstatin-1组SLC7A11(P<0.05)和GPX4(P<0.01)m RNA和蛋白水平均有所改善。结论 SLC7A11为疏水性跨膜蛋白,存在大量磷酸化和N-糖基化位点,并含有15个抗原决定簇。HS大鼠心肌组织与高温干预的H9C2心肌细胞中铁死亡相关蛋白SLC7A11与GPX4表达减少,在细胞水平加入铁死亡抑制剂Liproxstatin-1后,SLC7A11与GPX4表达得到改善。
文摘Most existing media access control(MAC) protocols in power line communication(PLC) networks just discard the colliding data packets when collision occurs.The collision deteriorates throughput and delay performance of system under high traffic conditions.This article presents a novel media access scheme with fast collision resolution for in-home power line networks.It works by first recognizing the colliding stations through detecting the inserted unique ID sequence ahead of data packets,then the source nodes retransmitting their packets immediately after the collision slot.The proposed protocol maintains the benefits of ALOHA systems.It needs no scheduling overhead and is suitable for bursty sources,such as multimedia data packets.Computer simulations have demonstrated that this approach can achieve high throughput due to its ability of resolving collisions.