异地站点之间需要在广域范围实现时间同步。除了采用卫星授时外,希望借助SDH(Synchronous Digital Hierarchy)网络进行时间同步性能的在线监测。但是广域范围内的SDH网络结构复杂、跳数较多,且大量存在上下行线路不对称的现象,对传统网...异地站点之间需要在广域范围实现时间同步。除了采用卫星授时外,希望借助SDH(Synchronous Digital Hierarchy)网络进行时间同步性能的在线监测。但是广域范围内的SDH网络结构复杂、跳数较多,且大量存在上下行线路不对称的现象,对传统网络时间同步技术提出了挑战。因此,针对广域SDH网络,提出了基于WR PTP(White Rabbit Precision Timing Protocol)技术的链路模型。该模型考虑了SDH网络中存在的各个延时环节及其计算方法,并针对实际网络中存在的不对称链路时延,给出了修正方法,推导了时钟偏差的修正计算公式。同时对于SDH环网中存在的链路倒换问题,给出了工程化解决方法。所提各方法在实际的SDH网络上进行了测试,结果表明,能达到的时间同步误差不超过1μs,可满足广域时间同步及时钟同步性能在线监测的需要。展开更多
针对PTP(precise time protocol)协议在应用层获取软件时间戳导致时钟同步精度下降的问题,提出一种基于MAC(media access control)层获取硬件时间戳的PTP同步优化方案。设计了以STM32F407微处理器为核心的PTP时钟应用平台,在MAC层实现...针对PTP(precise time protocol)协议在应用层获取软件时间戳导致时钟同步精度下降的问题,提出一种基于MAC(media access control)层获取硬件时间戳的PTP同步优化方案。设计了以STM32F407微处理器为核心的PTP时钟应用平台,在MAC层实现了硬件时间戳获取,避免了由于协议栈软件处理延时产生的不确定性;针对PTP时钟晶振老化导致的时间同步偏差及网络延迟抖动问题,采用迭代方法优化了本地时钟频率调节算法,提高了频率校正精度。经实际测试,主从时钟偏差的RMS(root mean square)优于20 ns,提升了时钟同步精度。展开更多
Eight previously undescribed lanostane triterpenoids,including five nortriterpenoids with 26carbons,ganothenoids A-E(1-5),and three lanostanoids,ganothenoids F-H(6-8),along with 24 known ones(9-32),were isolated from ...Eight previously undescribed lanostane triterpenoids,including five nortriterpenoids with 26carbons,ganothenoids A-E(1-5),and three lanostanoids,ganothenoids F-H(6-8),along with 24 known ones(9-32),were isolated from the fruiting bodies of Ganodrma theaecolum.The structures of the novel compounds were elucidated using comprehensive spectroscopic methods,including electronic circular dichroism(ECD)and nuclear magnetic resonance(NMR)calculations.Compounds 1-32 were assessed for their neuroprotective effects against H_(2)O_(2)-induced damage in human neuroblastoma SH-SY5Y cells,as well as their inhibitory activities against protein tyrosine phosphatase 1B(PTP1B)andα-glucosidase.Compound 4demonstrated the most potent neuroprotective activity against H_(2)O_(2)-induced oxidative stress by suppressing G_0/G_1 phase cell cycle arrest,reducing reactive oxygen species(ROS)levels,and inhibiting cell apoptosis through modulation of B-cell lymphoma 2 protein(Bcl-2)and Bcl-2 associated X-protein(Bax)protein expression.Compounds 26,12,and 28 exhibited PTP1B inhibitory activities with IC_(50)values ranging from 13.92 to 56.94μmol·L~(-1),while compound12 alone displayed significant inhibitory effects onα-glucosidase with an IC_(50)value of 43.56μmol·L~(-1).Additionally,enzyme kinetic analyses and molecular docking simulations were conducted for compounds 26 and 12 with PTP1B andα-glucosidase,respectively.展开更多
The SH2 domain-containing protein tyrosine phosphatase 2(SHP2,also known as PTP2C),encoded by PTPN11,is ubiquitously expressed and has context-specific effects.It promotes RAS/MAPK signaling downstream of receptor tyr...The SH2 domain-containing protein tyrosine phosphatase 2(SHP2,also known as PTP2C),encoded by PTPN11,is ubiquitously expressed and has context-specific effects.It promotes RAS/MAPK signaling downstream of receptor tyrosine kinases,cytokine receptors,and extracellular matrix proteins,and was shown in various lineages to modulate cell survival,proliferation,differentiation,and migration.Over the past decade,PTPN11 inactivation in chondrocytes was found to cause metachondromatosis,a rare disorder characterized by multiple enchondromas and osteochondroma-like lesions.Moreover,SHP2 inhibition was found to mitigate osteoarthritis pathogenesis in mice,and abundant but incomplete evidence suggests that SHP2 is crucial for cartilage development and adult homeostasis,during which its expression and activity are tightly regulated transcriptionally and posttranslationally,and by varying sets of functional partners.Fully uncovering SHP2 actions and regulation in chondrocytes is thus fundamental to understanding the mechanisms underlying both rare and common cartilage diseases and to designing effective disease treatments.We here review current knowledge,highlight recent discoveries and controversies,and propose new research directions to answer remaining questions.展开更多
文摘针对PTP(precise time protocol)协议在应用层获取软件时间戳导致时钟同步精度下降的问题,提出一种基于MAC(media access control)层获取硬件时间戳的PTP同步优化方案。设计了以STM32F407微处理器为核心的PTP时钟应用平台,在MAC层实现了硬件时间戳获取,避免了由于协议栈软件处理延时产生的不确定性;针对PTP时钟晶振老化导致的时间同步偏差及网络延迟抖动问题,采用迭代方法优化了本地时钟频率调节算法,提高了频率校正精度。经实际测试,主从时钟偏差的RMS(root mean square)优于20 ns,提升了时钟同步精度。
基金supported by the National Natural Science Foundation of China (No.81973568)the Earmarked Fund for China Agriculture Research System (No.CARS-21)the Special Financial Project of the Ministry of Agriculture and Rural Areas (No.NFZX2024)。
文摘Eight previously undescribed lanostane triterpenoids,including five nortriterpenoids with 26carbons,ganothenoids A-E(1-5),and three lanostanoids,ganothenoids F-H(6-8),along with 24 known ones(9-32),were isolated from the fruiting bodies of Ganodrma theaecolum.The structures of the novel compounds were elucidated using comprehensive spectroscopic methods,including electronic circular dichroism(ECD)and nuclear magnetic resonance(NMR)calculations.Compounds 1-32 were assessed for their neuroprotective effects against H_(2)O_(2)-induced damage in human neuroblastoma SH-SY5Y cells,as well as their inhibitory activities against protein tyrosine phosphatase 1B(PTP1B)andα-glucosidase.Compound 4demonstrated the most potent neuroprotective activity against H_(2)O_(2)-induced oxidative stress by suppressing G_0/G_1 phase cell cycle arrest,reducing reactive oxygen species(ROS)levels,and inhibiting cell apoptosis through modulation of B-cell lymphoma 2 protein(Bcl-2)and Bcl-2 associated X-protein(Bax)protein expression.Compounds 26,12,and 28 exhibited PTP1B inhibitory activities with IC_(50)values ranging from 13.92 to 56.94μmol·L~(-1),while compound12 alone displayed significant inhibitory effects onα-glucosidase with an IC_(50)value of 43.56μmol·L~(-1).Additionally,enzyme kinetic analyses and molecular docking simulations were conducted for compounds 26 and 12 with PTP1B andα-glucosidase,respectively.
基金NIH and NIAMS Grants R21 AR081642(W.Y.),R01 AR066746(W.Y.),R01 AR080062(V.L.)and R01 AR83245(V.L.)supported by the Rhode Island Hospital Orthopaedic Foundation(W.Y.).
文摘The SH2 domain-containing protein tyrosine phosphatase 2(SHP2,also known as PTP2C),encoded by PTPN11,is ubiquitously expressed and has context-specific effects.It promotes RAS/MAPK signaling downstream of receptor tyrosine kinases,cytokine receptors,and extracellular matrix proteins,and was shown in various lineages to modulate cell survival,proliferation,differentiation,and migration.Over the past decade,PTPN11 inactivation in chondrocytes was found to cause metachondromatosis,a rare disorder characterized by multiple enchondromas and osteochondroma-like lesions.Moreover,SHP2 inhibition was found to mitigate osteoarthritis pathogenesis in mice,and abundant but incomplete evidence suggests that SHP2 is crucial for cartilage development and adult homeostasis,during which its expression and activity are tightly regulated transcriptionally and posttranslationally,and by varying sets of functional partners.Fully uncovering SHP2 actions and regulation in chondrocytes is thus fundamental to understanding the mechanisms underlying both rare and common cartilage diseases and to designing effective disease treatments.We here review current knowledge,highlight recent discoveries and controversies,and propose new research directions to answer remaining questions.
