半空间上方金属腔时域屏蔽效能的计算及分析

针对复杂半空间格林函数难以计算的问题,提出一种改进的半空间时域有限差分(FDTD)方法,实现有耗半空间上方细缝金属腔的时域屏蔽效能的高效计算和分析。首先,采用广义传播矩阵法计算半空间复反射系数,再结合傅里叶变换得到半空间时域反射回波。其次,将直接入射波和半空间反射波共同引入到FDTD计算区域,半空间的影响通过反射波体现,从而回避计算形式复杂的半空间格林函数,实现金属腔内部观察点的耦合场及时域屏蔽效能的快速计算。与传统半空间FDTD方法相比,计算方法的误差在0.5%以内,而计算效率提升52%,证明了计算方法的正确性及有效性。结果表明,由于半空间的反射效应,细缝腔体内部观察点的场强增大,时域屏蔽效能显著下降。计算方法可用于半空间背景下腔体时域屏蔽效能的快速分析,从而为电子系统电磁耦合效应的评估提供参考。

The arresting phase determines the total healing time of a locally irradiated skin wound in swine

Objective：Radiation is an important cause of delayed wound healing,and there still exist many questions regarding the patterns and mechanisms of wound healing.This study investigated the characteristics of wound healing after varying doses of local radiation and explored possible causes of the delay in healing caused by radiation.Methods：A full-thickness dorsal longitudinal skin tissue,2 cm in diameter,was excised after local irradiation on one side of the back of swine,and the other side was wounded as a control.The size of the wound area was recorded every two days after injury.Pathological changes,proliferating cell nuclear antigen（PCNA,immunohistochemistry）and apoptosis levels（TUNEL assay）were measured at different time points after wounding.Results：The course of wound healing can be divided into four phases,namely：the arresting phase,the healing priming phase,the fast healing phase,and the healed phase.Although the total wound healing time was closely correlated to the dose of irradiation（R2=0.9758）,it was more dependent on the length of the arresting phase（R2=0.9903）because once the arresting phase ended,the wound healed at a similar speed regardless of radiation doses.Pathological analysis showed that compared with the control side there were more necrotic tissues,slower epithelial crawling,as well as fewer blood vessels and cellular components in the irradiated side at the arresting phase,while other phases revealed no significant difference concerning these measurements.Immunohistochemistry showed that the irradiated wounds had significantly less PCNA-positive and more TUNEL-positive labeling of cells in the arresting phase than in other phases.Moreover,the changes were positively related to the radiation doses,but there was no obvious difference in cell proliferation or apoptosis among the healing priming phase,fast healing phase or healed phase,whether on the control side or on the irradiated side.Conclusions：After local irradiation,the length of the arresting phase determines the wound healing time.Increased apoptosis and decreased cell proliferation might be an important reason for the formation of the arresting phase.

小鼠中度颅脑创伤急性期激活腺苷A2A受体强化草酰乙酸的神经保护作用

本文旨在探讨联合应用谷氨酸清除剂草酰乙酸(oxaloacetate,OA)和腺苷A2A受体(adenosine A2A receptor,A2AR)激动剂CGS21680在中度颅脑创伤(traumatic brain injury,TBI)急性期中的神经保护作用和机制。使用C57BL/6J小鼠建立中度TBI模型,伤后急性期分别单纯使用OA、CGS21680或联合使用OA和CGS21680,伤后24 h检测神经功能评分、脑含水量、脑脊液谷氨酸浓度、脑组织IL-1β和TNF-α水平、谷氨酸草酰乙酸转氨酶(glutamate oxaloacetate aminotransferase,GOT)水平和活性及ATP浓度。结果表明,与TBI组相比,单纯使用CGS21680加重脑损伤,包括加重神经功能缺损、提高脑含水量、脑脊液谷氨酸水平和促进神经炎症;单纯使用OA可以抑制脑脊液谷氨酸水平和脑含水量的升高,并提高脑组织ATP浓度;联合使用OA和CGS21680改善了神经功能评分,降低了脑含水量、脑脊液谷氨酸浓度以及脑组织IL-1β和TNF-α的mRNA含量和蛋白水平,增加了ATP水平,且效果优于单纯使用OA组。此外,单纯使用CGS21680提高了脑组织GOT活性,早期联合使用OA和CGS21680提高了脑组织GOT的mRNA水平和活性,提示激活A2AR可提高GOT效能,促进OA代谢谷氨酸的能力,这可能是联合用药组A2AR激活不仅没有加重损伤,反而强化OA神经保护作用的机制。本研究为A2AR激动剂和OA运用于TBI临床治疗提供了新的思路。