Ultrastructural features of the myotendinous junction of the sternomastoid muscle in Wistar rats: From newborn to aging

The myotendinous junction (MTJ) is a major area for transmitting force from the skeletal muscle system and acts in joint position and stabilization. This study aimed to use transmission electron microscopy to describe the ultrastructural features of the MTJ of the sternomastoid muscle in Wistar rats from newborn to formation during adulthood and possible changes with aging. Ultrastructural features of the MTJ from the newborn group revealed pattern during development with interactions between muscle cells and extracellular matrix elements with thin folds in the sarcolemma and high cellular activity evidenced through numerous oval mitochondria groupings. The adult group had classical morphological features of the MTJ, with folds in the sarcolemma forming long projections called “finger‐like processes” and sarcoplasmic invaginations. Sarcomeres were aligned in series, showing mitochondria near the Z line in groupings between collagen fiber bundles. The old group had altered “finger‐like processes,” thickened in both levels of sarcoplasmic invaginations and in central connections with the lateral junctions. We conclude that the MTJ undergoes intense activity from newborn to its formation during adulthood. With increasing age, changes to the MTJ were observed in the shapes of the invaginations and “finger‐like processes” due to hypoactivity, potentially compromising force transmission and joint stability. Microsc. Res. Tech. 75:1292–1296, 2012. © 2012 Wiley Periodicals, Inc.     

Image mean square displacement to study the lateral mobility of Angiotensin II type 1 and Endothelin 1 type A receptors on living cells

The lateral mobility of membrane receptors provides insights into the molecular interactions of protein binding and the complex dynamic plasma membrane. The image mean square displacement (iMSD) analysis is a method used to extract qualitative and quantitative information of the protein diffusion law and infers how diffusion dynamic processes may change when the cellular environment is modified. The aim of the study was to describe the membrane diffusing properties of two G‐protein‐coupled receptors namely Angiotensin II type 1 (AT₁) and Endothelin 1 type A (ET_A) receptors and their corresponding receptor–ligand complexes in living cells using total internal reflection fluorescent microscopy and iMSD analysis. This study showed that both AT₁ and ET_A receptors displayed a mix of three modes of diffusion: free, confined, and partially confined. The confined mode was the predominant at the plasma membrane of living cells and was not affected by ligand binding. However, the local diffusivity and the confinement zone of AT₁ receptors were reduced by the binding of its antagonist losartan, and the long‐range diffusion with the local diffusivity coefficient of ET_A receptors was reduced upon exposure to its antagonist BQ123. To the best of our knowledge, this is the first study addressing the protein diffusion laws of these two receptors on living cells using total internal reflection fluorescence microscopy and iMSD.     

基于绿色制造的环保型干式切削刀具的设计研究

刀具是机械加工的重要环节,随着人类文明的发展和工业的进步,切削加工中产生的环境污染问题日益受到关注,为了贯彻环境保护政策,环保型刀具的使用将成为未来金属切削加工发展趋势之一。这里从绿色制造的角度出发对环保型干式切削刀具的材料选择、几何角度调整、结构设计等方面进行了深入的研究。     

跨超声速风洞套筒式调压阀副密封故障分析与改进

介绍了跨超声速风洞套筒式调压阀的结构,分析了副密封的故障原因,论述了副密封的改进方案及其效果。     

浅谈MAG焊和埋弧焊在箱式井架的应用

从箱式井架的结构形状和焊缝接头形式出发,针对MAG焊和埋弧焊的特点进行了论述,生产结果证明,通过两种优质、高效方法的运用,使焊接质量得到了保障,生产效率得到很大提高.