分类: 物理学 >> 电磁学、光学、声学、传热、经典力学和流体动力学 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2021-09-27
摘要: 磁和磁单极子是物理学中的经典问题。传统磁体通常由刚性材料组成,在回答极端问题时可能面临挑战。这里,我们首次从不同于刚性磁体的导电性流体物质出发,提出通过调控液态金属机器来产生流态化内生磁性并由此构造磁单极子。基于理论解释和概念性实验证据,我们阐明了当溶液中的镓基液态金属在电驱动下发生旋转时,其内部会形成一个内生磁场,这很好地解释了两个这样分离的金属液滴能很容易融合在一起的实验现象,原因在于二者通过各自对应的N极和S极相互吸引。此外,我们还阐明了自驱动型液态金属机器也以一种内生流态化磁体出现且具有电磁同源性;当溶液中的液态镓吞食铝时,会形成一个旋转马达和在体动态变化的电荷分布,从而在内部产生内生磁性;这就解释了运动中的液态金属马达之间经常发生反射性碰撞和吸引性融合的现象,这两种现象分别是由于马达之间N极和S极的动态调整引起的。最后,我们设想可通过这种流态化内生磁体制造磁单极子,并提出了实现这一目标的四条技术路线:1. 匹配液态金属机器的内部流场;2. 基于外电场效应与磁场的叠加效应;3. 借助磁颗粒与液态金属马达之间的复合结构;4. 化学途径,如通过原电池反应。总的来说,本文理论和提供的实验证据揭示了液态金属机器作为流体型内生磁体的机制,并指出了实现磁单极的一些有希望的途径。在不久的将来,在此基础上建立一些非传统型磁电器件和应用是可能的。
分类: 生物学 >> 生物物理学 提交时间: 2016-05-05
摘要: Natural killer (NK) cells exert a crucial role in early immune responses as a major innate effector component. However, the underlying mechanisms of NK cell development remain largely elusive. Here we show that robust autophagy appears in the stage of immature NK cells (iNKs), which is required for NK cell development. Autophagy defects result in damaged mitochondria and accumulation of reactive oxygen species (ROS) that leads to apoptosis of NK cells. Autophagy protects NK cell viability during development through removal of damaged mitochondria and intracellular ROS. Phosphorylated Forkhead box O (FoxO)1 is located to the cytoplasm of iNKs and interacts with Atg7, leading to induction of autophagy. FoxO1 deficiency or an inactive FoxO1(AAA) mutant abrogates autophagy initiation in iNKs and impairs NK cell development and viral clearance. Therefore we conclude that FoxO1-mediated autophagy is required for NK cell development and NK cell-induced innate immunity.
分类: 生物学 >> 生物物理学 提交时间: 2016-05-05
摘要: Epigenetic regulatory complexes play key roles in the modulation of transcriptional regulation underlying neural stem cell (NSC) proliferation and progeny specification. How specific cofactors guide histone demethylase LSD1/KDM1A complex to regulate distinct NSC-related gene activation and repression in cortical neurogenesis remains unclear. Here we demonstrate that Rcor2, a co-repressor of LSD1, is mainly expressed in the central nervous system (CNS) and plays a key role in epigenetic regulation of cortical development. Depletion of Rcor2 results in reduced NPC proliferation, neuron population, neocortex thickness and brain size. We find that Rcor2 directly targets Dlx2 and Shh, and represses their expressions in developing neocortex. In addition, inhibition of Shh signals rescues the neurogenesis defects caused by Rcor2 depletion both in vivo and in vitro. Hence, our findings suggest that co-repressor Rcor2 is critical for cortical development by repressing Shh signalling pathway in dorsal telencephalon.