Mechanical Load and Piezo1 Channel Regulated Myosin II Activity in Mouse Lenses

The cytoarchitecture and tensile characteristics of ocular lenses play a crucial role in maintaining their transparency and deformability, respectively, which are properties required for the light focusing function of ocular lens. Calcium-dependent myosin-II-regulated contractile characteristics and mechanosensitive ion channel activities are presumed to influence lens shape change and clarity. Here, we investigated the effects of load-induced force and the activity of Piezo channels on mouse lens myosin II activity. Expression of the Piezo1 channel was evident in the mouse lens based on immunoblot and immufluorescence analyses and with the use of a Piezo1^-tdT transgenic mouse model. Under ex vivo conditions, change in lens shape induced by the load decreased myosin light chain (MLC) phosphorylation. While the activation of Piezo1 by Yoda1 for one hour led to an increase in the levels of phosphorylated MLC, Yoda1 treatment for an extended period led to opacification in association with increased calpain activity and degradation of membrane proteins in ex vivo mouse lenses. In contrast, inhibition of Piezo1 by GsMTx4 decreased MLC phosphorylation but did not affect the lens tensile properties. This exploratory study reveals a role for the mechanical load and Piezo1 channel activity in the regulation of myosin II activity in lens, which could be relevant to lens shape change during accommodation.     

Cytopathological Outcomes of Knocking down Expression of Mitochondrial Complex II Subunits in Dictyostelium discoideum

Mitochondrial Complex II is composed of four core subunits and mutations to any of the subunits result in lowered Complex II activity. Surprisingly, although mutations in any of the subunits can yield similar clinical outcomes, there are distinct differences in the patterns of clinical disease most commonly associated with mutations in different subunits. Thus, mutations to the SdhA subunit most often result in mitochondrial disease phenotypes, whilst mutations to the other subunits SdhB-D more commonly result in tumour formation. The reason the clinical outcomes are so different is unknown. Here, we individually antisense-inhibited three of the Complex II subunits, SdhA, SdhB or SdhC, in the simple model organism Dictyostelium discoideum. Whilst SdhB and SdhC knockdown resulted in growth defects on bacterial lawns, antisense inhibition of SdhA expression resulted in a different pattern of phenotypic defects, including impairments of growth in liquid medium, enhanced intracellular proliferation of the bacterial pathogen Legionella pneumophila and phagocytosis. Knockdown of the individual subunits also produced different abnormalities in mitochondrial function with only SdhA knockdown resulting in broad mitochondrial dysfunction. Furthermore, these defects were shown to be mediated by the chronic activation of the cellular energy sensor AMP-activated protein kinase. Our results are in agreement with a role for loss of function of SdhA but not the other Complex II subunits in impairing mitochondrial oxidative phosphorylation and they suggest a role for AMP-activated protein kinase in mediating the cytopathological outcomes.     

基于Nios II的嵌入式Web服务器

21世纪计算机网络已经成为人们广泛使用的工具。通过计算机网络,人们可以进行网络控制、信息交换等。本文介绍一种基于NiosII处理器的嵌入式Web服务器的设计方法。系统在Cyclone系列1C20F400C7芯片上,采用软核处理器NiosII来配置核心处理器。NiosII核是用户可随时配置和构建的32位指令集和数据通道的嵌入式系统微处理器IP核,网络协议采用LWIP,这是一种专门针对嵌入式系统应用而设计的网络通信协议,接口芯片使用LAN9C111。本文基于NiosII的嵌入式Web服务器能够达到预期的效果,用户可以通过IE浏览器浏览存储在FLASH芯片中的网页,由于CPU本身是以软核的方式实现,其功能可根据需要进行定制,非常灵活。     

一种用于靶场多台站的时间同步电路设计

在靶场组网测试中,测试终端和多个测试分站间的时间同步直接影响测试参数准确性,为提高时间同步精度,基于SOPC技术和GPS授时相结合设计了测试分站时间同步电路。通过GPS接收机输出1PPS脉冲信号作为测试站的时间基准信号,在FPGA中设计Nios II处理器及相应的逻辑模块,由Nios II处理器通过中断信号提取当前时刻的UTC时间信息,逻辑模块实现本地时钟与GPS-1PPS脉冲信号的时间差,最终得出精确的微秒级UTC时间。该电路具有精度高、功耗低、集成度高等特点,对实现测试系统集成优化设计,提高系统的可靠性、灵活性、稳定性具有重要意义。     

Examination of the Mode II fracture behaviour of wood with a short crack in an asymmetric four-point bending test

Asymmetric four-point bending tests of agathis specimens with a short crack along the neutral axis in a tangential–longitudinal system were conducted onto analyse the failure behaviour of wood with a short crack. The nominal shear strength and Mode II critical stress intensity factors of the specimens with various crack lengths were measured, and the influence of crack length on these properties was examined. The nominal shear strength of the cracked specimens was significantly lower than the strength of a crack-free specimen, even when the crack was extremely short. This finding suggests that the fracture mechanics theory is effective for analysing the failure behaviour of wood with a very short crack in this loading condition. However, the Mode II critical stress intensity factor still depends on the crack length. When the crack length was corrected with considering the formation of fracture process zone ahead of the crack tip, the critical intensity factor could be predicted effectively as well as the nominal shear strength.     

Reduction of Cu(II) to Cu(I) in solid CsCuCl3

The solid state reaction Cu + Cu²⁺ → 2Cu⁺ in CsCuCl₃ was studied at 499 K using a cell in which the Cu(II) sample was put between two copper discs. Mass changes, thickness of the product layer and the total electrical resistance of the cell were measured as a function of time, both with and without (spontaneous) applied voltage.     

大化甲醇项目25500Nm3/h空分氩系统调试总结

介绍了大化甲醇装置空分氩系统调试经过,并进行了经验总结.     

Studies of temperature and time-dependent network formation in commercial epoxy resins using modified imidazole curing agents

Two commercial epoxy resins, MY750 and MY720, were cured over a range of cure temperatures with a series of novel curing agents based on modified imidazoles. A combination of techniques, including dynamic viscometry, proton nuclear magnetic resonance spectroscopy, differential scanning calorimetry, high performance and gel permeation chromatography, were used to analyse the reaction mixture. It appears that for a given formulation and given resin, the viscosity behaviour near gelation is different for different cure temperatures and the mechanism appears to be dependent not only on the nature of the imidazole curing agent, but also on the cure temperature. Higher temperature cure appears to lead to the formation of a less ‘homogeneous’ reaction mixture at the gel point, containing oligomeric chain lengths of higher polydispersity, whereas in the lower temperature cure, oligomers of a smaller range of chain lengths are present.     

Immature Vascular Smooth Muscle Cells in Healthy Murine Arteries and Atherosclerotic Plaques: Localization and Activity

The local development of atherosclerotic lesions may, at least partly, be associated with the specific cellular composition of atherosclerosis-prone regions. Previously, it was demonstrated that a small population of immature vascular smooth muscle cells (VSMCs) expressing both CD146 and neuron-glial antigen 2 is postnatally sustained in atherosclerosis-prone sites. We supposed that these cells may be involved in atherogenesis and can continuously respond to angiotensin II, which is an atherogenic factor. Using immunohistochemistry, flow cytometry, wound migration assay xCELLigence system, and calcium imaging, we studied the functional activities of immature VSMCs in vitro and in vivo. According to our data, these cells do not express nestin, CD105, and the leptin receptor. They are localized in atherosclerosis-prone regions, and their number increases with age, from 5.7% to 23%. Immature VSMCs do not migrate to low shear stress areas and atherosclerotic lesions. They also do not have any unique response to angiotensin II. Thus, despite the localization of immature VSMCs and the presence of the link between their number and age, our study did not support the hypothesis that immature VSMCs are directly involved in the formation of atherosclerotic lesions. Additional lineage tracing studies can clarify the fate of these cells during atherogenesis.