Electrophysiological characterization of rabbit distal convoluted tubule cell

The distal convoluted tubule (DCT) from rabbit kidney were perfused in vitro to study the conductive properties of the cell membranes by using electrophysiological methods. When the lumen and the bath were perfused with a biearbonate free solution buffered with HEPES, the transepithelial voltage (V _T) averaged –2.8±0.6 mV (n=20), lumen negative. The basolateral membrane voltage (V _B) averaged –77.8±1.1 mV (n=33) obtained by intracellular impalement of microelectrodes. Cable analysis performed by injecting a current from perfusion pipette revealed that the transepithelial resistance was 21.8±1.7 ·cm² and the fractional resistance of the luminal membrane was 0.78±0.03 (n=8), indicating the existence of ionic conductances in the luminal membrane. Addition of amiloride (10^–5 mol/l) to the luminal perfusate or Na⁺ removal from the lumen abolished the lumen negativeV _T and hyperpolarized the apical membrane. An increase in luminal K⁺ concentration from 5 to 50 mmol/l reduced the apical membrane potential (V _A) by 37.5±2.6 mV (n=7), whereas a reduction of Cl^– in the luminal perfusate did not changeV _A significantly (0.5±0.5 mV,n=4). Addition of Ba²⁺ to the lumen reducedV _A by 42.6±1.0 mV (n=4). When the bathing fluid was perfused with 50 mmol/l K⁺ solution, the basolateral membrane voltage (V _B) fell from –76.8±1.5 to –31.0±1.3 mV (n=18), and addition of Ba²⁺ to the bath reducedV _B by 18.3±4.8 mV (n=7). Although a reduction of Cl^– in the bathing fluid from 143 to 5 mmol/l did not cause any significant fast initial depolarization (1.8±1.7 mV,n=8), a spike like depolarization (14.0±2.5 mV,n=4) was observed, upon Cl^– reduction in the presence of Ba²⁺ in the bath. From these results, we conclude that the apical membrane of DCT has both K⁺ and Na⁺ conductances and the basolateral membrane has a K⁺ conductance and a small Cl^– conductance.     

Experimental myotonia in mammalian skeletal muscle: changes in membrane properties

Summary When myotonia is induced in rat diaphragms either by addition of 2,4-dichlorphenoxyacetate to the solution in which the excised muscle is bathed or by feeding animals on 20,25-diazocholesterol, the most significant change in membrane properties of the myotonic muscle fibres is an increase of the specific membrane resistance by a factor of 2 to 2.5. Membrane resting potential and capacitance are not altered. Like in healthy muscle, in 20,25-induced myotonic muscle the fibre membrane does not show rectifier properties ± 12 mV around the resting potential. The threshold for eliciting an action potential is unchanged but it is easier to start a burst of action potentials with a suprathreshold stimulus.This work was supported by the Deutsche Forschungsgemeinschaft.     

横向电场作用下外周神经的兴奋模型

外周神经的兴奋机理研究是以神经生理学的电缆方程为基础,方程中的激励因子只与外电场沿神经方向的纵向电场分量有关。但实验表明垂直于神经走向的横向电场也可以兴奋外周神经,因而传统电缆方程不能客观反映外周神经兴奋实际过程而需要改进。本文基于两阶段过程,建立了横向电场作用下外周神经的兴奋模型,表明了在横向电场作用下沿朗飞氏结径向的净内向电流导致了神经兴奋,从而阐述了外周神经在横向电场中的兴奋机理,改进了经典电缆方程。模型通过了离体实验验证。此改进的电缆方程可以描述任意电场激励下的外周神经兴奋。     

卫生填埋场导气沟槽间距的确定

卫生填埋场导气沟槽间距的选择，关系到填理场运行费用，填埋操作和填进的容积损失等，介绍了在保证导气效果的前提下，沟槽间距的大小的计算方法，同时讨论了影响间距的各种因素：垃圾层中最大允许压力、垃圾层的透气性能、垃圾的产气速率等。所得的结论也可用来指导已运行埴埋场的改造。     

The effect of multifilaments and monofilaments on cementless femoral revision hip components: an experimental study

Background

Cerclage wires are widely used in revision hip surgery to reattach the lid of a femoral osteotomy. The present study compared the influence of multifilaments and monofilaments on primary stability of revision hip stems with different fixation principles.

Methods

A standardized extended proximal femoral osteotomy was performed in the anterior cortex of 6 synthetic femora. We used a high-resolution measuring device to explore spatial micromovements of a diaphyseal and a metaphyseal fixating revision stem. Both of these were implanted in 3 femora. The specimens were measured again after consecutive restabilization of osteotomies with multifilaments and monofilaments. The movement graphs generated defined relative micromovements between stems and bones and the stabilizing effect of the two wire systems compared.

Findings

Both multifilaments and monofilaments effected a major reduction of relative micromovements for both fixation principles. There were no differences in relative movements between the multifilament and monofilament treatments for the diaphyseal fixating stem. Yet for the metaphyseal fixating stem a significantly better restabilization was observed with multifilaments.

Interpretation

Both multifilaments and monofilaments can support the revision hip stem in bridging the extended proximal femoral osteotomy. Yet, which wiring system should be chosen depends on the fixation principle of the revision stem. Multifilaments seem to be advantageous when used with metaphyseal fixating stems. However, the use of multifilaments with diaphyseal fixating components should be reconsidered as this might constrict the periosteal vascularity.     

穿骨道线缆结合带尾孔克氏针治疗髌骨骨折

目的:探讨应用穿骨道线缆结合带尾孔克氏针治疗髌骨骨折的临床疗效.方法:自2012年5月至2013年7月,采用穿骨道线缆结合带尾孔克氏针内固定治疗34例髌骨骨折患者,均为闭合性骨折,其中男18例,女16例;年龄26～81岁,平均(46.0±3.0)岁;横形骨折12例,粉碎性骨折22例.观察患者的手术时间、术中出血量、术后膝关节首次锻炼时间及术后并发症情况,术后根据B(o)stman髌骨骨折疗效评分标准对其功能进行评价.结果:所有患者获得随访,时间12～26个月,平均(16.0±2.0)个月.所有患者伤口甲级愈合,骨折全部愈合.手术时间(54.2±10.4) min,术中出血量(56.0±8.5)ml,术后膝关节首次锻炼时间(4.6±1.3)d.术后无感染、退针、线缆松脱,无皮肤刺激等并发症发生.根据B(o)stman髌骨骨折疗效评分标准进行评价,总分29.06±1.67,其中优33例,良1例.结论:穿骨道线缆结合带尾孔克氏针系统内固定治疗髌骨骨折,特别是横形骨折,固定牢固可靠,可早期活动膝关节,并发症少.     

330kV XLPE电缆特殊试验草案的要求

一般来说,对150 kV以上挤压式绝缘的地下电力电缆,其试验要求和试验方法系按IEC62067的推荐方法。但这个标准不包括XLPE绝缘温度高达100℃持续2小时的型式试验,它不会作预防性试验当电缆故障运行时温度达到105℃或者时间延长,也不会对微型缺陷以及在XLPE和半导电屏蔽层存在杂质的预防性检测。再者IEC62067标准也不包括一些特定的机械和电器试验,这些试验能提供一些关键性数据,以提高电缆系统设计延长寿命的信心。因此,一些公用事业单位会提出要求,根据国家标准和企业本身的标准,额外增加一些试验。在2014年,澳洲跨网（Trans Grid）公司完成设计、制造和安装一条双回路330 kV XLPE电缆线路,跨过澳洲悉尼15.5 km长的路径,并装上条件监控系统（Condition monitoring system CMS）。这个电缆系统系澳洲首次安装的主要330 kV XLPE电缆。为了给跨网公司的高压网络更可靠的要求,除了按IEC62067标准推荐的试验外,还进行了一系列的特殊试验,以便更好地了解该电缆系统的性能,特别是在高温的情况下。这些特殊的附加试验为：a）热循环电压试验（Heating Cycle Voltage Test HCVT）¬——这个试验的电缆、电缆附件和条件监控系统（CMS）作为一个整体试验,模拟现场实际的安装条件。这个HCVT组合,是在常温及事故温度之间,施加4个分别开的加热和冷却循环阶段,以模拟运行的条件,即连续施加电压2U （420 kV）,见表2.1.在试验每一阶段完成后,测量电缆的温度和局放（PD）。完成试验后,整个组合尝试进行一个升压破坏试验,以决定在加速老化过程中,通过了施加电力和热应力后,对这个系统的功能限制。b）预制铸模接头压力试验——这个试验的目的就是要测量和确定,在热循环过程中以及在最低及最高（105℃）运行温度的条件下,得出电缆绝缘与EPR橡胶模界面处的最大和最小的压应力。c)摩擦系数试验——这个试验的目的是要测量,在预定的运行温度时,得出电缆芯与波纹金属护套之间的摩擦水平。d)短路联结试验——这个试验是要验证电缆金属护套与接头金属套筒之间的连接热稳定性。上述这些试验的结果,可在预期电缆寿命过程中,通过了全部运行的条件。对确认电缆系统的设计将是十分有利的,而且可提供有价值的数据,进行条件评估和电缆系统管理,又可采用电缆蛇形敷设和预制模接头进行连接,从而大大简化现场施工敷设电缆的工作。     

电缆终端防扭器的研制

本文对电缆穿仓过程中易出现的问题进行了分析,提出了解决问题的措施,设计研制出电缆终端防扭器装置。该装置利用抱箍及螺杆将电缆终端头尾管与电缆本体在穿仓时临时连接固定,从而保护电缆终端头的搪铅处,使得电缆终端头的穿仓快速、可靠,保证施工质量。该装置的使用可提高电缆终端施工的效率与质量,具有推广价值。     

基于电力电缆屏蔽层载波技术的远程测温系统

电力电缆过热运行会造成绝缘损坏引发故障,在电缆排列密集区更有可能引起大面积火灾事故。基于电缆屏蔽层载波通信技术的远程电缆测温系统可以及时预警,避免大面积火灾事故的发生。利用远程电缆测温系统的功能、原理、通信方式以及软件运行系统,能够实时监测电缆温度,为设备维护检修提供指导依据,有效预警火灾事故。根据在西安供电局的运行情况,系统远程数据传输可靠性达到99.6%,温度误差小于±0.5℃,实现实时报警,从而满足远程电缆温度监测要求。     

在线监测系统在广州高压电缆隧道的应用

电缆状态在线监测是未来发展趋势,本文介绍了目前应用在广州高压电缆隧道内的各种在线监测手段,通过在线监测系统实现隧道环境和电缆运行状态的实时监控以及长期追踪,逐步将传统粗放的电缆运行管理模式转变为自动化监控、智能化管理的新模式。