We are grateful for the design and fabrication assistance of D. De La Cruz, for equipment borrowed from M. Zahn, and for insightful discussions with D. R. Sadoway and the talented electrochemists of his group.

1.系统设置和大会<ol><li>清洁的超声换能器，用异丙醇。 </li><li>装入手套箱。 <ol><li>负载所需的设备和材料（包括超声换能器，ePbBi，搅拌棒，和热电偶）插入手套箱，以下手套箱制造商的说明书，以减少的氧和湿气的侵入。 </li><li>在手套箱前厅保持多孔材料在真空条件下12小时进入手套箱之前。 </li></ol></li><li>调整PID控制器（仅第一次）。 <ol><li>放置固体ePbBi相同数量的插入到将在实验（840克）所使用的电池容器中。 </li><li>周围放置了电池容器内的炉中保温，如果它已不存在，然后将盖顶上的电池容器中，沿着与负极集电体和热电偶。 </li><li>使热电偶和炉功率的所有电连接， 如图 <strong&gt; URE 2B。 </li><li>发起PID控制器的自动调谐，使用150℃作为设置点。注意：该步骤的细节将有所不同，这取决于PID控制器制造商和型号。这里使用的自动调谐通过控制四个全热循环，从RT到工作温度，在一个小时的过程控制器。 <ol><li>使用箭头键来调节设定值（调整后的控制器默认显示），以150℃。 </li><li>按住循环按钮3秒，进入隐藏的循环。然后反复按循环按钮，直到控制器屏幕显示“TUNE”。使用箭头键将其更改为YES。 </li></ol></li><li>插入一个热电偶，并使用工作站来监视和记录温度。 </li><li>一旦自动调谐完成时，记录该PID控制器已自动通过控制器接口选择的比例，积分和微分参数，按吨Ø制造商的说明。 </li></ol></li></ol> 2.声速测量<ol><li>使用炉熔化足够ePbBi用于实验，至少400克注意：需要的量将随不同的设备，并ePbBi熔点为125℃。 <ol><li>如果有必要，用搅拌棒从ePbBi的顶面掠过它去除多余的氧化物。 </li><li>插入一个超声换能器成音速测定装置，并拧紧挤压连接，以防止泄漏，然后插入一个热电偶，并使用工作站来监视和记录温度。 </li></ol></li><li>熔融金属转移到声速测量装置。 <ol><li>放置声速测量装置在炉基和离开那里进行2分钟，以逐渐增加的温度，并避免热冲击。 </li><li>准备一个安全转移通过从区域移除热量敏感的设备或材料。 </li><li>添加小点熔融金属在一个时间ounts，因为热冲击会损坏超声换能器。添加ePbBi直到探头表面和微米头都完全淹没。 </li><li>等到至少5分钟温度保持稳定在1℃以内开始测量之前，由于声音的速度依赖于温度。 </li></ol></li><li>测量的超声回波在两个位置。 <ol><li>测微头设定为任意的，但已知的位置。记录超声回波测量，下面由仪器制造商提供的说明。 </li><li>使用千分表，通过公知的距离移动微米小费。记录超声回波测量。 </li></ol></li><li>从声音速度测量装置中取出的熔融金属并将其存储在一个热耐受容器。 </li><li>要确定的声音的速度，情节回波振幅的回波时间为每两次测量的功能。通过拟合高斯曲线找到回声到每一回波峰值，如在图 茜 4。通过将位移距离由回波峰值时间差计算声速。 </li></ol> 3.超声速度测量<ol><li>熔体足够ePbBi做实验（840克），如果有必要去除多余的氧化物。注：为获得最佳效果，请使用ePbBi被用来调整的PID控制器相同的数量。 <ol><li>插入一个超声换能器到电池容器中，并拧紧挤压连接，以防止泄漏，确保该炉基是水平的。 </li></ol></li><li>熔融金属转移到电池容器。 <ol><li>将电池壳上炉底座，让它有5分钟逐渐增加温度，避免热冲击。准备一个安全转移通过从区域移除热量敏感的设备或材料。 </li><li>添加少量的熔融金属的时间，因为热冲击会损坏微升trasound传感器。 </li><li>等到温度达到150℃开始测量前，因为声速取决于温度。 </li></ol></li><li>完成组装该装置。 <ol><li>周围放置了电池容器内的炉中保温，如果它已不存在。放置在盖顶上的电池容器中，沿着与负极集电体和热电偶。要确保所有的精确和可重复定位;轴环非常适用于此。 </li><li>使这两个功率和信号的所有电连接， 如图 茜 2B。用欧姆表确认没有意外的电路路径存在， 即检查负电流收集器和所有信号引线之间的电阻至少为1MΩ。 </li></ol></li><li>开始进行测量。 <ol><li>开始记录和监控温度，加热功率，电池电压和电池电流。注：在这里，工作站运行定制的LabVIEW代码是用来记录所有测量，与相应的时间戳。 </li><li>调整超声仪器设置是必要的。 <ol><li>一定要设置声音的速度，使用适当的温度，根据公认的模型19。为ePbBi在如下使用150℃，速度设置为1760米/秒。 </li><li>调整脉冲重复频率，使得回声深度紧密间隔（通常为0.25毫米）。 </li><li>调整使得从远处血管壁的强回声出现在最后几门的门数;它提供了一个有用的完整性检查进行故障排除信号强度问题。 </li><li>使用由制造商提供的说明，将仪器设置为硬件触发。 </li></ol></li><li>通过启动从工作站触发开始与超声仪器记​​录和监视速度。每秒记录四幅速度剖面30分钟。 </li></ol></li><li>设置为5 A的电池电流，等待5分钟的流量稳定下来，然后30分钟录制每秒4的速度分布。 </li><li> 10 A，15 A，20 A，25 A，30 A.重复步骤3.5 注意：许多其它实验方案也是可能的，包括温度变化和在当前平滑变化。气氛在低氧气和水分可以用几个小时以上良好的信号质量的实验。 </li><li>一旦试验完成后，停止记录数据并关闭炉。断开电气连接和取下炉盖。从电池容器中取出熔融金属，利用该填充的容器时被用于安全传输的相同步骤。存储熔融ePbBi在热耐受容器。添加额外的氩气的手套箱;其压力将下降，因为它的大气冷却。 </li></ol>

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The authors have nothing to disclose.

超声技术可以在数百或数千的位置在一个透明的或不透明的液体，每秒钟多次产生的速度测量。施加到液态金属电极，超声技术遇到高温，化学活性，和导电性的挑战。该方法克服这些挑战，并测量流中活性液体金属电极已被描述。首先，将电极材料受到相同的物理的高温液态金属电池的电极（550℃），但操作在低得多的温度（150℃），简化了与温度有关的挑战。一个定制的炉和调整控制系统用?...

液态金属电池是一种很有前途的技术，为全球范围内对电网1提供大规模储能。这些电池提供高能量密度，功率密度高，循环寿命长，成本低，可理想用于电网规模储能3。引入液态金属电池能源网将使调峰，提高电网的稳定性，并使更广泛地使用间歇性可再生能源如太阳能，风能，和潮汐发电。液态金属电池组成的熔盐电解质隔开两液体金属电极，如在现有工作1中更详细地描述。虽然金属和电解质许多不同的组合会导致工作液体金属电池，工作原理保持相同。所述金属被选择成使得它是能量上有利的为他们形成合金;因此，合金化放电的电池，和去合金收费吧。该SA选择所述层，使得它允许金属离子在两个电极之间通过，但中性物种的块传输，从而提供了系统的电化学控制。 这项工作将通过量化和控制大众交通的影响推动液态金属电池技术。这里介绍的方法是由液态金属电池由Sadoway 等人开发的电化学方法知情1-4以及在阿贡国家实验室的前面5,6液态金属电池的工作，以及更广泛的社会电化学的工作（巴德和福克纳7提供了许多相关的参考资料）。这里介绍的方法也建立在以前的流体动力学研究。超声测速技术的开发和第一次在水中使用8,9和已经被应用到液态金属镓，包括10,11，12,13钠，14汞，铅，铋15，铜锡15 &lt;/ SUP&gt;，和铅锂16，等等。埃克特等，提供测速的有用审查液态金属17。 类似于在这里18中的那些最近使用的工作方法表明，电池的电流可以增强集体运输液态金属电极。因为质量传递中的正电极是负责液态金属电池和放电的限速步骤，混合因此允许更快的充电和放电比其他可能的。此外混合防止了电极，可形成固体的限制电池的循环寿命局部不均匀性。在正在进行的工作，我们继续研究在液态金属电池，它产生由于热和电磁力的正极流体流动的作用。热梯度开车经过浮力对流和电池电流通过诱导面糊的磁场相互作用带动流量Ÿ电流自己。在使用以下描述的方法的实验中，我们观察到流动雷诺数50 &lt;重新&lt;200，从电极深度和根均方速度计算出。一个彻底的实验表征正在进行和将使用产生的数据集建立预测型号的电池。此论文的重点是对实验设计和所需的，以产生这样的数据的程序。超声测速提供大量的测量，和实验条件，必须以在液态金属成功使用超声波来仔细控制。高温，化学活性，和电导率都必须小心管理。 首先，液态金属电池在高温下工作不一定，因为金属和分隔它们必须是熔融盐。一个有前途的材料的选择，它使用锂作为负极，铅锑作为正电子角处接上和锂盐作为电解质的共晶混合物，需要大约550℃的温度。在如此高的温度下测量的不透明流体的流动是相当困难的。高温超声换能器，该分离的微妙电声部件从测试流体的声波导，已经证明15和商业化。然而，因为换能器具有插入损耗邻近40分贝的，并且因为在这种温度下工作的一般困难，替代系统已被选定为初始研究：一个液态金属电池也可以使用钠作为负极，共晶制成44％铅56％铋（以下ePbBi）作为正电极，和钠盐（10％的碘化钠和38％的氢氧化钠，52％钠酰胺）作为电解液的三共晶混合物。这种电池是完全熔化高于127°C，使得它更适合于实验室研究。因为它是由三个液体层是通过密度分离，它受相同的物理和其他液态金属电池。而且它是与现成超声换能器，这是在额定至230℃兼容，涉及无波导损失，成本比高温传感器少得多。这些实验通常发生在150℃。在该温度下，ePbBi的粘度ν= 2.79×10 -7平方米 /秒，热扩散率κ= 6.15×10 -6米2 /秒，和磁扩散η=0.8591米2 /秒，使得其普朗特数是PR =ν/κ= 4.53×10 -2及其磁普朗特数为PM =ν/η= 3.24×10 -7。 虽然这种低温液态金属电池化学物质，使流动的研究更容易比他们将在炎热的电池，温度仍然必须谨慎管理。作为精致的电声器件，超声换能器是susceptiblE按热冲击损坏，因此必须逐渐加热。高品质的超声测量也需要仔细调节温度。超声测速的工作方式类似声纳， 如图1：换能器发出蜂鸣声（在此，频率为8兆赫），然后监听回波。通过测量的回波的飞行时间，以呼应体的距离可以被计算，并且通过测量的回波的多普勒频移，身体的速度的一个部件也可以计算出来。在水，示踪粒子必须被添加到产生的回声，但没有示踪粒子需要在液态金属，即不理解详细但通常归因于小的金属氧化物粒子的存在的事实。每次测量的平均值在询问卷中的所有示踪粒子;在这项工作中，其最小直径为2毫米，在距离30mm处的探针。虽然氧化可能最终限制的实验的持续时间，使用第下面描述ë方法，我们不断进行的测量，只要8小时。 计算任一距离或速度需要知道声音的测试流体的速度，且将该速度随温度而变化。此处所描述的工作着重于流在ePbBi负极，其中，声音的速度是1766米/秒，在150℃，1765米/秒，在160℃，1767米/秒，在140℃下19。因此温度控制不当会在超声测量引入系统误差。的装置被构造成测量声音在ePbBi速度，查找与发表和接受核能机构19（见下文）相一致的值。最后，由于热对流是流动在液体金属电池的主要推动力，两者的平均温度和ePbBi电极的顶部和底部之间的温度差直接影响观测。对于一致的结果，精确热控制是必不可少的。 因此，温度是至少有三个K型热电偶连续测量，记录他们的测量电子与基于计算机的捕获装置和一个自定义编写的LabView程序。该方案还控制提供电池电流，通过USB连接电源;记录该电池的电流和电压;并发送触发脉冲的超声仪器，使得它的数据可以与其他测量来同步。一种系统，图中示出在图2中，加热是由一个定制炉（也示于图2），它包含两个500W的工业加热元件供电切换由比例-积分-微分中继（PID），提供控制器。支持电池单元的基板是由固体铝;因为它的热导率是一个数量级高于不锈钢届的热导率鳗鱼电池容器，它包含19 ePbBi，炉底的温度大致均匀。此外铝基兼作电电流通过电极的路径。其电导率也幅度比不锈钢或ePbBi高出一个数量级，所以在炉底板的电压也大致均匀。绝缘腿从替补分开底座顶部下方，防止烫伤和短裤。电池容器的侧面被绝缘的二氧化硅陶瓷隔热，切向紧密贴合在容器但留有余地接入小区的超声端口。最后，一​​个聚四氟乙烯（PTFE）盖绝缘细胞从上方并保持该负集电体和热电偶到位。虽然市售加热板能够达到所需的这些实验的温度下，我们的定制炉保持温度与幅值较小的变化，一个的顺序ND也可以让我们直接测量热功率。 除了与温度相关的挑战，存在与化学活性相关的挑战。在150℃，一个ePbBi正极与许多常见的材料化学相容。钠负电极，然而，侵蚀许多材料，容易氧化，并且具有防潮剧烈的化学反应。锂负极也是积极的，尤其是因为锂基液态金属电池通常在运行温度高得多。虽然这些较高温度系统是这项工作的范围之外，许多用于管理化学活性同样的措施在这里用作这些系统。此处描述的所有实验发生在含有氧气或湿气的仅微量充满氩气的手套箱中。电池容器由合金制成的304不锈钢，其腐蚀最小甚至与锂在550℃。热电偶和负电流集电极也由不锈钢制成。该容器的几何形状被选择以匹配用于液态金属电池电化学测试容器，以尽可能接近建模为可能正在商业化的系统。容器中， 如图2所示，是圆柱形的，具有一个88.9毫米内径和67毫米深度。所有的血管壁6.4毫米厚。该容器不同于那些用于早期的实验，但是，在于它具有一个超声端口。端口穿过侧壁沿着所述圆柱体的水平直径，并且该端口的中心为6.6毫米以上的容器地板。端口是8毫米直径以容纳8mm的超声换能器，和密封件围绕与型模的换能器。在这些实验中，液体金属电极仅仅是足够深，以覆盖超声波换能器，通常13毫米。 为了实现强大的超声波信号，一个需要良好的声学传输之间的超声换能器和流体其探针（ePbBi）。发送最大声功率时换能器的材料的声阻抗和测试流体是相同的;当阻抗不同，信号受到影响。放置在与清洁ePbBi直接接触的超声换能器（如成为可能由上述的端口）提供了充足的信号，通常在一个小时的时间。金属氧化物，然而，有非常不同的阻抗，并且还可以通过改变表面张力干扰润湿。如果ePbBi实质上氧化，超声信号降解并很快消失。再次，在惰性气氛是至关重要的。如果氧气痕量引起一些氧化尽管如此，金属氧化物的表面转印ePbBi到电池容器之前被脱脂。 最后，由于电流的情况下的这些实验提出了挑战。虽然电流是我们的中央科学和技术间美国东部时间，他们有足够的（30 A）大造成损害，如果不正确地路由。接地热电偶确保有害的电流不通过数据获取设备或支持它的计算机，因为接地热电偶具有从保护护套要么信号线没有内部电连接。同样有必要使用不接地超声换能器（信号处理中的SA，TR0805LTH），以防止杂散电流而损坏有价值超声仪（信号处理中的SA，DOP 3010）。如前所述，在炉的底座用来传导电流，并且还必须从它的周围环境电隔离。 在ePbBi电极，电流引起的欧姆加热，有可能破坏的温度。因此，自动热控制系统必须能适应变化的热输入。 图3显示了如何ePbBi电极的温度变化作为CUR租金流经它，以及如何将PID控制器调节来补偿。保持稳定的温度有大的电流（50 A = 800毫安/平方厘米）将需要额外的冷却，但在较低的电流更现实的工业应用中的液体金属电池（典型地17 A =275毫安/厘米1），该控制器能够以补偿的欧姆加热并保持温度变化至2℃。

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>K Type Thermocouple Probe</td>
			<td>McMaster-Carr</td>
			<td>3856K83</td>
			<td><a href="http://www.mcmaster.com/">http://www.mcmaster.com/</a></td>
		</tr>
		<tr>
			<td>Red Lion PID Controller</td>
			<td>Red Lion</td>
			<td>P1610000</td>
			<td>http://store.redlion.net/store/p16.html</td>
		</tr>
		<tr>
			<td>Measurement Computing Data Acquisition Device</td>
			<td>Measurement Computing Corporation</td>
			<td>USB-2408</td>
			<td>http://www.mccdaq.com/index.aspx</td>
		</tr>
		<tr>
			<td>Power Supply</td>
			<td>TDK-Lambda</td>
			<td>GEN 8-90-USB-U</td>
			<td>http://us.tdk-lambda.com/hp/</td>
		</tr>
		<tr>
			<td>Ultrasound Instrument</td>
			<td>Signal Processing SA</td>
			<td>DOP3010</td>
			<td>http://www.signal-processing.com/index.html</td>
		</tr>
		<tr>
			<td>Ultrasound Transducer</td>
			<td>Signal Processing SA</td>
			<td>TR0805LTH</td>
			<td>http://www.signal-processing.com/index.html</td>
		</tr>
		<tr>
			<td>Bismuth-Lead Eutectic</td>
			<td>VWR</td>
			<td>AA40949-P2</td>
			<td>https://us.vwr.com/</td>
		</tr>
	</tbody>
</table>

ultrasound velocity measurement in a liquid metal electrode

越来越多的电化学技术依赖于流体流​​动，并经常流体是不透明的。测量的不透明流体的流动本身就比测量的透明流体的流动较困难，因为光学方法是不适用的。超声可用于测量不透明流体，不仅在孤立点的速度，但在沿行排列，具有良好的时间分辨率几百点或数千。当施加到液态金属电极，超声波测速涉及额外的挑战：高温，化学活性，和导电性。在这里，我们描述实验装置和克服这些挑战，并允许流动的测量在液体金属电极，因为它传导电流，在操作温度的方法。温度是用一个比例 - 积分 - 微分（PID）控制器，功率的定制炉在±2℃调节。化学活性的男人老化通过仔细选择容器材料和包封的实验配置在充满氩气的手套箱中。最后，非预期的电路径被小心防止。自动化系统记录控制设置和实验测量，使用硬件触发信号同步设备。此装置和这些方法可产生测量是不可能与其它技术，并允许优化和电化学技术，如液态金属电池的控制。

用于测量的声音的速度（在上面详细描述的）的方法改编自用于信号处理的SA的方法。原则上，声音的速度可以很容易地通过测量的回波的飞行时间从一个壁在已知范围内获得。但精确测量探头表面的有效位置是困难的，所以不是一个可以测量的飞行时间的两倍，用千分尺由测量之间的已知距离来置换壁。该位移距离，并在飞行测量的时间差，以及产生的声音的速度。用于测量在这些实验中的声?...

Watch this Scientific Journal Video about Ultrasound Velocity Measurement in a Liquid Metal Electrode at JoVE.com

Ultrasound Velocity Measurement in a Liquid Metal Electrode

Ultrasound velocimetry is used to study mixing by fluid flow in liquid metal electrodes. The focus of this manuscript is to illustrate the methods used for making precise, spatially-resolved ultrasound measurements while limiting oxidation and controlling and monitoring temperature, applied current, and the heater power being supplied.

超声速度测量的液态金属电极

A growing number of electrochemical technologies depend on fluid flow, and often that fluid is opaque. Measuring the flow of an opaque fluid is inherently ...

ultrasound-velocity-measurement-in-a-liquid-metal-electrode

Research

Education

JoVE Journal

JoVE Core

Physics

Engineering

Unit 1

Sound

SCIENTISTS IN ACTION

11.6K 次观看.  University of Rochester. Ultrasound velocimetry is used to study mixing by fluid flow in liquid metal electrodes. The focus of this manuscript is to illustrate the methods used for making precise, spatially-resolved ultrasound measurements while limiting oxidation and controlling and monitoring temperature, applied current, and the heater power being supplied.

视频: Ultrasound Velocity Measurement in a Liquid Metal Electrode

Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM, other properties such as local electronic states, ion diffusion coefficient and surface potential can also be investigated17-22. In this work, electrochemical measurements, Raman spectroscopy, and SPM were used in conjunction with a novel test electrode platform that consists of a Ni mesh electrode embedded in an yttria-stabilized zirconia (YSZ) electrolyte. Cell performance testing and impedance spectroscopy under fuel containing H2S was characterized, and Raman mapping was used to further elucidate the nature of sulfur poisoning. In situ Raman monitoring was used to investigate coking behavior. Finally, atomic force microscopy (AFM) and electrostatic force microscopy (EFM) were used to further visualize carbon deposition on the nanoscale. From this research, we desire to produce a more complete picture of the SOFC anode.

We present a unique platform for characterizing electrode surfaces in solid oxide fuel cells (SOFCs) that allows simultaneous performance of multiple characterization techniques (e.g. in situ Raman spectroscopy and scanning probe microscopy alongside electrochemical measurements). Complementary information from these analyses may help to advance toward a more profound understanding of electrode reaction and degradation mechanisms, providing insights into rational design of better materials for SOFCs.

在固体氧化物燃料电池电极表面的探测和测绘

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen ...

科研

工程学

Experimental Measurement of Settling Velocity of Spherical Particles in Unconfined and Confined Surfactant-based Shear Thinning Viscoelastic Fluids

An experimental study is performed to measure the terminal settling velocities of spherical particles in surfactant based shear thinning viscoelastic (VES) fluids. The measurements are made for particles settling in unbounded fluids&#160;and fluids between parallel walls. VES fluids over a wide range of rheological properties are prepared and rheologically characterized. The rheological characterization involves steady shear-viscosity and dynamic oscillatory-shear measurements to quantify the viscous and elastic properties respectively. The settling velocities under unbounded conditions are measured in beakers having diameters at least 25x the diameter of particles. For measuring settling velocities between parallel walls, two experimental cells with different wall spacing are constructed. Spherical particles of varying sizes are gently dropped in the fluids and allowed to settle. The process is recorded with a high resolution video camera and the trajectory of the particle is recorded using image analysis software. Terminal settling velocities are calculated from the data.
The impact of elasticity on settling velocity in unbounded fluids is quantified by comparing the experimental settling velocity to the settling velocity calculated by the inelastic drag predictions of Renaud et al.1&#160;Results show that elasticity of fluids can increase or decrease the settling velocity. The magnitude of reduction/increase is a function of the rheological properties of the fluids and properties of particles. Confining walls are observed to cause a retardation effect on settling and the retardation is measured in terms of wall factors.

This paper demonstrates the experimental procedure to measure terminal settling velocities of spherical particles in surfactant-based shear thinning viscoelastic fluids. Fluids over a wide range of rheological properties are prepared and settling velocities are measured for a range of particle sizes in unbounded fluids and fluids between parallel walls.

无约束和封闭表面活性剂中球形粒子沉降速度的实验测量 剪切变薄粘性流体

An experimental study is performed to measure the terminal settling velocities of spherical particles in surfactant based shear thinning viscoelastic ...

Development of a 3D Graphene Electrode Dielectrophoretic Device

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The protocol details the procedures to construct a versatile, reusable, multiple layer, laminated dielectrophoresis chamber. Specifically, six layers of 50 &#181;m x&#160;0.7 cm x&#160;2 cm graphene paper and five layers of double sided tape were alternately stacked together, then clamped to a glass slide. Then a 700 &#956;m diameter micro-well was drilled through the laminated structure using a computer-controlled micro drilling machine. Insulating properties of the tape layer between adjacent graphene layers were assured by resistance tests. Silver conductive epoxy connected alternate layers of graphene paper and formed stable connections between the graphene paper and external copper wire electrodes. The finished device was then clamped and sealed to a glass slide. The electric field gradient was modeled within the multi-layer device. Dielectrophoretic behaviors of 6 &#956;m polystyrene beads were demonstrated in the 1 mm deep micro-well, with medium conductivities ranging from 0.0001 S/m to 1.3 S/m, and applied signal frequencies from 100 Hz to 10 MHz. Negative dielectrophoretic responses were observed in three dimensions over most of the conductivity-frequency space and cross-over frequency values are consistent with previously reported literature values. The device did not prevent AC electroosmosis and electrothermal flows, which occurred in the low and high frequency regions, respectively. The graphene paper utilized in this device is versatile and could subsequently function as a biosensor after dielectrophoretic characterizations are complete.

A microdevice with high throughput potential is used to demonstrate three-dimensional (3D) dielectrophoresis (DEP) with novel materials. Graphene nanoplatelet paper and double sided tape were alternately stacked; a 700 &#956;m micro-well was drilled transverse to the layers. DEP behavior of polystyrene beads was demonstrated in the micro-well.

三维石墨电极介电泳装置的研制

The design and fabrication of a novel 3D electrode microdevice using 50 &#181;m thick graphene paper and 100 &#181;m double sided tape is described. The ...

Non-aqueous Electrode Processing and Construction of Lithium-ion Coin Cells

Research into new and improved materials to be utilized in lithium-ion batteries (LIB) necessitates an experimental counterpart to any computational analysis. Testing of lithium-ion batteries in an academic setting has taken on several forms, but at the most basic level lies the coin cell construction. In traditional LIB electrode preparation, a multi-phase slurry composed of active material, binder, and conductive additive is cast out onto a substrate. An electrode disc can then be punched from the dried sheet and used in the construction of a coin cell for electrochemical evaluation. Utilization of the potential of the active material in a battery is critically dependent on the microstructure of the electrode, as an appropriate distribution of the primary components are crucial to ensuring optimal electrical conductivity, porosity, and tortuosity, such that electrochemical and transport interaction is optimized. Processing steps ranging from the combination of dry powder, wet mixing, and drying can all critically affect multi-phase interactions that influence the microstructure formation. Electrochemical probing necessitates the construction of electrodes and coin cells with the utmost care and precision. This paper aims at providing a step-by-step guide of non-aqueous electrode processing and coin cell construction for lithium-ion batteries within an academic setting and with emphasis on deciphering the influence of drying and calendaring.

Non-aqueous electrode processing is central to the construction of coin cells and the evaluation of new electrode chemistries for lithium-ion batteries. A step-by-step guide to the basic practices needed as an electrochemical engineer working with batteries in an academic experimental setting is furnished.

锂离子纽扣电池的非水电极加工和施工

Research into new and improved materials to be utilized in lithium-ion batteries (LIB) necessitates an experimental counterpart to any computational ...

Preparation of Liquid-exfoliated Transition Metal Dichalcogenide Nanosheets with Controlled Size and Thickness: A State of the Art Protocol

We summarize recent advances in the production of liquid-exfoliated transition metal dichalcogenide (TMD) nanosheets with controlled size and thickness. Layered crystals of molybdenum disulphide (MoS2) and tungsten disulphide (WS2) are exfoliated in aqueous surfactant solution by sonication. This yields highly polydisperse mixtures containing nanosheets with broad size and thickness distributions. However, for most purposes, specific sizes (in terms of both lateral dimension and thickness) are required. For example, large and thin nanosheets are desired for (opto) electronic applications, while laterally small nanosheets are interesting for catalytic applications. Therefore, post-exfoliation size selection is an important step that we address here. We provide a detailed protocol on the efficient size selection in large quantities by liquid cascade centrifugation and the size and thickness quantification by statistical microscopic analysis (atomic force microscopy and transmission electron microscopy). The comparison of MoS2 and WS2 shows that both materials are size-selected in a similar way by the same procedure. Importantly, the dispersions of size-selected nanosheets show systematic changes in their optical extinction spectra with size due to edge and confinement effects. We show how these optical changes are related quantitatively to the nanosheets dimensions and describe how mean nanosheets length and layer number can be extracted reliably from the extinction spectra. The exfoliation and size selection protocol can be applied to a broad range of layered crystals as we have previously demonstrated for graphene, gallium sulphide (GaS) and black phosphorus.

A protocol for the liquid exfoliation of layered materials to nanosheets, their size selection and size measurement by microscopic and spectroscopic techniques is presented.

与尺寸可控液体剥离的过渡金属二硫属化物纳米片和厚度的制备：艺术议定书的国家

We summarize recent advances in the production of liquid-exfoliated transition metal dichalcogenide (TMD) nanosheets with controlled size and thickness. ...

Optical Trap Loading of Dielectric Microparticles In Air

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly scattered dielectric microparticles adhered to a glass substrate are momentarily detached using ultrasonic vibrations generated by a piezoelectric transducer (PZT). Then, the optical beam focused on a selected particle lifts it up to the optical trap while the vibrationally excited microparticles fall back to the substrate. A particle may be trapped at the nominal focus of the trapping beam or at a position above the focus (referred to here as the levitation position) where gravity provides the restoring force. After the measurement, the trapped particle can be placed at a desired position on the substrate in a controlled manner. 
In this protocol, an experimental procedure for selective optical trap loading in air is outlined. First, the experimental setup is briefly introduced. Second, the design and fabrication of a PZT holder and a sample enclosure are illustrated in detail. The optical trap loading of a selected microparticle is then demonstrated with step-by-step instructions including sample preparation, launching into the trap, and use of electrostatic force to excite particle motion in the trap and measure charge. Finally, we present recorded particle trajectories of Brownian and ballistic motions of a trapped microparticle in air. These trajectories can be used to measure stiffness or to verify optical alignment through time domain and frequency domain analysis. Selective trap loading enables optical tweezers to track a particle and its changes over repeated trap loadings in a reversible manner, thereby enabling studies of particle-surface interaction.

A protocol for launching and stably trapping selected dielectric microparticles in air is presented.

介电微粒的光阱装载在空气中

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly ...

Measurement of Quantum Interference in a Silicon Ring Resonator Photon Source

Silicon photonic chips have the potential to realize complex integrated quantum information processing circuits, including photon sources, qubit manipulation, and integrated single-photon detectors. Here, we present the key aspects of preparing and testing a silicon photonic quantum chip with an integrated photon source and two-photon interferometer. The most important aspect of an integrated quantum circuit is minimizing loss so that all of the generated photons are detected with the highest possible fidelity. Here, we describe how to perform low-loss edge coupling by using an ultra-high numerical aperture fiber to closely match the mode of the silicon waveguides. By using an optimized fusion splicing recipe, the UHNA fiber is seamlessly interfaced with a standard single-mode fiber. This low-loss coupling allows the measurement of high-fidelity photon production in an integrated silicon ring resonator and the subsequent two-photon interference of the produced photons in a closely integrated Mach-Zehnder interferometer. This paper describes the essential procedures for the preparation and characterization of high-performance and scalable silicon quantum photonic circuits.

Silicon photonic chips have the potential to realize complex integrated quantum systems. Presented here is a method for preparing and testing a silicon photonic chip for quantum measurements.

量子干涉效应在硅谐振环光子源测量

Silicon photonic chips have the potential to realize complex integrated quantum information processing circuits, including photon sources, qubit ...

Standardized Method for Measuring Collection Efficiency from Wipe-sampling of Trace Explosives

One of the limiting steps to detecting traces of explosives at screening venues is effective collection of the sample. Wipe-sampling is the most common procedure for collecting traces of explosives, and standardized measurements of collection efficiency are needed to evaluate and optimize sampling protocols. The approach described here is designed to provide this measurement infrastructure, and controls most of the factors known to be relevant to wipe-sampling. Three critical factors (the applied force, travel distance, and travel speed) are controlled using an automated device. Test surfaces are chosen based on similarity to the screening environment, and the wipes can be made from any material considered for use in wipe-sampling. Particle samples of the explosive 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) are applied in a fixed location on the surface using a dry-transfer technique. The particle samples, recently developed to simulate residues made after handling explosives, are produced by inkjet printing of RDX solutions onto polytetrafluoroethylene (PTFE) substrates. Collection efficiency is measured by extracting collected explosive from the wipe, and then related to critical sampling factors and the selection of wipe material and test surface. These measurements are meant to guide the development of sampling protocols at screening venues, where speed and throughput are primary considerations.

Optimized sampling protocols and the development of new wipe materials can be facilitated by standardized measurements of collection efficiency from wipe-sampling. Our approach for sampling trace explosives uses an automated device to control speed, force, and distance during wipe-sampling followed by extraction of collected explosives.

从微量炸药的擦拭取样测量收集效率的标准化方法

One of the limiting steps to detecting traces of explosives at screening venues is effective collection of the sample. Wipe-sampling is the most common ...

Three-electrode Coin Cell Preparation and Electrodeposition Analytics for Lithium-ion Batteries

As lithium-ion batteries find use in high energy and power applications, such as in electric and hybrid-electric vehicles, monitoring the degradation and subsequent safety issues becomes increasingly important. In a Li-ion cell setup, the voltage measurement across the positive and negative terminals inherently includes the effect of the cathode and anode which are coupled and sum to the total cell performance. Accordingly, the ability to monitor the degradation aspects associated with a specific electrode is extremely difficult because the electrodes are fundamentally coupled. A three-electrode setup can overcome this problem. By introducing a third (reference) electrode, the influence of each electrode can be decoupled, and the electrochemical properties can be measured independently. The reference electrode (RE) must have a stable potential that can then be calibrated against a known reference, for example, lithium metal. The three-electrode cell can be used to run electrochemical tests such as cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). Three-electrode cell EIS measurements can elucidate the contribution of individual electrode impedance to the full cell. In addition, monitoring the anode potential allows the detection of electrodeposition due to lithium plating, which can cause safety concerns. This is especially important for the fast charging of Li-ion batteries in electric vehicles. In order to monitor and characterize the safety and degradation aspects of an electrochemical cell, a three-electrode setup can prove invaluable. This paper aims to provide a guide to constructing a three-electrode coin cell setup using the 2032-coin cell architecture, which is easy to produce, reliable, and cost-effective.

Three-electrode cells are useful in studying the electrochemistry of lithium-ion batteries. Such an electrochemical setup allows the phenomena associated with the cathode and anode to be decoupled and examined independently. Here, we present a guide for construction and use of a three-electrode coin cell with emphasis on lithium plating analytics.

锂离子电池三电极硬币电池制备及电沉积分析

As lithium-ion batteries find use in high energy and power applications, such as in electric and hybrid-electric vehicles, monitoring the degradation and ...

Method Development for Contactless Resonant Cavity Dielectric Spectroscopic Studies of Cellulosic Paper

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of data that can be obtained from an individual sample and renders it difficult to produce statistically relevant data for unique and rare materials. Resonant cavity dielectric spectroscopy is a non-destructive, contactless technique which can simultaneously interrogate both sides of a sheeted material and provide measurements which are suitable for statistical interpretations. This offers analysts the ability to quickly discriminate between sheeted materials based on composition and storage history. In this methodology article, we demonstrate how contactless resonant cavity dielectric spectroscopy may be used to differentiate between paper analytes of varying fiber species compositions, to determine the relative age of the paper, and to detect and quantify the amount of post-consumer waste (PCW) recycled fiber content in manufactured office paper.

A protocol for the non-destructive analysis of the fiber content and relative age of paper.

纤维素纸非接触式共振腔电谱研究的方法研究

The current analytical techniques for characterizing printing and graphic arts substrates are largely ex situ and destructive. This limits the amount of ...