这项工作是由ICT R＆MSIP / IITP，大韩民国（:B0132-15-1001，下一步成像系统的开发批准号）的D程序的支持。

1.设计一个平面FMMD测量头<ol><li>选择的测量头线圈方案。根据图1选择的结构，由两个拾取线圈上面和两个样品下面的（ - ，+，+， - ）序列，与样品坐在两个（+），线圈之间的中心。该标志表示绕组， 即顺时针方向和方向，（+），（ - ）为逆时针方向。由此，拾取线圈的灵敏度变整个样品厚度几乎是均匀的。 <ol><li>放置励磁线圈，使得在拾取线圈直接感应信号，以防止前置放大器的饱和，实现到样品最大灵敏度抵消。满足这些基本的设计规则其它构造可设计。 </li></ol></li><li>指定最大样品厚度。在这里，使用2毫米。 <ol><li>选择拾取线圈的直径和长度类似于最大样本thickness。这里，为2毫米的内径被选择，这将产生3.7毫米为1.7mm绕组的高度的平均直径。线圈宽度为4mm。 </li><li>选择导线直径和拾取线圈这样的绕组数，所有拾取线圈的总阻抗大致匹配的前置放大器的输入阻抗。这个条件强加的检测次数的限制。在运算放大器与1100Ω最佳的输入阻抗，这样所有四个线圈拾音器有0.08毫米直径600绕组。漆包线，得到95.3Ω的总欧姆串联电阻和1.9毫亨，这给919Ω阻抗的总电感。 </li></ol></li><li>制备高频激磁线圈17，使得在该示例的位置的磁场理想地达约0.5 mT的。例如，如果线圈的内径为3.8毫米，宽度为8.5毫米，风粒径约0.1mmφ476绕组瓦特<html>愤怒。在这里，0.4 mT的一场场在f 1 = 76550赫兹达到了。 </li><li>准备低频激磁线圈17，使得在该示例的位置的磁场约为5 mT的。例如，如果线圈的内半径为5毫米，宽度为8.5毫米，风0.12毫米直径导线2000绕组。设置产生500万吨在f 2 = 61赫兹。 </li></ol><img alt="图1" src="/files/ftp_upload/53869/53869fig1.jpg" /> 图1的p FMMD的示意图设置两个测量头电连接到彼此。将样品放置在头之间的空间。检测线圈（+）测量样品信号，反卷绕检测线圈（ - ）作为参考，以从高频激磁线圈抵消直接字段。放大器 - 前置放大器，X - 混频器，低通滤波器 - 低通滤波器，DAQ - 数据采集。目标="_空白"&gt;点击此处查看该图的放大版本。 2.构建测量头<ol><li>构造的p FMMD使得连接上方和下方的样品两套激发和检测线圈。每一组线圈包括一个低频驱动器线圈，高频激磁线圈，以及包含在轴向梯度仪配置两个相对伤口拾取线圈的差动检测线圈。 <ol><li>为了允许至少一个激励线圈相对于所述差分检测线圈的调节，以便能够在高频激励的直接感应平衡到检测线圈。例如，安装在一个线程允许励磁线圈与检测线圈的相对运动的励磁线圈。在p FMMD的示意图示于图1; 图2示出了技术图纸和设置的照片。详细线圈的参数列于表1中 。 </li></ol></li><li>安装线圈组上方和上一个刚性支撑样品的下方，与同轴取向，参见图1和2。确保两个线圈组不振动相对于彼此。 </li><li>通过施加高频电流，从而相应激励线圈组，它们之间的不同的相对位置，同时在与检测线圈组这个频率测量所检测的信号，使用的设备，如调整测量头的高频平衡示波器或锁定放大器。 <ol><li>调整直接感应电压低至几毫伏， 即直接诱导超过1000倍的抑制。通过观察励磁电流和检测的电压之间的相移确定的可调节的限制。在最小，感应电压为90°相移作为比较d可直接诱导。 </li></ol></li></ol><img alt="图2" src="/files/ftp_upload/53869/53869fig2.jpg" /> 图2.技术图纸和p FMMD头部的照片。沿一垂直平面的横截面（左上）和一个水平面（左下）中示出以及线圈卷绕前的照片的开测量头的。 1 - 铝的支持，2 - 线圈前者用于检测线圈，3 - 螺纹线圈前者为励磁线圈，可上升/下跌的旋转，4 - 样品支撑板，5 - 铝盖，6 - 样塞的支持，7 - 止动件在x方向，8 -挡块在y方向上 。 6 - 8为扫描被除去。在p FMMD头的大小为77毫米×68毫米×29毫米。 <a href="https://www.jove.com/files/ftp_upload/53869/53869fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 3.设置测量电子<ol><li>配置EXCI塔季翁部分，由两个振荡器和功率放大器为低频驱动器线圈和高频励磁线圈。 <ol><li>设置低频驱动器部分，包括振荡器和用于低频率f 2的功率放大器。计算放大器，使得它提供所需的电流以产生在驱动线圈5 mT的领域的力量。在这里，使用直接数字合成（DDS）芯片的可编程振荡器。采用高速缓冲作为功率放大器。 </li><li>设置高频激发部分，包括振荡器和用于高频率f 1的功率放大器。设置功率放大器，使得它提供所需的电流，以产生在励磁线圈约0.5 mT的领域。使用DDS芯片和一个高速缓冲分别作为振荡器和功率放大器。 </li></ol></li><li>配置检测部，包括一个preamplifie的R，第一混频器，以从高频率f 1，中间放大器和滤波器，一个第二混频器从两倍的低频2·解调f 2和最终的过滤器和输出驱动器解调。可替代地，使用两个锁定放大器来实现检测电子。 <ol><li>设置前置放大器级。选择输入运算放大器（OP），考虑到检测线圈和增益带宽积的阻抗。执行噪声优化过程，考虑到指定的电压噪声和OP的电流噪声，如在参考文献说明。 10.选择具有约100中的第一阶段的扩增高速低噪声运算放大器。后续阶段不是关键，但检查输出信号保持在电压范围内， 即，由于超载不失真。这里，使用具有4.3倍的放大的低噪声JFET输入运算放大器。 </li><li>设置在FIRST解调级中，以高频率f 1中的放大的信号相乘。使用模拟乘法器芯片，以实现对解调的可调相位从第二个独立的DDS芯片引用它。或者，使用锁定放大器作为前置放大器（3.2.1），第一解调器（3.2.2）和高频发生器（3.1.2）。 </li><li>设置在中间放大和滤波级。实现的低通滤波器，使得在2·f 2 的道次信号频率原状而在f 1和2· 女 1寄生高频成分被有效地抑制。通过用大约100总放大选择两个通用运算放大器选择合适的中间放大，例如。 </li><li>设置在第二解调级，滤波和放大的信号与低频率的两倍2·乘以f 2 的 。使用模拟乘法器芯片和从第四分开DDS芯片引用它，以实现用于解调一个可调相。可替代地，使用能够二次谐波解调作为中间放大器（3.2.3）中，在二次谐波（3.2.4）第二解调器和低频发生器（3.1.1）的一个锁定放大器。 </li><li>设置最终放大和滤波级。实现的低通滤波器，使得在扫描频率的信号频率通过原状，而在4寄生高频成分·f 2 的被有效地抑制。选择合适的最终放大，考虑到所需的输出电压范围。使用两个通用运算放大器约10共放大。 </li></ol></li></ol> 4.设置2D扫描仪<ol><li>装入2D扫描器，使得运动平面垂直于线圈的轴线。 </li><li>控制二维扫描仪和同步acquiri纳克为了获得使用写在编程语言的Python一个自制的脚本平面样品的FMMD信号的2D图像从测量电子输出电压。 </li></ol> 5.准备样品<ol><li>使用直径为50纳米至100纳米，磁赤铁矿颗粒磁铁矿颗粒的直径为1微米，其中浓度为25.0毫克/毫升。通过在水中的磁性粒子溶解，使用磁体将它们分开并丢弃水洗涤溶液。重复该过程三次。稀磁性粒子溶液到十分之一用蒸馏水。 </li><li>通过活检冲床冲孔吸收吸墨纸件准备用直径为2.0 mm纸张颗粒样品。浸泡其中在不同浓度的磁珠溶液30秒，并让他们在空气中干燥。这里，可使用的0.04，0.2，1，5和25毫克/毫升100纳米大小的颗粒的浓度。 </li><li>使用nitrocellulos制备样品尺寸个2.0毫米×18.0毫米ê膜。与未稀释的1微米直径的颗粒溶液浸泡该膜。准备由均匀浸泡膜一个样本，和另一个通过一个浓度梯度。通过浸泡在膜的端部在与不同浓度的珠粒溶液中，产生的浓度梯度（ 图5）执行此操作。 </li><li>制备于10μl体积的毛细管的样品，外径400微米，长40毫米。填充未稀释的50纳米直径的粒子溶液的毛细管。制备具有20倍稀释液的第二微管（1.9毫升水混合100微升未稀释溶液）。 </li></ol> 6.执行2D FMMD扫描<ol><li>根据平面尺寸A×B的样品的选择扫描区。在扫描软件输入值。 </li><li>选择步进方向。通常情况下，这两个平面尺寸的短，让我们把它叫做b </青霉&gt;，将被选择为，因为需要较少的步骤，从而减少加速和减速阶段的步进方向。 </li><li>选择扫描速度v，以考虑由于低通滤波信号还原，见讨论。调整的速度1和7毫米/秒之间的值。输入在扫描软件中的值。 </li><li>选择步进距离ΔB，考虑到它不必比实现的空间分辨率更小，总扫描时间t，这将是至少T = A / V·B /Δb +1）。输入在软件步进距离。 </li><li>安装在2D扫描仪的样本。修复它使用胶带塑料板。 </li></ol><img alt="图3" src="/files/ftp_upload/53869/53869fig3.jpg" /> 图3.对FMMD测量设置的照片。样品贴有塑料支架上的胶带由电机移动阶段（左）。然后将样品在p FMMD头（右）扫描。 <a href="https://www.jove.com/files/ftp_upload/53869/53869fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <ol start="6"><li>按下启动按钮执行扫描。 图5和6盖20.0毫米（X轴）的×25.0毫米（y轴）区域，扫描即 ，六25mm长痕量沿y轴扫描，以在x方向4.0毫米步骤，在一个阶段的速度为1.0毫米/秒。这相当于约2分钟的扫描时间。 </li></ol><img alt="图4" src="/files/ftp_upload/53869/53869fig4.jpg" /> 图4.图形用户扫描软件的接口 ，扫描参数在此输入。测量是通过按下红色按钮启动。 7.图像处理<ol><li>使用homemad原始数据转换成矩阵形式在python脚本ë。在一个2列逗号分隔值（CSV）格式文件多余的值记录整个扫描的原始数据一起。额外的列指示踩踏动作期间捕获相应的数据。该脚本片段在额外的列值的每一个变化的原始数据列，并删除步进运动过程中的数据段。它也通过将剩余的连续段成矩阵的行或列构建所得矩阵和矩阵写入CSV格式文件。 注意:使用python脚本生成该研究对FMMD图像。的pyplot.contour函数和从matplotlib库蟒的pyplot.imshow功能累积地用于制备轮廓和背景颜色，分别。 </li></ol>

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The authors have nothing to disclose.

测量技术利用了超顺磁性粒子的磁化曲线的非线性。双面测量头同时施加不同频率的两个磁激励场的样品，一个低频率（f 2）成分以驱动颗粒进入磁饱和和高的频率（f 1）探测场来测量非线性磁响应。尤其，入射场的两个谐波， 男 · 女 1和n·f 2和总和的频率中，M· 女 1 + N·f 2 ?...

<html>磁性纳米颗粒（MNP）已发现在分子生物学和医学， 即广泛应用，用于生物分子的操纵和单电池1，用于选择性标记进行检测，2，3靶实体染色质调制，4和mRNA分离和癌症治疗5由于其超顺属性，它们是用于医疗成像特别有用。它们可以通过使用超导量子干涉仪（SQUID）检测服务，例如，如造影剂或示踪剂磁共振成像（MRI）或用于磁敏成像2,6的超顺磁性纳米颗粒，得到了良好的对比度，以人类的不同组织体，其是dia-或顺7因此，颗粒可以方便地用于获得人体部位具有相对良好的空间分辨率和灵敏度的医学图像。8 通过GLEICH和Weizenecker 9中引入帐篷"&gt;磁粉成像（MPI）技术利用粒子的磁化非线性的。在零或弱磁场偏差，MNP对频率f的交流激励的反应是强烈的，由于其大的易感性，尤其是粒子的非线性磁化引起谐波N·f的产生，其中n = 2，3，4 ...在高磁场偏置，谐波响应变弱，因为粒子被磁饱和，在在MPI技术中，样品完全除自由场线（FFL）或无场点（FFP）磁化。只有粒子靠近这条线或点将有助于样品的非线性响应。随着适当的接收器线圈的FFP和就业运动，GLEICH和Weizenecker获得MPI图片包含有1mm的空间分辨率。 为了获得MNP的空间分布的信息，这两种方法通常被使用的，传感器的相对于该样品，或FFL / FFP的运动由电磁铁装置2,3的机械运动在后一种情况下，图像重建技术像谐波空间MPI 3或X-空间MPI 10，11，12是必需的。 MPI的空间分辨率被激发和检测线圈的卷积特性以及由磁场梯度的特性来确定。这允许图像重建算​​法，以获得在原始分辨率，这是由拾取线圈的大小和距离以及由麦克斯韦方程支配的磁场分布确定的更高的分辨率。 一个MPI扫描器通常由强磁体用于磁化整个样本，以操纵跨越样品FFL或FFP可控线圈系统，高频激励下Ñ​​线圈系统，以及用于拾取来自样品的非线性响应的检测线圈系统。的FFL / FFP通过样品体积连续移动而从该不饱和样品区的谐波响应被记录。为了避免装配试样放入扫描仪的问题，一个单面MPI扫描器已由格拉夫等人 13表明，但是在降低性能为代价的。如果样品是由磁体和线圈包围得到最好的结果。因为样本具有除FFL / FFP区域充分磁化，该技术需要用水冷却相对大和强烈的磁铁，从而导致相当笨重的MPI系统。 我们的方法是基于频率在超顺磁性粒子的非线性磁化曲线混合14当超paramagnets以两个不同的频率（f1和f2 &lt;暴露于磁场/ EM&gt; 2），较线性组合·M·˚F和频1 + N·F 2（整数数m，生成N）。结果表明，这些组件的外观是高度特异性的粒子的磁化曲线的非线性。15换句话说，当MNP样品在频率f 2和频率的探测场同时暴露于一个驱动磁场F 1，将颗粒在频率f生成响应字段1 + 2·f 2 的 。无磁性非线性样品这个总和频率不会存在，因此特异性极高。我们称这种方法"混频磁性检测"（FMMD）。实验已经证实，该技术产生的颗粒浓度数量级大于四个数量的动态范围。14 &lt;P类="jove_content"&gt;相反典型MPI仪表，平面混频磁性检测（对- FMMD）方法不需要接近磁化样品到饱和，因为总和频率分量f的产生1 + 2· 女 图2是在零静态偏置字段最大14因此，需要有强烈的和笨重的磁体被减轻。事实上，该测量头的外部尺寸是仅77毫米×68毫米×29毫米。为了比较，MPI设置通常米尺寸7的缺点，但是，是该技术只限于平面样品以2mm的当前设置的最大厚度。样品必须被相对扫描到双面测量头。重新构造允许较厚的样品是可能的，但要在空间分辨率的损失进行交易。 在此基础上FMMD技术，我们提出了一个特殊类型的MPI的DETEC器为平面样品，即所谓的"平面混频磁性检测"（对 - FMMD）扫描仪。这一原则已被最近出版的17本工作中，我们专注于技术和目前的协议的方法，如何建立这样的扫描仪，以及如何执行扫描。它已经表明MPI可应用于医疗诊断目的，例如心血管或癌症成像。16，18，19因此，我们认为，新的MPI扫描器可用于广泛的潜在应用， 例如 ，用于测量磁性粒子分布组织切片。

<table>
	<tbody>
		<tr>
			<td>Magnetic particles &#34;SiMAG Silanol&#34;</td>
			<td>Chemicell (http://www.chemicell.com)</td>
			<td>1101-5</td>
			<td>Aqueous dispersion of magnetic silica particles, Maghemite, dia. 1 &#181;m</td>
		</tr>
		<tr>
			<td>Magnetic nanoparticles &#34;fluidMAG-Amine&#34;</td>
			<td>Chemicell (http://www.chemicell.com)</td>
			<td>4121-5</td>
			<td>Aqueous dispersion of magnetic nanoparticles, Magnetite, dia. 50 nm</td>
		</tr>
		<tr>
			<td>Microtube 10 &#181;l</td>
			<td>Hirschmann Laborger&#228;te (http://www.hirschmann-laborgeraete.de/?sc_lang=en)</td>
			<td></td>
			<td>volume 10 &#181;l, outer diameter 400 &#181;m, length 40 mm</td>
		</tr>
		<tr>
			<td>Nitrocellulose Membrane Biodyne B</td>
			<td>Thermo Scientific (http://www.thermoscientific.com)</td>
			<td>77016</td>
			<td>Biodyne B Nylon Membrane, 0.45 &#181;m, 8 cm x 12 cm</td>
		</tr>
		<tr>
			<td>DDS chip AD9834</td>
			<td>Analog Devices (http://www.analog.com)</td>
			<td>AD9834</td>
			<td>20 mW Power, 2.3 V to 5.5 V, 75 MHz Complete DDS</td>
		</tr>
		<tr>
			<td>Operational Amplifier AD829</td>
			<td>Analog Devices (http://www.analog.com)</td>
			<td>AD829</td>
			<td>High Speed, Low Noise Video Op Amp</td>
		</tr>
		<tr>
			<td>Analog Multiplier MPY634</td>
			<td>Texas Instruments (http://www.ti.com)</td>
			<td>MPY634</td>
			<td>Wide Bandwidth Precision Analog Multiplier</td>
		</tr>
		<tr>
			<td>High-Speed Buffer BUF634</td>
			<td>Texas Instruments (http://www.ti.com)</td>
			<td>BUF634</td>
			<td>250mA High-Speed Buffer</td>
		</tr>
		<tr>
			<td>Operational Amplifier OPA627</td>
			<td>Texas Instruments (http://www.ti.com)</td>
			<td>OPA627</td>
			<td>Precision High-Speed Difet(R) Operational Amplifiers</td>
		</tr>
		<tr>
			<td>Operational Amplifier TL072</td>
			<td>Texas Instruments (http://www.ti.com)</td>
			<td>TL072</td>
			<td>Dual Low-Noise JFET-Input General-Purpose Operational Amplifier</td>
		</tr>
		<tr>
			<td>Lock-In Amplifier SR830</td>
			<td>Stanford Instruments (http://www.thinksrs.com)</td>
			<td>SR830</td>
			<td>100 kHz DSP lock-in amplifier</td>
		</tr>
		<tr>
			<td>XYZ motorized stage</td>
			<td>Sciencetown, Incheon, Korea (http://mkmsll.en.ec21.com/)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cleanroom wiper</td>
			<td>Seoul Semitech Co (http://www.seoulsemi.com)</td>
			<td>CF-909</td>
			<td>dimension 2.0 mm &#215; 18 mm</td>
		</tr>
	</tbody>
</table>

frequency mixing magnetic detection scanner for imaging magnetic particles in planar samples

平面混频执行扁平样品的磁粒子成像（MPI）磁探测（P-FMMD）扫描仪的设置提出。它由上安装在U形支撑件的腿的样本两侧的两个磁测量磁头。样品被局部暴露于由两个不同的频率，有更强的组分在约77千赫的磁激励场和一个较弱的磁场在61赫兹。超顺磁性粒子的非线性磁化特性引起的互调产物的产生。的高频和低频磁场入射到磁非线性颗粒的选定和频分量由解调电子记录。在对比常规的MPI扫描器，由于两个频率的混合发生在本地对 - FMMD不需要强磁场的整个样品中的应用。因此，样品的横向尺寸只是由扫描范围和支撑的限制。然而，样品的高度决定了空间分辨率。在当前的设置，是限定于2毫米。作为例子，我们提出从样品中硅醇基基质，并与氨基硅烷基50纳米磁性颗粒1微米直径的颗粒磁赤铁矿收购了两家20毫米×25毫米毫米P-FMMD图像。的结果表明，该新型的MPI扫描器可以应用于生物薄样品的分析和用于医疗诊断目的。

图5a示出的内双差分检测线圈的所计算出的灵敏度分布的坐标x的在样品平面的函数和y。它是通过确定在由所有四个检测线圈产生的中央平面中的所有点（X，Y）的磁场叠加在逆方法算出。相反，这个判断上述检测线圈对在每个这些点的磁矩灵敏度。计算被逼近线圈的高度可以忽略不计长的线圈进行。因此，在图5a中所示...

Watch this Scientific Journal Video about Frequency Mixing Magnetic Detection Scanner for Imaging Magnetic Particles in Planar Samples at JoVE.com

Frequency Mixing Magnetic Detection Scanner for Imaging Magnetic Particles in Planar Samples

一种用于成像平面样品中的磁性粒子扫描器用的是平面混频磁性检测技术的发展。从颗粒的非线性nonhysteretic磁化磁互调产物的反应后的两频率激励被记录。它可用于取薄的生物样品的二维图像。

混频磁探测仪在平面样品成像磁性微粒

The setup of a planar Frequency Mixing Magnetic Detection (p-FMMD) scanner for performing Magnetic Particles Imaging (MPI) of flat samples is presented. ...

frequency-mixing-magnetic-detection-scanner-for-imaging-magnetic

Research

JoVE Journal

Engineering

9.5K 次观看.  Electronics & Telecommunication Research Institute (ETRI). 一种用于成像平面样品中的磁性粒子扫描器用的是平面混频磁性检测技术的发展。从颗粒的非线性nonhysteretic磁化磁互调产物的反应后的两频率激励被记录。它可用于取薄的生物样品的二维图像。 

视频: Frequency Mixing Magnetic Detection Scanner for Imaging Magnetic Particles in Planar Samples

Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing

The application of femtosecond four-wave mixing to the study of fundamental properties of diluted magnetic semiconductors ((s,p)-d hybridization, spin-flip scattering) is described, using experiments on GaMnAs as a prototype III-Mn-V system.&#160; Spectrally-resolved and time-resolved experimental configurations are described, including the use of zero-background autocorrelation techniques for pulse optimization.&#160; The etching process used to prepare GaMnAs samples for four-wave mixing experiments is also highlighted.&#160; The high temporal resolution of this technique, afforded by the use of short (20 fsec) optical pulses, permits the rapid spin-flip scattering process in this system to be studied directly in the time domain, providing new insight into the strong exchange coupling responsible for carrier-mediated ferromagnetism.&#160; We also show that spectral resolution of the four-wave mixing signal allows one to extract clear signatures of (s,p)-d hybridization in this system, unlike linear spectroscopy techniques.&#160;&#160; This increased sensitivity is due to the nonlinearity of the technique, which suppresses defect-related contributions to the optical response. This method may be used to measure the time scale for coherence decay (tied to the fastest scattering processes) in a wide variety of semiconductor systems of interest for next generation electronics and optoelectronics.

The technique of femtosecond four-wave mixing is described, including spectrally-resolved and time-resolved configurations. We illustrate the utility of this technique for the investigation of crucial physical properties in the III-V diluted magnetic semiconductors, afforded by its nonlinearity and high temporal resolution.

The application of femtosecond four-wave mixing to the study of fundamental properties of diluted magnetic semiconductors ((s,p)-d hybridization, ...

科研

工程学

Phase Diagram Characterization Using Magnetic Beads as Liquid Carriers

Magnetic beads with ~1.9 &#181;m average diameter were used to transport microliter volumes of liquids between contiguous liquid segments with a tube for the purpose of investigating phase change of those liquid segments. The magnetic beads were externally controlled using a magnet, allowing for the beads to bridge the air valve between the adjacent liquid segments. A hydrophobic coating was applied to the inner surface of the tube to enhance the separation between two liquid segments. The applied magnetic field formed an aggregate cluster of magnetic beads, capturing a certain liquid amount within the cluster that is referred to as carry-over volume. A fluorescent dye was added to one liquid segment, followed by a series of liquid transfers, which then changed the fluorescence intensity in the neighboring liquid segment. Based on the numerical analysis of the measured fluorescence intensity change, the carry-over volume per mass of magnetic beads has been found to be ~2 to 3 &#181;l/mg. This small amount of liquid allowed for the use of comparatively small liquid segments of a couple hundred microliters, enhancing the feasibility of the device for a lab-in-tube approach. This technique of applying small compositional variation in a liquid volume was applied to analyzing the binary phase diagram between water and the surfactant C12E5 (pentaethylene glycol monododecyl ether), leading to quicker analysis with smaller sample volumes than conventional methods.

Here, we present a protocol to investigate multi-component phase diagrams using externally controlled magnetic beads as liquid carriers in a lab-in-tube approach. This approach can aid in applications that seek to gather further information on phase change in complex liquid systems.

相图表征使用磁珠用作液体载体

Magnetic beads with ~1.9 &#181;m average diameter were used to transport microliter volumes of liquids between contiguous liquid segments with a tube for ...

Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

Because of the importance and extensive use of palladium, gold and cobalt metals in high-technology equipment, their recovery and recycling constitute an important industrial challenge. The metal recovery system described herein is a simple, low-cost means for the effective detection, removal, and recovery of these metals from the urban mine.

检测和钯的回收，从城市矿山黄金和钴金属使用标有纳米货车车轮形的孔隙新型传感器/吸附剂

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in ...

Use of a Multi-compartment Dynamic Single Enzyme Phantom for Studies of Hyperpolarized Magnetic Resonance Agents

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due to fundamental constraints imposed by the hyperpolarized state, exotic imaging and reconstruction techniques are commonly used. A practical system for characterization of dynamic, multi-spectral imaging methods is critically needed. Such a system must reproducibly recapitulate the relevant chemical dynamics of normal and pathological tissues. The most widely utilized substrate to date is hyperpolarized [1-13C]-pyruvate for assessment of cancer metabolism. We describe an enzyme-based phantom system that mediates the conversion of pyruvate to lactate. The reaction is initiated by injection of the hyperpolarized agent into multiple chambers within the phantom, each of which contains varying concentrations of reagents that control the reaction rate. Multiple compartments are necessary to ensure that imaging sequences faithfully capture the spatial and metabolic heterogeneity of tissue. This system will aid the development and validation of advanced imaging strategies by providing chemical dynamics that are not available from conventional phantoms, as well as control and reproducibility that is not possible in vivo.

A multi-compartment dynamic phantom is used to simulate some biology of interest for metabolic studies using hyperpolarized magnet resonance agents.

一个多腔动态单一酶幻影超极化磁共振剂研究的用途

Imaging of hyperpolarized substrates by magnetic resonance shows great clinical promise for assessment of critical biochemical processes in real time. Due ...

Resonance Fluorescence of an InGaAs Quantum Dot in a Planar Cavity Using Orthogonal Excitation and Detection

The ability to perform simultaneous resonant excitation and fluorescence detection is important for quantum optical measurements of quantum dots (QDs). Resonant excitation without fluorescence detection &#8211; for example, a differential transmission measurement &#8211; can determine some properties of the emitting system, but does not allow applications or measurements based on the emitted photons. For example, the measurement of photon correlations, observation of the Mollow triplet, and realization of single photon sources all require collection of the fluorescence. Incoherent excitation with fluorescence detection &#8211; for example, above band-gap excitation &#8211; can be used to create single photon sources, but the disturbance of the environment due to the excitation reduces the indistinguishability of the photons. Single photon sources based on QDs will have to be resonantly excited to have high photon indistinguishability, and simultaneous collection of the photons will be necessary to make use of them. We demonstrate a method to resonantly excite a single QD embedded in a planar cavity by coupling the excitation beam into this cavity from the cleaved face of the sample while collecting the fluorescence along the sample&#39;s surface normal direction. By carefully matching the excitation beam to the waveguide mode of the cavity, the excitation light can couple into the cavity and interact with the QD. The scattered photons can couple to the Fabry-Perot mode of the cavity and escape in the surface normal direction. This method allows complete freedom in the detection polarization, but the excitation polarization is restricted by the propagation direction of the excitation beam. The fluorescence from the wetting layer provides a guide to align the collection path with respect to the excitation beam. The orthogonality of the excitation and detection modes enables resonant excitation of a single QD with negligible laser scattering background.

Resonant excitation of a single self-assembled quantum dot can be achieved using an excitation mode orthogonal to the fluorescence collection mode. We demonstrate a method using the waveguide and Fabry-Perot modes of a planar microcavity surrounding the quantum dots. The method allows complete freedom in the detection polarization.

用正交激励和检测方法研究平面腔内铟量子点的共振荧光

The ability to perform simultaneous resonant excitation and fluorescence detection is important for quantum optical measurements of quantum dots (QDs). ...

Near-Infrared Temperature Measurement Technique for Water Surrounding an Induction-heated Small Magnetic Sphere

A technique to measure the temperature of water and non-turbid aqueous media surrounding an induction-heated small magnetic sphere is presented. This technique utilizes wavelengths of 1150 and 1412 nm, at which the absorption coefficient of water is dependent on temperature. Water or a non-turbid aqueous gel containing a 2.0-mm- or 0.5-mm-diameter magnetic sphere is irradiated with 1150 nm or 1412 nm incident light, as selected using a narrow bandpass filter; additionally, two-dimensional absorbance images, which are the transverse projections of the absorption coefficient, are acquired via a near-infrared camera. When the three-dimensional distributions of temperature can be assumed to be spherically symmetric, they are estimated by applying inverse Abel transforms to the absorbance profiles. The temperatures were observed to consistently change according to time and the induction heating power.

A technique utilizing wavelengths of 1150 and 1412 nm to measure the temperature of water surrounding an induction-heated small magnetic sphere is presented.

感应加热小磁球周围水近红外测温技术

A technique to measure the temperature of water and non-turbid aqueous media surrounding an induction-heated small magnetic sphere is presented. This ...

Fabrication of Magnetic Nanostructures on Silicon Nitride Membranes for Magnetic Vortex Studies Using Transmission Microscopy Techniques

Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared on transparent membranes which are very fragile and difficult to manipulate. We present processes for the fabrication of samples with magnetic micro- and nanostructures with spin configurations forming magnetic vortices suitable for Lorentz transmission electron microscopy and magnetic transmission x-ray microscopy studies. The samples are prepared on silicon nitride membranes and the fabrication consists of a spin coating, UV and electron-beam lithography, the chemical development of the resist, and the evaporation of the magnetic material followed by a lift-off process forming the final magnetic structures. The samples for the Lorentz transmission electron microscopy consist of magnetic nanodiscs prepared in a single lithography step. The samples for the magnetic x-ray transmission microscopy are used for time-resolved magnetization dynamic experiments, and magnetic nanodiscs are placed on a waveguide which is used for the generation of repeatable magnetic field pulses by passing an electric current through the waveguide. The waveguide is created in an extra lithography step.

A protocol for the fabrication of magnetic micro- and nanostructures with spin configurations forming magnetic vortices suitable for transmission electron microscopy (TEM) and magnetic transmission x-ray microscopy (MTXM) studies is presented.

用透射显微技术制备氮化硅薄膜磁性纳米结构的研究

Electron and x-ray magnetic microscopies allow for high-resolution magnetic imaging down to tens of nanometers. However, the samples need to be prepared ...

A Random-displacement Measurement by Combining a Magnetic Scale and Two Fiber Bragg Gratings

Long-distance displacement measurements using optical fibers have always been a challenge in both basic research and industrial production. We developed and characterized a temperature-independent fiber Bragg grating (FBG)-based random-displacement sensor that adopts a magnetic scale as a novel transferring mechanism. By detecting shifts of two FBG center wavelengths, a full-range measurement can be obtained with a magnetic scale. For identification of the clockwise and counterclockwise rotation direction of the motor (in fact, the direction of movement of the object to be tested), there is a sinusoidal relationship between the displacement and the center wavelength shift of the FBG; as the anticlockwise rotation alternates, the center wavelength shift of the second FBG detector shows a leading phase difference of around 90&#176; (+90&#176;). As the clockwise rotation alternates, the center wavelength shift of the second FBG displays a lagging phase difference of around 90&#176; (-90&#176;). At the same time, the two FBG-based sensors are temperature independent. If there is some need for a remote monitor without any electromagnetic interference, this striking approach makes them a useful tool for determining the random displacement. This methodology is appropriate for industrial production. As the structure of the whole system is relatively simple, this displacement sensor can be used in commercial production. In addition to it being a displacement sensor, it can be used to measure other parameters, such as velocity and acceleration.

A protocol to create a full-range linear displacement sensor, combining two packaged fiber Bragg grating detectors with a magnetic scale, is presented.

通过组合磁量表和两个光纤布拉格光栅进行随机位移测量

Long-distance displacement measurements using optical fibers have always been a challenge in both basic research and industrial production. We developed ...

Enrich and Expand Rare Antigen-specific T Cells with Magnetic Nanoparticles

We have developed a tool to both enrich and expand antigen-specific T cells. This can be helpful in cases such as to A) detect the existence of antigen-specific T cells, B) probe the dynamics of antigen-specific responses, C) understand how antigen-specific responses affect disease state such as autoimmunity, D) demystify heterogeneous responses for antigen-specific T cells, or E) utilize antigen-specific cells for therapy. The tool is based on a magnetic particle that we conjugate antigen-specific and T cell co-stimulatory signals, and that we term as artificial antigen presenting cells (aAPCs). Consequently, since the technology is simple to produce, it can easily be adopted by other laboratories; thus, our purpose here is to describe in detail the fabrication and subsequent use of the aAPCs. We explain how to attach antigen-specific and co-stimulatory signals to the aAPCs, how to utilize them to enrich for antigen-specific T cells, and how to expand antigen-specific T cells. Furthermore, we will highlight engineering design considerations based on experimental and biological information of our experience with characterizing antigen-specific T cells.

Antigen-specific T cells are difficult to characterize or utilize in therapies due to their extremely low frequency. Herein, we provide a protocol to develop a magnetic particle which can bind to antigen-specific T cells to enrich these cells and then to expand them several hundred-fold for both characterization and therapy.

利用磁性纳米粒子丰富和扩大罕见抗原特异性 t 细胞

We have developed a tool to both enrich and expand antigen-specific T cells. This can be helpful in cases such as to A) detect the existence of ...

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing

We present a protocol for performing gas spectroscopy using infrared degenerated four-wave mixing (IR-DFWM), for the quantitative detection of gas species in the ppm-to-single-percent range. The main purpose of the method is the spatially resolved detection of low-concentration species, which have no transitions in the visible or near-IR spectral range that could be used for detection. IR-DFWM is a nonintrusive method, which is a great advantage in combustion research, as inserting a probe into a flame can change it drastically. The IR-DFWM is combined with upconversion detection. This detection scheme uses sum-frequency generation to move the IR-DFWM signal from the mid-IR to the near-IR region, to take advantage of the superior noise characteristics of silicon-based detectors. This process also rejects most of the thermal background radiation. The focus of the protocol presented here is on the proper alignment of the IR-DFWM optics and on how to align an intracavity upconversion detection system.

Here, we present a protocol to perform sensitive, spatially resolved gas spectroscopy in the mid-infrared region, using degenerate four-wave mixing combined with upconversion detection.

用于定量气体传感的红外退化四波融合与上转换检测

We present a protocol for performing gas spectroscopy using infrared degenerated four-wave mixing (IR-DFWM), for the quantitative detection of gas species ...