This work has been financially supported by Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology (No. 25248027 to M.S.).

1.样品制备<ol><li> 温度响应单体的纯化 <ol><li>在100毫升甲苯中溶解20g的N- -isopropylacrylamide的（NIPA）。 </li><li>过滤下抽吸该溶液，以消除粉尘。 </li><li>混合用500ml石油醚滤液。 </li><li>放置在反应容器在冰 - 水浴中。 </li><li>搅拌溶液，直到单体被沉淀（通常为30分钟）。 </li><li>过滤下抽吸该溶液，得到沉淀的单体。 </li><li>干燥在减压下（100帕）过夜单体。 </li></ol></li><li> 温度响应性聚合物溶液的制备 <ol><li>脱气20毫升去离子水，使用隔膜泵1.0分钟。 </li><li>溶解780.8毫克的纯化NIPA的在9.5毫升脱气和去离子水。 </li><li>放置在反应容器在冰 - 水浴中。 </li><li>屏蔽从反应由覆盖用铝箔装置的光。 </li><li>轻轻搅拌该溶液10分钟，同时通过连接于气瓶用管枪头轻轻引入Ar气的适度流动。 </li><li>添加11.9微升的N，N，N&#39;，N&#39;四甲基乙二胺经由微量溶液。 </li><li>搅拌该溶液1.0分钟，同时引入Ar气，如在步骤1.2.5提及。 </li><li>在搅拌的同时将样品，溶解4.0毫克过硫酸铵在0.5毫升脱气和去离子水。 </li><li>混合样品溶液（从步骤1.2.7）和过硫酸铵溶液（来自步骤1.2.8）。 </li><li>搅拌该溶液30秒，同时引入Ar气，如在步骤1.2.5提及。 </li><li>用铝箔覆盖该溶液，并保持它在冰箱（4℃）过夜。 </li></ol></li><li> 坐骑样品的制备 <ol><li>将样品溶液的60微升（从步1.2.11）的一腔幻灯片。 </li><li>封面用圆形玻璃盖的解决方案。要小心，不要陷气泡。 </li><li>除去使用微量和实验室湿巾过量的溶液。 </li><li>密封胶水样品。让在室温（通常为6小时）的胶干燥。 </li><li>通过以下步骤1.3.1-1.3.4制备填充有0.1重量％的聚苯乙烯胶乳（100nm的粒径）悬浮另一个滑动。该滑动用作标准。 </li></ol></li></ol>用动态光散射显微镜2.粒度测量<ol><li> 该仪器的优化 <ol><li>放置聚苯乙烯胶乳悬浮滑动（从步骤1.3.5）在倒置显微镜的阶段。玻璃盖面应朝下。 </li><li>放置在检测器的前面的光束阻尼器（雪崩光电二极管和自相关）。 </li><li>施加激光束（固态激光器，λ= 488纳米，30毫瓦，连续波）到样品通过物镜（10×）。的反射光的一部分穿过显微镜的发射镜，并通过CCD照相机观察到安装在显微镜（ 图1）的侧端口。 </li><li>调整物镜的高度由从低到高的位置移动物镜的高度，以设定在样品悬浮液的焦点。在此过程中，被反射的图像被聚焦三次：在盖玻璃的表面上，在玻璃盖和样品之间的界面，并在样品和空穴载玻片之间的接口。设置第二个和第三个点之间的焦点。 </li><li>通过改变激光功率衰减的散射光强度。 </li><li>通过在检测器的前面取出光束阻尼器引进的散射光进入检测器。此单元测量的光强的时间相关性。 </li><li>设置一个针孔（φ= 50微米）betwEEN显微镜和检测器来实现共焦的效果。调节针孔的位置在检测器以最大化光强度。 </li><li>通过经由计算机启动所述相关器的操作测量30秒散射光强度的时间相关函数。测得的相关函数通常表示为g（2）（T） - 1，其中t是相关时间4和<img alt="式（1）" src="/files/ftp_upload/54885/54885eq1.jpg" /> 。这里，I（t）是在时间t和（•••）T是时间平均散射光强度。衰减时间将约为0.1毫秒。 </li><li>调整着力点，获得了广泛的时间相关函数的初始幅度（ 克 （2）（T = 0） - 1）。 注：初始振幅强烈影响的反射光的量。通过移动焦点拖ARD玻璃盖和样品，反射光的量增加之间的接口。对于强光散射，如聚苯乙烯胶乳，初始振幅可以从0改变为1。然而，这是难以设置接近1为更常见的聚合物溶液的初始振幅，因为反射光的强度远高于散射光的。 </li><li>应用Laplace逆变换（使用约束正计划CONTIN 13,14）所获得的时间相关的函数来获取大小分布函数。在将初始振幅设定为小于0.2的情况下，水动力半径的分布函数会显示约100纳米，这是实际的半径（详见讨论）两次的尖峰。 </li></ol></li><li> 样品测量 <ol><li>设置了阶段温度至25℃。 </li><li>将带有聚NIPA（PNIPA）SOLUT准备了幻灯片离子显微镜的阶段（步骤1.3.4）。 </li><li>通过以下步骤2.1.4-2.1.8测量散射光强度的时间相关函数。如果初始振幅是大于0.2，通过以下步骤2.1.9调整焦点，以使时间相关函数的初始振幅小于0.2。一个小幅度的初始简化了分析。 </li><li>将舞台温度35℃，等到溶液变浑浊。的PNIPA溶液的低临界溶液温度（LCST）是32℃下15。 </li><li>通过以下步骤测量时间相关函数2.1.4-2.1.8。如果可行的话，调整焦点的位置，使时间相关函数小于0.2的初始振幅。为混浊的解决方案，它们的初始振幅趋于增加，因为散射光的强度增大而反射光的保持不变。 </li><li>应用拉普拉斯逆transformati上所获得的时间相关函数，得到的粒度分布的功能。请注意，实际的大小为一半的情况下所获得的值，其中初始振幅是小于0.2。 </li></ol></li></ol>

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The authors have nothing to disclose.

时间相关函数的初始振幅在很大程度上依赖于焦点， 如图2（a）中 。这看似矛盾的事实，即溶液是均质的（除了在界面处的薄层）8。在最初的振幅的这种变化是由于在反射光的量的变化。偏差理论16预测的初始振幅，A中 ，散射光强度，I s和反射光强度，I R，满足下式1 <img alt="公式（2）" src="/files/ftp_upload/54885/54885eq2.jpg" />这个公式表明，I R变得越大，越小A变得。因此，A通过设置靠近接口的焦点位置降低。表观扩散常数D A CAÑ通过在单分散的解决方案的情况下，拟合时间相关函数来获得： <img alt="公式3" src="/files/ftp_upload/54885/54885eq3.jpg" />哪里<img alt="公式4" src="/files/ftp_upload/54885/54885eq4.jpg" /> 。这里，n是溶剂（水，1.33）的折射率，θ是散射角（180°），和λ是光（514.5nm的）的波长。因为我们施加散射几何学，q的值是固定的。然而，这点是通过使用不同波长的光解决。请注意，任何类型的连续波激光源的可用来构造对DLS显微镜。由于小照射量，相干因子17估计为0.99以上，是可以忽略不计。对于多分散溶液，由逆拉普拉斯变换获得的D A的分布函数。偏差次eory还预测，D A是不一样的实际扩散常数D。这两个扩散常数满足以下公式： <img alt="公式5" src="/files/ftp_upload/54885/54885eq5.jpg" />扩散常数D被转换成使用爱因斯坦-Stokes方程4中的流体动力学半径R H。当A = 1，这种关系变得D A = D。在这种情况下，数据转换过程是相同的，对于共同的动态光散射。在图2（b）中所示的红色线对应于这种情况。与此相反，这种关系变为D A = 0.5 D钮 A的极限→0，因此，大小估计为两倍的实际大小为大时，A是小的（实际上，小于0.2），如图所示由图2（b）的蓝线</s仲&gt;。如果我们知道A是显著小，横轴可以移动， 如图2（c）所示 。原则上，我们可以D A转换成D代表A的任意值。在实践中，然而，最好是设定为比0.2的初始振幅小，由于简单的近似D A〜0.5ð成立。 动态光散射显微镜技术的突出特点是使用PNIPA解决方案演示。 PNIPA的下面和高于LCST构象已经使用小角中子散射15,18被广泛地研究。相比之下，动态光散射尚未用于PNIPA的LCST以上的分析，因为它的浊度19。这个问题是由动态光散射显微镜解决， 如图3（a）和（b）中 。这些聚集体的尺寸为几＆＃181;米，这不能由任一小角X射线/中子散射或常规的光散射技术获得。使用该系统的时间分辨的测量的温度变化过程中得到的聚集过程的信息。 动态光散射显微镜的缺点也被在图3中示出。为低于LCST的结果，时间相关函数强烈地受到本灰尘的极少量的（黑线在图3中）的影响。例如，该时间相关函数不完全衰减，即使在1.0秒的数量级相关时间。这是因为该装置（约1.0微米）的照射体积比照射与通常的动态光散射装置（大约100微米）显著小。在的情况下的散射光的强度较弱，信号被噪音掩盖，比如导致由s商场的量在溶液中的灰尘。因此，在如图3（b）中所示的三个峰可能不具有定量的重要性虽然尺寸的一般顺序是有意义的。另外，这样的弱散射体可以通过常规的动态光散射装置进行测定。 我们已经证明，在动态光散射显微镜使我们能够用相同的设置测量透明和混浊样本。由于样品中的光路长度短，该技术可以适用于强的光吸收的样品，如碳纳米管悬浮液20。此外，由于其高的空间分辨率，该技术可以适用于生物细胞。其应用到生物学，这种方法也可与其它成像技术，如荧光和拉曼成像相结合。因此，我们认为，在动态光散射显微镜为广泛研究领域的有力工具。

Particle size is one of the most fundamental properties of colloidal and polymer solutions. Numerous techniques are used to measure the particle size. Particle sizes of 1.0 &#181;m or larger can be measured directly using an optical microscope. For smaller particles, alternative techniques, such as laser diffraction, electron microscopy, or atomic force microscopy, are used2,3. Dynamic light scattering is a commonly-used technique for the measurement of particle size distributions in solutions4. The results obtained using this technique are not derived from images of the particles but from the characteristic time of the fluctuations in scattered light intensity. These fluctuations originate from Brownian motion, which is characterized by a diffusion constant. The size distribution is obtained from the distribution of diffusion constants using the Einstein-Stokes equation. Due to its simplicity, dynamic light scattering is widely used for the routine assessment of solutions, such as paints and food colloids.
Pretreatment is required for most of the techniques used for the particle size measurement of solution samples. In the case of electron microscopy and atomic force microscopy, the sample must be analyzed under vacuum conditions. Therefore, it is difficult to observe the samples in their native forms. Furthermore, for laser diffraction and dynamic light scattering, only diluted samples that are free from multiple scattering and light absorption can be measured. To overcome this difficulty, several new techniques have been proposed for the measurement of dynamic light scattering from undiluted, concentrated solutions, such as cross-correlation spectroscopy5,6, low-coherence dynamic light scattering7,8, diffusing-wave spectroscopy9,10, and differential dynamic microscopy11,12.
We have developed a new apparatus called a dynamic light scattering microscope1. This apparatus enables us to measure turbid samples without dilution by means of a confocal optical system in which multiple scattering is eliminated using a pinhole. However, the measurement procedure and data analysis are slightly more complicated than those of commercially-available instruments. This video explains the measurement procedure and data analysis in detail using the analysis of the temperature-responsive polymer, poly(N-isopropylacrylamide), as an example.

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			<td height="76" style="height:76px;width:216px;">N-isopropylacrylamide, 98%</td>
			<td style="width:89px;">Tokyo Chemical Industry Co., Ltd.</td>
			<td style="width:119px;">I0401</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="76">
			<td height="76" style="height:76px;width:216px;">toluene, 99%</td>
			<td style="width:89px;">Wako Pure Chemical Industries, Ltd.</td>
			<td style="width:119px;">201-01876</td>
			<td></td>
		</tr>
		<tr height="76">
			<td height="76" style="height:76px;width:216px;">petroleum ether, distillation temperature 30 ~ 60 &#176;C</td>
			<td style="width:89px;">Wako Pure Chemical Industries, Ltd.</td>
			<td style="width:119px;">169-22565</td>
			<td></td>
		</tr>
		<tr height="57">
			<td height="57" style="height:57px;width:216px;">N,N,N&#39;,N&#39;-tetramethylethylenediamine, 99%</td>
			<td style="width:89px;">Sigma</td>
			<td style="width:119px;">T9281</td>
			<td></td>
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			<td height="19" style="height:19px;width:216px;">ammonium persulfate, 98%</td>
			<td style="width:89px;">Sigma</td>
			<td style="width:119px;">248614</td>
			<td></td>
		</tr>
		<tr height="57">
			<td height="57" style="height:57px;width:216px;">polystyrene latex suspension, 1 wt%</td>
			<td style="width:89px;">Duke Scientific Corporation</td>
			<td style="width:119px;">3500A</td>
			<td></td>
		</tr>
		<tr height="57">
			<td height="57" style="height:57px;width:216px;">argon</td>
			<td style="width:89px;">Koike Sanso Kogyo Co., Ltd.</td>
			<td style="width:119px;"></td>
			<td>purity &#62; 99.999 vol.%</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:216px;"></td>
			<td style="width:89px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="57">
			<td height="57" style="height:57px;width:216px;">cavity slide</td>
			<td style="width:89px;">Matsunami Glass Ind.,Ltd.</td>
			<td style="width:119px;">83-0336</td>
			<td></td>
		</tr>
		<tr height="57">
			<td height="57" style="height:57px;width:216px;">inverted microscope</td>
			<td style="width:89px;">Nikon Instech Co., Ltd.</td>
			<td style="width:119px;">ECLIPSE Ti-U</td>
			<td></td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:216px;">Thermo Plate</td>
			<td style="width:89px;">Tokai Hit CO.,Ltd</td>
			<td style="width:119px;">TP-108R-C</td>
			<td></td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:216px;">Ar-Kr ion laser</td>
			<td style="width:89px;">Spectra-Physics</td>
			<td style="width:119px;">Stabilite 2018</td>
			<td></td>
		</tr>
		<tr height="57">
			<td height="57" style="height:57px;width:216px;">avalanche photodiode</td>
			<td style="width:89px;">ALV-GmbH</td>
			<td style="width:119px;">ALV-High Q.E. Avalanche Photo Diode</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:216px;">correlator</td>
			<td style="width:89px;">ALV-GmbH</td>
			<td style="width:119px;">ALV-5000/EPP</td>
			<td></td>
		</tr>
	</tbody>
</table>

measurement of particle size distribution in turbid solutions by dynamic light scattering microscopy

A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a technique used to measure the size distribution of polymer solutions or colloidal particles. Although this technique is widely used for the assessment of polymer solutions, it is difficult to measure the particle size in concentrated solutions due to the multiple scattering effect or strong light absorption. Therefore, the concentrated solutions should be diluted before measurement. Implementation of the confocal optical component in a dynamic light scattering microscope1 helps to overcome this barrier. Using such a microscopic system, both transparent and turbid systems can be analyzed under the same experimental setup without a dilution. As a representative example, a size distribution measurement of a temperature-responsive polymer solution was performed. The sizes of the polymer chains in an aqueous solution were several tens of nanometers at a temperature below the lower critical solution temperature (LCST). In contrast, the sizes increased to more than 1.0 &#181;m when above the LCST. This result is consistent with the observation that the solution turned turbid above the LCST.

在不同的焦点进行测定，示于图2（a）：为聚苯乙烯胶乳悬浮液散射光强度的时间相关函数（50纳米粒子半径）。这些相关的功能被转换成由逆拉普拉斯变换的流体力学半径的分布函数（参照图2（b）和（c）项 ）。采用相同的步骤，在25℃下分别得到的PNIPA溶液的流体动力学半径的时间相关函数和分发功能和35℃。 图3（a）和（b）示出的散射光强度的时间相关函数和下面的PNIPA溶液（25℃）和上述（35℃）的LCST的相应尺寸分布函数。大小分布函数是由逆拉普拉斯变换之后所获得的偏差校正。低于LCST的平均流体动力学半径为几十纳米，这是典型的聚合物溶液。与此相反，在高于LCST的流体动力学半径为约1.0微米。这一结果与以下事实的溶液是高于LCST混浊一致。红色和蓝色线条图3表示后立即得到的，该溶液后20分钟分别变为混浊，PNIPA溶液的粒度分布。 如图3（b）清楚地表明，聚集的生长。 <img alt="图1" src="/files/ftp_upload/54885/54885fig1.jpg" /> 图1.动态光散射显微镜的示意图。针孔（PH），光束分离器（BS），偏振器（POL）和雪崩光电二极管（APD）。 <a href="http://ecsource.jove.com/files/ftp_upload/54885/54885fig1large.jpg" target="_blank">请点击这里查看</a>一个更大的版本这个数字。 <img alt="图2" src="/files/ftp_upload/54885/54885fig2.jpg" /> 图2.为聚苯乙烯胶乳悬浮液的代表性结果。 （a）用于在聚苯乙烯胶乳悬浮液中的散射光强度的时间相关函数。标称半径为50nm，浓度为0.1％（重量）。两个数据集分别从不同的散射点获得。 （ 二 ），（ 三 ）相应大小分布为聚苯乙烯胶乳悬浮液的逆拉普拉斯变换获得的功能（一个）。红线对应的时间相关函数的初始振幅是约1.0，和蓝线对应于一个初始幅值即约0.2。横轴没有（B）和（c）考虑部分外差（PHD）的影响，计算的时候A &lt;&lt;<html> ; 1. <a href="http://ecsource.jove.com/files/ftp_upload/54885/54885fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图3" src="/files/ftp_upload/54885/54885fig3.jpg" /> 图3为一个PNIPA溶液代表性的结果。 （a）用于所述PNIPA溶液散射光强度的时间相关函数。 （b）在通过（a）的逆拉普拉斯变换获得的PNIPA溶液通讯尺寸分布函数。横轴计算考虑局部外差的每个数据集的效果。黑线表示在25℃下获得的数据。红线代表刚后溶液变混浊而获得的数据（35℃）。蓝线代表红色线的20分钟测量后获得的数据。/54885/54885fig3large.jpg“目标=”_空白“&gt;点击此处查看该图的放大版本。

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Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

一种用于使用动态光散射显微镜浓缩溶液的粒度分布的直接测量协议提出。

通过动态光散射显微镜混浊解决方案粒度分布的测定

A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a ...

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14.0K 次观看.  University of Tokyo. 一种用于使用动态光散射显微镜浓缩溶液的粒度分布的直接测量协议提出。 

视频: Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

Quantitative and Qualitative Examination of Particle-particle Interactions Using Colloidal Probe Nanoscopy

Colloidal Probe Nanoscopy (CPN), the study of the nano-scale interactive forces between a specifically prepared colloidal probe and any chosen substrate using the Atomic Force Microscope (AFM), can provide key insights into physical interactions present within colloidal systems. Colloidal systems are widely existent in several applications including, pharmaceuticals, foods, paints, paper, soil and minerals, detergents, printing and much more.1-3 Furthermore, colloids can exist in many states such as emulsions, foams and suspensions. Using colloidal probe nanoscopy one can obtain key information on the adhesive properties, binding energies and even gain insight into the physical stability and coagulation kinetics of the colloids present within. Additionally, colloidal probe nanoscopy can be used with biological cells to aid in drug discovery and formulation development. In this paper we describe a method for conducting colloidal probe nanoscopy, discuss key factors that are important to consider during the measurement, and show that both quantitative and qualitative data that can be obtained from such measurements.

Colloidal probe nanoscopy can be used within a variety of fields to gain insight into the physical stability and coagulation kinetics of colloidal systems and aid in drug discovery and formulation sciences using biological systems. The method described within provides a quantitative and qualitative means to study such systems.

粒子粒子相互作用采用胶体探针纳米显微定量和定性检查

Colloidal Probe Nanoscopy (CPN), the study of the nano-scale interactive forces between a specifically prepared colloidal probe and any chosen substrate ...

科研

化学

Dynamic Electrochemical Measurement of Chloride Ions

This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver chloride electrode is used extensively for potentiometric measurement of chloride ions concentration in electrolyte. In this measurement, long-term and continuous monitoring is limited due to the inherent drift and the requirement of a stable reference electrode. We utilized the chronopotentiometric approach to minimize drift and avoid the use of a conventional reference electrode. A galvanostatic pulse is applied to an Ag/AgCl electrode which initiates a faradic reaction depleting the Cl&#713; ions near the electrode surface. The transition time, which is the time to completely deplete the ions near the electrode surface, is a function of the ion concentration, given by the Nernst equation. The square root of the transition time is in linear relation to the chloride ion concentration. Drift of the response over two weeks is negligible (59 &#181;M/day) when measuring 1 mM [Cl&#713;]using a current pulse of 10 Am-2. This is a dynamic measurement where the moment of transition time determines the response and thus is independent of the absolute potential. Any metal wire can be used as a pseudo-reference electrode, making this approach feasible for long-term measurement inside concrete structures.

Dynamic measurement of chloride ions is presented. Transition time of an Ag/AgCl electrode, during a chronopotentiometric technique, can give the concentration of chloride ions in electrolyte. This method does not require a stable conventional reference electrode.

氯离子的动态电化学测试

This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver ...

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR

The main limitation of NMR-based investigations is low sensitivity. This prompts for long acquisition times, thus preventing real-time NMR measurements of metabolic transformations. Hyperpolarization via dissolution DNP circumvents part of the sensitivity issues thanks to the large out-of-equilibrium nuclear magnetization stemming from the electron-to-nucleus spin polarization transfer. The high NMR signal obtained can be used to monitor chemical reactions in real time. The downside of hyperpolarized NMR resides in the limited time window available for signal acquisition, which is usually on the order of the nuclear spin longitudinal relaxation time constant, T1, or, in favorable cases, on the order of the relaxation time constant associated with the singlet-state of coupled nuclei, TLLS. Cellular uptake of endogenous molecules and metabolic rates can provide essential information on tumor development and drug response. Numerous previous hyperpolarized NMR studies have demonstrated the relevancy of pyruvate as a metabolic substrate for monitoring enzymatic activity in vivo. This work provides a detailed description of the experimental setup and methods required for the study of enzymatic reactions, in particular the pyruvate-to-lactate conversion rate in presence of lactate dehydrogenase (LDH), by hyperpolarized NMR.

The sensitivity enhancement provided by dissolution dynamic nuclear polarization (DNP) enables following metabolic processes in real time by NMR and MRI. The characteristics and performances of a dedicated dissolution DNP setup designed for study enzymatic reactions are discussed.

溶出动态核极化仪器用NMR实时酶反应速率测量

The main limitation of NMR-based investigations is low sensitivity. This prompts for long acquisition times, thus preventing real-time NMR measurements of ...

A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) hydrogen fuel cells. Researchers seeking to develop such systems require a method of measuring the generated hydrogen. Herein, we describe a simple, low-cost, and robust method to measure the hydrogen generated from the reaction of solids with aqueous solutions. The reactions are conducted in a conventional one-necked round-bottomed flask placed in a temperature controlled water bath. The hydrogen generated from the reaction in the flask is channeled through tubing into a water-filled inverted measuring cylinder. The water displaced from the measuring cylinder by the incoming gas is diverted into a beaker on a balance. The balance is connected to a computer, and the change in the mass reading of the balance over time is recorded using data collection and spreadsheet software programs. The data can then be approximately corrected for water vapor using the method described herein, and parameters such as the total hydrogen yield, the hydrogen generation rate, and the induction period can also be deduced. The size of the measuring cylinder and the resolution of the balance can be changed to adapt the setup to different hydrogen volumes and flow rates.

The study of methods to generate on-demand hydrogen for fuel cells continues to grow in importance. However, systems to measure hydrogen evolution from the reaction of chemicals with water can be complicated and expensive. This article details a simple, low-cost, and robust method to measure the evolution of hydrogen gas.

一种简单，低成本和强大的系统来测量氢气与水溶液化学反应放出的音量

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) ...

Fabrication and Testing of Photonic Thermometers

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being leveraged for developing sophisticated photonic sensors. Silicon photonic sensors seek to exploit the strong confinement of light in nano-waveguides to transduce changes in physical state to changes in resonance frequency. In the case of thermometry, the thermo-optic coefficient, i.e., changes in refractive index due to temperature, causes the resonant frequency of the photonic device such as a Bragg grating to drift with temperature. We are developing a suite of photonic devices that leverage recent advances in telecom compatible light sources to fabricate cost-effective photonic temperature sensors, which can be deployed in a wide variety of settings ranging from controlled laboratory conditions, to the noisy environment of a factory floor or a residence. In this manuscript, we detail our protocol for the fabrication and testing of photonic thermometers.

We describe the process of fabrication and testing of photonic thermometers.

光子温度计的制作与测试

In recent years, a push for developing novel silicon photonic devices for telecommunications has generated a vast knowledge base that is now being ...

Nanosponge Tunability in Size and Crosslinking Density

We describe a protocol for the synthesis of linear polyesters containing pendant epoxide functionality and their incorporation into a nanosponge with controlled dimensions. This approach begins with synthesis of a functionalized lactone which is key to the pendant functionalization of the resulting polymer. Valerolactone (VL) and allyl-valerolactone (AVL) are then copolymerized using ring-opening polymerization. Post-polymerization modification is then used to install an epoxide moiety on some or all of the pendant allyl groups. Epoxy-amine chemistry is employed to form nanoparticles in a dilute solution of both polymer and small molecule diamine crosslinker based on the desired nanosponge size and crosslinking density. Nanosponge sizes can be characterized by transmission electron microscopy (TEM) imaging to determine the dimension and distribution. This method provides a pathway by which highly tunable polyesters can create tunable nanoparticles, which can be used for small molecule drug encapsulation. Due to the nature of the backbone, these particles are hydrolytically and enzymatically degradable for a controlled release of a wide range of hydrophobic small molecules.

This article describes a process for tuning the size and crosslinking density of covalently crosslinked nanoparticles from linear polyesters containing pendant functionality. By tailoring synthesis parameters (polymer molecular weight, pendant functionality incorporation, and crosslinker equivalents), a desired nanoparticle size and crosslinking density can be achieved for drug delivery applications.

Nanosponge 可调大小和交联密度

We describe a protocol for the synthesis of linear polyesters containing pendant epoxide functionality and their incorporation into a nanosponge with ...

DNA-magnetic Particle Binding Analysis by Dynamic and Electrophoretic Light Scattering

Isolation of DNA using magnetic particles is a field of high importance in biotechnology and molecular biology research. This protocol describes the evaluation of DNA-magnetic particles binding via dynamic light scattering (DLS) and electrophoretic light scattering (ELS). Analysis by DLS provides valuable information on the physicochemical properties of particles including particle size, polydispersity, and zeta potential. The latter describes the surface charge of the particle which plays major role in electrostatic binding of materials such as DNA. Here, a comparative analysis exploits three chemical modifications of nanoparticles and microparticles and their effects on DNA binding and elution. Chemical modifications by branched polyethylenimine, tetraethyl orthosilicate and (3-aminopropyl)triethoxysilane are investigated. Since DNA exhibits a negative charge, it is expected that zeta potential of particle surface will decrease upon binding of DNA. Forming of clusters should also affect particle size. In order to investigate the efficiency of these particles in isolation and elution of DNA, the particles are mixed with DNA in low pH (~6), high ionic strength and dehydration environment. Particles are washed on magnet and then DNA is eluted by Tris-HCl buffer (pH = 8). DNA copy number is estimated using quantitative polymerase chain reaction (PCR). Zeta potential, particle size, polydispersity and quantitative PCR data are evaluated and compared. DLS is an insightful and supporting method of analysis that adds a new perspective to the process of screening of particles for DNA isolation.

This protocol describes the synthesis of magnetic particles and evaluation of their DNA-binding properties via dynamic and electrophoretic light scattering. This method focuses on monitoring changes in particle size, their polydispersity and zeta potential of particle surface which play major role in binding of materials such as DNA.

动态和电泳光散射的 DNA-磁性颗粒结合分析

Isolation of DNA using magnetic particles is a field of high importance in biotechnology and molecular biology research. This protocol describes the ...

Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography

This protocol describes fabricating microfluidic devices with low X-ray background optimized for goniometer based fixed target serial crystallography. The devices are patterned from epoxy glue using soft lithography and are suitable for in situ X-ray diffraction experiments at room temperature. The sample wells are lidded on both sides with polymeric polyimide foil windows that allow diffraction data collection with low X-ray background. This fabrication method is undemanding and inexpensive. After the sourcing of a SU-8 master wafer, all fabrication can be completed outside of a cleanroom in a typical research lab environment. The chip design and fabrication protocol utilize capillary valving to microfluidically split an aqueous reaction into defined nanoliter sized droplets. This loading mechanism avoids the sample loss from channel dead-volume and can easily be performed manually without using pumps or other equipment for fluid actuation. We describe how isolated nanoliter sized drops of protein solution can be monitored in situ by dynamic light scattering to control protein crystal nucleation and growth. After suitable crystals are grown, complete X-ray diffraction datasets can be collected using goniometer based in situ fixed target serial X-ray crystallography at room temperature. The protocol provides custom scripts to process diffraction datasets using a suite of software tools to solve and refine the protein crystal structure. This approach avoids the artefacts possibly induced during cryo-preservation or manual crystal handling in conventional crystallography experiments. We present and compare three protein structures that were solved using small crystals with dimensions of approximately 10-20 &#181;m grown in chip. By crystallizing and diffracting in situ, handling and hence mechanical disturbances of fragile crystals is minimized. The protocol details how to fabricate a custom X-ray transparent microfluidic chip suitable for in situ serial crystallography. As almost every crystal can be used for diffraction data collection, these microfluidic chips are a very efficient crystal delivery method.

Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography

This protocol describes in detail how to fabricate and operate microfluidic devices for X-ray diffraction data collection at room temperature. Additionally, it describes how to monitor protein crystallization by dynamic light scattering and how to process and analyze obtained diffraction data.

用于原位晶体 x 射线衍射和原位的微流控芯片系列晶体学的动态光散射

This protocol describes fabricating microfluidic devices with low X-ray background optimized for goniometer based fixed target serial crystallography. The ...

Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid based on volatile solar and wind sources. The pressing demand of developing high-performance electrochemical energy storage solutions, i.e., batteries, relies on both fundamental understanding and practical developments from both the academy and industry. The formidable challenge of developing successful battery technology stems from the different requirements for different energy-storage applications. Energy density, power, stability, safety, and cost parameters all have to be balanced in batteries to meet the requirements of different applications. Therefore, multiple battery technologies based on different materials and mechanisms need to be developed and optimized. Incisive tools that could directly probe the chemical reactions in various battery materials are becoming critical to advance the field beyond its conventional trial-and-error approach. Here, we present detailed protocols for soft X-ray absorption spectroscopy (sXAS), soft X-ray emission spectroscopy (sXES), and resonant inelastic X-ray scattering (RIXS) experiments, which are inherently elemental-sensitive probes of the transition-metal 3d and anion 2p states in battery compounds. We provide the details on the experimental techniques and demonstrations revealing the key chemical states in battery materials through these soft X-ray spectroscopy techniques.

Here, we present a protocol for typical experiments of soft X-ray absorption spectroscopy (sXAS) and resonant inelastic X-ray scattering (RIXS) with applications in battery material studies.

软 x 射线吸收光谱和共振非弹性 x 射线散射法检测电池化学成分的元素敏感度

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid ...

Application of Voltage in Dynamic Light Scattering Particle Size Analysis

Dynamic light scattering (DLS) is a common method for characterizing the size distribution of polymers, proteins, and other nano- and microparticles. Modern instrumentation permits measurement of particle size as a function of time and/or temperature, but currently there is no simple method for performing DLS particle size distribution measurements in the presence of applied voltage. The ability to perform such measurements would be useful in the development of electroactive, stimuli-responsive polymers for applications such as sensing, soft robotics, and energy storage. Here, a technique using applied voltage coupled with DLS and a temperature ramp to observe changes in aggregation and particle size in thermoresponsive polymers with and without electroactive monomers is presented. The changes in aggregation behavior observed in these experiments were only possible through the combined application of voltage and temperature control. To obtain these results, a potentiostat was connected to a modified cuvette in order to apply voltage to a solution. Changes in polymer particle size were monitored using DLS in the presence of constant voltage. Simultaneously, current data were produced, which could be compared with particle size data, to understand the relationship between current and particle behavior. The polymer poly(N-isopropylacrylamide) (pNIPAM) served as a test polymer for this technique, as pNIPAM's response to temperature is well-studied. Changes in the lower-critical solution temperature (LCST) aggregation behavior of pNIPAM and poly(N-isopropylacrylamide)-block-poly(ferrocenylmethyl methacrylate), an electrochemically active block-copolymer, in the presence of applied voltage are observed. Understanding the mechanisms behind such changes will be important when trying to achieve reversible polymer structures in the presence of applied voltage.

Here, a protocol to apply voltage to solution during dynamic light scattering particle size measurements with the intent to explore the effect of voltage and temperature changes on polymer aggregation is presented.

电压在动态光散射粒子尺寸分析中的应用

Dynamic light scattering (DLS) is a common method for characterizing the size distribution of polymers, proteins, and other nano- and microparticles. ...