The authors gratefully acknowledge financial support from the Belgian Federal government (Belspo through the IAP VI/27 and IAP-7/05 programs), the European Union's Seventh Framework Programme (FP7/2007-2013 under grant agreement no. 310651 SACS), the Flemish government in the form of long-term structural funding "Methusalem" grant METH/08/04 CASAS, the "Strategisch Initiatief Materialen" SoPPoM program, and the Fund for Scientific Research Flanders (FWO) grant G.0349.12. W.B. gratefully acknowledge the chemistry department of the KU Leuven for a FLOF-scholarship. The authors thank UOP Antwerp for the kind donation of zeolite samples and the mechanical workshop of the KU Leuven for helping with the design and construction of the heating/vacuum cell used in this study.

注意事项:本报告中所使用的化学品和试剂采用相应的安全保护措施（实验服，手套，护目镜，通风柜）谨慎处理。本研究使用的微孔无机材料（具有尺寸范围从1至5微米的沸石），因此特殊的注意力引导到使用适当的灰尘保护（防尘口罩）的操作涉及。我们建议采用适当操作和/或废物处置前，在这项工作中所使用的化学品和试剂的相关材料安全数据（MSDS）的咨询。 1.沸石前处理<ol><li>热预处理 注意:使用除去杂质，如有机杂质之前，预先处理沸石材料，这可能会阻碍银簇的形成和发光。 <ol><li>称取克工业LTA（Na）的沸石（LTA商业沸石含有钠作为其框架抗衡离子）与帝宝坐在均匀它瓷托盘。 </li><li>使用的具有1小时的间隔5℃/分钟的温度变化速率在80℃和110℃，以避免沸石结构破坏在450℃下过夜加热沸石粉末在马弗炉。 </li><li>从烘箱中取出的沸石材料，让它冷却到室温环境条件下。 </li></ol></li><li>沸石颗粒的尺寸选择 注意:这将产生的起始沸石材料的更均匀的粒度分布，创造必要的均匀的薄膜。这一步也消除大量无定形颗粒，这往往是存在于工业生产的沸石。 <ol><li>称取g市售的LTA（Na）的，并将其悬浮到1升的去离子水。 </li><li>超声处理该悬浮液1小时，剧烈摇动该悬浮液用手工每隔10分钟。 </li><li>倒入悬浮液成液塑筒（1L）30分钟。颗粒小于10微米的尺寸留在悬浮液中，但较大的颗粒沉淀。 </li><li>倒出该悬浮液，并使用布氏漏斗通过过滤回收该粉末。用去离子水洗涤回收的粉三次。 </li><li>如在步骤1.1.2中所述的热治疗的粉末。 </li></ol></li></ol> 2.发光LTA（娜） - 银沸石复合材料的制备<ol><li>发光性银的合成交换LTA沸石[LTA（钠）-Ag]作为参考材料<ol><li>溶解在200毫升中的250毫升的高密度聚丙烯（HDPE）瓶的去离子水74.8毫克硝酸银。 </li><li>称重1克预处理LTA（Na）的样品，并在硝酸银溶液挂起。 </li><li>离开的HDPE瓶中搅拌过夜到室温的最终过端摇床烘箱。 </li><li>过滤用布氏漏斗的悬浮液并用去离子水洗涤沸石粉末3次。 </li><li>热回收的粉末在45马弗炉0℃下，使用如在步骤1.1.2中描述的相同的过程。 </li><li>冷却样品，并放置在具有受控湿度（98％相对湿度）的干燥器。通过将干燥器内的饱和硫酸钾溶液控制相对湿度15 </li><li>使用荧光分光光度计以及其外部量子效率测量样品的激发和发射光谱（在不同的波长）。 <ol><li>通过将样品在1毫米路径石英比色皿测量二维激发发光图。收集开始上述激发波长可达使用5纳米的步骤和0.1秒的驻留时间800纳米30纳米的发射光谱。 </li><li>申请使用用于灯强度和波长相关的检测的发射路径的原始数据的仪器软件校正。此外，使用长通滤波器，以避免在两维曲线二阶峰。 </li><li>执行量子efficiency测量通过使用附连到分光光度计的积分球16记录的发射扫描从240纳米到两种沸石样品和硫酸钡600纳米使用4-参考260nm处作为激发波长，然后计算使用仪器的软件的量子效率。 </li></ol></li></ol></li></ol> 3.发光[LTA（李） - 银]沸石复合材料的制备<ol><li>部分交换锂LTA沸石的合成LTA（李） 注:遵循的程序部分交换LTA（李）沸石由Yahiro和合作者报告被改编的制造17。 <ol><li>溶解在2.5L去离子水中17.2克硝酸锂。 </li><li>倾0.5升的硝酸锂溶液加入到1升的HDPE瓶中。 </li><li>称重3G-预处理LTA（Na）的沸石，然后在包含硝酸锂溶液中的高密度聚乙烯瓶中挂起。 </li><li>使用结束-O搅动烧瓶在室温下过夜VER-端摇床烘箱。 </li><li>过滤用布氏漏斗的悬浮液并用去离子水洗涤所回收的粉末3次。 </li><li>执行锂交换<ol><li>加0.5升的新鲜硝酸锂溶液（3.1.1），以含有从过滤步骤（3.1.5）将回收的粉末的1升的HDPE瓶中。 </li><li>重复步骤3.1.4和3.1.5。 </li><li>重复步骤3.1.6.1和3.1.6.2另外4倍。 </li></ol></li><li>回收的沸石粉末，并使用与1小时的间隔5℃/分钟的温度变化速率在80℃和110℃下过夜它加热在450℃的马弗炉。 </li></ol></li><li>发光的合成LTA（李） - 银]沸石<ol><li>溶解在200毫升用250毫升的HDPE瓶的去离子水74.8毫克硝酸银。 </li><li>权衡部分交换锂的LTA沸石[LTA（李）〕1克，并在硝酸银溶液（3.2.1）挂起。 </li><li>搅动HDPE FL问使用在室温下的最终过端摇床烘箱中过夜。 </li><li>过滤用布氏漏斗的悬浮液并用去离子水洗涤回收的沸石粉末3次。 </li><li>在马弗炉中在450℃下使用的用1小时的时间间隔5℃/分钟的温度变化速率在80℃和110℃下过夜加热处理的粉末。 </li><li>使用含有内（98％相对湿度）的饱和硫酸钾溶液在干燥器受控湿度条件下冷却样品。15 </li><li>测量以下步骤2.1.7中描述的方法的样品的激发和发射光谱，以及其外部量子效率。 </li><li>进行热重分析（TGA）来确定在不同温度下的样品中的水含量。1简言之，将30至50mg的所制备样品的在铂样品支架和它装入TGA设备中。测量从50重量损失℃，直至600℃用氮气流（90毫升/分钟）下以5℃/分钟的加热速率。 </li></ol></li></ol> 4.制作一个LTA（李） - 银/聚乙烯亚胺（PEI）复合镀膜的湿度传感应用注:本报告中使用的沉积过程进行了修改，并从18参考改编。 <ol><li> LTA（李） - 银胶体悬浮液的准备。 <ol><li>稀释1ml所商用50重量％PEI溶液至100毫升的去离子水。 </li><li>称取250毫克发光LTA（李） - 银材料。 </li><li>混合沸石和PEI解决方案一起125毫升的HDPE瓶并剧烈摇晃暂停。 </li><li>放置在一个40千赫超声波仪浴中的瓶中于室温下过夜，以获得均匀的悬浮液。 </li><li>倒入LTA（李） - 银/ PEI悬挂成一个喷雾瓶。 </li></ol></li><li>一个LTA（李） - 银/ PEI薄膜沉积到传感器PROT石英板otype生产。 <ol><li>通过用离子交换水和丙酮漂洗它连续，膜沉积之前清洁的石英板。干燥烘箱中的清洁板，在80℃1小时。 </li><li>喷雾涂布在石英板的一侧，通过从约20厘米的距离水平地放置在石英板在铝箔的一个清洁片和喷涂三次（3秒每时间）。放置一个干燥箱内的涂覆板在50℃下30分钟。 </li><li>重复步骤4.2.2另外4次直到薄膜是均匀的。 </li></ol></li><li>水化/脱水传感器原型。 <ol><li>放置石英涂层板进入一个内部的加热/真空室的样品室。5 </li><li>通过在涂板的顶部放置一个清洁石英板中结合有橡胶环关闭细胞的样品室和密封使用特氟隆塞和螺钉的小区， 如图2中所描绘。 </li><li>应用高真空，我们为了ING低于10 -3毫巴的压力，向细胞过夜以脱水样品。 </li><li>通过使用紫外灯在视觉上监视沉积膜的发射颜色的变化（在可见光区）。 </li><li>打开样品室来监测的发光颜色的变化，在可见光区域，在使用时的UV灯膜的补液。 </li><li>从步骤4.3.2开始周期多次重复4.3.5测试LTA（李） - 银/ PEI薄膜的可逆性。 </li></ol></li></ol>

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The authors have nothing to disclose.

A simple device to demonstrate the proof of concept of using LTA(Li)-Ag as a luminescence based humidity sensor was produced by spray coating the LTA(Li)-Ag powder suspended in a PEI solution onto a quartz plate. The PEI solution produces a polymer layer with homogenous thickness when the water is evaporated. The polymer-zeolite composite layer displays similar luminescent properties as that of the zeolite in powder form. The PEI/LTA(Li)-Ag zeolite composite displays the expected water-responsive luminescent properties, whose emission color changes upon variations in the water content present in the composite at relatively low humidity scale. 
Replacing Na with Li ions in LTA zeolites (calculated exchange rate 33%) has a notable impact on the self-assembly and stabilization of luminescent silver clusters in the LTA(Li) scaffolds leading to unique optical properties. The EQE of LTA(Li)-Ag as compared to LTA(Na)-Ag samples is enhanced by more than one order of magnitude. Moreover, the emission colors displayed by the LTA(Li)-Ag samples have a water-dependence, providing a potential application of the samples as luminescence based humidity sensors. 
We have thus demonstrated an easy method to fabricate a luminescent film-like humidity sensor through which changes in hydration levels can be visually monitored simply by using a UV lamp. The availability of the raw materials, the direct visualization of the color changes correlated with humidity content, the photo-stability of the films, and the relative ease of fabricating cost-effective devices make these luminescent materials potential candidates to compete with state-of-the-art humidity sensors based upon electrical responses. The procedure described in this report could also be applied and extended to different substrates, at different micro and macro scales, to make the sensor more flexible. Additionally, several critical steps during the fabrication of Ag-zeolites, which play an important role in determining the final optical properties of such materials, were discussed in this protocol. For instance, the pre-cleaning of the raw zeolite material leads to the removal of optical and chemical impurities, as well as to homogenous zeolite crystal size distribution. This is crucial for the incorporation of zeolites into functional devices. One limitation of the present methodology is the restriction on the use of thin film sensors beyond 75 &#176;C. This is mainly due to the decomposition of the PEI polymer, rather than to the degradation of the LTA(Li)-Ag zeolites, which can withstand up to 500 &#176;C. The use of heat-resistant polymers, such as polyvinyl alcohol, could expand the temperature range up to 200 &#176;C. We expect that further investigations will be directed to the development of methodologies for the synthesis of nanostructured Ag-zeolite composites with (multi)functional properties and finally to the design of advanced sensor prototypes.

通过自组装在密闭沸石基质形成小亚纳米oligoatomic银团簇显示独特的光学性质。1-5这种银沸石复合材料具有高的化学和光学稳定性。然而，它们的光致发光特性是高度依赖于银簇的局部环境。在银 - 沸石复合影响光学特性的环境条件，可分为内在和外在属性。内在特性都涉及到沸石拓扑，抗衡离子的类型和银负载1。另一方面，外在属性关联到合成后的变化，如吸附或水分子的存在沸石空腔。3,4-后者属性赋予对银-沸石复合，以光学地对外部刺激，例如在沸石骨架6-8内的水分的变化作出反应的能力</suP&gt;或确定气体的存在;因此它们的水蒸气和气体传感器的使用已被建议。9,10- 在最近的研究中，我们已经表明，银-沸石的湿气光学响应不仅相关，在其发射的吸收或骤冷的变化，但也对不同的发射颜色外观相对于它们的含水量。5的稳定化在部分锂交换的LTA沸石分别导致其改变在相对低湿度的比例反映在从蓝色动态颜色变化至绿色/黄色发射脱水和水合样品在透湿响应材料的形成中，银金属簇的。因此，使用这些材料作为基于发光的湿度传感器中提出的。迄今为止，不同类型的材料，如电解质，陶瓷，聚合物和纳米复合材料已经提出了用于在湿度b监控的变化ASED上电和光反应。11,12在此详细协议中，我们的目标是展示一个证明的概念为LTA（李）-Ag沸石的应用湿度传感器和用于进一步原型发展。由于LTA（李）-Ag沸石的通用性被纳入不同的衬底，其潜在的可扩展性和成本效益的制造，原型设计可能来促进。13这样的传感器可以具有在不同的工业部门，例如在潜在适用性农业，以及汽车和造纸工业。14

<table border="0" cellpadding="0" cellspacing="0" width="833">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:268px;">LTA(Na) zeolite</td>
			<td style="width:169px;">UOP</td>
			<td style="width:167px;">Molsiv adsorbent 4A</td>
			<td style="width:229px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Silver nitrate</td>
			<td>Sigma Aldrich</td>
			<td>209139</td>
			<td>&#8805;99,0%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Lithium nitrate</td>
			<td>Sigma Aldrich</td>
			<td>62574</td>
			<td>&#8805;99,0%, calc. on dry substances</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Polyethyleneimine solution</td>
			<td>Sigma Aldrich</td>
			<td>3880</td>
			<td>~50% H2O</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Scanning electron microscope (SEM)</td>
			<td>JEOL</td>
			<td>JSM-6010LV</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Thermogravimetric analyzer</td>
			<td>TA instruments</td>
			<td>Q500</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Spectrofluorimeter</td>
			<td>Edinburgh instruments</td>
			<td>FLS980-s</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Integrating sphere</td>
			<td>Labsphere</td>
			<td>4P-GPS-033-SL</td>
			<td></td>
		</tr>
	</tbody>
</table>

nanostructured ag-zeolite composites as luminescence-based humidity sensors

Small silver clusters confined inside zeolite matrices have recently emerged as a novel type of highly luminescent materials. Their emission has high external quantum efficiencies (EQE) and spans the whole visible spectrum. It has been recently reported that the UV excited luminescence of partially Li-exchanged sodium Linde type A zeolites [LTA(Na)] containing luminescent silver clusters can be controlled by adjusting the water content of the zeolite. These samples showed a dynamic change in their emission color from blue to green and yellow upon an increase of the hydration level of the zeolite, showing the great potential that these materials can have as luminescence-based humidity sensors at the macro and micro scale. Here, we describe the detailed procedure to fabricate a humidity sensor prototype using silver-exchanged zeolite composites. The sensor is produced by suspending the luminescent Ag-zeolites in an aqueous solution of polyethylenimine (PEI) to subsequently deposit a film of the material onto a quartz plate. The coated plate is subjected to several hydration/dehydration cycles to show the functionality of the sensing film.

在LTA银沸石的SEM显微照片的阳离子交换和热处理步骤之后进行记录。随后，光致发光的二维（2D）激发了两种水合LTA（Na）的-Ag及LTA（李）-Ag沸石（ 图1）的测量/发射曲线。用XPS对银交换的沸石，以确定它们的化学成分进行元素分析。分析表明，在LTA（Na）的和LTA（锂）的沸石的银交换非常接近与分别19.6％（重量）和21.5％（重量），银的重量百分比。在重量百分比的差异可以归因于锂原子的低级原子量。此外，元素分析还表明，锂交换后的Na的33％被替换。在样品上进行的阳离子交换和随后的热处理步骤似乎不影响LTA晶体的结构中，通过扫描电镜所证明。此外，较大的银N形成沸石晶体的表面上anoparticles没有可视化。发光特性在很大程度上他们的水合状态都LTA（李） - 银和LTA（娜） - 银样品之间的差异。通过将锂进入沸石框架作为抗衡阳离子，在激发最大值蓝移为LTA（Na）的-Ag及LTA（李）-Ag，分别发生从370纳米至260纳米。与此相反的最大发射经历了从550到565纳米的加入李进系统一个红色的小转变。这些样品之间的最大区别在其外部量子效率（EQE）被观察到。 LTA（钠）-Ag沸石具有约4％的EQE在其激发最大值（370纳米），而EQE为LTA（李）-Ag沸石达到62％（当在260nm激发）。这将导致一个明亮的黄色发光粉在254纳米的紫外线照射。 陆路交通管理局（李） - 银样品的发光性能还取决于的含水量系统。这是通过TGA和温度依赖的荧光实验的组合示出，TGA相关温度至沸石的水合程度。此外，温度为间接相关，通过使用一个内部的加热单元（ 图2）由LTA（李）-Ag样品显示的发光颜色。从黄色发光的颜色变化绿蓝，从LTA除水时，（李） - 银系统。该EQE稳步上升，从62％（水合状态）下降到21％（脱水状态）。 因为LTA（李）-Ag的水响应行为的，使用这种材料由粉末悬浮成PEI溶液以制造基于发光湿度传感器原型，随后喷雾复合涂覆到石英板。图像（在日光和紫外光照射）的喷涂LTA（李）-Ag / PEI薄膜和SEM显微照片显示在图3中 ，我们观察到，通过USI<html>纳克得到此涂布步骤，在发光方面具有聚合物 - 沸石复合的相对同质层。的SEM显微照片表明，该沸石晶体不是由涂覆程序改变。通过使用一个内部的加热/真空室也有人证明，聚合物 - 沸石膜保留哪些是在粉末形式的沸石所观察到的水响应性的特性。 <img alt="图1" src="/files/ftp_upload/54674/54674fig1.jpg" /> 图1:SEM 照片和银色的发光性能交换LTA沸石 SEM照片和LTA（娜） -银（A，B）和LTA（李） -银（C，D）的二维激发-发射图。在2D激发发光地块插图下不同的激发波长（254，300，366和450纳米）显示样品的模拟发射颜色。<html> OAD / 54674 / 54674fig1large.jpg"目标="_空白"&gt;点击此处查看该图的放大版本。 <img alt="图2" src="/files/ftp_upload/54674/54674fig2.jpg" /> 图2:LTA（李） -银的发光性能水化水平的影响。 。 一 ）在本研究中B）TGA积为LTA（李）的LTA（李） -银样品C）归一化发射光谱（260时nm激发）所采用的内部加热/真空室的示意图-银样品在不同温度下测得的。D）计划显示实际样品相对于含水量的发光颜色的变化。 <a href="http://ecsource.jove.com/files/ftp_upload/54674/54674fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> ftp_upload / 54674 / 54674fig3.jpg"/&gt; 图3: 基于一个LTA（李） -银/ PEI复合发光湿度传感器。 a）根据日光照明的涂板的照片。 （B，C）根据254nm的UV光照射的脱水和水合涂板，分别四 ）示出LTA（Li的分布）的石英表面上-Ag结晶沉积膜的SEM显微照片的照片。插图显示原始SEM显微照片。e）该水合和脱水的PEI / LTA（李）-Ag沸石复合，排放最大值10水合期间/使用260nm的作为激发波长。˚F脱水周期）的选定区域的放大剧情显示PEI / LTA（李）10水合/脱水循环后-Ag分子筛复合的最大发射剖面的行为。 <a href="http://ecsource.jove.com/files/ftp_upload/54674/54674fig3large.jpg" target="_blank">请点击此处为vi</a>EW这个数字的放大版本。

Watch this Scientific Journal Video about Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors at JoVE.com

Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors

A protocol for the synthesis of moisture-responsive luminescent Ag-zeolite composites is described in this report.

纳米银沸石复合材料作为基于发光的湿度传感器

Small silver clusters confined inside zeolite matrices have recently emerged as a novel type of highly luminescent materials. Their emission has high ...

nanostructured-ag-zeolite-composites-as-luminescence-based-humidity

Universidad de Cartagena UDEC

Research

JoVE Journal

Engineering

10.1K 次观看.  KU Leuven. A protocol for the synthesis of moisture-responsive luminescent Ag-zeolite composites is described in this report.

视频: Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors

Development of Whispering Gallery Mode Polymeric Micro-optical Electric Field Sensors

Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The optical modes are frequently referred to as "whispering gallery modes" (WGM) or "morphology dependent resonances" (MDR) and exhibit high optical quality factors. Some proposed applications of micro-cavity optical resonators are in spectroscopy1, micro-cavity laser technology2, optical communications3-6 as well as sensor technology. The WGM-based sensor applications include those in biology7, trace gas detection8, and impurity detection in liquids9. Mechanical sensors based on microsphere resonators have also been proposed, including those for force10,11, pressure12, acceleration13 and wall shear stress14. In the present, we demonstrate a WGM-based electric field sensor, which builds on our previous studies15,16. A candidate application of this sensor is in the detection of neuronal action potential.
The electric field sensor is based on polymeric multi-layered dielectric microspheres. The external electric field induces surface and body forces on the spheres (electrostriction effect) leading to elastic deformation. This change in the morphology of the spheres, leads to shifts in the WGM. The electric field-induced WGM shifts are interrogated by exciting the optical modes of the spheres by laser light. Light from a distributed feedback (DFB) laser (nominal wavelength of ~ 1.3 &mu;m) is side-coupled into the microspheres using a tapered section of a single mode optical fiber. The base material of the spheres is polydimethylsiloxane (PDMS). Three microsphere geometries are used: (1) PDMS sphere with a 60:1 volumetric ratio of base-to-curing agent mixture, (2) multi layer sphere with 60:1 PDMS core, in order to increase the dielectric constant of the sphere, a middle layer of 60:1 PDMS that is mixed with varying amounts (2% to 10% by volume) of barium titanate and an outer layer of 60:1 PDMS and (3) solid silica sphere coated with a thin layer of uncured PDMS base. In each type of sensor, laser light from the tapered fiber is coupled into the outermost layer that provides high optical quality factor WGM (Q ~ 106). The microspheres are poled for several hours at electric fields of ~ 1 MV/m to increase their sensitivity to electric field.

A high-sensitivity photonic micro sensor was developed for electric field detection. The sensor exploits the optical modes of a dielectric sphere. Changes in the external electric field perturb the sphere morphology leading to shifts in its optical modes. The electric field strength is measured by monitoring these optical shifts.

回音壁模式聚合物微光学电场传感器的发展

Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The ...

科研

工程学

A Testing Platform for Durability Studies of Polymers and Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Stimuli

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs and condition-based maintenance. These materials are adopted in a wide range of engineering applications, from aircraft and ship structures, to bridges, wind turbine blades, biomaterials and biomedical implants. Polymers are viscoelastic materials, and their response may be highly nonlinear and thus make it challenging to predict and monitor their in-service performance. The laboratory-scale testing platform presented herein assists the investigation of the influence of concurrent mechanical loadings and environmental conditions on these materials. The platform was designed to be low-cost and user-friendly. Its chemically resistant materials make the platform adaptable to studies of chemical degradation due to in-service exposure to fluids. An example of experiment was conducted at RT on closed-cell polyurethane foam samples loaded with a weight corresponding to ~50% of their ultimate static and dry load. Results show that the testing apparatus is appropriate for these studies. Results also highlight the larger vulnerability of the polymer under concurrent loading, based on the higher mid-point displacements and lower residual failure loads. Recommendations are made for additional improvements to the testing apparatus.

The durability of polymers and fiber-reinforced polymer composites in service is a critical aspect for their designs and condition-based maintenance. We present a novel low-cost laboratory testing platform for the investigation of the influence of concurrent mechanical and environmental loadings, and may help design more efficient yet safer composite structures.

一个测试平台为聚合物的耐久性研究，并在同期Hygrothermo机械刺激纤维增强聚合物复合材料

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs ...

Preparation and Reactivity of Gasless Nanostructured Energetic Materials

High-Energy Ball Milling (HEBM) is a ball milling process where a powder mixture placed in the ball mill is subjected to high-energy collisions from the balls. Among other applications, it is a versatile technique that allows for effective preparation of gasless reactive nanostructured materials with high energy density per volume (Ni+Al, Ta+C, Ti+C). The structural transformations of reactive media, which take place during HEBM, define the reaction mechanism in the produced energetic&#160;composites. Varying the processing conditions permits fine tuning of the milling-induced microstructures of the fabricated composite particles. In turn, the reactivity, i.e., self-ignition temperature, ignition delay time, as well as reaction kinetics, of high energy density materials depends on its microstructure. Analysis of the milling-induced microstructures suggests that the formation of fresh oxygen-free intimate high surface area contacts between the reagents is responsible for the enhancement of their reactivity. This manifests itself in a reduction of ignition temperature and delay time, an increased rate of chemical reaction, and an overall decrease of the effective activation energy of the reaction. The protocol provides a detailed description for the preparation of reactive nanocomposites with tailored microstructure using short-term HEBM method. It also describes a high-speed thermal imaging technique to determine the ignition/combustion characteristics of the energetic materials. The protocol can be adapted to preparation and characterization of a variety of nanostructured energetic composites.

This protocol describes the preparation of gasless nanostructured energetic materials (Ni+Al, Ta+C, Ti+C) using the short-term high-energy ball milling (HEBM) technique. It also describes a high-speed thermal imaging method to study the reactivity of mechanically fabricated nanocomposites. These protocols can be extended to other reactive nanostructured energetic materials.

准备和无气腹纳米结构的反应含能材料

High-Energy Ball Milling (HEBM) is a ball milling process where a powder mixture placed in the ball mill is subjected to high-energy collisions from the ...

Surface Enhanced Raman Spectroscopy Detection of Biomolecules Using EBL Fabricated Nanostructured Substrates

Fabrication and characterization of conjugate nano-biological systems interfacing metallic nanostructures on solid supports with immobilized biomolecules is reported. The entire sequence of relevant experimental steps is described, involving the fabrication of nanostructured substrates using electron beam lithography, immobilization of biomolecules on the substrates, and their characterization utilizing surface-enhanced Raman spectroscopy (SERS). Three different designs of nano-biological systems are employed, including protein A, glucose binding protein, and a dopamine binding DNA aptamer. In the latter two cases, the binding of respective ligands, D-glucose and dopamine, is also included. The three kinds of biomolecules are immobilized on nanostructured substrates by different methods, and the results of SERS imaging are reported. The capabilities of SERS to detect vibrational modes from surface-immobilized proteins, as well as to capture the protein-ligand and aptamer-ligand binding are demonstrated. The results also illustrate the influence of the surface nanostructure geometry, biomolecules immobilization strategy, Raman activity of the molecules and presence or absence of the ligand binding on the SERS spectra acquired.

We describe the fabrication and characterization of nano-biological systems interfacing nanostructured substrates with immobilized proteins and aptamers. The relevant experimental steps involving lithographic fabrication of nanostructured substrates, bio-functionalization, and surface-enhanced Raman spectroscopy (SERS) characterization, are reported. SERS detection of surface-immobilized proteins, and probing of protein-ligand and aptamer-ligand binding is demonstrated.

表面增强拉曼光谱检测生物分子利用EBL装配纳米衬底

Fabrication and characterization of conjugate nano-biological systems interfacing metallic nanostructures on solid supports with immobilized biomolecules ...

Preparation and Evaluation of Hybrid Composites of Chemical Fuel and Multi-walled Carbon Nanotubes in the Study of Thermopower Waves

When a chemical fuel at a certain position in a hybrid composite of the fuel and a micro/nanostructured material is ignited, chemical combustion occurs along the interface between the fuel and core materials. Simultaneously, dynamic changes in thermal and chemical potentials across the micro/nanostructured materials result in concomitant electrical energy generation induced by charge transfer in the form of a high-output voltage pulse. We demonstrate the entire procedure of a thermopower wave experiment, from synthesis to evaluation. Thermal chemical vapor deposition and the wet impregnation process are respectively employed for the synthesis of a multi-walled carbon nanotube array and a hybrid composite of picric acid/sodium azide/multi-walled carbon nanotubes. The prepared hybrid composites are used to fabricate a thermopower wave generator with connecting electrodes. The combustion of the hybrid composite is initiated by laser heating or Joule-heating, and the corresponding combustion propagation, direct electrical energy generation, and real-time temperature changes are measured using a high-speed microscopy system, an oscilloscope, and an optical pyrometer, respectively. Furthermore, the crucial strategies to be adopted in the synthesis of hybrid composite and initiation of their combustion that enhance the overall thermopower wave energy transfer are proposed.

A protocol for conducting thermopower wave experiments is presented. The synthesis of hybrid composites of a chemical fuel and micro/nanostructured material, manufacturing of a thermopower wave generator, and methods for measuring the corresponding physical phenomena are described.

化学燃料和多壁碳纳米管的混杂复合材料的热电波的研究准备和评估

When a chemical fuel at a certain position in a hybrid composite of the fuel and a micro/nanostructured material is ignited, chemical combustion occurs ...

Iridium Oxide-reduced Graphene Oxide Nanohybrid Thin Film Modified Screen-printed Electrodes as Disposable Electrochemical Paper Microfluidic pH Sensors

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use integrated paper microfluidic electrochemical pH sensor for resource-limited settings. Taking advantages from both pH meters and strips, the pH sensing platform is composed of hydrophobic barrier-patterned paper micropad (&#181;PAD) using polydimethylsiloxane (PDMS), screen-printed electrode (SPE) modified with IrO2-graphene films and molded acrylonitrile butadiene styrene (ABS) plastic holder. Repetitive cathodic potential cycling was employed for graphene oxide (GO) reduction which can completely remove electrochemically unstable oxygenated groups and generate a 2D defect-free homogeneous graphene thin film with excellent stability and electronic properties. A uniform and smooth IrO2 film in nanoscale grain size is anodically electrodeposited onto the graphene film, without any observable cracks. The resulting IrO2-RGO electrode showed slightly super-Nernstian responses from pH 2-12 in Britton-Robinson (B-R) buffers with good linearity, small hysteresis, low response time and reproducibility in different buffers, as well as low sensitivities to different interfering ionic species and dissolved oxygen. A simple portable digital pH meter is fabricated, whose signal is measured with a multimeter, using high input-impedance operational amplifier and consumer batteries. The pH values measured with the portable electrochemical paper-microfluidic pH sensors were consistent with those measured using a commercial laboratory pH meter with a glass electrode.

The study demonstrates the growth of iridium oxide-reduced graphene oxide (IrO2-RGO) nanohybrid thin films on irregular and rough screen-printed carbon substrate through a green electrochemical synthesis, and their implementation as a pH sensor with a patterned paper-fluidic platform.

氧化铱还原氧化石墨烯纳米杂化薄膜修饰丝网印刷电极一次性电化学微流控纸pH传感器

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use ...

Ultrasonic Welding of Thermoplastic Composite Coupons for Mechanical Characterization of Welded Joints through Single Lap Shear Testing

This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints.

A straightforward procedure for ultrasonic welding of thermoplastic composite coupons for basic mechanical testing is described. Key characteristics of this ultrasonic welding process are the use of flat energy directors for simplified process preparation and the use of process data for the fast definition of optimum processing conditions.

通过单搭接剪切试验的热塑性复合材料优惠券焊接接头的力学特性的超声波焊接

This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ...

Fiber Optic Distributed Sensors for High-resolution Temperature Field Mapping

The reliability of computational fluid dynamics (CFD) codes is checked by comparing simulations with experimental data. A typical data set consists chiefly of velocity and temperature readings, both ideally having high spatial and temporal resolution to facilitate rigorous code validation. While high resolution velocity data is readily obtained through optical measurement techniques such as particle image velocimetry, it has proven difficult to obtain temperature data with similar resolution. Traditional sensors such as thermocouples cannot fill this role, but the recent development of distributed sensing based on Rayleigh scattering and swept-wave interferometry offers resolution suitable for CFD code validation work. Thousands of temperature measurements can be generated along a single thin optical fiber at hundreds of Hertz. Sensors function over large temperature ranges and within opaque fluids where optical techniques are unsuitable. But this type of sensor is sensitive to strain and humidity as well as temperature and so accuracy is affected by handling, vibration, and shifts in relative humidity. Such behavior is quite unlike traditional sensors and so unconventional installation and operating procedures are necessary to ensure accurate measurements. This paper demonstrates implementation of a Rayleigh scattering-type distributed temperature sensor in a thermal mixing experiment involving two air jets at 25 and 45 &#176;C. We present criteria to guide selection of optical fiber for the sensor and describe installation setup for a jet mixing experiment. We illustrate sensor baselining, which links readings to an absolute temperature standard, and discuss practical issues such as errors due to flow-induced vibration. This material can aid those interested in temperature measurements having high data density and bandwidth for fluid dynamics experiments and similar applications. We highlight pitfalls specific to these sensors for consideration in experiment design and operation.

We demonstrate use of a fiber optic distributed sensor for mapping the temperature field of mixing air jets. The Rayleigh scattering-based sensor generates thousands of data points along a single fiber to provide exceptional spatial resolution that is unattainable with traditional sensors such as thermocouples.

对于高分辨率温度场测绘光纤分布式传感器

The reliability of computational fluid dynamics (CFD) codes is checked by comparing simulations with experimental data. A typical data set consists ...

Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise composition of these materials is essential, especially in the design of surface catalysts, where the surface concentration of the active component determines the activity of the material. Antimicrobial materials which utilize nanoparticles are a particular focus of this technology. Recently swell encapsulation has emerged as a technique for inserting antimicrobial nanoparticles into a host polymer matrix. Swell encapsulation provides the advantage of localizing the incorporation to the external surfaces of materials, which act as the active sites of these materials. However, quantification of this nanoparticle uptake is challenging. Previous studies explore the link between antimicrobial activity and surface concentration of the active component, but this is not directly visualized. Here we show a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of CdSe/ZnS nanoparticles can be accurately visualized through cross-sectional fluorescence imaging. Using this method, we can quantify the uptake of nanoparticles via swell encapsulation and measure the surface concentration of encapsulated particles, which is key in optimizing the activity of functional materials.

Here we present a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of cadmium selenide quantum dots can be accurately visualized through cross-sectional fluorescence imaging.

纳米粒子 - 聚合物复合材料使用直接荧光成像的先进成分分析

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise ...

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia (YSZ) Scaffolds by In Situ Carbon Templating Xerogels

We demonstrate a method for the high temperature fabrication of porous, nanostructured yttria-stabilized-zirconia (YSZ, 8 mol% yttria - 92 mol% zirconia) scaffolds with tunable specific surface areas up to 80 m2&#183;g-1. An aqueous solution of a zirconium salt, yttrium salt, and glucose is mixed with propylene oxide (PO) to form a gel. The gel is dried under ambient conditions to form a xerogel. The xerogel is pressed into pellets and then sintered in an argon atmosphere. During sintering, a YSZ ceramic phase forms and the organic components decompose, leaving behind amorphous carbon. The carbon formed in situ serves as a hard template, preserving a high surface area YSZ nanomorphology at sintering temperature. The carbon is subsequently removed by oxidation in air at low temperature, resulting in a porous, nanostructured YSZ scaffold. The concentration of the carbon template and the final scaffold surface area can be systematically tuned by varying the glucose concentration in the gel synthesis. The carbon template concentration was quantified using thermogravimetric analysis (TGA), the surface area and pore size distribution was determined by physical adsorption measurements, and the morphology was characterized using scanning electron microscopy (SEM). Phase purity and crystallite size was determined using X-ray diffraction (XRD). This fabrication approach provides a novel, flexible platform for realizing unprecedented scaffold surface areas and nanomorphologies for ceramic-based electrochemical energy conversion applications, e.g. solid oxide fuel cell (SOFC) electrodes.

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia YSZ Scaffolds by In Situ Carbon Templating Xerogels

A protocol for fabricating porous, nanostructured yttria-stabilized-zirconia (YSZ) scaffolds at temperatures between 1,000 &#176;C and 1,400 &#176;C is presented.

通过纳米氧化钇稳定的二氧化锆（YSZ）的支架的高温加工<em&gt;原位</em&gt;碳模板干凝胶

We demonstrate a method for the high temperature fabrication of porous, nanostructured yttria-stabilized-zirconia (YSZ, 8 mol% yttria - 92 mol% zirconia) ...