RJAH acknowledges support from EPSRC Fellowship EP/I004599/1, MMS acknowledges funding from EPSRC under grant number EP/K5035-4X/1.

注：实验装置在图示意性示出。 2。该装置的主要部分包括一个旋转平台英寸（300毫米×300 MM）安装在铜圆柱体（55毫米直径的），根据其自身重量下降到一个超导磁体（1.8 T）的强磁场与房间的温度的垂直钻孔。该平台是由通过离轴马达转动的滑动轴承带有一锁眼孔口旋转。铜柱附加到同时旋转，并且一旦所述保持针被移除下降一个钥匙形状的驱动轴。 1，非标设备的研制<ol><li>浮选船<ol><li>使船的尺寸，使得其舒适适合实验槽内而不触及两侧。 注：浮选船（ 见图3）由聚苯乙烯壁和海绵碱。 </li><li>保护海绵ST一层荣纸巾。 注：薄纸的目的是从注入船尽可能流体消散尽可能垂直动量。 </li></ol></li></ol> 2.实验准备<ol><li>液层的制备<ol><li>允许蒸馏水拿出到实验室温度（22±2℃）。大约650毫升需要对每个实验实现。 注：使混合物平衡防止形成气泡在实验中由于exsolving空气。 </li><li>分离蒸馏水入等体积在两个单独的容器中，A和B，这将被用于为密集下层和光上层分别制备的液体。 </li><li> 易地准备致密下层。集装箱A的内容： <ol><li>添加氯化钠达到0.43摩尔氯化钠的每升水的浓度为每升（约25克NaCl的水将需要）; </li><li>添加0.33克红色和蓝色的跟踪水基染料到下层的容器（ 例如 ，Cole-Parmer公司00295-16＆-18）; </li><li>加入0.1克L- -1荧光素钠。 注：下层将现在在外观不透明并具有约1012.9±1.2公斤米-3的密度。 </li></ol></li><li> 易地准备光上层。为了容器B的内容： <ol><li>加的MnCl 2盐以实现0.06摩尔的浓度的MnCl 2每升水（约12克的MnCl 2每升水）。 注：上层将在外观透明，具有大约998.2±0.5公斤米-3的密度。 </li></ol></li><li>以改变流体层的粘度，以等量添加甘油的 C 3 H 8 O 3到每一层所需的粘度直至达到。典型viscositie谎言范围1.00×10 -3 - 21.00×10 -3帕秒。各层的粘度是相同的。 注：混合物可安全地存储在其单独的容器中，直到需要。 </li><li> 易地准备密度分层的。 <ol><li>添加300毫升的容器A的内容到圆柱形内罐（参照图2）。 </li><li>从容器B内浸入液体中漂浮的船的海绵。 注：（2.1.6.2）的程序是时间敏感的经过，所以没有进行任何进一步的步骤，直到所有的磁铁，灯光，录音和机械机制已准备就绪。 </li><li>解除浮选船出容器的B，并且当它已经停止滴下，小心地将浮选船在稠密流体中的内圆柱罐中的层的顶部。 </li><li>开始从容器B向浮选小船的流速添加光层流体3毫升/分钟。作为浮选舟从两个层之间的界面升降机远逐渐增加该流速。保持该接口不被流体流的增加的动量的干扰，但足够快，该过程需要不超过20分钟的足够慢流速。保持填充直到上层中含有320毫升的流体。 注：下位层将设在约33毫米的深度，并且上层将在约39毫米的深度。 </li><li>小心地将有机玻璃盖到上层，使得每个层的层深度是相等的。允许流体和空气通过泄放孔流动，以确保没有空气的下方卡住。在有机玻璃盖顶部观察清光层液体层（约6毫米）。 注意：如果该过程已成功将有相等深度的液体两层在它们之间具有清晰的界面。扩散层的界面处的厚度将小于2μmm，在这个阶段。 </li></ol></li><li>有明确的蒸馏水外罐填充到一个高度内罐的有机玻璃盖体6毫米的位置。当观察方上会有从内筒罐所得无曲率引起的视差。 注意：由于在每一层中的液体被跨越接口在这点上连续地扩散，立即进行下面的步骤。 </li></ol></li><li>分层的自旋向上<ol><li>放置在平台上的实验罐。 </li><li>布置在磁体，通过在轨道和在位置上的保持销锁孔孔口驱动轴的孔中的铜圆柱体的位置。确保该罐是远（60厘米）从磁体使得在液体的磁力是在该位置可忽略不计。 注意：携带含有分层实验箱介绍一些困难;长，低振幅，晃动波建立与日走Ë坦克将腐烂了，有浮在上层实现时的界面质量的影响可以忽略。 </li><li>转动电机上，在0.002弧度小号-2增加旋转速度，旋转式的流体至所需旋转速率。对于16的旋转速率旋转加速时间为顺序20分钟- 60分钟。 注意：用最快的转速为13.2弧度秒-1。 </li></ol></li></ol> 3.实验执行<ol><li>确保磁铁指示1.2T的磁场强度，并且，在在该不稳定启动场梯度的高度为（毕业B 2）/ 2 = -14.3Ť2 M -1，其中B是磁感应。 </li><li>确保视频摄像机被布置为使得当该驱动轴是在它的最低位置或实验的侧面图是在焦点，或平面图处于对焦通过镜子复实验上述杆进洞。 </li><li>确保环境照明是在正确的水平，例如，没有通过摄像机拍摄的图像的饱和，而是充分反应时（灰度强度范围在0-255）。 </li><li>开始录像（240 FPS）。使用遥控器，以防止在操作记录功能移动相机。 </li><li>移除的保持销，允许罐下降，在旋转的同时，进入磁场。 </li></ol> 4.重置实验<ol><li>复位试验装置<ol><li>使用遥控器停止视频录制。 </li><li>保存电影文件到磁盘。 </li><li>用手，降低电压到电机，使得它减缓停顿。逐步执行此，以防止溢漏。 </li><li>从磁铁取出实验装置。 </li><li>适当的混合液体层处分（见锰四水氯化MSDS）。 </li><li>用水冲洗水箱（它并不需要进行蒸馏出），直到盐的所有痕迹已被冲走。避免与液体直接接触皮肤。 </li><li>用纸巾仔细擦干罐，以确保没有残余物留下可能污染后续实验。 </li></ol></li></ol> 5.图像处理<ol><li>提取每个动画帧的单个图像并保存无损.png格式。屏蔽掉每一帧的任何不需要的区域，例如在平台或铜圆柱体。 </li><li>使用离散快速傅立叶变换的不稳定性的开始之后计算2秒各图像帧的二维自相关函数16。记录的最小，平均，并在实验的旋转速度和流体层的粘度的观察波长的最大值。 </li></ol>

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作者什么都没有透露。

有该协议中的两个关键步骤。第一是2.1.6.4。如果光层的致密层上浮动过快，那么这两个混溶流体层的不可逆的混合发生。至关重要的是，这是避免与这两个层之间的尖锐（&lt;2mm）的接口的实现。第二个关键步骤是3.1.5。如果实验朝磁铁释放，而没有被完全纺成刚体旋转或不可视化和图像采集设备，位置和待命然后重复上述步骤（2.1.6）。 液体层的组成，磁场强度和电动机性?...

<html>包括两层的密度分层的流体系统可以在任一稳定的或不稳定的结构被布置在引力场。如果致密重层underlies密度较小，光层则系统是稳定的：扰动界面是稳定的，在重力作用下恢复，并且波可能的接口上被支持。如果重层覆盖的光层，然后系统是不稳定的和扰动的界面生长。这一基本的流体不稳定性是瑞利-泰勒不稳定性7,8。完全相同的不稳定性，可以在该朝向较重层加速非旋转系统中观察到。由于它在很多流动的规模也相差很大观察不稳定的根本性质：由小规模的薄膜现象9观察天体物理尺度特征，例如，蟹状星云EF“&gt; 10，其中观察到手指状结构，由脉冲星风创建正在通过密集的超新星遗迹加快。这是一个悬而未决的问题瑞利-泰勒不稳定性如何可以控制或影响，一旦最初的不稳定的密度差一直在界面处建立的。一种可能性是考虑系统的散装转动。该实验的目的是研究在系统上的旋转的作用，以及是否可能是稳定的路由。 我们认为由两个层重力不稳定层，是受围绕平行于重力方向的轴线转动平稳的流体系统。的扰动到不稳定两层密度分层导致斜压产生涡， 即 ，倾覆，在界面，趋于分手任何垂直结构。然而，旋转流体已知本身组织成相干垂直ST与旋转轴对齐ructures，所谓的“泰勒列”11。因此所研究的系统经受旋转的稳定效果之间的竞争，这是组织流入垂直结构并防止两层倾覆，和的致密流体的不稳定影响覆在界面产生一个翻转运动的打火机流体。具有增加的旋转速度的流体层的径向移动，以相反方向彼此以本身重新组合成一个更稳定的配置的能力，被越来越多地由泰勒普劳德曼定理12,13抑制：径向运动被减少而作为物化不稳定的发展所观察到的结构是规模较小。 图。 1所示定性旋转上形成作为不稳定拓漩涡的影响。在里面左手图像没有转动和流动是近似值经典非旋转瑞利 - 泰勒不稳定。在右手图像中的所有的实验参数是相同的，只是系统正在绕与油箱的中心对准的垂直轴线左侧的图像。它可以看出，旋转的作用是减小所形成的涡流的大小。这，反过来，将导致该比非旋转对应发展更缓慢的不稳定性。 该修改在流体中的应力张量的磁效应可以被视为以相同的方式作为修正重力场作用。因此，我们能够创造一个引力稳定层和自旋它变成固体旋转。通过施加梯度磁场产生的磁体积力则模仿修改引力场的效果。这使得该接口不稳定使得流体系统BEHAVES，以一个很好的近似，因为在旋转的古典瑞利 - 泰勒不稳定性。这种方法已被以前试图在两个维度不旋转14,15。用于与感应磁场B施加梯度磁场，施加恒定磁体积磁化率χ的流体的体积力为f =研究所（χB 2 /μ0），考虑到其中B = | C |和μ0 =4π×10 -7 NA -2是自由空间的磁导率。因此，我们可以考虑在磁铁来操作各个流体层，其中，每在强度克重力场密度ρ的流体的单位体积的有效重量用ρ 为g的有效重量- χ（∂B 2 /∂ž ）/（2μ0）。

<table border="0" cellpadding="0" cellspacing="0" width="696">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Blue water tracing dye</td>
			<td style="width:195px;">Cole-Parmer</td>
			<td style="width:119px;">00295-18</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Red water tracing dye</td>
			<td style="width:195px;">Cole-Parmer</td>
			<td style="width:119px;">00295-16</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium Chloride</td>
			<td style="width:195px;"></td>
			<td style="width:119px;"></td>
			<td>&#62;99% purity</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Manganese Chloride Tetrahydrate</td>
			<td style="width:195px;"></td>
			<td style="width:119px;"></td>
			<td>See MSDS</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fluorescein sodium salt&#160;</td>
			<td style="width:195px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Magnet</td>
			<td style="width:195px;">Cryogenic Ltd. London</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

magnetically induced rotating rayleigh-taylor instability

调查瑞利-泰勒不稳定经典技术包括使用压缩气体1，火箭2或线性电动机3反转重力的有效方向，并加快向致密流体较轻流体。其他作者如： 4，5，6已分离的重力不稳定层与被除去以发起的流动的障碍。然而，在一个旋转的分层的情况下，抛物线初始界面施加显著技术困难实验。我们希望能够在分层自旋成固体旋转，然后才开始流为了研究旋转时瑞利 - 泰勒不稳定的影响。我们在这里所采用的方法是使用的磁场超导磁体操纵两种液体的有效重量以引发流动。我们创建一个使用标准浮选技术的重力稳定两层分层。上部层比下部层的密度小，因此该系统是瑞利 - 泰勒稳定。然后，该分层纺丝机，直到两个层都是在固体旋转和抛物线界面观察。这些实验使用具有低磁化率，流体|χ| 〜10 -6 - 10 -5相比，一个铁磁流体。磁场的占主导地位的影响施加车身力每一层改变有效重量。上层是弱顺磁性，而下层是弱抗磁性。当施加的磁场，而上层朝向磁铁吸引下层从磁铁排斥。瑞利 - 泰勒不稳定与高梯度磁场中的应用来实现。我们还观察到，INC。reasing流体的动态粘度在每一层，增加长度尺度的不稳定性。

图。图4示出在两种流体之间的界面处的瑞利-泰勒不稳定的发展，用于四种不同的旋转速率：Ω= 1.89弧度-1（顶行），Ω= 3.32弧度-1，Ω= 4.68弧度秒- 1，和Ω= 8.74弧度-1（底行）。界面示出从T时刻演进= 0秒（左手列）为0.5秒的增量进行到t = 3.0秒（右栏）。因此右手列表示分别0.90，1.59，2.23，和4.17整圈从上到下?...

Watch this Scientific Journal Video about Magnetically Induced Rotating Rayleigh-Taylor Instability at JoVE.com

Magnetically Induced Rotating Rayleigh-Taylor Instability

We present a protocol for preparing a two-layer density-stratified liquid that can be spun-up into solid body rotation and subsequently induced into Rayleigh-Taylor instability by applying a gradient magnetic field.

磁感应旋转瑞利 - 泰勒不稳定性

Classical techniques for investigating the Rayleigh-Taylor instability include using compressed gasses1, rocketry2 or linear electric motors3 to reverse ...

magnetically-induced-rotating-rayleigh-taylor-instability

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9.4K 次观看.  University of Nottingham. We present a protocol for preparing a two-layer density-stratified liquid that can be spun-up into solid body rotation and subsequently induced into Rayleigh-Taylor instability by applying a gradient magnetic field.

视频: Magnetically Induced Rotating Rayleigh-Taylor Instability

Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses

Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a significant role in laser-material interaction, especially in the air environment1-11.
Early plasma evolution has been captured through pump-probe shadowgraphy1-3 and interferometry1,4-7. However, the studied time frames and applied laser parameter ranges are limited. For example, direct examinations of plasma front locations and electron number densities within a delay time of 100 picosecond (ps) with respect to the laser pulse peak are still very few, especially for the ultrashort pulse of a duration around 100 femtosecond (fs) and a low power density around 1014 W/cm2. Early plasma generated under these conditions has only been captured recently with high temporal and spatial resolutions12. The detailed setup strategy and procedures of this high precision measurement will be illustrated in this paper. The rationale of the measurement is optical pump-probe shadowgraphy: one ultrashort laser pulse is split to a pump pulse and a probe pulse, while the delay time between them can be adjusted by changing their beam path lengths. The pump pulse ablates the target and generates the early plasma, and the probe pulse propagates through the plasma region and detects the non-uniformity of electron number density. In addition, animations are generated using the calculated results from the simulation model of Ref. 12 to illustrate the plasma formation and evolution with a very high resolution (0.04 ~ 1 ps).
Both the experimental method and the simulation method can be applied to a broad range of time frames and laser parameters. These methods can be used to examine the early plasma generated not only from metals, but also from semiconductors and insulators.

An experimental method to examine the early plasma evolution induced by ultrashort laser pulses is described. Using this method, high quality images of early plasma are obtained with high temporal and spatial resolutions. A novel integrated atomistic model is used to simulate and explain the mechanisms of early plasma.

超短激光脉冲诱导的等离子体演化早期的调查

Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a ...

科研

工程学

Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle's Mapping and Quantification in Organ Tissue

Emission spectroscopy of laser-induced plasma was applied to elemental analysis of biological samples. Laser-induced breakdown spectroscopy (LIBS) performed on thin sections of rodent tissues: kidneys and tumor, allows the detection of inorganic elements such as (i) Na, Ca, Cu, Mg, P, and Fe, naturally present in the body and (ii) Si and Gd, detected after the injection of gadolinium-based nanoparticles. The animals were euthanized 1&#160;to 24 hr&#160;after intravenous injection of particles. A two-dimensional scan of the sample, performed using a motorized micrometric 3D-stage, allowed the infrared laser beam exploring the surface with a lateral resolution less than 100 &#956;m. Quantitative chemical images of Gd element inside the organ were obtained with sub-mM sensitivity. LIBS offers a simple and robust method to study the distribution of inorganic materials without any specific labeling. Moreover, the compatibility of the setup with standard optical microscopy emphasizes its potential to provide multiple images of the same biological tissue with different types of response:&#160;elemental, molecular, or cellular.

Laser-induced Breakdown Spectroscopy: A New Approach for Nanoparticle&#039;s Mapping and Quantification in Organ Tissue

Laser-induced breakdown spectroscopy performed on thin organ and tumor tissue successfully detected natural elements and artificially injected gadolinium (Gd), issued from Gd-based nanoparticles. Images of chemical elements reached a resolution of 100 &#956;m and quantitative sub-mM sensitivity. The compatibility of the setup with standard optical microscopy emphasizes its potential to provide multiple images of a same biological tissue.

激光诱导击穿光谱：对于纳米粒子的映射和定量的器官组织的新方法

Emission spectroscopy of laser-induced plasma was applied to elemental analysis of biological samples. Laser-induced breakdown spectroscopy (LIBS) ...

Laser-induced Forward Transfer for Flip-chip Packaging of Single Dies

Flip-chip (FC) packaging is a key technology for realizing high performance, ultra-miniaturized and high-density circuits in the micro-electronics industry. In this technique the chip and/or the substrate is bumped and the two are bonded via these conductive bumps. Many bumping techniques have been developed and intensively investigated since the introduction of the FC technology in 19601 such as stencil printing, stud bumping, evaporation and electroless/electroplating2. Despite the progress that these methods have made they all suffer from one or more than one drawbacks that need to be addressed such as cost, complex processing steps, high processing temperatures, manufacturing time and most importantly the lack of flexibility. In this paper, we demonstrate a simple and cost-effective laser-based bump forming technique known as Laser-induced Forward Transfer (LIFT)3. Using the LIFT technique a wide range of bump materials can be printed in a single-step with great flexibility, high speed and accuracy at RT. In addition, LIFT enables the bumping and bonding down to chip-scale, which is critical for fabricating ultra-miniature circuitry.

We demonstrate the use of the Laser-induced Forward Transfer (LIFT) technique for flip-chip assembly of optoelectronic components. This approach provides a simple, cost-effective, low-temperature, fast and flexible solution for fine-pitch bumping and bonding on chip-scale for achieving high-density circuits for optoelectronic applications.

激光诱导转发转移单人死于倒装芯片封装

Flip-chip (FC) packaging is a key technology for realizing high performance, ultra-miniaturized and high-density circuits in the micro-electronics ...

Visible-light Induced Reduction of Graphene Oxide Using Plasmonic Nanoparticle

Present work demonstrates the simple, chemical free, fast, and energy efficient method to produce reduced graphene oxide (r-GO) solution at RT using visible light irradiation with plasmonic nanoparticles. The plasmonic nanoparticle is used to improve the reduction efficiency of GO. It only takes 30 min&#160;at RT by illuminating the solutions with Xe-lamp, the r-GO solutions can be obtained by completely removing gold nanoparticles through simple centrifugation step. The spherical gold nanoparticles (AuNPs) as compared to the other nanostructures is the most suitable plasmonic nanostructure for r-GO preparation. The reduced graphene oxide prepared using visible light and AuNPs was equally qualitative as chemically reduced graphene oxide, which was supported by various analytical techniques such as UV-Vis spectroscopy, Raman spectroscopy, powder XRD and XPS. The reduced graphene oxide prepared with visible light shows excellent quenching properties over the fluorescent molecules modified on ssDNA and excellent fluorescence recovery for target DNA detection. The r-GO prepared by recycled AuNPs is found to be of same quality with that of chemically reduced r-GO. The use of visible light with plasmonic nanoparticle demonstrates the good alternative method for r-GO synthesis.

A simple protocol for the preparation of reduced graphene oxide using visible light and plasmonic nanoparticle is described.

可见光诱导的还原氧化石墨烯的使用电浆纳米粒子

Present work demonstrates the simple, chemical free, fast, and energy efficient method to produce reduced graphene oxide (r-GO) solution at RT using ...

Simulation of Human-induced Vibrations Based on the Characterized In-field Pedestrian Behavior

For slender and lightweight structures, vibration serviceability is a matter of growing concern, often constituting the critical design requirement. With designs governed by the dynamic performance under human-induced loads, a strong demand exists for the verification and refinement of currently available load models. The present contribution uses a 3D inertial motion tracking technique for the characterization of the in-field pedestrian behavior. The technique is first tested in laboratory experiments with simultaneous registration of the corresponding ground reaction forces. The experiments include walking persons as well as rhythmical human activities such as jumping and bobbing. It is shown that the registered motion allows for the identification of the time variant pacing rate of the activity. Together with the weight of the person and the application of generalized force models available in literature, the identified time-variant pacing rate allows to characterize the human-induced loads. In addition, time synchronization among the wireless motion trackers allows identifying the synchronization rate among the participants. Subsequently, the technique is used on a real footbridge where both the motion of the persons and the induced structural vibrations are registered. It is shown how the characterized in-field pedestrian behavior can be applied to simulate the induced structural response. It is demonstrated that the in situ identified pacing rate and synchronization rate constitute an essential input for the simulation and verification of the human-induced loads. The main potential applications of the proposed methodology are the estimation of human-structure interaction phenomena and the development of suitable models for the correlation among pedestrians in real traffic conditions.

A protocol is presented for the characterization of the in-field pedestrian behavior and the simulation of the resulting structural response. Field-tests demonstrate that the in situ identified pacing rate and synchronization rate among the participants constitute an essential input for the simulation and verification of the human-induced loads.

基于该特征场行人行为人类引起的振动模拟

For slender and lightweight structures, vibration serviceability is a matter of growing concern, often constituting the critical design requirement. With ...

Laser-induced Forward Transfer of Ag Nanopaste

Over the past decade, there has been much development of non-lithographic methods1-3 for printing metallic inks or other functional materials. Many of these processes such as inkjet3 and laser-induced forward transfer (LIFT)4 have become increasingly popular as interest in printable electronics and maskless patterning has grown. These additive manufacturing processes are inexpensive, environmentally friendly, and well suited for rapid prototyping, when compared to more traditional semiconductor processing techniques. While most direct-write processes are confined to two-dimensional structures and cannot handle materials with high viscosity (particularly inkjet), LIFT can transcend both constraints if performed properly. Congruent transfer of three dimensional pixels (called voxels), also referred to as laser decal transfer (LDT)5-9, has recently been demonstrated with the LIFT technique using highly viscous Ag nanopastes to fabricate freestanding interconnects, complex voxel shapes, and high-aspect-ratio structures. In this paper, we demonstrate a simple yet versatile process for fabricating a variety of micro- and macroscale Ag structures. Structures include simple shapes for patterning electrical contacts, bridging and cantilever structures, high-aspect-ratio structures, and single-shot, large area transfers using a commercial digital micromirror device (DMD) chip.

We demonstrate the use of the Laser-induced forward transfer technique (LIFT) for the printing of high-viscosity Ag paste. This technique offers a simple, low temperature, robust process for non-lithographically printing microscale 2D and 3D structures.

银纳米糊膏的激光诱导正向传输

Over the past decade, there has been much development of non-lithographic methods1-3 for printing metallic inks or other functional materials. Many of ...

Fabrication of 1-D Photonic Crystal Cavity on a Nanofiber Using Femtosecond Laser-induced Ablation

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using femtosecond laser-induced ablation. We show that thousands of periodic nano-craters are fabricated on an optical nanofiber by irradiating with just a single femtosecond laser pulse. For a typical sample, periodic nano-craters with a period of 350 nm and with diameter gradually varying from 50 - 250 nm over a length of 1 mm are fabricated on a nanofiber with diameter around 450 - 550 nm. A key aspect of such a nanofabrication is that the nanofiber itself acts as a cylindrical lens and focuses the femtosecond laser beam on its shadow surface. Moreover, the single-shot fabrication makes it immune to mechanical instabilities and other fabrication imperfections. Such periodic nano-craters on nanofiber, act as a 1-D PhC and enable strong and broadband reflection while maintaining the high transmission out of the stopband. We also present a method to control the profile of the nano-crater array to fabricate apodized and defect-induced PhC cavities on the nanofiber. The strong confinement of the field, both transverse and longitudinal, in the nanofiber-based PhC cavities and the efficient integration to the fiber networks, may open new possibilities for nanophotonic applications and quantum information science.

We present a protocol for fabricating 1-D photonic crystal cavities on subwavelength diameter silica fibers (optical nanofibers) using femtosecond laser-induced ablation.

1-D光子晶体空穴对纳米纤维使用飞秒激光诱导消融制造

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using ...

Preparation of Liquid Crystal Networks for Macroscopic Oscillatory Motion Induced by Light

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous light irradiation. The photo-excitation of dopants that can quickly dissipate light into heat, coupled with anisotropic thermal expansion and self-shadowing of the film, gives rise to the self-sustained deformation. The oscillations observed are influenced by the dimensions and the modulus of the film, and by the directionality and intensity of the light. The system developed offers applications in energy conversion and harvesting for soft-robotics and automated systems.
The general method described here consists of creating free-standing liquid crystalline films and characterizing the mechanical and thermal effects observed. The molecular alignment is achieved using alignment layers (rubbed polyimide), commonly used in the display manufacturing industry. To obtain actuators with large deformation, the mesogens are aligned and polymerized in a splay/bend configuration, i.e., with the director of the liquid crystals (LCs) going gradually from planar to homeotropic through the film thickness. Upon irradiation, the mechanical and thermal oscillations obtained are monitored with a high-speed camera. The results are further quantified by image analysis using an image processing program.

The goal of the protocol is to create liquid crystalline polymer films that can mechanically oscillate under continuous light irradiation. We describe in great detail the conception of free-standing films, from the liquid crystal alignment method to the photo-actuation. The experimental protocol applied to prepare this material is broadly applicable.

光诱导的宏观振荡运动液晶网络的制备

A strategy based on doped liquid crystalline networks is described to create mechanical self-sustained oscillations of plastic films under continuous ...

Fabrication Procedures and Birefringence Measurements for Designing Magnetically Responsive Lanthanide Ion Chelating Phospholipid Assemblies

Bicelles are tunable disk-like polymolecular assemblies formed from a large variety of lipid mixtures. Applications range from membrane protein structural studies by nuclear magnetic resonance (NMR) to nanotechnological developments including the formation of optically active and magnetically switchable gels. Such technologies require high control of the assembly size, magnetic response and thermal resistance. Mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and its lanthanide ion (Ln3+) chelating phospholipid conjugate, 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA), assemble into highly magnetically responsive assemblies such as DMPC/DMPE-DTPA/Ln3+ (molar ratio 4:1:1) bicelles. Introduction of cholesterol (Chol-OH) and steroid derivatives in the bilayer results in another set of assemblies offering unique physico-chemical properties. For a given lipid composition, the magnetic alignability is proportional to the bicelle size. The complexation of Ln3+ results in unprecedented magnetic responses in terms of both magnitude and alignment direction. The thermo-reversible collapse of the disk-like structures into vesicles upon heating allows tailoring of the assemblies&#39; dimensions by extrusion through membrane filters with defined pore sizes. The magnetically alignable bicelles are regenerated by cooling to 5 &#176;C, resulting in assembly dimensions defined by the vesicle precursors. Herein, this fabrication procedure is explained and the magnetic alignability of the assemblies is quantified by birefringence measurements under a 5.5 T magnetic field. The birefringence signal, originating from the phospholipid bilayer, further enables monitoring of polymolecular changes occurring in the bilayer. This simple technique is complementary to NMR experiments that are commonly employed to characterize bicelles.

Fabrication procedures for highly magnetically responsive lanthanide ion chelating polymolecular assemblies are presented. The magnetic response is dictated by the assembly size, which is tailored by extrusion through nanopore membranes. The assemblies&#39; magnetic alignability and temperature-induced structural changes are monitored by birefringence measurements, a complimentary technique to nuclear magnetic resonance and small angle neutron scattering.

设计磁响应稀土离子螯合磷脂组件的制备方法及双折射测量

Bicelles are tunable disk-like polymolecular assemblies formed from a large variety of lipid mixtures. Applications range from membrane protein structural ...

Uncoupling Coriolis Force and Rotating Buoyancy Effects on Full-Field Heat Transfer Properties of a Rotating Channel

An experimental method for exploring the heat transfer characteristics of an axially rotating channel is proposed. The governing flow parameters that characterize the transport phenomena in a rotating channel are identified via the parametric analysis of the momentum and energy equations referring to a rotating frame of reference. Based on these dimensionless flow equations, an experimental strategy that links the design of the test module, the experimental program and the data analysis is formulated with the attempt to reveal the isolated Coriolis-force and buoyancy effects on heat transfer performances. The effects of Coriolis force and rotating buoyancy are illustrated using the selective results measured from rotating channels with various geometries. While the Coriolis-force and rotating-buoyancy impacts share several common features among the various rotating channels, the unique heat transfer signatures are found in association with the flow direction, the channel shape and the arrangement of heat transfer enhancement devices. Regardless of the flow configurations of the rotating channels, the presented experimental method enables the development of physically consistent heat transfer correlations that permit the evaluation of isolated and interdependent Coriolis-force and rotating-buoyancy effects on the heat transfer properties of rotating channels.

Here, we present an experimental method for decoupling the interdependent Coriolis-force and rotating-buoyancy effects on full-field heat transfer distributions of a rotating channel.

解耦科里奥利力和旋转浮力对旋转通道全场传热性能的影响

An experimental method for exploring the heat transfer characteristics of an axially rotating channel is proposed. The governing flow parameters that ...