这项工作得到JSS KAKENHI授权号16H06037的支持。衷心感谢北海道大学佐佐木博士对HR-DSC的技术支持。

1.将全氟聚合物的液晶对准层制备到玻璃基板上<ol><li> 制备全氟聚合物溶液 <ol><li>通过以1:2的比例将全氟聚合物溶液（9重量％聚合物）溶解在市售溶剂中来制备1mL全氟聚合物溶液;这样可以确保0.5-1μm厚的均匀的薄膜被旋涂。 注意:请参阅材料清单，了解所用溶液和溶剂。 </li></ol></li><li> 将全氟聚合物涂覆在干净的玻璃基板上 <ol><li>通过在38或42kHz的碱性洗涤剂中超声波处理玻璃基板（典型尺寸:1cm×1cm）。反复用蒸馏水冲洗。一般冲洗10次以上，每次超声处理5分钟。 </li><li>将基材用于UV-O 3清洁剂10分钟。 </li><li>将20μL从步骤1.1的溶液滴入清洁的玻璃基质上工商业污水附加费。立即将溶液以3500rpm和室温旋涂70秒。将膜在80℃下烘烤60分钟以除去溶剂，并在200℃下烘烤60分钟以固化。 </li></ol></li></ol> LC细胞的制备<ol><li>使用光固化树脂和波长为365nm（1.1W / cm 2 ）的LED灯将两片涂有薄膜的玻璃基板胶合。通过使用微米级玻璃颗粒或聚萘二甲酸乙二醇酯膜，将两个基板之间的间隙厚度调整在2-100μm的范围内。 </li><li>在高于各向同性液体（I）的温度下，使用刮刀在毛细管力下将LC物质4&#39;-丁基-4-庚基 - 双环己基-4-甲腈（CCN47;0.2-10μL） 9引入制备的LC细胞中， （N）相变温度。 注意:CCN47具有负介电各向异性，相序为Cry 298.6 K SmA 301.3 KN 331.3 KI，其中Cry和SmA代表晶体和近晶相。不要在N相或SmA相中引入CCN47，因为可以促进流动引导的对准。 </li></ol>样品表征<ol><li> 通过偏光光学显微镜（POM）进行纹理观察10 <ol><li>观察POM下的LC细胞与4-100X物镜结合热阶段，以±0.1-K的精度控制样品温度。将纹理记录在超过5帧，以开尔文为间隔。在291-343K范围内冷却和加热时，请依次使用数码彩色照相机。 </li></ol></li><li> 介电光谱（DS） 11 <ol><li>制备具有ITO电极的LC电池，其可以具有正方形或圆形并且可以在两种基板上商业购买。将引线焊接到每个基板。 注意:请参阅所用基材的材料清单。 </li><li>使用商用阻抗/增益相位分析仪测量LC单元的电容或介电常数，与POM一样。确保在每次测量之前均衡样品的状态。通过每5分钟手动测量LC电池的电容来测量电容的时间依赖性或LC单元的介电常数。 </li><li>仅当LC单元的电容或介电常数变得非时间依赖时才启动DS测量。 </li></ol></li><li> 高分辨率差示扫描量热法（HR-DSC） 12 <ol><li>将LC细胞置于自制的HR-DSC中，与POM（ 不使用DSC平底锅）完全相同。参考参考12设计和构建HR-DSC并学习如何使用它。以0.05-0.10 K / min的扫描速率进行测量，以提高最低温度解析度呃。 </li></ol></li><li> 放射X射线衍射（GI-XRD） 13 <ol><li>将LC单元（用于POM或DSC）或具有2至5μLCCN47液滴的样品放置在GI-XRD样品台上的涂覆基材上，该样品台应配备温度控制器。 </li><li>在冷却和加热下，在291-343 K范围内的所需温度下将样品平衡超过10分钟。 </li><li>在样品上使用入射的X射线束，以0.05-0.10°的微小入射角提取分子取向和排列/结构的表面信息。摆动X射线束的入射角，找到衍射强度最强的最佳入射角。以最佳入射角度进行测量。 注意:请注意，GI-XRD可以探测纳米尺度的界面特性，从而最大化来自薄层的信号同时尽量减少大量信号。注意，除了GI-XRD之外，正常的XRD几何不是表面敏感的方法，因为X射线辐射束具有大的材料穿透深度。 </li></ol></li></ol>

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	<li>Woltman, S. J., Jay, G. D., Crawford, G. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liquid-Crystal+Materials+Find+a+New+Order+in+Biomedical+Applications.">Liquid-Crystal Materials Find a New Order in Biomedical Applications.</a> Nat. Mater. 6 (12), 929-938 (2007).</li><li>Carlton, R. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+and+Biological+Sensing+Using+Liquid+Crystals.">Chemical and Biological Sensing Using Liquid Crystals.</a> Liq. Cryst.Rev. 1 (1), 29-51 (2013).</li><li>Patel, J. S., Yokoyama, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+Anchoring+Transition+in+Liquid+Crystals.">Continuous Anchoring Transition in Liquid Crystals.</a> Nature. 362, 525-527 (1993).</li><li>Senyuk, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+alignment,+anchoring+transitions,+optical+properties,+and+topological+defects+in+the+nematic+phase+of+thermotropic+bent-core+liquid+crystal+A131.">Surface alignment, anchoring transitions, optical properties, and topological defects in the nematic phase of thermotropic bent-core liquid crystal A131.</a> Phys Rev E. 82 (4 Pt 1), 041711 (2010).</li><li>Bechhoefer, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Critical+Behavior+in+Anchoring+Transitions+of+Nematic+Liquid+Crystals.">Critical Behavior in Anchoring Transitions of Nematic Liquid Crystals.</a> Phys. 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E. 86 (2), 022512 (2014).</li><li>Aya, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermodynamically+Anchoring-Frustrated+Surface+to+Trigger+Bulk+Discontinuous+Orientational+Transition.">Thermodynamically Anchoring-Frustrated Surface to Trigger Bulk Discontinuous Orientational Transition.</a> Langmuir. 32 (41), 10545-10550 (2016).</li><li>Dhara, S., Madhusudana, N. 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作者没有什么可以披露的。

使用5-μmLC单元（ 图1a和b ）拍摄的10x POM图像清楚地表明，当以一级方式温度变化时，本体LC分子的取向状态在P和V取向之间转变。这是由领域成核和生长过程标记的，其新方向与初始取向不同，为90°。冷却和加热时的转变温度分别为321.5K和325.3K。由于CCN47的双折射为〜0.02 9 ，当LC单元的厚度在5-20μm的范围内时，Schlieren纹理的可视性是好的。如果厚度小于...

近年来，人们越来越关心学习如何响应于外部刺激的表面分子的动态分子特征和结构可能影响LC状态下材料的体取向。一个例子是使用LC生物传感器作为LC1,2的新应用。为了量化检测到多少目标生物物种，重要的是要知道接触粘附目标分子的界面LC如何变化和演化，同时也检测它们如何将其性质转移到体内。 使用模型来追求这些答案，我们从具有表面分子取向和短程排序的系统开始，热力学变化。这些系统允许我们以系统的方式将表面取向和排序的变化与所得到的体积方向相关联。最近，我们发现了几个显示o的LC系统自发体积分子取向随温度变化。原则上，定向转换可以分为准二阶3,4或准一阶转换5,6,7,8。前者伴随着温度变化时的连续大分子重新取向，而后者则表现出不连续的。在本文中，我们描述了P和V定向状态之间的准一阶方向的取向转变。它通过改变温度在单向向（N）相中进行。详细情况将在代表结果和讨论中提供。 由于体积的取向变化应受表面分子取向的变化和短期的限制很明显的是，该系统可以潜在地了解表面分子取向和短程排序的热力学变化如何影响体取向。在本文中，为了理解上述问题，我们使用四种补充方法（ 即 POM，DS，HR-DSC和GI-XRD）解决了三个问题:（1）定向过渡是什么样的？ （2）取向转变是否可热？ （3）为什么和如何发生方向转变？

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>CYTOP</td>
			<td>Asahi Glass Co. Ltd.</td>
			<td>CTX-809A</td>
			<td></td>
		</tr>
		<tr>
			<td>Solvent for CYTOP</td>
			<td>Asahi Glass Co. Ltd.</td>
			<td>CT-180 Sol.</td>
			<td></td>
		</tr>
		<tr>
			<td>Alkaline detergent</td>
			<td>Merck KGaA</td>
			<td>Extran MA01</td>
			<td></td>
		</tr>
		<tr>
			<td>NOA61</td>
			<td>Norland Products, Inc.</td>
			<td>#37-322</td>
			<td>Purchasable from Edmund Optics</td>
		</tr>
		<tr>
			<td>AL1254</td>
			<td>JSR Corporation</td>
			<td></td>
			<td>Planar alignment material in self-made cells</td>
		</tr>
		<tr>
			<td>4&#8217;-butyl-4-heptyl-bicyclohexyl-4-carbonitrile</td>
			<td>Nematel GmbH &#38; Co. KG</td>
			<td></td>
			<td>Custom-made</td>
		</tr>
		<tr>
			<td>UV-O3 cleaner</td>
			<td>Technovision Inc.</td>
			<td>UV-208</td>
			<td></td>
		</tr>
		<tr>
			<td>Hot-stage system</td>
			<td>Mettler Toledo</td>
			<td>HS82</td>
			<td></td>
		</tr>
		<tr>
			<td>High-Definition Color Camera Head</td>
			<td>Nikon</td>
			<td>DS-Fi1</td>
			<td></td>
		</tr>
		<tr>
			<td>Impedance/gain-phase analyzer</td>
			<td>Solartron Analytical</td>
			<td>1260</td>
			<td></td>
		</tr>
		<tr>
			<td>Indium Tin Oxide (ITO)-coated substrate</td>
			<td>GEOMATEC Co. Ltd.</td>
			<td></td>
			<td>Custom-made</td>
		</tr>
	</tbody>
</table>

orientational transition in a liquid crystal triggered by the thermodynamic growth of interfacial wetting sheets

在液晶（LC）物理化学中，表面附近的分子在控制体取向方面起着很大的作用。到目前为止，主要是为了在LC显示器中实现期望的分子取向状态，已经深入研究了LC的"静态"表面性质，即所谓的表面锚定。根据经验，一旦LC的初始取向通过特定的表面处理（例如用特定取向层的摩擦或处理）"锁定"，则几乎不随温度变化。在这里，我们提出一个体现温度变化的方向转变的系统，与共识相冲突。在转换过程中，体积LC分子经历取向旋转，在高温下的平面（P）取向与低温下的垂直（V）取向之间呈90°，以一阶过渡方式。我们通过偏振光学显微镜跟踪热力学表面锚固行为（POM），介电光谱（DS），高分辨率差示扫描量热法（HR-DSC）和掠入射X射线衍射（GI-XRD），并达到合理的物理解释:转变由表面生长引发润湿片材，其在本体上局部抵抗P取向局部施加V取向。这种景观将提供一个通用的链接，说明在许多液相色谱系统中平衡体取向受到表面定向取向的影响。在我们的表征中，通过提供关于LC分子的取向的空间分布的信息，POM和DS是有利的。 HR-DSC提供关于转换的精确热力学信息的信息，由于分辨率有限，传统DSC仪器无法解决。 GI-XRD提供关于表面特异性分子取向和短程排序的信息。本文的目的是提出一种用于准备展示transi的样品的方案并演示如何通过上述方法分析体积和表面上的热力学结构变化。

在温度变化期间收集POM图像，DS数据，HR-DSC数据和GI-XRD图案，特别是在冷却和加热两者的取向过渡附近。 图1表示在冷却（加热）期间从P（V）到V（P）取向状态的取向转变的POM观察期间由POM和DS测量形成的纹理的演变。显示了基于POM观察的取向转换过程中的重新定向过程（ 图1a ）。...

Watch this Scientific Journal Video about Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets at JoVE.com

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

在这里，我们提出一种协议来触发液晶响应于温度的取向转变。描述了制备样品以观察转变和详细过渡演化的方法。

由界面润湿片的热力学生长触发的液晶中的定向转变

In liquid crystal (LC) physical chemistry, molecules near the surface play a great role in controlling bulk orientation. Thus far, mainly to achieve ...

orientational-transition-liquid-crystal-triggered-thermodynamic

Research

JoVE Journal

Engineering

7.1K 次观看.  RIKEN Center for Emergent Matter Science (CEMS). 在这里，我们提出一种协议来触发液晶响应于温度的取向转变。描述了制备样品以观察转变和详细过渡演化的方法。 

视频: Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets

Dry Oxidation and Vacuum Annealing Treatments for Tuning the Wetting Properties of Carbon Nanotube Arrays

In this article, we describe a simple method to reversibly tune the wetting properties of vertically aligned carbon nanotube (CNT) arrays. Here, CNT arrays are defined as densely packed multi-walled carbon nanotubes oriented perpendicular to the growth substrate as a result of a growth process by the standard thermal chemical vapor deposition (CVD) technique.1,2 These CNT arrays are then exposed to vacuum annealing treatment to make them more hydrophobic or to dry oxidation treatment to render them more hydrophilic. The hydrophobic CNT arrays can be turned hydrophilic by exposing them to dry oxidation treatment, while the hydrophilic CNT arrays can be turned hydrophobic by exposing them to vacuum annealing treatment. Using a combination of both treatments, CNT arrays can be repeatedly switched between hydrophilic and hydrophobic.2 Therefore, such combination show a very high potential in many industrial and consumer applications, including drug delivery system and high power density supercapacitors.3-5
The key to vary the wettability of CNT arrays is to control the surface concentration of oxygen adsorbates. Basically oxygen adsorbates can be introduced by exposing the CNT arrays to any oxidation treatment. Here we use dry oxidation treatments, such as oxygen plasma and UV/ozone, to functionalize the surface of CNT with oxygenated functional groups. These oxygenated functional groups allow hydrogen bond between the surface of CNT and water molecules to form, rendering the CNT hydrophilic. To turn them hydrophobic, adsorbed oxygen must be removed from the surface of CNT. Here we employ vacuum annealing treatment to induce oxygen desorption process. CNT arrays with extremely low surface concentration of oxygen adsorbates exhibit a superhydrophobic behavior.

This article describes a simple method to fabricate vertically aligned carbon nanotube arrays by CVD and to subsequently tune their wetting properties by exposing them to vacuum annealing or dry oxidation treatment.

干式氧化及真空退火处理调整的润湿性能的碳纳米管阵列

In this article, we describe a simple method to reversibly  tune the wetting properties of vertically aligned carbon nanotube (CNT) arrays.  Here, CNT ...

科研

工程学

Sputter Growth and Characterization of Metamagnetic B2-ordered FeRh Epilayers

Chemically ordered alloys are useful in a variety of magnetic nanotechnologies. They are most conveniently prepared at an industrial scale using sputtering techniques. Here we describe a method for preparing epitaxial thin films of B2-ordered FeRh by sputter deposition onto single crystal MgO substrates. Deposition at a slow rate onto a heated substrate allows time for the adatoms to both settle into a lattice with a well-defined epitaxial relationship with the substrate and also to find their proper places in the Fe and Rh sublattices of the B2 structure. The structure is conveniently characterized with X-ray reflectometry and diffraction and can be visualised directly using transmission electron micrograph cross-sections. B2-ordered FeRh exhibits an unusual metamagnetic phase transition: the ground state is antiferromagnetic but the alloy transforms into a ferromagnet on heating with a typical transition temperature of about 380 K. This is accompanied by a 1% volume expansion of the unit cell: isotropic in bulk, but laterally clamped in an epilayer. The presence of the antiferromagnetic ground state and the associated first order phase transition is very sensitive to the correct equiatomic stoichiometry and proper B2 ordering, and so is a convenient means to demonstrate the quality of the layers that can be deposited with this approach. We also give some examples of the various techniques by which the change in phase can be detected.

A method to prepare epitaxial layers of ordered alloys by sputtering is described. The B2-ordered FeRh compound is used as an example, as it displays a metamagnetic transition that depends sensitively on the degree of chemical order and the exact composition of the alloy.

变磁B2有序化的FeRh外延层溅射生​​长和表征

Chemically ordered alloys are useful in a variety of magnetic nanotechnologies. They are most conveniently prepared at an industrial scale using ...

Characterization of Recombination Effects in a Liquid Ionization Chamber Used for the Dosimetry of a Radiosurgical Accelerator

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via stereotactic radiotherapy where positioning accuracy allows delivering very high doses per fraction in a small volume of the patient. Dosimetric measurements on medical accelerators are conventionally realized using air-filled ionization chambers. However, in small beams these are subject to nonnegligible perturbation effects. This study focuses on liquid ionization chambers, which offer advantages in terms of spatial resolution and low fluence perturbation. Ion recombination effects are investigated for the microLion detector (PTW) used with the Cyberknife system (Accuray). The method consists of performing a series of water tank measurements at different source-surface distances, and applying corrections to the liquid detector readings based on simultaneous gaseous detector measurements. This approach facilitates isolating the recombination effects arising from the high density of the liquid sensitive medium and obtaining correction factors to apply to the detector readings. The main difficulty resides in achieving a sufficient level of accuracy in the setup to be able to detect small changes in the chamber response.

A growing number of radiation therapy devices offer the advantage of delivering the dose through very small beams to the tumor, allowing for increased conformity and higher doses per fraction. Many different detectors can be used for the dosimetry of these small fields. In the present study, the effect of ion recombination is investigated for a liquid ionization chamber using a stereotactic radiation therapy system.

重组的影响在液体电离室表征用于一个电波加速器的剂量学

Most modern radiation therapy devices allow the use of very small fields, either through beamlets in Intensity-Modulated Radiation Therapy (IMRT) or via ...

Ultrasound Velocity Measurement in a Liquid Metal Electrode

A growing number of electrochemical technologies depend on fluid flow, and often that fluid is opaque. Measuring the flow of an opaque fluid is inherently more difficult than measuring the flow of a transparent fluid, since optical methods are not applicable. Ultrasound can be used to measure the velocity of an opaque fluid, not only at isolated points, but at hundreds or thousands of points arrayed along lines, with good temporal resolution. When applied to a liquid metal electrode, ultrasound velocimetry involves additional challenges: high temperature, chemical activity, and electrical conductivity. Here we describe the experimental apparatus and methods that overcome these challenges and allow the measurement of flow in a liquid metal electrode, as it conducts current, at operating temperature. Temperature is regulated within &#177;2 &#176;C using a Proportional-Integral-Derivative (PID) controller that powers a custom-built furnace. Chemical activity is managed by choosing vessel materials carefully and enclosing the experimental setup in an argon-filled glovebox. Finally, unintended electrical paths are carefully prevented. An automated system logs control settings and experimental measurements, using hardware trigger signals to synchronize devices. This apparatus and these methods can produce measurements that are impossible with other techniques, and allow optimization and control of electrochemical technologies like liquid metal batteries.

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

超声速度测量的液态金属电极

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

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75&#176;. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm2, respectively, has decreased the CA to near 15&#176;, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer&#8217;s surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of&#160;the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm2 and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103&#176;. The XPS results indicate ArF laser induced formation of Si&#8211;(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

We report on a process of in situ alteration of HF treated Si (001) surface into a hydrophilic or hydrophobic state by irradiating samples in microfluidic chambers filled with&#160;H2O2/H2O solution (0.01%-0.5%) or methanol solutions using pulsed UV laser of a relative low pulse fluence.

硅表面润湿性的选择区域改性脉冲紫外激光照射在液体环境

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of ...

How to Ignite an Atmospheric Pressure Microwave Plasma Torch without Any Additional Igniters

This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a stable and continuous operation of the plasma is possible and the plasma torch can be used for many different applications. On one hand, the hot (3,600 K gas temperature) plasma can be used for chemical processes and on the other hand the cold afterglow (temperatures down to almost RT) can be applied for surface processes. For example chemical syntheses are interesting volume processes. Here the microwave plasma torch can be used for the decomposition of waste gases which are harmful and contribute to the global warming but are needed as etching gases in growing industry sectors like the semiconductor branch. Another application is the dissociation of CO2. Surplus electrical energy from renewable energy sources can be used to dissociate CO2 to CO and O2. The CO can be further processed to gaseous or liquid higher hydrocarbons thereby providing chemical storage of the energy, synthetic fuels or platform chemicals for the chemical industry. Applications of the afterglow of the plasma torch are the treatment of surfaces to increase the adhesion of lacquer, glue or paint, and the sterilization or decontamination of different kind of surfaces. The movie will explain how to ignite the plasma solely by microwave power without any additional igniters, e.g., electric sparks. The microwave plasma torch is based on a combination of two resonators &#8212; a coaxial one which provides the ignition of the plasma and a cylindrical one which guarantees a continuous and stable operation of the plasma after ignition. The plasma can be operated in a long microwave transparent tube for volume processes or shaped by orifices for surface treatment purposes.

This movie shows how an atmospheric plasma torch can be ignited by microwaves with no additional igniters and provides a stable and continuous plasma operation suitable for plenty of applications.

如何点燃常压微波等离子体炬没有任何额外的点火器

This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a ...

How to Build a Vacuum Spring-transport Package for Spinning Rotor Gauges

The spinning rotor gauge (SRG) is a high-vacuum gauge often used as a secondary or transfer standard for vacuum pressures in the range of 1.0 x 10-4 Pa to 1.0 Pa. In this application, the SRGs are frequently transported to laboratories for calibration. Events can occur during transportation that change the rotor surface conditions, thus changing the calibration factor. To assure calibration stability, a spring-transport mechanism is often used to immobilize the rotor and keep it under vacuum during transport. It is also important to transport the spring-transport mechanism using packaging designed to minimize the risk of damage during shipping. In this manuscript, a detailed description is given on how to build a robust spring-transport mechanism and shipping container. Together these form a spring-transport package. The spring-transport package design was tested using drop-tests and the performance was found to be excellent. The present spring-transport mechanism design keeps the rotor immobilized when experiencing shocks of several hundred g (g = 9.8 m/sec2 and is the acceleration due to gravity), while the shipping container assures that the mechanism will not experience shocks greater than about 100 g during common shipping mishaps (as defined by industry standards).

Here we describe how to build a robust spring-transport mechanism for a spinning rotor gauge. This device securely immobilizes the rotor and keeps it under vacuum during transportation. We also describe packaging that minimizes the risk of damage during transport. Tests show our design works for typical shocks during transport.

如何建立一个真空Spring的运输包装为纺转子规

The spinning rotor gauge (SRG) is a high-vacuum gauge often used as a secondary or transfer standard for vacuum pressures in the range of 1.0 x 10-4 Pa to ...

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

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

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

与尺寸可控液体剥离的过渡金属二硫属化物纳米片和厚度的制备:艺术议定书的国家

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

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 ...

Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication

We have demonstrated that through the sulfurization of transition metal films such as molybdenum (Mo) and tungsten (W), large-area and uniform transition metal dichalcogenides (TMDs) MoS2 and WS2 can be prepared on sapphire substrates. By controlling the metal film thicknesses, good layer number controllability, down to a single layer of TMDs, can be obtained using this growth technique. Based on the results obtained from the Mo film sulfurized under the sulfur deficient condition, there are two mechanisms of (a) planar MoS2 growth and (b) Mo oxide segregation observed during the sulfurization procedure. When the background sulfur is sufficient, planar TMD growth is the dominant growth mechanism, which will result in a uniform MoS2 film after the sulfurization procedure. If the background sulfur is deficient, Mo oxide segregation will be the dominant growth mechanism at the initial stage of the sulfurization procedure. In this case, the sample with Mo oxide clusters covered with few-layer MoS2 will be obtained. After sequential Mo deposition/sulfurization and W deposition/sulfurization procedures, vertical WS2/MoS2 hetero-structures are established using this growth technique. Raman peaks corresponding to WS2 and MoS2, respectively, and the identical layer number of the hetero-structure with the summation of individual 2D materials have confirmed the successful establishment of the vertical 2D crystal hetero-structure. After transferring the WS2/MoS2 film onto a SiO2/Si substrate with pre-patterned source/drain electrodes, a bottom-gate transistor is fabricated. Compared with the transistor with only MoS2 channels, the higher drain currents of the device with the WS2/MoS2 hetero-structure have exhibited that with the introduction of 2D crystal hetero-structures, superior device performance can be obtained. The results have revealed the potential of this growth technique for the practical application of 2D crystals.

Through the sulfurization of pre-deposited transition metals, large-area and vertical 2D crystal hetero-structures can be fabricated. The film transferring and device fabrication procedures are also demonstrated in this report.

硫化过渡金属膜制备大面积垂直2D 晶体杂化结构

We have demonstrated that through the sulfurization of transition metal films such as molybdenum (Mo) and tungsten (W), large-area and uniform transition ...

由界面润湿片的热力学生长触发的液晶中的定向转变

摘要

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此视频中的章节

干式氧化及真空退火处理调整的润湿性能的碳纳米管阵列

变磁B2有序化的FeRh外延层溅射生长和表征

重组的影响在液体电离室表征用于一个电波加速器的剂量学

超声速度测量的液态金属电极

硅表面润湿性的选择区域改性脉冲紫外激光照射在液体环境

如何点燃常压微波等离子体炬没有任何额外的点火器

如何建立一个真空Spring的运输包装为纺转子规

与尺寸可控液体剥离的过渡金属二硫属化物纳米片和厚度的制备:艺术议定书的国家

光诱导的宏观振荡运动液晶网络的制备

硫化过渡金属膜制备大面积垂直2D 晶体杂化结构

由界面润湿片的热力学生长触发的液晶中的定向转变

摘要

探索更多视频

此视频中的章节

干式氧化及真空退火处理调整的润湿性能的碳纳米管阵列

变磁B2有序化的FeRh外延层溅射生​​长和表征

重组的影响在液体电离室表征用于一个电波加速器的剂量学

超声速度测量的液态金属电极

硅表面润湿性的选择区域改性脉冲紫外激光照射在液体环境

如何点燃常压微波等离子体炬没有任何额外的点火器

如何建立一个真空Spring的运输包装为纺转子规

与尺寸可控液体剥离的过渡金属二硫属化物纳米片和厚度的制备:艺术议定书的国家

光诱导的宏观振荡运动液晶网络的制备

硫化过渡金属膜制备大面积垂直2D 晶体杂化结构

变磁B2有序化的FeRh外延层溅射生长和表征