我们感谢A.从巴伊兰大学Sharoni提供超导膜。这项研究是由欧洲研究理事会资助ERC-2014-STG- 639792支持，居里夫人职业集成格兰特FP7-人2012年CIG-333799，以色列科学基金会资助环球基金系列 - 1102年至1113年。

1.访问扫描SQUID系统<ol><li>使用扫描SQUID系统，其包括芯片9，10，粘滑粗略运动阶段，以及用于精细运动的基于压电的扫描器上制造一个SQUID传感器。 见图1。 </li><li>擦亮鱿鱼片绕成圈拾音一个角落。芯片的材料需要被去除一路拾取循环。 <ol><li>轻轻打磨鱿鱼，使用5到0.5微米的非磁性抛光纸。 注:在抛光阶段之后拾取器环可以带入接近或接触时，与样品。 </li></ol></li></ol> 2.铌（Nb）的薄膜与直流（DC）溅射沉积<ol><li>得到的基板。在这项工作中，使用具有氧化硅的500nm的掺硼的硅衬底。如钛酸锶和MgO其它基底是可能的。 </li><li>到达基地pressu重10 -7乇的在腔室中。预溅射在2.4毫乇的1.8埃/ s的10分钟的沉积速率的压力在室温下用99.95％的Nb靶的蒸发室，在氩气环境中。注意，当在腔室中的基准压力小于10 -7乇沉积过程只能启动。如果压力较高的重复预溅射阶段。 </li><li>放置基板在腔室中。 </li><li>存款铌薄膜通过在含有1.8埃/秒的沉积速率2.4毫托的压力在从99.95％的Nb靶室温溅射，在氩气环境中。 </li></ol> 3.样本尖对准<ol><li>在此阶段，对准传感器芯片与样本，使得运动的旋涡当芯片的顶端，使与样品接触。为了实现这一点，使用至少4°的取向角度。 </li><li>胶上的导电板的柔性悬臂有介电层。然后，胶SQUID志P的悬臂。悬臂和一个静态板之间的电容确定与样品和应力的施加程度的接触。 </li><li>在显微镜载样本。样品粘到一个指定样品用清漆或银膏装入。胶安装于Z压电元件（ 图1a）。 </li><li>在粘滑粗运动系统连接到控制器。 </li><li>的正面和芯片的侧 - 从两个角度设置光学成像。使用两个望远镜放置在翻译阶段，定向到芯片的正面和其一侧。 </li><li>使用Z粘滑粗略运动阶段，从传感器移动样品为1微米的距离，以使该传感器的反射是在样品上可见的。 注意:在这个阶段的样本和传感器之间的接触可能会伤害乌贼。 </li><li>移动样品0.5 - 从传感器1毫米远使用Z粘滑粗略运动阶段，以防止向S损坏镑。 </li><li>旋转定位螺钉（ 图1a），以获得等于前方角度（ 即，角芯片的前端的侧面使得与它的反射， 如图1c所示）。 </li><li>移动样品至1微米距离传感器的距离。检查的角度，必要时重复步骤3.7和3.8。 </li><li>旋转定位螺钉，以得到的传感器和样品（ 图1d）之间4度的角度。确保芯片的前端部，其与样品接触的部分。 </li></ol> 4.测量<ol><li>扫描头（ 图1a）加载到4K的冷却系统。 注:扫描头应该被连接到一个冷板，并通过真空罐包围。导线围绕所述罐的线圈施加外部磁场（几个高斯低字段是足够本研究）。盖此设置与睦金属屏蔽。 </li><li>酷派在马格纳的存在抽动领域，通过周围的显微镜线圈通电。仔细选择的场强以达到所需涡流密度。使用1Φ0 = 20.7克/ 平方微米来计算冷却时间字段。例如，对于在10微米10微米的区域10的涡流，申请2.07 G。 </li><li>为了改变上述超导转变温度的新型涡密度热样品（铌，加热至10 K）。应用新领域。 </li><li>酷样品4.2 K. </li><li>关闭磁场关闭。打开鱿鱼。 </li><li>靠拢使用粘滑粗运动系统鱿鱼样品。 <ol><li>适用于Z-粘滑立方体增加电压移动样品接近SQUID芯片。 </li><li>应用该悬臂和板之间的电压，用于读取使用电容电桥（0.1-1 V典型的）的电容。 </li><li>扫在Z压电元件上的电压。测量悬臂与高原之间的电容即如果出现在电容大的变化，所述样品与所述SQUID芯片接触。 </li><li>如果样品没有做出与芯片接触，重复步骤4.6.1-4.6.3，直到接触观察。 </li><li>可选:使用场运动来调节针尖与样品之间的间隔，因此，接触发生在低电压（0 - 10伏施加在Z压电）。 </li><li>一旦有接触，重复在多个位置，以确定所述表面的倾斜角，并确定样品的相对于传感器的平面，步骤4.6.2-4.6.3。 </li></ol></li><li>扫，以相对于所述传感器的样品移动的X和Y压电元件上的电压。扫描在恒定高度的样品上方，而不针尖与样品之间的接触，以图涡旋分布。由根据X和Y的位置在Z压电改变电压达到一恒定扫描高度，并在4.6限定的平面。 </li><li>选择一个旋涡和扫描腌肉第二它精确地确定其中心的位置。注意，涡流位置是相对于所述SQUID的拾取器循环，而不是到接触点。 </li><li>关闭SQUID关闭。 </li><li>施加电压是比接地电压于z压电和任一抽头更大旁边的涡流中心或通过在样品上缓慢拖动传感器（在与样品接触）到所需的位置扫涡流。涡流将致力于水龙头或扫方向移动。典型的值添加到施加ž压电电压是2-5 V. </li><li>打开鱿鱼。 </li><li>再次图像在一个恒定的高度，而不接触到定位涡流的新位置。 </li></ol>

<ol>
	<li>Olson Reichhardt, C. J., Hastings, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Do+Vortices+Entangle?.">Do Vortices Entangle?.</a> Phys. Rev. Lett. 92, 157002 (2004).</li><li>Milo&#353;evi&#263;, M. V., Berdiyorov, G. R., Peeters, F. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluxonic+cellular+automata.">Fluxonic cellular automata.</a> Appl. Phys. Lett. 91, 212501 (2007).</li><li>Kalisky, 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=Scanning+Probe+Manipulation+of+Magnetism+at+the+LaAlO3/SrTiO3+Heterointerface.">Scanning Probe Manipulation of Magnetism at the LaAlO3/SrTiO3 Heterointerface.</a> Nano Lett. 12, 4055-4059 (2012).</li><li>Silva, C. C. D. S., Van de Vondel, J., Morelle, M., Moshchalkov, V. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+multiple+reversals+of+a+ratchet+effect.">Controlled multiple reversals of a ratchet effect.</a> Nature. 440, 651-654 (2006).</li><li>Kalisky, 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=Dynamics+of+single+vortices+in+grain+boundaries:+I-V+characteristics+on+the+femtovolt+scale.">Dynamics of single vortices in grain boundaries: I-V characteristics on the femtovolt scale.</a> Appl. Phys. Lett. 94, 202504 (2009).</li><li>Embon, L., 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=Probing+dynamics+and+pinning+of+single+vortices+in+superconductors+at+nanometer+scales.">Probing dynamics and pinning of single vortices in superconductors at nanometer scales.</a> Sci. Rep. 5, 7598 (2015).</li><li>Auslaender, O. M., 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=Mechanics+of+individual+isolated+vortices+in+a+cuprate+superconductor.">Mechanics of individual isolated vortices in a cuprate superconductor.</a> Nature Phys. 5, 35-39 (2008).</li><li>Kalisky, 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=Behavior+of+vortices+near+twin+boundaries+in+underdoped+Ba(Fe1-xCox)2As2.">Behavior of vortices near twin boundaries in underdoped Ba(Fe1-xCox)2As2.</a> Phys. Rev. B. 83, 064511 (2011).</li><li>Huber, M. E., 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=Gradiometric+micro-SQUID+susceptometer+for+scanning+measurements+of+mesoscopic+samples.">Gradiometric micro-SQUID susceptometer for scanning measurements of mesoscopic samples.</a> Rev. Sci. Instrum. 79, 053704 (2008).</li><li>Koshnick, N. C., 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=A+terraced+scanning+super+conducting+quantum+interference+device+susceptometer+with+submicron+pickup+loops.">A terraced scanning super conducting quantum interference device susceptometer with submicron pickup loops.</a> Appl. Phys. Lett. 93, 243101 (2008).</li><li>Kremen, A., 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=Mechanical+Control+of+Individual+Superconducting+Vortices.">Mechanical Control of Individual Superconducting Vortices.</a> Nano Lett. 16, 1626-1630 (2016).</li></ol>

The authors have nothing to disclose.

旋涡的操纵成功取决于几个关键步骤。它以对准传感器成一角度，以使得芯片的末端将是第一个，使与样品接触是重要的。第二，要注意，施加在样品上的力是通过该芯片安装在悬臂的机械特性决定是很重要的。在弹性体制，所施加的力成比例的偏转中，x，根据虎克定律: F = -kx 其中k是弹簧常数，由杨氏模量的材料制成，并且它的物理尺寸决定的，并且由下式给出 K...

涡流是在纳米磁性物体，形成在2型超导体在外部磁场的存在。在一无缺陷样品，旋涡可以自由移动。然而，在材料的结果，其中对于旋涡能量上有利的降低超导区域不同的缺陷。涡流倾向于装饰这些区域，也被称为钉扎部位。在这种情况下，移动一个涡流所需的力必须大于钉扎力越大。的涡流，如涡流密度，相互作用的强度和范围的性质，可以通过外部场，温度，或样品的几何形状容易地确定。控制这些性质的能力使得它们成为凝聚态行为可以容易地调整，以及合适的候选者良好的模型系统用于电子应用的1，2。个别旋涡的位置的控制是这样的LO的设计必需gical元素。 磁性纳米粒子的机械控制之前已经完成。 Kalisky 等。最近使用扫描超导量子干涉仪（SQUID）研究局部机械应力对铁磁补丁复合氧化物接口3的影响。他们能够通过扫描在接触来改变贴片的方向，按压SQUID的尖端到样品，在这个过程施加到1μN的力。我们已在以移动涡流应用于我们的协议类似的方法。 在涡流操纵现有的研究，运动通过施加电流到样品来实现，从而产生洛伦兹力4，5，6。虽然这种方法是有效的，它不是本地的，并且为了控制单个涡流，则需要额外的制造。涡也可以MANIPulated通过用磁力显微镜（MFM）或用SQUID励磁线圈7,8施加外部磁场，例如。这个方法是有效的和局部的，但这些工具所施加的力小，并且只能在高温下，接近超导体的临界温度克服钉扎力。我们的协议允许在低温（4 K）的有效，本地操作没有样品的额外的制造。 我们用扫描显微镜SQUID形象旋涡。该传感器被制造被抛光成一个角，并粘接在柔性悬臂的硅芯片上。悬臂用于表面的电容传感。该芯片被放置在一个角度的样品，使得接触点是在芯片的顶端。我们通过推动芯片放入样品申请高达2μN的力量。我们移动相对SQUID样品由压电元件。我们移动旋涡通过点击硅尖旁边的一个旋涡，或通过清扫它，触摸旋涡。

<table><tbody><tr><td>stick slip coarse motion system</td><td>attocube</td><td>ANPx-101</td><td>x,y motion</td></tr><tr><td>stick slip coarse motion system</td><td>attocube</td><td>ANPz-101</td><td>z motion</td></tr><tr><td>stick slip coarse motion system controller</td><td>Attocube</td><td>ANC 300</td><td></td></tr><tr><td>high voltage amplifier</td><td>Attocube</td><td>ANC 250</td><td></td></tr><tr><td>data acquisition card</td><td>National Instruments</td><td>NI&amp;nbsp;PCIe-6363</td><td></td></tr><tr><td>piezo elements</td><td>Piezo Systems Inc</td><td>T2C</td><td>non magnetic</td></tr><tr><td>low noise voltage preamplifier</td><td>Stanford Research Systems</td><td>SR 560</td><td></td></tr><tr><td>capacitance bridge</td><td>General Radio</td><td>1615A</td><td></td></tr><tr><td>telescope</td><td>NAVITAR</td><td>1-504516</td><td></td></tr><tr><td>camera</td><td>MOTICAM</td><td>MP2</td><td></td></tr><tr><td>dewar</td><td>Cryofab</td><td>N/A</td><td></td></tr><tr><td>insert</td><td>ICE oxford</td><td>N/A</td><td></td></tr><tr><td>Mu-metal shield</td><td>Amuneal</td><td>N/A</td><td></td></tr><tr><td>vacuum cap</td><td>ICE oxford</td><td>N/A</td><td></td></tr><tr><td>sputtering system</td><td>AJA international Inc</td><td>N/A</td><td></td></tr><tr><td>lapping film</td><td>3M</td><td>261X</td><td>non magnetic</td></tr><tr><td>Nb target</td><td>Kurt J. Lesker</td><td>EJTNBXX351A2</td><td></td></tr><tr><td>GE Varnish</td><td>CMR-Direct</td><td>02-33-001</td><td>for cryogenic heatsinking</td></tr><tr><td>Silver paste</td><td>Structure Probe Inc</td><td>05063-AB</td><td></td></tr></tbody></table>

scanning squid study of vortex manipulation by local contact

Local, deterministic manipulation of individual vortices in type 2 superconductors is challenging. The ability to control the position of individual vortices is necessary in order to study how vortices interact with each other, with the lattice, and with other magnetic objects. Here, we present a protocol for vortex manipulation in thin superconducting films by local contact, without applying current or magnetic field. Vortices are imaged using a scanning superconducting quantum interference device (SQUID), and vertical stress is applied to the sample by pushing the tip of a silicon chip into the sample, using a piezoelectric element. Vortices are moved by tapping the sample or sweeping it with the silicon tip. Our method allows for effective manipulation of individual vortices, without damaging the film or affecting its topography. We demonstrate how vortices were relocated to distances of up to 0.8 mm. The vortices remained stable at their new location up to five days. With this method, we can control vortices and move them to form complex configurations. This technique for vortex manipulation could also be implemented in applications such as vortex based logic devices.

我们的协议是铌的两个样本，和的NbN的9个样品中数以千计的个人，以及分离涡试验成功。我们通过加热上述锝样品，并在磁场的存在下将其冷却回至4.2K时产生在同一样品新涡流。我们选择了外部磁场以实现所需涡流密度。我们在这里展示这些实验数据。这些结果已经详细通过克里门等人进行了描述。 11。 <p class="jove_content" fo:keep-together.w...

Watch this Scientific Journal Video about Scanning SQUID Study of Vortex Manipulation by Local Contact at JoVE.com

Scanning SQUID Study of Vortex Manipulation by Local Contact

We present a protocol for manipulation of individual vortices in thin superconducting films, using local mechanical contact. The method does not include applying current, magnetic field or additional fabrication steps.

由当地接触式扫描涡操纵SQUID研究

Local, deterministic manipulation of individual vortices in type 2 superconductors is challenging. The ability to control the position of individual ...

scanning-squid-study-of-vortex-manipulation-by-local-contact

Universidad San Sebastian

Research

JoVE Journal

Engineering

6.8K 次观看.  Bar-Ilan University. We present a protocol for manipulation of individual vortices in thin superconducting films, using local mechanical contact. The method does not include applying current, magnetic field or additional fabrication steps. 

视频: Scanning SQUID Study of Vortex Manipulation by Local Contact

Quantitatively Measuring In situ Flows using a Self-Contained Underwater Velocimetry Apparatus (SCUVA)

The ability to directly measure velocity fields in a fluid environment is necessary to provide empirical data for studies in fields as diverse as oceanography, ecology, biology, and fluid mechanics. Field measurements introduce practical challenges such as environmental conditions, animal availability, and the need for field-compatible measurement techniques. To avoid these challenges, scientists typically use controlled laboratory environments to study animal-fluid interactions. However, it is reasonable to question whether one can extrapolate natural behavior (i.e., that which occurs in the field) from laboratory measurements. Therefore, in situ quantitative flow measurements are needed to accurately describe animal swimming in their natural environment.
We designed a self-contained, portable device that operates independent of any connection to the surface, and can provide quantitative measurements of the flow field surrounding an animal. This apparatus, a self-contained underwater velocimetry apparatus (SCUVA), can be operated by a single scuba diver in depths up to 40 m. Due to the added complexity inherent of field conditions, additional considerations and preparation are required when compared to laboratory measurements. These considerations include, but are not limited to, operator motion, predicting position of swimming targets, available natural suspended particulate, and orientation of SCUVA relative to the flow of interest. The following protocol is intended to address these common field challenges and to maximize measurement success.

Quantitatively Measuring In situ Flows using a Self-Contained Underwater Velocimetry Apparatus SCUVA

This protocol provides instructions on how to use a self-contained underwater velocimetry apparatus (SCUVA), which is designed for quantification of in situ animal-generated flows. In addition, this protocol addresses challenges posed by field conditions, and includes operator motion, predicting position of animals, and orientation of SCUVA.

定量测量原位流动，使用一个自包含的水下测速仪（SCUVA）

The ability to directly measure velocity fields in a fluid environment is necessary to provide empirical data for studies in fields as diverse as ...

科研

生物工程

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

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

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

粒子粒子相互作用采用胶体探针纳米显微定量和定性检查

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

化学

Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing technology is used to fabricate particles with slender arms connected at a common center. Shapes explored are crosses (two perpendicular rods), jacks (three perpendicular rods), triads (three rods in triangular planar symmetry), and tetrads (four arms in tetrahedral symmetry). Methods for producing on the order of 10,000 fluorescently dyed particles are described. Time-resolved measurements of their orientation and solid-body rotation rate are obtained from four synchronized videos of their motion in a turbulent flow between oscillating grids with R&#955; = 91. In this relatively low-Reynolds number flow, the advected particles are small enough that they approximate ellipsoidal tracer particles. We present results of time-resolved 3D trajectories of position and orientation of the particles as well as measurements of their rotation rates.

We use 3D printing to fabricate anisotropic particles in the shapes of jacks, crosses, tetrads, and triads, whose alignments and rotations in turbulent fluid flow can be measured from multiple simultaneous video images.

测量的方向和旋转速率方法3D打印在湍流颗粒

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing ...

工程学

Hand Controlled Manipulation of Single Molecules via a Scanning Probe Microscope with a 3D Virtual Reality Interface

Considering organic molecules as the functional building blocks of future nanoscale technology, the question of how to arrange and assemble such building blocks in a bottom-up approach is still open. The scanning probe microscope (SPM) could be a tool of choice; however, SPM-based manipulation was until recently limited to two dimensions (2D). Binding the SPM tip to a molecule at a well-defined position opens an opportunity of controlled manipulation in 3D space. Unfortunately, 3D manipulation is largely incompatible with the typical 2D-paradigm of viewing and generating SPM data on a computer. For intuitive and efficient manipulation we therefore couple a low-temperature non-contact atomic force/scanning tunneling microscope (LT NC-AFM/STM) to a motion capture system and fully immersive virtual reality goggles. This setup permits &#34;hand controlled manipulation&#34; (HCM), in which the SPM tip is moved according to the motion of the experimenter&#39;s hand, while the tip trajectories as well as the response of the SPM junction are visualized in 3D. HCM paves the way to the development of complex manipulation protocols, potentially leading to a better fundamental understanding of nanoscale interactions acting between molecules on surfaces. Here we describe the setup and the steps needed to achieve successful hand-controlled molecular manipulation within the virtual reality environment.

We demonstrate the precise manipulation of individual organic molecules on a metal surface with the tip of a scanning probe microscope driven in 3D by the experimenter's hand using a motion capture system and fully immersive virtual reality goggles.

通过手扫描探针显微镜用三维虚拟现实接口控制单分子的操作

Considering organic molecules as the functional building blocks of future nanoscale technology, the question of how to arrange and assemble such building ...

Investigating the Three-dimensional Flow Separation Induced by a Model Vocal Fold Polyp

The fluid-structure energy exchange process for normal speech has been studied extensively, but it is not well understood for pathological conditions. Polyps and nodules, which are geometric abnormalities that form on the medial surface of the vocal folds, can disrupt vocal fold dynamics and thus can have devastating consequences on a patient&#39;s ability to communicate. Our laboratory has reported particle image velocimetry (PIV) measurements, within an investigation of a model polyp located on the medial surface of an in&#160;vitro driven vocal fold model, which show that such a geometric abnormality considerably disrupts the glottal jet behavior. This flow field adjustment is a likely reason for the severe degradation of the vocal quality in patients with polyps. A more complete understanding of the formation and propagation of vortical structures from a geometric protuberance, such as a vocal fold polyp, and the resulting influence on the aerodynamic loadings that drive the vocal fold dynamics, is necessary for advancing the treatment of this pathological condition. The present investigation concerns the three-dimensional flow separation induced by a wall-mounted prolate hemispheroid with a 2:1 aspect ratio in cross flow, i.e. a model vocal fold polyp, using an oil-film visualization technique. Unsteady, three-dimensional flow separation and its impact of the wall pressure loading are examined using skin friction line visualization and wall pressure measurements.

Vocal fold polyps can disrupt vocal fold dynamics and thus can have devastating consequences on a patient&#39;s ability to communicate. Three-dimensional flow separation induced by a wall-mounted model polyp and its impact on the wall pressure loading are examined using particle image velocimetry, skin friction line visualization, and wall pressure measurements.

研究模型声乐折叠聚合物引起的三维流量分离

The fluid-structure energy exchange process for normal speech has been studied extensively, but it is not well understood for pathological conditions. ...

Visualization of Flow Field Around a Vibrating Pipeline Within an Equilibrium Scour Hole

An experimental method is presented in this paper to facilitate visualization of the detailed flow fields and determination of the near-boundary shear and normal stresses within an equilibrium scour hole induced by a vibrating pipeline. This method involves the implementation of a pipeline vibration system in a straight flume, a time-resolved particle image velocimetry (PIV) system for pipeline displacement tracking and flow fields measurements. The displacement time-series of the vibrating pipeline are obtained by using the cross-correlation algorithms. The steps for processing raw particle laden images obtained by using the time-resolved PIV are described. The detailed instantaneous flow fields around the vibrating pipeline at different vibrating phases are calculated by using a multiple-time-interval cross-correlation algorithm to avoid displacement bias error in the flow regions with a large velocity gradient. By applying the wavelet transform technique, the captured images that have the same vibrating phase are accurately cataloged before the phase-averaged velocity fields are obtained. The key advantages of the flow measurement technique described in this paper are that it has a very high temporal and spatial resolution and can be simultaneously used to obtain the pipeline dynamics, flow fields, and near-boundary flow stresses. By using this technique, more in-depth studies of the 2-dimensional flow field in a complex environment, such as that around a vibrating pipeline, can be conducted to better understand the associated sophisticated scour mechanism.

The goal of the protocol is to enable visualization of the detailed flow fields and determination of the near-boundary shear and normal stresses within an equilibrium scour hole induced by a vibrating pipeline.

平衡闪烁孔内振动管道周围流动场的可视化

An experimental method is presented in this paper to facilitate visualization of the detailed flow fields and determination of the near-boundary shear and ...

环境科学

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

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

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

用透射显微技术制备氮化硅薄膜磁性纳米结构的研究

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

Direct Force Measurements of Subcellular Mechanics in Confinement using Optical Tweezers

During the development of a multicellular organism, a single fertilized cell divides and gives rise to multiple tissues with diverse functions. Tissue morphogenesis goes in hand with molecular and structural changes at the single cell level that result in variations of subcellular mechanical properties. As a consequence, even within the same cell, different organelles and compartments resist differently to mechanical stresses; and mechanotransduction pathways can actively regulate their mechanical properties. The ability of a cell to adapt to the microenvironment of the tissue niche thus is in part due to the ability to sense and respond to mechanical stresses. We recently proposed a new mechanosensation paradigm in which nuclear deformation and positioning enables a cell to gauge the physical 3D environment and endows the cell with a sense of proprioception to decode changes in cell shape. In this article, we describe a new method to measure the forces and material properties that shape the cell nucleus inside living cells, exemplified on adherent cells and mechanically confined cells. The measurements can be performed non-invasively with optical traps inside cells, and the forces are directly accessible through calibration-free detection of light momentum. This allows measuring the mechanics of the nucleus independently from cell surface deformations and allowing dissection of exteroceptive and interoceptive mechanotransduction pathways. Importantly, the trapping experiment can be combined with optical microscopy to investigate the cellular response and subcellular dynamics using fluorescence imaging of the cytoskeleton, calcium ions, or nuclear morphology. The presented method is straightforward to apply, compatible with commercial solutions for force measurements, and can easily be extended to investigate the mechanics of other subcellular compartments, e.g., mitochondria, stress-fibers, and endosomes.

Here, we present a protocol to investigate the intracellular mechanical properties of isolated embryonic zebrafish cells in three-dimensional confinement with direct force measurement by an optical trap.

使用光学镊子测量禁闭中的亚细胞力学的直接力

During the development of a multicellular organism, a single fertilized cell divides and gives rise to multiple tissues with diverse functions. Tissue ...

发育生物学

Using a Microfluidics Device for Mechanical Stimulation and High Resolution Imaging of C. elegans

One central goal of mechanobiology is to understand the reciprocal effect of mechanical stress on proteins and cells. Despite its importance, the influence of mechanical stress on cellular function is still poorly understood. In part, this knowledge gap exists because few tools enable simultaneous deformation of tissue and cells, imaging of cellular activity in live animals, and efficient restriction of motility in otherwise highly mobile model organisms, such as the nematode Caenorhabditis elegans. The small size of C. elegans makes them an excellent match to microfluidics-based research devices, and solutions for immobilization have been presented using microfluidic devices. Although these devices allow for high-resolution imaging, the animal is fully encased in polydimethylsiloxane (PDMS) and glass, limiting physical access for delivery of mechanical force or electrophysiological recordings. Recently, we created a device that integrates pneumatic actuators with a trapping design that is compatible with high-resolution fluorescence microscopy. The actuation channel is separated from the worm-trapping channel by a thin PDMS diaphragm. This diaphragm is deflected into the side of a worm by applying pressure from an external source. The device can target individual mechanosensitive neurons. The activation of these neurons is imaged at high-resolution with genetically-encoded calcium indicators. This article presents the general method using C. elegans strains expressing calcium-sensitive activity indicator (GCaMP6s) in their touch receptor neurons (TRNs). The method, however, is not limited to TRNs nor to calcium sensors as a probe, but can be expanded to other mechanically-sensitive cells or sensors.

Using a Microfluidics Device for Mechanical Stimulation and High Resolution Imaging of C. elegans

New tools for mechanobiology research are needed to understand how mechanical stress activates biochemical pathways and elicits biological responses. Here, we showcase a new method for selective mechanical stimulation of immobilized animals with a microfluidic trap allowing high-resolution imaging of cellular responses.

利用微流体装置进行机械刺激和高分辨率成像的研究C.线虫

One central goal of mechanobiology is to understand the reciprocal effect of mechanical stress on proteins and cells. Despite its importance, the ...

神经科学

Visualizing Membrane Ruffle Formation using Scanning Electron Microscopy

Membrane ruffling is the formation of motile plasma membrane protrusions containing a meshwork of newly polymerized actin filaments. Membrane ruffles may form spontaneously or in response to growth factors, inflammatory cytokines, and phorbol esters. Some of the membrane protrusions may reorganize into circular membrane ruffles that fuse at their distal margins and form cups that close and separate into the cytoplasm as large, heterogeneous vacuoles called macropinosomes. During the process, ruffles trap extracellular fluid and solutes that internalize within macropinosomes. High-resolution scanning electron microscopy (SEM) is a commonly used imaging technique to visualize and quantify membrane ruffle formation, circular protrusions, and closed macropinocytic cups on the cell surface. The following protocol describes the cell culture conditions, stimulation of the membrane ruffle formation in vitro, and how to fix, dehydrate, and prepare cells for imaging using SEM. Quantification of membrane ruffling, data normalization, and stimulators and inhibitors of membrane ruffle formation are also described. This method can help answer key questions about the role of macropinocytosis in physiological and pathological processes, investigate new targets that regulate membrane ruffle formation, and identify yet uncharacterized physiological stimulators as well as novel pharmacological inhibitors of macropinocytosis.

Macropinocytosis is a highly conserved endocytic process initiated by the formation of F-actin-rich sheet-like membrane projections, also known as membrane ruffles. Increased rate of macropinocytotic solute internalization has been implicated in various pathological conditions. This protocol presents a method to quantify membrane ruffle formation in vitro using scanning electron microscopy.

使用扫描电子显微镜可视化膜褶皱形成

Membrane ruffling is the formation of motile plasma membrane protrusions containing a meshwork of newly polymerized actin filaments. Membrane ruffles may ...