우리는 초전도 필름을 제공하는 바 - 일란 대학의 A. Sharoni 감사합니다. 이 연구는 유럽 연구위원회 그랜트 ERC-2014-STG- 639792에 의해 지원되었다, 마리 퀴리 경력 통합 그랜트 FP7-PEOPLE-2012-CIG-333799, 이스라엘 과학 재단 그랜트 ISF-13분의 1,102.

사형 SQUID 시스템에 1. <ol><li> 칩 9, 10, 스틱 슬립 거친 모션 스테이지, 미세 운동을위한 압전 기반 스캐너 제조 된 SQUID 센서를 포함하는 주사 SQUID 시스템을 사용합니다. 그림 1을 참조하십시오. </li><li> 픽업 루프 주위 코너에 오징어 칩을 폴란드어. 칩의 재료는 줄곧 픽업 루프를 제거 할 필요가있다. <ol><li> 부드럽게 5 μm의 0.5 비자 연마 종이를 사용하여 SQUID을 연마. 주 : 연마 단계 이후 픽업 루프 시료와 근접하거나 접촉 할 수있다. </li></ol></li></ol> 직류 (DC) 스퍼터링 니오븀 (Nb) 중 1 종 이상 박막 증착 2. <ol><li> 기판을 얻습니다. 본 연구에서는, 산화 규소와 500nm의 붕소 도핑 된 실리콘 기판을 사용한다. 그러한 된 SrTiO3 및 산화 마그네슘과 같은 다른 기판이 가능합니다. </li><li> 기본 pressu 도달챔버 10-7 토르의 재. 프리 스퍼터를 10 분 동안 1.8 Å / s의 증착 속도 2.4 mTorr의 압력에서 아르곤 환경에서 99.95 % Nb를 대상으로 상온에서 증착 챔버. 챔버베이스 압력 미만 10-7 Torr의 경우 증착 프로세스에만 시작할 수 있습니다. 압력은 미리 스퍼터링 단계를 더 반복됩니다. </li><li> 챔버에서 기판을 배치합니다. </li><li> 1.8 Å / s의 증착 속도 2.4 mTorr의 압력에서 아르곤 환경에서는 99.95 % Nb를 타겟으로부터, 실온에서 스퍼터링 법에 의해 예금 Nb를 박막. </li></ol> 3. 샘플 팁 정렬 <ol><li> 와류를 이동할 때, 칩의 선단이 시료와 접촉하도록이 단계에서, 샘플 센서 칩을 정렬. 이를 달성하기 위해, 적어도 39 °의 배향 각을 사용한다. </li><li> 유전체 층으로 도전 접시에 유연한 캔틸레버 접착제. 그 후, SQUID 치 접착제캔틸레버에 페이지. 캔틸레버와 고정 플레이트 사이의 정전 용량은 샘플과 적용 스트레스의 정도와의 접촉을 결정합니다. </li><li> 현미경에로드 샘플. 지정된 샘플 샘플을 접착제하면 광택 또는 페이스트를 사용하여 마운트합니다. Z 축 압전 소자 (그림 1a)에 마운트 접착제. </li><li> 컨트롤러에 스틱 슬립 거친 모션 시스템을 연결합니다. </li><li> 전면과 칩의 측면 - 두 개의 각도에서 광학 영상을 설정합니다. 상기 칩의 전면과 측면의 하나에 관한 번역 단계에 배치이 망원경을 사용합니다. </li><li> 반사 센서의 샘플에 표시되도록 Z 스틱 슬립 거친 움직임 스테이지를 사용하여 상기 센서로부터 1 ㎛의 거리에 샘플을 이동. 참고 : SQUID 문제를 야기 할 수 있습니다이 단계에서 시료와 센서 사이에 문의하십시오. </li><li> 는 S의 손상을 방지하기 위해 Z 스틱 슬립 거친 움직임 스테이지를 사용하여 1mm 떨어져 센서 - 0.5 샘플 이동한 번 씹는 분량. </li><li> 동일한 전면 각도를 얻을 수있는 맞춤 나사 (그림 1a)를 회전 (즉, 그림 1C에서와 같이 칩의 팁의 측면은, 그것의 반사로 만들 각도). </li><li> 센서로부터 1 ㎛의 거리에 샘플을 이동합니다. 각도를 확인하고 필요한 경우 단계 3.7 및 3.8를 반복합니다. </li><li> 센서와 샘플 (그림 1D) 사이의 4 도의 각도를 얻기 위해 맞춤 나사를 돌립니다. 칩의 끝이 시료와 접촉하는 부분입니다 있는지 확인합니다. </li></ol> 4. 측정 <ol><li> 4 K의 냉각 시스템에 스캐닝 헤드 (도 1a)을로드. 주 : 스캐닝 헤드는 콜드 플레이트에 접속되고, 진공 캔으로 둘러싸인한다. 외부 자기장을 (여러 가우스의 낮은 필드는이 연구에 충분) 적용하기위한 캔 주위에 코일 배선. 뮤 금속 방패이 설정을 커버. </li><li> MAGNE의 존재 쿨TIC 필드 현미경을 둘러싸는 코일을 통해 전류를인가하여. 원하는 와류 밀도를 달성하기 위해주의하여 전계 강도를 선택. 재사용 대기 시간 필드를 계산하는 1Φ 0 = 20.7 G / μm의 2를 사용합니다. 예를 들어, 10 ㎛의 10 ㎛에 의해 영역 (10)의 와류에 대한, 2.07 G. 적용 </li><li> (10 K 이상, Nb를 들어 열) 초전도 전이 온도보다 새로운 와류 밀도 열 샘플 변화. 새 필드를 적용합니다. </li><li> 4.2 K. 쿨 샘플 </li><li> 자기장을 끕니다. SQUID를 켭니다. </li><li> 스틱 슬립 조대 모션 시스템을 사용하여 SQUID에 가까운 샘플을 이동. <ol><li> 오징어 칩에 가까운 샘플을 이동 Z-스틱 슬립 큐브 증가하고 전압을 적용합니다. </li><li> 용량 다리 (일반적으로 0.1 V)를 사용하여 캐패시턴스를 판독 캔틸레버와 플레이트 사이에 전압을인가한다. </li><li> Z 축 압전 소자에 전압을 스윕. 캔틸레버와 작은지면 사이의 정전 용량을 측정이자형. 정전 용량에 큰 변화가 발생하는 경우, 샘플은 SQUID 칩과 접촉한다. </li><li> 샘플 칩과의 접촉을하지 않은 경우, 단계를 반복 4.6.1-4.6.3 접촉이 관찰 될 때까지. </li><li> 선택 사항 : 해당 연락처가 낮은 전압 (- 0 Z 압전에 적용 10 V)에서 발생 있도록 팁과 시료 사이의 간격을 조정하는 과정 모션을 사용합니다. </li><li> 접촉이되면 반복 표면의 경사 각도를 결정하기 위해 상기 센서에 대하여 샘플의 평면을 정의하기 위해 여러 위치 4.6.2-4.6.3 단계. </li></ol></li><li> 센서의 샘플에 대하여 이동하기 위해, X와 Y의 압전 소자에 전압을 스윕. 와류 분포를 매핑하기 위해, 팁과 시료 사이의 접촉없이 상기 샘플 일정한 높이에서 스캔. X 및 Y 위치에 따른 압전 Z상의 전압을 변화시킴으로써 일정한 스캔 높이를 달성하고, 4.6에 규정되는 평면이다. </li><li> 소용돌이를 선택하고 arou 검색ND는 정확하게 중심의 위치를 ​​결정한다. 와류 위치하지 접점 때문에, SQUID의 픽업 루프에 대하여 유의. </li><li> SQUID의 전원을 끕니다. </li><li> 다음 와류 중심 Z 축 피에조 및 중 탭에 접지 전압보다 큰 전압을인가하거나, 원하는 위치에 샘플을 천천히 (시료와 접촉하는) 센서를 드래그하여 소용돌이 청소. 와류는 탭으로 또는 주사 방향으로 이동합니다. 일반적인 값은 2-5이다 V.인가 Z 압전 전압에 추가 </li><li> SQUID를 켭니다. </li><li> 접촉없이 일정한 높이에서 다시 이미지는 소용돌이의 새 위치를 찾습니다. </li></ol>

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The authors have nothing to disclose.

소용돌이의 성공적인 조작은 몇 가지 중요한 단계에 따라 달라집니다. 이 칩의 끝이 샘플과 접촉을 할 첫 번째가 될 것 같은 것이, 각도 센서를 정렬하는 것이 중요합니다. 둘째, 시료에 가해지는 힘이 칩에 장착 된 칸틸 레버의 기계적 특성에 의해 결정된다는 점에 유의하는 것이 중요하다. 탄성 체제에 가해지는 힘은 후크의 법칙에 의하면, 구부러짐, (X)에 비례한다 : F = -kx <p class="jove_con...

소용돌이는 외부 자기장의 존재 제 2 형 초전도체에 형성된 나노 크기의 자성이다. 결함 무료 샘플에서 소용돌이 자유롭게 이동할 수 있습니다. 그러나, 와류에 대한 정력적으로 유리한 감소 초전도의 지역에 소재 결과에 다른 결함. 소용돌이는이 지역 또한 고정 사이트로 알려져을 장식하는 경향이있다. 이 경우에, 와류를 이동 시키는데 필요한 힘은 닝힘보다 커야한다. 이러한 와류 밀도 상호 작용 강도 및 범위 등 와류의 특성을 쉽게 외부 필드, 온도 나 시료의 형상에 의해 결정될 수있다. 이들 특성을 조절하는 기능들을 전자 응용 1,2 쉽게 조정될 수 응집 물질 동작뿐만 아니라 적합한 후보 좋은 모델 시스템 만든다. 각각의 와류의 위치 제어는 LO의 설계에 필수적인학적 요소입니다. 자성 나노 입자의 기계적 제어 전에 달성했다. Kalisky 등은. 최근 복합 산화물 인터페이스 3 강자성 패치에 대한 지역 기계적 응력의 영향을 연구하기 위해 스캔 초전도 양자 간섭 장치 (SQUID)를 사용했다. 이러한 과정에서 최대 1 μN의 힘을 적용하는 시료로 SQUID의 팁을 누르는 접촉 주사하여 패치의 방향을 변경할 수 있었다. 우리는 소용돌이를 이동하기 위해 우리의 프로토콜에서 유사한 방법을 사용했다. 선회 조작 기존 연구에서 모션 따라서 로렌츠 힘 (4, 5), (6) 생성, 샘플에 전류를인가함으로써 달성되었다. 이 방법은 효과적이지만, 로컬없고, 단일 소용돌이를 조절하기 위해 추가의 제조가 요구된다. 소용돌이는 manip 될 수 있습니다자기력 현미경 (MFM)으로 또는 SQUID 계자 코일 (7), (8), 예를 들면 외부 자계를인가함으로써 ulated. 이 방법은 효과적이고 로컬이지만, 이러한 툴에 의해 가해지는 힘이 작기 만 초전도체의 임계 온도에 가까운 고온에서 피닝 힘을 극복 할 수있다. 우리의 프로토콜은 샘플의 추가 가공없이 낮은 온도 (4 K)에 효과적, 지역 조작 할 수 있습니다. 우리 SQUID 주사 현미경을 사용하여 화상 와류. 센서는 구석으로 연마하고 유연한 캔틸레버에 접착되어있는 실리콘 칩 상에 제조된다. 캔틸레버는 표면의 정전 용량 검출에 사용된다. 접점은 칩의 선단에 위치하도록 상기 칩은 샘플 각도로 배치된다. 우리는 샘플에 칩을 밀어 최대 2 μN의 힘을 적용한다. 우리는 압전 소자에 의한 SQUID에 샘플 상대적으로 이동합니다. 우리는 이동소용돌이 옆에, 또는 그것을 청소 소용돌이를 터치하여 실리콘 팁을 탭하여 와류.

<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.

우리의 프로토콜은 성공적으로 Nb를 두 샘플 및 NBN의 구 샘플에서 개인, 잘 분리 와류의 수천 시험 하였다. 우리는 Tc를 상기 샘플을 가열하고, 자기장의 존재하에 다시 4.2 K까지를 ​​냉각하여 동일한 샘플 새로운 와류를 생성한다. 우리가 원하는 선회 밀도를 달성하기 위해, 외부 자계를 선택했다. 우리는 여기서이 실험에서 데이터가 표시됩니다. 이러한 결과는 크리 멘 ...

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.

현지 연락처로 소용돌이 조작의 SQUID 연구를 스캔

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 조회수.  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. 

비디오: 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.

양적 측정 현장에서</em독립적인 수중 Velocimetry 장치 (SCUVA)을 사용하여> 흐름

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

연구

생체공학

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.

콜로이드 프로브 Nanoscopy을 사용하여 입자 간 상호 작용의 양적 및 질적 시험

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

화학

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.

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

공학

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.

손 3D 가상 현실 인터페이스와 스캐닝 프로브 현미경을 통해 단일 분자의 조작을 제어

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.

모델 보컬 폴드 폴립에 의해 유도된 3차원 유동 분리 조사

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.

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

환경과학

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.

자기 소용돌이 연구 전송 현미경 검사 법 기술을 사용 하 여 실리콘 질 화 막에 자석 Nanostructures의 제조

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.

광학 핀셋을 사용하여 감금된 세포 전 역학의 직접 힘 측정

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

발생학

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.

기계적 자극 및 높은 해상도 C. 선 충 의 이미징에 대 한 마이크로 장치를 사용 하 여

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

신경과학

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.

주사 전자 현미경을 이용한 멤브레인 러플 형성 시각화

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