저자는 그림 1D에 표시된 3D 구조에 대한 단면 이미지를 제공하기 위해 어 바나 - 샴페인 일리노이 대학에서 요셉 Muskin와 매튜 라 구사 감사드립니다.

1. 성 예비 중합체 솔루션의 준비 <ol><li> 믹스 폴리 (에틸렌 글리콜) diacrylate (PEG-DA) (평균 분자량 ~ 575, 시그마 - 알드리치)과 1시 2분 체중의 비율로 폴리 (에틸렌 글리콜) (PEG) (평균 분자량 ~ 200, 시그마 - 알드리치). </li><li> 0.67 %의 중량을 추가합니다. 사진 기자 (Phenylbis (2,4,6-trimethylbenzoyl) phosphine 산화물, 시그마 - 알드리치). 솔루션은이 시점부터 어두운 환경에서 보관해야합니다. </li><li> 0.05 % 중량을 추가합니다. 사진 흡수 (수단 I, 시그마 - 알드리치). </li><li> 자기 교반기를 사용하여 실온에서 24 시간 동안 솔루션을 섞는다. </li></ol> 2. 디지털 데이터 프로젝터를 사용하여 데스크탑 3D 프린터 설정 <ol><li> 평면 안정적인 위치에 디지털 데이터 프로젝터를 배치 및 Microsoft PowerPoint가 설치되어있는 컴퓨터에 연결합니다. </li><li> 디지털 프로젝터의 빔 출력 렌즈 앞에 볼록 렌즈를 오른쪽으로 놓습니다. 프로에서 약 10cm 떨어진 곳에 초점 비행기를 만들기 위해 볼록 렌즈를 선택jector. (광 해상도가 짧은 초점 길이 있지만, 광학 구성 요소에 대한 여유 공간을 예약 한 요구에 렌즈에 대한 작아집니다.) </li><li> 곧장 빔을 직접하기 위해 45 ° 각도에서 빔 경로에있는 볼록 렌즈 후에 거울을 배치합니다. </li><li> 예상 빔의 초점 평면에서 샘플 홀더를 놓으십시오. 샘플 홀더는 샘플 홀더의 수직 위치를 제어하는​​하여 선형 단계에 부착해야합니다. </li><li> 샘플 홀더 아래에 수지 욕조를 배치합니다. </li></ol> 3. 젤 튜브의 설계 및 제작 <ol><li> 직경, 벽 두께, 제조 될 수있는 젤 튜브의 높이를 확인합니다. </li><li> 겔 튜브에 대한 단면 이미지를 그립니다. 이미지는 검은 색 배경과 흰색에 있어야합니다. 마이크로 소프트 파워 포인트 슬라이드에서 이러한 이미지를 삽입합니다. </li><li> Microsoft PowerPoint에서 슬라이드 쇼를 시작하고 영상을 투사합니다. AT &amp; T를 사용하여 수직 위치를 조정하여 초점 평면에서 샘플 홀더를 배치단계를 ached. </li><li> 성 예비 중합체 솔루션을 넣어 동안 더 원치 않는 중합가 없습니다 있도록 &quot;더미&quot;검정 이미지로 전환합니다. </li><li> 수지 목욕탕 성 예비 중합체 솔루션을 넣어. 솔루션은 약간의 샘플 홀더를 포함 할 때까지 목욕탕을 입력합니다. 이제 인쇄 3D 개체에 대한 준비가되었습니다. </li><li> 첫 번째 층을 중합 할 수있는 젤 튜브의 첫 번째 단면 이미지가 포함 된 슬라이드로 전환합니다. 8 초 동안 이미지를 투영 유지하고 &quot;정전&quot;슬라이드로 전환합니다. </li><li> ¼ 회전하여 선형 무대에서 노브를 회전 샘플 홀더를 낮추 (~ 160 μm). 지금 신선한 수지 polymerized 첫 번째 층을 커버하기에 흐른다. </li><li> 절차 하나의 상단에 두 번째 층을 중합 다시 단면 영상을 투사합니다. 원하는 높이의 겔 튜브 제조 될 때까지 반복 3.6-3.8 단계를 반복합니다. </li><li> 모든 레이어가 완료되면, 레이저 blad를 사용하여주의 깊게 가공 샘플을 예비 중합체 솔루션의 샘플 홀더를 들어, 그리고 검색5. </li><li> ~ 3 시간에 아세톤에있는 샘플을 헹구고, 그때는 ~ 1 시간에 건조 할 수 있습니다. </li></ol> 4. 탄성 불안정에 의해 소정 패턴 형성 실험을 붓게 <ol><li> 투명한 유리 접시에 물 기름 듀얼 레이어 액체를 준비합니다. </li><li> 슈퍼 접착제를 사용하여 샘​​플 홀더에 건조 샘플을 첨부합니다. </li><li> 샘플이 뒤집어 져 있는데요 있도록 샘플 홀더를 뒤집기. 물 기름 액체 목욕탕에서 샘플을 빠져. 오일 층에서 물 기름 인터페이스에 샘플을 접근한다. 샘플 젤 튜브는 고정 된베이스 기판 부분은 상단 기름 층에 체재하는 동안 샘플이 물 표면에 닿을 때 팽창하기 시작한다. 이러한 방법으로, 물은 자제베이스 으러으로 완화하기 전에 샘플 팽창 수 있도록 튜브 벽에 확산 할 수 있습니다. 디지털 카메라를 사용하여 겔 튜브가 불 같은 패턴의 변화를 모니터링합니다. </li></ol>

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관심 없음 충돌이 선언 없습니다.

기판에 제약 관 히드로 겔의 팽창에 안정성은 t / H와 모드를 변형하는 것은 H / D 12에 따라 달라집니다에 따라 달라집니다. 정규화 된 두께 t / H의 다른 수준이 샘플 네 그룹 (I-IV)는 그룹 내 두꺼운 것 및 그룹 IV 더 슬림거든요, 가공되었습니다. 각 그룹은 샘플을 제가 짧게하고 샘플 IV 키도 크게되는 것과 정규화 된 높이 H / D의 다른 수준의 4 개의 샘플 (I-IV)로 구성되어 있습니다. 가공 샘플의 크기는 표 1에 표시됩니다. 그룹 III 및 IV는 버클과 팽창에 따라 변화하도록 설계되었습니다 반면, 그룹 I과 II는 붓기 동안 안정적으로 유지하도록 설계되어 있습니다. 좌굴 샘플, 버 클린 (Bucklin)에게 들어g 모드는 샘플 높이 감소한다. 그림 3A는 실험 결과를 보여줍니다. 이론은 예측에 따라, 그룹 I과 II의 샘플은 안정적 이었어요 및 그룹 III 및 IV의 샘플이 모든 탄성 불안정으로 가서 buckled 반면, 붓기에 원형 있었다. 또한, 동일한 H / D와 샘플 유사한 좌굴 모드를 표시. 그림 3B는 이론적 예측과 그룹 III 및 IV에 샘플 실험적으로 관찰 좌굴 모드를 비교합니다. 우리는 같은 H / D와 그 샘플을 볼 수에 관계없이 두께의 동일한 후 좌굴 패턴을 포즈, 그리고 그 실험 결과는 이론과 잘 동의 할 수 있습니다. 우리는 상업적으로 이용 가능한 디지털 데이터 프로젝터를 사용하여 간단한 데스크톱 3D 인쇄 시스템을 구축하는 방법을 제시한다. 제안 된 방법은 사기꾼으로 폴리머의 photocuring에 의존3D 구조를 구조체, 따라서, 모든 photocurable 폴리머는 또한까지 photoinitiator이 표시 파장 범위에 해당하는 흡광도가 같은 일반적으로 사용할 수 있습니다. 많은 상업적으로 이용 가능한 photoinitiators는 자외선 (UV) 파장을 위해 설계되었습니다 있습니다,하지만 사용 photoinitiator는 400 nm의 파장 이상에서 상대적으로 높은 흡광도가 있습니다. 3D 객체를 조작 할 수있는 쉽고 빠른 방법을 제공하는이 방법은 여기를 증명 등의 부드러운 재료 역학 등 다양한 분야에서 많은 응용 프로그램을 찾을 수 있습니다.

<table border="1"><tbody><tr><td> 시약의 이름 </td><td> 회사 </td><td> 카탈로그 번호 </td><td> 코멘트 (선택 사항) </td></tr><tr><td> 폴리 (에틸렌 글리콜) diacrylate </td><td> 시그마 - 알드리치 </td><td> 437441 </td><td> MW ~ 575 </td></tr><tr><td> 폴리 (에틸렌 글리콜) </td><td> 시그마 - 알드리치 </td><td> P3015 </td><td> MW는 200 ~ </td></tr><tr><td> phenylbis (2,4,6-trimethylbenzoyl) phosphine 산화물 </td><td> 시그마 - 알드리치 </td><td> 511447 </td><td> 사진 기자 </td></tr><tr><td> 수단 I </td><td> 시그마 - 알드리치 </td><td> 103624 </td><td> 사진 흡수 </td></tr><tr><td> 디지털 데이터 프로젝터 </td><td> 뷰소닉 </td><td> PJD6221 </td><td></td></tr><tr><td> 볼록 렌즈 </td><td> Thorlabs </td><td> LA1145 </td><td> F = 75.0 mm </td></tr><tr><td> Mirr또는 </td><td></td><td></td><td> 4 &quot;실리콘 웨이퍼 </td></tr><tr><td> 수동 단계 </td><td> Velmex </td><td> A2506DE-S2.5 </td><td></td></tr></tbody></table>

micro 3d printing using a digital projector and its application in the study of soft materials mechanics

좌굴이 기계의 고전 주제입니다. 좌굴이 오랜 주요 구조 실패 모드 1 중 하나로서 연구되어 있지만, 최근 패턴 변화에 대한 고유 한 메커니즘으로 새로운 관심을 모으고있다. 이국적인 패턴의 풍부한이 기계 불안정 2-5을 통해 형성되는 곳 자연은 예제 가득합니다. 이 우아한 메커니즘에 의해 영감을, 많은 연구는 탄성체와 hydrogels 6-11와 같은 부드러운 재료를 사용하여 패턴 생성 및 변화를 증명하고있다. 사람들이 자발적으로 외부 힘 6-10의 필요없이 다양한 패턴을 만들 기계적 불안정을 일으킬 수 있기 때문에 부종이 젤은 특히 관심이 있습니다. 최근, 우리는 프로젝션 마이크로 stereolit​​hography (PμSL), 빠른 속도로 컴퓨터 생성 3D 모델에게 내가 변환 할 수있는 3 차원 (3D) 제조 기술을 사용하여 마이크로 스케일 관 젤의 패턴을 변형에 대한 모든 권한의 시범을보고고해상도 12,13에서 n 인물 물리적 인 물체 야. 여기 제어 패턴 변화에 대한 팽창 유발 좌굴 불안정을 공부하기 위해 상업적으로 이용 가능한 디지털 데이터 프로젝터를 사용하여 단순화 PμSL 시스템을 구축 할 수있는 간단한 방법을 제시한다. 간단한 바탕 화면 3D 프린터는 오프 - 더 - 선반 디지털 데이터 프로젝터와 같은 볼록 렌즈와 거울 14 간단 광학 구성 요소를 사용 내장되어 있습니다. 3D 솔리드 모델에서 추출 단면 이미지는 레이어로 레이어 방식으로 원하는 3D 솔리드 구조로 액체 수지 polymerizing, 순서대로 감광성 수지 표면에 투영되어 있습니다. 이 간단한 구성과 쉬운 프로세스를 임의의 3D 개체를 쉽게 하위-100 μm의 해상도로 제조 될 수있다. 이 데스크탑 3D 프린터는 다양한 3D 형상을 탐험 할 수있는 좋은 기회를 제공하여 부드러운 재료 역학의 연구 잠재력을 보유하고 있습니다. 우리는 fabrica이 시스템을 사용다른 크기와 테 관 모양의 히드로 겔 구조. 기판 바닥에 고정, 관 젤이 불안정 변형을 야기 할 수 있습니다 붓기, 동안 inhomogeneous 스트레스를 개발하고 있습니다. 겔 구조 변형 받아야 할 때 다양한 물결 모양의 패턴은 튜브의 원주를 따라 나타납니다. 실험 원하는 모드의 좌굴 주변이 통제 된 방식으로 생성 할 수 있습니다 것으로 나타났습니다. 세 치수 구조 관 젤의 패턴 변화는 기계 및 재료 과학뿐만 아니라 중요한 의미를 가지고 있지만, 또한 조정할 수 matamaterials 많은 다른 새로운 분야 인치

재고품의 디지털 데이터 프로젝터를 사용하는 간단한 PμSL 시스템은 그림 1에 표시됩니다. 75mm의 초점 거리와 볼록 렌즈가 2cm로 2cm의 작은 조명 영역에 빔을 집중하고 있습니다. 광학 해상도 - 비행기의 결과는 45 μm이다. 수직 해상도는 선형 단계의 정밀 수준에 의해 결정됩니다. 이 연구를 위해 만든 구조물의 층의 두께는 160 μm이다. 각 층은 8 초 빛 조명에 대한 polymerized되었습니다. 시스템에 의해 제조 된 대표적인 3D 구조는 그림 1D에 표시됩니다. 이 객체는 PEGDA 58 층으로 구성되어 있습니다. 우리는 사진 경화 PEGDA의 히드로 겔을 준비했습니다. PEGDA의 히드로 겔의 낮은 crosslinking 따라서 큰 붓기는 성 예비 중합체 솔루션에 비 crosslinking의 PEG를 추가하여 달성되었다. 그 결과 PEGDA의 히드로 겔의 길이 - 현명한 붓기 비율이 높은 300 %의 용적 확장에 해당하는 1.5입니다. &gt; PEGDA의 히드로 겔 튜브의 집합은 설계 및 이론 (12)에 따라 조작했다. 우리는 거꾸로 샘플을 배치하고 그림 2A에 도시 된 바와 같이 상단에 기름 층으로 덮여 물을 욕조에 넣어. 차원 매개 변수에 따라 원형 튜브도 안정적으로 유지 또는 그림 2B와 같이 물결 모양 패턴으로 변환. 다른 샘플 패턴을 붓게의 다양한 종류의 디지털 카메라에 의해 캡처도 3a에 수여되었습니다. <img alt="그림 1" src="/files/ftp_upload/4457/4457fig1.jpg" /> 그림 1. 바탕 화면 프로젝션 마이크로 stereolithography 시스템 () 도식 표현 (B) 실제 시스템 구성 요소 (C) 근접 전망 (D) 대표 3D 구조를. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/4457/4457fig1large.jpg" target="_blank">큰 그림을 보려면 여기를 클릭하십시오</a> . 십t &quot;강한 : 유지 - together.within 페이지 =&quot;항상 &quot;&gt; <img alt="그림 2" src="/files/ftp_upload/4457/4457fig2.jpg" /> 그림 2. (b)는 제약 히드로 겔 튜브가 서로 다른 패턴으로 변환 붓기 히드로 겔 튜브 (A) 실험 설정. 스케일 바는 5mm를 나타냅니다. <img alt="그림 3" src="/files/ftp_upload/4457/4457fig3.jpg" /> 그림 3. () 패턴 실험을 부기 형성. 수직 축 t / H을 (따라서 안정성)을 나타냅니다, 그리고 수평 축 H / D를 (따라서 모드 좌굴) 나타냅니다. 스케일 바는 5mm를 나타냅니다. (B) 모드를 좌굴 것은 H / D에 따라 달라집니다. 실험 결과는 이론적 인 예측과 잘 동의합니다. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/4457/4457fig3large.jpg" target="_blank">큰 그림을 보려면 여기를 클릭하십시오</a> . <table border="1"><tbody><tr><td colspan="2"> 샘플 &lt;/ strong&gt;을 </td><td> D (μm) </td><td> t (μm) </td><td> H (μm) </td></tr><tr><td rowspan="4"> 나는 </td><td> 나는 </td><td> 9300 ± 420 </td><td> 760 ± 40 </td><td> 840 ± 40 </td></tr><tr><td> II </td><td> 9700 ± 420 </td><td> 1040 ± 40 </td><td> 1060 ± 40 </td></tr><tr><td> III </td><td> 9700 ± 420 </td><td> 1210 ± 40 </td><td> 1340 ± 40 </td></tr><tr><td> IV </td><td> 9700 ± 420 </td><td> 1660 ± 40 </td><td> 1680 ± 40 </td></tr><tr><td rowspan="4"> II </td><td> 나는 </td><td> 9000 ± 420 </td><td> 480 ± 40 </td><td> 880 ± 40 </td></tr><tr><td> II </td><td> 9000 ± 420 </td><tD&gt; 660 ± 40 </td><td> 1060 ± 40 </td></tr><tr><td> III </td><td> 9500 ± 420 </td><td> 740 ± 40 </td><td> 1350 ± 40 </td></tr><tr><td> IV </td><td> 9200 ± 420 </td><td> 970 ± 40 </td><td> 1650 ± 40 </td></tr><tr><td rowspan="4"> III </td><td> 나는 </td><td> 8900 ± 420 </td><td> 160 ± 40 </td><td> 790 ± 40 </td></tr><tr><td> II </td><td> 8900 ± 420 </td><td> 300 ± 40 </td><td> 1020 ± 40 </td></tr><tr><td> III </td><td> 9100 ± 420 </td><td> 380 ± 40 </td><td> 1330 ± 40 </td></tr><tr><td> IV </td><td> 9000 ± 420 </td><td> 490 ± 40 </td><td> 1630 ± 40 </td></tr><tr><td rowspan="4"> IV </td><td> 나는 </td><td> 8900 ± 420 </td><td> 140 ± 40 </td><td> 780 ± 40 </td></tr><tr><td> II </td><td> 8800 ± 420 </td><td> 190 ± 40 </td><td> 1010 ± 40 </td></tr><tr><td> III </td><td> 9300 ± 420 </td><td> 230 ± 40 </td><td> 1340 ± 40 </td></tr><tr><td> IV </td><td> 8900 ± 420 </td><td> 290 ± 40 </td><td> 1650 ± 40 </td></tr></tbody></table> 표 1. 샘플 크기는 광학 현미경으로 측정. 오류가 측정 불확실성을 나타냅니다.

Watch this Scientific Journal Video about Micro 3D Printing Using a Digital Projector and its Application in the Study of Soft Materials Mechanics at JoVE.com

Micro 3D Printing Using a Digital Projector and its Application in the Study of Soft Materials Mechanics

우리는 탄성 불안정에 의해 팽창 겔 튜브의 제어 패턴 변환을 보여줍니다. 간단한 프로젝션 마이크로 스테레오 - 리소그래피 설정은 레이어 별 레이어 방식으로 입체 고분자 구조를 조작하는 오프 - 더 - 선반 디지털 데이터 프로젝터를 사용하여 만들어졌습니다. 기계 제약 히드로 겔 튜브를 팽창하는 차원에 따라 다양한 주변 좌굴 모드를 표시합니다.

소프트 재료 역학의 연구에서 디지털 프로젝터와 응용 프로그램을 사용하여 마이크로 3D 인쇄

Buckling is a classical topic in mechanics. While buckling has long been studied as one of the major structural failure modes1, it has recently drawn new ...

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Unit 1

Equilibrium and Elasticity

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25.2K 조회수.  Massachusetts Institute of Technology. 우리는 탄성 불안정에 의해 팽창 겔 튜브의 제어 패턴 변환을 보여줍니다. 간단한 프로젝션 마이크로 스테레오 - 리소그래피 설정은 레이어 별 레이어 방식으로 입체 고분자 구조를 조작하는 오프 - 더 - 선반 디지털 데이터 프로젝터를 사용하여 만들어졌습니다. 기계 제약 히드로 겔 튜브를 팽창하는 차원에 따라 다양한 주변 좌굴 모드를 표시합니다.

비디오: Micro 3D Printing Using a Digital Projector and its Application in the Study of Soft Materials Mechanics

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do so is highly important in view of a number of applications in functional soft matter including electronics, biomedical engineering, and sensors. In the past, successful strategies to control the size and shape of supramolecular polymers typically focused on the use of templates2,3, end cappers4 or selective solvent techniques5. 
Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing electrostatic repulsive interactions on the hydrophilic rim and attractive non-covalent forces within the hydrophobic core of the polymerizing building block, we manage to create small and discrete spherical objects6,7. Increasing the salt concentration to screen the charges induces a sphere-to-rod transition. Intriguingly, this transition is expressed in an increase of cooperativity in the temperature-dependent self-assembly mechanism, and more stable aggregates are obtained. 
For our study we select a benzene-1,3,5-tricarboxamide (BTA) core connected to a hydrophilic metal chelate via a hydrophobic, fluorinated L-phenylalanine based spacer (Scheme 1). The metal chelate selected is a Gd(III)-DTPA complex that contains two overall remaining charges per complex and necessarily two counter ions. The one-dimensional growth of the aggregate is directed by &pi;-&pi; stacking and intermolecular hydrogen bonding. However, the electrostatic, repulsive forces that arise from the charges on the Gd(III)-DTPA complex start limiting the one-dimensional growth of the BTA-based discotic once a certain size is reached. At millimolar concentrations the formed aggregate has a spherical shape and a diameter of around 5 nm as inferred from 1H-NMR spectroscopy, small angle X-ray scattering, and cryogenic transmission electron microscopy (cryo-TEM). The strength of the electrostatic repulsive interactions between molecules can be reduced by increasing the salt concentration of the buffered solutions. This screening of the charges induces a transition from spherical aggregates into elongated rods with a length &gt; 25 nm. Cryo-TEM allows to visualise the changes in shape and size. In addition, CD spectroscopy permits to derive the mechanistic details of the self-assembly processes before and after the addition of salt. Importantly, the cooperativity -a key feature that dictates the physical properties of the produced supramolecular polymers- increases dramatically upon screening the electrostatic interactions. This increase in cooperativity results in a significant increase in the molecular weight of the formed supramolecular polymers in water.

The goal of this experiment is to determine and control the size, shape and stability of self-assembled discotic amphiphiles in water. For aqueous based supramolecular polymers such level of control is very difficult. We apply a strategy using both repulsive and attractive interactions. The experimental techniques applied to characterize this system are broadly applicable.

물에 Supramolecular 폴리머의 크기, 모양과 안정성을 제어

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do ...

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공학

High-resolution, High-speed, Three-dimensional Video Imaging with Digital Fringe Projection Techniques

Digital fringe projection (DFP) techniques provide dense 3D measurements of dynamically changing surfaces.&#160;Like the human eyes and brain, DFP uses triangulation between matching points in two views of the same scene at different angles to compute depth.&#160;However, unlike a stereo-based method, DFP uses a digital video projector to replace one of the cameras1. The projector rapidly projects a known sinusoidal pattern onto the subject, and the surface of the subject distorts these patterns in the camera&#8217;s field of view. Three distorted patterns (fringe images) from the camera can be used to compute the depth using triangulation.
Unlike other 3D measurement methods, DFP techniques lead to systems that tend to be faster, lower in equipment cost, more flexible, and easier to develop.&#160;DFP systems can also achieve the same measurement resolution as the camera.&#160;For this reason, DFP and other digital structured light techniques have recently been the focus of intense research (as summarized in1-5). Taking advantage of DFP, the graphics processing unit, and optimized algorithms, we have developed a system capable of 30&#160;Hz 3D video data acquisition, reconstruction, and display for over 300,000 measurement points per frame6,7.&#160;Binary defocusing DFP methods can achieve even greater speeds8.
Diverse applications can benefit from DFP techniques. Our collaborators have used our systems for facial function analysis9, facial animation10, cardiac mechanics studies11, and fluid surface measurements, but many other potential applications exist.&#160;This video will teach the fundamentals of DFP techniques and illustrate the design and operation of a binary defocusing DFP system.

This video describes the fundamentals of digital fringe projection techniques, which provide dense 3D measurements of dynamically changing surfaces.&#160;It also demonstrates the design and operation of a high-speed binary defocusing system based on these techniques.

Digital fringe projection (DFP) techniques provide dense 3D measurements of dynamically changing surfaces.&#160;Like the human eyes and brain, DFP uses ...

Synthesis and Functionalization of 3D Nano-graphene Materials: Graphene Aerogels and Graphene Macro Assemblies

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. Additionally, most reported graphene assemblies are held together through physical interactions (e.g., van der Waals forces) rather than chemical bonds, which limit their mechanical strength and conductivity. This video method details recently developed strategies to fabricate mass-producible, graphene-based bulk materials derived from either polymer foams or single layer graphene oxide. These materials consist primarily of individual graphene sheets connected through covalently bound carbon linkers. They maintain the favorable properties of graphene such as high surface area and high electrical and thermal conductivity, combined with tunable pore morphology and exceptional mechanical strength and elasticity. This flexible synthetic method can be extended to the fabrication of polymer/carbon nanotube (CNT) and polymer/graphene oxide (GO) composite materials. Furthermore, additional post-synthetic functionalization with anthraquinone is described, which enables a dramatic increase in charge storage performance in supercapacitor applications.

This video method describes the synthesis of high surface area, monolithic 3D graphene-based materials derived from polymer precursors as well as single layer graphene oxide.

합성 및 3D 나노 그래 핀 소재의 기능화 : 그래 핀 에어로젤과 그래 핀 매크로 어셈블리

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. ...

Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and non-destructively reveals the hydrogen density distribution at surfaces, at interfaces, and in the volume of solid materials with high depth resolution. The technique applies a 15N ion beam of 6.385 MeV provided by an electrostatic accelerator and specifically detects the 1H isotope in depths up to about 2 &#956;m from the target surface. Surface H coverages are measured with a sensitivity in the order of ~1013 cm-2 (~1% of a typical atomic monolayer density) and H volume concentrations with a detection limit of ~1018 cm-3 (~100 at. ppm). The near-surface depth resolution is 2-5 nm for surface-normal 15N ion incidence onto the target and can be enhanced to values below 1 nm for very flat targets by adopting a surface-grazing incidence geometry. The method is versatile and readily applied to any high vacuum compatible homogeneous material with a smooth surface (no pores). Electrically conductive targets usually tolerate the ion beam irradiation with negligible degradation. Hydrogen quantitation and correct depth analysis require knowledge of the elementary composition (besides hydrogen) and mass density of the target material. Especially in combination with ultra-high vacuum methods for in-situ target preparation and characterization, 1H(15N,&#945;&#947;)12C NRA is ideally suited for hydrogen analysis at atomically controlled surfaces and nanostructured interfaces. We exemplarily demonstrate here the application of 15N NRA at the MALT Tandem accelerator facility of the University of Tokyo to (1) quantitatively measure the surface coverage and the bulk concentration of hydrogen in the near-surface region of a H2 exposed Pd(110) single crystal, and (2) to determine the depth location and layer density of hydrogen near the interfaces of thin SiO2 films on Si(100).

We illustrate the application of 1H(15N,&#945;&#947;)12C resonant nuclear reaction analysis (NRA) to quantitatively evaluate the density of hydrogen atoms on the surface, in the volume, and at an interfacial layer of solid materials. The near-surface hydrogen depth profiling of a Pd(110) single crystal and of SiO2/Si(100) stacks is described.

핵 반응 분석과 깊이 프로파일 링을 통해 표면 및 인터페이스 레이어 및 대량 재료의 수소 농도의 정량화

Nuclear reaction analysis (NRA) via the resonant 1H(15N,&#945;&#947;)12C reaction is a highly effective method of depth profiling that quantitatively and ...

Wicking Tests for Unidirectional Fabrics: Measurements of Capillary Parameters to Evaluate Capillary Pressure in Liquid Composite Molding Processes

During impregnation of a fibrous reinforcement in liquid composite molding (LCM) processes, capillary effects have to be understood in order to identify their influence on void formation in composite parts. Wicking in a fibrous medium described by the Washburn equation was considered equivalent to a flow under the effect of capillary pressure according to the Darcy law. Experimental tests for the characterization of wicking were conducted with both carbon and flax fiber reinforcement. Quasi-unidirectional fabrics were then tested by means of a tensiometer to determine the morphological and wetting parameters along the fiber direction. The procedure was shown to be promising when the morphology of the fabric is unchanged during capillary wicking. In the case of carbon fabrics, the capillary pressure can be calculated. Flax fibers are sensitive to moisture sorption and swell in water. This phenomenon has to be taken into account to assess the wetting parameters. In order to make fibers less sensitive to water sorption, a thermal treatment was carried out on flax reinforcements. This treatment enhances fiber morphological stability and prevents swelling in water. It was shown that treated fabrics have a linear wicking trend similar to those found in carbon fabrics, allowing for the determination of capillary pressure.

An experimental method to measure geometrical parameters and the apparent advancing contact angles describing capillary wicking in unidirectional synthetic and natural fabrics is proposed. These parameters are mandatory for the determination of the capillary pressures that must be taken into account for liquid composite molding (LCM) applications.

During impregnation of a fibrous reinforcement in liquid composite molding (LCM) processes, capillary effects have to be understood in order to identify ...

Challenges in Rheological Characterization of Highly Concentrated Suspensions &#8212; A Case Study for Screen-printing Silver Pastes

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the manifold requirements during processing and application of such complex fluids. In this investigation, measuring protocols for a conclusive assessment of different process relevant rheological parameters have been evaluated. This includes the determination of yield stress, viscosity, wall slip velocity, structural recovery after large deformation and elongation at break as well as tensile force during filament stretching.
The importance of concomitant video recordings during parallel-plate rotational rheometry for a significant determination of rheological quantities is demonstrated. The deformation profile and flow field at the sample edge can be determined using appropriate markers. Thus, measurement parameter settings and plate roughness values can be identified for which yield stress and viscosity measurements are possible. Slip velocity can be measured directly and measuring conditions at which plug flow, shear banding or sample spillover occur can be identified clearly. 
Video recordings further confirm that the change in shear moduli observed during three stage oscillatory shear tests with small deformation amplitude in stage I and III but large oscillation amplitude in stage II can be directly attributed to structural break down and recovery. For the pastes investigated here, the degree of irreversible, shear-induced structural change increases with increasing deformation amplitude in stage II until a saturation is reached at deformations corresponding to the crossover of G' and G'', but the irreversible damage is independent of the duration of large amplitude shear. 
A capillary breakup elongational rheometer and a tensile tester have been used to characterize deformation and breakup behavior of highly filled pastes in uniaxial elongation. Significant differences were observed in all experiments described above for two commercial screen-printing silver pastes used for front side metallization of Si-solar cells.

A protocol for a robust and application relevant rheological characterization of highly concentrated suspensions is presented. Silver pastes used for screen-printing application in solar cell production are employed as model systems.

고농도 현탁액의 유변학 적 특성에 도전 - 스크린 인쇄 실버 페이스트에 대한 사례 연구

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the ...

A Soft Tooling Process Chain for Injection Molding of a 3D Component with Micro Pillars

The purpose of this paper is to present the method of a soft tooling process chain employing Additive Manufacturing (AM) for fabrication of injection molding inserts with micro surface features. The Soft Tooling inserts are manufactured by Digital Light Processing (vat photo polymerization) using a photopolymer that can withstand relatively high temperaturea. The part manufactured here has four tines with an angle of 60&#176;. Micro pillars (&#216;200 &#181;m, aspect ratio of 1) are arranged on the surfaces by two rows. Polyethylene (PE) injection molding with the soft tooling inserts is used to fabricate the final parts. This method demonstrates that it is feasible to obtain injection-molded parts with microstructures on complex geometry by additive manufactured inserts. The machining time and cost is reduced significantly compared to conventional tooling processes based on computer numerical control (CNC) machining. The dimensions of the micro features are influenced by the applied additive manufacturing process. The lifetime of the inserts determines that this process is more suitable for pilot production. The precision of the inserts production is limited by the additive manufacturing process as well.

A protocol for fabricating injection molding inserts for complex geometry with micro features on surfaces employing Additive Manufacturing (AM) is presented.

마이크로 3D 부품의 사출 성형에 대 한 부드러운 금형 프로세스 체인 기둥

The purpose of this paper is to present the method of a soft tooling process chain employing Additive Manufacturing (AM) for fabrication of injection ...

Studying Large Amplitude Oscillatory Shear Response of Soft Materials

We investigate the sequence of physical processes exhibited during large amplitude oscillatory shearing (LAOS) of polyethylene oxide (PEO) in dimethyl sulfoxide (DMSO) and xanthan gum in water &#8212; two concentrated polymer solutions used as viscosifiers in foods, enhanced oil recovery, and soil remediation. Understanding the nonlinear rheological behavior of soft materials is important in the design and controlled manufacturing of many consumer products. It is shown how the response to LAOS of these polymer solutions can be interpreted in terms of a clear transition from linear viscoelasticity to viscoplastic deformation and back again during a period. The LAOS results are analyzed via the fully quantitative Sequence of Physical Processes (SPP) technique, using free MATLAB-based software. A detailed protocol of performing a LAOS measurement with a commercial rheometer, analyzing nonlinear stress responses with the freeware, and interpreting physical processes under LAOS is presented. It is further shown that, within the SPP framework, a LAOS response contains information regarding the linear viscoelasticity, the transient flow curves, and the critical strain responsible for the onset of nonlinearity.

We present a detailed protocol outlining how to perform nonlinear oscillatory shear rheology on soft materials, and how to run the SPP-LAOS analysis to understand the responses as a sequence of physical processes.

부드러운 재료의 큰 진폭 진동 전단 응답 공부

We investigate the sequence of physical processes exhibited during large amplitude oscillatory shearing (LAOS) of polyethylene oxide (PEO) in dimethyl ...

Multimodal 3D Printing of Phantoms to Simulate Biological Tissue

Biomedical optical imaging is playing an important role in diagnosis and treatment of various diseases. However, the accuracy and the reproducibility of an optical imaging device are greatly affected by the performance characteristics of its components, the test environment, and the operations. Therefore, it is necessary to calibrate these devices by traceable phantom standards. However, most of the currently available phantoms are homogeneous phantoms that cannot simulate multimodal and dynamic characteristics of biological tissue. Here, we show the fabrication of heterogeneous tissue-simulating phantoms using a production line integrating a spin coating module, a polyjet module, a fused deposition modeling (FDM) module, and an automatic control framework. The structural information and the optical parameters of a &#34;digital optical phantom&#34; are defined in a prototype file, imported to the production line, and fabricated layer-by-layer with sequential switch between different printing modalities. Technical capability of such a production line is exemplified by the automatic printing of skin-simulating phantoms that comprise the epidermis, dermis, subcutaneous tissue, and an embedded tumor.

Spin coating, polyjet printing, and fused deposition modeling are integrated to produce multilayered heterogeneous phantoms that simulate structural and functional properties of biological tissue.

생물학적 조직을 시뮬레이션하기 위한 팬텀의 멀티모달 3D 프린팅

Biomedical optical imaging is playing an important role in diagnosis and treatment of various diseases. However, the accuracy and the reproducibility of ...

In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VOx

Resistive switching crossbar architecture is highly desired in the field of digital memories due to low cost and high-density benefits. Different materials show variability in resistive switching properties due to the intrinsic nature of the material used, leading to discrepancies in the field because of underlying operation mechanisms. This highlights a need for a reliable technique to understand mechanisms using nanostructural observations. This protocol explains a detailed process and methodology of in&#160;situ nanostructural analysis as a result of electrical biasing using transmission electron microscopy (TEM). It provides visual and reliable evidence of underlying nanostructural changes in real time memory operations. Also included is the methodology of fabrication and electrical characterizations for asymmetric crossbar structures incorporating amorphous vanadium oxide. The protocol explained here for vanadium oxide films can be easily extended to any other materials in a metal-dielectric-metal sandwiched structure. Resistive switching crossbars are predicted to serve the programmable logic and neuromorphic circuits for next-generation memory devices, given the understanding of the operation mechanisms. This protocol reveals the switching mechanism in a reliable, timely, and cost-effective way in any type of resistive switching materials, and thereby predicts the device&#39;s applicability.

In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VOx

Presented here is a protocol for analyzing nanostructural changes during in&#160;situ biasing with transmission electron microscopy (TEM) for a stacked metal-insulator-metal structure. It has significant applications in resistive switching crossbars for the next generation of programmable logic circuits and neuromimicking hardware, to reveal their underlying operation mechanisms and practical applicability.