Name: calibration procedures for orthogonal superposition rheology
Uploaded: 2020-11-18T13:00:00.000+00:00
Duration: 8 min 43 s
Description: Watch this Scientific Journal Video about Calibration Procedures for Orthogonal Superposition Rheology at JoVE.com

란 타오 (Ran Tao)는 미국 상무부 국립 표준 기술 연구소 (National Institute of Standards and Technology)의 보조금 70NANB15H112에 감사드립니다. Aaron M. Forster에 대한 자금은 의회 세출을 통해 국립 표준 기술 연구소에 제공되었습니다.

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S., Kim, S., Vermant, J., Petekidis, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Convective+Cage+Release+in+Model+Colloidal+Glasses.">Convective Cage Release in Model Colloidal Glasses.</a> Physical Review Letters. 115 (21), 218301 (2015).</li><li>Jacob, A. R., Poulos, A. S., Semenov, A. N., Vermant, J., Petekidis, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flow+dynamics+of+concentrated+starlike+micelles:+A+superposition+rheometry+investigation+into+relaxation+mechanisms.">Flow dynamics of concentrated starlike micelles: A superposition rheometry investigation into relaxation mechanisms.</a> Journal of Rheology. 63 (4), 641-653 (2019).</li><li>Moghimi, E., Vermant, J., Petekidis, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Orthogonal+superposition+rheometry+of+model+colloidal+glasses+with+short-ranged+attractions.">Orthogonal superposition rheometry of model colloidal glasses with short-ranged attractions.</a> Journal of Rheology. 63 (4), 533-546 (2019).</li><li>Tao, R., Forster, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=End+effect+correction+for+orthogonal+small+strain+oscillatory+shear+in+a+rotational+shear+rheometer.">End effect correction for orthogonal small strain oscillatory shear in a rotational shear rheometer.</a> Rheologica Acta. 59 (2), 95-108 (2020).</li><li>Schrag, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deviation+of+velocity+gradient+profiles+from+the+"gap+loading"+and+"surface+loading"+limits+in+dynamic+simple+shear+experiments.">Deviation of velocity gradient profiles from the "gap loading" and "surface loading" limits in dynamic simple shear experiments.</a> Transactions of the Society of Rheology. 21 (3), 399-413 (1977).</li><li>Ewoldt, R. H., Johnston, M. T., Caretta, L. M., Spagnolie, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Complex Fluids in Biological Systems. Biological and Medical Physics, Biomedical Engineering. , 207-241 (2015).</li></ol>

이 백서에 사용 된 절차에 대한 전체 설명은 특정 상용 제품 및 해당 공급 업체를 식별해야합니다. 이러한 정보를 포함한다고 해서 해당 제품 또는 공급업체가 NIST에서 보증하거나 NIST에서 권장하거나 설명된 목적에 가장 적합한 재료, 도구, 소프트웨어 또는 공급업체임을 나타내는 것으로 해석되어서는 안 됩니다.

이 프로토콜에서는 이중벽 동심 실린더 형상을 사용하는 상업용 직교 중첩 유변학 기술을 위해 뉴턴 유체를 사용하여 점도 교정 측정을 수행하기 위한 자세한 실험 절차를 제시합니다. 교정 계수, 즉 1차 말단 효과 계수 CL 및 직교 종단 효과 계수 CLo는 꾸준한 전단 속도 스윕 및 직교 주파수 스윕 테스트를 수행하여 독립적으로 결정됩니다. 최종 계수를 ?...

복잡한 유체의 유변학적 특성을 이해하는 것은 신뢰할 수 있고 재현 가능한 제품의 개발 및 제조를 위한 많은 산업에 필수적입니다1. 이러한 "복합 유체"에는 퍼스널 케어 제품, 식품, 화장품 및 가정 용품과 같이 일상 생활에 널리 존재하는 현탁액, 고분자 액체 및 거품이 포함됩니다. 유변학적 또는 유동 특성(예: 점도)은 최종 용도 및 가공성에 대한 성능 지표를 설정하는 데 중요한 관심사이지만 유동 특성은 복잡한 유체 내에 존재하는 미세 구조와 상호 연결됩니다. 단순한 액체와 구별되는 복합 유체의 두드러진 특징 중 하나는 여러 길이 척도에 걸쳐 다양한 미세 구조를 가지고 있다는 것입니다2. 이러한 미세 구조는 다양한 유동 조건에 의해 쉽게 영향을 받을 수 있으며, 이는 차례로 거시적 특성의 변화를 초래합니다. 흐름과 변형에 반응하는 복잡한 유체의 비선형 점탄성 거동을 통해 이 구조-속성 루프를 잠금 해제하는 것은 실험적 유변학자에게 여전히 어려운 과제입니다.
직교 중첩(OSP) 유변학3 은 이러한 측정 문제를 해결하기 위한 강력한 기술입니다. 이 기술에서는 작은 진폭의 진동 전단 흐름이 단방향 1차 정상 전단 흐름에 직각으로 중첩되어 부과된 1차 전단 흐름 하에서 점탄성 완화 스펙트럼을 동시에 측정할 수 있습니다. 보다 구체적으로, 작은 진동 전단 섭동은 선형 점탄성4의 이론을 사용하여 분석 할 수있는 반면, 비선형 유동 조건은 1 차 정상 전단 흐름에 의해 달성됩니다. 2개의 유동장이 직교하고 따라서 결합되지 않기 때문에, 섭동 스펙트럼은 1차 비선형 유동(5) 하에서의 미세구조의 변화와 직접적으로 관련될 수 있다. 이 고급 측정 기술은 복잡한 유체의 구조-특성-처리 관계를 설명하여 제형, 처리 및 적용을 최적화할 수 있는 기회를 제공합니다.
현대 OSP 유변학의 구현은 갑작스러운 깨달음의 결과가 아닙니다. 오히려 수십 년간의 맞춤형 장치 개발을 기반으로합니다. 최초의 맞춤형 OSP 장치는 Simmons6에 의해 1966 년으로 거슬러 올라가며그 후 7,8,9,10에 많은 노력이 이루어졌습니다. 이러한 초기 맞춤형 장치는 정렬 문제, 펌핑 흐름 효과(직교 진동을 제공하기 위한 밥의 축 방향 이동으로 인해) 및 기기 감도 제한과 같은 많은 단점을 겪습니다. 1997년 Vermant et al.3은 상업용 별도의 모터 변환기 레오미터에서 힘 재균형 변환기(FRT)를 수정하여 이전 장치보다 점도 범위가 넓은 유체에 대한 OSP 측정을 가능하게 했습니다. 이 수정을 통해 수직력 재균형 변환기가 응력 제어 레오미터로 작동하여 축방향 힘 측정 외에도 축 방향 진동을 부과할 수 있습니다. 최근에는 Vermant의 방법론에 따라 OSP 측정에 필요한 형상이 상용 별도의 모터 변환기 레오미터용으로 출시되었습니다.
상용 OSP 유변학의 출현 이후, 다양한 복합 유체의 조사에 이 기술을 적용하는 것에 대한 관심이 증가하고 있습니다. 예로는 콜로이드 현탁액11,12, 콜로이드 겔 13,14 및 유리15,16,17이 있습니다. 상용 기기의 가용성은 OSP 연구를 촉진하지만 복잡한 OSP 지오메트리는 다른 일상적인 유변학 기술보다 측정에 대한 더 깊은 이해가 필요합니다. OSP 플로우 셀은 이중벽 동심 실린더(또는 쿠엣) 형상을 기반으로 합니다. 개방형 상단 및 개방형 하단 설계로 유체가 환형 틈새와 저장소 사이를 앞뒤로 흐를 수 있습니다. 제조업체가 형상 설계를 최적화했음에도 불구하고 OSP 작동을 수행할 때 유체는 불균일한 유동장, 기하학적 최종 효과 및 잔류 펌핑 흐름을 경험하며, 이 모든 것이 상당한 실험 오류를 유발할 수 있습니다. 우리의 이전 연구18은이 기술을 위해 뉴턴 유체를 사용하는 중요한 최종 효과 보정 절차를보고했습니다. 정확한 점도 결과를 얻으려면 1차 및 직교 방향 모두에서 적절한 최종 효과 계수를 적용해야 합니다. 이 프로토콜에서는 OSP 유변학 기술에 대한 자세한 교정 방법론을 제시하고 측정 오류를 줄이기 위한 모범 사례에 대한 권장 사항을 제공하는 것을 목표로 합니다. OSP 지오메트리 설정, 샘플 로딩 및 OSP 테스트 설정에 대해 이 백서에 설명된 절차는 비뉴턴 유체 측정을 위해 쉽게 채택하고 번역할 수 있어야 합니다. 사용자는 여기에 설명된 교정 절차를 활용하여 모든 유체 분류(뉴턴 또는 비뉴턴)에 대한 OSP 측정 전에 응용 분야에 대한 최종 효과 보정 계수를 결정하는 것이 좋습니다. 최종 요인에 대한 교정 절차는 이전에 보고되지 않았습니다. 본 백서에 제공된 프로토콜은 일반적으로 정확한 유변학적 측정을 수행하는 방법에 대한 단계별 가이드 및 팁과 레오미터 사용자가 간과할 수 있는 "원시" 데이터와 "측정된" 데이터의 이해에 대한 기술 리소스도 설명합니다.

<table><tbody><tr><td>Advanced Peltier System</td><td>TA Instruments</td><td>402500.901</td><td>Enviromental control device</td></tr><tr><td>ARES-G2 Rheometer</td><td>TA Instruments</td><td>401000.501</td><td>Rheometer</td></tr><tr><td>Brookfield Silicone Fluid, 12500cP</td><td>AMTEK Brookfield</td><td>12500 cps</td><td>Viscosity standard liquid</td></tr><tr><td>OSP Slotted Bob, 33 mm</td><td>TA Instruments</td><td>402796.902</td><td>Bob, upper geometry</td></tr><tr><td>OSP Slotted Double Gap Cup, 34 mm</td><td>TA Instruments</td><td>402782.901</td><td>Double wall cup, lower geometry</td></tr><tr><td>Pipette (1 &amp;ndash; 10 mL)</td><td>Eppendorf</td><td>3120000089</td><td>To load test materials</td></tr><tr><td>Pipette (100 &amp;ndash; 1,000 &amp;micro;L)</td><td>Eppendorf</td><td>3123000063</td><td>To load test materials</td></tr><tr><td>Pipette Tips (0.5 &amp;ndash; 10 mL)</td><td>Eppendorf</td><td>022492098</td><td>To load test materials</td></tr><tr><td>Pipette Tips (50 &amp;ndash; 1,000 &amp;micro;L)</td><td>Eppendorf</td><td>022491555</td><td>To load test materials</td></tr><tr><td>Spatula</td><td>VWR</td><td>82027-532</td><td>To load test materials</td></tr><tr><td>TRIOS</td><td>TA Instruments</td><td>v4.3.1.39215</td><td>Rheometer software</td></tr></tbody></table>

calibration procedures for orthogonal superposition rheology

직교 중첩(OSP) 유변학은 1차 전단 흐름에 직교하는 작은 진폭의 진동 전단 변형을 중첩하는 고급 유변학 기술입니다. 이 기술을 사용하면 비선형 흐름 조건에서 복잡한 유체의 구조 역학을 측정 할 수 있으며, 이는 광범위한 복잡한 유체의 성능을 이해하고 예측하는 데 중요합니다. OSP 유변학 기법은 1960년대부터 오랜 개발 역사를 가지고 있으며, 주로 이 기법의 힘을 강조한 맞춤형 장치를 통해 개발되었습니다. OSP 기술은 현재 유변학 커뮤니티에서 상업적으로 이용 가능합니다. OSP 지오메트리의 복잡한 설계와 비이상적인 유동장을 감안할 때 사용자는 측정 오류의 크기와 원인을 이해해야 합니다. 이 연구는 측정 오류를 줄이기 위한 모범 사례에 대한 권장 사항을 포함하는 뉴턴 유체를 사용한 교정 절차를 제시합니다. 구체적으로, 최종 효과 계수 결정 방법, 샘플 충전 절차 및 적절한 측정 범위(예: 전단 속도, 주파수 등)의 식별에 대한 자세한 정보가 제공됩니다.

12.2Pas 실리콘 점도 표준에 대한 점도 교정 측정의 대표적인 결과는 그림 5 및 그림 6에 나와 있습니다. 기본 최종 효과 계수와 직교 최종 효과 계수는 모두 보정 실행에 대해 1.00으로 설정됩니다. 그림 5는 이중 y축 플롯에서 전단 속도의 함수로 안정적인 전단 점도와 토크를 보여줍니다. 실리콘 액체는 뉴턴 유체입니다. 예상대로, ?...

Watch this Scientific Journal Video about Calibration Procedures for Orthogonal Superposition Rheology at JoVE.com

Calibration Procedures for Orthogonal Superposition Rheology

우리는 최종 효과 보정 계수 결정 방법 및 실험 오류를 줄이기 위한 모범 사례에 대한 권장 사항을 포함하여 뉴턴 유체를 사용하는 상용 직교 중첩 유변학 기술에 대한 자세한 교정 프로토콜을 제시합니다.

직교 중첩 유변학을 위한 교정 절차

Orthogonal superposition (OSP) rheology is an advanced rheological technique that involves superimposing a small-amplitude oscillatory shear deformation ...

calibration-procedures-for-orthogonal-superposition-rheology

Universidad San Sebastian

Research

JoVE Journal

Engineering

2.0K 조회수.  National Institute of Standards and Technology. 우리는 최종 효과 보정 계수 결정 방법 및 실험 오류를 줄이기 위한 모범 사례에 대한 권장 사항을 포함하여 뉴턴 유체를 사용하는 상용 직교 중첩 유변학 기술에 대한 자세한 교정 프로토콜을 제시합니다.

비디오: Calibration Procedures for Orthogonal Superposition Rheology

Measurement of the Rheology of Crude Oil in Equilibrium with CO2 at Reservoir Conditions

A rheometer system to measure the rheology of crude oil in equilibrium with carbon dioxide (CO2) at high temperatures and pressures is described. The system comprises a high-pressure rheometer which is connected to a circulation loop. The rheometer has a rotational flow-through measurement cell with two alternative geometries: coaxial cylinder and double gap. The circulation loop contains a mixer, to bring the crude oil sample into equilibrium with CO2, and a gear pump that transports the mixture from the mixer to the rheometer and recycles it back to the mixer. The CO2 and crude oil are brought to equilibrium by stirring and circulation and the rheology of the saturated mixture is measured by the rheometer. The system is used to measure the rheological properties of Zuata crude oil (and its toluene dilution) in equilibrium with CO2 at elevated pressures up to 220 bar and a temperature of 50 &#176;C. The results show that CO2 addition changes the oil rheology significantly, initially reducing the viscosity as the CO2 pressure is increased and then increasing the viscosity above a threshold pressure. The non-Newtonian response of the crude is also seen to change with the addition of CO2.

Measurement of the Rheology of Crude Oil in Equilibrium with CO2 at Reservoir Conditions

A method for measuring the rheology of crude oil in equilibrium with carbon dioxide at reservoir conditions is presented.

CO와 평형 상태에있는 원유의 레올로 지의 측정<sub&gt; 2</sub&gt; 저수지 조건

A rheometer system to measure the rheology of crude oil in equilibrium with carbon dioxide (CO2) at high temperatures and pressures is described. The ...

연구

환경과학

Dielectric RheoSANS &#8212; Simultaneous Interrogation of Impedance, Rheology and Small Angle Neutron Scattering of Complex Fluids

A procedure for the operation of a new dielectric RheoSANS instrument capable of simultaneous interrogation of the electrical, mechanical and microstructural properties of complex fluids is presented. The instrument consists of a Couette geometry contained within a modified forced convection oven mounted on a commercial rheometer. This instrument is available for use on the small angle neutron scattering (SANS) beamlines at the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR). The Couette geometry is machined to be transparent to neutrons and provides for measurement of the electrical properties and microstructural properties of a sample confined between titanium cylinders while the sample undergoes arbitrary deformation. Synchronization of these measurements is enabled through the use of a customizable program that monitors and controls the execution of predetermined experimental protocols. Described here is a protocol to perform a flow sweep experiment where the shear rate is logarithmically stepped from a maximum value to a minimum value holding at each step for a specified period of time while frequency dependent dielectric measurements are made. Representative results are shown from a sample consisting of a gel composed of carbon black aggregates dispersed in propylene carbonate. As the gel undergoes steady shear, the carbon black network is mechanically deformed, which causes an initial decrease in conductivity associated with the breaking of bonds comprising the carbon black network. However, at higher shear rates, the conductivity recovers associated with the onset of shear thickening. Overall, these results demonstrate the utility of the simultaneous measurement of the rheo-electro-microstructural properties of these suspensions using the dielectric RheoSANS geometry.

Here, we present a procedure for the measurement of simultaneous impedance, rheology and neutron scattering from soft matter materials under shear flow.

유전체 RheoSANS - 임피던스, 레올 로지 및 복잡한 유체의 작은 각도 중성자 산란의 동시 심문

A procedure for the operation of a new dielectric RheoSANS instrument capable of simultaneous interrogation of the electrical, mechanical and ...

공학

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 ...

Longitudinal Measurement of Extracellular Matrix Rigidity in 3D Tumor Models Using Particle-tracking Microrheology

The mechanical microenvironment has been shown to act as a crucial regulator of tumor growth behavior and signaling, which is itself remodeled and modified as part of a set of complex, two-way mechanosensitive interactions. While the development of biologically-relevant 3D tumor models have facilitated mechanistic studies on the impact of matrix rheology on tumor growth, the inverse problem of mapping changes in the mechanical environment induced by tumors remains challenging. Here, we describe the implementation of particle-tracking microrheology (PTM) in conjunction with 3D models of pancreatic cancer as part of a robust and viable approach for longitudinally monitoring physical changes in the tumor microenvironment, in situ. The methodology described here integrates a system of preparing in vitro 3D models embedded in a model extracellular matrix (ECM) scaffold of Type I collagen with fluorescently labeled probes uniformly distributed for position- and time-dependent microrheology measurements throughout the specimen. In vitro tumors are plated and probed in parallel conditions using multiwell imaging plates. Drawing on established methods, videos of tracer probe movements are transformed via the Generalized Stokes Einstein Relation (GSER) to report the complex frequency-dependent viscoelastic shear modulus, G*(&#969;). Because this approach is imaging-based, mechanical characterization is also mapped onto large transmitted-light spatial fields to simultaneously report qualitative changes in 3D tumor size and phenotype. Representative results showing contrasting mechanical response in sub-regions associated with localized invasion-induced matrix degradation as well as system calibration, validation data are presented. Undesirable outcomes from common experimental errors and troubleshooting of these issues are also presented. The 96-well 3D culture plating format implemented in this protocol is conducive to correlation of microrheology measurements with therapeutic screening assays or molecular imaging to gain new insights into impact of treatments or biochemical stimuli on the mechanical microenvironment.

Particle-tracking microrheology can be used to non-destructively quantify and spatially map changes in extracellular matrix mechanical properties in 3D tumor models.

입자 추적 microrheology은을 사용하여 3D 종양 모델에서 세포 외 매트릭스 강성의 경도 측정

The mechanical microenvironment has been shown to act as a crucial regulator of tumor growth behavior and signaling, which is itself remodeled and ...

생체공학

Combining Microfluidics and Microrheology to Determine Rheological Properties of Soft Matter during Repeated Phase Transitions

The microstructure of soft matter directly impacts macroscopic rheological properties and can be changed by factors including colloidal rearrangement during previous phase changes and applied shear. To determine the extent of these changes, we have developed a microfluidic device that enables repeated phase transitions induced by exchange of the surrounding fluid and microrheological characterization while limiting shear on the sample. This technique is &#181;2rheology, the combination of microfluidics and microrheology. The microfluidic device is a two-layer design with symmetric inlet streams entering a sample chamber that traps the gel sample in place during fluid exchange. Suction can be applied far away from the sample chamber to pull fluids into the sample chamber. Material rheological properties are characterized using multiple particle tracking microrheology (MPT). In MPT, fluorescent probe particles are embedded into the material and the Brownian motion of the probes is recorded using video microscopy. The movement of the particles is tracked and the mean-squared displacement (MSD) is calculated. The MSD is related to macroscopic rheological properties, using the Generalized Stokes-Einstein Relation. The phase of the material is identified by comparison to the critical relaxation exponent, determined using time-cure superposition. Measurements of a fibrous colloidal gel illustrate the utility of the technique. This gel has a delicate structure that can be irreversibly changed when shear is applied. &#181;2rheology data shows that the material repeatedly equilibrates to the same rheological properties after each phase transition, indicating that phase transitions do not play a role in microstructural changes. To determine the role of shear, samples can be sheared prior to injection into our microfluidic device. &#181;2rheology is a widely applicable technique for the characterization of soft matter enabling the determination of rheological properties of delicate microstructures in a single sample during phase transitions in response to repeated changes in the surrounding environmental conditions.

We demonstrate the fabrication and use of a microfluidic device that enables multiple particle tracking microrheology measurements to study the rheological effects of repeated phase transitions on soft matter.

The microstructure of soft matter directly impacts macroscopic rheological properties and can be changed by factors including colloidal rearrangement ...

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 ...

Macro-Rheology Characterization of Gill Raker Mucus in the Silver Carp, Hypophthalmichthys molitrix

The silver carp, Hypophthalmichthys molitrix, is an invasive planktivorous filter feeder fish that infested the natural waterways of the upper Mississippi River basin due to its highly efficient filter feeding mechanism. The characteristic organs called gill rakers (GRs), found in many such filter feeders, facilitate the efficient filtration of food particles such as phytoplankton that are of a few microns in size.
The motivation to investigate the rheology of the GR mucus stems from our desire to understand its role in aiding the filter feeding process in the silver carp. The mucus-rich fluid, in a &#8216;thick and sticky&#8217; state may facilitate the adhesion of food particulates. The permeation and transport through the GR membrane are&#160;facilitated by the action of external shear forces that induce varying shear strain rates. Therefore, mucus rheology can provide a vital clue to the tremendous outcompeting nature of the silver carp within the pool of filter feeding fish. Based on this it was posited that GR mucus may provide an adhesive function to food particles and act as a transport vehicle to assist in the filter feeding process.
The main objective of the protocol is to determine the yield stress of the mucus, attributed to the minimum shear stress required to initiate flow at which irreversible plastic deformation is first observed across a structured viscoelastic material. Accordingly, rheological properties of the GR mucus, i.e., viscosity, storage, and loss moduli, were investigated for its non-Newtonian, shear-thinning nature using a rotational rheometer. &#160;
A protocol presented here is employed to analyze the rheological properties of mucus extracted from the gill rakers of a silver carp, fished at Hart Creek location of the Missouri River. The protocol aims to develop an effective strategy for rheological testing and material characterization of mucus assumed to be a structured viscoelastic material.

Macro-Rheology Characterization of Gill Raker Mucus in the Silver Carp, Hypophthalmichthys molitrix

This protocol presents a method to perform rheology characterization of mucus that resides on gill rakers (GRs) of the silver carp. Viscoelastic characteristics of GR-mucus, obtained by measuring viscosity, storage and loss moduli, are evaluated for the apparent yield stress to understand the filter feeding mechanism in GRs.

실버 잉어, 하이포팔미치티스 몰리트리스의 길 레이크머 점액의 매크로-리로지 특성화

The silver carp, Hypophthalmichthys molitrix, is an invasive planktivorous filter feeder fish that infested the natural waterways of the upper Mississippi ...

Microtensiometer for Confocal Microscopy Visualization of Dynamic Interfaces

Adsorption of surface-active molecules to fluid-fluid interfaces is ubiquitous in nature. Characterizing these interfaces requires measuring surfactant adsorption rates, evaluating equilibrium surface tensions as a function of bulk surfactant concentration, and relating how surface tension changes with changes in the interfacial area following equilibration. Simultaneous visualization of the interface using fluorescence imaging with a high-speed confocal microscope allows the direct evaluation of structure-function relationships. In the capillary pressure microtensiometer (CPM), a hemispherical air bubble is pinned at the end of the capillary in a 1 mL volume liquid reservoir. The capillary pressure across the bubble interface is controlled via a commercial microfluidic flow controller that allows for model-based pressure, bubble curvature, or bubble area control based on the Laplace equation. Compared to previous techniques such as the Langmuir trough and pendant drop, the measurement and control precision and response time are greatly enhanced; capillary pressure variations can be applied and controlled in milliseconds. The dynamic response of the bubble interface is visualized via a second optical lens as the bubble expands and contracts. The bubble contour is fit to a circular profile to determine the bubble curvature radius, R, as well as any deviations from circularity that would invalidate the results. The Laplace equation is used to determine the dynamic surface tension of the interface. Following equilibration, small pressure oscillations can be imposed by the computer-controlled microfluidic pump to oscillate the bubble radius (frequencies of 0.001-100 cycles/min) to determine the dilatational modulus The overall dimensions of the system are sufficiently small that the microtensiometer fits under the lens of a high-speed confocal microscope allowing fluorescently tagged chemical species to be quantitatively tracked with submicron lateral resolution.

This manuscript describes the design and operation of a microtensiometer/confocal microscope to do simultaneous measurements of interfacial tension and surface dilatational rheology while visualizing the interfacial morphology. This provides the real-time construction of structure-property relationships of interfaces important in technology and physiology.

Adsorption of surface-active molecules to fluid-fluid interfaces is ubiquitous in nature. Characterizing these interfaces requires measuring surfactant ...

Characterizing Multiscale Mechanical Properties of Brain Tissue Using Atomic Force Microscopy, Impact Indentation, and Rheometry

To design and engineer materials inspired by the properties of the brain, whether for mechanical simulants or for tissue regeneration studies, the brain tissue itself must be well characterized at various length and time scales. Like many biological tissues, brain tissue exhibits a complex, hierarchical structure. However, in contrast to most other tissues, brain is of very low mechanical stiffness, with Young&#39;s elastic moduli E on the order of 100s of Pa. This low stiffness can present challenges to experimental characterization of key mechanical properties. Here, we demonstrate several mechanical characterization techniques that have been adapted to measure the elastic and viscoelastic properties of hydrated, compliant biological materials such as brain tissue, at different length scales and loading rates. At the microscale, we conduct creep-compliance and force relaxation experiments using atomic force microscope-enabled indentation. At the mesoscale, we perform impact indentation experiments using a pendulum-based instrumented indenter. At the macroscale, we conduct parallel plate rheometry to quantify the frequency dependent shear elastic moduli. We also discuss the challenges and limitations associated with each method. Together these techniques enable an in-depth mechanical characterization of brain tissue that can be used to better understand the structure of brain and to engineer bio-inspired materials.

We present a set of techniques to characterize the viscoelastic mechanical properties of brain at the micro-, meso-, and macro-scales.

원자 힘 현미경, 충격 들여 쓰기 및 유변학를 사용하여 뇌 조직의 멀티 스케일 기계 속성을 특성화

To design and engineer materials inspired by the properties of the brain, whether for mechanical simulants or for tissue regeneration studies, the brain ...

신경과학

Rapid Viscoelastic Characterization of Airway Mucus Using a Benchtop Rheometer

In muco-obstructive lung diseases (e.g., asthma, chronic obstructive pulmonary disease, cystic fibrosis) and other respiratory conditions (e.g., viral/bacterial infections), mucus biophysical properties are altered by goblet cell hypersecretion, airway dehydration, oxidative stress, and the presence of extracellular DNA. Previous studies showed that sputum viscoelasticity correlated with pulmonary function and that treatments affecting sputum rheology (e.g., mucolytics) can result in remarkable clinical benefits. In general, rheological measurements of non-Newtonian fluids employ elaborate, time-consuming approaches (e.g., parallel/cone-plate rheometers and/or microbead particle tracking) that require extensive training to perform the assay and interpret the data. This study tested the reliability, reproducibility, and sensitivity of Rheomuco, a user-friendly benchtop device that is designed to perform rapid measurements using dynamic oscillation with a shear-strain sweep to provide linear viscoelastic moduli (G&#39;, G&#34;, G*, and tan &#948;) and gel point characteristics (&#947;c&#160;and &#963;c) for clinical samples within 5 min. Device performance was validated using different concentrations of a mucus simulant, 8 MDa polyethylene oxide (PEO), and against traditional bulk rheology measurements. A clinical isolate harvested from an intubated patient with status asthmaticus (SA) was then assessed in triplicate measurements and the coefficient of variation between measurements is &#60;10%. Ex vivo use of a potent mucus reducing agent, TCEP, on SA mucus resulted in a five-fold decrease in elastic modulus and a change toward a more &#34;liquid-like&#34; behavior overall (e.g., higher tan &#948;). Together, these results demonstrate that the tested benchtop rheometer can make reliable measures of mucus viscoelasticity in clinical and research settings. In summary, the described protocol could be used to explore the effects of mucoactive drugs (e.g., rhDNase, N-acetyl cysteine) onsite to adapt treatment on a case-by-case basis, or in preclinical studies of novel compounds.

The viscoelastic properties of mucus play a critical role in mucociliary clearance. However, traditional mucus rheological techniques require complex and time-consuming approaches. This study provides a detailed protocol for the use of a benchtop rheometer that can rapidly and reliably perform viscoelastic measurements.

직교 중첩 유변학을 위한 교정 절차

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CO와 평형 상태에있는 원유의 레올로 지의 측정