CNR-SPIN, sezione di Napoli, Via Cintia, 80126 Napoli, Italy.
University of Cincinnati, UC Simulation Center, 2728 Vine Street, Cincinnati, OH 45219, USA.
Sci Rep. 2017 Mar 14;7:43496. doi: 10.1038/srep43496.
Many amorphous materials show spatially heterogenous dynamics, as different regions of the same system relax at different rates. Such a signature, known as Dynamic Heterogeneity, has been crucial to understand the nature of the jamming transition in simple model systems and is currently considered very promising to characterize more complex fluids of industrial and biological relevance. Unfortunately, measurements of dynamic heterogeneities typically require sophisticated experimental set-ups and are performed by few specialized groups. It is now possible to quantitatively characterize the relaxation process and the emergence of dynamic heterogeneities using a straightforward method, here validated on video microscopy data of hard-sphere colloidal glasses. We call this method Differential Variance Analysis (DVA), since it focuses on the variance of the differential frames, obtained subtracting images at different time-lags. Moreover, direct visualization of dynamic heterogeneities naturally appears in the differential frames, when the time-lag is set to the one corresponding to the maximum dynamic susceptibility. This approach opens the way to effectively characterize and tailor a wide variety of soft materials, from complex formulated products to biological tissues.
许多无定形材料表现出空间异质动力学，即同一系统的不同区域以不同的速率弛豫。这种特征，称为动态非均一性，对于理解简单模型系统中的阻塞转变的性质至关重要，并且目前被认为非常有希望用于表征更复杂的工业和生物相关流体。不幸的是，动态非均质性的测量通常需要复杂的实验设置，并且仅由少数专门小组进行。现在，可以使用一种简单的方法来定量表征弛豫过程和动态非均质性的出现，这里在硬球胶体玻璃的视频显微镜数据上进行了验证。我们将这种方法称为差分方差分析（DVA），因为它专注于差分帧的方差，通过在不同时间延迟处减去图像来获得。此外，当时间延迟设置为对应于最大动态灵敏度的时间延迟时，动态非均质性在差分帧中自然出现。这种方法为有效表征和定制各种软材料开辟了道路，从复杂配方产品到生物组织。
