Pratiti Mandal

Stretchable, High-k Dielectric Elastomers through Liquid-Metal Inclusions

An all-soft-matter composite with exceptional electro-elasto properties is demonstrated by embedding liquid-metal inclusions in an elastomer matrix. This material exhibits a unique combination of high dielectric constant, low stiffness, and large strain limit (ca. 600% strain). The elasticity, electrostatics, and electromechanical coupling of the composite are investigated, and strong agreement with predictions from effective medium theory is found.

Image segmentation of nanoscale Zernike phase contrast X-ray computed tomography images

Zernike phase contrast is a useful technique for nanoscale X-ray computed tomography (CT) imaging of materials with a low X-ray absorption coefficient. It enhances the image contrast by phase shifting X-ray waves to create changes in amplitude. However, it creates artifacts that hinder the use of traditional image segmentation techniques. We propose an image restoration method that models the X-ray phase contrast optics and the three-dimensional image reconstruction method. We generate artifact-free images through an optimization problem that inverts this model. Though similar approaches have been used for Zernike phase contrast in visible light microscopy, this optimization employs an effective edge detection method tailored to handle Zernike phase contrast artifacts. We characterize this optics-based restoration method by removing the artifacts in and thresholding multiple Zernike phase contrast X-ray CT images to produce segmented results that are consistent with the physical specimens. We quantitatively evaluate and compare our method to other segmentation techniques to demonstrate its high accuracy.

Multifunctional Hydrogels with Reversible 3D Ordered Macroporous Structures

Three‐dimensionally ordered macroporous (3DOM) hydrogels prepared by colloidal crystals templating display highly reversible shape memory properties, as confirmed by indirect electron microscopy imaging of their inverse replicas and direct nanoscale resolution X‐ray microscopy imaging of the hydrated hydrogels. Modifications of functional groups in the 3DOM hydrogels result in various materials with programmed properties for a wide range of applications.

Liquid Metals: Stretchable, High-k Dielectric Elastomers through Liquid-Metal Inclusions (Adv. Mater. 19/2016).

An all-soft-matter composite consisting of liquid metal microdroplets embedded in a soft elastomer matrix is presented by C. Majidi and co-workers on page 3726. This composite exhibits a high dielectric constant while maintaining exceptional elasticity and compliance. The image shows the composites microstructure captured by 3D X-ray imaging using a nano-computed tomographic scanner.

Image Restoration of Phase Contrast Nano Scale X-ray CT Images

Zernike phase contrast is a technique useful for nano-scale X-ray imaging of materials with a low absorption coefficient. It enhances the image contrast using a phase ring. However, it also creates artifacts that hinder the use of traditional techniques for X-ray computed tomography (CT) image segmentation. We propose an image restoration method that models the phase contrast optics and minimizes an energy function. Though similar techniques have been used for visible light microscopy, this method deals with more spacious samples using an effective edge detection method. This paper demonstrates the removal of artifacts in multiple slices of phase contrast X-ray CT images and the potential in using this technique to aid CT image segmentation.