Skip to main content
Highlights

Highlights

Dynamics of disclination loops in 3D active nematic. Topological loops can nucleate spontaneously from a uniformly aligned nematic through the bend instability. Loops can split from the existing percolating network. Equivalently, topological loops can also self-annihilate and merge with other existing loops. Colors highlight the loops of interest
Dynamics of disclination loops in 3D active nematic. Topological loops can nucleate spontaneously from a uniformly aligned nematic through the bend instability. Loops can split from the existing percolating network. Equivalently, topological loops can also self-annihilate and merge with other existing loops. Colors highlight the loops of interest
Jan 24, 2020
Brandeis University

Disclination loops in 3D Active Nematics

G. Duclos4, D. Beller2, R. Adkins1, M. Varghese4 , M.  Peterson4, Arv. Baskaran4, R. Pelcovitz3, T. Powers3, S. Streichan1, Ap. Baskaran4, M.F. Hagan4, Z. Dogic1 1UCSB, 2UC Merced, 3Brown University, 4Brandeis University
Current active matter systems, such as self propelled colloids or migrating cells, are inherently 2D, which limits the potential engineering applications. Brandeis developed the first 3D active nematic material by mixing an isotropic active fluid (Microtubules + kinesin motors) with a passive nematic colloidal liquid crystal (fd viruses). Using multiview light sheet microscopy, they explored the structure and the dynamics of topological defects in a 3D active nematic.
Structure and rheology of active gels: (left) A confocal reconstruction of an active gels composed of continuously rearranging extensile microtubule bundles that is driven by continuous input of energy through the motion of molecular motors. (right) Effective viscosity of a microtubule based active gels for three different ATP concentrations which controls the speed at which kinesin motors slide microtubules apart. The dashed lines represent a molecular model that explains the peak in the sample viscosity without any adjustable parameters.
Structure and rheology of active gels: (left) A confocal reconstruction of an active gels composed of continuously rearranging extensile microtubule bundles that is driven by continuous input of energy through the motion of molecular motors. (right) Effective viscosity of a microtubule based active gels for three different ATP concentrations which controls the speed at which kinesin motors slide microtubules apart. The dashed lines represent a molecular model that explains the peak in the sample viscosity without any adjustable parameters.
Jan 24, 2020
Brandeis University

Rheology of active isotropic gels

D. Gagnon, C. Dessii, D. Blair (Georgetown University), J. Berezney (Brandeis University), R. Boros, Z. Dogic (UCSB)
Cytoplasmic flows, bacterial colonies, and algal blooms are ubiquitous examples of active suspensions assembled from self-propelled particles, which internally inject energy into their suspending medium and, at sufficient concentrations, can produce large-scale flows. Linking macroscale material properties of active suspension to their underlying microscopic dynamics is a key challenge to describing these materials.
Colloidal rafts with switchable attractive and repulsive interaction. (top) Schematic and (bottom) optical microscopy images of colloidal rafts that assemble in membranes that have no net chirality. Differential interference microscopy (left) and fluorescence images (right) of colloidal rafts that assemble into crystalline lattices with unusual square symmetry. Such assemblages can be understood by measuring the effective membrane-mediated raft-raft interactions that can switch between repulsions and attractions and which are regulated by the raft chirality.
Colloidal rafts with switchable attractive and repulsive interaction. (top) Schematic and (bottom) optical microscopy images of colloidal rafts that assemble in membranes that have no net chirality. Differential interference microscopy (left) and fluorescence images (right) of colloidal rafts that assemble into crystalline lattices with unusual square symmetry. Such assemblages can be understood by measuring the effective membrane-mediated raft-raft interactions that can switch between repulsions and attractions and which are regulated by the raft chirality.
Jan 23, 2020
Brandeis University

Repulsive and attractive colloidal rafts with switchable comformational states

J. Miller, C. Joshi, A. Baskaran, A Baskaran, M. Hagan (Brandeis University), G. Grason (U. Mass Amherst), and Z. Dogic (UCSB) 
We describe hierarchical assemblages of colloidal rods that mimic some of the complexity and reconfigurability of biological structures. In particular, we show that chiral rod-like inclusions dissolved in an achiral colloidal membrane assemble into rafts, which are adaptable finite-sized liquid droplets that exhibit two distinct chiral states of opposite handedness. Interconverting between these two states switches the membrane-mediated raft interactions between long-ranged repulsions and attractions.
PZT-gated SNNO/LSMO composite channels exhibit significantly enhanced field effect switching due to interfacial charge transfer between SNNO and LSMO.
PZT-gated SNNO/LSMO composite channels exhibit significantly enhanced field effect switching due to interfacial charge transfer between SNNO and LSMO.
Jun 17, 2019
University of Nebraska - Lincoln

Interfacial Charge Engineering in Ferroelectric-Gated Mott Transistors

X. Chen, X. Zhang, M. A. Koten, Z. Xiao, L. Zhang, Jeffrey E. Shield, Peter A. Dowben and Xia Hong (University of Nebraska - Lincoln)
Nebraska MRSEC researchers have fabricated complex oxide heterostructures with atomic precision, exploiting them to build a prototype nonvolatile Mott transistor.
Building Enduring Pathways in STEM: Incorporating Traditional Ways of Knowing in Materials Research
Building Enduring Pathways in STEM: Incorporating Traditional Ways of Knowing in Materials Research
Jun 12, 2019
Harvard University

Building Enduring Pathways in STEM: Incorporating Traditional Ways of Knowing in Materials Research

This unique partnership between Navajo Technical University and the Harvard MRSEC will build enduring pathways for undergraduate Native American students into STEM by including traditional tribal perspectives and methods of scientific inquiry in materials science research and education.
Acoustophoretic Printing: Printing Soft Materials with Sound
Acoustophoretic Printing: Printing Soft Materials with Sound
Jun 12, 2019
Harvard University

Acoustophoretic Printing: Printing Soft Materials with Sound

To enhance drop formation, a team at the Harvard MRSEC led by Lewis created a new printing method that relies on generating sound waves to assist gravity, dubbing this new technique acoustophoretic printing.
Microreactors for Abiotic Ligation of nanoRNA
Microreactors for Abiotic Ligation of nanoRNA
Jun 10, 2019
University of Colorado at Boulder

Microreactors for Abiotic Ligation of nanoRNA

The scientific understanding of evolution is extensive, but limited by some notable, if not embarrassing, gaps.  Among the great challenges of basic science is to understand the origin of life, and, in particular, the origin of the double helix structure of stacked base pairs of DNA and RNA, life’s most remarkable molecular creation.
Hydrogels from DNA mimicking polymers and DNA
Hydrogels from DNA mimicking polymers and DNA
Jun 10, 2019
University of Colorado at Boulder

Hydrogels from DNA mimicking polymers and DNA

X. Han1, D.W. Domaille1, B.D. Fairbanks1, L. He1, H.R. Colver1, X. Zhang1, J.N. Cha1, C.N. Bowman1   1 Department of Chemical and Biological  Engineering, University of Colorado, Boulder, CO 80309, USA.
Radical, light initiated chemical reactions were used to synthesize multifunctional, star-shaped polmyers with each chain end bound to a DNA mimicking polymer (the “Click Nucleic Acid or CNA developed with the support of the NSF).  
The Role of Chain Connectivity Across an Interface on the Dynamics of a Nanostructured Block Copolymer
The Role of Chain Connectivity Across an Interface on the Dynamics of a Nanostructured Block Copolymer
Jun 6, 2019
Princeton University

The Role of Chain Connectivity Across an Interface on the Dynamics of a Nanostructured Block Copolymer

D. Christie1, R.A. Register1, R.D. Priestley1, “The Role of Chain Connectivity Across an Interface on the Dynamics of a Nanostructured Block Copolymer,” Physical Review Letters, 121, 247801 (2018). 1Princeton University
Princeton investigators developed an approach to directly measure the influence of chain connectivity on the glass transition temperature of copolymers for the first time. This development is important as it provides insights into the design of copolymer interfaces for applications in which transport of entities is important.
Schematic of expected conducting lanes where electrons can flow at the boundaries between regions with opposite orientations of electron orbits.
Schematic of expected conducting lanes where electrons can flow at the boundaries between regions with opposite orientations of electron orbits.
Jun 6, 2019
Princeton University

Controllable electron flow in quantum wires

M. T. Randeria1, K. Agarwal1, B. E. Feldman2, H. Ding1, H. Ji1, R. J. Cava1, S. L. Sondhi1, S. A. Parameswaran3 and A. Yazdani1 1 Princeton Univesity,  2 Stanford University 3 University of Oxford
Princeton investigators detected channels of conducting electrons that form between two quantum states on the surface of a bismuth crystal subjected to a high magnetic field. These two states consist of electrons moving in elliptical orbits with different orientations. The researchers found that the current flow in these channels can be turned on and off, making these channels a new type of controllable quantum wire.

Showing 311 to 320 of 1397