Tag Archives: softmatter

Merced team studying shark electrosensing

Our lab recently published two new papers on the subject of electro-sensing in cartilaginous fishes, a group that includes sharks and rays. The sensing organ (AoL) in these fish is filled with a gel-like substance and we are interesting is figuring out how this gel works!

In the first paper our team, Lead by Molly Phillips, a graduate student in Chris Amemiya’s lab at Merced investigated the role of chitin in the electrosensory gel.

“Evidence of chitin in the ampullae of Lorenzini of chondrichthyan fishes”Molly Phillips, W. Joyce Tang, Matthew Robinson, Daniel Ocampo Daza, Khan Hassan, Valerie Leppert, Linda S. Hirst, Chris T. Amemiya, , Current Biology, Volume 30, Issue 20, 2020, Pages R1254-R1255, https://doi.org/10.1016/j.cub.2020.08.014.


The second paper focuses on the structure of the gel.

Structural Characteristics and Proton Conductivity of the Gel Within the Electrosensory Organs of Cartilaginous Fishes Molly Phillips, Alauna Wheeler, Matthew J Robinson, Valerie Leppert, Manping Jia, Marco Rolandi, Linda S Hirst, Chris T Amemiya, ISCIENCE, in press (2021) August 03, (2021)  https://doi.org/10.1016/j.isci.2021.102947

Co-authors include Physics graduate student Alauna Wheeler, who conducted the X-ray work with Phillips at the Advanced Light Source at Lawrence Berkeley National Laboratory; graduate student Matthew Robinson; and UC Santa Cruz electrical engineering Professor Marco Rolandi and his graduate student Manping Jia. The Santa Cruz team provided equipment and expertise for the conductance measurements.

Nanofoams – Nature communications

Nanoparticle-based hollow microstructures formed by two-stage nematic nucleation and phase separation


Sheida T. Riahinasab, Amir Keshavarz, Charles N. Melton, Ahmed Elbaradei, Gabrielle I. Warren, Robin L. B. Selinger, Benjamin J. Stokes & Linda S. Hirst 

Nature Communications volume 10, Article number: 894 (2019)

read the paper here

Rapid bulk assembly of nanoparticles into microstructures is challenging, but highly desirable for applications in controlled release, catalysis, and sensing. We report a method to form hollow microstructures via a two-stage nematic nucleation process, generating size-tunable closed-cell foams, spherical shells, and tubular networks composed of closely packed nanoparticles. Mesogen-modified nanoparticles are dispersed in liquid crystal above the nematic-isotropic transition temperature (TNI). On cooling through TNI, nanoparticles first segregate into shrinking isotropic domains where they locally depress the transition temperature. On further cooling, nematic domains nucleate inside the nanoparticle-rich isotropic domains, driving formation of hollow nanoparticle assemblies. Structural differentiation is controlled by nanoparticle density and cooling rate. Cahn-Hilliard simulations of phase separation in liquid crystal demonstrate qualitatively that partitioning of nanoparticles into isolated domains is strongly affected by cooling rate, supporting experimental observations that cooling rate controls aggregate size. Microscopy suggests the number and size of internal voids is controlled by second-stage nucleation.