Category Archives: featured

Fundamentals of Soft matter science 2nd Ed – out now!

October 15, 2019 Linda Hirst

Summary

This revised edition continues to provide the most approachable introduction to the structure, characteristics, and everyday applications of soft matter. It begins with a substantially revised overview of the underlying physics and chemistry common to soft materials. Subsequent chapters comprehensively address the different classes of soft materials, from liquid crystals to surfactants, polymers, colloids, and biomaterials, with vivid, full-color illustrations throughout. There are new worked examples throughout, new problems, some deeper mathematical treatment, and new sections on key topics such as diffusion, active matter, liquid crystal defects, surfactant phases and more.

• Introduces the science of soft materials, experimental methods used in their study, and wide-ranging applications in everyday life.

• Provides brand new worked examples throughout, in addition to expanded chapter problem sets and an updated glossary.

• Includes expanded mathematical content and substantially revised introductory chapters.　

This book will provide a comprehensive introductory resource to both undergraduate and graduate students discovering soft materials for the first time and is aimed at students with an introductory college background in physics, chemistry or materials science.　

featured, liquid crystals, Soft Matter

Hirst wins Hilsum Medal

May 17, 2019 Linda Hirst

Linda Hirst has been named this year’s recipient of the British Liquid Crystal Society’s C. Hilsum Medal for her contributions to liquid crystal science and technology.

Read the UC Merced new article here

Linda and her PhD advisor Prof Helen Gleeson from Leeds University at the awards ceremony

active matter, Biomaterials, Biopolymers, featured, Soft Matter

Congratulations Dr Joe Lopes

November 22, 2016 Linda Hirst Leave a comment

Congratulations go to Dr Lopes – newest graduate from the Hirst Lab.

Joe works on kinesin – based microtubule transport and active matter. He will be starting a postdoc in March at Brandeis University with Prof Guilliaume Duclos.

https://sites.google.com/site/ducloslab/

Biomaterials, featured, graduate studies, Lipids, Soft Matter

Congratulations Dr Lor!

November 9, 2015 Linda Hirst

Dr Chai Lor successfully defended his PhD thesis in the BEST (Bioengineering and small scale technologies) program on October 26th. Chai was a bioengineering undergraduate at UC Merced and a member of the first graduating class.

“Phase Behavior and Nanotube Formation in Lipid Membranes”

Biological cells are protected by a complex barrier called the lipid membrane. The lipid membrane is a soft material structure consisting of many lipid molecules held together by hydrophobic forces in an aqueous solution. Two simple experimental models were employed to investigate the role of specific lipid molecules in biological membranes. The first model investigated the phase behavior of the binary lipid mixture, 1-dipalmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphoethanolamine (DHA-PE) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), using small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS). Our results shows that DHA-PE induces phase separation into a DHA rich liquid crystalline (L_α) phase and a DHA poor gel (L_β’) phase at overall DHA-PE concentrations as low as 0.1mol%. In addition, we find that the structure of the L_β’ phase, from which the DHA-PE molecules are largely excluded, is modified in the phase-separated state at low DHA-PE concentrations, with a decrease in bilayer thickness of 1.34nm for 0.1mol% at room temperature compared to pure DPPC bilayers. The second model investigated the formation of lipid nanotubes using an anchor system consisting of lipids, kinesin molecular motors, and microtubules in a flow cell. Lipid tubulation was conducted on two different membranes, 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and DPPC. Lipid nanotubes were pulled from anchored giant unilamellar vesicles (GUVs) by drag force generated from the flow inside the channel. The results showed that DPPC membranes cannot generate lipid nanotubes while DOPC can, which was expected. We find that a drag force of approximately ≈7.9 pN is sufficient for tubule extraction and that it only requires 1-2 kinesin motor proteins for anchoring the GUV.

“Low concentrations of docosahexanoic acid significantly modify membrane structure and phase behavior”
C. Lor and L.S. Hirst, MEMBRANES, 5(4), 857-874 Link (2015)

featured, liquid crystals, Soft Matter

Kyle Kabasaras, CAMP summer student, presents research at UC Merced Symposium

August 14, 2015 Linda Hirst Leave a comment

This summer Kyle Kabasaras presented his original research project at the UC Merced undergrad research symposium.

Investigating quantum dot assembly in a cholesteric liquid crystal

An ongoing goal in condensed matter physics is directly controlling the self-assembly of quantum dots (QDs) into specific structures while maintaining their original electronic and optical properties. One method of controlling the self-assembly of QDs is to disperse them within a liquid crystal (LC) medium and apply a variety of thermal stimulations. Recently, our lab developed a method of creating spherical, vesicle-shaped QDs within a nematic LC. Vesicle formation depends on the QD concentration in the LC as well as the LC’s intermolecular dispersion forces and thermal properties. In this project, we investigate the dispersion of CdSe/ZnS (core/shell) QDs in a cholesteric LC (CLC) medium and predict the QD aggregations to cluster near the LC defects. By varying parameters such as QD concentration and temperature, we exploit the CLC’s sensitive optical and thermal properties. To observe these effects, we apply spectrophotometry, polarized optical microscopy, and fluorescence microscopy. These techniques highlight the aggregation of QDs within the host CLC and identify how LC phase transitions determine where QDaggregates form. This work illustrates the possibility of new LC-based QD devices, and we will continue by exploring the lasing potential of our sample.

The Hirst Lab