Investigating the Effect of Thermoelectric Processing on Ionic Aggregation in Thermoplastic Ionomers
By: Prasant Vijayaraghavan
Ionomers are a class of polymers which contain a small fraction of charged groups in the polymer backbone. These ionic groups aggregate (termed ionic aggregates) to form temporary cross-links that break apart over the ionic dissociation temperature and re-aggregate on cooling, influencing the mechanical properties of these polymers. In addition to enhanced mechanical properties, some ionomers also exhibit self-healing behavior. The self-healing behavior is a consequence of weakly bonded ionic aggregates breaking apart and re-aggregating after puncture or a ballistic impact. The structure and properties of ionomers have been studied over the last several decades; however, there is a lack of understanding of the influence of an electrostatic field on ionic aggregate morphology. Characterizing the effect of temperature and electric field on the formation and structure of these ionic aggregates will lead to preparation of ionomers with enhanced structural properties. This work focuses on Surlyn® 8940 which is a poly-ethelene methacryclic acid co-polymer in which a fraction of the carboxylic acid is terminated by sodium. In this work, Surlyn® is thermoelectrically processed over its ionic dissociation temperature in the presence of a strong electrostatic field. Thermal, X-ray and Infrared studies are performed on the ionomer to study the effect of the thermoelectric processing. It is shown that the application of a thermoelectric field leads to increase in the ionic aggregate order in these materials and reduction in crystal size distribution.
By: Dr. Belinda Hurley
The OSU Libraries spend many millions each year to provide resources that are not freely available online. Belinda Hurley, OSU Libraries’ liaison for Physical Sciences and Engineering, will present an overview of available resources and services to those new to the OSU Libraries system.
Engineering DNA Origami Structures On Cell Surface for Detection of Cancer Biomarkers in Cellular Microenvironment
By: Melika Shahhosseini
Cancer cells exhibit specific gene mutations, such as mutations in the tumor suppressor gene BRCA1 that are observed in breast cancer. Circulating tumor DNA (ctDNA) are the mutated genes that are released by dead cancer cells into blood circulation, which presents a potential marker for early stage diagnosis. There are currently multiple methods to detect ctDNAs for early cancer diagnosis, normally by performing liquid biopsies. However, current detection methods have limitations such as demand for specialized equipment, low sensitivity and insufficient specificity. Furthermore, none of the available techniques provide in-situ detection, which may provide the additional benefit of elucidating mechanisms of cancer progression mediated by ctDNA. To address these limitations, we aim to exploit cells as sensing platforms by engineering their cell membranes to detect ctDNA in-situ with fluorescence based reporting. DNA origami is self-assembly of geometric complex nanostructures using DNA as building blocks. We recently reported a highly novel approach to engineer cell-membrane function by embedding DNA-origami nanodevices onto the cell surface via cholesterol-conjugated oligonucleotides as amphiphilic anchors . We programmed DNA origami nanodevices to detect presence of 2 different DNA sequence (targets) on the cell surface by emitting fluorescence signal in two different channels. Preliminary results show that introduction of each DNA target at 1μM, increases fluorescence signal by 50%. Also, structures are able to simultaneously detect two target DNA sequences over a broad range of concentrations (1nM to 1μM). Preliminary results also suggest we can detect binding events on individual cells, and in some cases with sub-cellular resolution. Therefore, we expect that implementing DNA origami structures on cell membranes will enable us to profile the spatiotemporal distribution of ctDNA in cellular microenvironment. For future steps, we plan to incorporate multiple cancer-related aptamers into DNA structures to enable simultaneous detection of multiple cancer biomarkers. Specifically, we are interested in detection of combinations of different cancer related genes with other cancer biomarkers (e.g. platelet-derived growth factor and pH) in cellular microenvironment. This technique can be implemented as a highly sensitive liquid biopsy method for early detection of cancer.
Electric Fields Control Motility of Metastatic Breast Cancer Cells
By: Ayush Garg
The onset of metastasis in breast cancer patients reduces their survival rates from over 90% to less than 20%. The key to stopping and treating metastatic breast lesions lies in understanding the mechanisms that regulate cancer cell migration. Mechanisms that regulate cancer cell migration in response to chemical cues, mechanical cues, physical cues etc. have been widely studied but effects of electric fields on motility are not well understood. While previous direct current electric field (dc EF) studies have shown directional galvanotactic migratory response in various cancer cells, the underlying mechanisms regulating this responses are still unclear. Here we show that by applying non-contact induced electric fields (iEFs, field strength < 100 µV/cm), we can directionally increase spontaneous migration rate of MDA-MB-231 cells. We found that this directional response was Akt dependent. Further, iEFs directionally hindered epidermal growth factor (EGF) induced migration of MDA-MB-231s by inhibiting EGFR phosphorylation, adversely impacting normal mitochondrial function, and disrupting actin polarization. Finally, we found that combined treatment of iEFs with MK2206 (an Akt inhibitor), resulted in ~21% slower migration speeds compared to untreated controls. Taken collectively, this body of results represents a significant step toward identifying how low frequency (< 1 MHz) iEFs interact with mammalian breast cancer cells and the possible governing mechanisms controlling their migratory responses. The results presented here could lay the foundation for exploring non-contact and new therapeutic approaches that may be used in a stand-alone manner or in conjunction with chemotherapy such as an Akt inhibitor based strategy.
Measurements of N2(A3Σ+u, v) Kinetics in Nonequilibrium Plasmas and Nonequilibrium Hypersonic Flows
By: Elijah Jans
Understanding the impact that real gas effects have behind strong shock waves is critical for design of hypersonic vehicles. These real gas effects cause nonequilibrium energy transfer and chemical kinetics that need to be understood for predictive modeling of flows over hypersonic vehicles. To experimental study these effects use of several optical diagonistics techniques will be presented with recent laboratory results.
Thermal transport across GaN and SiC Interface
by Vinay Chauhan
Noon – 12:30pm E525
The heat flux in GaN based high-electron mobility transistors (HEMTs) can reach up to a few kW/cm2 which can lead to failure of devices in case of poor heat dissipation. The thermal interface resistance between the GaN and the substrate material is the major obstruction in the heat flow path, mainly effected by the thermal conductivity of the substrate and the lattice mismatch. The previously developed models showed good concurrence of thermal interface resistance with experimental data at high temperatures (>300 K) but failed to follow the physics at low temperatures. The proposed experiments will enable us to find the reliable thermal properties related to the interface, and thus help in improving and developing the models.
SLS is starting back up again for the Spring Semester January 31st!
If you are interested in presenting at the Student Lecture Series this semester, please submit a title and the desired date and time to the SLS Chair Elijah Jans email@example.com. All slots will be filled on a first come first serve basis. Further details, including the format and schedule can be found in the overview and schedule tabs.
Want to improve your presenting skills? Want to show-off your research to your friends and class-mates? Sign up to give a talk at the Fall 2017 Student Lecture Series. Don’t have anything ready to present… not a problem come listen to your classmates discuss their work over pizza and learn by example.
The Student Lecture Series is a student run forum for graduate and BS/MS students from the MAE Department to present their work. The series is designed to provide opportunities for students to develop their technical presentation skills, promote the research of the department, and encourage faculty and student discussions of research. The low stress and informal atmosphere fosters a positive learning environment in which faculty and students of all levels can interact and learn from each other.
If you are interested in presenting at the Student Lecture Series this semester, please submit a title and the desired date and time to the SLS Chairs Mike Adam firstname.lastname@example.org or Elijah Jans email@example.com. All slots will be filled on a first come first serve basis. Further details, including the format and schedule can be found in the overview and schedule tabs.
Using Dynamic Simulations to Investigate Muscle Forces during the Sit to Stand Transfer and Stair Climbing
By: Elena Caruthers
Noon – 1 pm E100
Abstract: While activities of daily living such as rising from a chair or climbing stairs are performed with relative ease by healthy adults, they are considered to be some of the most challenging activities in the home, especially for the elderly and those with lower limb pathologies such as knee osteoarthritis. Current rehabilitation strategies used for these populations are not 100% effective as some patients do not have significant improvements in pain or the ability to rise from a chair or climb stairs. In order to potentially improve and inform targeted intervention programs, the role of individual muscles needs to be investigated further. I will describe the utility of experimental tools such motion capture, which has been used for movies like Avatar, and how they can be used in joint with dynamic simulations to study the behavior of individual muscles, including estimating individual muscle forces produced during a task. I will also discuss the work my collaborators and I did to investigate muscle forces generated when rising from a chair or during stair climbing in a young, healthy population and how these results can be used in the future to help inform current rehabilitation strategies for populations that experience difficulty completing those tasks.
Bio: Elena Caruthers received a B.S. degree in engineering (with a mechanical emphasis) and a B.A. in dance from Hope College in 2012. She is currently pursuing her doctoral degree at The Ohio State University in Mechanical Engineering, working for Dr. Robert Siston in the Neuromuscular Biomechanics Laboratory. While at Ohio State, she was awarded the National Science Foundation Predoctoral Fellowship in 2013 and was selected to be an instructor for mechanics of materials at Ohio State through the Future Faculty Program in the 2015-16 school year. Her research interests include lower limb muscle function during activities of daily living in healthy and pathological populations as well as engineering education.