Date Title Author
Aug. 30, 2021    
Sept. 6, 2021 <Holiday> Labor Day  
Sept. 13, 2021    
Sept. 20, 2021    
Sept. 27, 2021    
Oct. 1, 2021 <Special Day>BIOPHYSICAL CHARACTERIZATION OF LIVING CELLS AND MEMBRANE RECEPTORS BY ATOMIC FORCE SPECTROSCOPY Lina Alhahlooly
Oct. 4, 2021    
Oct. 11, 2021    
Oct. 18, 2021    
Oct. 25, 2021    
Oct. 28, 2021 <Special Day>Fundamental studies of interfacial forces acting on thin films  
  Timothy Twohig  
Nov. 1, 2021    
Nov. 8, 2021    
Nov. 15, 2021    
Nov. 22, 2021    
Nov. 29, 2021    
Dec. 6, 2021 <Dead Week>  
Dec. 13, 2021 <Exam Week  

Fundamental studies of interfacial forces acting on thin films

Timothy Twohig

Ph.D. Candidate,
Department of Physics,
North Dakota State University

Thursday, October 28, 9:00-10:00am, Via Zoom.  Contact Andrew Croll for zoom link.

Please note the special time and date!

The seminar is part of Timothy's PhD thesis defense.

The ancient art of origami uses sheets of paper and precise folding to create complex, three-dimensional shapes out of flat, quasi two-dimensional sheets.  Lately, origami has emerged as a unique way to solve many problems in engineering and science, and as technology and devices are scaled to smaller sizes many attempts have been made to scale origami methods down too.  In pursuit of a more detailed understanding of origami on microscales, studies were conducted on many aspects of thin film assembly involved in the creation of complex and stable structures at a microscopic size.  First inspired by ‘capillary origami methods’, the microscopic details of the interaction of a capillary drop with a thin film were explored in relation to macroscopic observations.  Next, the effect of the adhesion of a film to its substrate was explored.  This interaction enabled the creation and guiding of peel fronts which resulted in precisely controlled placement of folds even in purely elastic materials. Research to explore the stability of ‘elastic not plastic’ folds and their application in origami design was conducted, giving guidelines for which films could be used in specific applications.  Finally, new structures were designed and built from thin films using adhesion rather than plastic folding in origami inspired design.  The new method allowed traditional origami designs to be created, but more importantly, it enabled new structures that cannot be created with traditional origami methods.  We finish by showing how this new ‘adhesion origami’ is already present in many everyday situations.

Biophysical Characterization of Living Cells and Membrane Receptors by Atomic Force Spectroscopy

Lina Alhalhooly

Ph.D. Candidate,
Department of Physics,
North Dakota State University

Friday, October 1, 1:00-2:00pm, Via Zoom.  Contact Alexander Wagner for zoom link.

Please note the special time and date!

The seminar is part of Lina's PhD thesis defense.

Cellular biomechanics such as membrane deformability play an important role in controlling the cell development and maintaining cellular functions. By exploiting atomic force spectroscopy technique, we have studied dynamic cellular biomechanics in response to the environmental changes and interactions between membrane receptors and their ligands. First, the biomechanical and biophysical properties of various cancer cells were monitored after chemotherapeutic drug exposure in low and high oxygen condition. The cellular elasticity and morphological changes were measured in a time-dependent manner before and after treatment. Our results show direct evidence of the drug-induced changes of the cytoskeletal components, as well as the effect of a low-oxygen environment on enhancing the cancer cell resistance against the chemotherapeutic treatment. Second, single and multiple interactions between membrane receptors (integrins) and peptide ligands (RGD) were examined. The unbinding force of the single receptor-ligand bond and force-based receptor distributions on the cell surface were quantified and compared between several cells. By varying loading rates, the dissociation off rates of the ligand-receptor bond and the changes in Gibbs free energy between a ligand-receptor bound and transition state in the presence and absence of the external force were examined. Furthermore, multivalent RGD-integrin interactions along with the thermodynamic parameters and a free energy landscape alteration during synchronous and asynchronous unbinding processes of multiple RGD-integrins bonds were also examined.

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