Content | Navigation |

Physics

 


Seminars

Spring 2016 Seminars

DateTitleAuthor
January 18, 2016<Martin Luther King Jr. Day>
January 25, 2016Molecular dynamics for photocatalytic and gas storage applications: metal-organic super-containers and porous silicaWendi Sapp
February 1, 2016Basic theory of fluctuating lattice BoltzmannAlexander Wagner
February 8, 2016Polymers, rivets, and airframe coatings
Aaron Feickert
February 15, 2016<Presidents Day>

February 22, 2016

When experts struggle with physics, and how that can inform teachingAlistair McInerny
February 29, 2016
March 7, 2016Single-Molecule Electronic Measurements of the Dynamic Flexibility of Histone DeacetylasesJames Froberg
March 14, 2016
March 21, 2016
March 28, 2016<Holiday>
April 4, 2016Soft Colloidal Particles in Crowded EnvironmentsAlan Denton
April 11, 2016One Bend, Two Bend: Stepping Towards a Complex Folded ObjectAndrew B. Croll
April 18, 2016Federal Research Grants and the New Public Access MandatesRobert Correll

April 25, 2016

<Special MNT/Physics Seminar>Probing Single-Molecule Protein Conformational Dynamics in Enzymatic Reactions and Cell SignalingH. Peter Lu
April 26, 2016<Special MNT/Physics Seminar>Mechanics of Ultrathin Polymer Films: Viscoelasticity, Dynamics and Rubbery Response of MembranesGregory McKenna
May 2, 2016TBATim Twohig
May 9, 2016<Exam Week!>

 

 

Federal Research Grants and the New Public Access Mandates

Robert Correll

Library,
North Dakota State University,

 

Monday April 18, 3:00-4:00pm, Refreshments at 2:30.

221 South Engineering,

 

Over the past few years, federal funding agencies have begun implementing new requirements for researchers receiving grants to ensure public access to research data and publications. These requirements will have significant effects on both researchers and the broader scientific publishing ecosystem. This talk will situate the new mandates within the broader conversation about open access and scholarly communications, and discuss how researchers can comply with the new requirements in order to remain eligible for federal funding. Several common misconceptions about the mandates, public access, and copyright more generally will be addressed, and potential challenges for researchers, publishers and librarians will be discussed.

Probing Single-Molecule Protein Conformational Dynamics in Enzymatic Reactions and Cell Signaling

H. Peter Lu

Ohio Eminent Scholar and Professor,
Department of Chemistry
Bowling Green State University,

 

Tuesday April 25, 3:00-4:00pm, Refreshments at 2:30.

271 Bachellor Technology Center

 

Enzymatic reactions are traditionally studied at the ensemble level, despite significant static and dynamic inhomogeneities.  Subtle conformational changes play a crucial role in protein functions, and these protein conformations are highly dynamic rather than being static. We applied single-molecule spectroscopy to study the mechanisms and dynamics of enzymatic reactions involved with kinase and lysozyme proteins.  Enzymatic reaction turnovers and the associated structure changes of individual protein molecules were observed simultaneously in real-time by single-molecule FRET detections.  We obtained the rates for single-molecule conformational active-site open-close fluctuation and correlated enzymatic reactions.  Our new approach is applicable to a wide range of single-molecule FRET measurements for protein conformational changes under enzymatic reactions and protein-protein interactions in cell signaling.  Using this approach, we analyzed enzyme-substrate complex formation dynamics to reveal (1) multiple intermediate conformational states, (2) conformational motions involving in active complex formation and product releasing from the enzymatic active site, and (3) conformational memory effects in the chemical reaction process. Furthermore, we have applied AFM-enhanced single-molecule spectroscopy to study the mechanisms and dynamics of enzymatic reactions.  We obtained the rates for single-molecule conformational active-site open-close fluctuation and correlated enzymatic reactions.  We have demonstrated a specific statistical analysis to reveal single-molecule FRET anti-correlated fluctuations from a high background of fluorescence correlated thermal fluctuations.  Our new approach is applicable to a wide range of single-molecule AFM-FRET measurements for protein conformational changes under enzymatic reactions, including AFM-FRET control of enzymatic reactivity by mechanical-force manipulating protein conformations.

Mechanics of Ultrathin Polymer Films: Viscoelasticity, Dynamics and Rubbery Response of Membranes

Gregory B. McKenna

Department of Chemical Engineering,
Texas Tech. University,

 

Tuesday April 26, 3:00-4:00pm, Refreshments at 2:30.

271 Bachellor Technology Center

 

Determination of the mechanical response of polymeric materials with dimensions less than 100 nm is a continuing challenge.  Here we describe a novel membrane (“nano-bubble”) inflation method we have developed for the purpose of making measurements of the creep response of ultrathin polymer films and show two major findings. The first is that the material dynamics as measured by the creep response of the membranes depends dramatically on film thickness.  For example, in polystyrene films, the dynamics is accelerated so much that the glass transition temperature Tg of a 11 nm thick film is reduced by approximately 50 K relative to the macroscopic Tg [1].  Furthermore, we have discovered that the nominal rubbery plateau in ultrathin films is stiffened by upwards of two orders of magnitude relative to the macroscopic state and the rate of stiffening (stiffening index S) correlates with the shape of the segmental relaxation in accordance with a recent model proposed by Ngai, Prevosto and Grassia [2].  We have elaborated this finding further and observe a strong correlation with the fragility index m that is related to glass formation according to the Angell categorization [3] of super cooled liquids.  These results will be discussed in terms of current understanding of the impact of nanoconfinement on the glass transition behavior of polymers. In addition to being able to characterize the creep response of the ultrathin polymer films, we have also succeeded in adapting the bubble inflation method to make measurements on a graphene/polymer nano-sandwich structure and show that the method can be used to not only extract the stiffness of the graphene inner layer of the composite but that the method can be used to extract the interfacial shear strength of the polymer-graphene couple [4].

 

 

[1]  P.A. O’Connell, S.A. Hutcheson and G.B. McKenna, Journal of Polymer Science: Part B: Polymer Physics, 46, 1952-1965 (2008).

[2] K.L. Ngai, D. Prevosto and L. Grassia, Journal of Polymer Science: Part B: Polymer Physics, 51, 214-224 (2013).

[3]  C.A. Angell, Journal of Non-Crystalline Solids, 73, 1-17 (1985).

[4]  X. Li, J. Warzywoda and G.B. McKenna, 55, 4976-4982 (2014).

o either subscribe to or unsubscribe from this listserve please send an email to Listserv@listserv.nodak.edu with an empty subject and containing a body of
SUB NDSU-PHYSICS-SEMINAR or SIGNOFF NDSU-PHYSICS-SEMINAR respectively.


Student Focused. Land Grant. Research University.

Follow NDSU
  • Facebook
  • Twitter
  • RSS
  • Google Maps

Site Manager: Physics Webmaster
Published by Department of Physics

Last Updated: Monday, April 18, 2016 11:56:12 AM