Long Range Interactions Workshop

A short course and two seminars based on work supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award

DE-SC0008068 (DOE-BES-DMSE-BMM).

 

August 7–10, 2012

White 411

 

Tuesday, August 7­­­­­

 

10:00 a.m.

Dr. Rudi Podgornik

Department of Physics

University of Ljubljana, Slovenia

 

“Molecular Attractions: van der Waals Interactions”

Lecture 1 in this three lecture short course. There are three important sources of attractive interactions in soft matter systems. This lecture introduces general principles as well specific model systems related to van der Waals interactions, which are due to correlated electromagnetic field fluctuations in dielectrically inhomogeneous media, and their role in osmotic pressure equilibria of multilamellar lipid systems.

 

11:00 a.m.

Dr. Wai-Yim Ching

Curators' Professor of Physics

University of Missouri – Kansas City

 

“Ab Initio Simulation of Double Strand b-DNA Molecules”

Deoxyribonucleic acid or DNA is a nucleic acid molecule that is pivotal to all living organisms and biomedical science as well as nanotechnology. The properties of DNA are ultimately based on the fundamental electronic structure under interatomic interactions. However, there are still relatively few ab initio calculations of the electronic properties of DNA molecules. This talk presents some results on the electronic structure and optical properties of two models of double strand b-DNA molecules, AT10 and GC10. They were constructed using a combination of modeling tools. These models are periodic in the axial (z) direction with 10 base pairs (AT or GC) and 20 Na ions acting as counter ions to neutralize the PO4 groups in the backbone. The calculations were performed using the first-principles density functional theory based OLCAO method. The calculated optical dielectric functions show high anisotropy in the energy range above the HOMO-LUMO gap. Also to be discussed are the results of over-stretching the DNA model (AT10 model) under tensile strain. The overall goal is to apply methods in condensed matter theory to complex bimolecular systems for greater insights. The importance of interdisciplinary collaborations along this line computational research will be discussed.

 

Wednesday, August 8­­­­­

10:00 a.m.

Dr. Rudi Podgornik

 

“Molecular Attractions: Electrostatic Correlation Interactions”

Lecture 2 in this three lecture short course. This lecture introduces general principles as well specific model systems related to electrostatic correlation interactions, which are due to electrostatically strongly coupled mobile counterions between charged macromolecules, and their role in DNA collapse in multivalent salts.

 

11:00 a.m.

Dr. Adrian Parsegian

Professor, Gluckstern Chair, Physics Department

University of Massachusetts, Amherst

 

“Conformation and Transport of Polymers Used to Measure Intermolecular Forces”

The measurement of forces between lipid membranes, DNA molecules, polysaccharides, and proteins is usually made by putting them under the osmotic stress of an excluded polymer that creates the arrays observed by x-ray diffraction. This procedure requires careful measurement of polymer osmotic pressures over wide ranges of molecular weight and concentration. While building up this large data set, we realized that there was material here to re-examine the theory of polymers under crowded conditions. A simple description and theory has emerged. At low concentrations, polymers follow the van't Hoff law for pressures linear in concentration. At very high concentrations, polymers follow the less familiar des Cloiseaux law for pressure going as the 9/4ths power of concentration. The big surprise is that these two limiting laws, combined with only one fitting parameter, suffice to describe a huge set of osmotic pressure data for any given polymer species for all measured molecular weights. This osmotic pressure of crowding is the driving force for transport of large polymers through relatively small pores.

 

Thursday, August 9

10:00 a.m.

Dr. Rudi Podgornik

 

“Molecular Attractions: Polyelectrolyte Bridging Interactions”

Lecture 3 in this three lecture short course. This lecture introduces general principles as well specific model systems related to polyelectrolyte bridging interactions that are due to elastic deformation of stretched polyelectrolyte chains between charged macromolecular interfaces, and their role in organization of eucaryotic genome, specifically in the interactions between nucleosomal core particles.

 

Presented by the Solar Durability and Lifetime Extension (SDLE) Center

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