Materials Seminar - Fall 2018

Randy Fishman 

 The Dynamical Fingerprints of Multiferroic Materials

Randy Fishman, PhD
Distinguished R&D Research Scientist,
Oak Ridge National Lab, Oak Ridge, Tennessee
September 14, 2018
1:00 - 2:00 p.m.
Science Hall W1002

Inelastic neutron-scattering and optical measurements provide the dynamical “fingerprint” for the multiferroic state of a material with coupled electrical and magnetic properties. These experimental techniques have been used to identify the spiral and cycloidal spin states in two very different multiferroic materials: 3.5\% Ga-doped CuFeO2 and pure BiFeO3. By comparing the observed and calculated spectrum of spin excitations, we conclude that the magnetic ground state of doped CuFeO2 is a distorted spiral with a distribution of turn angles. Spectroscopic measurements of BiFeO3 in a magnetic field reveal that the magnetic state is a cycloid that tilts from one hexagonal layer to the next. For both materials, comparison between theory and experiment is used to evaluate the microscopic interactions responsible for the magnetic state and its multiferroic behavior.

Christine Langton

Cementitious Material Manufacture, Applications and Challenges

Christine A. Langton, PhD
Sr. Advisory Scientist,
Savannah River National Laboratory, Aiken, SC
September 28, 2018
4:00 - 5:00 p.m.
Science Hall W1002

Cementitious materials are the most commonly used construction materials in the world. Plasters, mortars and concretes are the oldest engineered, multi component, building materials. Cement chemistries, manufacturing methods, and mix designs have evolved and matured over more than a thousand years. However, the magnitude and diversity of the applications, desire for increased performance and environmental issues associated with these materials demand continuous technology development. An overview of inorganic cements and cementitious materials will be provided along with global challenges associated with these materials. Examples of applications and technology needs associated with energy production will be discussed. In addition, new cementitious materials designed and implemented by the Savannah River National Laboratory for the US Department of Energy (DOE) legacy waste management program will be described.

James Burgess

Biological Structures on Solid electrodes for Diagnostics Sensing

James Burgess
The Graduate School
Augusta University
Adjunct Professor of Chemistry
Case Western Reserve University
November 16, 2018
1:00 - 2:00 p.m.
Science Hall W1002

Methods for microelectrode detection of cholesterol diffusion at the surface of cell(s) have been developed for single cell studies, mouse tissues, and the human mucosa (inner cheek). As summarized in our recent review article, cholesterol is a tightly regulated major structural component of the cell plasma membrane (PM) where if forms stoichiometric complexes with phospholipids and sphingolipids. The term “active cholesterol” refers to PM cholesterol not complexed to lipids, a cholesterol state that arises above a threshold mole fraction of cholesterol in the PM. Active cholesterol level in the PM provides a control mechanism for cellular cholesterol homeostasis through its recognition by membrane bound proteins that activate genes of cholesterol synthesis enzymes. Uptake of LDL (bad cholesterol), production and release of HDL (good cholesterol) as well as reversible storage of cholesterol by covalent modification are also regulated and dependent on PM cholesterol (thermodynamic) activity: active cholesterol. The amount of active cholesterol in the PM also exhibits a regulatory role in basal activity of several biomolecular processes by direct binding to proteins and by indirect local environmental effects within the PM. For these reasons, active cholesterol is a key general biomarker for cellular dysfunction and we have demonstrated that it has specific relevance to the cystic fibrosis disease state in cell and animal models. Continuing collaboration with Tom Kelley in the Departments of Pediatrics and Pharmacology at Case Western Reserve University, we aim to extend these trends to cystic fibrosis in humans to provide diagnostic and management monitoring as well as to increase our basic understanding of disease pathology at the cellular level. The general electrochemical platform is also proposed for bloodless glucose analysis at the mucosa as a means of preventing transmission of pathogens in healthcare settings. Batch-produced sensor chips are being developed using state of the art micro/nano-manufacturing techniques through collaboration with Minchul Shin in the Department of Mechanical Engineering at Georgia Southern University.