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This program is designed to allow local societies access to nationally known speakers who tour the country largely at the expense of the National Society. Each year the Local Affiliates Luncheon at The Microscopy and Microanalysis Meeting selects the speakers for the following year. The Local Affiliates Luncheon is attended by members of local societies from all over the country and any member of those societies is welcome, and indeed encouraged, to attend. The tour speaker program is Organized by Paul Hlava, The Affiliated Regional Societies Chair, of Sandia National Laboratory. Tour speaker visits to your local society meeting should be coordinated through Paul. His email address is pfhlava@sandia.gov. |
 Pictured: MAS Tour Speaker Dr. Joe Michael (left) of Sandia National Laboratories confers with Ian Anderson (right) of NIST, the current president of MAS during the Thursday evening reception at the 2006 Fall Meeting of the Appalachian Regional Microscopy Society (AReMS). Joe delivered the keynote talk, "Applications of EBSD to Materials: From Nanomaterials to Welds to Meteorites," at that evening's opening night banquet. |
Modern transmission electron microscopes offer sub-nanometer,
or in some cases, sub-angstrom probe sizes. The ultimate resolution
of structure and composition measurements, however, is often limited
by practical concerns, such as sample stability, drift and counting
statistics, rather than probe size. In order to get an accurate
understanding of the true structure and composition of nanoscale
materials, it is typically necessary to perform multiple complementary
analyses, including high- resolution imaging, Z-contrast imaging,
diffraction studies, energy dispersive x-ray spectroscopy and electron
energy loss spectroscopy. I will discuss the practical limits of
these analyses for materials ranging from fuel cell catalysts and
quantum dots, to thin film magnetic devices and cosmic dust.
Rhonda Stroud received her bachelor’s degree in physics from Cornell University in 1991 and her doctorate in physics from Washington University in St. Louis in 1996. Her thesis work on icosahedrally coordinated Ti-Zr-Ni alloys led to the discovery of the first stable Ti-based quasicrystal. As an NRC Postdoctoral Fellow at the Naval Research Laboratory (1996-1998), she examined the effects of disorder on colossal magnetoresistance in manganites. Since becoming a staff member in the Materials Science and Technology Division at NRL in 1998, her research focus has been relating atomic-scale structure to materials properties in nanophase systems ranging from fuel cell catalysts and quantum dots to presolar dust grains.
Fungi are fundamentally recyclers. Their main function in the environment is to break down complex materials, which allows the components to be re-used by other organisms. These complex materials include dead plants, dead animals, building materials, valued artifacts of civilization and any number of other things. Problems arise when these organisms invade the built environment, either work or living spaces. Various methods, such as air sampling, have been commonly used to estimate the density of fungi in a structure. Volumetric sampling may indicate high levels of fungi or one particular fungus in a building compared to the outdoor environment or some predetermined standard. This method may indicate the presence of viable fungal conidia or hyphal fragments in the air column but it cannot identify sites of colonization. Surface cultures may indicate the presence of viable fungal propagules but do not prove colonization. Surface sampling for light microscopy using clear adhesive tape mounts may demonstrate the presence of colonizing fungi. The methodology, such as types of tape and optics employed may affect the results obtained. Examination of tape samples from environmental surfaces may show the level of colonization and, in many cases, allow for identification of colonizing species. Scanning electron microscopy studies of suspect materials may determine the nature of surface features and contamination not readily identifiable in the light microscope. Suspect materials may be shown to be biological in nature or non-biological surface. Microanalysis of materials may yield clues to the origin of non-biological contamination. Rapid and accurate analysis of suspect materials on indoor surfaces is vital to the identification of potential fungal colonization sites. These data may be used as an aid to determining an appropriate course of action.
Automobile air conditioning systems might be considered an extreme environment for many microorganisms. Organisms surviving and proliferating in these systems may be presented with temperature changes ranging from sub-zero to over 140oF, water activity from saturation to dryness and a nutrient complexity including varying levels of hydrocarbons. Microbial communities may develop in these systems and sometimes proliferate to the extent of massive colonization and production of objectionable odors. In a few instances microorganisms emanating from ACS have been associated with hypersensitivity pneumonitis and other allergic reactions. We have demonstrated that foam insulation and glues, in particular, on system insulations may be colonized by fungi such as Aspergillus, Aureobasidium, Cladosporium, and Penicillium. Such fungi often are implicated in colonization of similar substrates in buildings categorized with the sick building syndrome. Combined light microscopy, scanning and transmission electron microscopy and culture techniques have provided profiles of the microbial communities which inhabit some automobile air conditioning systems.
Robert Simmons is a native of Atlanta, Georgia. He earned his Bachelor of Science (Hons) degree in biological sciences at the University of Ulster, and continued with MS and Ph.D. degrees at Georgia State University. He joined the Biology Department at Georgia State University in 1983 and is the Program Director for Biological Imaging. His main research involves the interaction of microorganisms with the human environment, with an emphasis on fungi and air handling systems. Robert is the president-elect of the Southeastern Microscopy Society and councilor (biological sciences) for MSA.
The performance of scanning electron microscopes (SEMs) and focused ion beams (FIBs) has long been limited by the quality of the source of the charged particles. A new type of gas field ion source has allowed us to make an easily focused beam of helium ions. The helium ions can be used to image samples with higher resolution and better contrast mechanisms than SEMs or FIBs. The extension of this technology to heavier gases will permit operation like a traditional FIB but without gallium contamination. This talk will provide an overview of this new technology and several applications.
John Notte received his Bachelor's degree in Physics from Case Western Reserve University in 1987. As a part of his undergraduate research, he developed a precision torsion balance for measuring very small forces. John received his Ph.D. in experimental electron plasma physics from U.C. Berkeley in 1993 where he developed a trap for holding low energy electrons for arbitrarily long times. At Bates College, John taught undergraduate physics while constructing another electron trap. Since leaving academia, John has worked for AMRAY, KLA-Tencor, FEI, and now is employed at Carl Zeiss where he is developing further improvements to the helium ion source.
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