Digital Commons Network^™

Vascular Remodeling In Hypertension, Gary L. Baumbach, Shams Ghoneim

Scanning Microscopy

Cerebral arterioles in stroke-prone spontaneously hypertensive rats (SHRSP) paradoxically become more distensible, despite hypertrophy of the vessel wall. Cerebral arterioles in SHRSP also undergo remodeling with a reduction in external diameter. Based on these findings, we have proposed the concept that remodeling of cerebral arterioles may be an important mechanism, in addition to hypertrophy, for encroachment on the vascular lumen in SHRSP. The purpose of this review is threefold. First, consequences of vascular hypertrophy that have been proposed previously are reviewed with an emphasis on the hypothesis that encroachment on the vascular lumen by hypertrophy is an important mechanism …

Environmental Scanning Electron Microscope: Some Critical Issues, G. D. Danilatos

Scanning Microscopy

In the environmental scanning electron microscope (ESEM), the gas flow around the main pressure limiting aperture establishes a density gradient through which the electron beam passes. Electron beam losses occur in this transition region and in the uniform gas layer above the specimen surface. In the oligo-scattering regime, the electron distribution consists of a widely scattered fraction of electrons surrounding an intact focussed probe. Secondary electrons are multiplied by means of gaseous ionization and detected both by the ionization current and the accompanying gaseous scintillation. The distribution of secondary electrons is governed by the applied external electric and magnetic fields …

The Function Of Seed Mucilage In Flax (Linum Usitatissimum), Karla Gengler

Honors Theses, 1963-2015

Flax seeds, when imbibed, secrete a halo of mucilage composed of polysaccharides. It has been proposed that this mucilage serves as a reservoir of nutrient for the germinating seed. Seed mucilages in other species have been found to alleviate water stress, inhibit germination in unfavorable conditions, and trap and digest microorganisms. While establishing a protocol for studying flax seed mucilage, I tested the different models and quantified the amount of mucilage per seed. I found that 11-14% of the seed's dry weight is mucilage. Nutrition and digestion of microorganisms do not appear to play roles in the function of flax …

Color Morphs Of The Crayfish Orconectes Virilis, Troy Keller

Faculty Bibliography

Adult Orconectes virilis exhibit a variety of colors from yellow to blue to dark brown that are strongly correlated with habitat background color. We used field and laboratory experiments to examine both the proximate mechanisms and the possible functions of this color variation among populations of crayfish in northern Michigan. Field transfer experiments showed that adults can change color, brown morphs becoming blue and vice versa. Light penetration measurements at six field sites indicated relationships between differential wavelength penetration and the colors exhibited by crayfish in a habitat. Holding crayfish in water from different habitats induced color changes while feeding …

Surface Chemical Reactions At The Atomic Scale: Gas Reactions With Semiconductors Studied With Scanning Tunneling Microscopy, R. S. Becker, Y. J. Chabal, G. S. Higashi, A. J. Becker

Scanning Microscopy

The vacuum tunneling microscope has been extensively utilized in the study of the surface atomic configuration of conducting materials. Analysis of features in both the tunneling images and in the tunnel junction I-V characteristic yields insight into a wide variety of processes occurring at surfaces. In the last few years, elementary chemical reactions occurring at surfaces have been examined in this manner, principally adsorption of simple gas species such as H₂, O₂, and NH₃ on semiconductors and metals. Adsorption sites have been deduced from changes brought about in surface configuration subsequent to gas exposure. The …

Recent Developments In Multichannel Raman Microprobing, J. Barbillat, M. Delhaye, E. Da Silva

Scanning Microscopy

This paper reviews the capabilities of multichannel Raman microprobing instruments with emphasis on some major innovative progress recently proposed which looks promising for the development of new fields of application. This new progress includes: confocal Raman microanalysis that provides better spatial resolution and background rejection, confocal Raman mapping that revitalizes the field of Raman imaging pioneered by us 20 years ago, the coupling of molecular Raman microanalysis to elemental electron microprobe, and finally, Raman spectroscopy with near-infrared excitation which permits avoiding the fluorescence limitation of visible Raman spectroscopy.

A Comparison Of Staining Techniques For Somatic Chromosomes Of Strawberry, Henry R. Owen, A. Raymond Miller

Faculty Research & Creative Activity

A factorial combination of pretreatments, fixatives, and stains was examined to identify the best available method for staining the chromosomes of strawberry (Fragaria × ananassa Duch. ‘Chandler’) root-tip cells. Three pretreatments ( a -bromonaphthalene, p -dichlorobenzene, and 8-hydroxyquinoline), three fixatives (Farmer’s fluid, Carnoy’s fluid, and Newcomer’s fluid), and five stains (acetocarmine, alcoholic hydrochloric-acid carmine, altered carbol fuchsin, lacto-propionic orcein, and leucobasic fuchsin) were tested. Pretreatment with either a -bromonaphthalene (saturated aqueous) or 8-hydroxyquinoline (2 mM) for 5 hours at 14C, overnight fixation in Farmer’s fluid, hydrolysis in 1 N HCl (15 minutes at 60C), and staining with altered carbol fuchsin …

Morphological Asymmetry In Mammals: Genetics And Homeostasis Reconsidered, James M. Novak, Olin E. Rhodes Jr., Michael H. Smith, Ronald K. Chesser

Faculty Research & Creative Activity

It has been hypothesized that developmental stability is increased at higher levels of genetic variability (heterozygosity) in animals. However, the existence of this relationship is questionable for homeotherms in general and mammals in particular. The difference between the sides of a bilateral character in an individual is a measure of fluctuating asymmetry that can be used as a measure of the developmental stability of mammals. Increased developmental stability should result in a greater degree of similarity between the right and left side of the body even though environmental variability would tend to increase the differences between right and left sides …

Fabrication And Characterization Of Thin, Self‐Supporting Germanium Single Crystals, M. W. Grant, P. F. Lyman, J. H. Hoogenraad, Barbara S. Carlsward, D. A. Arms, L. E. Seiberling, F. Namavar

Faculty Research & Creative Activity

Thin Gesingle crystals (≤1 μm) up to 4 mm in diameter have been fabricated from epitaxialGefilmsgrown by atmospheric pressurechemical vapor deposition on Si(100) wafers. The thin Ge windows are formed by chemically etching away both the Si substrate and the region of the Gefilm near the interface that contains misfit dislocations associated with heteroepitaxialgrowth and relaxation of the Gefilms. The resulting Gefilms are comparable in crystalline quality to bulk Ge wafers, as indicated by ion channeling studies.

Anisotropic Secondary Electron Emission From Si(100) Surface Observed By Ultrahigh Vacuum Scanning Electron Microscopy, Yoshikazu Homma

Scanning Microscopy

The effect of surface atomic structure on secondary electron (SE) emission from a Si(100)2 X 1 surface is studied using an ultrahigh vacuum scanning electron microscope with an SE detector having angular resolvability. The double domain structure, alternate 2 X 1 and 1 X 2 domains, can be clearly imaged by SEs, indicating that the SE emission varies with the orientation of dimer rows on Si(100) surface: higher intensity in the direction parallel to the dimer rows and lower intensity in the perpendicular direction. The present results demonstrate that the SE emission is greatly influenced by the atomic configuration in …

Transmission Electron Microscopy And Nanoprobe Analysis Of Ferroelectric Thin Films, Maria Huffman, Mowafak M. Al-Jassim, Chuck Echer

Scanning Microscopy

Thin-film ceramic materials have a variety of electronic applications. Several deposition techniques are currently being used to produce such films with specific properties. For example, rf-sputtered ferroelectric perovskite films, with total thicknesses less than 0.5 μ.m, are being integrated with semiconductor devices as elements for non-volatile memories. Since there is a definite need to characterize these thin films after deposition, electron microscopy has been utilized as one of the most powerful techniques available for examining their morphology and microstructure. Transmission electron microscopy (TEM) examination of these oxides proved difficult. New TEM sample preparation techniques had to be developed in order …

Amblyrhiza And The Vertebrate Paleontology Of Anguillean Caves, Donald A. Mcfarlane, Ross D. E. Macphee

WM Keck Science Faculty Papers

Recorded interest in the caves of Anguilla dates back to the second half of the nineteenth century. The earliest explorations were concerned with the locating phosphatic cave earths, and resulted in the mining of several sites. Incidental to this work, the bones of the largest island rodent ever discovered were collected from Aguillan caves. Whereas the phosphate mining operations were short-lived, the remains of the giant rodent Amblyrhiza have catalyzed a continued interest in the caves of Anguilla. The most recent series of explorations have provided the first adequate documentation of Amhlyrhiza fossil sites, and have started to yield radiometric …

X-Ray Topography, A. Zarka

Scanning Microscopy

The purpose of this paper is to discuss some elements of dynamical theory and to introduce some basic ideas on defect image formation in X-ray topographs. After some explanations of the basic principles of dynamical theory of X-rays, examples of defect contrast are given. Two examples of studies of quartz single crystals by X-ray topography are developed. First, the analysis of the X-ray spherical wave topographs of various Y-cut plates of synthetic quartz crystals show that the coherence of the lattice between the seed and the grown crystal is directly related to the density of the dislocations present in the …

Computation Of Scanning Tunneling Microscope Images Of Nanometer-Sized Objects Physisorbed On Metal Surfaces, J. P. Vigneron, I. Derycke, Th. Laloyaux, Ph. Lambin, A. A. Lucas

Scanning Microscopy

This communication deals with the application of a transfer-matrix strategy for the quantitative evaluation of the tunnel current in a scanning tunneling microscope (STM). The image given by a simple atomic-size object deposited on a metal surface is specifically examined in both modes of STM operation namely the constant-height and the constant-current modes. The two-dimensional corrugation induced at low temperature by Xe atoms physisorbed on an otherwise clean, unreconstructed Ni (110) surface is studied in detail. It is shown that the simple consideration of the elastic scattering of electrons by the three-dimensional potential barrier between the tip and the metal …

Monte Carlo Simulation Of X-Ray Spectra From Rh- And Cu-Targets Generated By Kv-Electrons, K. Araki, Y. Kimura, R. Shimizu

Scanning Microscopy

Monte Carlo simulation is applied to calculate X-ray generation in thick targets under kV electron bombardment. As a preliminary examination, we adopted the simple model based on the uses of: (1) screened Rutherford scattering formula and Bethe's stopping power for describing elastic scattering and energy loss process of penetrating electrons, respectively, (2) Burhop's ionization-cross-section and Sommerfeld's Bremsstrahlung equation for generation of characteristic and continuous X-rays, respectively. In the Monte Carlo simulation, however, more practical expressions were used for convenience of calculation to describe generation of X-rays.

To see how precisely this Monte Carlo simulation describes X-ray spectrum generated in a …

Spectral Decomposition Of Wavelength Dispersive X-Ray Spectra: Implications For Quantitative Analysis In The Electron Probe Microanalyzer, G. Remond, J. L. Campbell, R. H. Packwood, M. Fialin

Scanning Microscopy

The line shapes of Kα, Lα,β and Mα X-ray peaks of pure elements were analyzed by means of commercial wavelength dispersive spectrometers (WDS) attached to an electron probe micro-analyzer (EPMA). A pseudo-Voigt function, i.e., a linear combination of Gaussian and Lorentzian distributions, was used as a fitting profile for the X-ray peaks, with Gaussian offsets incorporated in the short wavelength (high energy) side to describe the observed asymmetry.

The asymmetry of X-ray peaks resulting from both instrumental distortions and satellite bands may lead to discrepancies in quantitative analysis with the EPMA as a function of the procedure used for deriving …

Endocytosis In Plant Protoplasts: Visualization And Quantitation Of Fluid-Phase Endocytosis Using Silver-Enhanced Bovine Serum Albumin-Gold [Abstract], Marco A. Villanueva, Josephine Taylor, Lawrence R. Griffing

Faculty Publications

No abstract provided.

Evolution Of Mammalian Social Structure, Ronald K. Chesser, Derrick W. Sugg, O. Eugene Rhodes Jr., James M. Novak, Michael H. Smith

Faculty Research & Creative Activity

Social groups may be viewed as collections of individuals exhibiting nonindependent behavior and organized in a cooperative manner. The evolutionary advantage of social behavior to individuals must be measured in its relativity to other potential behaviors, the scale of competitive interactions, and under a variety of environmental and genetic constraints. A primary tenet of social evolution is that coancestry will promote the genes of related individuals. High values of coancestry, however, do not necessarily translate into evolutionary advantage unless the primary competitive interactions occur among the groups. Coancestry is affected by the breeding tactics within and rates of genetic exchange …

Fabrication And Characterization Of Thin, Self‐Supporting Germanium Single Crystals, M. Grant, P. Lyman, J. Hoogenraad, Barbara Carlsward, D. Arms, L. Seiberling, F. Namavar

Faculty Research & Creative Activity

Thin Gesingle crystals (≤1 μm) up to 4 mm in diameter have been fabricated from epitaxialGefilmsgrown by atmospheric pressurechemical vapor deposition on Si(100) wafers. The thin Ge windows are formed by chemically etching away both the Si substrate and the region of the Gefilm near the interface that contains misfit dislocations associated with heteroepitaxialgrowth and relaxation of the Gefilms. The resulting Gefilms are comparable in crystalline quality to bulk Ge wafers, as indicated by ion channeling studies.

Electron Probe X-Ray Microanalysis Applied To Thin Surface Films And Stratified Specimens, J. L. Pouchou, F. Pichoir

Scanning Microscopy

The basic principles of X-ray microanalysis of thin surface films and stratified targets are summarized. The influence of the electron beam accelerating voltage on the analyzed depth is discussed. It is shown that in the field of soft X-rays, the effective depth of analysis is most often limited by the absorption of the radiation in the specimen itself. For high energy radiations, the importance of the secondary emission due to fluorescence excited by the continuous radiation and by the characteristic lines is outlined. The main concepts of the recent ø(ρz) models used for quantitation in the recent software packages are …

Bioremediation: A New Technology Using Inhabitants Of The Soil, Matthew Fields

Mahurin Honors College Capstone Experience/Thesis Projects

Bioremediation is the use of microorganisms to clean the environment contaminated with various pollutants such as chemical wastes and petroleum -based products. The microbes use the pollutants as their carbon source and by doing so the contaminants are broken down. This paper examined the numbers of indigenous microorganisms in soil contaminated with diesel fuel and oil. Contaminant-degrading microbes were isolated and enumerated using phenanthrene in mineral media. The breakdown of phenanthrene was used as an indicator for contaminant degradation. The effects of aeration and the addition of nutrients on bioremediation processes was also studied. Soil samples used in the performed …

Cytokine Structural Taxonomy And Mechanisms Of Receptor Engagement, Stephen R. Sprang, J. Fernando Bazan

Biological Sciences Faculty Publications

Seven discrete families of cytokines have been identified by sequence and structural analysis. Within this diverse set of protein folds, the hematopoietic growth factors and tumor necrosis factor-like cytokines display a remarkable degree of variation upon their respective topological frameworks. In addition, prototype X-ray structures of ligand-receptor complexes reveal two different strategies of receptor engagement.

Effects Of Silvicultural Treatments On Forest Birds In The Rocky Mountains: Implications And Management Recommendations, Richard L. Hutto, Sallie J. Hejl, Charles R. Preston, Deborah M. Finch

Biological Sciences Faculty Publications

The short-term effects of timber harvesting practices on landbird species vary widely among species. Thus, the maintenance of populations of all species will require a long-term management strategy that involves maintenance of a variety of habitats over a broad landscape.

Coumermycin A1 Inhibits Growth And Induces Relaxation Of Supercoiled Plasmids In Borrelia Burgdorferi, The Lyme Disease Agent, D. Scott Samuels, Claude F. Garon

Biological Sciences Faculty Publications

Coumermycin A1 is an inhibitor of DNA gyrase, an enzyme that catalyzes supercoiling of DNA and is required for bacterial DNA replication. We have investigated the activity of this coumarin antibiotic on Borrelia burgdorferi, a spirochete and the causative agent of Lyme disease. B. burgdorferi was more susceptible than many other eubacteria to coumermycin as well as novobiocin, another coumarin antibiotic; this contrasted with its relative resistance to the DNA gyrase inhibitors nalidixic acid, oxolinic acid, and ciprofloxacin. Coumermycin at 0.2 micrograms/ml inhibited the growth of B. burgdorferi B31 in BSK II medium. A 100-fold-lower concentration induced the relaxation of …

Speciation In Golden-Plovers, Pluvialis Dominica And P. Fulva: Evidence From The Breeding Grounds, Peter G. Connors, Brian J. Mccaffery, John L. Maron

Biological Sciences Faculty Publications

Two forms of golden-plover have long been considered subspecies, Pluvialis
dominica dominica and P. d. fulva. Prior studies have shown differences between forms in breeding distributions, wintering distributions, plumage, morphology, molt, and maturation schedules. We report clear and consistent differences in breeding vocalizations and nesting habitat, and strict assortative mating in areas of sympatry in western Alaska. These results indicate a greater degree of differentiation between the forms than was previously appreciated. They are appropriately treated as separate species and should be referred to under the names Pluvialis dominica, for the American Golden-Plover, and Pluvialis fulva, for …

A Few Steps Towards A More Quantitative Understanding Of Contrast In The Scanning Electron Microscope, F. Hasselbach, U. Maier

Scanning Microscopy

The interaction volume of the electron beam with the specimen in a scanning electron microscope (SEM) is a highly complex function of the surface structure of the specimen, its chemical composition and the energy of the scanning electron beam.· The video signals formed by secondary electrons (SE) or backscattered electrons (BSE) reflect this complexity insofar as they may contain not only information of the interior of the pixel which has just been scanned and its neighborhood, but may depend on surface details hundreds of microns apart from the impinging point of the electron beam. This leads to artifacts in scanning …

Applications Of Charge Collection Microscopy: Electron-Beam-Induced Current To Semiconductor Materials And Device Research, Richard J. Matson

Scanning Microscopy

Among all of the possible techniques for the micro-characterization of semiconductor materials and devices in a scanning electron microscope (SEM), charge collection microscopy (CCM), more commonly known as electron-beam-induced current (EBIC), is probably both the most easily deployed and the most versatile characterization technique. Following a brief review of the basic theory of the generation and detection of the EBIC signals, various techniques and applications to the micro-characterization of experimental semiconductor materials and devices will be presented. The applications are primarily to emerging photovoltaic materials and devices. This report is not in any way intended as a complete overview of …

Synchrotron Radiation Induced X-Ray Microanalysis: A Realistic Alternative For Electron- And Ion-Beam Microscopy?, K. Janssens, F. C. Adams, M. L. Rivers, K. W. Jones

Scanning Microscopy

Synchrotron radiation induced X-ray micro fluorescence analysis (μ-SRXRF) is compared with more conventional microanalytical techniques such as secondary ion microscopy (SIMS) and electron probe X-ray microanalysis (EPXMA) for two typical microanalytical applications. μ-SRXRF and EPXMA are employed for the analysis of individual particles, showing the complementary character of both techniques. By means of element mapping of trace constituents in a heterogeneous feldspar material, the strong and weak points of μ-SRXRF in comparison to EPXMA and SIMS are illustrated. The most striking difference between μ-SRXRF and the other two microanalytical methods is the ability of SRXRF to probe deep into the …

Influence Of Primary Electron Beam Angle Of Incidence On Auger Electron Spectra, Mark A. Smith

Scanning Microscopy

A principal step in the extraction of Auger electron yields and line shapes from electron-excited spectra is an understanding of the attendant electron background. Experiments are reported here in which the influence of the primary electron beam angle of incidence on Auger spectral backgrounds has been separated from that of the angle of electron emission. The secondary electron background for clean polycrystalline palladium, on the high-energy side of the MNN peaks, have been studied as functions of primary beam angle of incidence and beam energy. For the range of beam energies investigated, < 10 keV, linearization of the secondary cascade is easily observed in log-log plots of intensity versus energy. When cascades are fitted with Sickafus-type functions, AE^-m (E = electron energy), the parameter m …

Fractal Description Of Electron Scattering In Solids: Several New Results And A Simple Modelization Of The Fractal Dimension, Raynald Gauvin, Dominique Drouin

Scanning Microscopy

The fractal behaviour of electron scattering in solids is studied with electron trajectories simulated by Monte Carlo simulations. More precisely, the Hausdorff-Besicovitch dimension is determined for several electrons trajectories simulated in solids of different compositions. Then, a simple model to compute the fractal dimension of electron trajectories in solids is presented, a model which raises a question concerning the maximum value of the backscattering coefficient. Results of Monte Carlo simulations of electron trajectories in several elements with total randomness for the polar and azimuthal angles of scattering are presented as a tentative answer to this question. Finally, the multi fractal …