Biology Commons^™

Investigation Of Nanoparticles In High Resolution Scanning Electron Microscopy (Sem) And Low Voltage Sem By Digital Image-Analysis, B. Ocker, R. Wurster, H. Seiler

Scanning Microscopy

Small particles (Cu, Ag, In, Sn, Au, also MgO and NaCl) were prepared in the diameter range from 1 nm to 100 nm on different conductive substrates by thermal evaporation in high-vacuum or in an inert gas atmosphere. Imaging of the particles was performed in a high resolution scanning electron microscope (HRSEM) that can also be operated at low beam voltages of a few hundred volts. This mode of operation is called low voltage SEM (LVSEM). Scanning electron micrographs were taken at different beam voltages V_O (0.5-30 kV). The micrographs were digitally recorded and analyzed with an image processing …

High Resolution Electron Microscopy Of Enamel Crystallites Demineralized By Initial Dental Caries, Yoshihiko Hayashi

Scanning Microscopy

Acids produced by various oral bacteria cause mineral loss and crystallite dissolution during the development of enamel caries. In order to demonstrate this phenomenon, the initial disappearance of lattice fringes and the formation of a central perforation in crystallites were examined by high resolution electron microscopy (HREM) in initial enamel caries without macroscopic tissue evidence of destruction. Ultrathin sections were also examined by selected area electron diffraction to reveal the mineral phase of the surface layer in carious enamel.

A marked variation in the dissolution pattern was disclosed in the initial carious lesions. HREM revealed that disappearance of the lattice …

Controlling Influence Of Phosphocitrate In Vitro And In Vivo On Calcium Oxalate Crystal Formation And Growth, John D. Sallis, Nathan F. G. Parry, John D. Meehan, Harold Kamperman, Maree E. Anderson

Scanning Microscopy

Calcium oxalate (CaOx) crystallization in the presence of phosphocitrate (PC) was studied by both in vitro and in vivo techniques. Crystals of the monohydrate (COM) and the dihydrate (COD) forms were generated under controlled conditions in a silica gel matrix. Our data indicated only COD crystals formed when PC was present, inferring that the COD to COM transformation was being impeded. COD crystals were smaller in size than controls and there was evidence of interpenetral twinning. An in vivo study using a rat bladder implant model noted similar findings. Scanning electron microscopy (SEM) revealed that implants recovered from PC treated …

The Biogeochemistry Of Lakes In The Mount St. Helens Blast Zone, Victor Lee Menting

Dissertations and Theses

Dilution and ash weathering are the most important processes controlling the ion chemistry of lakes in the Mount St. Helens blast zone. Gibbs' models indicated total dissolved solids were decreasing as a result of dilution from high precipitation and runoff and the lakes plot in the rock weathering dominated region. Plots of theoretical dilution curves indicated a decline in ion concentrations as a result of dilution. Ion concentrations followed the exponential decline predicted by the dilution curve, although concentrations were higher than predicted by the curve. Increased concentrations were a result of the rapid weathering of ash in basins and …

Community Metabolism And Nutrient Cycling In The Mississippi River Plume: Evidence For Intense Nitrification At Intermediate Salinities, Joseph D. Pakulski, Ronald Benner, Rainer Amon, Brian Eadie, Terry Whitledge

Faculty Publications

Community respiration, net nutrient fluxes and heterotrophic bacterial production were investigated in the Mississippi River (USA) plume during May 1992 using dark bottle incubations of unfiltered water. Highest rates of community O₂ consumption and dissolved inorganic carbon regeneration were observed at intermediate (10 to 27%₀) plume salinities. Plume surface 0₂ consumption rates were 2- to 4-fold greater than rates reported previously during the summer and winter. Heterotrophic bacterial production ([³H]-leucine incorporation) was also highest at intermediate salinities and 2- to 4-fold greater than rates reported from other seasons. Net regeneration of NH₄^{+ …}

Reply To Nylin, Wickman & Wiklund Regarding Sex Ratios Of California Overwintering Monarch Butterflies, Dennis F. Frey, Kingston L. H. Leong

Biological Sciences

No abstract provided.

Phylogenetic Reanalysis Of Strauch's Osteological Data Set For The Charadriiformes, Philip C. Chu

Biology Faculty Publications

Strauch's (1978) compatibility analysis of relationships among the shorebirds (Charadriiformes) was the first study to examine the full range of charadriiform taxa in a reproducible way. Subsequently Mickevich and Parenti (1980) leveled serious charges against Strauch's characters, method of phylogenetic inference, and results. To account for these charges, Strauch's characters were re-examined and recoded, and parsimony analyses were performed on the revised matrix. A parsimony analysis on 74 taxa from the revised matrix yielded 855 shortest trees, each length = 286 and consistency index = 0.385. In each shortest tree there were two major lineages, a lineage of sandpiper-like birds …

Implications Of Native Title Legislation For Fisheries Management And The Fishing Industry In Western Australia, Patricia Summerfield

Fisheries Management Papers

This paper seeks to examine the key issues of both State and Commonwealth native title legislation for the fishing industry and fisheries management in Western Australia. Considerations for Aboriginal involvement in the industry and long-standing as well as recent concessionary arrangements for traditional usage of fish resources are examined. Industry reactions and future plans to accommodate native title in a positive framework are explored.

An Improved Method For Chemical Devitellinization Of X-Gal Stained Drosophila Embryos, Amit Singh, Madhuri Kango-Singh, P. Sinha

Biology Faculty Publications

In Drosophila developmental biological studies, X-gal staining is commonly employed to study the spatio-temporal expression of the lacZ reporter gene in the transformed flies or their embryos. Study of the lacZ pattern in embryos often suffers from the lack of an efficient and high yieldirrg technique for devitellinization of X-gal stained embryos. Devitellinization techniques employed during antibody staining, in situ hybridization or embryonic cuticular preparations generally do not give satisfactory results when used for similar purpose in X-gal stained embryos. This results in the flaky appearance of the blue stain. We present here an improved chemical devitellinization technique which gives …

Richard Goldschmidt's "Heresies" And The Evolutionary Synthesis, Michael Dietrich

Dartmouth Scholarship

No abstract provided.

Abundance And Diversity Of Aquatic Birds On Two South Texas Oxbow Lakes., Diane Teter, David L. Mcneely

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Avian use of two oxbow lakes located in urban surroundings of south Texas was studied for one year. Both abundance and diversity of aquatic birds were notably reduced in the more intensely developed area. Possible factors resulting in these differences are reviewed.

Revascularization Of An Excisional Wound In Gingiva And Oral Mucosa. A Scanning Electron Microscopic Study Using Corrosion Casts In Rats, Nils J. Selliseth, Knut A. Selvig

Scanning Microscopy

The purpose of this study was to examine microvascular regeneration associated with gingival wound healing. A full-thickness piece of gingiva and oral mucosa was excised along the palatal aspect of the right maxillary first and second molars in 20 young Wistar rats. The contralateral side served as unoperated control. After 2, 4, 7, 10 or 20 days of healing, microvascular corrosion casts were produced and examined by scanning electron microscopy. At 2 days, vessels surrounding the wound were dilated and impressions representing sites of leukocyte margination were prominent in the walls of venules. Capillary buds were emerging from venules and …

Scanning Electron Microscopy And Transmission Electron Microscopy Aspects Of Synergistic Antitumor Activity Of Vitamin C - Vitamin K3 Combinations Against Human Prostatic Carcinoma Cells, Jacques Gilloteaux, James M. Jamison, Meenaxi Venugopal, David Giammar, Jack L. Summers

Scanning Microscopy

A MTT/formazan assay was used to evaluate the antitumor activity of vitamin C (Vit C), vitamin K₃ (Vit K₃), or vitamin C:vitamin K₃ combinations against a human prostatic carcinoma cell line (DU145). Both Vit C and Vit K₃ alone exhibited antitumor activity, but only at elevated doses. When Vit C and Vit K3 were combined at a C:K₃ ratio of 100:1 and administered to the carcinoma cells, the 50% cytotoxic concentrations (CD50) of the vitamins decreased 10-to 60-fold. Subsequently, the DU145 cells were examined with transmission and scanning electron microscopy (TEM and SEM) following …

Experimental Calcium Oxalate Nephrolithiasis And The Formation Of Human Urinary Stones, Saeed R. Khan

Scanning Microscopy

Calcium oxalate nephrolithiasis in rats requires induction of hyperoxaluria which results in increased urinary calcium oxalate supersaturation. As a result of low to mild chronic hyperoxaluria, calcium oxalate crystals deposit first in the papillary collecting ducts. Crystal deposition in the kidneys is preceded by calcium oxalate crystalluria and starts with the retention of aggregated calcium oxalate crystals in the renal tubules. Retained crystals move from the tubules to the interstitium, and in the process, become anchored to the tubular basement membrane. Crystal aggregates present in the superficial peripheral collecting ducts of the renal papillae ulcerate through to the papillary surface …

Cathodoluminescence Of Rare Earth Doped Zircons. I. Their Possible Use As Reference Materials, F. Cesbron, P. Blanc, D. Ohnenstetter, G. Rémond

Scanning Microscopy

Synthetic zircon crystals (ZrSiO₄), undoped and doped with Y³⁺, La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, Yb³⁺, Lu³⁺, were grown from a flux consisting of a mixture of Li₂MoO₄ and MoO₃ heated to 1125°C and then cooled to 750°C. The cathodoluminescence (CL) spectra of these zircons were analyzed at room-temperature and near liquid nitrogen temperature with a CL spectrometer …

Diamond Luminescence, R. Heiderhoff, L. J. Balk

Scanning Microscopy

Luminescence spectroscopy is an established tool to investigate natural, high pressure synthesized, and chemical vapour deposited (CVD) diamond. The spectral range extends from 5.3 eV in the ultraviolet to approximately 1.2 eV in the near-infrared. More than 100 optical centres have been observed.

Since the early 1930's, semiconducting diamond for electronic devices has been of interest to science. The large bandgap (5.5 eV), low dielectric constant (5.7), and high thermal conductivity (about 5 times larger then that of Ag), as well as the superior charge-carrier transport properties, such as electron and hole mobility (µ^-: 2200 cm²/Vs, …

Temperature-Dependent Cathodoluminescence Spectroscopy And Microscopy As A Tool For Defect Identification In Semiconducting Ceramics: Application To Batio3 Ceramics, T. Hübner, U. Marx, J. Schreiber

Scanning Microscopy

Cathodoluminescence (CL) spectroscopy and microscopy were applied to investigate the characteristic grain-boundary contrast in semiconducting ferroelectric BaTiO₃ ceramics. It was shown, that "chemically clean" grain boundaries do not reveal any specific CL components neither in the visible nor in the infrared part of the spectrum. Instead, the contrast arises from at least two different non-radiative recombination centers present in the grain and the grain-boundary zones, respectively. Activation thresholds for these centers were determined from the temperature dependence of the integral CL signal down to 30K. The different values found explain the contrast reversal observed in BaTiO₃ ceramics upon …

A Phylogenetic Analysis Of Vertebrate And Invertebrate Notch-Related Genes, Eleanor M. Maine, James L. Lissemore, William T. Starmer

Biology - All Scholarship

Members of the Notch gene family are thought to mediate inductive cell-cell interactions during develop ment of a wide variety of vertebrates and invertebrates. These genes encode transmembrane proteins that appear to act as receptors and contain three repeated sequence motifs. Two of these motifs (an epidermal growth factor like sequence and a cdc10/SW16/ankyrin sequence) have been found in a large number of unrelated proteins, while the third motif (a lin-12/Notch/glp-1 sequence) is unique to proteins of the Notch family. We present a phylogenetic analysis of 17 Notch-related genes from eight species that has implications as to the origins and …

Enhancers Of Gzp1, A Gene Required For Cell-Signaling In Caenorhabditis Elegans, Define A Set Of Genes Required For Germline Development, Li Qiao, James L. Lissemore, Pei Shu, Anne Smardon, Melanie B. Gelber, Eleanor M. Maine

Biology - All Scholarship

The distal tip cell (DTC) regulates the proliferation or differentiation choice in the Cmorhabditis ekgans germline by an inductive mechanism. Cell signaling requires a putative receptor in the germline, encoded by the glp-1 gene, and a putative signal from the DTC, encoded by the lag-2 gene. Both glp-1 and lag-2 belong to multigene gene families whose members are essential for cell signaling during development of various tissues in insects and vertebrates as well as C. elegans. Relatively little is known about how these pathways regulate cell fate choice. To identify additional genes involved in the glp-1 signaling pathway, we carried …

Analysis Of The Multiple Roles Of Gld-I In Germline Development: Interactions With The Sex Determination Cascade And The Glp-1 Signaling Pathway, Ross Francis, Eleanor M. Maine, Tim Schedl

Biology - All Scholarship

The Caenorhabditis elegansgene gld-1 is essential for oocyte development; in gld-1 (null) hermaphrodites, a tumor forms where oogenesis would normally occur. We use genetic epistasis analysis to demonstrate that tumor formation is dependent on the sexual fate of the germline. When the germlines sex determination pathway is set in the female mode (terminal fem/fog genes inactive), gld-1 (null) germ cells exit meiotic prophase and proliferate to form a tumor, but when the pathway is set in the male mode, they develop into sperm. We conclude that the gld-1 (null) phenotype is cell-type specific and that gld-1 ( + ) acts …

The Effects Of Swimming Vs Running On Weight Loss In Small Mammals, David Ekkens, James Callan

Capstone Research Projects

No abstract provided.

Cathodoluminescence Of Rare Earth Doped Zircons. Ii. Relationship Between The Distribution Of The Doping Elements And The Contrasts Of Images, G. Rémond, P. Blanc, F. Cesbron, D. Ohnenstetter, O. Rouer

Scanning Microscopy

Cathodoluminescence (CL) color photographs using an optical CL microscope with a cold cathode electron gun are compared with non-spectrally resolved (polychromatic) and selected wavelength CL images obtained by means of a scanning electron microscope equipped with a CL spectrometer. It is the aim of this paper to show how the interpretation of the contrasts of CL images depends on the knowledge of the CL photon energy distributions participating to the observed contrasts as well as the matrix effects modifying the number of emitted photons compared to that of generated photons. It is shown that the impurities different from the rare …

Ultrafast Carrier Capture In Quantum Well Structures, P. W. M. Blom, J. E. M. Haverkort, J. Claes, P. J. Van Hall, J. H. Wolter

Scanning Microscopy

We present an experimental and theoretical study of the carrier capture time into a semiconductor quantum well. The carrier capture time was obtained by measuring both the rise of the quantum well (QW) population using time-resolved luminescence measurements and the decay of the barrier population using pump-probe correlation experiments. In the first technique, we compare the QW rise-times after direct (below the barrier band gap) and indirect (above the barrier band gap) excitation in order to eliminate the effects of relaxation and exciton formation in the quantum well.

We report the first experimental observation of oscillations in the carrier capture …

Optical Studies Of Ingaas/Gaas Multiple Quantum Wells (Mqw's) And Gaas/Si Using Novel Scanning Electron Microscopy Based Techniques, D. H. Rich, H. T. Lin, Y. Tang, K. Rammohan, A. Larsson

Scanning Microscopy

The influence of defects on electron-hole plasma transport in nipi-doped in _0.2Ga_0.8As/GaAs multiple quantum wells (MQWs) has been studied using a novel technique called electron beam induced absorption modulation (EBIA) imaging. Modulation doped MQW structures exhibit large optical nonlinearities and are important for the development of all-optical spatial light modulators used in optical computing and communication. The electron-hole plasma is generated by a high-energy electron beam in a scanning electron microscope and is used as a probe to study the MQW absorption modulation induced locally by the electron beam. The influence of structural defects on the …

Time-Resolved Luminescence From Two-Dimensional Electrons In High Magnetic Fields: A Tool For Studying The Fractional Quantum Hall Effect, Rolf J. Haug, Igor V. Kukushkin

Scanning Microscopy

Time-resolved magnetoluminescence investigations of specially doped AlGaAs/GaAs heterostructures allow the study of the electronic properties of two-dimensional electrons. The interactions of the two-dimensional electrons lead in high magnetic fields to the fractional quantum Hall effect. By analyzing the mean energy of the recombination line observed in the luminescence spectrum, the electronic properties of the fractional quantized states can be deduced. For negligible interaction between the charged acceptors and the interacting electron system, the derivative of the mean energy versus filling factor allows to obtain the jump of the chemical potential in crossing a fractional filling factor. From these jumps, the …

Genetic Structure Of Mosquitofish Populations In The Altamaha And Ogeechee Drainages Of Georgia: Reporting An Undescribed Form In The Ocmulgee River, Jose D. Hernandez-Martich, James M. Novak, Michael H. Smith, Paul E. Johns

Faculty Research & Creative Activity

An electrophoretic survey of genetic variation in mosquitofish populations of the Altamaha and Ogeechee drainages in Georgia revealed significant divergence (fs,=O.270) among populations within the Altamaha. Cluster analysis showed two lineages: one formed by populations from the Ogeechee drainage and the eastern and central Altamaha branches and another consisting of populations from the Ocmulgee River, the westernmost branch of the Altamaha drainage. These lineages may represent two independent forms. Average modified Rogers’ genetic distance was 0.25% between the two groups. The O_cmulgee lineage had significantly higher multilocus heterozygosity (H=0.206) than the other one (I-/=0.120). The high heterozygosity in the Ocmulgee …

Luminescence From Semiconductor Quantum Wires, Quantum Dots, And Monolayer Quantum Wells: Bottleneck And Localization Issues, C. M. Sotomayor Torres, P. D. Wang, N. N. Ledentsov, Y. -S. Tang, H. Qiang, F. H. Pollak, H. F. Ghaemi, B. B. Goldberg

Scanning Microscopy

Semiconductors nanostructures are fabricated using a range of techniques which inevitably have an impact in the resulting optical properties. Multilayers are grown by epitaxial techniques with a varying degree of uniformity in thickness, composition, etc., all leading to localisation effects in two-dimension. These multilayers are patterned to fabricate wires and dots using, in this case, electron beam lithography and dry etching. The fabrication steps contribute to modifications of the optical properties, beyond the expected purely confinement-related effects.

An overview of linear and modulation spectroscopy is presented to demonstrate the impact of fabrication steps as well as of lateral confinement upon …

Surface Recombination Velocity And Bulk Carrier Lifetime Measurement Of Silicon Crystals By Using Photoluminescence Time Decay, Karsten Thölmann, Masakazu Yamaguchi, Akihiro Yahata

Scanning Microscopy

The time decay for photoluminescence (PL) emitted from silicon crystals has been used to obtain both bulk carrier lifetime (Tb) and surface recombination velocity (S). Experimental results were interpreted with the assumptions that the sample was under a low-excitation condition and that the ratio of radiative to non-radiative recombination rates was constant throughout the carrier decay process. Analysis was applied to several wafers covered with different kinds of silicon dioxide (SiO₂). The results indicate that PL time decay measurement is effective to obtain the values of Tb and S.

Interpretation Of Cathodoluminescence Spectra Obtained From Dolomite And Calcite Gangue Minerals, And Dolostone Breccias In The Central Tennessee Zinc District (U.S.A.), Otto C. Kopp, E. Loren Fuller Jr., Michael R. Owen

Scanning Microscopy

Spectral patterns were obtained for zoned dolomite and unzoned calcite gangue, and dolostone breccia fragments from the Right Fork area in the central Tennessee zinc district (U.S.A.). The samples had been analyzed previously for Fe, Mn, and other trace elements using a synchrotron XRF probe. Spectra were obtained for zoned dolomite, breccia fragments, and unzoned calcite using an ELM2-B cold-cathode Luminoscope attached to an Oriel Multispec Compact Spectrograph. Spectra obtained for the prominent dolomite zones, which luminesce medium-bright to bright red to the eye, revealed a broad peak in the vicinity of 460 nm and a more intense peak in …

Ua66/6/3/1 Biennial Report, Kentucky Gamma, Alpha Epsilon Delta

Student Organizations

Biennial report created by and about the Kentucky Gamma Chapter of Alpha Epsilon Delta premedical honor society sponsored by WKU Biology.