Life Sciences Commons^™

Microbeam Studies Of The Sensitivity Of Structures Within Living Cells, L. A. Braby

Scanning Microscopy

Determining the biological effects of low doses of radiation with high linear energy transfer (LET) is complicated by the stochastic nature of charged-particle interactions. Populations of cells exposed to very low radiation doses contain a few cells which have been hit by a charged particle, while the majority of the cells receive no radiation damage. At somewhat higher doses, a few cells receive two or more events. Because the effects of damage produced by separate events can interact in the cell, we have had to make assumptions about the nature of these interactions in order to interpret the results of …

The Effect Of Colcemid On The Heat Survival Of Mitotic V79 Chinese Hamster Cells, J. G. Szekely, G. P. Raaphorst, A. U. Lobreau, S. Delaney, E. I. Azzam

Scanning Microscopy

V79 Chinese hamster cells were collected by colcemid addition to study the effect of heat on mitosis. When they were heated at 42°C and 45°C in the presence of 0.06 μg/mL colcemid, cell survival increased over the control samples, which were heated in ordinary medium. Scanning electron microscopy showed that cells heated to 45°C in the presence or absence of colcemid had fewer microvilli on the surface, but they did not have increased bleb formation. Transmission electron microscopy showed that the chromatin was diffuse in the heated cells and the kinetochores were indistinct. The mitochondria in the heated cells were …

A Review Of Scanning Tunneling Microscope And Atomic Force Microscope Imaging Of Large Biological Structures: Problems And Prospects, B. L. Blackford, M. H. Jericho, P. J. Mulhern

Scanning Microscopy

The application of the scanning tunneling microscope (STM) and the atomic force microscope (AFM) to the study of small biological molecules, such as DNA and smaller molecules, has received considerable attention in the literature. This paper reviews STM and AFM studies of larger biological structures such as bacterial membranes, bacteriophages, viruses, antibodies, etc. The problems encountered in these applications are emphasized, with particular reference to the unknown conduction mechanism, tip-sample interaction forces, and tip-sample convolution artifacts in the images. The latter problem is illustrated by new results from IgG antibody complexes attached to a bacterial sheath layer. A new conduction …

The Microvasculature Of Human Oral Mucosa Using Vascular Corrosion Casts And India Ink Injection I. Tongue Papillae, Q. X. Yu, W. Ran, K. M. Pang, H. P. Philipsen, J. Theilade, X. H. Chen, Y. C. Mok

Scanning Microscopy

The microvasculature of human tongue papillae originating from 9 males and 6 females, aged 0.5 to 2 years was studied by scanning electron microscopy (SEM) of vascular corrosion casts and by light microscopy (LM) of India ink injected specimens. All papillae showed a microvasculature characterized by primary, secondary and tertiary capillary loops. In the filiform papillae the loops were generally arranged in a corolla-like pattern with the tertiary loops demonstrating a hair-pin shape. The fungiform papillae showed basically a similar architectural pattern although the loops were somewhat more compact and complex in structure. A small, shallow depression of the tertiary …

Increasing Resolution And Versatility In Low Temperature Conventional And Field Emission Scanning Electron Microscopy, William P. Wergin, Eric F. Erbe

Scanning Microscopy

Studies were undertaken to expand the versatility and the resolution of low temperature conventional and field emission scanning electron microscopy (SEM). The results indicated that simple modified specimen holders, which could be used in conjunction with the commercial cryosystems, allowed one to store specimens for several weeks in liquid nitrogen, either before or after observation in a conventional SEM, without incurring degradation of the surface features. Other modified holders permitted one to move the specimen closer to the final lens or to use the upper secondary electron detector, which is available with some SEMs. Both of these procedures increased the …

New Directions In Scanning Electron Microscopy Cathodoluminescence Microcharacterization, D. B. Holt

Scanning Microscopy

The general principles of the low-temperature spectroscopic cathodoluminescence (LTSCL) technique in the scanning electron microscope (SEM) are outlined. CL microscopy and spectroscopy are now being extended in new directions. Analysis of the intrinsic CL from quantum well materials by LTSCL is proving valuable for microcharacterization and such work can be expected to expand rapidly. The main, early CL results in this exciting field are summarized here. In geology, CL microscopy, without spectroscopy, is widely used via electron-beam attachments to light microscopes and the addition of spectral analysis to these studies is overdue. Much CL from minerals and ceramics comes from …

Tooth Tissues Of Certain Sharks And Lungfishes, Yasutomo Iwai-Liao, Yoshikage Higashi, Yoshitaka Tamada

Scanning Microscopy

A comparative odontologic study was conducted on teeth and their supporting tissues from extant sharks, fossil sharks, and living lungfishes using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) X-ray microprobe to investigate evolutionary changes in tooth structure of the fishes.

No histological differences between the extant and fossil teeth of lamnoid sharks were observed. The weight percent of calcium in osteodentin of the fossil shark was higher than that in the extant shark. The weight percents of both P and Ca of tooth tissues in the giant extinct shark showed comparatively low values.

Both the upper and lower …

Calcium Oxalate Crystal Growth In The Presence Of Mucin, Mostafa Akbarieh, Rashad Tawashi

Scanning Microscopy

Using interfacially-controlled crystallization and gel diffusion crystallization methods, calcium oxalate monohydrate (COM), dihydrate (COD) and trihydrate (COT) crystals were grown by the slow diffusion of reacting ions in the presence of mucin. It was demonstrated that mucin in the growth media dramatically affected the size, habit, surface structure, thermodynamic stability and phase transition kinetics of hydrated calcium oxalate crystals. The results obtained revealed that mucin as a glycoprotein model controlled the growth of COT and COD single crystals as well as cluster formation. Growth inhibition of specific crystal faces and phase transition retardation occurred in its presence. The data confirmed …

Panchromatic And Spectral Characterization Of Cu Contaminated Semi-Insulating Gaas, Thomas E. Zirkle, Stephan Myhajlenko, Nam Soo Kang, Ronald J. Roedel, Dieter K. Schroder

Scanning Microscopy

Panchromatic (integral) and spectrally resolved cathodoluminescence characterization was used to investigate the near surface gettering properties of Cu in liquid-encapsulated, Czochralski-grown, undoped semi-insulating (SI) GaAs. Samples from two sources were investigated to determine if gettering treatments applied to GaAs result in improvements in uniformity similar to those observed in gettered Si. Before Cu contamination, typical cellular structure is observed for all samples. Experimentally, it is found that the panchromatic CL images change significantly after Cu doping and subsequent gettering processing for all samples. A contrast reversal is generally observed after Cu contamination. After gettering, the image of the samples from …

Epistomatal Wax Injury To Red Spruce Needles (Picea Rubens Sarg.) Grown In Elevated Levels Of Ozone And Acidified Rain, C. R. Krause, W. N. Cannon Jr.

Scanning Microscopy

Red spruce seedlings (Picea rubens Sarg.) were exposed to charcoal-filtered air, at 0.07 ppm or 0.15 ppm ozone (O₃), alone or in combination with pH 4.2 or pH 3.0 acidified rain, and examined with scanning electron microscopy (SEM) to determine if epistomatal wax fine structure was affected. Acidified rain in combination with 0.15 ppm O₃ produced changes in wax tubule morphology. Changes were moderate at pH 4.2 and severe at pH 3.0. Needles collected from Whiteface Mountain, New York, displayed injured epistomatal wax structure similar to that observed on needles exposed in the laboratory to 0.15 …

Optimization Design For The Electron Emission System Using Improved Powell Method, Chang-Xin Gu, Li-Ying Shan, Zhi-Rong Chen

Scanning Microscopy

The electron emission system, which may mostly decide the main properties of the whole electron optical system, is a crucial element for an electron gun. The design of the electron emission system is more important compared with other electron lenses in the electron gun. In this paper, an optimization design method for the electron emission system is presented by using an Improved Powell Method with linear search for the one dimensional search. The optimal structure parameters with a criterion of minimum objective function value for this system are provided. The computed results may show that this direct search optimization method …

Correlation Of Cochlear Pathology With Auditory Brainstem And Cortical Responses In Cats With High Frequency Hearing Loss, R. J. Mount, R. V. Harrison, S. G. Stanton, A. Nagasawa

Scanning Microscopy

Newborn kittens were treated with the aminoglycoside amikacin to produce a bilateral high frequency cochlear hearing loss. The degree and stability of hearing loss were confirmed by recording auditory brainstem evoked potentials (ABR audiograms). After maturation, cochleotopic frequency representation within primary auditory cortex (Al) was mapped using standard microelectrode recording techniques. The cochlear sensory epithelium was assessed with SEM and the pattern of damage compared with the ABR audiograms and cortical frequency maps.

Amikacin treatment resulted in various patterns of haircell damage towards the base of the cochlea. A relatively abrupt transition between damaged and undamaged haircell regions resulted in …

An Integrated Study Of The Morphological And Gross-Elemental Consequences Of Methyl Mercury Intoxication In Rats, With Particular Attention On The Cerebellum, K. Leyshon, A. J. Morgan

Scanning Microscopy

Methylmercury accumulates in the kidney and liver of rats, but fairly selectively damages the cerebellum, resulting in the clinical symptoms of neurological ataxia after prolonged exposures. Within the cerebellum, morphological examination indicated that the small granule cells beneath the Purkinje layer are especially susceptible to the toxin, showing signs of pyknosis during the phase of locomotory disability, whilst the large Purkinje cells are relatively resistant to cytotoxic injury. Flame photometric and electron probe X-ray microanalysis (EPXMA) of digested samples of the major organs failed to detect any significant changes in the Na, K, Ca, Mg, S and P concentrations of …

Application Of The Nuclear Microprobe To The Imaging Of Single Event Upsets In Integrated Circuits, K. M. Horn, B. L. Doyle, D. S. Walsh, F. W. Sexton

Scanning Microscopy

A new form of microscopy has been developed which produces micron-resolution maps of where single event upsets occur during ion irradiation of integrated circuits. Utilizing a nuclear microprobe, this imaging technique can irradiate, in isolation, individual components of an integrated circuit (e.g. transistor drains, gates, feedback resistors) and measure immediately the effect of a high energy ion strike on circuit performance. This detailed circuit characterization technique provides a precision diagnostic with which to evaluate the design of integrated circuits that are to be used in space or other radiation environments.

Surface Topographical And Compositional Characterization Using Backscattered Electron Methods, Dirk A. Wassink, Jerry Z. Raski, Joel A. Levitt, David Hildreth, Kenneth C. Ludema

Scanning Microscopy

Two pairs of diametrically opposed Schottky surface barrier diodes in a modified scanning electron microscope (SEM) are used to reconstruct surface elevations and composition differences. An empirically determined function of difference of signals from opposing diodes is used to calculate slopes, which are then integrated to elevations by an efficient 2-dimensional Fast Fourier Transform. Composition differences are distinguished by variations in the overall backscattered electron (BSE) intensity estimated by the sum of the four diode signals. Arithmetic average roughness measurements from the BSE device are within 10% of stylus surface tracer measurements when surface slopes average less than 6 degrees …

Microscopy Of Mixed Surfaces On Layered Semiconductors, L. Margulis, D. Mahalu, B. Parkinson, R. Tenne

Scanning Microscopy

A large number of well-defined hexagonal etch pits is produced on the WSe₂ surface by controlled anisotropic corrosion. As a result a mixed surface (combining both ⊥c and ||c components) is created. This surface exhibits photovoltaic properties even better than the atomically smooth van der Waals surface. Measurements of electron beam induced current performed at low temperatures give direct evidence for enhanced current collection of ||c facets. Observations made by transmission electron microscopy and scanning tunneling microscopy show the presence of very low ||c steps on the van der Waals surface.

Seed Testa Morphology Of 18 Species Of Rafnia Thunb. (Fam. Fabaceae, Sub-Family Papilionoideae), G. R. Richardson, R. Cross

Scanning Microscopy

Scanning electron microscopy was used to conduct a micromorphological study of testae of the seeds of 18 species of Rafnia Thunb. (Fam. Fabaceae, Sub-family Papilionoideae). The testa patterns revealed diagnostic taxonomic features which proved useful in the construction of a key for the identification of the various Rafnia species. Comparisons between air-dried freshly collected, and long-term stored herbarium specimens revealed that testa patterns remained consistent and valid for taxonomic purposes.

Electron Beam Induced Current Investigations Of Electrical Inhomogeneities With High Spatial Resolution, Eu. Yakimov

Scanning Microscopy

Electron beam induced current (EBIC) microscopy is a very promising SEM technique for the study of diffusion length and depletion region width inhomogeneities with high spatial resolution. However, this resolution is limited by the dimensions of the electron-hole pair generation region. In this paper the possibilities to improve spatial resolution are discussed. Electron beam tomography, i.e. the reconstruction of physical property distributions from sets of two-dimensional images, seems to be the most promising for this purpose. It is shown that in the case of dislocations it is possible to obtain information about dislocation impurity atmosphere parameters from EBIC measurements. The …

Micro-Pixe (Particle-Induced X-Ray Emission Analysis) Applications In Minerals Research, S. H. Sie, C. G. Ryan, G. F. Suter

Scanning Microscopy

The versatility of the PIXE method with microbeams of protons as a non-destructive, in-situ probe for trace element analysis in the geosciences has been demonstrated in an ever increasing number of cases. While in most applications the method can be considered as derivative or as an extension of electron microprobe methodology, features unique to the proton microprobe enable new approaches to hitherto intractable problems of analysis. An appropriate niche has been established in igneous mineralogy and petrology, with important implications both in the basic geosciences as well as mineral industry applications, particularly in the diamond exploration industry. This paper reviews …

The Development Of The Vascular System In Quail Embryos: A Combination Of Microvascular Corrosion Casts And Immunohistochemical Identification, M. C. Deruiter, B. Hogers, R. E. Poelmann, L. Vanlperen, A. C. Gittenberger-De Groot

Scanning Microscopy

Although vascular casts, obtained by injection with methacrylates, are frequently used to investigate the adult vascular system, little data are available for embryonic stages. In this paper we use Mercox^R in quail embryos in the period of 2 to 7 days after incubation. The microvascular corrosion casts were evaluated in the scanning electron microscope (SEM) with special attention to the development and remodelling of the large arteries and veins. Our results show that the remodelling of the large arteries and veins together with their developing tributary vessels can be visualized from very early embryonic stages onwards. However, complete replication …

Cellular Basis Of Aging In The Mammalian Heart, Piero Anversa, Joseph M. Capasso

Scanning Microscopy

This review is concerned with the functional and structural changes occurring in the aging heart. These changes were investigated in an integrated fashion in Fischer 344 rats at 4, 12, 20, and 29 months after birth. Mean arterial pressure, left ventricular systolic and end-diastolic pressures, as well as stroke volume remained substantially constant up to 20 months. At 29 months, however, end-diastolic pressure was significantly increased, and dP/dt and stroke volume were depressed. Focal areas of interstitial and replacement fibrosis were markedly increased at 20 and 29 months, mostly in the subendocardial region of the ventricular wall. Also the aggregate …

Microphotometric Quantification Of Crystal Growth In Gels For The Study Of Calcium Oxalate Urolithiasis, Wolfgang Achilles

Scanning Microscopy

This paper gives a review on an efficient microtechnique (Gel Crystallization Method; GCM) which quantifies crystal growth in gel matrices, and its application to research into urinary stone formation. Relative crystal growth rates (Vcr) of calcium oxalate hydrates (CaOx) were determined by simultaneous multiple measurements in 96-well microplates using computer controlled microscopic photometry. Efficiency: 120 kinetic measurements/h; imprecision: < 2% at standard conditions. The method was applied to study the effects of diverse small-ionic and macromolecular constituents of human urine on the crystal growth rate of CaOx. The 'inhibitory activity' of urine could be evaluated by comparison of the Vcr measured in native and corresponding artificial samples. Macromolecules, at physiological concentration, played only a minor role as inhibitors in the model under regard. The GCM was employed to study the in-vivo effects of different therapeutic measures on CaOx growth in urine of normal volunteers. While the application of alkali citrate resulted in a > 70% decline of Vcr, no beneficial effects could be found with three magnesium compounds, and a dietary fiber preparation. In a study including 20 male recurrent CaOx stone formers and 29 well-matched controls, among all parameters under investigation, the Vcr showed the …

Scanning Electron Acoustic Microscopy And Scanning Electron Microscopic Imaging Of Iii-V Compounds Devices, J. F. Bresse

Scanning Microscopy

Scanning electron acoustic microscopy (SEAM) and SEM infrared imaging (SEMIR) use both a modulated electron beam to generate thermal waves which produce acoustic waves detected by a transducer in the case of SEAM and affect the surface temperature which is directly monitored by the infrared emission. Both techniques are used to visualize non-adherence zones in III-V compounds devices. SEAM is applied to metallic layers like Au, Au-Ti, W-Mo-Ge deposited on a GaAs substrate. SEAM images are correlated with global adherence measurements.

SEMIR is applied to dielectric layers, like Si₃N₄/InP. An estimation of the surface temperature is …

The Role Of The Spleen In Lymphocyte Migration, R. Pabst, J. Westermann

Scanning Microscopy

In all species studied so far it was found that more lymphocytes migrate to the spleen than to all the lymph nodes together. Specific molecules on lymphocytes and endothelial cells regulate their entry into lymph nodes, but none of the known molecules play a role in homing to the spleen. The splenic compartments, comprising the red pulp, marginal zone, periarterial lymphatic sheath (PALS) and follicles, all show different kinetics for migrating lymphocytes. By combining ⁵¹Cr lymphocyte labeling with morphometry and two color immunohistochemistry, the migratory route of lymphocyte subsets can be followed through the spleen and absolute numbers of …

Sphincters In The Rat Pulmonary Veins. Comparison Of Scanning Electron And Transmission Electron Microscopic Studies, S. Aharinejad, P. Böck, A. Lametschwandtner, P. Franz, W. Firbas

Scanning Microscopy

The microvasculature of the rat lung was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) of vascular corrosion casts and tissue sections. Particular emphasis was placed on postcapillary venules, pulmonary venules and small pulmonary veins (small interlobular veins).

Casts of lung capillaries appeared inconspicuous with smooth surface. On the casts of pulmonary venules and small pulmonary veins, by contrast, series of narrow annular constrictions, present at regular distances of 20-25 μm, were seen. These constrictions may be drastic, narrowing down the caliber of the vessel up to 50%. In the constrictions the marks of circularly running tubular …

Microvascularization Of The Pleura In Rats And Guinea Pigs, S. Aharinejad, A. Lametschwandtner, P. Böck, P. Franz

Scanning Microscopy

The microvascularization of the visceral and parietal pleura was studied in rats and guinea pigs using vascular corrosion casts and scanning electron microscopy.

The visceral pleura was shown to be devoid of a vascular bed of its own. The capillary meshwork observed on the surface of the lung belongs to the pulmonary parenchyma. The parietal pleura, by contrast, possesses its own capillary network with an appropriate arterial supply and a venous drainage. The parietal pleural capillaries cover the costal regions completely, whereas the intercostal spaces are only provided by interspersed small patches of capillaries. That the feeding arteries of the …

The Matrix Of Urinary Tract Stones: Protein Composition, Antigenicity, And Ultrastructure, J. P. Binette, M. B. Binette

Scanning Microscopy

We have extracted proteins from urinary tract stones by electrodialysis and have developed antisera to the core and the shell of a renal stone. The protein composition varies between stones but is identical in the core and the shell of the same stone. One stone antigen is present in the urine of normal individuals and stone formers, as well as in cholesterol gallstone extracts. Electron microscopy of the core of a urate-calcium oxalate stone before and after demineralization reveals a fibrillar structure associated with mineral deposits, as well as aggregates of crystals.

A Theory And Monte Carlo Calculation On Low Energy Electron Scattering In Solids, Yen-Cai Ho, Zheng-Yu Tan, Xin-Lei Wang, Jia-Guang Chen

Scanning Microscopy

Low energy electron scattering (LEES) courses in solids are described by using a strict theory and direct simulation method proposed in this paper: we have improved Pendry's method based on the partial wave expansion, which can be applied to calculate the elastic scattering between an electron and atoms. The contributions of shell electrons, conductive electrons and plasma excitations are considered in the calculation of the inelastic scattering; electron scattering and cascade process of secondary electrons are simulated by Monte Carlo method. The secondary electron yields, the energy spectra curve and the backscattering electron coefficients for Cu were evaluated at the …

Scanning Tunneling Microscope Images Of Adenine And Thymine At Atomic Resolution, M. J. Allen, M. Balooch, S. Subbiah, R. J. Tench, W. Siekhaus, R. Balhorn

Scanning Microscopy

The scanning tunneling microscope has been used to obtain images of DNA that reveal its major and minor grooves and the direction of helical coiling, but sufficient resolution has not yet been achieved to identify its bases. To determine if this technology is capable of identifying individual DNA bases, we have examined the molecular arrangements of adenine and thymine attached to the basal plane of highly oriented pyrolytic graphite. Both molecules form highly organized lattices following deposition on heated graphite. Lattice dimensions, structural periodicities, and the epitaxy of adenine and thymine molecules with respect to the basal plane of graphite …

The Effect Of Bacterial Endotoxin Upon The Morphology Of The Tectorial Membrane And Stereocilia In The Guinea Pig Cochlea, S. D. Comis, M. P. Osborne, M. J. Tarlow

Scanning Microscopy

Endotoxin of E coli was microperfused into scala tympani or injected into the cerebrospinal fluid in anaesthetised pigmented guinea pigs. The effects of endotoxin on the cochlea were studied using electrophysiological techniques and scanning electron microscopy. We found a drop in the amplitude of the cochlear microphonics and compound action potentials 2 to 2.5 hours after injection. There were also changes in the morphology of stereocilia and the tectorial membrane. The stereocilia lost their rigidity and the tectorial membrane appeared swollen. These effects were less severe in animals which were pretreated with dexamethasone.