Life Sciences Commons^™

Early Phase Changes During The Setting Of High Copper Amalgams, T. Ruzickova, J. Had

Scanning Microscopy

X-ray diffraction analysis has been used to evaluate the phase composition of two (spherical and lathe cut) HCSC amalgam alloys and early phase changes in these amalgam in the time interval 2.5 min to 7 days after trituration. A method appropriate for the evaluation of these changes was developed. Only two phases were found in alloys Valiant and Ana 2000: gamma(Ag₃Sn) and epsilon(Cu₃Sn). In amalgams, no diffraction peaks were observed corresponding to gamma 2 phase in the time interval form 2.5 min to 7 days after trituration. The relative concentration changes of the reaction products of …

A Simulation Of Secondary Electron Trajectories In Solids, M. Kotera, T. Kishida, H. Suga

Scanning Microscopy

A Monte Carlo calculation model is introduced to simulate not only the primary electron behavior but also the secondary electron cascade in a specimen bombarded with an electron beam. Electrons having energy greater than 0.1keV are treated as "fast electrons" and the single scattering Monte Carlo model is adopted. Electrons having energy smaller than 0.1keV are treated as "slow electrons" and the electron cascade Monte Carlo model is used. The calculated results for the energy distribution of secondary electrons, and primary electron energy dependence of the total secondary yield and the backscattering yield are in good agreement with experimental results.

Strontium And Bromide As Tracers In X-Ray Microanalysis Of Biological Tissue, Joanna Wroblewski, Samuel Sagström, Helmy Mulders, Godfried M. Roomans

Scanning Microscopy

Since energy dispersive X-ray microanalysis cannot distinguish between isotopes of the same element, alternative methods have to be used to get information similar to that obtained in experiments with radioactive tracers. In the present study, strontium was used as a tracer for calcium, and bromide as a tracer for chloride. Rats were injected with strontium chloride in vivo, and the uptake of strontium in the acinar cells of the submandibular gland was studied. Eventually a Sr/Ca ratio of 0.3 was reached. In some animals, secretion of mucus had been elicited by stimulation with isoproterenol 4 h prior to injection …

Backscattered Electron Imaging Using Single Crystal Scintillator Detectors, R. Autrata

Scanning Microscopy

The image obtained by the detection of backscattered electrons (BSE) becomes an indispensable complement to the correct interpretation and more precise reconstruction of the surface of the specimen and its material composition. The BSE are carriers of information which is dependent on their angular and energy distribution. The choice of a certain type of BSE and their efficient detection make it possible to record the desired information with a different grade of quality. The knowledge of the angular and energy distribution of BSE is necessary for the adjustment of the correct position of the BSE detector with regard to the …

Bone Lining Cells: Structure And Function, Scott C. Miller, Louis De Saint-Georges, Beth M. Bowman, Webster S. S. Jee

Scanning Microscopy

Bone lining cells (BLC's) cover inactive (nonremodeling) bone surfaces, particularly evident in the adult skeleton. BLC's are thinly extended over bone surfaces, have flat or slightly ovoid nuclei, connect to other BLC's via gap junctions, and send cell processes into surface canaliculi. BLC's can be induced to proliferate and differentiate into osteogenic cells and may represent a source of "determined" osteogenic precursors. BLC's and other cells of the endosteal tissues may be an integral part of the marrow stromal system and have important functions in hematopoiesis, perhaps by controlling the inductive microenvironment. Because activation of bone remodeling occurs on inactive …

Practical Aspects Of Automatic Orientation Analysis Of Micrographs, N. K. Tovey, P. Smart, M. W. Hounslow, X. L. Leng

Scanning Microscopy

Techniques to analyse the orientation of particulate materials as observed in the scanning electron microscope are reviewed in this paper. Emphasis is placed on digital imaging, processing, and analysis methods, but many secondary electron images are not amenable to traditional image processing as adequate thresholding is often difficult to achieve. Evaluation of the intensity gradient at each pixel offers an alternative approach, and this method is described in detail including the latest developments to generalize the technique. Practical points in the acquisition, processing and analysis of the images are considered and several images, including both synthetically generated and actual back-scattered …

Osteoclast Features Of Cells That Resorb Demineralized And Mineral-Containing Bone Implants In Rats, Cedo M. Bagi, Scott C. Miller

Scanning Microscopy

The comparative temporal tissue response to demineralized bone matrix powder (DBP) and devitalized mineral containing bone powder (MCP) implanted subcutaneously in rats was studied. The tissue response to implanted DBP followed the well described endochondral osteogenic pathway and included the appearance of osteoblasts and osteoclasts. On the other hand, implanted MCP resulted in the appearance of a large population of giant cells that resorbed the implants. At later times (3-4 weeks), most of the cells in the MCP implants appeared as typical foreign body giant cells with extensive membrane foldings, usually away from bone surface. Some cells did, however, have …

Structural And Compositional Changes In Aging Bone: Osteopenia In Lumbar Vertebrae Of Wistar Female Rats, M. Silbermann, M. Safadi, D. Schapira, I. Leichter, R. Steinberg

Scanning Microscopy

Changes in vertebral bone mineral content and density during aging were quantified in female Wistar rats. This study represents a longitudinal follow up utilizing single photon absorptiometry for the measurement of bone mineral content (BMC), quantitative computed tomography (OCT) for the measurement of bone mineral density (BMD), and image analysis histomorphometry for the measurement of trabecular bone volume (TBV) and bone cortical area (BCA). The above measurements were accompanied by biochemical assays of calcium concentrations in the respective bones. All aging animals experienced significant decreases in BMC, BMD, TBV, BCA and in the calcium content of their bones. The above …

Bacillus-Shaped Deposits Composed Of Hexahedrally Based Crystals In Human Dental Calculus, T. Kodaka, A. Hirayama, K. Miake, S. Higashi

Scanning Microscopy

In human supra- and subgingival calculus, bacillus-shaped deposits showing various rocky-pile forms composed of hexahedrally based crystals were observed by scanning electron microscopy. The crystal size measured approximately 0.1 - 1.5 μm. The electron probe microanalysis always detected calcium, phosphorous, and magnesium. Their molar ratios resembled those of magnesium-containing whitlockite and moreover the crystals also gave the electron diffraction pattern of whitlockite. The bacillus-shaped deposits happened to coexist with the intracellular calcifying microorganisms, furthermore, oral microorganisms partially replaced by the hexahedrally based crystals were found. The crystal deposits were never seen in the surface layers of calculus exposed to the …

Microprobe Analysis Of Element Distribution In Bovine Extracellular Matrices And Muscle, M. B. Engel, H. R. Catchpole

Scanning Microscopy

The concentrations of some essential elements, Na, K, P, S and Cl were determined by microprobe analysis in bovine extracellular matrices of cartilage, tendon and elastic tissue (ligamentum nuchae) and in muscle cells. The values for the different tissues were compared and related to the blood electrolyte concentrations. Among the connective tissues the highest Na and lowest Cl values were found for cartilage which bears a high negative charge. The lowest concentrations of these elements occurred in elastic tissue which is relatively non-polar. In the three extracellular matrices sodium levels exceeded potassium. In myofibers potassium was the major cation at …

Data Acquisition And Presentation In Scanning Nuclear Microprobe Analysis, K. G. Malmqvist, N. E. G. Lövestam, J. Pallon, U. A. S. Tapper

Scanning Microscopy

The data acquisition is a very important part of the scanning nuclear microprobe instrument. To make full use of the potential of the technique an adequate system for acquiring, storing, processing and presenting the data is a prerequisite. Various principles applied are presented including the list mode approach, which facilitates flexible off-line data processing. As in the case of the electron probe the beam-induced effects in the sample may be substantial and the list mode acquisition can then also be used to monitor and correct for any such effects. A comprehensive system for scanning nuclear microprobe control and data acquisition, …

Quantitative Measurement From Vascular Casts, Ralph G. Kratky, Christine M. Zeindler, Dorian K. C. Lo, Margot R. Roach

Scanning Microscopy

A review of quantitative measurements show casting materials shrink from 0.2 - 20% and have viscosities ranging from 1.4 - 100,000 centipoise. Blood vessels have highly variable mechanical properties. Some microvessels are very stiff having little change in dimensions with pressure. Larger vessels generally change diameter significantly but show highly variable changes in length with pressure. Perfusion fixation does not fix the dimensions of blood vessels. Dog carotid arteries well fixed with glutaraldehyde at physiologic dimensions retain ≈20% of their elastic recoil circumferentially and ≈30% longitudinally. We recommend vascular casting as a method of accurately measuring the vasculature if care …

Oxalate Crystallization In The Kidney In The Presence Of Hyperuricemia, Shinshi Noda, Kenichi Hayashi, Kousaku Eto

Scanning Microscopy

It has been a long time since uric acid was suggested to be a promoting factor in calcium oxalate stones, and a number of in vitro studies have been carried out on the relationship between uric acid or urate and calcium oxalate.

Concerning in vivo studies, urate or calcium oxalate stone-forming diets were given alone in most cases, and diets that induce formation of stones with different composition have not been given in combinations. We administered a low-concentration oxalemic diet, and a mixed diet containing oxalic acid and uric acid, and biochemically and histologically studied the effects of oxalate and …

Surface Heterogeneity Of Tumor Cells And Changes Upon Ionizing Radiation, Z. Somosy, Orsolya Csuka, Tamara Kubasova, J. Kovács, G. J. Köteles

Scanning Microscopy

Heterogeneous distribution of surface domains is a characteristic feature of the tumor cell surface and the distribution differs from that of normal cells. During the malignant transformation the heterogeneity may change or disappear. Cell lines with various metastasizing capacities show different distributions of membrane domains or other differences in membrane or surface organization. We have demonstrated that the amount and distribution of negatively charged sites of B 16 melanoma membranes changed upon ionizing radiation (X-ray, ⁶⁰Co-gamma). In the case of the P 388 lymphoma, however, only the amount of negatively charged sites change after irradiation, the distribution remains unaltered. …

The Physical State Of Potassium In The Human Lymphocyte: A Review, William Negendank

Scanning Microscopy

Studies of the effects of chemical potential, temperature, and metabolic perturbation on static ion contents, kinetics of the approach to equilibrium, and kinetics of ionic self-exchange in human lymphocytes are reviewed. The results contradict the classical concept of cell ion and water physiology, the membrane-osmotic, pump-leak theory, and are re-interpreted by an adsorption model of the cell. In this model, most of cell water exists in a physical state sufficiently ordered to reduce the partition function of dissolved ions, and most of cell potassium is associated with fixed charges on macromolecules. Competing adsorption of potassium and sodium is cooperative and …

Gastrointestinal Surface Changes: Interpretation Problems And Indexing Possibilities (A Review), C. J. Pfeiffer, O. Bulbena

Scanning Microscopy

The purpose of this review on state-of-the-art and new perspectives on the use of scanning electron microscopy (SEM) in gastrointestinal pathology is to discuss the possibility of developing an index for quantitatively grading mucosal epithelial injury. This topic is reviewed within the framework of ulcer indices previously developed for gross lesions, where analogous problems exist, and in relation to the transmission electron microscope staging of epithelial cell pathology. If such an index could be developed it would increase objectivity and standardization of data analysis from laboratory to laboratory, and would allow for quantitative and statistical analysis of morphometric data. It …

Scanning Tunneling Microscopy And Fabrication Of Nanometer Scale Structures At The Liquid-Gold Interface, J. Schneir, H. H. Harary, J. A. Dagata, P. K. Hansma, R. Sonnenfeld

Scanning Microscopy

The Scanning Tunneling Microscope (STM) can image gold surfaces covered with a variety of liquids. This paper reviews the results obtained using the STM to image gold surfaces covered with liquid. These results include the creation of 10 nm structures, images of the electrochemical process of electroplating, and the production of atomically flat Au (111) surfaces. We conclude that in the future STM will find further application in the area of nanostructure fabrication and electrochemistry. The trend in the field is toward greater control of the electrochemical environment.

Morphology And Chemical Composition Of Dental Calculi Mainly Composed Of Whitlockite, Toshiro Sakae, Hirotsugu Yamamoto, Hiroyuki Mishima, Takashi Matsumoto, Yukishige Kozawa

Scanning Microscopy

The morphology and chemical composition of two subgingival calculus samples, which were composed of magnesium-whitlockite with a Mg/Ca molar ratio of approximately 0.1 as shown by X-ray powder diffraction, were analyzed semiquantitatively using energy-dispersive spectroscopy (EDS) combined with scanning electron microscopy (SEM). The Ca/P molar ratio values for 33 EDS-analyzed materials ranged from 1.24 to 2.03 with an average of 1.49, and the (Mg+Ca)/P molar ratio values ranged from 1.43 to 2.28 with an average of 1.63. The average Mg/Ca molar ratio was 0.10, a value very close to that obtained by X-ray diffraction analysis.

The EDS-analyzed materials were grouped …

Cation Nuclear Magnetic Resonance (Nmr). 7li- And 23na-Nmr Results Obtained With Human Erythrocytes, Jan F. M. Post

Scanning Microscopy

A short discussion of practical results and theoretical aspects of nuclear magnetic resonance (NMR) on intracellular monovalent cations is presented. ⁷Li- and ²³Na-NMR relaxation studies on human erythrocytes are described which indicate that lithium and sodium ions are essentially free inside the cell. However, there is a contribution to transverse relaxation originating from cations diffusing through electric field gradients imposed by the cytoskeleton, which is reflected in the NMR line shape. ³⁹K-NMR results obtained by other authors for intracellular potassium are compared with the ⁷Li- and ²³Na-NMR results presented here. The few ³⁹K-NMR results …

Simultaneous Micro-Characterization Of The Superconducting And Structural Properties Of High-Tc Superconducting Films, R. P. Huebener, R. Gross

Scanning Microscopy

Important information on the local values of the critical temperature and the critical current density in high-T_c superconducting films is obtained by low-temperature scanning electron microscopy (LTSEM). The imaging principle of LTSEM is based on the local beam-induced heating effect and the detection of a voltage response signal in the current-biased specimen film. During the scanning process the sample is mounted on a low-temperature stage the temperature of which is electronically stabilized at some specific value in the range of interest. The local superconducting quantities measured by LTSEM can be correlated with the microstructure of the specimen film investigated …

Microscopy Analysis Of Dental Titanium Casting Investment Materials, H. J. Mueller

Scanning Microscopy

Scanning electron microscopy (SEM) analysis and qualitative energy dispersive x-ray microanalysis (EDS) of investment materials for dental titanium casting were performed. Two commercial investment materials, Ohara and Castmatic, and an experimental zirconia material were analyzed. The microstructural constituents and the unfired and fired structures were included. Larger refractory particles and matrix embedding smaller particles were observed with each material. Detection of aluminum, silicon, magnesium, zirconium and oxygen provided a basis to reason the presence of alumina (Al₂O₃), silica (SiO₂), magnesia (MgO), and zirconia (ZrO₂). Hence, Ohara contained quartz and an alumino-silicate, Castmatic …

Scanning Electron Microscopy Of Lung Following Alpha Irradiation, C. L. Sanders, K. E. Lauhala, K. E. Mcdonald

Scanning Microscopy

Pulmonary aggregation of inhaled ²³⁹PuO₂ particles leads to a cellular evolution of focal inflammation, fibrosis, epithelial dysplasia and lung tumor formation. Female Wistar rats were exposed to an aerosol of high-fired ²³⁹PuO₂ (initial lung burden, 3.9 kBq) and the lungs examined at intervals from 1 day to 700 days after exposure by light and scanning electron microscopy and autoradiography. Peribronchiolar Pu particle aggregation increased with time, resulting in well-defined focal inflammatory lesions after 120 days and fibrotic lesions after 180 days. A generalized hypertrophy and hyperplasia of nonciliated bronchiolar cells was seen at 15 days and …

Biuret Staining And X-Ray Microanalysis For Locating Grafted Poly(Methyl Acrylate) On Wool Fibers, R. R. Bresee, P. A. Annis

Scanning Microscopy

Biuret reagent was used to stain wool fibers with copper so the location of a small amount of poly(methyl acrylate) grafted onto the fibers could be determined by energy dispersive x-ray microanalysis of copper. The grafted polymer was determined to be located in regions of the fibers where cuticle had been previously damaged. The amount of grafted polymer present was too small for secondary electron imaging to be useful for locating the polymer grafts.

Dendritic Oxide Growth On The Surface Of Liquid Gallium, Y. L. Wang, A. Raval, R. Levi-Setti

Scanning Microscopy

We have studied the oxidation of a liquid gallium surface with a high spatial resolution scanning ion microprobe. A 40 keV focused gallium ion beam, extracted from a liquid metal ion source, was employed, first, to sputter clean a 40 x 40 μm² area on a drop of liquid gallium, in a ultra high vacuum (UHV) specimen chamber. It was then used to monitor the oxide growth by secondary ion mass spectrometry imaging microanalysis while the chamber was gradually back-filled with oxygen. In the initial stages, gallium oxide grew in a dendritic pattern from the edge of the cleaned …

Analysis Of Insulator Samples By Secondary Neutral Mass Spectrometry, Hans Oechsner

Scanning Microscopy

Secondary Neutral Mass Spectrometry (SNMS) offers new possibilities for the analysis of insulators when the electron component of the postionizing SNMS plasma is employed for a precise compensation of sample charging. The compensation techniques for the three operation modes of SNMS, namely the direct, the separate and the external bombardment mode are described. Corresponding examples for bulk and depth profile analysis of insulating samples and dielectric thin film systems will be reported and discussed.

Surface And Grain Boundary Analysis Of High Temperature Superconductors, F. J. Himpsel, A. G. Schrott

Scanning Microscopy

The purpose of this paper is to survey the methods that are available for probing surfaces and grain boundaries of high temperature superconductors. Various surface-sensitive spectroscopies are applied to the analysis of YBa₂Cu₃O_7-x and Bi₂Sr₂CaCu₂O_8+x including photoelectron spectroscopy, spatially-resolved electron energy loss spectroscopy, and scanning electron microscopy (SEM). One of the major sources of contamination at surfaces and grain boundaries is found to be BaCO₃. The cleavage surface of single crystal Bi₂Sr₂CaCu₂O_8+x is inert and can be used to …

A Calculation Method Of X-Ray Emitted Intensity In Multi-Layer Films By Monte Carlo Simulation, Yen-Cai Ho, Jia-Guang Chen, Xin-Lei Wang

Scanning Microscopy

A calculation method of X-ray emitted intensity in multi-layer films is proposed in this paper. The method is based on the work developed by us: (1) a simplified physical model of electron scattering and Monte Carlo evaluations in a single medium and in multi-layer media and (2) the theories and the formulae for excitation, absorption and fluorescence of characteristic X-rays. The intensity ratio of X-rays for the known thickness films, Au/Cu/Si and Cr/Ni/Si, were calculated at 20, 25 and 30 keV. Calculated results are compared with experimental values of electron microprobe analysis for the multi-layer film specimens, and the correspondence …

The Dark Side Of Bright Metal Coatings, L. Bartosiewicz, C. J. Kelly

Scanning Microscopy

The surface quality of light reflective metal films on polymer substrates were experimentally examined and evaluated. The study included light optical hotstage microscopy of in-situ samples and scanning electron microscopy. Conditions for producing aluminum metal films with desirable light reflecting properties are relatively demanding. The film formation is a complex series of events which include nucleation, coalescence and crystal growth.

Surface flaws, debris or other imperfections are readily visualized with the aid of the optical or the electron microscope. Although complex methods have been developed for the examination of small surface areas with fine-featured metallic films, there was little incentive …

Endothelial Injury In Human Atherosclerosis, G. Pasquinelli, A. Cavazza, P. Preda, A. Stella, B. I. Cifiello, M. Gargiulo, M. D'Addato, R. Laschi

Scanning Microscopy

A light and electron microscopic investigation (scanning and transmission electron microscopy) was performed on 51 human atherosclerotic carotid lesions. The purpose of this study was to establish whether features of endothelial injury such as those described in animals occur in man and whether these features can be related to specific stages of human atherosclerosis.

Irrespective of their histological appearance the atherosclerotic lesions were covered with endothelium which showed non-specific changes in cell shape and size. However, all complicated lesions appeared denuded. Moreover, a peculiar interaction of endothelium with monocytes and lymphocytes as well as blood components (e.g., fibrin and lipoproteins) …

Secondary Electron Emission: Progress And Prospects, Jørgen Schou

Scanning Microscopy

This article updates the paper "Secondary Electron Emission from Solids by Electron and Proton Bombardment" published in Scanning Microscopy Vol. 2, pages 607-632 (1988). The recent development in secondary electron emission from solids by electron or proton bombardment is reviewed. The similarities between electron- and ion-induced emission are emphasized. Recent theoretical results for the emission from beryllium agree well with existing experimental results. Results from new directions are included in the discussion.