Digital Commons Network^™

Scanning Electron Microscopy Of High-Modulus Polyethylene Fibres, N. H. Ladizesky, M. K. M. Pang

Scanning Microscopy

Scanning electron microscopy (SEM) examination of high modulus polyethylene (HMPE) fibres gives rise to a number of artifacts which are here recognized. Antistatic agents may be successfully used for the observation of the woven fibres, but only in conjunction with an intermediate metallic coating. For isolated threads superior results are obtained with the metallic coating alone.

New SEM evidence suggests that the high density of surface cracks produced by plasma treatment of HMPE fibres is associated with an aging process. This can also be activated by mechanical energy or storage at room conditions.

Hereditary Hair Changes Revealed By Analysis Of Single Hair Fibres By Scanning Electron Microscopy, B. Forslind, M. K. Andersson, E. Alsterborg

Scanning Microscopy

In many disorders with a genetic background the sparsity of scalp hairs may deter the clinician from trying to extract information from single hair fibres. Presenting a number of diverse conditions, we propose to show that simple measures can be taken in the doctor's office which makes single fibre analysis a useful tool for assessment of factors involved in genetic disorders including the integument and its appendages. The paper is focussed on the utilization of the scanning electron microscope with the goal of demonstrating that pertinent information can be gained where information from transmission electron microscopy and other techniques are …

Three Dimensional Intracellular Structure Of The Cochlea Using The A-O-D-O Method, A. Nagasawa, R. V. Harrison, R. J. Mount, Y. Harada

Scanning Microscopy

We have observed the three-dimensional intracellular structure of the organ of Corti and the spiral ganglion of the chinchilla using the aldehyde osmium-DMSO-osmium (A-O-D-O) method, and compared our findings with previous studies in the guinea pig. In cells of the spiral ganglion and the organ of Corti, microtubules and other cytoplasmic filaments were digested by OsO₄ during processing to provide a clear view of membranous structures such as mitochondria, endoplasmic reticulum and Golgi apparatus. The appropriate digestion time with 0.1% OsO₄ solution was found to be 60-80 hrs for the organ of Corti and 70-90 hrs for the …

Morphological Correlates Of Mechanotransduction In Acousticolateral Hair Cells, J. O. Pickles, G. W. Rouse, M. Von Perger

Scanning Microscopy

The development of ideas on mechanotransduction in acousticolateral hair cells is described, leading to the current idea that transduction depends on deflection of the bundle of stereocilia by a force parallel to the plane of the sensory epithelium. Electrophysiological experiments are summarised, suggesting that transduction depends on a shear between the different rows of stereocilia, and that the transducer channels are situated towards the tips of the stereocilia. Analysis of the ways that shear between the rows of stereocilia could be detected suggests that tip links are the structures which are most likely to transmit the stimulus-induced forces to the …

Scanning Electron Microscopy To Establish The Marble Weathering Mechanism In The Alhambra Of Granada (Spain), M. A. Bello, L. Martín, A. Martín

Scanning Microscopy

The weathering processes of the white marble from Macael quarries (Almeria, Spain) used in the Alhambra of Granada have been studied with the aim of establishing the weathering factors and mechanism. Unaltered quarry samples have been submitted to diverse accelerated weathering experiments and their morphology compared to the altered materials from the monument. The weathering process stages have been established and the degree of weathering in some monumental dependencies evaluated.

Proton Induced X-Ray Emission Analysis Of Biological Specimens - Past And Future, B. Forslind, K. G. Malmqvist, J. Pallon

Scanning Microscopy

Proton induced X-ray emission (PIXE) analysis is a comparatively new member of the family of spectrographic methods. In the last decade PIXE techniques have been applied to biological problems with great success. This review gives a condensed presentation of recent developments in biological (medical, zoological, and botanical) applications of PIXE analysis with special focus on factors which commonly influence the results, such as calibration, contamination, and preparation. The great advantage of PIXE analysis in studying physiologically important trace elements such as Zn, Mg, Fe, and Cu is underlined. Elemental mapping not only allows quantitative elemental analysis, but can also demonstrate …

Effects Of Modulated And Continuous Microwave Irradiation On The Morphology And Cell Surface Negative Charge Of 3t3 Fibroblasts, Z. Somosy, G. Thuróczy, T. Kubasova, J. Kovács, L. D. Szabó

Scanning Microscopy

Mouse embryo 3T3 cells were irradiated with 2450 MHz continuous and low frequency (16 Hz) square modulated waves of absorbed energy ranging from 0.0024 to 2.4 mW/g. The low frequency modulated microwave irradiation yielded more morphological cell changes than did the continuous microwave fields of the same intensity. The amount of free negative charges (cationized ferritin binding) on cell surfaces decreased following irradiation by modulated waves but remained unchanged under the effect of a continuous field of the same dose. Modulated waves of 0.024 mW/g dose increased the ruffling activity of the cells, and caused ultrastructural alteration in the cytoplasm. …

The Measurement Of Aluminum Surface Diffusion On Si, Sio2, And Si3n4 By Scanning Auger Microscopy, L. L. Levenson, A. B. Swartzlander, A. Yahashi, H. Usui, I. Yamada

Scanning Microscopy

The diffusion distance of Al atoms on Si(111), SiO₂, and Si₃N₄ substrates has been measured as a function of substrate temperature. These studies were carried out by depositing Al from an effusive source and from an ionized cluster beam source. Both sources were used in the same apparatus at different times. The deposition was carried out with either a slit mask or a wire mask at the substrate. After the masks were removed, the deposit was examined by optical and electron microscopy, mechanical profilometer, and Auger line scans. The diffusion distance of Al on the …

Enhancing The Laser Scanning Confocal Microscopic Visualization Of Lucifer Yellow Filled Cells In Whole-Mounted Tissue, David L. Becker, Joanna Dekkers, Roberto Navarrete, Colin R. Green, Jeremy E. Cook

Scanning Microscopy

The laser scanning confocal microscope (LSCM) is an extremely useful tool that allows fluorescently labelled cells to be visualized in whole-mount preparations. This is particularly advantageous, for example, in studying the dendritic trees of neurons with respect to their environment.

One of the most popular, and easiest, ways to visualize a cell is to inject it intracellularly with the fluorophore Lucifer Yellow (LY). However, the argon gas lasers of most LSCM's are not well matched to the excitation spectrum of aqueous LY. When this largely inappropriate excitation is combined with standard filters, designed for fluorescein fluorescence rather than Lucifer Yellow, …

Initial Climate Change Scenario For The Western United States, United States Department Of The Interior, Bureau Of Reclamation

Meterology

Observations of atmospheric carbon dioxide (CO₂) concentrations in recent decades have shown an accelerating upward trend due mainly to burning of fossil fuels. Physical considerations indicate that observed and projected increases in the concentrations of CO₂ and other greenhouse gases in the atmosphere will lead to significant global warming. Previous authors have followed both empirical and theoretical approaches to develop scenarios for changed climate conditions. The most common empirical approach is the use of analogs of global warming drawn from historical records and paleoclimates. The principal theoretical approach involves the interpretation of output for general circulation models …

Sheep Production In 11 Western States, United States Department Of Agriculture, Economic Research Service

Agriculture

Net cash returns of U.S. sheep producers were positive for the past 18 years, yet the industry in 1986 experienced the largest declines in number of sheep farms and in sheep population since 1942. Per capita consumption of lamb and mutton has trended downward since 1962, remaining below 1.5 pounds for the past 13 years. The 1986 USDA Farm Costs and Returns Survey indicates that the major sheep production practices of shed and range lambing have not changed significantly since 1980, and losses from disease and predators are high. Sheep production requires more hired labor and operator time than any …

The Vascularization Of The Digestive Tract Studied By Scanning Electron Microscopy With Special Emphasis On The Teeth, Esophagus, Stomach, Small And Large Intestine, Pancreas, And Liver, S. Aharinejad, A. Lametschwandtner, P. Franz, W. Firbas

Scanning Microscopy

The periodontal vessels in adult rats show a ladder-like pattern; in guinea pigs molars, by contrast, they present a honey-comb pattern. The vascular architecture in human teeth seems to be similar to that of rabbits. In guinea pigs, rats, rabbits and humans esophagus circumferential vessels give off perforating vessels. In human esophagus the number and diameter of the vessels in the submucous venous plexus decrease from proximal to distal. In the stomach the subepithelial capillary network shows a honey-comb pattern reflecting the arrangement of the gastric pits. A local portal system between the gastric glands and the surface mucosal cells …

Preparation And Characterization Of Some Particulate Materials In The Aluminum Industry, A. Csordás-Tóth, B. Szikora, J. Kürthy-Komlósy, I. Tassy

Scanning Microscopy

Preparation and characterization techniques for the following particulate materials are reviewed: micromineralogical samples of bauxite, alumina and its trihydroxide, as well as sedimentary and respirable particles. Scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDS) and image analysis were used to characterize the microminerals of bauxite. Comparisons were made among micromineralogical samples with various grain size fractions and the degree of weathering could be quantified. Programs were developed for characterization of the sandy and floury types of aluminum trihydroxide and alumina. We have used backscattered electron SEM images to characterize the size and shape of various aluminum trihydroxides. Comparison could …

Comet: Gateway To Commercial Space, Thomas Ajluni, James Hager

Small Satellite Conference

The COMmercial Experiment Transporter (COMET), scheduled to begin its first mission in September of 1992, is expected to be the baseline that is used to measure the capabilities of the next generation of commercial "To Space and Back" systems. This paper provides an overview of the COMET system with emphasis on its operational capabilities. The design of the Service Module (spacecraft bus) will be highlighted and its modular design and flexible architecture will be discussed.

A Global Enviromental Data Distribution System, Philip Walker

Small Satellite Conference

This paper describes a global environmental data distribution system (GEDDS) which uses a single small satellite operating in a low polar orbit. The satellite collects environmental data from remotely located instrumentation platforms and distributes it to research laboratories and other interested organizations virtually anywhere in the world. A command link also allows principal investigators to control and calibrate platform instruments on a daily basis directly from their laboratory or office.

Medsat: A Small Satellite For Malaria Early Warning And Control, James Slawski, John Vesecky, Byron Wood, James Lawless

Small Satellite Conference

This paper presents the design for a low cost, light satellite used to aid in the control of vector-borne diseases like malaria. The 340 kg satellite contains both a synthetic aperture radar and a visual/infrared multispectral scanner for remotely sensing the region of interest. Most of the design incorporates well established technology, but innovative features include the Pegasus launch vehicle, low mass and volume SAR and VIS/IR sensors, integrated design, low power SAR operation, microprocessor power system control, and advanced data compression and storage. This paper describes the main design considerations of the project which include, the remote sensing task, …

Heterogeneity Of Crystals Attached To The Human Enamel And Cementum Surfaces After Calculus Removal In Vitro, T. Kodaka, K. Debari, M. Yamada

Scanning Microscopy

Twenty one extracted human teeth with dental calculi on the enamel and cementum surfaces, fixed in 10% neutral formaldehyde, were selected for this study. After ethanol dehydration and air drying, these calculi were removed by tweezers to observe the teeth surfaces under them. The inspection of these surfaces using SEM and EDX revealed hexahedrally based crystals including pseudocuboidal, rhombohedral and variable rugged rocky shapes. These crystals were identified as Mg-containing whitlockite. The pseudocuboidal crystals, measuring about 4.5 μmin maximum length, were widely distributed on the cervical enamel surface previously covered by calculus. On the root surface, however, these areas decreased …

Elemental Analysis And Fine Structure Of Mitochondrial Granules In Growth Plate Chondrocytes Studied By Electron Energy Loss Spectroscopy And Energy Dispersive X-Ray Microanalysis, Joanna Wroblewski, Romuald Wróblewski, Claudie Mory, Christian Colliex

Scanning Microscopy

Electron energy loss spectrometry - EELS, and energy dispersive X-ray microanalysis - XRMA, were used to study the elemental composition of mitochondrial dense granules - mdg. The study was performed on dry cut thin sections (80-200 nm) of freeze-dried and low temperature embedded cartilage. Results obtained by means of XRMA clearly showed high phosphorus and calcium content in the mdg. Using EELS at 100 kV primary voltage we found that small concentrations of elements (i.e. below typically 1% atomic weight) are difficult to analyze and map, this especially in sections thicker than 50-60 nm. Surprisingly, analysis of calcium can be …

In Vitro And In Vivo Replication For Scanning Electron Microscopy Of The Cervical Region Of Human Teeth, Joan Bevenius, Kjell Hultenby

Scanning Microscopy

A replica technique for scanning electron microscopy (SEM) of the cervical region of human teeth was evaluated on extracted premolar teeth by comparing the replicas and the original specimens in the SEM. For in vivo application, the technique was modified to circumvent contamination by saliva and gingival exudate. Impressions were taken with an addition silicone polyvinylsiloxane material and the replicas were poured in epoxy resin die material. A surface active dentine conditioner facilitated flow of the impression material into irregular surface areas; in vivo a scavenger impression was used to remove surface debris. Custom trays were made of light-cured acrylic …

Seed Coat Structure In Some Species Of Trigonella, Mohini Gupta

Scanning Microscopy

Seed coats of nine species of Trigonella, members of Trifolieae, were studied using light and scanning electron microscopy to assess seed coat characters taxonomically. In all species, the testa is of the papillose type except T. geminiflora in which it is of the multi-reticulate type. Based on some of the seed characters such as their shape, size, surface, position of hilum and the features of papillae, a key has been developed to identify different species of this genus. Further, in a highly evolved group like section Bucerates, it has been found that the surface is either papillose without …

Digitized Cathodoluminescence Imaging Of Minerals, Ian M. Steele

Scanning Microscopy

Digital imaging with cathodoluminescence (CL) capability, provides an additional, quantitative imaging perspective. While CL images can be useful by themselves, most microbeam instruments allow simultaneous acquisition of other signals including backscattered electron (BSE), secondary electron (SE), and X-ray images providing a powerful set of data for interpretation. Digital panchromatic images allow the use of standard and advanced image processing now available on laboratory computers to enhance single images or provide a means of combining information from two or more images. Other advantages of digital CL images include: 1) selective scan rates to avoid image distortion; 2) adjustable dwell times at …

Influence Of Ageing, Ph And Various Additives On Crystal Formation In Artificial Urine, A. L. Rodgers, M. A. E. Wandt

Scanning Microscopy

In order to investigate the effect of various factors on urinary crystallization processes, a series of five experiments was carried out using an artificial urine (AU) in a rotary evaporator. The influence of ageing, pH and organic, inorganic and potential inhibitory additives formed the basis of the study. Precipitates were characterized by X-ray powder diffraction, scanning electron microscopy and energy dispersive X-ray analysis. In the ageing experiment, AU aliquots, adjusted to various pH values, were allowed to stand for several days and were not evaporated. Calcium oxalate monohydrate (COM) was formed at low pH, while whitlockite, apatite and struvite occurred …

High-Resolution, Real-Space Imaging Of Conformational Structures Of Poly-L-Proline Helixes, N. J. Zheng, G. Rau, C. F. Hazlewood, C. Rau

Scanning Microscopy

In 1954, Edsall postulated that the imino-acid proline, which is a frequently found constituent of protein molecules, is a key determinant to the three-dimensional architecture of proteins. It not only should play a fundamental role in stabilizing helical structures of polypeptides, it should allow for sharp bends and even for a complete reversal of the direction of a helix looping back on itself. No direct evidence has yet been published to prove this prediction. Using scanning tunneling microscopy, we have presented high-resolution, real-space images of two conformations of poly-L-proline, where one structure clearly exhibits the predicted 180° back-folding behavior. The …

Localisation Of Putative Mechanoelectrical Transducer Channels In Cochlear Hair Cells By Immunoelectron Microscopy, Carole M. Hackney, David N. Furness, Dale J. Benos

Scanning Microscopy

Displacement of the apical stereociliary bundle of cochlear hair cells mechanically gates transducer channels. Knowing the position of the channels with regard to the apical structures of the hair cell could indicate how this mechanism operates. At present, there is conflicting evidence regarding their precise location; the channels have been suggested to be located either towards the base of the stereocilia or at the tips where they could be operated by extracellular links running from the top of shorter stereocilia to the sides of adjacent taller ones. The channels have been shown to be reversibly blocked by amiloride. This has …

Terminal Differentiation Of Human Fibroblasts Is Induced By Radiation, H. Peter Rodemann, Hans-Peter Peterson, Karla Schwenke, K. -Hartmut Von Wangenheim

Scanning Microscopy

In order to analyze the effect of various kinds of radiation on the terminal differentiation processes of fibroblasts in culture, both human skin and lung fibroblasts were irradiated with electromagnetic non ionizing as well as ionizing radiation in clonal and sparse mass culture systems. As analyzed by cell biological (cell type frequencies), biochemical (collagen synthesis) and molecular markers (expression of protein PIVa) human skin and lung fibroblasts are induced to differentiate prematurely into terminal postmitotic cells. Thus, both electromagnetic and ionizing radiation induce terminal differentiation in cultured cells. These data add some new aspects for the interpretation of radiation effects …

Effect Of A Platinum Chemotherapy Drug On Intracellular Elements During The Cell Cycle, Using X-Ray Microanalysis, P. G. Edwards, M. D. Kendall, I. W. Morris

Scanning Microscopy

Intracellular elemental concentrations were measured in the cytoplasm, nucleus and nucleolus of cultured Chinese hamster ovary (CHO) cells, using energy dispersive electron probe X-ray microanalysis and transmission electron microscopy. Synchronous CHO cell populations were analyzed at different times during the growth cycle. The elements K, P, Mg and Zn were all more concentrated in the nucleus and nucleolus than in the cytoplasm, while no specific subcellular compartmentalization was evident for the elements Na, Cl, Ca, Fe and S. Significant changes in intracellular elemental concentrations were associated with the progression of cells from G₁ phase to S phase of the …

Band Positions Used For On-Line Crystallographic Orientation Determination From Electron Back Scattering Patterns, N. H. Schmidt, J. B. Bilde-Sørensen, D. Juul Jensen

Scanning Microscopy

A computer procedure for on-line analysis of electron back scattering patterns (EBSP) has been developed. An experimental EBSP is computer recorded and displayed on a computer monitor. The user identifies the positions of at least two bands in the EBSP with a cursor. Based on this input the computer calculates possible crystallographic orientations. The corresponding EBSPs are simulated and superimposed on the experimental EBSP. The correct crystallographic orientation is determined from a comparison between the experimental and simulated EBSPs. Typically, the analysis takes a 10-30 seconds per pattern. Advantages with the present procedure are that it can be applied for …

Low Voltage Scanning Electron Microscopy Cathodoluminescence Observations Of Gallium Arsenide, S. Myhajlenko

Scanning Microscopy

A series of low voltage ( < 5 keV) and low temperature ( < 20K) cathodoluminescence (CL) measurements were performed on epitaxial gallium arsenide. The purpose of these measurements was to ascertain which factors were important in furthering the development of low voltage scanning electron microscopy (LVSEM) CL. LVSEM CL potentially offers great improvement in spatial resolution and the ability to probe the optical properties of surface states. Anomalous CL effects resulting from contamination at beam voltages below 3.5 keV have been interpreted in terms of cross-over potential phenomena. Luminescence dead layers were reduced to near zero in this regime. Excitonic processes were found to be particularly sensitive to injection level and surface conditions. Very weak free-to-bound transitions persisted down to 200 eV beam voltage.

Comparing Simulated And Experimental Hysteretic Two-Phase Transient Fluid Flow Phenomena, R. J. Lenhard, J. C. Parker, Jagath J. Kaluarachchi

Civil and Environmental Engineering Faculty Publications

A hysteretic model for two-phase permeability (k)-saturation (S)-pressure (P) relations is outlined that accounts for effects of nonwetting fluid entrapment. The model can be employed in unsaturated fluid flow computer codes to predict temporal and spatial fluid distributions. Consideration is given to hysteresis in S-P relations caused by contact angle, irregular pore geometry, and nonwetting fluid entrapment effects and to hysteresis in k-Srelations caused by nonwetting fluid entrapment effects. An air-water flow experiment is conducted with a 72-cm vertical soil column where the water table is fluctuated to generate scanning S-P paths. Water contents are measured via a gamma radiation …

The Role Of Tamm-Horsfall Glycoprotein And Nephrocalcin In Calcium Oxalate Monohydrate Crystallization Processes, B. Hess

Scanning Microscopy

Theoretical considerations as well as clinical observations suggest that the aggregation of nucleated crystals is the most dangerous step in the formation of calcium oxalate (CaOx) renal stones. The effects of 2 major urinary glycoproteins, Tamm-Horsfall glycoprotein (THP) and Nephrocalcin (NC), on calcium oxalate monohydrate (COM) crystal aggregation in vitro are studied. At low ionic strength (IS) and high pH (within urinary limits), THP is a powerful crystal aggregation inhibitor (90% inhibition at 40 mg/l). Decreasing pH to 5.7 and raising IS to 0.21 increases THP viscosity, thereby lowering THP crystal aggregation inhibition. Upon addition of calcium …