Life Sciences Commons^™

Imaging-Sims (Secondary Ion Mass Spectroscopy) Studies Of Advanced Materials, R. Levi-Setti, J. M. Chabala, J. Li, K. L. Gavrilov, R. Mogilevsky, K. K. Soni

Scanning Microscopy

This article describes the application of scanning ion microprobe (SIM) microanalysis for the characterization of advanced engineered materials. In conjunction with secondary ion mass spectrometry (SIMS), scanning ion microprobes can image elemental distributions over surfaces with high lateral resolution (50-100 nm). With this technique, most elements, including isotopes, can be detected with good sensitivity. The principles and instrumentation associated with the SIM/SIMS technique are briefly described and ongoing developments are outlined. The analytical capabilities of the technique are illustrated by case studies of aluminum-lithium alloys, zinc oxide varistors, aluminum matrix composites, and photographic materials.

Investigation Of Dislocations In Gaas Using Cathodoluminescence In The Scanning Electron Microscope, K. L. Pey, J. C. H. Phang, D. S. H. Chan

Scanning Microscopy

Electrically active dislocations in Si-doped {100} GaAs substrates were observed using the cathodoluminescence (CL) technique in the scanning electron microscope (SEM). CL contrast profiles were experimentally obtained from the dislocations at different beam energies. Based on the CL model for localized defects in semiconductors developed earlier by Pey, the depths of the dislocations were found by locating the beam energy at which maximum CL contrast occurred. A preferential etching technique for {100} GaAs was employed to reveal the dislocations and to measure their depths. The etched depths obtained were compared to the predicted results from the theoretical model developed. The …

Effects Of Ionizing Radiation On The Size Distribution Of Proteoglycan Aggregates Synthesized By Chondrocytes In Agarose, M. Cornelissen, H. Thierens, L. De Ridder

Scanning Microscopy

Effects of ionizing radiation on the structure and size-distribution of newly synthesized proteoglycan aggregates are studied in-vitro. Chondrocytes, isolated from embryonic chick sterna, are cultured for 7 days in a tri-dimensional agarose system. Single radiation doses of 10, 20 and 50 Gy are given before starting the culture. Digestion of the artificial agarose matrix liberates the newly synthesized proteoglycans. Spreading with cytochrome C allows electron microscopic investigations of the individual, newly synthesized molecules.

The structure of aggregates synthesized by control and irradiated chondrocytes is comparable. However, radiation causes alterations in the size-distributions of the aggregate-populations. For the control cultures, an …

Quantitative Elemental Mapping Of Biomedical Specimens Using The Nuclear Microprobe., Jan Pallon, John Knox

Scanning Microscopy

Quantitative and structural elemental information is available from the nuclear microprobe through a time consuming fit of the (X-ray) spectrum at each point. An alternative technique is proposed which greatly shortens the analysis procedure and allows an increased number of samples to be processed. The method discussed here is to create elemental maps which, when they are divided by the charge/pixel and multiplied by a scaling factor, will form quantitative maps. The scaling factors are obtained from a calibration procedure comparing a large number of fitted X-ray spectra with the corresponding contents of selected energy windows. The technique also allows …

Ischemia/Reperfusion Injury Of The Ascending Colon In Ponies: A Correlative Study Utilizing Microvascular Histopathology And Corrosion Casting, B. J. Darien, P. A. Sims, W. C. Stone, D. R. Schilly, R. R. Dubielzig, R. M. Albrecht

Scanning Microscopy

Volvulus of the ascending colon (ACV) in the horse results in microvascular injury and necrosis of the intestinal mucosa. This study investigated the site and type of microvascular injury which occurs within the mucosa and sub mucosa following ACV. Histopathology of volvulus treated ponies demonstrated mucosa! necrosis with microvascular hemorrhage and thrombosis. Thrombi occurred within the subepithelial capillaries and edema and hemorrhage developed throughout the mucosa and submucosa. Vascular casts allowed 3-D viewing of samples obtained from the entire pelvic flexure and demonstrated two distinct microvascular changes: 1) disruption of the colonic glandular capillary network occurred concomitantly with the …

Improved Visualization Of Dna In Aqueous Buffer With The Atomic Force Microscope, Magdalena Bezanilla, Carlos J. Bustamante, Helen G. Hansma

Scanning Microscopy

An improved method has been developed for imaging deoxyribonucleic acid (DNA) in aqueous buffer with the atomic force microscope (AFM). DNA on untreated mica can be imaged in aqueous buffer with the AFM if the DNA is deposited onto the mica in a buffer with HEPES and MgCl₂, if the sample is rinsed thoroughly with high water pressure, and if the imaging is done with an electron beam-deposited (EBD) tip that has been deposited in the scanning electron microscope (SEM). The water rinse removes DNA that is otherwise easily scraped off the substrate. There is evidence that sharper …

X-Ray Microanalysis Of Camp-Induced Ion Transport In Ncl-Sg3 Sweat Gland Cells, Ann-Christin Mörk, Godfried M. Roomans

Scanning Microscopy

cyclic AMP (cAMP)-induced ion transport in a human sweat gland cell line, NCL-SG3, was investigated by X-ray microanalysis. Stimulation with cAMP caused a decrease in cellular Cl and K content in cells grown on impermeable as well as permeable supports. In cells grown on plastic coverslips or Transwell inserts stimulation with cAMP caused a significant decrease of the Na concentration, but no significant effect on the intracellular Na was seen on cells grown on grids. cAMP had no significant effect on the intracellular Ca concentration.

Effects Of Modulated And Continuous Microwave Irradiation On Pyroantimonate Precipitable Calcium Content In Junctional Complex Of Mouse Small Intestine, Z. Somosy, G. Thuróczy, J. Kovács

Scanning Microscopy

The pyroantimonate precipitable calcium content of intestinal epithelial cells was investigated in mice following total body irradiation with 2450 MHz continuous and low frequency (16 Hz) square modulated waves. In the control animals the reaction products appeared in the intercellular space of adjacent cells including intermediate junctions and desmosomes and were absent in the area of tight junctions. Immediately after low frequency modulated microwave irradiation at 0.5 and 1mW/cm² power densities, a rapid distribution of pyroantimonate precipitable calcium content was observed. The pyroantimonate deposits were located on the cytoplasmic side of lateral membrane, in the area of junctional complex, …

Caesium On Si(100) Studied By Biassed Secondary Electron Microscopy, M. Azim, C. J. Harland, T. J. Martin, R. H. Milne, J. A. Venables

Scanning Microscopy

An ultra-high vacuum scanning electron microscope (UHV-SEM) has been used to study sub-monolayers of Cs on Si(100) surface. Cs adsorption on the surface causes a considerable change in the work function. Coverages below 1/2 monolayer (ML) have been estimated by correlating the work function changes with the secondary electron (SE) signal. It has been found that this signal is sensitive down to ~ 0.005 ML when the sample is biassed to a few hundred volts.

Electron trajectories from a biassed sample have been simulated for electrons originating from different areas with different work functions across the sample. This indicates that …

Calcium Phosphate In Aspergillosis Of The Maxillary Sinus, Hidekuni Tanaka, Toshiro Sakae, Hiroyuki Mishima, Hirotsugu Yamamoto

Scanning Microscopy

The unique appearance of apatite in fungus balls of aspergillosis in the maxillary sinus was investigated using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray microdiffraction and Fourier transform infrared spectroscopy (FT-IR). Rod-shaped fragments with tubular structures, and globular vesicles covered with conidia were observed in the fungus balls. Massive fragments of a solid substance were demonstrated inside the fungus balls. Calcium and phosphate were detected in necrotic areas of the fungus balls by EDS. X-ray microdiffraction and FT-IR showed the presence of an apatite-like substance, but failed to demonstrate the presence of calcium oxalate crystals usually found in such …

Optimization And Application Of Jet-Freezing, T. Müller, S. Moser, M. Vogt, C. Daugherty, M. V. Parthasarathy

Scanning Microscopy

Cryofixation is considered to be the best method for immobilizing biological material in its natural state. In jet-freezing, the specimen typically is sandwiched between two carriers and kept in place while a coolant is moved very rapidly against the opposite surfaces. The JFD 030 jet-freezing device has been used to optimize the operating parameters. The course of the temperature in place of a specimen was measured with thermocouples and recorded by an IBM-compatible personal computer using a specifically developed software program. Mean cooling rates, over the temperature range of 273K to 173K, achievable with different cryogens, including the non-flammable HCFC …

Scanning Electron Microscopy Of High-Pressure-Frozen Sea Urchin Embryos, Paul Walther, Ya Chen, Marek Malecki, Sara L. Steffen Zoran, Gerald P. Schatten, James B. Pawley

Scanning Microscopy

High-pressure-freezing permits direct cryo-fixation of sea urchin embryos having a defined developmental state without the formation of large ice crystals. We have investigated preparation protocols for observing high-pressure-frozen and freeze-fractured samples in the scanning electron microscope. High-pressure-freezing was superior to other freezing protocols, because the whole bulk sample was reasonably well frozen and the overall three-dimensional shape of the embryos was well preserved. The samples were either dehydrated by freeze-substitution and critical-point-drying, or imaged in the partially hydrated state, using a cold stage in the SEM. During freeze-substitution the samples were stabilized by fixatives. The disadvantage of this method was …

Micro-Pixe (Particle Induced X-Ray Emission) Analysis Of Aluminum In Rat-Liver Using Mev Heavy Ion Microprobes, Yuji Horino, Yoshiaki Mokuno, Atsushi Kinomura, Kanenaga Fujii, Sakae Yumoto

Scanning Microscopy

Heavy ion microprobes (HIM) such as 3 MeV Si²⁺ and 3 MeV p²⁺ have been applied to the elemental analysis by PIXE (proton-induced X-ray emission). It was found that silicon and phosphorus microprobes have several times higher sensitivity for aluminum Kα X-rays than 2 MeV proton microprobes, and detection limits were more favorable in a phosphorus microprobe. Using a 3 MeV p²⁺ microprobe, the liver of a rat, which had been injected with aluminum-lactate, was investigated and it was found that aluminum segregates in areas with a dimension of about 10 μm. These areas could hardly be …

Intracellular And Extracellular Elemental Composition Of The Endolymphatic Sac Studied By X-Ray Microanalysis, Romuald Wroblewski

Scanning Microscopy

X-ray microanalysis was performed along with light microscopy (LM) on rapidly frozen and cryo-sectioned endolymphatic sac tissues of adult guinea pigs, to determine the elemental composition of the different cell types in this tissue as well as the content of the sac lumen. The morphological preservation and spatial resolution of cryo-sectioned endolymphatic sac was found adequate for the identification of the different cell types of the sac in the transmission electron microscope. Further cell type identification was performed by comparing scanning transmission electron microscopy images with LM images on adjacent serial sections. X-ray microanalysis demonstrated differences between epithelial and sub-epithelial …

Migration Of Epithelium During Phenytoin-Dependent Gingival Overgrowth In Mice, S. H. Ashrafi, B. Atassi, R. Erickson, T. Sabet

Scanning Microscopy

A small cavity was made in the mesiopalatal area of the maxillary first molar adjacent to the gingiva. Mice were maintained on 40 mg/kg phenytoin (or on diluent for control) by daily intraperitoneal injections. After 9 weeks, light microscopic observations revealed that in experimental mice, epithelial cells migrated towards the cavity and covered it. In controls, epithelial cell migration towards the cavity did not occur. For scanning electron microscopic (SEM) studies, specimens were fixed in 4% glutaraldehyde in 0.1 M phosphate buffer, pH 7.2, for 2 hours, dehydrated, critical point dried and coated with gold. The surface of the outer …

Technical Improvements In Corrosion Casting Of Small Specimens: A Study On Mesonephric Tubules And Vessels Of Chicken Embryos, A. Carretero, H. Ditrich, M. Navarro, H. Splechtna, J. Ruberte

Scanning Microscopy

The injection technique for corrosion casting of small, embryonic material can be improved by using a "chemical ligature" (cyanocrylate). With this simple method, leakage of the resin at the injection site is prevented and the mechanical stability of the cannula-vessel coupling is improved.

The blood vascular system of chicken embryos as small as Hamburger-Hamilton stage 24 (approximately 4.5 days of incubation) has successfully been injected using this procedure. Corrosion casts of the mesonephric tubular system have been made in a similar manner. Additionally, a simple way for secure transport of the fragile casts by immersion in 10% gelatin is suggested.

Cross-Sections For Electron Scattering Accompanied By Ionization Of Inner-Shells, M. Kotera, K. Yamamoto, H. Suga

Scanning Microscopy

A method is presented to describe the electron scattering process at an ionization of inner-shell electrons. The differential cross-section with the energy transfer and the momentum transfer is calculated using the expression of the generalized oscillator strength. This cross-section and the total ionization cross-section are fairly close to the results obtained by the Gryzinski equation. The photo-absorption cross-section obtained by the present treatment shows good agreement with the experimental data in a wide range of the photon energy. Based on the present treatment, the scattering angle distribution of the primary electron is calculated.

The Direct Sensing Of Damage To Ion Implanted Materials, J. S. C. Mckee, M. S. Mathur, G. R. Smith

Scanning Microscopy

Material damage caused by the implantation of a high concentration of hydrogenic ions requires regular remote monitoring in order to study the atomic and nuclear reaction processes taking place within each sample. Real time continuous measurements of acoustic emission, X-ray production and emitted particle flux enable processes such as bubble or crack formation, changes in crystalline order, and nuclear fusion reactions can be studied in detail through examination of secondary or associated emission products. Fracturing of a material may generate a unique signature which, when taken in conjunction with time-averaged quantities such as changes in resistivity, surface strain, and induced …

Atomic Force Microscopy Study Of Human Tooth Enamel Surfaces, Ph. Schaad, E. Paris, F. J. G. Cuisinier, J. -C. Voegel

Scanning Microscopy

Human enamel features from individual crystals up to prisms were observed by atomic force microscopy (AFM). Low magnification images of vestibular tooth surfaces show the existence of enamel prisms appearing as deep holes. Individual, parallel enamel crystals show lateral faces elongated and formed by the (100) planes of hydroxyapatite (HA). Height differences between (001) faces create the roughness of enamel surface. Individual (001) crystal faces can be observed clearly at higher magnification and show the characteristic hexagonal shape with 60° angles between (100) faces. This study confirms the applicability of AFM for studying biological hydroxyapatite crystals.

Reduction Of Sunburn Damage To Skin By Topical Application Of Vitamin E Acetate Following Exposure To Ultraviolet B Radiation: Effect Of Delaying Application Or Of Reducing Concentration Of Vitamin E Acetate Applied, John R. Trevithick, David T. Shum, Sahle Redae, Kenneth P. Mitton, Christopher Norley, Stephen J. Karlik, Alan C. Groom, E. E. Schmidt

Scanning Microscopy

The skin of the skh-1 mouse after ultraviolet B (280-320 nm, UVB) irradiation shows the pathological changes typical of sunburn damage: spongiosis (edematous spaces) around some cells, necrosis of keratinocytes, giving rise to sunburn cells, inflammatory infiltration ofpolymorphonuclear leucocytes, etc. In our previous study, these were accompanied by erythema, increased skin sensitivity, and edematous swelling. The topical application of tocopherol acetate (TA) immediately after the UVB exposure decreased these changes. In this paper, multiple measurements of the skin thickness were made at different locations along the magnetic resonance imaging (MRI) cross-sectional image of the skin. This permits effects to be …

Scanning Electron Microscopic Studies Of The Palatine Mucosa And Its Microvascular Architecture In The Rat, S. Sugioka, H. Ike

Scanning Microscopy

Detailed observations were made on the structure and microvasculature of the palatine mucosa of the rat by means of microvascular corrosion casts and epithelium-digested specimens using scanning electron microscopy. The rat palate was divided into four regions according to the characteristics of the palatine plicae. In the atrial region, no transverse palatine plicae were present, but there were longitudinal ridges and folds in the median area. These structures contribute to the transportation of rough and grainy foods with the assistance of the hairy buccal part. Capillary loops in the ridge and folds appeared as continuous, sagittally elongated loops. In the …

Humidity Effects On Atomic Force Microscopy Of Gold-Labeled Dna On Mica, J. Vesenka, S. Manne, G. Yang, C. J. Bustamante, E. Henderson

Scanning Microscopy

Recent work in atomic force microscopy (AFM) of deoxyribonucleic acid (DNA) has relied on immobilizing DNA molecules by drying a small volume of buffered DNA solution onto cleaved mica. When imaging in air, relative humidity has been known to affect both the resolution and measured height of the DNA strands. We present data of measured height versus humidity for DNA and attached gold labels, and we propose a model for this data based on swelling of coadsorbed buffer salts upon exposure to moisture. In this model, small particles (e.g., DNA) stay near the top of the swelling salt layer, whereas …

A Simple Empirical Calibration Of Energy Dispersive X-Ray Analysis (Edxa) On The Cornea, N. F. Schrage, K. Benz, P. Beaujean, W. -G. Burchard, M. Reim

Scanning Microscopy

Monitoring of the corneal electrolyte content is important for the study of chemical eye burns. This paper describes quantitative measurements on gelatin standards, corneas and a cornea homogenate with an energy dispersive X-ray analyzer (EDX) in the scanning electron microscope (SEM). Ten micrometers thick cryosections were freeze-dried and mounted on solid carbon supports. The applied quantification procedure was a local peak background analysis with a specifically designed computer program. Similar chemical and physical properties of gelatin, cornea homogenate, and cornea were proven by EDX-analysis and wet chemical analysis. Gelatin standards with known concentrations of different added salts showed linear correlations …

Mechanisms Of Cavity Growth During Ion Implantation, J. H. Evans

Scanning Microscopy

This paper will review two separate areas of cavity growth under ion implantation, firstly bias-driven void growth occurring in metals over the range 0.3 to 0.5 of the melting point at high displacement doses, and secondly, bubble growth during inert gas implantation. Interesting phenomena take place in both areas, e.g. void swelling and void lattice formation in the first and blistering, bubble lattices and the precipitation of heavier inert gases in the solid phase in the second. These phenomena will be described together with the extension of mechanisms to other implant species such as carbon where the possibility of precipitation …

X-Ray Microanalysis Of Chief Cells In Rat Parathyroid Gland, Romuald Wroblewski

Scanning Microscopy

X-ray microanalysis was used to study the elemental composition of the rat parathyroid gland. Analyses were performed in morphologically defined cells. Use of semi-thin cryosections allowed us to selectively analyze cell nucleus, cytoplasm and occasionally dense granules in the cytoplasm.

The concentration of elements (mmol/kg dry weight) in chief cells of parathyroid gland were as follows: Na 83, Mg 48, P 853, S 224, Cl 164, K 551 and Ca 10. Significantly higher phosphorus and potassium concentrations were found in the dense granules as compared to cytoplasm of the parathyroid chief cells. Choosing rat parathyroid gland gave the possibility to …

Rabbit And Human Non-Keratinising Stratified Squamous Oesophageal Epithelium Displays Similar Microridge Structure By Scanning Electron Microscopy, S. Shasha'a, G. R. Dickson, R. St. C. Gilmore, G. C. Crean, M. M. Butt, K. E. Carr

Scanning Microscopy

Since the oesophageal epithelium of common laboratory animals, rats and mice, is keratinized it is unsuitable for comparison with typical non-keratinized stratified squamous human epithelium. It is thus important to find a suitable animal model for the study of human oesophageal tissue changes. This study investigated the microridge structure of immature and adult rabbit specimens, and adult human biopsies by scanning electron microscopy and morphometry. The investigation revealed a similarity between typical squamous human and adult rabbit oesophageal mucosal epithelium. While human epithelium specimens subdivided into two other groups (non-typical squamous and non-squamous); all typical squamous human biopsies were from …

Local Susceptibility Against Soft Errors In Dynamic Random Access Memories (Drams) Analyzed By Nuclear Microprobes, H. Sayama, M. Takai, H. Kimura, Y. Ohno, S. Satoh

Scanning Microscopy

A novel evaluation technique for soft errors in Mbit DRAMs (dynamic random access memories) has been developed using a 400 keV proton microprobe system. This technique, which is called soft error mapping, consists of a bit-state mapping image and a secondary electron mapping image, and can reveal the correlation between the incident position of protons and susceptibility against soft errors in DRAMs. Soft errors are found to be induced by proton incidence at 400 keV within about 6 μm around the memory cell in the case of DRAMs with a conventional well. The susceptible area against proton incidence is much …

Contributions Of Electron Microscopy To The Study Of The Hypertrophic Scar And Related Lesions, C. Ward Kischer

Scanning Microscopy

Prior to 1969, only one study of the hypertrophic scar had been done using electron microscopy, and that one used electron diffraction. Since that time, studies using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been integral in establishing not only the characteristics of this lesion but in formulating the reasons why the scar develops and how it resolves. The first SEM studies demonstrated a homogeneous, dense dermal matrix which supported the conclusion that the hypertrophic scar and keloid reflected excess collagen. These same studies were integral in identifying the collagen nodule as the basic anatomical unit of …

Observations On The Enamel Of Odontomas, Carla Marchetti, Cesare Piacentini, Paolo Menghini, Marcella Reguzzoni

Scanning Microscopy

The morphological study of odontomas provides an alternative model for observing the formation of dental tissues, since different maturing stages are present simultaneously. Investigations were performed on decalcified samples (using light microscopy and transmission electron microscopy) and on undecalcified samples of complex odontoma enamel (using transmission electron microscopy). Simultaneous presence of prismatic enamel at various maturing stages with different structural characteristics was observed. Such enamel was sometimes associated with layers of ameloblastic cells with characteristics of cells in functional activity. In other sites, the enamel did not present a prismatic structure but it appeared as unstructured material clusters with abundant …

Ascorbic Acid Is An Abettor In Calcium Urolithiasis: An Experimental Study, P. P. Singh, R. Kiran, A. K. Pendse, Reeta Ghosh, S. S. Surana

Scanning Microscopy

Two sets of animal experiments using guinea pigs were planned to evaluate the effect of ascorbic acid supplementation on the lithogenic process. In the first set of experiments, 10, 40, and 60 mg doses of ascorbic acid/100g body weight/day were given for 105 days. Neither of the ascorbic acid doses given induced crystalluria, calcification or stone formation, thereby confirming our previous findings that ascorbic acid in the doses used by clinicians does not cause urolith formation. In the second set of experiments, ascorbic acid was supplemented in hypercalciuric (induced by calcium carbonate feeding) and hyperoxaluric (induced by sodium oxalate feeding) …