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Environmental Concerns And Natural Resource Scarcity: The Case Of Coal, Soumendra N. Ghosh, Donald L. Snyder

Economic Research Institute Study Papers

An increasing awareness of environmental pollution and its relative impact on mankind have elicited normative and positive economic models that address particular trade-offs between material objects and the maintenance of the environment. The existing literature has primarily been concerned with identifying the optimal amount of socially desirable pollution. However, the issue of natural respurce scarcity, when viewed in conjunction with the availability of environmental resources or related amenities, seems to have attracted only minimal attention thus far. Leading natural resource economists like V. K. Smith (1981), John V. Krutilla and Anthony C. Fisher (1975), and Anthony C. Fisher (1979) have …

Materials Characterization Using The Backscattered Electron Signal In Scanning Electron Microscopy, V. N. E. Robinson

Scanning Microscopy

The backscattered electron signal in scanning electron microscopy is sensitive to changes in the atomic number of the specimen. This atomic number information can be measured by calibrating the output of a backscattered electron detector from two known materials. The atomic number of an unknown sample can then be determined by measuring the backscattered electron signal from the unknown sample.

Knowing the atomic number factor of an unknown sample and the heavy elements (Z > 10 as determined from X-ray analysis), the existence of light elements can be detected. From a knowledge of the sample and valence information, the composition of …

Review Of Fossil Eggs And Their Shell Structure, Karl F. Hirsch, Mary J. Packard

Scanning Microscopy

Of the established eggshell groups (membrane-like, pliable, and rigid), the rigid eggshell group has the best chance of fossilizing. Fossils of this group, with modern-type structure, extend back into the Eocene (crocodiles, gecko) and even into the Cretaceous (birds, turtles).

Structural types which differ from modern types are found as late as the Eocene, and in the Cretaceous they are numerous. These Cretaceous eggshells have, for the most part, been assigned to dinosaurs often without consideration of other egg-laying animals of that time. Only a few eggs and eggshells have been reported from the Jurassic and older periods.

Polarizing and …

Measurement Of Film Thickness On Integrated Circuits Using Energy Dispersive X-Ray Analysis (Edxa), Richard G. Sartore

Scanning Microscopy

The need for a rapid, non-destructive failure analysis of complex integrated circuits has led to the use of energy dispersive x-ray analysis (EDXA), to measure the localized thickness of Si02 and Al films on integrated circuits, by detecting the penetration threshold of the electron beam through the film. The accuracy (10%-20%) is determined by actual Scanning Electron Microscope (SEM) measurements, traceable to a secondary length standard, of the film thicknesses of sectioned samples. In contrast, another SEM based thickness measurement technique, such as Yakowitz-Newbury method, gave results that were 50-100% larger, required higher accelerating voltage that would damage the integrated …

A Metal-Polymer Interface Study Using Electropolymerized Acrylonitrile On Nickel Surfaces, G. Lecayon, P. Viel, C. Le Gressus, C. Boiziau, S. Leroy, J. Perreau, C. Reynaud

Scanning Microscopy

Studies of the interface between mineral and organic materials have been realized for a couple formed between pure transition metal and a polar and polarizable molecule (acrylonitrile).

The results presented show the effects of a local electric field on the activation processes associated with adsorption sites and the molecule, interaction mechanisms and the resulting types of chemical bond.

The structural, electronic and chemical properties of a nickel-polyacrylonitrile interface are described.

Molecular and energetic qualitative models for the interaction mechanisms are proposed.

Matrix Effects In Secondary Ion Mass Spectrometric Analysis Of Biological Tissue, Margaret S. Burns, David M. File, Vaughn Deline, Pierre Galle

Scanning Electron Microscopy

We have made several observations during the course of our studies that show the presence of matrix effects in soft biological tissue and standards. The sputtering rate of gelatin is approximately twice that of epoxy resin, but the ion yield of lithium in gelatin is an order of magnitude less than in epoxy. Osmium impregnation of freeze-dried material significantly alters the localization of calcium, but not potassium and barium. The absolute count rate for calcium in osmicated tissue is increased several-fold above that in freeze-dried tissue. Scanning electron microscopy of sputtered material shows the formation of cones during sputtering, which …

The Enamel Ultrastructure Of Multituberculate Mammals: A Review, D. W. Krause, S. J. Carlson

Scanning Electron Microscopy

The enamel ultrastructure of multituberculate mammals has been sampled extensively and studied intensively and is better known than for any other group of early mammals. The enamel of the earliest multituberculates, those of the Late Triassic-Early Jurassic suborder Haramiyoidea and the Late Jurassic-early Early Cretaceous suborder Plagiaulacoidea, is "preprismatic." With only two exceptions, all Late Cretaceous and early Tertiary genera of multituberculates examined have prismatic enamel. Prisms are either small with circular (complete) boundaries or large with arc-shaped (incomplete) boundaries. There is a remarkably consistent relationship between enamel ultrastructural type and subordinal taxa in that small, circular prisms are usually …

Surveying Battery Cell Sections To Determine The Composition And Spatial Distribution Of Discharge Products Using An Automated Microprobe, B. M. England, M. T. Frost, I. R. Harrowfield, C. M. Macrae, D. A. J. Swinkels, K. E. Turner, C. B. Ward

Scanning Electron Microscopy

Determining the spatial distribution and composition of hydrohetaerolite in polished sections of discharged Leclanché cells requires the measurement of oxygen concentrations on microcrystalline material. This can be done if the composition of the mounting medium is included in the matrix correction of raw intensities. The method of Pouchou and Pichoir (PAP) is used initially to correct raw intensities obtained from surveys of microcrystalline standard material. Mean analyses agree well with the known compositions provided a correction is made for the oxygen content of the mounting medium. The same correction is then applied to the raw data collected when surveying cell …

Characterization Of Clay Fabric Using Critical Point Drying To Preserve Clay Texture And Morphology, B. E. Wawak, W. L. Campbell

Scanning Electron Microscopy

Critical point drying is a sample preparation technique that minimizes damage to some clay fabrics in reservoir rocks. In this technique, the original pore fluids in a sample are replaced successively with acetone, liquid carbon dioxide and air without allowing a high energy meniscus to pass through the sample. Acetone replacement is accomplished in a diffusion dehydration system. SEM micrographs show striking differences between critical point dried clay samples and air dried samples.

Ninety Degree Tilt Module And Double-Sided Stub For Scanning Electron Microscopy, G. L. C. Mcturk

Scanning Electron Microscopy

A simple inexpensive device to achieve ninety degree tilt in some scanning electron microscopes (SEM) not equipped with this facility. A new method of safely mounting and studying both sides of the same fragile flat specimen, without the hazards of remounting; used in conjunction with this device.

A New Surface Analytical Technique With Ion And Laser Beams, Christopher H. Becker

Scanning Electron Microscopy

This paper reviews recent results and developments, while presenting some new information, regarding the development of a novel surface analytical technique that uses nonresonant multiphoton ionization (MPI) of neutral atoms and molecules sputtered by an ion beam, or desorbed by an electron or second laser beam or by thermal means. In this method, called surface analysis by laser ionization (SALI), the nonresonant MPI, or "laser ionization," is coupled with state-of-the-art time-of-flight mass spectrometry to provide extremely sensitive, general, and readily quantifiable surface analysis. A discussion also describes the favorable prospects for implementation of SALI with submicron dimension liquid metal ion …

Quantitative Microanalysis By Time-Of-Flight Laser Probe Mass Spectrometry, J. F. Eloy

Scanning Electron Microscopy

Quantitative multielement microanalyses of insulators and refractory materials are made with an advanced laser microprobe mass spectrometer (LPMS-2S). A plasma in local thermal equilibrium (LTE) is generated in a field-free region in the ion source by a short laser pulse. A magnetic time-of-flight (TOF) mass analyzer is used to optimize ion transmission and mass separation. And, an Eloy-Unsold wide aperture ion detector provides the low noise and wide dynamic range required for accurate analyses. The characteristics of the LPMS-2S are demonstrated with NBS standard reference glasses and are compared with the characteristics of the commercially available LAMMA and LIMA microprobe …

Glow Discharge Effects On Polytetrafluoroethylene Polymers Investigated By Secondary Electron Microscopy And X-Ray Photoelectron Spectroscopy, A. Le Moël, J. P. Duraud, C. Le Gressus, H. Okuzumi

Scanning Electron Microscopy

A glow discharge treatment of Polytetrafluoroethylene avoids charging effects and permits observation of the sample in Scanning Electron Spectroscopy; x-ray Photoelectron Spectroscopy has been used to study changes in the surface chemical composition and electronic structure of the polymer produced by this treatment.

Scanning Electron Microscopy In Bone Pathology: Review Of Methods, Potential And Applications, A. Boyde, E. Maconnachie, S. A. Reid, G. Delling, G. R. Mundy

Scanning Electron Microscopy

This article reviews the applications of SEM methods to human bone pathologies referring to studies made at UCL. We consider the methods which may be most suitable; these prove to be not "routine" in the context of most bio-medical applications of SEM.

Valuable information can be obtained from a bone sample if its edges are ground flat, before making either (a) a matrix surface preparation by washing away all the cells or (b) a mineralising front preparation, by also dissolving the osteoid -for which hydrogen peroxide is recommended to produce a robust specimen. BSE contrast from a cut block surface …

The Role Of Marrow Architecture And Stromal Cells In The Recovery Process Of Aplastic Marrow Of Lethally Irradiated Rats Parabiosed With Healthy Litter Mates, Keiki Hayashi, Koichi Kagawa, Michiyasu Awai, Shozo Irino

Scanning Electron Microscopy

Bone marrow aplasia was induced in rats by whole body lethal irradiation (1,000 rads by x-ray), and rats died of irradiation injury within 7 days.

Correlative studies at light (LM), transmission (TEM) and scanning electron microscopy (SEM) demonstrated swelling of endothelial and reticular cells and hemorrhage due to detachment of sinus endothelial cells on days 1 and 2. With time, structural recovery occurred without hemopoietic recovery. Reticular cells developed small intracytoplasmic lipid droplets on days 3 and 4. This resulted in fatty a plastic marrow within 7 days. On the other hand, in the marrow of irradiated rats parabiosed with …

Influence Of Ion Implantation And Gas Exposure On The Charge In Silicon Oxide Created By Electronic Excitation, J. P. Vigouroux, F. Jollet, J. P. Duraud, C. Le Gressus

Scanning Electron Microscopy

Low energy electron bombardment of amorphous SiO₂ induces point defects such as oxygen vacancy by electronic excitation. The defects build a macroscopic negative charge by trapping of electrons on the localized levels in the band gap; this phenomenon was previously described as the "mirror" effect. In the present paper, we investigate, by mirror effect, the behavior of the charge after an argon, nitrogen and oxygen implantation at 1 and 4 keV, and after exposure to the same gases at various low pressures. We observe a difference of behavior between Ar (or N₂) and O₂, The …

Freeze-Dried Embedded Specimens For Biological Microanalysis, L. Edelmann

Scanning Electron Microscopy

The main problems associated with freeze-drying of biological material for electron microscopy concern the freeze-drying temperatures and times necessary to minimize artifacts. Due to the many parameters involved these problems have to be resolved experimentally. It can be shown that good morphological preservation of chemically unfixed material is possible when freeze-drying is done exclusively in a temperature range between -80°C and -50°C. OsO₄ vapour fixation of the freeze-dried tissue is not necessary and should be avoided because it may cause ion redistribution artifacts. Embedding at low temperature of properly freeze-dried material does not seem to disturb structure and ion …

Dissection Technique For Cochleas Prepared For Scanning Electron Microscopy, Sven Rydmarker, D. E. Dunn, P. Nilsson, C. Lindqvist

Scanning Electron Microscopy

Scanning electron microscopy (SEM) permits a three-dimensional study of the surface morphology of the organ of Corti that is very useful in evaluating the condition of the apical end of the hair cells and the stereocilia. However, some laboratories have experienced problems with curling of the basilar membrane during critical point drying of cochlear specimens prepared For SEM evaluation using the Murakami or osmium thiocarbohydrazide-procedures. This curling of the basilar membrane can obstruct the view of the reticular lamina and the ciliary ends of the hair cells.

We have used a dissection method, referred to as the anchor technique, to …

The Motile Behavior Of Virus-Transformed 3t3 Cells, Guenter Albrecht-Buehler

Scanning Electron Microscopy

Using metallic gold in various assays for the motility of cultured tissue cells, the paper compares the movements of surface projections and the locomotion of polyoma (Py3T3) and SV40 (SV3T3) virus-transformed 3T3 cells with the behavior of the parental 3T3 cells.

The movement of surface projections was assayed by the ability of filopodia, lamellipodia and blebs of freshly plated cells to remove colloidal gold particles from a particle-coated glass substrate. The ability of filopodia to probe the environment for points of anchoraqe was tested by observing cells plated on glass whose filopodia touched the surface of a neighboring area of …

High Sensitivity Ion Microscopy: A Tool For Material Science Research, N. A. Thorne, A. Dubus, F. Degrève

Scanning Electron Microscopy

Direct ion imaging is a strong point of the CAMECA IMS 3f ion microscope, but has undergone little commercial development. A modified image acquisition system is presented which incorporates a high sensitivity video camera allied with a rapid image digitizer/processor. Individual ion impacts on the channel plate are detected at maximum gain and image sensitivity is effectively increased to that of the mass spectrometer. For intermediate (10³ to 10⁵) and low (<10³) count rates image processing such as averaging or integration is essential to improve the poor detection statistics and allow real time image formation. …

The Gill Arch Of The Striped Bass, Morone Saxatilis. Ii. Microvasculature Studied With Vascular Corrosion Casting And Scanning Electron Microscopy, Judy A. C. King, F. E. Hossler

Scanning Electron Microscopy

The gill vasculature of euryhaline striped bass, Morone saxatilis, was examined by scanning electron microscopy of corrosion casts prepared by injecting resin (either Mercox/Sevriton or L.R. White) into the ventral aorta. The vasculature of the striped bass gill appears to be similar to that of other euryhaline species. The striped bass gill has three major vascular systems: (1) a respiratory system, (2) an arterio-venous system, and (3) a nutritive system. In the respiratory system, blood from the afferent branchial artery flows to each filament via an afferent filamental artery, and from there to the highly vascularized respiratory lamellae. Lamellar …

Phase Transitions Of Calcium Oxalate Trihydrate And Epitaxy In The Weddellite-Whewellite System, Sergio Deganello

Scanning Electron Microscopy

The phase changes calcium oxalate trihydrate-weddellite, weddellite-calcium oxalate monohydrate and calcium oxalate trihydrate-whewellite are individually examined at the atomic level from a theoretical point of view; concomitantly the topological requirements necessary for phase stability are clarified for each structure type. In solution a sequential series of phase transitions according to the steps calcium oxalate trihydrate-weddellite-whewellite is not likely to be energetically favoured; direct conversion of calcium oxalate trihydrate to whewellite should be, instead, ordinarily expected.

It is formally demonstrated that along two axial directions a set of atoms is in essentially identical positions in both weddellite and whewellite. This notwithstanding, …

Genes, Manganese, And Zinc In Formation Of Otoconia: Labeling, Recovery, And Maternal Effects, L. C. Erway, N. A. Purichia, E. R. Netzler, M. A. D'Amore, D. Esses, M. Levine

Scanning Electron Microscopy

Published studies indicate that genes and dietary manganese deficiency cause vestibular defects and ataxic behaviors. Manganese deficiency during development causes otoconial defects in mice, rats, guinea pigs, and chicks. Mutant genes cause otoconial defects in mice, mink, and poultry. Manganese supplementation prevents the otoconial defects in some mutant mice and mink. Manganese is essential, before crystallization of the otoconia, for synthesis of mucopolysaccharides and otoconial matrix. Such defects can be induced, after otoconia are crystallized during fetal development, by dietary zinc deficiency and sulfonamide treatment (inhibits carbonic anhydrase, a zinc-requiring enzyme). Manganese and/or zinc supplementation ameliorates otoconial defects in pallid …

Particle Probe Analysis In The Study Of Skin Physiology, Bo Forslind

Scanning Electron Microscopy

The basic function of provide a barrier which the epidermis is will separate the body compartment from the environment thus protecting the organism from excessive loss of water and to hinder the entrance of noxious agents. A continuous renewal of the actual barrier makes it possible to fulfill these requirements. Using particle probe analysis, electron microprobe (EMP) and proton microprobe (PMP) analysis we have demonstrated the feasibility of these techniques in the study of skin physiology. The results reported here have been obtained on quench frozen skin specimens inertly prepared by cryotechniques to produce freeze-dried sections presenting cross sections of …

Integrated Image And X-Ray Microanalysis Of Hepatic Lysosomes In A Patient With Idiopathic Hemosiderosis Before And After Treatment By Phlebotomy, M. I. Cleton, J. M. Roelofs, C. J. G. Blok-Van Hoek, W. C. De Bruijn

Scanning Electron Microscopy

Morphometrical and X-ray elemental information was extracted from Scanning Transmission Electron Microscopy (STEM) images of hepatic lysosomes of a patient with idiopathic hemosiderosis before and after treatment by phlebotomy. The elements of interest were (i) iron, stored in pathological quantities in hepatic lysosomal structures and (ii) cerium, used as a capture ion after a cytochemical reaction to detect acid phosphatase activity in the lysosomal structures.

Morphologically the lysosomal structures are heteromorph and the elements iron and cerium are heterogeneously distributed. With "reduced raster" (= reduced scanning area) analysis at 16 x 16 pixel points (integrating image and X-ray microanalysis), a …

Calcification In Aging Canine Aortic Valve, Kookmin M. Kim, S. H. Chang, B. F. Trump, H. Spurgeon

Scanning Electron Microscopy

Aging changes of aortic valves are thought to underlie the mechanism of calcification, which leads to calcific aortic stenosis in humans. The study of calcification in the aging valvular connective tissue has been hindered by the lack of a suitable animal model. In search of the model, canine aortic valves demonstrated age changes including calcification remarkably similar to those in humans. The mechanism of calcification was studied in the aortic valves of aged Beagles by electron microscopy. Fibroblasts in the canine aortic valves showed the most prominent age changes. The cells accumulated numerous residual bodies and appeared to disintegrate. The …

High Current Density Magnetic Electron Lenses In Modern Electron Microscopes, J. Podbrdský

Scanning Electron Microscopy

New possibilities for the application of high current density magnetic electron lenses in commercially produced electron microscopes are discussed. The optimum current density in the windings of a commercially produced instrument has been determined. An improved indirect water cooling arrangement with a closed, vibration-free, cooling circuit has been found to be a reliable and practical system. This has been made possible by a substantial improvement in the method of manufacturing wire coils, leading to a greatly increased heat transfer. The reduced dimensions of such. coils have made it possible to design a general purpose lens body, that is readily adapted …

A Finite Element Method For The Computation Of Magnetic Electron Lenses, Bohumila Lencová, Michal Lenc

Scanning Electron Microscopy

The success of computer-aided design in electron optics is no longer limited by computing facilities but by our understanding of numerical methods and underlying physical laws used for the computation. This paper deals mainly with the computation of vector potential in rotationally symmetric magnetic lenses. The finite element method, as introduced by Munro in 1971, seems to be the best tool for this purpose, and we aim to show in this paper how it is possible to improve it without losing the original clarity. Therefore we discuss the suitable choice of mesh and the calculation of the coefficients of the …

Optical Microreflectometry And Microscopy Of Chalcopyrite Specimens: Reflectance Calculation And Comparison To Backscattered Electron Microscopy, G. Remond, R. Caye, P. Ruzakowski, P. H. Holloway

Scanning Electron Microscopy

A model was developed to calculate the optical reflectance of an absorbing substrate covered by multiple thin layers of absorbing materials. Both multiple homogeneous thin layers and thin surface layers of mixed phases were modeled. Reflectance versus wavelength was measured for polished chalcopyrite (CuFeS₂) and compared to calculated data. The identity and thickness of surface compounds used to calculate reflectance curves were partially determined using X-ray photoelectron and Auger electron spectroscopies. Very good agreement between theoretical and experimental reflectance curves were observed as a function of surface composition. The hue (color) and luminosity (brightness) of the polished surface …

Ion Optics Of Submicron Ion Beams, H. Liebl, H. Weiss

Scanning Electron Microscopy

An electrostatic objective lens for focusing ion beams to very small diameters on a plane, conducting sample surface was designed. The lens can focus ions of either polarity in the decel-accel or accel-decel mode and collect and collimate secondary charged particles of either polarity emitted with low initial energy. Moreover, a microscopic mirror objective for visual observation of the sample surface in situ is incorporated in the electrostatic optics.