bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation of three Dimensional Defect Images in Transmission Electron Microscopy
Authors: Cooper W. D. , Hartley C. S. , Hren J. J.
Published: June 2020

Interpretation of electron microscope images of crystalline lattice defects can be greatly aided by computer simulation of theoretical contrast from continuum models of such defects in thin foils. Several computer programs exist at the present time, but none are sufficiently general to permit their use as an aid in the identification of the range of defect types encountered in electron microscopy. This paper presents progress in the development of a more general computer program for this purpose which eliminates a number of restrictions contained in other programs. In particular, the program permits a variety of foil geometries and defect types to be simulated.

The conventional approximation of non-interacting columns is employed for evaluation of the two-beam dynamical scattering equations by a piecewise solution of the Howie-Whelan equations.
Computer Assisted Image Reconstruction of Oligomer Structure
Authors: Jones A.M. , Max Fiskin A.
Published: June 2020

If the tilt of a specimen can be varied either by the strategy of observing identical particles orientated randomly or by use of a eucentric goniometer stage, three dimensional reconstruction procedures are available (l). If the specimens, such as small protein aggregates, lack periodicity, direct space methods compete favorably in ease of implementation with reconstruction by the Fourier (transform) space approach (2). Regardless of method, reconstruction is possible because useful specimen thicknesses are always much less than the depth of field in an electron microscope. Thus electron images record the amount of stain in columns of the object normal to the recording plates. For single particles, practical considerations dictate that the specimen be tilted precisely about a single axis. In so doing a reconstructed image is achieved serially from two-dimensional sections which in turn are generated by a series of back-to-front lines of projection data.
Bright-Field Images (Ctem) of Phase Objects at High Resolution
Authors: Iijima Sumio
Published: June 2020

We have developed a technique to prepare thin single crystal films of graphite for use as supporting films for high resolution electron microscopy. As we showed elsewhere (1), these films are completely noiseless and therefore can be used in the observation of phase objects by CTEM, such as single atoms or molecules as a means for overcoming the difficulties because of the background noise which appears with amorphous carbon supporting films, even though they are prepared so as to be less than 20Å thick. Since the graphite films are thinned by reaction with WO3 crystals under electron beam irradiation in the microscope, some small crystallites of WC or WC2 are inevitably left on the films as by-products. These particles are usually found to be over 10-20Å diameter but very fine particles are also formed on the film and these can serve as good test objects for studying the image formation of phase objects.
Optical Microdiffraction in Lattice Image Analysis
Authors: Gronsky R. , Sinclair R. , Thomas G.
Published: June 2020

Our applications of lattice imaging to the study of phase transformations in alloys have recently incorporated laser optical techniques to improve microdiffraction capabilities by three orders of magnitude over that attainable in conventional transmission electron microscopy (1). The method is based on optical diffraction from lattice image negatives which have been taken under optimum conditions dictated by computed image simulation. In this paper we present the optical microdiffraction data of two experiments to illustrate the role of this technique in metallurgical analysis.

1)Recent observations (2) in Mg3 Cd have revealed the occurrence in thin foils of a structural transition: hexagonal DO19 →orthorhombic B19. In orientations where the Mg3Cd basal plane is parallel to the foil surface, selected area diffraction (S.A.D.) analysis fails to distinguish these phases.
Low-Loss Images in a Stem/Tem Microscope
Authors: Joy David C. , Maher Dennis M.
Published: June 2020

High-resolution images of the surface topography of solid specimens can be obtained using the low-loss technique of Wells. If the specimen is placed inside a lens of the condenser/objective type, then it has been shown that the lens itself can be used to collect and filter the low-loss electrons. Since the probeforming lenses in TEM instruments fitted with scanning attachments are of this type, low-loss imaging should be possible.

High-resolution, low-loss images have been obtained in a JEOL JEM 100B fitted with a scanning attachment and a thermal, fieldemission gun. No modifications were made to the instrument, but a wedge-shaped, specimen holder was made to fit the side-entry, goniometer stage. Thus the specimen is oriented initially at a glancing angle of about 30° to the beam direction. The instrument is set up in the conventional manner for STEM operation with all the lenses, including the projector, excited.
Observation of Atom Images by Means of Field Emission Stem
Authors: Todokoro H. , Nomura S. , Komoda T.
Published: June 2020

A number of studies of single atom image observation utilizing either scanning transmission electron microscope ( STEM ) or conventional electron microscope ( OEM ) have been reported. For this purpose, the dark field image observation seems more promising because the scattering cross-section of an atom is extremely small. Much attention has been paid to decreasing background noises resulting from the supporting film. A thin amorphous carbon film is often utilized as a supporting film. However, many high contrast spots appear even in the dark field image when OEM is used. Matsuda and Nagata3 applied an incoherent illumination technique to the bright field image observation of OEM, and succeeded, in removing the phase contrast effects from the image.
Evaporative Cooling of High Current Density Mini-Lenses
Authors: Parker N. W. , Utlaut M. , Crewe A. V.
Published: June 2020

Mulvey has described microscope lenses which are considerably smaller than conventional lenses due to the higher current densities which he can achieve by using a more efficient cooling system. There are some difficulties associated with this type of lens, however, which make it potentially difficult to use in high resolution microscopes. First of all, the velocity of water flow is necessarily high in order to provide the cooling required (0.5 Watts/cm2) , making the Reynolds number high and turbulence inevitable. Such turbulence produces vibration. Secondly, the temperature rise is high so that one cannot easily avoid increasing the temperature of the column which can lead to outgassing and subsequent specimen contamination.
Optimum Detector Arrangements in the Stem for Thick Objects
Authors: Rose H. , Fertig J.
Published: June 2020

Radiation damage is the main obstacle in achieving high resolution images of biological objects. Therefore it is desirable to indicate that imaging method which yields maximum information about a specific object for a given number N0 of incident electrons. The amount of useful information is determined by the signal to noise ratio. Applying difference techniques the contrast in the STEM can be varied arbitrarily (l). Although the subjective impression of the image quality may be improved by such a procedure the amount of information available will not be changed. Most of the present day STEMs operate in the dark field mode using an annular detector which collects all electrons scattered out of the illumination cone. The corresponding incoherent bright field image is obtained from the electrons which pass through the hole of the dark field detector.
The Use of Tilted Beam Bright-Field Illumination in High Resolution Electron Microscopy
Authors: Krakow William
Published: June 2020

Once it is understood in terms of wave optical transfer theory, tilted beam bright-field illumination can be applied to a variety of high resolution microscope problems which encompass lattice imaging and imaging nonperiodic objects. The tilted beam method offers the advantages of increasing the resolution and allowing both elastically and inelastically scattered electrons to contribute to high spatial frequency detail in a micrograph. In the simplest case, one can demonstrate these effects by the conventional lattice imaging mode using a single diffracted beam and the direct transmitted beam positioned symmetrically on either side of the microscope optic axis. However, the transfer theory of the microscope for tilted beam illumination shows that the cancellation of chromatic aberration occurs not only for the one diffraction direction across the optic axis from the unscattered beam, but also for an entire circle centered about the axis in the back focal plane (BFP) of the microscope.
Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C
Authors: Hall Ernest L. , Vander Sande J. B.
Published: June 2020

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.
Linear Defects Generated by Inclusion of Hydrogen in Nickel Electrodeposit
Authors: Nakahara S.
Published: June 2020

During the course of structural characterization of nickel electrodeposit, we have found that there are a large number of linear defects which are different from dislocations. This communication reports a detailed analysis of these defects using transmission electron microscopy.

Nickel film was prepared by electrodeposition from a bath containing 0.43 M NiSO4-6H2O and 0.5 M H3BO3. The pH of the bath was adjusted to 1.5. A sheet of annealed OFHC copper was used as the substrate. All the platings were carried out at 30°C.

Nickel film plated at a current density of 5 MA/cm2 contained these linear Refects. Figures l(a), (b), and (c) show micrographs of the film taken with g = 200, 220, and 131, respectively. The images of the defects are indicated by four fine arrows in Fig. 1(c). They were not easily discernible with low-order g's such as 111, 200, and 220 (see Figs. 1(a) and (b)).
Dental Plaque Morphology and Induction
Authors: Dockum Norman L. , Schiess Alvin V.
Published: June 2020

Investigators consider plaque to be an early stage of calculus. The plaque matrix may contain a modified protein on which the calculus crystals may form. Another view is that lowering of the pH to 5 or 6 may cause a protein to precipitate on which the calcium crystals deposit. Others are of the opinion that some bacteria may produce a polysaccharide that forms the sticky bulk of the plaque which favors adhesion of bacteria together with acid formation which initiates the formation of calculi. In bone mineralizatipn the crystals are first found to be approximately 300-1500A in length and about 15-75A thick. These grow larger as calcification proceeds.
Fine Structural Evaluation of Bone Cells in Thyroparathyroidectomized Rats Receiving Vitamin
Authors: Weisbrode S. E. , Capen C. C.
Published: June 2020

Although small amounts of vitamin D are necessary for the hypercalcemic effects of parathyroid hormone, vitamin D in sufficient amounts can induce bone resorption in parathyroidectornized animals. The objective of this investigation was to evaluate the response of bone in mature thyroparathyroidectomized (TXPTX) rats to feeding low calcium diets containing no vitamin D (group 1), normal (group 2) and pharmacologic doses (group 3) of vitamin D for 7 days. These findings were correlated with changes in serum calcium (Ca) and phosphorus (P), urinary hydroxyprol ine:creatinine (HOP:CR) excretion, and bone calcium-dependent adenosinetriphosphatase (Ca-ATPase) quantitation and ultrastructural localization.

Pharmacologic doses of vitamin D caused a significant rise in serum Ca (10.22 ± 0.33 mg/100 ml) and urinary HOP:CR (0.31 ± 0.02) and a fall in serum P (12.14 ± 0.65 mg/100 ml) compared to rats in group 1.
Ultrastructural Studies of the Action of Australian Spider Venoms
Authors: Hamilton Ross C.
Published: June 2020

Ultrastructural studies have shown that Black Widow Spider venom has dramatic effects on motor nerve terminals causing in amphibians and mammals the disappearance of synaptic vesicles and in mammals the degeneration of nerve endings. There are two deadly Australian Spiders, the Red Back (Latrodectus mactans hasseltii), a subspecies of the Black Widow (Latrodectus mactans), and the Funnel Web Spider (Atrax robustus), unrelated. Because the Black Widow and Red Back are closely related it was anticipated that their venoms would have similar actions. Pharmacological studies indicated that the Funnel Web Spider venom also acted by releasing acetylcholine. The action of these venoms on nerve endings was studied.
Control of Autogenous Vein Grafts Prior to Reimplantation, By Electron Microscopy
Authors: Watson John H. L. , Swedo John L. , Vrandecic M.
Published: June 2020

The ambient temperature and the nature of the storage fluids may well have significant effects upon the post-implantation behavior of venus autografts. A first step in the investigation of such effects is reported here. Experimental conditions have been set which approximate actual operating room procedures. Saphenous veins from dogs have been used as models in the experiments. After removal from the dogs the veins were kept for two hours under four different experimental conditions, viz at either 4°C or 23°C in either physiological saline or whole canine arterial blood. At the end of the two hours they were prepared for light and electron microscopy. Since no obvious changes or damage could be seen in the veins by light microscopy, even with the advantage of tissue specific stains, it was essential that the control of parameters for successful grafts be set by electron microscopy.
The Current Situation in Chemical Stabilization of Biological Materials
Authors: Luft John H.
Published: June 2020

With information processing devices such as radio telescopes, microscopes or hi-fi systems, the quality of the output often is limited by distortion or noise introduced at the input stage of the device. This analogy can be extended usefully to specimen preparation for the electron microscope; fixation, which initiates the processing sequence, is the single most important step and, unfortunately, is the least well understood. Although there is an abundance of fixation mixtures recommended in the light microscopy literature, osmium tetroxide and glutaraldehyde are favored for electron microscopy. These fixatives react vigorously with proteins at the molecular level. There is clear evidence for the cross-linking of proteins both by osmium tetroxide and glutaraldehyde and cross-linking may be a necessary if not sufficient condition to define fixatives as a class.
Stabilization of Unfixed Tissue with Glycol for the Cytochemical Demonstration of Labile Enzymes
Authors: Slezák Ján , Pease Daniel C.
Published: June 2020

Ultrastructure generally suffers severely whenever fresh tissue has to be used for cytochemical localizations. Experience with "inert dehydration" with glycol as developed by Pease, indicated that significant morphological stabilization could be achieved without fixation even though considerable water remained in the system. Presumably, also, enzymatic denaturation might be avoided. Therefore, we have tried to explore these advantages in a series of pilot experiments.

Succinic dehydrogenase is a chemically labile enzyme which can be demonstrated by a Cu-ferricyanide reaction developed by Kerpel-Fronius and Hajos. Its enzymatic activity proved to be compatible with substantial amounts of glycol. The best compromise between reactivity and the preservation of fine structure was obtained with the following protocol, beginning with placing fresh slabs of rat heart muscle into the standard incubation medium to which 10% glycol had been added.
In vivo Acid Phosphatase Activity of Entamoeba histolytica
Authors: Lushbaugh W. B. , Pence D. B. , Deas J. E. , Miller J. H.
Published: June 2020

The histochemical localization of phosphohydrolase activity in Entamoeba histolytica in light microscopic studies has been conflicting and inconclusive. Maegraith et al. suggested that the “digestive mucosa” of E. histolytica might be associated with the secretion of enzymes across the cell membrane for extracellular digestion. Eaton et al. have suggested the presence of a surface active lysosome with a trigger mechanism on the basis of EM studies on amebae in tissue culture. The present study involves the demonstration of acid hydrolases in vivo.

Caecal ulcerations produced in guinea pigs by the inoculation of polyxenically reared amebae (J-22) were excised, glutaraldehyde fixed, embedded in liquid agar, sectioned at 50 micra and incubated for hydrolase activity.
Electron Microscopy of RNA Released from Chikungunya Virus Varions and DNA of Chlamydia Psittaci
Authors: Higashi N. , Matsumoto A. , Nagatomo Y.
Published: June 2020

Electron microscopy of Chikungunya virus RNA: The molecular weight of the nucleic acid of animal RNA viruses such as poliovirus(N. Granboulan and M.Girard, 1969), myxovirus(L. Kwok-Kwong and J.T.Seto, 1971), murine leukemia virus(T. Kakefuda and J.P.Bader, 1969) and mouse mammary tumour virus(N.H. Sarker and D.H.Moore, 1970) has been successfully estimated in the electron microscope, applying the protein monolayer method developped by Kleinschmidt and his coworkers(l964). However, there has been no electron microscope studies on the molecular weight of RNA of arboviruses.

Highly purified preparation of a BaH strain of Chikungunya virus(CHV), a member of group A arbovirus, was obtained from infected VERO cell cultures by the differential centrifugation involving sedimentation through 25% sucrose solution and density gradient centrifugation by the use of potassium tartrate(l7-27%).
A Method for Direct Observation of Botanical Tissues and Intracellular Contents by SEM
Authors: Panessa Barbara J. , Gennaro F.
Published: June 2020

When biological (non-conducting) specimens are examined in the scanning electron microscope (SEM), local accumulations of electrons (charging) on the surface of the tissue obscure information and prevent accurate imaging. In order to prevent this surface accumulation, low accelerating voltages (1 Kv and less) have been employed at the expense of resolution. Ideally tissue should be examined fresh, uncoated. Fresh tissues rarely conduct well enough to be examined however, and for this reason some investigators bathe specimens in solutions such as gold chloride and uranyl nitrate which act as a source of ionic material within the tissue. Although this method increases conductivity, it does not make the tissue any less vulnerable to the effects of the vacuum or electron beam.
Ultrastructure of Astroloba and Haworthia Pollen Wall
Authors: Majumdar S. K.
Published: June 2020

Pollen wall morphology has been employed by a number of investigators to assess the interspecific and intergeneric relationships in various groups of plants. Relatively little information is available, however, on the ultrastructure of the pollen wall in the tribe Aloineae. Recent report has dealt with the electron microscope study of Gasteria pollen wall which showed an identical pollen wall anatomy of the four studied species. Since species and genera of the tribe Aloineae are similar in gross chromosome morphology it was considered of interest to study the fine structure of the pollen wall of Astroloba and Haworthia as a prelude to further investigations on the interrelationship among the genera. Pollen of Astroloba spiralis, A. skineri, Haworthia viscosa and H. limifolia was collected fresh and incorporated in agar pellets.
The Effect of Deesterification on the Molecular Organization of Pectin
Authors: Leeper George F. , Dull Gerald G.
Published: June 2020

Negatively stained preparations of high molecular weight pectic acids contain long elementary fibrils about 30A in diameter. Analogous preparations of high ester pectins contain much shorter elementary fibrils of the same diameter.

To investigate the relationship between esterification and elementary fibril length, a 0.1% solution of 86% ester pectin was enzymatically deesterified. The extent of deesterification was monitored during the reaction by titration with NaOH. Samples were removed during deesterification, mixed with an equal volume of 2% PTA (pH 7), and the mixture was applied to film covered grids. Length measurements were made from electron micrographs using an optical micrometer.
The Study of Stalk Rot and Causal Organisms via Scanning Electron Microscopy
Authors: Murphy Judith A.
Published: June 2020

Cooperative SIU Research Includes: A. J. Pappelis, W. E. Schmid, O. Myers, Jr. (Botany); J. N. Bemiller, C. Hinckley (Chemistry); and J. Murphy (Center for Electron Microscopy).

Stalk rot of corn is a disease costing millions of dollars annually. Because of the economic importance of this disease, many studies have been undertaken on the nature of resistance to stalk rot, host-parasite interactions, as well as studies of the various pathogens causing stalk rot.

In studying the number of mechanisms for stalk rot resistance, A. J. Pappelis discovered a positive correlation between stalk rot susceptibility to Diplodia maydis and the pattern of natural cell death of parenchyma cells in the stalk and a positive correlation between disease resistance and the presence of living cells in that tissue.
Filaments in Fibroblast in Pulmonary Alveolar Wall
Authors: Hung Kuen-Shan , Hertweck M. Sue , Hardy John D. , Loosli Clayton G.
Published: June 2020

A small number of fibroblasts (alveolar septal cells, pulmonary interstitial cells, mesenchymal cells) are present in the alveolar areas of the adult lungs. These cells, like fibroblasts elsewhere, may be important in production and maintenance of connective tissue fibers found throughout the lung. Very little attention has been given to these cells in studies of the lungs. Therefore their precise structure and function are not clear. This report demonstrates filaments in the fibroblasts in the alveolar ducts and alveolar walls of the mouse lungs.

The lungs were inflated with 2% glutaraldehyde, post-fixed with 1% osmium tetroxide and processed for electron microscopy. The cell body and processes of the alveolar fibroblast are located in the interalveolar septum (Fig. I).
Aberrant Type C Virus Production in a Cell Line Derived from Balb/3T3
Authors: Savage N. , Hackett A.
Published: June 2020

A cell line, UC1-B, which was derived from Balb/3T3 cells, maintains the same morphological characteristics of the non-transformed parental culture, and shows no evidence of spontaneous virus production. Survey by electron microscopy shows that the cell line consists of spindle-shaped cells with no unusual features and no endogenous virus particles.

UC1-B cells respond to Moloney leukemia virus (MLV) infection by a change in morphology and growth pattern which is typical of cells transformed by sarcoma virus. Electron microscopy shows that the cells are now variable in shape (rounded, rhomboid, and spindle), and each cell type has some microvilli. Virtually all (90%) of the cells show virus particles developing at the cell surface and within the cytoplasm. Maturing viruses, typical of the oncogenic viruses, are found along with atypical tubular forms in the same cell.
Replication of Internal Biological Surfaces
Authors: Nowell J. A. , Pangborn J. , Tyler W. S.
Published: June 2020

Leonardo da Vinci in the 16th century, used injection replica techniques to study internal surfaces of the cerebral ventricles. Developments in replicating media have made it possible for modern morphologists to examine injection replicas of lung and kidney with the scanning electron microscope (SEM). Deeply concave surfaces and interrelationships to tubular structures are difficult to examine with the SEM. Injection replicas convert concavities to convexities and tubes to rods, overcoming these difficulties.

Batson's plastic was injected into the renal artery of a horse kidney. Latex was injected into the pulmonary artery and cementex in the trachea of a cat. Following polymerization the tissues were removed by digestion in concentrated HCl. Slices of dog kidney were aldehyde fixed by immersion. Rat lung was aldehyde fixed by perfusion via the trachea at 30 cm H2O. Pieces of tissue 10 x 10 x 2 mm were critical point dried using CO2. Selected areas of replicas and tissues were coated with silver and gold and examined with the SEM.
Selection of Mutants with Disorganized Septation and Transformation to L forms of Nocardia Corynebacterioides Nom Nov and N. asteroides
Authors: Serrano J. A.
Published: June 2020

Morphology of the cell wall and organization of the cytoplasm of Nocardia corynebacterioides nom nov and Nocardia asteroides ATCC 14597, were examined by electron microscopy after the induction of autolysis using 0.012M ammonium carbonate. Organisms were cultured in casaminic acidbroth modified according to Abrams (1955), medium PPLO (Difco) modified according to Sharp (1954), a modified mixture of electrolytes according to Dienes (1956) and a medium based on amino-acids in proportions of 0.05 mg %. In all of these media we used in an alternate or combined form 1.000 U/ml of penicillin or 100 mg/ml of cycloserine (Sigma). After treatment in ammonium carbonate and culture in the media mentioned above, incubated at 37°C, the growth of the colonies on Agar-peptone and Agar-amino-acid presented a smooth surface and alterations of pigmentation.

Cultures in solid or liquid media were observed by phase contrast and with a JEM 7-A electron microscope. The cells were negatively stained with sodium silicotungstate pH 7.6 and fixed in 2% osmium according to Ryter and Kellenberger.
Extension of The Resolution of The SEM by Holographic Image Enhancement
Authors: Saffir Arthur J. , Stroke George W. , Halioua Maurice
Published: June 2020

It has been assumed that the best resolution of the SEM is apparent in photographs of the CRT. However, an SEM micrograph is an image blurred by both finite beam size and secondary electron emission distribution. Because the secondary electrons are related to the specimen, improved instrumental design cannot extend resolution beyond 100 to 200 Å. Blurred images not only contain considerable information which is not interpretable by the human eye but, fortunately, some of this information can often be extracted. Several mathematically similar techniques have been devised to deblurr images. We have achieved success with a Fourier transform holographic optical analogue technique that was originated and developed by George Stroke and co-workers. Important features of this are: Fourier transforms are accomplished in the image planes of lenses in coherently illuminated systems; deblurring is accomplished by a holographic filter.
Scanning Electron Microscopy of Fish Scales as an Adjunctive Aid in Speciation
Authors: DeLamater Edward D. , Courtenay Walter R. , Whitaker Cecil
Published: June 2020

Comparative scanning electron microscopy studies of fish scales of different orders, families, genera and species within genera have demonstrated differences which warrant elaboration. These differences in detail appear to be sufficient to act as “fingerprints”, at least, for family differences. To date, the lateral line scales have been primarily studied. These demonstrate differences in the lateral line canals; the pattern of ridging with or without secondary protuberances along the edges; the pattern of spines or their absence on the anterior border of the scales; the presence or absence of single or multiple holes on the ventral and dorsal sides of the lateral line canal covers. The distances between the ridges in the pattern appear likewise to be important.

A statement of fish scale structure and a comparison of family and species differences will be presented.

The authors wish to thank Dr. Donald Marzalek and Mr. Wallace Charm of the Marine and Atmospheric Laboratory of the University of Miami and Dr. Sheldon Moll and Dr. Richard Turnage of AMR for their exhaustive help in these preliminary studies.
Rapid Critical Point Drying of Tissues in a Parr Bomb
Authors: Baechler C.A. , Pitchford W. C. , Riddle J. M. , Boyd C.B. , Kanagawa H. , Barnhart M.I. , Hafez E. S. E.
Published: June 2020

Preservation of the topographic ultrastructure of soft biological tissues for examination by scanning electron microscopy has been accomplished in the past by using lengthy epoxy infiltration techniques, or dehydration in ethanol or acetone followed by air drying. Since the former technique requires several days of preparation and the latter technique subjects the tissues to great stress during the phase change encountered during air-drying, an alternate rapid, economical, and reliable method of surface structure preservation was developed. Turnbill and Philpott had used a fluorocarbon for the critical point drying of soft tissues and indicated the advantages of working with fluids having both moderately low critical pressures as well as low critical temperatures. Freon-116 (duPont) which has a critical temperature of 19. 7 C and a critical pressure of 432 psi was used in this study.
Variation With Voltage of Probe Current in the Scanning Electron Microscope
Authors: Cosslett V. E.
Published: June 2020

As the operating voltage Vp of a scanning electron microscope is raised, with an electron source of given emission brightness βE, the current delivered into the probe will increase. The extent of the increase will depend on whether it is the Gaussian probe diameter dG or the total probe diameter dT (determined by the lens aberrations) that is kept constant. It will also depend on whether the probe is limited by spherical aberration alone or also by diffraction.

If the Gaussian probe diameter is constant the maximum current imax into a diffraction limited probe is found by setting the diameter of the disc of least confusion due to spherical aberration dS equal to the diameter of the Airy diffraction disc dD.
A Field Emission Scanning Electron Microscope Operating in the Secondary Electron Imaging Mode
Authors: Komoda T. , Saito S. , Kakinuma Y. , Okura A.
Published: June 2020

The authors have built a surface scanning electron microscope incorporating a field emission electron gun. The gun has a brightness almost three order of magnitude higher than that of the ordinary thermionic electron gun, which is promissing high resolution in the secondary electron imaging mode.

Emission current fluctuation, which is one of the most serious problems in field emission guns, depends on the vacuum condition around the field emission tip. In order to provide a good vacuum environment, the gun assembly in this microscope is located in the center of an ion-pump system which is symmetrically laid out relative to the electron optical axis. Two tips are mounted on a turret holder and they are exchangeable from the outside without disturbing the vacuum in the gun chamber. A stable emission current of the order of 10μA is obtainable at the normal vacuum operation better than 5x10-10 Torr.
SEM Hot Stage Investigation of Surface Bubble Formation and Rupture in Helium-Implanted Rare Earth Films
Authors: Blewer R. S. , Maurin J. K.
Published: June 2020

Helium atoms introduced into metal films by radioactive decay and by ion implantation migrate under the influence of thermal or stress fields, and form expanding bubbles which ultimately deform the lattice and rupture the film surface. Though several studies have been performed to investigate internal migration of submicroscopic helium bubbles, relatively little work has been reported on the influence of gas bubbles on surface microtopography and on the dynamics of bubble rupture. We have investigated localized surface deformation in thin metal films which have been implanted with helium to high doses and then annealed in situ in a scanning electron microscope. The progress of bubble-induced surface deformation and exfoliation in selected areas was observed and recorded photographically. Sequential shots relating the chronological progression of events were made into a time-lapse movie. The influence of (implanted) helium concentration, anneal temperature and post implantation aging on the onset of surface bubble formation and rupture was observed.
On the High Voltage Electron Microscopy (1 MeV) of Biological Thick Sections
Authors: Massover William H.
Published: June 2020

Stereoscopic examination of thick sections of fixed and embedded biological tissues by high voltage electron microscopy has been shown to allow direct visualization of three-dimensional fine structure. The present report will consider the occurrence of some new technical problems in specimen preparation and Image interpretation that are not common during lower voltage studies of thin sections.

Thick Sectioning and Tissue Coloration - Epon sections of 0.5 μm or more that are cut with glass knives do not have a uniform thickness as Judged by their interference colors; these colors change with time during their flotation on the knife bath, and again when drying onto the specimen support. Quoted thicknesses thus must be considered only as rough estimates unless measured in specific regions by other methods. Chloroform vapors do not always result in good spreading of thick sections; however, they will spread spontaneously to large degrees after resting on the flotation bath for several minutes. Ribbons of thick sections have been almost impossible to obtain.
An Experimental High Voltage Scanning Electron Microscope
Authors: Strojnik Ales
Published: June 2020

Crewe and coworkers have shown that by using a field emission source and ultrahigh vacuum a high resolving power is attainable in low voltage transmission scanning microscopes. In the present 0.1 - 1.0 MeV instrument an attempt is being made to combine the advantages of the scanning principle with those of high voltages and in particular to explore the use of the fine high energy, monochromatic electron probe for the scanning of specimens held at or close to atmospheric pressure.

The instrument is designed as an electron optical bench with its axis horizontal ( Fig.1 ) in order to provide a high degree of experimental flexibility. The column is elastically suspended. It can be removed from and reconnected to the accelerator within minutes. Horizontal construction allows an easy mechanical alignment of optical components and a speedy addition of new ones. Accessibility of mechanical controls is better than in vertical HV columns.
High Voltage Electron Microscopy for Thick Sections of Biological Materials Combined with Molecular Tracers
Authors: Yamada Eichi , Ishikawa Harunori
Published: June 2020

One of the advantages of high voltage electron microscopy (HVEM) is the great penetration of electron beam, which permits the examination of thicker sections of resin-embedded biological materials. However, when stained thick sections are examined under the HVEM, all structural details within the whole thickness are brought into focus as superimposed image. Hence, certain structures are not easily observable on such an image, even on the stereo view obtained by specimen tilting technique. To overcome this difficulty, molecular tracers are introduced to the HVEM in an attempt to visualize certain structures selectively.

Mouse kidney and cardiac muscle were examined using ruthenium red and peroxidase as molecular tracers. Thick Epon sections ranging from 0.5 to 3 μ were observed in a JOEL JEM-1000 or a Hitachi HU-1000 HVEM, with an accelerating voltage of 1000 KV. Pictures were taken routinely as stereo pairs using a tilting stage device with ±10° or ±8°.
Hetero-Epitaxy of Group Va Metals on Sapphire
Authors: O'Neal J. E. , Bellina J. J. , Rath B. B.
Published: June 2020

Thin films of the bcc metals vanadium, niobium and tantalum were epitaxially grown on (0001) and sapphire substrates. Prior to deposition, the mechanical polishing damage on the substrates was removed by an in-situ etch. The metal films were deposited by electron-beam evaporation in ultra-high vacuum. The substrates were heated by thermal contact with an electron-bombarded backing plate. The deposition parameters are summarized in Table 1.

The films were replicated and examined by electron microscopy and their crystallographic orientation and texture were determined by reflection electron diffraction. Verneuil-grown and Czochralskigrown sapphire substrates of both orientations were employed for each evaporation. The orientation of the metal deposit was not affected by either increasing the density of sub-grain boundaries by about a factor of ten or decreasing the deposition rate by a factor of two. The results on growth epitaxy are summarized in Tables 2 and 3.
(111) Monocrystalline Nickel Films
Authors: Pratt T.E. , Vook R.W.
Published: June 2020

(111) oriented thin monocrystalline Ni films have been prepared by vacuum evaporation and examined by transmission electron microscopy and electron diffraction. In high vacuum, at room temperature, a layer of NaCl was first evaporated onto a freshly air-cleaved muscovite substrate clamped to a copper block with attached heater and thermocouple. Then, at various substrate temperatures, with other parameters held within a narrow range, Ni was evaporated from a tungsten filament. It had been shown previously that similar procedures would yield monocrystalline films of CU, Ag, and Au.

For the films examined with respect to temperature dependent effects, typical deposition parameters were: Ni film thickness, 500-800 A; Ni deposition rate, 10 A/sec.; residual pressure, 10-6 torr; NaCl film thickness, 250 A; and NaCl deposition rate, 10 A/sec. Some additional evaporations involved higher deposition rates and lower film thicknesses.

Monocrystalline films were obtained with substrate temperatures above 500° C. Below 450° C, the films were polycrystalline with a strong (111) preferred orientation.
Contrast in Scanning Images of Thin Crystals
Authors: Kimoto S. , Hashimoto H. , Takashima S. , Stern R. M. , Ichinokawa T.
Published: June 2020

The most well known application of the scanning microscope to the crystals is known as Coates pattern. The contrast of this image depends on the variation of the incident angle of the beam to the crystal surface. The defect in the crystal surface causes to make contrast in normal scanning image with constant incident angle. The intensity variation of the backscattered electrons in the scanning microscopy was calculated for the defect in the crystals by Clarke and Howie. Clarke also observed the defect using a scanning microscope.

This paper reports the observation of lattice defects appears in thin crystals through backscattered, secondary and transmitted electron image. As a backscattered electron detector, a p-n junction detector of 0.9 π solid angle has been prepared for JSM-50A. The gain of the detector itself is 1.2 x 104 at 50 kV and the gain of additional AC amplifier using band width 100 Hz ∼ 10 kHz is 106.
Oxidation of Silicon Carbide
Authors: Donerty J. E.
Published: June 2020

Most of the available studies of the oxidation of SiC (e.g., [1,2]) find that although the rate of oxidation decreases with time, it does so at a rate somewhat less than would be expected from the normal thickness controlled parabolic rate law. This higher than anticipated rate of oxidation suggests the possibility of small cracks or other such imperfections in the surface which will locally increase the rate of oxidation.

In order to explore this phenomenon further, several samples of fully dense SiC were oxidized in air at 1500°C. After oxidation scanning electron micrographs were taken of the surface and, as can be seen in Figure 1 the oxide surface appears to be covered with crater-like or pock-like features. Figures 2a and b, enlarged portions of 1, clearly show these features to be bubbles which apparently are perculating up through the oxide to the surface.
Differentiation of Asbestos from Other Minerals by SAED
Authors: Grieger Gene R.
Published: June 2020

Because of a correlation between exposure to asbestos and the incidence of lung cancer, there has been an increasing emphasis on the identification and measurement of asbestos in air samples, tissues and mineral products. The general method of identifying fibrous asbestos, the form of the mineral used for manufacturing, has been based on morphological features considered characteristic. Recent studies in our laboratories, however, indicate that selected area electron diffraction (SAED) data are often a necessary supplement to morphological data in the differentiation of asbestos fibers from other mineral fibers, particularly in cases involving quantities dòwn to approximately 10-16 g.

Our studies have shown a number of similarities between the morphology of asbestos fibers and that of other mineral fibers. At a magnification of 30,000X on the transmission electron microscope, we found dozens of minerals with the 3/1 length-to-diameter ratio which defines a fiber. We observed many metal oxides, typical of foundry fumes, which are similar morphologically to amphibole asbestos fibers.
Dark Field Electron Microscopy for Observing the Atoms in Molecules and Crystals
Authors: Hashimoto H.
Published: June 2020

The present author and his coleagues showed the arrangement of Th-atoms in long chain molecule (BTCA, benzentetracarboxylic acid) and crystals (ThO2) can be observed in the dark field images of conventional 100 kV electron microscope. They observed the bright spots which are arranged with the expected spacings in the molecules and crystals and have expected image diameters ( ∼ 4 Å) as shown in Fig.1. Since their observation have been carried out by using a microscope with the spherical aberration constant Cs=0.15 cm, which seems to be rather large for obtaining the resolved images of atoms with detectable contrast in the brightfield image, it is desired that certain theoretical interpretation will give the reason why the resolved image can be obtained in the dark field images.

Using a theory which is originally developed by Scherzer, dark field images of single atoms and chain of atoms in long chain molecules and crystals have been calculated.
Morphology of γ Precipitates in Ni-Rich γ'-Ni3 (Al,Ta)
Authors: Kear B. H. , Doherty J. E. , Giamei A. F. , Lemaire L. P.
Published: June 2020

The microstrueture of a commercial nickel-base alloy normally consists of a coherent, cuboidal precipitate of γ’ (alloyed Ni3Al) in a matrix of γ (Ni solid solution). Recently, Ham et al., working with the ternary alloy 78Ni-l8Al-4Ti (a/o), have shown that by appropriate heat treatment a completely novel microstrueture can be developed, in which the matrix is γ’ and the precipitate is platelet γ. The present study represents an extension of this work, and reports some new findings on precipitation of γ in γ’ in alloys similar in composition to the Ni-Al-Ti alloy but with Ta replacing Ti.

The alloys used were solutionized in the range 2200-2400°F and aged at l600°F for 24hrs (giving ∼ 10 vol. percent of γ in γ’). According to our most recent findings, unlike the binary system, the solubility of γ’ for γ reaches a maximum at ∼ 2200°F in these alloys.
A Diffraction Contrast Study of Displacement Faults in an Ordered Ni-Al-Ti Alloy
Authors: Strutt P. R. , Ingram J. C. , Polvani R. S.
Published: June 2020

A study has been made of Ni-Al-Ti alloys with compositions along the tie-line between the β-NiAl and Ni2AlTi phases; Ni2AlTi has the Heusler-type structure. The micrographs in Figs. 1-4 are from an alloy with composition 63.8 wt% Ni, 20.5 wt% Al, and 15.6 wt% Ti. A fine precipitate forming a “tweed” or modulated structure was observed (see Figs. 2, 3, and 4), and in the diffraction pattern strong Heusler ordering reflections were evident. of particular interest are the unusual displacement faults, which unlike those observed by Ball in Al-rich NiAl generally do not lie in specific crystallographic planes, but are high convoluted as shown in Fig. 1.

In Fig. 2 each fault in the array A to B terminates at a dislocation, and it was deduced that these dislocations had a ao[001] Burgers vector since they were invisible when g = [110], and [200].
A New Low-Cost Image Intensifier for Transmission Electron Microscopy
Authors: Heinemann Klaus , Poppa Helmut
Published: June 2020

An efficient electron microscope image intensifier (EMII) chain with closed-circuit television image display should feature the following characteristics:

- The signal of a single incoming electron should be raised well above the equipment noise.

- The spatial resolution of the EMII-chain should not be worse than the product of available electron optical magnification and the desired specimen resolution.

- The spatial resolution of the TV-system, multiplied by the magnification factor between the intensified image and its size on the camera tube face, should not be better than the spatial resolution of the image intensifier (the lowest reasonable bandwidth should be selected).

In this paper we present a new type of EMII system which fulfills these basic features within the framework of a comparatively high performance-to-cost ratio system. We have been using two medium-resolution microchannelplates in series as an image intensifier (resolution approximately 50 microns), featuring a gain of more than 106with practicably negligible noise.
Preliminary EM6 Modifications for in situ Chemical Vapor Deposition
Authors: Kenty J. L.
Published: June 2020

An AEI EM6 electron microscope is being modified for in situ chemical vapor deposition. The objective is to observe the nucleation and growth kinetics and structure of silicon deposited by SiH4 gas pyrolysis on substrates of sapphire (single crystal α-Al2O3).

An Edwards DCB2 thermoelectrically cooled baffle has been installed using a simple adapter which permitted attachment without drilling or cutting of the EM6 frame or vacuum system. Prior to installation the measured contamination rate was 240Å/min; afterward the contamination rate was less than 100 Å/min.

An auxiliary pumping system is mounted to the left rear of the column and attached by a special stainless steel flexible bellows to the pumping port at the rear of the specimen chamber. The auxiliary system has an ultimate presure <1 × 10-6 torr, but the measured pressure in the specimen chamber was no better than 1 × 10-5 torr, due primarily to the high outgassing rate of the beam deflector coil immediately above the specimen chamber.
Diffraction Analysis by Computer
Authors: Ploc R.A.
Published: June 2020

Several computer programs have been written recently to aid in analysing electron diffraction data. A summary of these programs and the manner in which they inter-relate will be given.

The programs are called, PATTERN, SADSP, RING, STEREO and CCRYS, the functions of which are; to calculate and plot simulated SAD spot patterns, to analyse spot and ring data, to produce stereographic projections and to calculate structure factors respectively. Acquisition of the programs should be through written request to the author.

By the application of the programs SADSP and RING it will be shown that effective chemical identification of small amounts of material can be performed in the TEM. For instance, small acicular growths formed on the inside of a high-pressure water loop containing radio-active materials have defied conventional analysis because of their small size (200 Å thick, 1-3 μm long and high) and location (on the surface of a “crud”deposit).