bluuebunny/crossref_metadata_2025 huggingface dataset:
The Double-Field Condenser Objective Lens
Authors: Anderson K. , Brookes K. A. , Fibow D. C.
Published: June 2020

The illumination system of the conventional transmission electron microscope is designed to provide an adequate level of coherent illumination over the field of view being examined. The additional requirement of providing the maximum possible current into very small (sub-micron) focussed spots, as is required by X-ray microanalysis for example, necessitates a probe forming lens with a very short working distance and has previously been met by using either a mini-lens or the prefield of the objective lens when used in the Single-Field Condenser-Objective mode.

The SFCO gives the smallest spot size and aberration parameters but suffers from the disadvantage that the illumination and imaging fields are not independently controllable.
Field Distribution of Strongly Excited Magnetic Lenses
Authors: Strojnik M.
Published: June 2020

Magnetic lenses operating in partial saturation offer two advantages in HVEM: they exhibit small cs and cc and their power depends little on the excitation IN. Curve H, Fig. 1, shows that the maximal axial flux density Bz max of one of the lenses investigated changes between points (3) and (4) by 5% as the excitation varies by 40%. Consequently, the designer can relax the requirements concerning the stability of the lens current supplies. Saturated lenses, however, can only be used if (i) unwanted fields along the optical axis can be controlled, (ii) 'wobbling' of the optical axis due to inhomogeneous saturation around the pole piece faces is prevented, (iii) ample ampere-turns can be squeezed into the space available, and (iv) the lens operating point covers a sufficient range of accelerating voltages.
The Formation of Fault-Pairs in F.C.C. Crystals
Authors: Mahajan S.
Published: June 2020

When two 1/2 <110> dislocations of different, but coplanar, Burgers vectors interact repulsively, they appear to combine to form three Shockley partials having identical Burgers vectors. These partials bound a coupled pair of intrinsic and extrinsic faults, and this arrangement has been designated as a fault-pair (1). The intriguing observation is that, even though the interaction is repulsive in nature, fault-pairs can evolve in the absence of pile-ups. A mechanism has been proposed that can satisfactorily account for the preceding observation. In addition, experimental evidence in support of the mechanistic details has been developed by examining the fault-pairs in deformed Co-6.25 at. % Fe and Cu-8.5 at. % Ge alloys by transmission electron microscopy. Figures (a) and (b) show the two configurations which have been examined in detail. In Fig. (a), two 1/2 <110> glide dislocations, D1 and D2 undergo some realignment and come together in the absence of a pile-up to form a fairly long fault-pair.
Determination of Energy Spread and Source Size by Optical Diffraction
Authors: Frank J.
Published: June 2020

Since the effect of energy spread and angular spread of illumination on the contrast transfer function is known from theoretical investigations, these experimental parameters can in turn be obtained by careful analysis of electron micrographs. For Gaussian energy spread (halfwidth △E), negligible voltage and current fluctuations and a Gaussian source distribution (half-width α), the coherent transfer function for monochromatic electrons appears multiplied with the envelope function

(θ scattering angle, λ electron wavelength, E0energy, △z defocus; Cc, Cschromatic and spherical aberration constants). This causes an attenuation of the image Fourier transform at high spatial frequencies and is responsible for the fact that the visible bandlimit in optical diffraction patterns is well below the aperture limit.
Cellular Precipitation of Gamma Prime in Iron-Nickel Based Alloys
Authors: Gelles D. S.
Published: June 2020

A coherent precipitate known as gamma prime develops in iron-nickel base alloys when alloying additions of aluminum and titanium are included. The gamma prime phase is an ordered fcc structure of Ll2 symmetry having an Ni3(A1, Ti) composition. Gamma prime is generally found as a fine spherical or cubic precipitate, uniformly distributed throughout the material. Imaging is usually difficult because lattice mismatches are small and only superlattice reflections of weak intensity are available for dark field imaging. This paper presents evidence that the gamma prime phase can be formed by discontinuous precipitation, developing a typical cellular structure.

An experimental alloy, Fe-14.9Cr-34.8Ni-l.5Al-l.98Ti-.004C (weight percent), has been given a solutionizing treatment of 1145°C for 1 hour followed by an air quench and an aging treatment of 815°C for 1 hour. Examination of the microstructure by TEM indicated that a cellular precipitate had developed extensively at grain boundaries.
Direct Observation of Radiation Induced Precipitation in High Voltage Electron Microscope
Authors: Wu Wei-Kuo , Washburn Jack
Published: June 2020

Long needle-shaped radiation induced precipitates oriented along <110> directions were first reported by Nes and Washburn from observation using hot stage high voltage electron microscopy. Similar long rod-like defects have also been observed in boron ion implanted silicon.

Our recent results show that most long rod-like defects formed during postimplantation annealing of boron ion implanted silicon are boron precipitates. The cause for the formation of these long rod-like defects is assumed to be replacement of substitutional boron by silicon selfinterstitials.

To substantiate this mechanism two samples were irradiated in the high voltage electron microscope. Sample A was a boron doped <111> oriented silicon of resistivity 0.75 Ω-cm (2.5x10l6 B/cm3) and sample B was phosphorous doped, of resistivity 2 Ω-cm (2.7x10l5 p/cm3).

Figure 1 shows the sequential development of long rod-like defects in sample A held at 620°C during irradiation with 650 keV electrons.
Electron Microscopy of U-6.3 wt% Nb Alloy
Authors: Ehlinger A. O. , Staudhammer K. P. , Mille A. R.
Published: June 2020

Addition of small amounts of niobium to uranium generally produces an alloy that has an increase in strength and greater corrosion and oxidation resistance. While many investigators have studied the physical metallurgy and mechanical properties of dilute uranium alloys, to date there have been no studies utilizing transmission electron microscopy to study the precipitation behavior of the U-6.3% Nb alloy.

The present investigation was undertaken in order to determine by TEM the mode of precipitation of the U-6.3% Nb alloy when aged at various times and temperatures. Samples in the form of charpy bars, were treated at 850°C for 30 min., and water quenched (γ - quenched). These samples were then aged for 180 min. at 250°C, 385 min. at 254°C, and 72 min. at 358°C, to give 100, 117, and 160 KSI-yield strength respectively. The resulting microstructures were examined in a Hitachi-Perkin Elmer H.U. 200 F electron microscope operated at 200 KV; employing a goniometer tilt stage.
Identification of Asbestos Fibres in a Water Sample by X-Ray Microanalysis
Authors: Brookes K. A. , Finbow D. , Samuel Madeleine
Published: June 2020

Investigation of the particulate matter contained in the water sample, revealed the presence of a number of different types and certain of these were selected for analysis.

An A.E.I. Corinth electron microscope was modified to accept a Kevex Si (Li) detector. To allow for existing instruments to be readily modified, this was kept to a minimum. An additional port is machined in the specimen region to accept the detector, with the liquid nitrogen cooling dewar conveniently housed in the left hand cupboard adjacent to the microscope column. Since background radiation leads to loss in the sensitivity of the instrument, great care has been taken to reduce this effect by screening and manufacturing components that are near the specimen from material of low atomic number. To change from normal transmission imaging to X-ray analysis, the special 4-position specimen rod is inserted through the normal specimen airlock.
Charging of Small Particles in the Scanning Electron Microscope
Authors: Krakow W. , Nixon W. C.
Published: June 2020

Charging effects in the scanning electron microscope (SEM) have been investigated and various contrast mechanisms have been explained which include both the primary beam and secondary electron trajectories and take into account specimen parameters. In particular, Weitzenkamp measured potentials of cylindrical fibers which could be suspended above a replica of a ruled surface to measure charge density on these organic polymer materials.

We have been able to obtain the equivalent information on the charge density from SEM micrographs of small charged particles. Fig. 1, shows a backseattered electron image of a 10μm polystyrene particle supported on a gold coated linear hologram grating having spacing of approximately 3.6μm. The grating distortion indicates a strong negative charge on the particle which deflects the 10 kV primary beam. The grating distortion is asynmetric due to a specimen tilt of 70 degrees.
Mitochondrial Reconstructions Based on Serial Thick Sections and HVEM
Authors: Paulin Jerome J.
Published: June 2020

Within the past decade it has become apparent that HVEM offers the biologist a means to explore the three-dimensional structure of cells and/or organelles. Stereo-imaging of thick sections (e.g. 0.25-10 μm) not only reveals anatomical features of cellular components, but also reduces errors of interpretation associated with overlap of structures seen in thick sections. Concomitant with stereo-imaging techniques conventional serial Sectioning methods developed with thin sections have been adopted to serial thick sections (≥ 0.25 μm). Three-dimensional reconstructions of the chondriome of several species of trypanosomatid flagellates have been made from tracings of mitochondrial profiles on cellulose acetate sheets. The sheets are flooded with acetone, gluing them together, and the model sawed from the composite and redrawn.

The extensive mitochondrial reticulum can be seen in consecutive thick sections of (0.25 μm thick) Crithidia fasciculata (Figs. 1-2). Profiles of the mitochondrion are distinguishable from the anterior apex of the cell (small arrow, Fig. 1) to the posterior pole (small arrow, Fig. 2).
An Image Reconstruction System Applied to High Voltage Microscopy
Authors: Johnson D. E.
Published: June 2020

Increased specimen penetration; the principle advantage of high voltage microscopy, is accompanied by an increased need to utilize information on three dimensional specimen structure available in the form of two dimensional projections (i.e. micrographs). We are engaged in a program to develop methods which allow the maximum use of information contained in a through tilt series of micrographs to determine three dimensional speciman structure.

In general, we are dealing with structures lacking in symmetry and with projections available from only a limited span of angles (±60°). For these reasons, we must make maximum use of any prior information available about the specimen. To do this in the most efficient manner, we have concentrated on iterative, real space methods rather than Fourier methods of reconstruction. The particular iterative algorithm we have developed is given in detail in ref. 3. A block diagram of the complete reconstruction system is shown in fig. 1.
High Resolution Structure Determination of Unstained Biological Molecules
Authors: Unwin P. N. T . , Henderson R.
Published: June 2020

Structure determination of unstained biological molecules is made difficult by their sensitivity to damage by electrons. Because of this, resolution in an image of an isolated molecule, exposed to a dose small enough to avoid much damage, is limited by electron noise.

It is well known however that statistical limitations of such a nature can be overcome in the case where the molecule forms part of a crystalline array. The information from the large number of unit cells can be combined so that the genuine detail is reinforced and random statistical fluctuations are averaged out.

We have made use of this redundancy principle in determining, by Fourier methods, the projected structures of beef liver catalase and of the purple membrane from Halobacterium halobium. These specimens are about equally sensitive to irradiation and are typical of proteins (see fig. 1).

Both specimens were immersed in glucose on the microscope grid.
Membrane Organelles in Developing Hamster Frontal Cortex
Authors: Tank Buschraann MB.
Published: June 2020

Changes in the morphology of the protein-synthetic organelles in pyramidal cells from the frontal cortex were studied in the newborn, 5-, 10-, 15-, 20- day, and adult golden hamster (Mesocricetus auratus). The rough endoplasmic reticulum (RER) was of special interest since it forms the characteristic Nissl substance of adult neurons, as well as other occasional specializations including the subsurface cistern, the lamellar body, the nebenkem, the multilaminated body, the annulate lamella, and the spine apparatus. During the course of this investigation, a sequential pattern was noted in the appearance of the subsurface cisterns and the lamellar bodies, which were the only two specializations of RER observed.

The animals were perfused with glutaraldehyde-paraformaldehyde in cacodylate buffer (pH 7.3) after the method of Peters. Tissue samples were subsequently post-fixed in 2% osmium tetroxide, dehydrated in acetone, and embedded in Epon-Araldite resin.
Insect Virus Infection of a Poikilothermic Vertebrate Cell Line: Electron Microscopy
Authors: Kimura Michio , Mcintosh Arthur H. , Maramorosch Karl
Published: June 2020

Recently McIntosh and Kimura have demonstrated the replication of Chilo iridescent virus (CIV) in a poikilothermic vertebrate "C-Type virus" carrying cell line (USW . Now an attempt has been made to visualize attachment and penetration of CIV. Monolayer cultures of VSW cells were inoculated as described earlier, then fixed at various intervals (10 min - 72 hrs after inoculation) with 1.5% glutaraldehyde, buffered at pH 7. 4 with 0. 1 M cacodylate. Virus attachment, penetration into cells, and completely formed CIV particles were detected in VSW cells 24 hrs post inoculation (Fig. 1). Hexagonal structures characteristic for the Irido virus group, as well as incomplete virions were also observed (arrow, Fig. 1). Budding of CIV occurred from the cell surface (Fig. 2). "C-type" particles and CIV coexisted in the same cells (Fig. 3).
Replicative Forms of a MSV (FELV) Pseudotype Virus
Authors: Al-Adhami R. A. , Chapman A. L.
Published: June 2020

We have reported on the replication of morphologically aberrant virus particles found in both Crandall cat kidney cell lines (CrFK2) and feline embryo fibroblasts (FEF) following infection with a pseudotype resulting from co-centrifugation and designated as MSV(FeLV). Another Crandall cell line (CrFKl) infected with this pseudotype did not show any transformation and only normal type C viruses were seen by electron microscopy. There appeared to be a direct correlation between transformation of the cells and the presence of aberrant progeny virus. There was evidence that there were two morphologically distinct normal type C viruses and an aberrant form replicating in those cells that were transformed.

It was the purpose of this report to extend our study by using another pseudotype obtained from Dr. Fischinger that was prepared by infecting S+L- cells with FeLV. We then examined the infectivity and filtrability of the progeny virus.
Scanning Electron Microscopy of Non-Mechanical Cryofractured and Paraffin Sectioned Root Sheath of Epilated Human Hair
Authors: Uptgraft G.
Published: June 2020

Scanning electron microscopy studies of human hair defects have been previously confined to descriptions of variation in cuticle morphology and general appearance of the shaft. While the general structure of the hair shaft, i. e., nodes, longitudinal invaginations and twists, occur in regular patterns for given diagnostic categories, there is some question as to the validity of using cuticle morphology as a diagnostic index, since variation within a given subject is usually greater than between subjects. Also, there is a limited amount of information to be obtained from such studies since the metabolically active part of the structure is not visualized. Consequently, the present investigation was initiated to delineate the root sheath through which the emerging hair shaft travels.

The general structure of the root sheath is depicted using paraffin sections (Figs. 1,4), and non-mechanical cryofractured material (Figs. 2,3).
Morphology and Transplantability of Tumors Derived from Clones of the H-4II-E Rat Hepatoma Cell Line
Authors: Lovig C. A. , Nordquist R. E. , Muragishi H. , Bottomley R. H.
Published: June 2020

Previous studies in this laboratory using the H-4II-E rat hepatoma cell line indicated that heterotransplantation of these cells into the cheek pouch of hydrocortisone treated hamsters resulted in the selection of cells with characteristic chromosome constitution and phenotype differing from the original H-4II-E cells.

This study was designed to see if cells cloned from the H-4II-E cell line and differing in their genetic composition displayed differences in their ability to be transplanted into AxC rats and if the tumors produced by these cloned cell lines differed in their morphology.

For this study five cloned cell lines were chosen based on their modal chromosome number and a sufficient number of T-75 flasks set up for each cell line such that transplantation experiments and karyotypic analysis could be carried out on cells of the same passage generation. Transplantation was done by innoculating 1x106 cells subcutaneously into each thigh of 10 AxC rats.
Ultrastructural Acridine Orange and Autoradiographic Studies in Acute Leukemia Bone Marrow Cells
Authors: Ahearn M. J. , Trujillo J.M.
Published: June 2020

Previous studies have established that a high frequency of ultrastructural nuclear blebs occur in the bone marrow cells of acute leukemia patients with an aneuploid cytogenetic clone.

Utilizing the nuclear bleb as an interphase morphological marker, nuclear probe studies with acridine orange and H3 thymidine were performed on these aneuploid leukemic blast cells. The deposition of Frenster's electron dense reaction product at the binding site of acridine orange to DNA has been employed to delineate the active extended euchromatic portions of the cell nucleus. These studies have indicated a variation in the pattern of the euchromatic binding in cells from acute leukemia patients bearing the nuclear bleb and an aneuploid clone when compared with the non-blebbed or diploid component of the bone marrow. The blebbed cells demonstrate a reduced acridine orange binding produce while similar staged non-blebbed cells are heavily marked as seen in Fig. 1. This observation is of interest in view of concomitant autoradiographic studies demonstrating a diminished H3thymidine incorporation observed ultrastructurally in the same nuclear blebbed cells.
Ultrastructural Fiber Typing in Normal and Diseased Human Muscle
Authors: Payne Claire M. , Stern Lawrence Z. , Curless Richard G. , Hannapel Linda K.
Published: June 2020

Histochemical analysis of muscle biopsies is well established as being essential for the definitive evaluation of neuromuscular disorders. The usefulness of electron microscopy as both a diagnostic and research tool in the study of diseased skeletal muscle has also been demonstrated. Reliable cross-correlation between histochemical and electron microscopic findings would appear to be useful. Based on the variations of the histochemical reaction for myofibrillar ATPase, there appear to be three constant categories in normal human skeletal muscle (types I, IIA and IIB). An attempt has therefore been made to define the ultrastructural correlates of each of these three major fiber types based on the measurements of Z-line and M-line widths. We have recently had the opportunity to study biopsied muscle from patients with 3 muscle disease states in which there was a relative deficiency of at least one of the 3 fiber types.
Some Observations on the Ultrastructure of the Surface of Normal Human Stomach Mucosa
Authors: Watson John H. L. , Goodwin Jessica , Fard Ebrahim
Published: June 2020

This report is part of a larger study being conducted by scanning electron microscopy (SEM) with concurrent light (LM) and transmission microscopy (TEM) on gastroscopic biopsies of normal and diseased human stomachs. Biopsies are taken of areas after endoscopical determination of their normalcy and/or pathology, confirmed later by LM. During the study, new and unusual observations were made by SEM on the normal stomach, and it is these which are reported here. The specimens were fixed immediately in cacodylate-buffered glutaraldehyde, were critical point dried with CO2 and coated with Au-Pd. After scanning, the same specimen was embedded in Araldite for thin sectioning and TEM, Fig. 1. At low power by SEM, the surface was found to have a reticular appearance. In Fig. 2 this appearance is seen to be due to the concentration toward the cell margins of rounded, short projections of the epithelial surface.
Observation of Domains and Phase Separation in Hydrated Lipid Bilayers
Authors: Hui S. W. , Parsons D. F.
Published: June 2020

The domain structure and phase separation in lipid single bilayers were observed directly by selective area electron diffraction (SAED) and selected reflection dark field electron microscopy (SRDFEM), using an environmental stage for a Siemens Elmiskop IA. The specimens were viewed in a fully hydrated state in the temperature range between 0°C and 50°C. Below the transition temperature, three orders of a hexagonal pattern were recorded, whereas diffuse rings only were seen above the transition temperature.

Selective area electron diffraction were done by restricting the illumination area to few micrometers in diameter, using a pointed filament and a 10 μm second condenser aperture. Below the transition temperature of dipalmitoylphosphatidylchoiine bilayers, differentially oriented diffraction patterns were distinguishable between adjacent membranes areas (domains) five micrometers apart. Occasionally, two or more superimposed patterns were recorded from the same area, indicating the observation area covered several domains.
Lipid Droplet Accumulation in Cardiac Muscle Cells of the Bat: Induction by Reserpine and Antagonism by Atropine
Authors: Hagopian Martin , Nunez Eladio A. , Gershon Michael D.
Published: June 2020

Reserpine has been shown to induce the accumulation of large numbers of lipid inclusions in cardiac muscle cells of the bat. This effect of reserpine is seen 24 hours after a single injection of 5 mg/kg of the drug. Since the action of reserpine can be antagonized by chemical sympathectomy with 6-hydroxydopamine and mimicked by norepinephrine, we have postulated the involvement of the cardiac sympathetic innervation in mediating reserpine's effect. In the present investigation we have examined the ability of atropine to prevent the accumulation of lipid droplets in cardiac muscle after a single injection of reserpine. Two dose schedules of atropine were tried. A high dose consisted of 3 injections, 9 mg/kg each, given intraperitoneally at 8 hour intervals beginning one hour prior to challenge with reserpine. A low dose consisted of 2 mg/kg given the same way. Left ventricular muscle was examined by electron microscopy and the relative cardiocyte volume occupied by lipid droplets was quantitated from electron micrographs by point count planimetry.
Heavy Meromyosin Binding Studies of Myocardial Cells in Cardiac Lethal Mutant Salamanders (Ambystoma Meximanum
Authors: Lemanski Larry F.
Published: June 2020

A naturally-occurring genetic mutation, designated c for “cardiac lethal”, was discovered in Ambystoma meximanum. The effect of homozygosity for recessive gene c is the absence of a heart beat, even though initially heart development appears normal. Mutant embryos are first distinguishable form their normal siblings at Harrison stage 34, when the normals develop contracting hearts. The mutant hearts at this stage, upon gross examination appear structurally normal but fail to beat. Nevertheless, the mutants survive through stage 41, which is about 20 days beyond the heart-beat stage and exhibit normal swimming movements indicating that gene c does not affect skeletal muscle. Electron microscopic studies of normal hearts at stage 34 reveal that the myocardial cells contain organized myofibrils; these myofibrils first form directly beneath the plasma membrane. By stage 41, the normal myocardial cells contain numerous well-organized myofibrils and thus have now become highly differentiated muscle cells.
Fragmentation of the Actin Filaments by Acute Pressure Overload to the Right Ventricle of the Conscious Dog.
Authors: Adomian Gerald E. , Laks Michael M. , Swan H.J.C.
Published: June 2020

We have postulated in a study of the isolated cat papillary muscle that the disparity between muscle length and sarcomere length may be the result of myofibrillar fragmentation. In contrast, Saphir and Karsner demonstrated in the rabbit myocardium subjected to an acute pressure overload, that segmentation or separation of intercalated discs occurred, and not myofibrillar fragmentation.

In order to determine whether the myocardial fragmentation produced in the in vitro study has pathophysiological significance in the intact myocardium, tissues were studied from the right ventricle of the conscious dog subjected to an acute pressure overload.

In order to produce the overload, we utilized a specially designed triple lumen pulmonary artery balloon distension catheter. This catheter can measure simultaneous pulmonary arterial and right ventricular pressures. The catheter was inserted through the jugular vein and wedged under flouroscopic control in a branch of the pulmonary artery. The balloon was situated in the main pulmonary artery.
An Ultrastructure Study of Tumor Cells of Haworthia Plants Induced by 2,4-D
Authors: Sullender J. S. , Majumdar S. K.
Published: June 2020

Treatment of normal callus cells of Haworthia variegata with high concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) promoted the development of tumor-type growth. At low concentrations (1 and 2 mg/liter), 2,4-D had little adverse effects on the growth and morphogenesis of the callus, however, in some tubes abnormal-appearing roots were detected. Calli on the media containing 5, 10 and 20 mg/liter of 2,4-D developed pink-brown pigmentation, produced numerous minute nodules, induced tumor-type growth, showed little differentiation and produced abnormal roots and leaves. Ultrastructure studies of auxin-induced tumors in some plants have been made by several investigators, however, no information is available on the fine structure of the 2,4-D induced tumor cells of Haworthia plants. Tissues from tumor and control groups were fixed in 2% osmium tetroxide, post-fixed in 4% glutaraldehyde, and embedded in Epon 812. Sections were cut on a Porter-Blum MT-2 ultramicrotome, stained with uranyl acetate-lead citrate and examined on a Philips Model 201 transmission electron microscope operating at 60 kV.
Dormant and Germinating Diplodia Maydis Spores: Ultrastructure and Elemental Composition
Authors: Murphy Judith A. , Thompson Mary R. , Pappelis A.J.
Published: June 2020

Diptodia maydis is one of the fungal pathogens causing stalk rot of corn. Previously we investigated the gross morphology of D. maydis on synthetic and natural substrates by SEM and established preparation procedures for D. maydis. The purpose of the present study was to compare the ultrastructure of D. maydis spores in thin sections with SEM results and in addition examine the elemental composition and distribution in dormant and germinating spores of D. maydis.

SEM: Germinating and non-germinating spore cultures were double fixed in glutaraldehyde followed by OsO4. Samples were dehydrated in a graded series of alcohols thru 100%, then thru Freon TF and critical point dried with Freon 13 in a Bomar 900EX CPD. Specimens were mounted on SEM stubs, coated with carbon and PdAu and examined in a Cambridge Mark IIA SEM operated at 20 KV.

TEM: Samples were double fixed with glutaraldehyde followed by OsO4, then dehydrated and embedded in Epon 812. Sections were stained with dipotassium tetramethyl osmate and examined in an Hitachi HU11AB TEM.
Sporocyte Development in the Musci. I. Three Genera of the Pottiaceae
Authors: Seabury F. , Mueller D.M.J.
Published: June 2020

Sporogenes is in three members of the Pottiaceae: Weissia controversa Hedw., Acaulon muticum var. rufescens (Jaeg.) Crum, and Astomum muhlenberqianum (Sw.) Grout was studied using light, transmission and scanning electron microscopy with particular emphasis on the formation of the wall layers. McClymont and Larson, in a study of the mature spores of nine mosses representing seven families, found them to have walls of four layers. In this investigation four wall layers were observed in all genera studied. They are opaque layer, exine, perine and intine.

The opaque layer begins to form while the spores are still contained within the sporocyte wall. Fig. 1 of Weissia exhibits a series of thin, trailing membranous projections which will later coalesce and flatten against the spore boundary. The opaque layer appears first on the distal surface of the spore.
The Mouse Testis as a Model for the Study of Age Related Fine Structural Changes
Authors: Johnson J.E. , Miquel J.
Published: June 2020

In studying the morphology of aging cells, it is generally concluded that different changes occur in fixed postmitotic cells as compared to those cells which divide actively throughout life. The testis appears to be an excellent model for a comparative investigation of such changes, since it contains some cells which are essentially non-dividing in adulthood (Sertoli cells and interstitial cells) as well as other cells which divide continuously in mature animals (spermatogonia and spermatocytes).

We have examined, by light and electron microscopy, the testes of numerous C57BL/6J mice at ages ranging from 3 to 30 months. All tissues were fixed by vascular perfusion with paraformaldehyde and glutaraldehyde mixtures in phosphate buffer.

Sertoli cells (Fig. 1) and interstitial cells (Fig. 2) in aging animals contain a large number of dense bodies (presumably lipofuscin). On the other hand, dense bodies are not seen in spermatogonia, spermatocytes or spermatids (Fig. 1).
Fine Structure of the Channel Catfish Spermatozoa, Ictalurus Punctatus
Authors: Henderson Vernon
Published: June 2020

The fine structure of fish spermatozoa has received less attention than various mammalian species. The basic ultrastructural features of several species of fish have been established but with some degree of confusion. This confusion may well be due to the structural diversities which render generalization difficult. Berrill ('70) stated that male gametes of animals typically have but one flagellum with rare exceptions such as the toad fish which has two. This paper describes the fine structure of the lobe (cytoplasmic droplet or neck region) which provides information to clarify its distinctiveness in fish spermatozoa. Accounts are given of an anterior projection and a biflagellated condition.
Electron Microscopic Study of Freshly Fixed and Time-Delay Fixed Tissues in Rat
Authors: Lim B. S. , Solomon J. D.
Published: June 2020

In a pathology laboratory, many tissues which are submitted or made available for electron microscopic study are obtained from autopsy. Morphological changes due to postmortem delay which may not be visualized when studied with a light microscope are readily seen with the electron microscope. Because of this, it is important to make a comparative study of the freshly fixed and time-delay fixed tissues assimilating those obtained at autopsy. This work presents the results of morphological changes in the brain, heart, kidney, liver, and striated skeletal muscle of the rat with a postmortem time-delay of 24 hours. In the case of striated muscle the time delay was up to 48 hours before fixation.

Methods and Materials A 62 day old male rat of the Sprague Dawley strain, weighing 410 grams was used in this experiment. The rat was anesthetized with nembutal and quickly opened. The brain, heart, liver, kidney, and a small piece of femoral muscle were quickly removed.
Thin Carbon-Aluminum Films for Dark Field Electron Microscopy of DNA
Authors: Ruben George , Siegel Benjamin M.
Published: June 2020

Carbon substrate films prepared by indirect evaporation have important features needed for the visualization of DNA in dark field work. These indirectly deposited carbon films can be made with minimum granularity and with a support thickness of about 10-20Å. They can mechanically withstand contact with aqueous solution and the high beam currents at condenser crossover in the microscope. The surface of freshly made carbon films used within a few hours wets and adsorbs DNA prepared by the Kleinschmidt method with its cytochrome c film. The low frequency binding on these carbon substrates even when fresh or after ultra-violet light activation makes them a marginal substrate film for DNA work (1,2). Unfortunately these films also lose their ability to wet and bind naked DNA or DNA spread with a basic protein within a period of a day.
Potassium and Branchial Nerve Stimulation as Physiologic Regulators of Ciliary Motion in the Bivalve Mytilus Edulis
Authors: Paparo Anthony A. , Murphy Judith A.
Published: June 2020

The lateral cilia(LC) on the gill of the bivalve Mytilus edulis are under neural control. Electrical stimulation (0.1V, 10Hz biphasic, 2msec duration for 3 min) of the branchial nerve(BN) increases the average rate of beating of LC, probably by a mechanism involving the release of 5-hydroxytryptamine (5 HT). Gills previously conditioned with [K]> 30mM enhanced cilioexcitatory effect of exogenous 5-HT.This study investigates the effect of [K] on endogenous neuronal release of 5-HT in intact and severed BN/gill preparations.

Gill preparations were isolated and subsequent stroboscopic measurement of LC were made. When nerve stimulation was part of the experiment, the BN was exposed and an electrode placed at its point of departure from the visceral ganglion(VG).

For SEM, specimens were doubly fixed in 3% glutaraldehyde in .05 M s-collidine, pH 7.2, for 30 min. washed, and then into Parducz fixative (6 parts of 2% aq. OSO4 to 1 part saturated aq. HgCl2) for 20 minutes. Samples were dehydrated through a graded series of alcohols through 100%, into Freon TF, and critical point dried in Freon 13 in a Bomar 900 EX CPD.
Albumin-Induced Endocytic Vacuoles in Tetrahymena Pyrijormis
Authors: Brenner L. J. , Osborne D. G. , Schumaker B. L.
Published: June 2020

Exposure of the ciliate, Tetrahymena pyriformis, strain WH6, to normal human or rabbit sera or mouse ascites fluids induces the formation of large cytoplasmic bodies. By electron microscopy these (LB) are observed to be membrane-bounded structures, generally spherical and varying in size (Fig. 1), which do not resemble the food vacuoles of cells grown in proteinaceous broth. The possibility exists that the large bodies represent endocytic vacuoles containing material concentrated from the highly nutritive proteins and lipoproteins of the sera or ascites fluids. Tetrahymena mixed with bovine serum albumin or ovalbumin solutions having about the same protein concentration (7g/100 ml) as serum form endocytic vacuoles which bear little resemblance to the serum-induced LB. The albumin-induced structures (Fig. 2) are irregular in shape, rarely spherical, and have contents which vary in density and consistency. In this paper an attempt is made to formulate the sequence of events which might occur in the formation of the albumin-induced vacuoles.
The Accumulation of Lipofuscin in the Epithelium of the Midgut of the Aging Housefly, Musca Domestica.
Authors: Duncan S.L. , Sohal R.S. , Allison V.F.
Published: June 2020

Since somatic tissues in adult dipteran insects are entirely composed of post-mitotic cells, they are especially suited to studies concerned with structural alterations associated with aging. Previous reports mainly concerned with laboratory mammals and human tissues indicate an age-related accumulation of lipofuscin. Electron microscopic studies on aging houseflies have reported age-associated changes which include an increase in cellular autophagy and lipofuscin accumulation in nervous tissue, fat body and heart. The present study is concerned with electron microscopic and histochemical examination of the epithelium of the midgut of the housefly, Musca domestica. Special attention is given to the formation of lipofuscin and to the localization of acid phosphatase activity in aging animals.

Tissue was acquired from the midgut of houseflies of known ages, fixed in gluteraldehyde and refixed in osmic acid. Samples were prepared by the method of Gomori for acid phosphatase localization. The preparations were embedded in Maraglas and studied with the Hitachi HUllB-2 transmission electron microscope.
Electron Probe X-Ray Microanalysis of Cardiac Muscle: Progress Report
Authors: Tormey J. McD. , Wheeler-Clark E. S.
Published: June 2020

Myocardial contractility is primarily controlled by the moment to moment concentration of ionized Ca around the myofibrils. This concentration in turn is determined by a large number of factors, including gradients of various electrolytes across cell membranes and the concentrations of Ca in various subcellular compartments. The latter include sarcoplasmic reticulum (SR), mitochondria, binding sites associated with sarcolemmae and T-tubules, and binding sites within the sarcoplasm itself. A central problem in cardiac physiology has been to determine the functional interrelationships among these subcellular compartments.

Electron probe x-ray microanalysis (EPMA) is the method of choice for directly measuring the concentrations within subcellular compartments of cells, and thus offers an unique opportunity to resolve the interpretive uncertainties inherent in alternative methods. Indeed, this method has yielded impressive results when applied by Soralyo et al. to a similar analytical problem in skeletal muscle.
Studies of Ultra-High Speed Silicon Crystal Growth From The Melt By Use of Conventional and High Resolution Transmission Electron Microscopy
Authors: Cullis A. G.
Published: June 2020

Fast melting and solidification of semiconductors by use of Q-switched laser irradiation techniques has provided, during the last few years, a large amount of information on novel high speed crystal growth processes. Under the highest quench rate conditions, the motion of the final solidification interface can be so rapid (many metres per second) that atomic ordering processes are overwhelmed and either defective crystal or even the amorphous solid phase is formed. Most work in this area has been carried out on elemental Si and electron microscopy of solidification structures has played an essential analytical role through both conventional and high resolution imaging studies. The present paper will outline recent progress which has been made in understanding the crystallographic orientation dependence of high-speed growth phenomena.
Rapidly Solidified Microstructures in Eutectic Alloys
Authors: Tanner Lee E. , Jacobson Loren , Gronsky Ron
Published: June 2020

A primary goal of RSP has been to enhance the post-solidification age-hardening behavior of alloys via the extension of solute solubility of their terminal solid solutions. In the case of Al-Be, it was a matter of creating supersaturation of Be in Al since Be solubility is so very low at equilibrium. This approach failed and melt-quenching produced a variety of fine-scale, two-phase microstructures in splats and ribbons. Included were remarkably uniform dispersions of tiny, spherical, incoherent Be particles appearing over a range of compositions spanning the eutectic (Ce=2.5 at% Be) and beyond. The dispersions can be found in hypoeutectic alloys but are restricted to the chill zone in contact with the cold substrate. Fig. 1a,b shows 3-5nm Be particles clustered within the central region of a grain in Al-0.5 at% Be. Further into the bulk of a splat or ribbon the grains have the expected cellular structure of primary Al enclosed by cell walls filled with the small Be particles (Fig. 1c,d).
A Polymer Thin-Film Technique to Study Phase Separation
Authors: Shaffer O.L. , Dimonie V. , El-Aasser M.S. , Vanderhoff J.W.
Published: June 2020

There is a great deal of interest in the morphology of polymers. Polymer systems such as physical blends, copolymers and latexes of the core-shell type have become increasingly important in “designing properties”. of the final polymer. Phase separation examination is an excellent method of studying the morphology in these polymer systems.

Normally phase separation in polymers has been studied by TEM. The standard sample preparation is to embed the solid polymer in epoxy and then microtome. Microtoming can create artifacts such as distortion due to the knife, cutting difficulty with a rubber phase and possible polymer-epoxy interaction. Because of the above mentioned problems a thin film technique has been developed to circumvent the microtoming procedure. A ruthenium tetrox-ide (RUO4) stain was also used to increase contrast.
Microanalysis of Airborne Lead Particulates in an Urban Industrial Environment
Authors: Doern F. E. , Wotton D. L.
Published: June 2020

Introduction

Weston is a small residential neighborhood in the northwest quadrant of the City of Winnipeg (see Figure 1). The community, in addition to being surrounded by industrial activity, is also unusual in having a secondary lead smelter (Canadian Bronze Co. Ltd.) located within its residential area. There are two other secondary lead smelters in Winnipeg, both of which are also located in the northwest of the city. Concern about high levels of lead found in blood of children from Weston School, located some two blocks from Canadian Bronze and adjacent to moderately heavy traffic, prompted a rigorous air- and soil-sampling program. Following this there was considerable public/political debate and ultimately a sod/soil removal program at the school, and from a number of residential properties in the Weston area. The need to identify the lead source(s) came to the forefront again when lead-in-soil at Weston School was found to be approaching the maximum acceptable level (2600 μg/g for lead in urban soil) within twelve months following the “clean-up” operation.
Document Examination Using Scanning Electron Microscopy & X-Ray Spectrometry
Authors: Nolan P. J.
Published: June 2020

This paper reviews the application of scanning electron microscopy and x-ray spectrometry to the examination of questioned documents that have been submitted to the author's laboratory. The use of the SEM is confined to examples where it can provide information unobtainable by alternative methods. This is demonstrated using a variety of examples including paper and printing ink analysis, and the examination of valuable documents, such as stamps. The strategy followed when attempting to determine the sequence of overlapping or intersecting writings is discussed. Special sample preparation techniques are explained and guidelines for optimizing instrumental conditions for different sample types are outlined.
Pyrotechnic Residues in Gunshot Residue Analysis
Authors: Sagara H. M. , Schliebe S. A. , Kong M. C.
Published: June 2020

Particle analysis by scanning electron microscopy with energy-dispersive x- ray analysis is one of the current methods used in crime laboratories to aid law enforcement in identifying individuals who have recently fired or handled a firearm. During the discharge of a firearm, the high pressure caused by the detonation of the cartridge materials forces a portion of the generated gases through leaks in the firing mechanism of the weapon. These gases contain residues of smokeless powder, primer mixture, and contributions from the projectile itself. The condensation of these hot gases form discrete, micrometer-sized particles, which can be collected, along with dry skin cells, salts, and other hand debris, from the hands of a shooter by a simple adhesive lift technique. The examination of the carbon-coated adhesive lifts consist of time consuming systematic searches for high contrast particles of spherical morphology with the characteristic elemental composition of antimony, barium and lead. A detailed list of the elemental compositions which match the criteria for gunshot residue are discussed in the Aerospace report.
In-Line Electron Holography in a Stem Instrument
Authors: Lin J.A. , Cowley J.M.
Published: June 2020

It was suggested earlier that the idea of in-line electron holography, as proposed by Gabor in 1949 could now be implemented by use of a STEM instrument having a cold field emission gun. Reconstruction from holograms by computer methods, in place of the optical techniques suggested by Gabor, was shown to be effective for one-dimensional theoretically derived holograms. We have now applied the method of computerized reconstruction to digitized shadow image holograms recorded in our HB5 STEM instrument which has been modified to facilitate the process.

The shadow image is formed on a phosphor screen in the detector plane. The light produced is amplified by means of an electrostatic image intensifier and viewed with a low-light-level TV camera. The output is digitized and stored by use of a TV-rate frame store and a PDP11/34 computer.
Development of a New 300kv Ultra-High-Resolution/High Performance Analytical TEM (H-9000)
Authors: Fujita H. , Ura K. , Sata H. , Miyauchi K. , Onai T. , Shii K. , Kubozoe M.
Published: June 2020

Higher voltage is advantageous for better imaging resolution, better EELS performance and easier microscopy. Generally it results in a large scaled instrument with many associated problems. In the analytical area, there is a possibility of optimum voltage when a total performance balance is taken in consideration. We have developed a 300 KV TEM for both ultra high resolution and high performance analytical applications in view of these parameters. We have suceeded in making the instrument as compact as possible in order that it may improve the cost/performance ratio. We have taken full advantage of our ultra high voltage microscope experiences.

Fig. 1 is a general view of the instrument. It is only 2.68m high and the same as conventional 200KV instruments. It consists of a 3-stage illumination and a 5-stage imaging lens system. This design allows the orientation matching for the diffraction pattern and TEM image throughout the entire magnification range.
Electron Detectors For Microanalysis and High-Resolution Imaging
Authors: Christou A.
Published: June 2020

Abstract

Presently available electron detectors are reviewed. These detectors are divided into electrostatic analyzers and magnetic or multi-channel analyzers. Imaging detectors also include the SLEEP (Scanning Low Energy Electron Probe) and the LLE detectors (Low Loss Electrons).