bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Microscopy of Silicon Deposits in Foliar Idioblasts of Magnolia Grandiflora
Authors: Postek Michael T.
Published: June 2020

Silicon occurs naturally in plants in the form of its hydrated oxide (SiO2.nH2O) commonly called silica. Silica has been shown to be a necessary element in the normal development of many plants, playing an array of roles including strengthening, protection, and reduction of water loss. Deposition of silica in various portions of the plant body, especially the leaves, may also be viewed as a way for the plant to dispose of any excess silica taken up beyond that necessary for normal metabolism.

Studies of this “opaline” silica have thus far been limited to species of the Cyperaceae and Gramineae known to possess significant quantities of silica. Within the Magnoliaceae, certain “glistening” idioblast cells at the foliar veinlet termini and vein sheaths of Magnolia grandiflora (1) have been suspected to be siliceous in nature.
Electronmicroscopic Mass Determination Without A Densitometer: Quantitative Electron Microscopy Using Photographic Methods
Authors: Lamvik M. K.
Published: June 2020

Zeitler and Bahr showed that the mass of a microscopic object could be determined in the electron microscope, since there is a straightforward relationship between the mass thickness of a point on an object and the transmission of a corresponding point on the electron micrographs. Analysis of such micrographs usually requires specialized equipment for densitometry, but here a simple photographic method will be applied to the determination of mass thickness from electron micrographs.

Polystyrene spheres are convenient objects for mass calibration due to their spherical shape. For a sphere of radius r, the thickness 2z of any point a distance x away from the center of the sphere is given bythus, the sphere is a continuous calibration standard for thicknesses from 0 to 2r. As a convenient substitute for a densitometer, a high contrast film can be used to copy an original.
Scanning Electron Microscopy and Energy Dispersive Analysis Applied to Forensic Science
Authors: Judd G.
Published: June 2020

Analysis of physical evidence in police investigations by electron optical techniques has been performed in several laboratories in recent years. These studies have evolved in stages from exploratory evaluation of the viability of first SEM and then EDA analyses of samples, to extensive programs investigating certain classes of evidence materials, to detailed cataloging of the features and the results of large numbers of individual analyses within a class, to the ultimate test of the techniques, application in criminal investigations. During these studies, the following different general characteristics of the analyses emerged - analyses dependent upon the topography, those dependent upon the composition, and those dependent upon both composition and topography. In the experiences in our investigations (l-3), the number of analyses requiring some information from chemical composition were far greater than originally expected.
Scanning Electron Diffraction: Principles and Techniques
Authors: Maher Dennis M.
Published: June 2020

In this summary the principles and techniques of scanning electron diffraction (SED) in a conventional transmission electron microscope (CTEM) equipped with a scanning attachment will be outlined. For a comprehensive review on this subject see Ref. [l].

Let us assume that this CTEM has been modified so that scanning above and below the specimen are possible. Figure 1 shows a cross-section of such an optical system where scan coils 1 and 2 are used to deflect the incident electron beam and scan coil 3 to deflect the transmitted electrons. For discussion purposes the modes of operation will be subdivided into two classifications, namely undeflected and deflected illumination. For undeflected illumination (i.e. transmission scanning electron diffraction, TSED) the transmitted, scattered-electron distribution is time independent in the sense that all object points are irradiated simultaneously and the illuminating angle is constant.
Quantitative Elemental Analysis of “Transparent” Particles in the Tem
Authors: Sprys J. W. , Short M. A.
Published: June 2020

The quantitative elemental analysis of small particles can be performed in the transmission electron microscope by use of an energy dispersive X-ray detector and multichannel analyzer. As recently suggested by Cliff and Lorimer (1), Equation 1

is used to determine a calibration curve of X-ray intensities relative to silicon for the accurate chemical analysis of thin particles. In this equation, I1 and I2 are the measured characteristic X-ray intensities of the two elements in question, C1 and C2 are the weight fractions and k is a proportionality constant. Absorption, atomic number and fluorescence corrections in transparent particles are assumed to be negligible at an electron accelerating voltage of 100 keV.
In Situ Experiments in the High Voltage Electron Microscope
Authors: Butler E. Paul
Published: June 2020

Cellular decomposition in Ni-60wt%Au

Both cellular and spinodal decomposition into Au-rich and Ni-rich phases occur when this alloy is aged. In situobservations allowed single cell colonies to be studied as they grew through and consumed the spinodally decomposed matrix, and also provided values for the interlamellar spacing S, and growth rate G, at different temperatures. At 415°C cellular growth proceeded at an average rate of 57Å/s (Fig. 1) with S = 855Å and a compositional ratio K of 0.7. Substituting these values in the modified equation for cellular growth as if controlled by cell boundary diffusion, G = KDbδ/S2 with published values of Db and δ=5Å, gave G = 48Å/S, in good agreement with the experimentally observed growth rate.
Rapid Sem-Microprobe Identification of Mineral Inclusions in Drilled Cores
Authors: Feuerbacher D.G. , Cordova M.H.
Published: June 2020

Analysis of micro-inclusions and particulates in core samples is quite important in the geological classification of sedimentary formations as well as in choosing proper drilling fluids, completion systems, and in other oil-field operations. SEM-x-ray microprobe techniques, using energy dispersive detectors, are widely used in mineral analysis, but quantitative analysis is often difficult or time-consuming because of 2 the need for a multi-element standard and sophisticated computer software.

A rapid method of SEM-x-ray micro-analysis of mineral inclusions was investigated. Using freshly-cleaved carbon coated crystals of selected minerals, x-ray spectra were first made of a planar area of each crystal, using the same conditions (see Table 1) each time. The spectra thus obtained were stored on the IBM-type floppy disk by a special MCA datatransfer function (developed by Ortec, Inc.).
Third-Order Aberration Correction in the Sem and Stem
Authors: Parker N. W. , Golladay S. D. , Crewe A. V.
Published: June 2020

The resolution and field of view attainable in electron microscopes is limited by third-order aberrations of the optical system. While considerable effort has been made to determine the effects of these aberrations on the CTEM, little work has been done for the case of the STEM, We have found that one of the advantages of the scanning microscope (both STEM and SEM) is that all third-order aberrations can be eliminated, which is not possible in the CTEM.

Spherical aberration may be cancelled using a non-cylindrically symmetric system of lenses as first suggested by Scherzer. An example of such a system would be the quadrupole-octupole corrector first constructed by Deltrap and currently being applied to a 100 kV STEM by Beck and Crewe. If one wishes to increase the field of view attainable, the remaining seven geometrical aberrations become the limiting factors. These aberrations, in roughly decreasing order of importance, are isotropic and anisotropic coma (S6and S7coefficients), isotropic and anisotropic astigmatism (S4and S5), curvature of field (S3) and isotropic and anisotropic distortion (S1and S2).
Electron Diffraction from Elastically Bent Crystals of Long Chain Compounds
Authors: Dorset Douglas L.
Published: June 2020

Diffraction contrast electron microscopy of microcrystalline long chain lipids at low beam currents reveals flexible bending of these crystals due to forces imposed by the underlying support film. Such bend contours as are illustrated here for microcrystals of cholesteryl nervonate (Fig 1) and glycerol 1,3-dipalmitate (Fig 2) can be indexed by dark field images formed from strongly diffracting beams (1) and can be measured to estimate the crystal radius of curvature (2). In comparison with earlier studies on polyethylene single crystals (3), such measurements indicate lipid crystals to be much more prone to elastic bends than are polymer crystals, although similar details, including edge dislocations, are sometimes evidenced in moire1 fringe patterns (4).
Residual Stacking Fault Contrast in Silicon
Authors: Warren J.B. , Hren J.J.
Published: June 2020

Since the advent of computer techniques used to simulate contrast images of crystal defects, increasing attention has been placed on the interpretation of the fine detail of individual defect images. One fruitful area for computer simulation methods concerns the explanation of residual fringe patterns of stacking faults for two beam conditions in the electron microscope, where g.R = 0,1,2…For this condition, a single stacking fault should be completely invisible, and the presence of residual fringes implies that R is not exactly equal to a perfect lattice vector. Such a modification of R could come about from the strain field resulting from heterogeneous precipitation at the fault plane. Residual fringes have also been produced when either a total or partial dislocation passes through an ordered lattice in Cu-Al alloys.
First H+ Charge-Exchange Images in the Stim.
Authors: Escovitz Wm. H. , R. Fox T. , Levi-Setti R.
Published: June 2020

Charge exchange, the neutralization of ions by electron capture as the ions traverse matter, is a well-known phenomenon of atomic physics which is relevant to ion microscopy. In conventional transmission ion microscopes, the neutral component of the beam after it emerges from the specimen cannot be focused. The scanning transmission ion microscope (STIM) enables the detection of this signal to make images. Experiments with a low-resolution 55 kV STIM indicate that the charge-exchange signal provides a new contrast mechanism to detect extremely small amounts of matter. In an early version of charge-exchange detection (fig. 1), a permanent magnet installed between the specimen and the detector (a channel electron multiplier) sweeps the charged beam component away from the detector and allows only the neutrals to reach it. When the magnet is removed, both charged and neutral particles reach the detector.
Quantitative microanalysis by electron energy-loss spectrometry
Authors: Egerton R.P. , Rossouw C.J. , Whelan M.J.
Published: June 2020

For elements in the first and second rows of the periodic table, microanalysis based on K-shell energy-loss spectra has two major advantages over x-ray emission methods: (1) The K-loss signal remains high, whereas the x-ray production efficiency is less than 10%. (2) The collection efficiency can be better than 30%,since most of the inelastically scattered electrons lie within 5° of the forward direction.

The practical problems are concerned not so much with the relatively low intensity of K-shell losses as with the background contribution to the spectrum due to valence-electron excitation. The latter can be corrected for by extrapolation of the spectrum preceding the K-edge but this procedure becomes inaccurate in the case of a low signal-to-noise ratio or a large range of extrapolation. Therefore it is desirable to measure the loss electrons over as small an energy window as possible, consistent with an adequate K-loss signal/noise ratio.
Use of LaB6for a High Quality, Small Energy Spread Beam in an Electron Velocity Spectrometer
Authors: Batson P. E. , Chen C. H. , Silcox J.
Published: June 2020

Electron energy loss experiments combined with microscopy have proven to be a valuable tool for the exploration of the structure of electronic excitations in materials. These types of excitations, however, are difficult to measure because of their small intensity. In a usual situation, the filament of the microscope is run at a very high temperature in order to present as much intensity as possible at the specimen. This results in a degradation of the ultimate energy resolution of the instrument due to thermal broadening of the electron beam.

We report here observations and measurements on a new LaB filament in a microscope-velocity spectrometer system. We have found that, in general, we may retain a good energy resolution with intensities comparable to or greater than those available with the very high temperature tungsten filament. We have also explored the energy distribution of this filament.
The use of Direct Phasing Methods for Single Crystal Electron Diffraction Data. I. Methylene Subcells
Authors: Dorset D. L. , Hauptman H. A.
Published: June 2020

The significant impediment to the use of electron diffraction data for crystal structure analysis is, of course, the perturbation of n-beam dynamical effects. In more severe cases this dynamical perturbation gives an intensity distribution in the diffraction pattern which is not directly related to the underlying crystal structure, thus making the determination of complex structures nearly impossible by this technique.

However, as was experimentally established in Vainshtein's laboratory and is theoretically predicted, the diffraction of electrons from thin mosaic crystals composed of light atoms is in accord with kinematical theory to a good first approximation and, furthermore, ab initiocrystal structure analyses are tractable viastandard crystallographic phase determination. To date the few electronographic determinations of unknown organic structures have used either trial and error or Patterson techniques.
An Image Intensifier and Polaroid Camera for the Tem
Authors: Turnbull T. P. , Fullam Ernest F. , Shaffer Charles
Published: June 2020

Ever since the transmission electron microscope was invented and introduced into the scientific laboratory as a working tool, there have been two features desired by most microscopists which have never been completely fulfilled by the manufacturers of the instrument at reasonable cost. The first, adequate intensity at all magnifications and sufficient illumination of the screen when viewing heat-sensitive specimens. A second most desired feature is instant photography of what is being observed on the fluorescent screen. These two desired features are now available by adapting on the shelf devices to the TEM.

The first device is for intensifying the image normally viewed on the fluorescent screen for critical focusing, contrast enhancement for specimen scanning without burning up the sample by excessive electron bombardment or by increasing specimen contamination. A second device is a method of simple outside the column photography without image grain or distortion and without alteration to the normal operation of the electron microscope.
Electron Beam Damage at Low Temperatures
Authors: Ramamurti K. , Crewe A. V. , Isaacson M. S.
Published: June 2020

While significant advances have been made recently in obtaining specimen detail at near atomic resolution, electron beam damage continues to be a limiting factor for biological specimens. The techniques developed to circumvent this limitation depend upon keeping the damage to a minimum. A complementary approach that reduces the damage itself would be of considerable advantage. We would like to discuss the implications of a cooled specimen in the light of low temperature measurements reported so far.

The specimen in the microscope can be characterized by its physical and chemical states, and any changes due to electron beam damage can be monitored by changes in mass, electron diffraction pattern and energy-loss spectrum. Most of the low temperature measurements reported so far (see Ref.
Tem and Stem Microanalysis
Authors: Russ J. C.
Published: June 2020

The technique widely know as “Analytical Electron Microscopy” is now being applied in a great variety of scientific and technical fields. It combines the examination of specimen morphology and structure with elemental analysis.

The characteristic X-rays generated in the sample can be used to obtain elemental analysis of the region of the sample being hit by the electrons. The traditional electron probe microanalyzer used this method with wavelength-dispersive diffracting spectrometers . The advent of the SEM with its much lower electron beam currents (in order to achieve smaller beams for high resolution images) and rough samples (which do not lie on the focusing circle of a wavelength-dispersive spectrometer) nurtured the development of the energy-dispersive X-ray analyzer. The further use of this new method with the TEM and STEM has opened up entire new areas of application.

As the name implies, the energy-dispersive spectrometer measures X-ray energy directly producing a spectrum of counts versus energy. The combination of higher geometrical and detector efficiency means that ED detectors can give count rates up to several hundred times greater than the WD spectrometer.
Progress in Aberration Correction in the Stem
Authors: Beck V. , Crewe A. V.
Published: June 2020

A STEM which includes a corrector for primary spherical aberration has been built and is being put into1operation. The microscope is expected to achieve a resolution of 1 Å at 50 keV. This high resolution is possible because of the correction of spherical aberration.

The corrector and its operation have been described in detail elsewhere. Briefly, the corrector consists of non-cylindrically symmetric elements, four quadrupoles and three octupoles, which produce a negative primary spherical aberration. This cancels the positive spherical aberration which arises from the cylindrically symmetric objective lens as a result of Scherzer's theorem.

The corrector and objective are physically separated by 23 cm. This separation causes secondary spherical aberration (C5= 18 cm) and it is this aberration which limits the microscope's resolution.
Precipitation in Lunar Plagioclase Annealed for 10 Million-500 Million Years
Authors: Nord G. L.
Published: June 2020

Inclusions in minerals, expecially if formed by isochemical precipitation, are useful indicators of thermal history as well as the extent of solid solution one mineral phase has with another. Because of the very slow diffusion rates in silicates, many geologically useful precipitation reactions are not amenable to laboratory experiments but must be characterized by studying natural materials that have varied thermal histories. Certainly one of the longest natural annealing experiments was the cooling of the original lunar crust. Plagioclase is the most abundant mineral in the lunar crust and commonly contains inclusions of other phases such as pyroxenes, Ni-Fe alloys, ilmenite, and silica polymorphs. Only rarely, however, can these minor phases be shown to be the result of precipitation rather than inclusion during crystallization, as they occur in rocks that have undergone complex mechanical and thermal cycling as well as recrystallization as a result of repeated meteoroid impacts. An electron-optical study was therefore made of precipitates in calcic plagioclase (CaAl2Si2O8) in Apollo Rock 76535. This sample was chosen because it had experienced a long continuous cooling (10 million-500 million years) before it was excavated to the lunar surface.
The Detection and Identification of Asbestos and Asbestiform Minerals in Talc
Authors: Stanley Harold D.
Published: June 2020

Concern with the health hazards associated with the presence of chrysotile asbestos and/or the asbestiform minerals in talc has prompted widespread investigation of methods of analysis which would be consistent with good analytical practicies. Of all the currently available techniques examined and evaluated, the two most reliable have been found by us to be Step Scanning X-ray Diffraction and Transmission Electron Microscopy, (TEM), with Selected Area Electron Diffraction, (SAED). The Step Scanning X-ray Diffraction technique allows quantitative detection and identification of tremolite and the asbestiform minerals down to 0.1% by weight. In the absence of chlorite it can detect and quantitatively determine chrysotile asbestos at the 0.5% level. Chlorite, however, is often associated with talc ore bodies. When present, chlorite will mask most of the main X-ray diffraction peaks of chrysotile. The X-ray diffraction technique cannot distinguish between fibrous and non-fibrous forms of the asbestiform minerals.
Scanning Electron Microscope Study of the Effect of Structure on the Liquefaction of New Mexico Coals
Authors: Murr L.E. , Wongwiwat K.
Published: June 2020

While it is well known that certain pulverized coals can be liquified above ground in controlled conditions of solvent, pressure, and temperature; liquefaction of other coals is difficult to achieve. In the face of an increased demand for energy, and on considering the abundant supply of coal in parts of the United States, innovative research has been initiated to attempt to liquify coal in-situ using well-bore techniques which are essentially the same as those employed for petroleum production. In attempting in-situ liquefaction, the coal reaction face is essentially unpulverized, and liquefaction generally requires high temperatures (>400°C) and pressures (>2000 psi).

The liquefaction processes involved in the hydrogenation or solution mining of coal are dependent upon both physical and chemical properties involving the structure and composition (including mineral impurities and trace elements) of the coal, the solvent, the surface area exposed - including particle size, homogeneity, cracks, pores, etc. - pressure, temperature, and catalyst. All of these properties in a consonant manner will control the rate and extent of liquefaction.
Antiphase Boundaries in Low Temperature Phases of Gd2 (M0O4)3, LaAlO3 & SrTiO3
Authors: Yagi K. , Yamamoto N. , Honjo G.
Published: June 2020

From space group relationships of structures of high and low temperatures phases of Gd2(Mo0i,)3 (1), LaA1O3 and SrTiO3, antiphase boundaries (APBs) are expected to exist in the low temperature phases of these substances in addition to domain boundaries due to slight distortions of the lattices. The APBs may be considered to be formed due to the difference in phases of condensing soft modes from place to place.

1. Gd2(MoO4)3. In addition to antiparallel ferroelectric domain boundaries which show so called 6-type asymmetric fringes, a-type symmetric fringes due to APBs were observed below the transition point 160°C (Fig. 1) (2). Since the unit cell of the low temperature phase is two times as large as that of the high temperature phase APB should not have been seen under excitations of fundamental reflections such as (2h O O) and (O 2k O), if the displacement vector at the APB were R茸 = (a+b). The fact that it is seen in Fig. 1 means that there is an additional displacement AR due to lattice relaxation at the boundary.
Interactions Between Al and Cr Thin Films
Authors: Anderson R. M. , Reith T. M. , Sullivan M. J. , Brandis E. K.
Published: June 2020

Thin films of aluminum or aluminum-silicon can be used in conjunction with thin films of chromium in integrated electronic circuits. For some applications, these films exhibit undesirable reactions; in particular, intermetallic formation below 500 C must be inhibited or prevented. The Al films, being the principal current carriers in interconnective metal applications, are usually much thicker than the Cr; so one might expect Al-rich intermetallics to form when the processing temperature goes out of control. Unfortunately, the JCPDS and the literature do not contain enough data on the Al-rich phases CrAl7 and Cr2Al11, and the determination of these data was a secondary aim of this work.

To define a matrix of Cr-Al diffusion couples, Cr-Al films were deposited with two sets of variables: Al or Al-Si, and broken vacuum or single pumpdown. All films were deposited on 2-1/4-inch thermally oxidized Si substrates. A 500-Å layer of Cr was deposited at 120 Å/min on substrates at room temperature, in a vacuum system that had been pumped to 2 x 10-6 Torr. Then, with or without vacuum break, a 1000-Å layer of Al or Al-Si was deposited at 35 Å/s, with the substrates still at room temperature.
Observation of Gas Bubbles in Vapor-Deposited Gold Films
Authors: Lloyd J. R. , Nakahara S.
Published: June 2020

Voids or gas hubbies have been observed in sputtered and evaporated gold films, following post deposition annealing. Small voids have also been observed in gold films after electromigration (EM). AS few voids are visible before annealing or prior to EM, it was concluded that these processes are responsible for the principal mechanism for void formation. We have made a further study on the formation of voids or gas bubbles in as-deposited as well as annealed gold films which are prepared by vapor deposition. It is demonstrated that a large number of voids (< 50 Å) are, in fact, present in gold films prior to annealing or EM.

Single-crystal gold films were grown epitaxially by vapor deposition onto KC1 substrates held at 250°C in an ion-pump vacuum of 1 x 10-5 Torr. In order to obtain a variation in deposition rate within a single sample, deposits were made through a mask separated from the substrate, resulting in significant shadowing.
The Structure of Ion-Deposited Crystalline Carbon Films
Authors: Joy D. C. , Spencer E. G. , Schmidt P. H. , Sansalone F. J.
Published: June 2020

Polycrystalline carbon films deposited by an ion source were first studied by Aisenberg and Chabot. Because of the problems they encountered in characterizing these films we have examined similar films made in an apparatus of the type shown in Fig. 1. Samples were deposited on to substrates of NaCl, KC1 or silicon in thicknesses up to 2 μm. Prior to examination in the TEM, the films were dissolved from their substrate material and mounted on grids. The films were highly insulating (∼lO12 ohm cm), optically clear and totally resistant to attack by all common solvents. From ellipsometric measurements the index of refraction was found to be ∼2. Ion backscattering and Auger studies showed the samples to be pure carbon except for the presence of a few percent of the carrier gas (argon, krypton, etc.).

Figure 2 shows a micrograph typical of such a film. Crystallites varying in size up to a maximum of a few microns are found randomly distributed over the sample. In general the morphology of the crystals is typical of a cubic symmetry, with a predominance of 90° edges. As the film thickness increases there is a tendency for existing crystals to act as substrates for new crystals.
Direct Observations of the Growth of Sputtered Silver on Substrates of Graphite and Muscovite MICA
Authors: Maa J. S. , Lee J. I. , Hutchinson Thomas E.
Published: June 2020

The nucleation and growth of sputtered thin films are controlled by several important factors such as nucleus mobility, substrate surface defects, substrate/ overgrowth chemical interaction, and residual gasses, which depend upon the properties of substrate-overgrowth materials and/or the deposition conditions. The effects of nucleus mobility and substrate surface defects on the nucleation and growth of in situ ion beam sputtered thin silver films have been investigated in detail using in situ electron microscopy. Silver has been sputter deposited on the basal plane of single crystal graphite substrate at temperatures ranging from 350°C to 500°C. The results obtained show that the deposition process in the case of silver on graphite is controlled by the nucleus mobility on the substrate surface. The silver islands with sizes of 20Å to 100Å at the early stage of growth are highly mobile on the graphite substrate. The migration of silver islands from one position to another occurs in a very short period of time and the distance of the island migration varies from less than 100Å to several hundred angstroms, as shown in Figure la and lb.
Direct Observation of the Growth of Sputtered Gold Films on (111) Silicon Substrates
Authors: Lee J. I. , Maa J. S. , Hutchinson Thomas E.
Published: June 2020

The study of in situ Ion beam sputtering of gold on substrates of single crystal silicon using well controlled ultrahigh vacuum deposition system shows that substrate/overgrowth interactions involving alloying and interdiffusion greatly influence the growth and structure of sputtered thin gold films.

Gold was sputter deposited on substrates of single crystal at temperatures ranging from 23°C to 500°C and a deposition rate of 15Å/min in vacuum of 2x10-8 torr. The growth and structure of the deposits shows large differences in two substrate temperature regions, the low temperature regions below 200°C and the high temperature regions above 200°C. At low substrate temperatures below 200°C, an amorphous film is first formed as shown in Figure la and followed by the growth of two dimensional polycrystalline gold islands on the newly formed amorphous layer as shown in Figure lb. At high substrate temperatures above 200°C, a liquid alloy of Au-Si and polycrystalline silicon rich regions are formed on the substrate as shown in Figure 2a. The liquid alloy of Au-Si and polycrystalline silicon rich regions are phase transformed to the polycrystalline gold and silicon rich regions during cooling to room temperature as shown in Figure 2b.
Lattice Imaging Analysis of the Solid State β-α Ot Transformation in CVD Grown SiC
Authors: Shinozaki S. , Kinsman K. R.
Published: June 2020

In SiC anisotropic α phase morphologies and planar defect dominated microstructures of the close-packed α (Hexagonal) and β (FCC) phases, and their coherent crystallographic relationship to one another in mixtures, have been observed. These characteristics indicate a fundamental mechanistic similarity to other FCC-HCP solid state transformations in a host of metallic alloy systems. In these metallic systems (1,2) as well as in SiC (3), it is apparent that the key transformation feature is rearrangement of close packed planes by nucleation and propagation of stacking faults. In this paper, we present support for this view, using chemical vapor deposited (CVD) SiC as a basis material.

The deposition condition used encourages large grains, a textured arrangement of the grains, and promotes profuse twinning along {111} β aligned mostly along the direction of growth (Fig. 1). X-ray diffraction analysis indicates the bulk sample is β phase. Transmission electron microscopy and selected area electron diffraction (SAD) of a single grain (Fig. 2) reaffirm that the as-grown structure is comprised of β phase with twins and stacking faults.
Specialized Junctions of the Intercalated Disc of the Active and Hibernating Bat Heart
Authors: Hagopian Martin
Published: June 2020

Active bats, Myotis lucifugus, were caught in October, and hibernating bats were caught in January from their natural habitat. Left ventricles were fixed in 6.25% cacodylate buffered gluturaldehyde, washed in buffer, and postfixed in 1% osmium tetroxide. Some tissue in each group was stained en bloc with uranyl acetate, dehydrated, and embedded in Araldite or Epon.

The muscle cells of the bat heart are approximately cylindrical in shape and are connected with one another end-to-end at the intercalated discs. Occasionally the cardiocytes are connected along the lateral surfaces. In general the intercalated disc is composed of transverse and longitudinal segments.
Unique Photoreceptor in Tornaria Larvae (Hemichordata: Enteropneusta)
Authors: Woollacott Robert M. , Brandenburger Jean L. , Eakin Richard M.
Published: June 2020

To extend a survey of photoreceptors in the animal kingdom, initiated by one of us (RME), we examined electron microscopically the paired eyespots on tornariae of two species of hemichordates. Some specimens (species unknown) were collected from the plankton near the Santa Catalina Marine Biological Laboratory, Santa Catalina Island, California; other tornariae were reared from eggs of Ptychodera flava at the University of Hawaii.

The tornarian ocellus studied by us is a single-layered, ectodermal cup open to the exterior but without a lens, contrary to the description of light microscopists (see 1). Two types of cells form the wall of the eyecup: sensory and pigmented.
Ultrastructural Findings of a Rare Myxoid Tumor in a Case of Scleroderma
Authors: Cowley L. H. , Turk L. L. , Grafton W. D. , Jamison R. M.
Published: June 2020

Scleroderma is a skin disease of unknown cause. The systemic form frequently begins peripherally, producing atrophy of the underlying fat and a thickening of the dermis. Tumors associated with scleroderma are distinctly uncommon. Only one other similar case has been alluded to in the literature.

This patient presented with tumors 4mm to 3cm in size over the fingers and toes. The tumors were tense to touch although readily depressable without pain. A large tumor was removed surgically from the right index finger. Hematoxylin and eosin staining of paraffin sections revealed a normal appearing epidermis with slight thickening of the papillary dermis. The reticular dermis was edematous and contained sparse amounts of collagen with some fibroblast-like cells which were spindle-shaped and stellate. Histochemical stains showed a large quantity of amorphous material that was PAS positive, diastase-resistant and alcian blue positive at pH 4.
Collagenoma: A Hitherto Unreported Soft Tissue Tumor
Authors: Allegra S.R.
Published: June 2020

The purpose of this paper is to describe a soft tissue tumor whose histological characteristics have not hitherto been described and for which the term “Collagenoma” is proposed. The tumor was characterized by growth of immature, glycogen laden, fibroblastic cells displaying evidence of simultaneous intracytoplasmic collagen synthesis and pericellular collagenolysis. The latter resulted in the formation of characteristic clear pericellular spaces giving the tissue an appearance somewhat reminiscent of fibrous cartilage as, for instance, the connective tissue of the temporo-mandibular joint. However cartilage was not produced by the tumor cells which were solely engaged in intense production of a remarkably uniform fibrocollagenous matrix.
Morphogenesis of a Virus Isolated from a Human with Myelomonocytic Leukemia
Authors: Jamison Richard M.
Published: June 2020

A virus has been isolated in tissue culture by co-cultivation in vitro of peripheral leukocytes from a leukemic donor with monkey kidney cells. This virus contains ribonucleic acid, its density is similar to that of members of the oncorna virus group, and its replication is inhibited by Actinomycin D; it is presumably a human oncornavirus. The virus has been detected by electron microscopy both in the peripheral leukocytes of the leukemic donor and in tissue cultures of the continuous monkey kidney cell line originally co-cultivated with these peripheral leukocytes. Plasma from the leukemic donor reacts in indirect immunofluorescence tests with the infected tissue cultures but not with non-infected controls. More recently, infection of a continuous human cell line (FL) has been detected by electron microscopy. Appropriate cell controls are negative.
Spermatogenesis in the Dragonfly with Particular Reference to the Cytoplasmic Organelles
Authors: Sekhon Sant S.
Published: June 2020

Although there have been numerous studies concerning the morphogenetic changes accompanying the maturation of insect sperm, only a few deal with the sperm differentiation in the dragonflies. In two recent electron microscopic studies Kessel, has comprehensively treated the erlationship of microtubules to the nucleus and mid-piece structures during spermiogenesis in the dragonfly. The purpose of this study is to follow the sequential nuclear and cytoplasmic changes which accompany the differentiation of spermatogonium into a mature sperm during spermatogenesis in the dragonfly (Aeschna sp.).

The dragonfly spermatogonia are characterized by large round nuclei. Loosely organized chromatin is usually unevenly distributed within the spermatogonial nuclei. The scant cytoplasm surrounding the nucleus contains mitochondria, the Golgi apparatus, elements of endoplasmic reticulum and numerous ribosomes (Fig. 1).
Binucleate Spermiogenesis in the Mouse
Authors: Wolosewick John J.
Published: June 2020

Classically, the male germinal epithelium is depicted as synchronously developing uninucleate spermatids conjoined by intercellular bridges. Recently, binucleate and multinucleate spermatids from human and mouse testis have been reported. The present paper describes certain developmental events in one type of binucleate spermatid in the seminiferous epithelium of the mouse.

Testes of adult mice (ABP Jax) were removed from the animals after cervical dislocation and placed into 2.5% glutaraldehyde/Millonig's phosphate buffer (pH 7.2). Testicular capsules were gently split and separated, exposing the tubules. After 15 minutes the tissue was carefully cut into cubes (approx. 1mm), fixed for an additional 45 minutes and processed for electron microscopy.
Structures Resembling Striated Rootlets in Oocytes
Authors: Ernst Valerie V.
Published: June 2020

During the earliest stage of oocyte development in the limpet, Acmea scutum, Golgi complexes are small, few and randomly dispersed in the cytoplasm. As growth proceeds, the Golgi complexes increase in size and number and migrate to the periphery of the cell. At this time, fibrous structures resembling striated rootlets occur associated with the Golgi complexes. Only one fibrous structure appears to be associated with a Golgi complex.

The fibers are periodically cross banded with an average of 4 dense fibrils and 6 lighter fibrils per period (Fig. 1). The cross fibrils have a center to center spacing of about 7 run which appears to be the same as that of the striated rootlets of the gill cilia in this animal.
Effects of Chorionic Gonadotropic Hormone (HCG) on the Ultrastructure of Normal and Grafted Ovaries
Authors: Baccarini I. M.
Published: June 2020

Human chorionic gonadotrophic hormone (HCG) has a luteotropic effect which induces luteinization of the granulosa cells. A large concentration of HCG in a culture of granulosa cells induces luteinization and increases the levels of progesterone secreted by each of the granulosa cells. The present report describes the submicroscopic structure of the granulosalutein cells under long term daily doses of human chorionic gonadotropic hormone.

The ovaries from a group of 10 mice 30 days old were removed, and a small piece of one ovary was placed into the spleen. Another group of 5 mice of the same age was used for a control. Human chorionic gonadotropic hormone (28 Ul) was injected daily subcutaneously. The vagina was opened on the fourth day after the first injection.
Ultra-High Voltage Electron Microscopy (1-3 MeV) of Biological Macromolecules
Authors: Massover William H.
Published: June 2020

Important difficulties persist for high resolution (= pauci-atomic) electron microscopy of biological macromolecules in terms of obtaining (a) higher effective resolution, (b) decreased specimen damage induced by the electron beam irradiation, and (c) adequate image contrast without the use of extraneous contrasting agents. Electron microscopy at elevated accelerating tensions can largely provide a solution to some of these very problems. Use of a 46μm diameter beam stop (at the level of the objective aperture) for 1000 kV, and of a 23μm diameter beam stop for 3000 kV, produces very high contrast dark field imaging conditions that also retain a higher effective resolution than do the previous beam stop methods developed by Dupouy et al.
Mass and Mass Loss Measurements on DNA and fd Phage
Authors: Wall Joseph
Published: June 2020

Mass measurements can be done with the scanning transmission electron microscope in a manner similar to the densitometry of conventional microscope plates. Since the measurements are made directly on the microscope output signal, however, there are none of the non-linearities associated with film. The two signals (proportional to normalized elastically and inelastically scattered currents) are recorded directly on digital tape for analysis.

Mass can be determined from the scattering data using atomic scattering cross-sections and assuming the cross-section of an object is the sum of the individual atomic cross-sections. Since the elastic and inelastic cross-sections have different dependence on atomic number, it also is possible to estimate the average Z of the object being measured. These calculations are performed using a Nova 800 computer system which is interfaced directly to the microscope.
Head Size and DNA Content in Bacteriophage T4
Authors: Eiserling Fred , Doermann A. H. , Boehner Linde
Published: June 2020

The control of form or shape inheritance can be approached by studying the morphogenesis of bacterial viruses. Shape variants of bacteriophage T4 with altered protein shell (capsid) size and nucleic acid (DNA) content have been found by electron microscopy, and a mutant (E920g in gene 66) controlling head size has been described. This mutant produces short-headed particles which contain 2/3 the normal DNA content and which are non-viable when only one particle infects a cell (Fig. 1).

We report here the isolation of a new mutant (191c) which also appears to be in gene 66 but at a site distinct from E920g. The most striking phenotype of the mutant is the production of about 10% of the phage yield as “giant” virus particles, from 3 to 8 times longer than normal phage (Fig. 2).
The Structure and Arrangement of Pores in Plant Cell Nuclei
Authors: Wardrop A. B. , Thair B. W.
Published: June 2020

Evidence for the presence of ribonucleoprotein in components of nuclear annuli and pores has been reviewed by Franke & Falk (1970). The problem of the structure of nuclear pores revolves around the question as to whether the arrangement of particles in the pore changes with time or whether the arrangement is constant. Thus Roberts & Northcote (1970) have concluded that particles in the pores are arranged in three tiers of eight bordering the pores and from the central tier a central particle is suspended by a series of radially arranged fibrils. A somewhat similar model has been proposed by Franke & Scheer (1970).
Stereo Electron Microscopy and Problems of Interpretation
Authors: Steere Russell L.
Published: June 2020

The need for and value of a goniometer stage and stereo electron microscopy to obtain maximum information from preshadowed carbon replicas of frozen biological specimens has already been documented. Now it is important that one be forewarned of the possibility of misinterpretation of the morphology of an object if only a single electron micrograph or a single stereo pair is used for interpretation.

Surface replicas of the outer surface of frozen begonia petals were prepared in the usual manner. The large pieces of cleaned replica were lifted onto uncoated 75 mesh grids and examined in the JEM 100-B electron microscope with goniometer stage.
Silicon Tetrachloride Synthesis from Rice Hulls: Transmission and Scanning Electron Microscope Study
Authors: Thomas Richard S. , Basu Prabir K. , Jones Francis T.
Published: June 2020

Silicon tetrachloride, used in industry for the production of highest purity silicon and silica, is customarily manufactured from silica-sand and charcoal.

SiCl4 can also be made from rice hulls, which contain up to 20 percent silica and only traces of other mineral matter. Hulls, after carbonization, actually prove superior as a starting material since they react at lower temperature. This use of rice hulls may offer a new, profitable solution for a rice mill byproduct disposal problem.

In studies of the reaction kinetics with carbonized hulls, conversion of SiO2 to SiCl4 was found to proceed within a few minutes to a constant, limited yield which depended reproducibly on the ambient temperature of the reactor. See Fig. 1. This suggested that physical or chemical heterogeneity of the silica in the hull structure might be involved.
Nature of the So-Called Fibrillar Component in the Segregated Nucleolus
Authors: Unuma T. , Senda R. , Muramatsu M.
Published: June 2020

Actinomycin D, selectively blocks DNA-dependent RNA synthesis, causes marked morphological changes of the nucleolus. One of the most prominent changes is the segregation of the nucleolar components. The granular component is redistributed and separated from the other components of the nucleolus. The term nucleolar segregation has been used to designate the separation of the granular and fibrillar components. In the present study, the nucleolus was segregated into two distinct zones, namely the granular and the so-called fibrillar component (Fig. 1). The purpose of this study is to present the evidences of protelnous nature of the so-called fibrillar component in the segregated nucleolus by morphological, biochemical and enzymatic digestion studies.
Cytopathology of Coxsackievirus B3 Infection in Newborn Mouse Pancreas
Authors: Harrison Alyne K. , Bauer Sally P. , Murphy Frederick A.
Published: June 2020

Of the infectious agents suspected of causing acute pancreatitis in man, the group B Coxsackieviruses have long been regarded the prime candidates. Histopathological studies of these viruses in mice have shown extensive damage to acinar cells while ducts and islets were spared. However, recent evidence Indicates that particular Coxsackievirus B types may affect acinar cells whereas others may attack endocrine cells. In the present study, Coxsackievirus B3 was used to elicit a necrotizing pancreatitis in newborn mice which involved both the endocrine and exocrine portions of the gland.

Litters of Swiss mice (ICR strain), less than 12 hours old, were inoculated intraperitoneally with 0.02 ml. of undiluted stock virus suspension (Coxsackievirus B3, Nancy prototype strain).
A Freeze-Fracture Technique for Examining Human Stratum Corneum
Authors: Hannon Daniel P.
Published: June 2020

Human stratum corneum is a difficult tissue to process for electron microscopic examination. Most of the difficulty is due to the inability of the chemical fixative to adequately preserve all of the constituents of this tissue. As a result, during sectioning, breaks occur between cells creating voids which preclude any studies of these areas. Also, because the fixative is usually in an aqueous medium, studies of hydrated or dehydrated states are impossible. However, these problems can be overcome by using an alternative method of sample preparation, freeze-fracture electron microscopy.

Samples of human skin both untreated and soaked for 20 minutes in 20% glycerin were cut into strips 1 mm wide by 2 mm long and placed in specially made copper discs with a 1 mm deep central cup. Freezing was accomplished by immersion in liquid Freon 22.
High Resolution Shadowing of DNA
Authors: Abermann R. , Salpeter M. M.
Published: June 2020

High resolution shadowing by electron beam evaporation was used to visualize DNA molecules. Its applicability to the study of macromolecules at this resolution level was previously demonstrated on monomeric and dimeric tRNA particles.

To utilize the potential of the high resolution shadowing for DNA, a mounting procedure was employed which provided a smooth substrate to which the naked molecules could be bound. This consisted of a two step process, modified from Kleinschmidt Lang, and Harford and Beer. When a 50μl droplet of cytochrome c (20 μg/ml in 0.2M Na acetate at pH 5) was allowed to stand on teflon for 20 minutes, a monolayer of protein formed on its surface. The film was picked up onto carbon coated grids, washed in ethanol and air dried. As test specimen, we used DNA from SV4O. The protein coated grids were floated for 30 minutes on buffer droplets containing 0.1-0.5 μg DNA/ml 10-3SSC and the molecules were bound to the protein monolayers by diffusion. Grids were then washed successively in 50% and absolute ethanol and air dried.