bluuebunny/crossref_metadata_2025 huggingface dataset:
Elimination of Substrate Scattering in Electron Diffraction
Authors: Melvin Cruse
Published: June 2020

Relative intensities of single crystalline electron diffraction spots can be calculated using n-beam dynamical electron diffraction theory. The scattering matrix formulation developed by Sturkey has been applied in this laboratory to calculate the relative intensities of 42 simultaneously diffracted beams from thin gold platelets. The calculations assume normal incidence, parallel entrance and exit surfaces of the crystal, and crystal thickness t. These assumptions severly restrict the experimental techniques which may be used to measure intensities. A suitable technique must hold the crystal normal to the incident beam, allow thickness measurements, and prevent bending. These rather stringent conditions are satisfied by mounting the microcrystal on a substrate. However, a substrate scatters the electron beam and alters the relative intensities being measured. To eliminate substrate scattering and to satisfy most of the above requirements the micro-crystals were studied through holes in the substrate.
Some Current and Future Trends of High Voltage Transmission Electron Microscopy
Authors: Thomas Gareth
Published: June 2020

The Optimum Voltages for Electron Microscopy – The advantages of high voltage electron microscopy are now well established, and many applications, such as use of environmental cells both in metallurgy and biology, are now possible. However recent experiments at Toulouse indicate that except for light elements, there is no appreciable gain in transmission for a given resolution level as the energy is increased above 1 MeV (see Fig. 1). These results are not as optimistic as theory might indicate. Special effects such as critical voltages above 1 MeV are of interest, but knock-on radiation damage imposes limitations on many applications. Thus it would appear that 1 MeV is a reasonable upper limit for most applications in materials science.
Contrast Considerations in Environmental Cells
Authors: Sellar J. R.
Published: June 2020

To study chemical reactions in situ and observe biological specimens in the hydrated state, it is necessary to isolate the specimen from the vacuum of the electron microscope by means of a cell. Figure 1 represents such a cell in a conventional transmission electron microscope (CTEM) with apertures or windows A, specimen mounting B, and specimen T. O labels the objective lens, L the cell gas, and S is the width of the layer of gas.

Calculations have been carried out involving the contrast available when thick specimens are imaged or an environmental cell is used at 1000 keV. For the limitations considered, including multiple scattering, chromatic aberration and the effects of various geometrical configurations, it appears that, in the absence of noise effects due to loss of intensity, multiple scattering causes the largest disc of confusion.
Loop and Void Formation in Copper During High Voltage Electron Microscope Irradiation
Authors: Kenik E. A. , Mitchell T. E.
Published: June 2020

The formation of dislocation loops and voids under neutron, ion, and electron irradiation is well documented. Since irradiation produces Frenkel pairs, the presence of biased interstitial sinks is required for void formation to procede. It is generally accepted that dislocations, generated either by cold-work or irradiation, act as the preferential sinks.

During irradiation in the high voltage electron microscope, both interstitials and vacancies are lost to foil surfaces and corresponding denuded zones are set up. As a result of image forces, dislocation loops formed upon irradiation tend to unfault and glide out of the foil. Thus, below a given thickness, the foil is unable to maintain a sufficiently high dislocation density to support void nucleation and growth.
The Precipitation of Si in AlCuSi Thin Films
Authors: Anderson R. M.
Published: June 2020

Aluminum-copper-silicon thin films have been considered as an interconnection metallurgy for integrated circuit applications. Various schemes have been proposed to incorporate small percent-ages of silicon into films that typically contain two to five percent copper. We undertook a study of the total effect of silicon on the aluminum copper film as revealed by transmission electron microscopy, scanning electron microscopy, x-ray diffraction and ion microprobe techniques as a function of the various deposition methods.

X-ray investigations noted a change in solid solution concentration as a function of Si content before and after heat-treatment. The amount of solid solution in the Al increased with heat-treatment for films with ≥2% silicon and decreased for films <2% silicon.
Morphology of Polyoxymethylene Crystals Grown Inside Irradiated Tetroxane and Pentoxane Crystals
Authors: Reneker D.H. , Colson J.P.
Published: June 2020

X-ray diffraction studies of the polyoxymethylene crystals grown inside Tetroxane and pentoxane crystals showed that the polymer molecules form in a specific way with respect to the monomer crystals. Specific morphological features of polyoxymethylene crystals grown inside irradiated trioxane crystals were reported by the authors. Morphological investigations are presently being extended to the polymer crystals formed inside crystals of the higher cyclic oligomers, tetroxane and pentoxane, in an effort to elucidate the important features of this so called solid state polymerization reaction.

Samples of tetroxane and pentoxane were prepared and irradiated with alpha particles in the same manner as described.
Carbon Support Films for High Resolution Electron Microscopy
Authors: Langmore J. , Wall J. , Isaacson M. , Crewe A. V.
Published: June 2020

The observation of single atoms and unstained biological molecules in the high resolution electron microscope depends upon the ability to discriminate between the image of the specimen and that of the support film used. This depends upon three characteristics of the film. The quantum noise in the image is equal to the square root of the number of electrons collected which have been scattered from the fi1m. Another type of noise, the “structural” noise, is caused by fluctuations in the film thickness. The third, “high Z” noise, is caused by extraneous atoms of high atomic number present on the film. In order to find the best carbon substrate for our specimens, we have studied the structure of thin (∼5-50 Å) carbon films evaporated onto various crystalline substrates.
Thin Carbon Film Areas Produced under Controlled Conditions
Authors: Rizk Nabil , Bendet Irwin
Published: June 2020

The need for increasingly thin films to attain the ultimate in high resolution electron microscopy has seen the development of carbon substrates for the support of biological macromolecules. To date, the procedures employed for producing such substrates have involved either the floating off of carbon films from mica onto water and picking them up on EM grids or the deposition of carbon upon plastic covered grids, the plastic of which is subsequently dissolved away. We have now developed an efficient technique, unencumbered by the difficulties associated with the other procedures, for producing well delineated areas of thin carbon film of measurable thickness. In this procedure we utilize silk threads, about 15 microns in diameter, stretched across an adjustable frame having a 1” square opening (Fig. 1).
Effects of Ion Beam Milling on Surface Topography
Authors: Pawar P.G. , Duhamel P. , Monk G.W.
Published: June 2020

A beam of ions of mass greater than a few atomic mass units and with sufficient energy can remove atoms from the surface of a solid material at a useful rate. A system used to achieve this purpose under controlled atmospheres is called an ion miliing machine. An ion milling apparatus presently available as IMMI-III with a IMMIAC was used in this investigation. Unless otherwise stated, all the micro milling operations were done with Ar+ at 6kv using a beam current of 100 μA for each of the two guns, with a specimen tilt of 15° from the horizontal plane.

It is fairly well established that ion bombardment of the surface of homogeneous materials can produce surface topography which resembles geological erosional features.
Image Enhancement in the Emission Electron Microscope
Authors: McCune R. C.
Published: June 2020

A thermionic emission microscope designed by Eichen, and described in the literature, has been modified to allow the use of the Bendix Chevron type Channel Electron Multiplier Array (CEMA) for purposes of image enhancement. The CEMA provides a means of obtaining a spatial distribution of the electron emission occurring on the surface of the specimen, and as such provides a unique approach to problems of obtaining both thermionic emission images at relatively low temperatures and images produced by the phenomenon of exoelectron emission.

In order to observe single electron emissions on a phosphor screen, it is essential that an electron multiplier be operated at gains approaching 107.
Practical Aspects of High Resolution Transmission Electron Microscopy
Authors: de Harven Etienne , Sato Toru
Published: June 2020

Observations of biological ultrastructures bv electron microscopy are, in most cases, limited to a resolution of approximately 20 Å while, on the other hand, today's electron microscopes easily resolve 2 Å on non-biological objects. Thus, one order of magnitude seems generally unavailable for biological research. In order to take fuller advantage of the maximum resolving power of these microscopes, test specimens should first be studied to increase technical efficiency in high resdution imaging. For example, the graphite high resolution test, originally proposed by Heidenreich has proven of great value in this respect. However, the usefulness of this test re-1 mained limited as long as the direct magnification of the microscopes did not allow the visual recognition of the 3.4 Å periodic structure of graphite.
Morphological Features Associated with Polished Quartz Surfaces
Authors: Hart R. K. , Hicklin W. H.
Published: June 2020

The ability of quartz crystal units to perform as highly precise single sideband resonators for frequency control is marred by their long-term aging characteristics. After a stabilization period of four weeks, during which time crystals are maintained at their upper turning point temperature, a long-term aging rate of <±2xl0-10 /week frequency deviation is desired. Various explanations of this frequency drift greater than this value have been proposed (1,2). One of the most prevalent theories of quartz aging is that it results from ·minute changes that occur over a period of time in the chemical and physical nature of the resonator surface. In a carefully designed program to construct very low-aging quartz resonators, we included electron optical surface characterization techniques.
Direct Observations of the Epitaxial Growth of Sputtered Ag on Si
Authors: Maa J. S. , Hutchinson Thos. E.
Published: June 2020

The growth of Ag films deposited on various substrate materials such as MoS2, mica, graphite, and MgO has been investigated extensively using the in situ electron microscopy technique. The three stages of film growth, namely, the nucleation, growth of islands followed by liquid-like coalescence have been observed in both the vacuum vapor deposited and ion beam sputtered thin films. The mechanisms of nucleation and growth of silver films formed by ion beam sputtering on the (111) plane of silicon comprise the subject of this paper. A novel mode of epitaxial growth is observed to that seen previously.

The experimental arrangement for the present study is the same as previous experiments, and the preparation procedure for obtaining thin silicon substrate is presented in a separate paper.
Reinforcement of Polyester Castings by Silane Treatment of Inorganic Fillers
Authors: Freeman H. A. , Plueddemann E. P.
Published: June 2020

Mechanical properties and chemical resistance of mineral-filled organic composites are often improved markedly by modifying the interface with a trace of silane coupling agent. Replication and scanning electron microscopy provide insight into the structural behavior of these materials. The present study was made to determine microscopically the effect of one silane treatment on several filler types incorporated in polyester resin coatings.

Ground crystalline silica, precipitated calcium carbonate, and kaolin clay were compared, with and without silane pretreatment, as fillers in the polyester. Castings with 50% filler loading-were used. As shown in the accompanying table (Table I), silane pretreatment of the silica filler appreciably increased the flexural strength of the resulting polyester casting.
The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface
Authors: Herfert R. E.
Published: June 2020

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.
Dependence of Intergranular Fracture on Boundary Topography and Cohesion
Authors: Doherty J. E. , Giamei A. F. , Kear B. H. , Steinke C. W.
Published: June 2020

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.

For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.
Deformation Structure of Beta Titanium Alloys
Authors: Fujishiro S. , Roberson J. A.
Published: June 2020

Prototype commercial beta titanium alloys (Ti-11.5w/oMo-6w/oZr-4.5w/oSn, so called beta-III) single crystals have been deformed by compression, and the deformation structures were investigated by optical metallography, transmission electron microscopy and X-ray technique. Macro grain crystals have been grown by a conventional strain anneal technique, and single crystals were prepared by cutting large grains. One large grain, whose surface is nearly a (001) plane, was cut into three parallelopiped crystals, approxi- mately 1/4 × 1/4 × 3/8”. After 2% of compression strain was introduced to these crystals at room temperature, TEM was performed on thin films which were prepared from the slices cut,near parallel to (001) planes.
In Situ Observations of Precipitation
Authors: Butler E.P. , Swann P.R.
Published: June 2020

This paper reports preliminary observations of precipitation in several alloy systems obtained with an accurately calibrated hot stage in the AEI EM7 1MeV microscope at Imperial College. These observations, in >1μ thick specimens where precipitation is generally more characteristic of bulk, provide experimental evidence which allows existing theories of precipitation reactions to be examined and critically evaluated.

Cellular decomposition in Al-Zn and Mg-Al The cellular reaction in Al-48wt%Zn has been studied in the temperature range 75-250°C. Nucleation occurs rapidly on grain boundaries by the formation of individually nucleated ‘nodules’ which quickly impinge to form an approximately planar cell interface.
The Alteration of the Pore Spaces in Sandstones
Authors: Ferrell R. E. , Paulson G. G.
Published: June 2020

The pore spaces in sandstones are the result of the original depositional fabric and the degree of post-depositional alteration that the rock has experienced. The largest pore volumes are present in coarse-grained, well-sorted materials with high sphericity. The chief mechanisms which alter the shape and size of the pores are precipitation of cementing agents and the dissolution of soluble components. Each process may operate alone or in combination with the other, or there may be several generations of cementation and solution.

The scanning electron microscope has ‘been used in this study to reveal the morphology of the pore spaces in a variety of moderate porosity, orthoquartzites.
A Scanning Electron Microscope Study of the Frustule Structure of the Freshwater Diatom Melosira Granulata (Ehr.) Ralfs
Authors: Abbott W. H. , Pollard C. O.
Published: June 2020

Frustules of the freshwater diatom Melosira granulata (Ehr.) Ralfs from a freshwater diatomite of Miocene age and recent frustules of this species from Reelfoot Lake, Tennessee were examined under a scanning electron microscope to determine fine structure generally not seen or poorly seen with the conventional light microscope.

The terminology used to describe frustule structure in this study was originated by Hendy.

Melosira granulata generally grows in chains of two connected frustules with each frustule containing two valves or halves. The connection between frustules is accomplished by the encasing of the adjacent valves of two frustules by a structure called the girdle (Fig. 1a).
The Resolution and Contrast in Biological Sections Determined by Inelastic and Elastic Scattering
Authors: Misell D. L.
Published: June 2020

In the electron microscopy of biological sections the adverse effect of chromatic aberration on image resolution is well known. In this paper calculations are presented for the inelastic and elastic image intensities using a wave-optical formulation. Quantitative estimates of the deterioration in image resolution as a result of chromatic aberration are presented as an alternative to geometric calculations. The predominance of inelastic scattering in the unstained biological and polymeric materials is shown by the inelastic to elastic ratio, I/E, within an objective aperture of 0.005 rad for amorphous carbon of a thickness, t=50nm, typical of biological sections; E=200keV, I/E=16.
Resolution, Contrast and Interpretation of HVEM Images of Crystals
Authors: Thomas L. E. , Lally J. S. , Fisher R. M.
Published: June 2020

In addition to improved penetration at high voltage, the characteristics of HVEM images of crystalline materials are changed markedly as a result of many-beam excitation effects. This leads to changes in optimum imaging conditions for dislocations, planar faults, precipitates and other features.

Resolution - Because of longer focal lengths and correspondingly larger aberrations, the usual instrument resolution parameter, CS174 λ 374 changes by only a factor of 2 from 100 kV to 1 MV. Since 90% of this change occurs below 500 kV any improvement in “classical” resolution in the MVEM is insignificant. However, as is widely recognized, an improvement in resolution for “thick” specimens (i.e. more than 1000 Å) due to reduced chromatic aberration is very large.
SEM Resolution and Test Specimen
Authors: Black J. Temple
Published: June 2020

Criteria for a resolution and test specimen for the SEM have been presented by Ballard. A resolution standard should have known simple geometric form and well defined structure with excellent unaided contrast at high magnifications. Black regions should in fact be space and resolution measurements should be made from edge-to-edge or point-to-point across material, not space. A standard should also be well defined in terms of materials or atomic number in that SEM resolution is strongly dependent upon beam penetration (and therefore Z numbers) as well as electron optical performance. This eliminates alloys where microcomposition cannot be varified up resolution levels that a standard needs. While coating is not recommended, if the standard specimen were the coating and vice versa, then vacuum evaporation would serve as the means to produce specimens of like geometry and variable Z number.
Metal Cutting in the Scanning Electron Microscope
Authors: Black J. Temple , Ramalingam S.
Published: June 2020

One of neglected features of a SEM is its applicability to mechanical testing and deformation processes. Metal cutting plastic deformations can be viewed at high magnification with slow deformation rates in the TV mode (rapid scan) in standard SEM-TV setups. Two force or orthogonal cutting as shown in Figure 1 can be performed in situ in a specially designed deformation stage which can be substituted for the normal specimen holder (in the JEOL JSM U3) and inserted in the goniometer stage. The deformation stage is driven externally by a motor connected to a rod which passes through the specimen air lock door and feeds the workpiece. Figures 2 and 3 show stop action micrographs of a metal cutting process as performed in the SEM under normal vacuum conditions. Thus, this large strain, high strain process could be dynamically studied and recorded at magnifications up to 5000X.
An Efficient Reduced Raster and Manual Line Set Control System For Jeol JSM-U2 and JSM-U3 Scanning Electron Microscopes
Authors: Estry H. W. , Allard L. , Bigelow W. C.
Published: June 2020

A reduced area visual raster with a rapid frame scan greatly facilitates focussing and correction of astigmatism in scanning electron microscopes. In cases where it is desired to set image brightness and contrast at the best levels for photographing a small image feature, it is also useful to be able to manually adjust the vertical position of the horizontal scan line so that it remains stationary over the feature of interest. The optimum contrast for this image feature can then be easily set using a wave form monitor. These operations should be performed as rapidly and efficiently as possible, particularly when high magnification micrographs are taken, in order to minimize the effects of the electron beam on the sample, and to reduce operator fatigue.
Pitfalls in Optical Filtering Techniques
Authors: Haydon Glen B. , Scales Donald J.
Published: June 2020

It is now a popular procedure to apply optical filtering techniques to noisy electron micrographs of a variety of biological structures in order to improve image quality. However, a point overlooked by many investigators is that in using a spatial filter to enhance a micrograph, we are imposing an assumed model of the structure upon the image.

According to Abbe's theory of image formation, an image in an optical system is the result of a double diffraction process. The image can be altered by inserting a filter in the back focal plane of the imaging lens.
100kV Boride-Emitter Electron Gun System for Conventional and Scanning Transmission Microscopy
Authors: Ahmed H. , Nixon W. C.
Published: June 2020

Under certain conditions the greater brightness available from a boride emitter electron gun could be of advantage in both conventional and scanning transmission electron microscopy. For example, in conventional transmission microscopy it should be possible to obtain more coherence in the illuminating system, leading to improved contrast and shorter recording timeswhen weak beam techniques or lattice fringe imaging is required. Selected area diffraction from smaller regions and improved x-ray counting statistics are other potential benefits. In scanning transmission microscopy the greater brightness gives a substantial advantage, in probe current for the same probe diameter, over the tungsten hairpin filament.
Characterization of Particulates From Engine Exhaust
Authors: Paulson G. G. , Ferrell R. E.
Published: June 2020

The subject of vehicle emissions has received much attention during the past several years. The particle size as well as the chemistry of the exhaust particles, particularly the ones containing lead, has been a controversial subject because of environmental implications and the effects of lead compounds on the effectiveness of catalytic converters. Although it has been fairly well established by X-ray diffraction studies that the solids consist of a complex mixture of carbonaceous matter and inorganic salts, there has been disagreement as to the particle sizes and ultimate chemistry of the lead compounds in the exhaust which result from the addition of tetraethyllead (TEL). In general, the TEL is volatilized in the combustion chamber and is “scavenged” by halides, typically Br and Cl which are added as ethyl dibromide and chloride.
Three Methods For the Preparation of High-Resolution Freeze-Dried Specimens in a Freeze-Etch Module
Authors: Steere Russell L.
Published: June 2020

The first satisfactory freeze-dry procedure for electron microscopy was described by Williams. An improvement permitted the shadowing of specimens in the same system where freeze-drying was accomplished. Our freeze- etch module is ideal also for the preparation of freeze-dry specimens and high-resolution specimens have been prepared by the 3 different procedures.

Procedure #1: A particulate suspension in distilled water or a volatile buffer is sprayed onto a thin mica sheet held down with high vacuum grease to a flat-topped specimen cap clamped onto the specimen stage (all pre-cooled to −150°C). Freeze-drying is accomplished with a vacuum of 2 × 10−6 Torr and specimen temperature of −98 to −75° (approximately 15 min).
A Temperature-Controllable Hydration Stage for the Siemens Elmiskop 1A
Authors: Hui S. W. , Parsons D. F.
Published: June 2020

Hydration stages for electron microscopes have been extensively developed by this laboratory in the last few years. we report here an improved version of the hydration stage for the Siemens Ia Elmiskop. The special features of this stage are that: 1) it involves a minimal amount of deviation from the existing optics of the microscope, 2) the water reservoir is a part of the metallic stage therefore the temperatures of the specimen and of the liquid-vapor system are the same always, 3) the entire stage is thermally insolated from the microscope, its temperature being controlable, 4) the alteration of the microscope in order to accomodate the stage is kept to a minimum. The simplicity in the construction and operation of this stage makes it attractive as a general accessory.
The Hardness of Epoxy Embedding Compounds For Ultrathin Sectioning
Authors: Poolsawat Samuel S.
Published: June 2020

Although there have been numerous studies concerning a variety of procedures for epoxy compounding, no report on optimal hardness for ultrathin sectioning has been defined. The most widely used compounding media (Epon, Araldite-Epon, and others) do not always obtain optimal hardness and may, infact, vary considerably. For example, Epon and Araldite-Epon blocks do not section well, especially with glass knives (Figs. 1,2,3, and 4).

Physical properties of a series of cured epoxy resins were measured according to ASTM test proceduresor according to methods designed for block testing (Fig. 6). Cured epoxy resin hardness can be precisely controlled systematically and can be measured by using Shore D Hardness Test Instrument.
Wide Field Electron Microscopy: The Sublimation of Epon-Araldite
Authors: Yang Grace C. H. , Morrison A. B.
Published: June 2020

To emphasize the best feature of this technique, the term “wide field” is used throughout the text instead of the usual “scanning range magnification” or “low magnification”. Wide field electron microscopy presently is not being fully utilized in many laboratories, perhaps because the quality of the electron micrograph obtained is not worthy of the supposedly long and tedious specimen preparation. We report here that the quality of the wide field electron micrograph can be greatly enhanced by using the old “sublimation trick” for the methacrylate section.

Two kinds of embedment formula were tested: Luft's Epon (mixture A:B= 6;4), and Mollenhauer's Epon-Araldite mixture 1. Only the Epon-Araldite showed the “foot print” of the electron beam (fig. 1).
Localization of Cadmium in the Mouse Liver Cells Induced by Acute Cadmium Poisoning
Authors: Mizuhira V. , Kimura M.
Published: June 2020

Acute Cadmium-poisoning of a mouse was induced by two intraperitoneal injections of U00 ppm Cadmium chloride solution. 2 hrs after the second injection, the mouse liver was cut into small blocks in the following chilled prefixative. The same volume of 8 % paraformaldehyde and 1/7M veronal acetate buffer solution was mixed and adjusted to pH 7-0, then Oxine was saturated in this fixative. Oxine makes insoluble precipitate with Cadmium(Cd) sensitively(0.1𝛄) Prefixation was proceeded by 2 hrs in ice. The blocks were postfixed with 1 % OsO4, followed by dehydration and embedded in Epon. G-6-Pase(Gomori) and acid phosphatase(Karnovsky) were also examined. Hitachi HU-11E was used for ordinary observations and selected area electron diffraction, and JEOL-IOO-B fitted with nuclear diode Silicon-detector for energy dispersive analysis of X-rays from an Epon embedded section(EDAX), and transmission type scanning electron image system(TSEl).
Localization of Gallium-67 in Peritoneal Cells by Electron Microscopic Autoradiography
Authors: Swartzendruber D. C. , Idoyaga-Vargas Norma L.
Published: June 2020

The radionuclide gallium-67 (67Ga) localizes preferentially but not specifically in many human and experimental soft-tissue tumors. Because of this localization, 67Ga is used in clinical trials to detect humar. cancers by external scintiscanning methods. However, the fact that 67Ga does not localize specifically in tumors requires for its eventual clinical usefulness a fuller understanding of the mechanisms that control its deposition in both malignant and normal cells. We have previously reported that 67Ga localizes in lysosomal-like bodies, notably, although not exclusively, in macrophages of the spocytaneous AKR thymoma. Further studies on the uptake of 67Ga by macrophages are needed to determine whether there are factors related to malignancy that might alter the localization of 67Ga in these cells and thus provide clues to discovering the mechanism of 67Ga localization in tumor tissue.
Effect of ADH on Rat Renal Papilla, an Ultrastructural and Cytochemical Study
Authors: Sun C. N. , White H. J. , Towbin E. J.
Published: June 2020

Diabetes insipidus and compulsive water drinking are representative of two categories of antidiuretic hormone (ADH) lack. We studied a strain of rats with congenital diabetes insipidus homozygote (DI) and normal rats on an isocaloric fortified dilute milk diet. In both cases, the collecting tubules could not concentrate urine. Special staining techniques, Alcian Blue-PAS for light microscopy and lanthanum nitrate for electron microscopy were used to demonstrate the changes in interstitial mucopolysaccharides (MPS). The lanthanum staining was done according to the method of Khan and Overton.

Electron microscopy shows cytoplasmic lesions, vacules, swelling and degenerating mitochondria and intercellular spaces (IS) in the collecting tubule cells in DI and rats on milk diet.
Intranuclear Crystals in Regenerating Canine Kidneys
Authors: Osborne D.G. , McCormack L.J. , Magnusson M.O. , Kiser W.S.
Published: June 2020

During a project in which regenerative changes were studied in autotransplanted canine kidneys, intranuclear crystals were seen in a small number of tubular epithelial cells. These crystalline structures were seen in the control specimens and also in regenerating specimens; the main differences being in size and number of them. The control specimens showed a few tubular epithelial cell nuclei almost completely occupied by large crystals that were not membrane bound. Subsequent follow-up biopsies of the same kidneys contained similar intranuclear crystals but of a much smaller size. Some of these nuclei contained several small crystals. The small crystals occurred at one week following transplantation and were seen even four weeks following transplantation. As time passed, the small crystals appeared to fuse to form larger crystals.
The Application of Scanning Electron Microscopy in the Investigation of Human Gastrointestinal Pathology
Authors: Siew S.
Published: June 2020

A significant advance in our knowledge of gastrointestinal pathology has been achieved through endoscopy of the accessible portions of the alimentary tract. This procedure has allowed the evaluation of morphological characteristics of the mucosa by means of direct viewing in situ and through microscopy (light and transmission electron) of biopsies taken from selected areas. The importance of examination of the three dimensional configuration of the mucosal surface has been recognized, particularly in the assessment of the intestinal villi in cases of malabsorption, where it is recommended that the biopsies should be examined first by means of the dissecting microscope. Therefore, there is an obvious indication here for scanning electron microscopy, with its far greater potential.
The Challenge of Soft Tissue Preparation For the S.E.M.
Authors: Tyler W. S. , Nowell J. A.
Published: June 2020

Until recently it was commonly thought that the best way to study morphology with the SEM was to get the sample into the microscope with a minimum of preparation and start taking pictures. The rapidly increasing numbers of studies on soft tissue morphology have indicated that some investigators are still satisfied with this approach, and are content to compare artifacts. But the majority of investigators have found it necessary to take extreme care in handling soft tissue from the time of its removal from the organ, host, or growth medium to the final micrograph, in order to prevent or inhibit deformation.
A Scanning Electron Microscope Study of Isolated Guard Cells
Authors: Dayanandan P. , Kaufman P. B.
Published: June 2020

A three dimensional appreciation of the guard cell morphology coupled with ultrastjuctural studies should lead to a better understanding of their still obscure dynamics of movement. We have found the SEM of great value not only in studies of the surface details of stomata but also in resolving the structures and relationships that exist between the guard and subsidiary cells. We now report the isolation and SEM studies of guard cells from nine genera of plants.

Guard cells were isolated from the following plants: Psilotum nudum, four species of Equisetum, Cycas revoluta, Ceratozamia sp., Pinus sylvestris, Ephedra cochuma, Welwitschia mirabilis, Euphorbia tirucalli and Allium cepa.
Ultrastructural Localization of Phycocyanin in the Acidophilic, Thermophilic Alga, Cyanidium Caldarium
Authors: Edwards M. R. , Mainwaring J. D.
Published: June 2020

Although the general ultrastructure of Cyanidium caldarium, an acidophilic, thermophilic alga of questionable taxonomic rank, has been extensively studied (see review of literature in reference 1), some peculiar ultrastructural features of the chloroplast of this alga have not been noted by other investigators.

Cells were collected and prepared for thin sections at the Yellowstone National Park and were also grown in laboratory cultures (45-52°C; pH 2-5). Fixation (glutaraldehyde-osmium), dehydration (ethanol), and embedding (Epon 812) were accomplished by standard methods. Replicas of frozenfracture d- etched cells were obtained in a Balzers apparatus. In addition, cells were examined after disruption in a French Press.
Preliminary Observations on Lignification in Tracheids of Balsam Fir
Authors: Schwarzmann Joseph M. , Kutscha Norman P.
Published: June 2020

Lignin, which ranks second only to cellulose as the most abundant natural product on earth, is a complex three-dimensional aromatic polymer formed in plant cell walls. Lignin is deposited (lignification) as an encrusting matrix within the cellulosic framework of cell walls, stabilizing the fully enlarged cell, and acts as an adhesive between adjacent cells. Lignification has been studied in very few tree species. The purpose of this study was to determine the lignification sequence in balsam fir tracheids, using transmission electron microscopy and to compare it with the known sequence in Pinus radiata. Bark-cambium-wood'specimens of balsam fir were removed from growing trees and fixed in unbuffered 2% potassium permanganate which acted as a combination fixative and electron-dense lignin stain. Specimens were embedded, sectioned and stained with Reynolds’ lead citrate stain.
Ectodesmata as Revealed By Freeze-Etch Preparations of Plant Epidermal Cell Walls
Authors: Lyon N.C. , Mueller W. C.
Published: June 2020

Schumacher and Halbsguth first demonstrated ectodesmata as pores or channels in the epidermal cell walls in haustoria of Cuscuta odorata L. by light microscopy in tissues fixed in a sublimate fixative (30% ethyl alcohol, 30 ml:glacial acetic acid, 10 ml: 65% nitric acid, 1 ml: 40% formaldehyde, 5 ml: oxalic acid, 2 g: mecuric chloride to saturation 2-3 g). Other workers have published electron micrographs of structures transversing the outer epidermal cell in thin sections of plant leaves that have been interpreted as ectodesmata. Such structures are evident following treatment with Hg++ or Ag+ salts and are only rarely observed by electron microscopy. If ectodesmata exist without such treatment, and are not artefacts, they would afford natural pathways of entry for applied foliar solutions and plant viruses.
Review of the Radiation Damage Problem of Organic Specimens in Electron Microscopy
Authors: Reimer L.
Published: June 2020

Most information about a specimen is obtained by elastic scattering of electrons, but one cannot avoid inelastic scattering and therefore radiation damage by ionisation as a primary process of damage. This damage is a dose effect, being proportional to the product of lectron current density j and the irradiation time t in Coul.cm−2as long as there is a negligible heating of the specimen.

Therefore one has to determine the dose needed to produce secondary damage processes, which can be measured quantitatively by a chemical or physical effect in the thin specimen. The survival of micro-organisms or the decrease of photoconductivity and cathodoluminescence are such effects needing very small doses (see table).
Electron Radiation Damage on thin Films of Phenylalanine
Authors: Lin P. S. D.
Published: June 2020

Consecutive observation of the mass loss and change in electron energy loss spectra are being carried on In a simple field emission scanning mlcroscope. The specimens are prepared by slow sublimation onto thin carbon films on a copper grid.

For mass loss measurement, unscattered electrons Nun are counted, W'lich Is related to Incident beam Intensity N0 by Nun = N0 exp(-(ai+ae)t), where tIs a specimen thickness, ae, ai the Inverse of the mean free path for elastic and Inelastic scattering, respectively. With 20 KeV and 12 mrad aperture angle, most of the elastically scattered electrons are stopped by the aperture. The Inelastically scattered electrons arefll tered by the spectrometer.
The Ultrastructure of the Giant Pharyngeal Gland Nuclei of Ascaris Lumbricoides
Authors: Kleinhenz Margie J. , Swartz Frank J.
Published: June 2020

This report on the ultrastructure of Ascaris lumbricoides pharyngeal gland nuclei is concerned with nuclear differentiation in exceptionally large, highly polyploid nuclei. All somatic cells of Ascaris undergo chromatin diminution but the pharyngeal gland nuclei subsequently accumulate extremely large amounts of DNA. These complex nuclei, two subventral and one dorsal (Insert), may attain volumes in the adult of 900,000 μ3 and 7,000,000 μ3 respectively. Their extrapolated polyploid equivalents, measured by Feulgen microdensitometry and compared to sperm and egg values, are as high as 12,000 and 100,000. At the light microscopic level these nuclei exhibit multiple nucleol, membrane bound proteinaceous bodies, cyto-plasmic invaginations, and unusual basophilic clumps having DNA cores surrounded by RNA-containing structures.
Compound Symbiosis in Peridinium Balticum
Authors: Tomas R. N.
Published: June 2020

Peridinium balticum appears to be unusual among the dinoflagellates in that it possesses two DNA-containing structures as determined by histochemical techniques. Ultrastructurally, the two dissimilar nuclei are contained within different protoplasts; one of the nuclei is characteristically dinophycean in nature, while the other is characteristically eucaryotic. The chloroplasts observed within P. balticum are intrinsic to an eucaryotic photosynthetic endosymbiont and not to the dinoflagellate. These organelles are surrounded by outpocketings of endoplasmic reticulum which are continuous with the eucaryotic nuclear envelope and are characterized by thylakoids composed of three apposed lamellae. Girdle lamellae and membranebounded interlamellar pyrenoids are also present. Only the plasmalemma of the endosymbiont segregates its protoplast from that of the dinophycean cytoplasm. The exact nature of this symbiotic relationship is at present not known.
Ultrastructure of Pentastome Nymph Integument
Authors: Demaree Richard S.
Published: June 2020

Pentastomes are endoparasites which share both arthropod and annelid characteristics, but apparently cannot be placed in either phylum. The phylum Pentastomida is often placed with the phyla Onycophora and Tardigrada as a group called Pararthropoda or Oncopoda because they all have unjointed limbs with claws and a cuticle that undergoes molting. A study of onycophoran cuticle revealed that the enigmatic organisms, which also have arthropod and annelid affinities, possess an integument remarkably similar to arthropod and quite unlike annelid cuticle. In another study, tardigrade cuticle resembled nematode cuticle more closely than that of any other phylum. Pentastome integument (cuticle, epidermis and associated structures) was examined in this study to determine the morphology of nymph cuticle and to compare it with that of other animals.
6-Hydroxydopamihe, Norepinephrine Depletion, and the Ultrastructure of Cardiac Muscle
Authors: Hagopian Martin , Gershon Michael D. , Nunez Eladio A.
Published: June 2020

We have previously found that two drugs which alter tissue concentrations of biogenic amines also induce changes in the ultrastructure of cardiac tissue in active bats. Reserpine, which depletes stores of norepinephrine (NE) and 5-hydroxytryptamine (5-HT), leads to an increase in size and number of lipid droplets and glycogen granules, major structural changes in mitochondria and dilatation of the T-system. Parachlorophenyl-alanine which did not deplete NE but did deplete 5-HT by interfering with its biosynthesis, mimicked the action of reserpine on the lipid droplets of cardiac muscle but did not produce mitochondrial changes. This suggested that the changes in lipid droplets could not be related to cardiac NE. However, the other changes in cardiac ultrastructure that followed administration of reserpine could have been so related.
Mechanism of Tyramine Effects On Norepinephrine Pools in Purified Adrenergic Vesicles: Biochemical and Ultrastructural Correlates
Authors: Klein R. L. , Yen S. S. , Chen-Yen S. H. , Thureson-Klein Å.
Published: June 2020

Improved methods and the ability to obtain bovine splenic nerves with a minimal post-mortem delay permit the routine preparation of highly pure, 750Å, dense-core vesicles. In addition to yielding a much greater vesicle norepinephrine(NE):protein ratio, two NE pools were revealed for the first timel. At 30°C the vesicles lost 20% of their NE from a fast pool, T 1/2 = 4-5 min, apparently insensitive to ATP. The remaining NE was lost with T 1/2 = 35 min in the presence of ATP and 3 times faster without ATP.

Vesicles were incubated with 1μg 3H-1-NE/ml or together with equimolar 14C-tyramine(TA). With TA added, the half-lives for net NE loss from both pools are decreased ∼ 30%(Fig. 1). The initial peak for 14C-TA is reached and reversed within the first 15 min(Fig. 2).
Ultrastructure and Drug Metabolism in the Developing Guinea Pig
Authors: Kuenzig W. , Boublik M. , Kamm J.J. , Burns J.J.
Published: June 2020

Unlike a variety of other animal species, such as the rabbit, mouse or rat, the guinea pig has a relatively long gestation period and is a more fully developed animal at birth. Kuenzig et al. reported that drug metabolic activity which increases very slowly during fetal life, increases rapidly after birth. Hepatocytes of a 3-day old neonate metabolize drugs and reduce cytochrome P-450 at a rate comparable to that observed in the adult animal. Moreover the administration of drugs like phenobarbital to pregnant guinea pigs increases the microsomal mixed function oxidase activity already in the fetus.

Drug metabolic activity is, generally, localized within the smooth endoplasmic reticulum (SER) of the hepatocyte.
Cytopathologic Effects of Adriamycin on Murine Cardiac Tissue
Authors: Liss Robert H. , Ifrim Ina
Published: June 2020

Adriamycin and daunomycin are structurally related antibiotics used in the clinical management of neoplastic diseases. However, adriamycin has exhibited a higher therapeutic index against a wide variety of tumors and thus is currently of greater clinical interest. Like daunomycin, adriamycin produces a delayed, irreversible, lethal cardiac toxicity. The present study was initiated to compare the cytopathology of cardiac tissue from adriamycin-treated mice with previous ultrastructural observations of myocardium from daunomycin-treated rodents.

Four to eight days after drug administration, myocardium from the ventricles of 8 moribund BDF1 male mice which received a single intraperitoneal dose of adriamycin (20 mg/kg), and from controls dosed with physiologic saline, was fixed in glutaraldehyde or Karnovsky's glutaraldehyde-paraformaldehyde and prepared for electron microscopy.
Topographic Features of Neisseria Catarrhalis Strains
Authors: Wistreich G. A. , Baker R. F. , Hammond W. B. , Ivler D.
Published: June 2020

The surface features of several bacterial species belonging to the Neisseriaceae including Neisseria gonorrhoeae, N. meningitidis and Veillonella parvula have been reported. During fimbriation studies with N. catarrhalis negative staining revealed a surface pattern differing from those found with other species of this genus. This report presents a comparative study with three N. catarrhalis strains. Consideration is given only to the physical aspects of intact cell wall structures.

Of the three Neisseria catarrhalis strains used, one came from the stock culture collection of the Bacteriology Section, Division of Biological Sciences, University of Southern California, Los Angeles, while the remaining strains (ATCC 8176, ATCC 8193), were from the American Type Culture Collection, Rockville, Maryland.
Electron Microscopy of an Intracellular Response of Tetrahymena Pyriformis to Fluids From Normal Animals
Authors: Brenner L. J. , Osborne D. G. , Schumaker B. L.
Published: June 2020

It was previously reported that log phase Tetrahymena pyriformis (strain WHg), washed free of growth medium, after mixing with normal human or rabbit serum or mouse ascites fluid, gave rise after several hours to numerous large and small bodies in the cytoplasm, as visualized by the light microscope. Generally, the large bodies remained in the posterior portion of the animal, while the small ones were localized near the anterior end. Stained preparations showed small Sudan IV positive bodies and large PAS positive bodies. Electron micrographs also identified the small bodies as lipid and showed the large ones to be enclosed within a membrane (Fig. 1) and unlike anything yet described for this organism. Whether all these large bodies correspond to the PAS positive bodies on the slide preparations is uncertain.