bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Extemporaneous Lead Citrate Stain for Electron Microscopy
Authors: Fahmy Aly 
Published: June 2020

The use of lead stains for thin sections in electron microscopy is widespread. Of the various compounds, lead citrate is commonly employed. However, Reynolds' technique for its preparation from lead nitrate and sodium citrate is time-consuming. With the availability of lead citrate commercially, from at least two suppliers (K & K Laboratories, Inc., Plainview, N. Y. and Polyscience, Inc., Rydal, Pennsylvania, 19046) we have investigated the suitability of this commercial form for the staining of thin sections.We attempted to develop a technique for the simple and instantaneous preparation of a staining solution to be used fresh each time and then discarded. Following multiple trials at various concentrations, we formulated its preparation in a “cookbook” fashion involving a minimum of weighing and measuring. Previously boiled, cooled, double-distilled, millipore-filtered water, which can be stored in the refrigerator, is used. To 50 ml. of water add one pellet of sodium hydroxide (Merck) and stir until dissolved.
Modification of Pineal Ultrastructure by Exogenous Hormones
Authors: Turner R. A. , Rodin A. E. , Roberts D. K. 
Published: June 2020

There have been many reports which establish a relationship between the pineal and sexual structures, including gonadal hypertrophy after pinealectomy, and gonadal atrophy after injection of pineal homogenates or of melatonin. In order to further delineate this relationship the pineals from 5 groups of female rats were studied by electron microscopy:ControlsPregnant ratsAfter 4 weekly injections of 0.1 mg. estradiol benzoate.After 8 daily injections of 150 mcgm. melatonin (pineal hormone).After 8 daily injections of 3 mg. serotonin (melatonin precursor).No ultrastructural differences were evident between the control, and the pregnancy and melatonin groups. However, the estradiol injected animals exhibited a marked increase in the amount and size of rough endoplasmic reticulum within the pineal cells.
Pores in the Plasma Membranes of Myocardial Cells
Authors: Epling Glenwood P. 
Published: June 2020

Heart muscle samples were collected from the right ventricles of twelve mature cattle and twelve pigs at slaughter and immediately prepared for electron microscopy by immersion in three different fixatives: 40% OsO4 dissolved in CCl4, 1.5% OsO4 in S collidine buffer, and in 2.5%. glutaraldehyde followed by 1.5%, OsO4. Some tissue from each animal was processed in each fixative and was embedded in either an epoxy resin or in a polyester resin. Sections were cut at 300 to 600 Å in thickness on a thermally advancing microtome, using glass and diamond knives, and were mounted on copper mesh grids. Uranyl acetate and lead citrate stains were used. Tissues were examined in an RCA, EMU-3F electron microscope.In both the cattle and pigs, some heart samples contained myocardial cells with plasma membranes which invaginated into the cells to form tubular appearing channels. These channels occurred in addition to the transverse sarcotubular system, and in addition to the pinocytotic vesicles. The basement membrane which surrounds myocardial cells did not extend into the invaginations, but bridged over their external apertures.
Macromolecular Pattern in the Cell Envelope of a Bacillus Species
Authors: Carnahan J. , Brinton C. C. , McNary J. E. 
Published: June 2020

The presence of a structured external surface layer of the cell envelope from Spirillum serpens was first described by Houwink. This “macromolecular monolayer” consists of a hexagonal array of particles. A few examples of tetragonal patterns in bacterial cell envelopes have been reported but the structural elements have not been chemically characterized. The present study is directed towards the analysis of a tetragonal pattern of a Bacillus species isolated from sewage.The pattern could be observed on cells from young cultures negatively stained with potassium phosphotungstate (PTA). Cultures stored in the cold for several days or weeks undergo autolysis yielding large sheets of intact pattern. Electron micrographs of overlapping macromolecular monolayers show characteristic Moiré patterns (Fig. l).
The Presence of Packets of Bio-Adhesives in Sea Cucumbers
Authors: Harrison G. A. 
Published: June 2020

Secretory packets have been seen and described in several species of starfish (Class Asteroidea). Since many species of sea cucumbers also possess tube feet with suckers and also adhere to surfaces in the same manner as starfish, it was decided to examine their tube feet for secretory packets. Material for these studies was fixed in 3.5 to 5 % glutaraldehyde in phosphate buffer, post-fixed in osmium tetroxide also in phosphate buffer and embedded in Araldite 502 or Epon 8l2. Material for colloidal thorium studies was dehydrated and embedded in GMA.Thin sectioning revealed a secretory packet which, although similar in size and shape to that found in starfish, differed radically from it in internal structure. All sea cucumbers investigated have shown these three components, 1) a fibrous area, 2) a light granular area, and 3) a dark granular area. The species differ somewhat in their arrangement of these components. Three of the species resemble “toadstools” and a fourth has an “onyx ring” configuration.
Application of the Short Focal Length Objective to Biological Substances
Authors: Harri W. W 
Published: June 2020

Possible improvement in resolving power by use of objective focal lengths of 2 mm in the conventional transmission electron microscope has been described by Heidenreich and Armbruster and by H. Fernandez-Moran. A modified Siemens Elmiskop IA has been used to examine a plasma protein, some polyamino acids, sRNA, 50s ribosome preparations, serum albumin, and myoglobin in unsupported specimens.Characteristics of the images obtained in defocussed images will be discussed in relation to the molecular structure of these compounds.
External Photography of the Microscope Image
Authors: Anderson K. , Kenway P. B. 
Published: June 2020

It has been shown that the direct exposure of the electron image of the microscope to a photographic emulsion is an almost perfect recording system (Valentine and Wrigley 1964). This method of recording, however, has the disadvantage that it is necessary to introduce the photographic emulsions into the vacuum of the microscope. In order to overcome this difficulty the possibilities of photographing a phosphor screen on which the electron image is displayed have been investigated.The apparatus used consisted of a transmission phosphor screen located below the normal plate camera of an EM6G electron microscope. The image produced was then photographed using an 35mm camera fitted with an F/I lens. The density - exposure curve for a number of photographic emulsions was obtained. Some of the results obtained are shown in Fig. 1. It can be seen from these results that exposures comparible with the direct exposure of the electrons to a photographic plate can be obtained.
On the Formation of Shock-Twins in Prestrained Armco Iron
Authors: Mahajan S. 
Published: June 2020

The formation of a deformation twin can he divided into two stages: nucleation of a twin lamella, and growth of this lamella into an observable twin. However, the second stage can be further subdivided into three sub-headings: (i) propagation of the lamella parallel to its long dimension, i.e., the longitudinal direction, (ii) thickening parallel to its short dimension, and (iii) growth of this nucleus in a direction perpendicular to the plane containing the long and the short dimensions.The purpose of the present investigation was to study the effect of existing substructure on the formation of mechanical twins in Armco iron. These twins were produced by shock-loading the annealed and prestrained samples to 50 and 100 Kbars, using a plane-wave generator. It should be emphasized that the desired objective can be achieved without resorting to shockloading, but thin foils from an impulsively loaded sample possess the advantage of containing many more twins and twin nuclei than foils from more conventionally stressed material, thus facilitating the analysis of results.
Thermal Treatment of Non-Crystalline Calcium Phosphate
Authors: Gerdes R. J. , Weber J. C. 
Published: June 2020

The first solid phase of calcium phosphate salts which are prepared "by rapid precipitation from alkaline solutions gives an x-ray diffraction pattern characteristic of amorphous materials. Investigations by methods of electron microscopy show that the aperiodic nature of the atomic structure is reflected in the external morphology of these precipitates; the particles are spheroids with electron.translucent cores. The present study was undertaken to ascertain the influence of heat treatment in the electron microscope on these amorphous calcium phosphates.The calcium phosphate salt was prepared at 25°C by rapid mixing of alkaline calcium and phosphate solutions of sufficient concentrations to produce instantaneous precipitation. A Ca/P molar ratio of 1.5 indicates that the product obtained is a neutral tricalcium phosphate. The amorphous material was prepared for examination in the electron microscope by suspending the dry solid in distilled water or in benzene or trichlorethylene. A drop of one of these suspensions was evaporated on a carbon film which covered an electron microscope grid.
Epitaxial Growth of Sodium Chloride Films Evaporated Upon Mica
Authors: Shimaoka G. , Herold J. F. 
Published: June 2020

It has been reported by Schulz using an electron diffraction technique that evaporated sodium chloride crystals grow epitaxially upon heated mica. However, several important points, for instance, the temperature at which epitaxial growth is completed and how the deposits nucleate upon the substrate, were not given in the previous reports. The purpose of the present experiment is to study the structure, orientation, shape, size and distribution of sodium chloride deposits evaporated upon mica as a function of the substrate temperature.Sodium chloride was evaporated onto a freshly cleaved mica substrate heated at a temperature between 24° and 500°C in a vacuum of ∼ 1 × 10-4torr. Average thickness of the evaporated films was about 600Å. The specimens were divided into three parts. The first part was used for reflection electron diffraction observation. The reflection experiment was made using a specimen-charge neutralizer and for several different azimuthal positions of the deposits on the mica surface.
The Preparation of Electron Micrographs for Morphological Analysis of Carbon Black Primary Aggregates
Authors: Heckman F. A. , Medalia A. I. , Harling D. F. 
Published: June 2020

Recent electron microscope studies reveal that in most grades of black the so called “primary particles” are thoroughly fused together to form primary aggregates. The size and shape distribution of these aggregates is of great importance in that it affects the color properties of the black and the rheological properties of rubber or other materials in which it is dispersed.A new technique has been developed for characterizing size and shape distributions of primary aggregates of carbon black by computer analysis of electron micrographs.
Electron Microscopic Techniques for Fluorescent Lamp Phosphor Studies by Single Stage Replication
Authors: Walitsky Paul J. 
Published: June 2020

Electron Microscopy has long been utilized in the lamp industry for the study of tungsten and other lamp components. Little information has been published regarding the use of electron microscopy in the study of phosphors, a main component in fluorescent lamps. This study concerns calcium halophosphate phosphors, a primary component of fluorescent lamps.A modified single stage replica method similar to that of Munch has been adapted for use in the study of phosphors. The samples to be replicated were prepared by depositing the phosphor powder on a clean glass slide. Deposition was accomplished by a dry spray technique using low pressure Freon. A commercially available spray mounter can be utilized for this purpose. The critical parameter in the operation is pressure control, which when properly regulated promotes an even distribution of particles, and appears to facilitate subsequent removal of the evaporated film from the glass slide.
Preparation of Metal Foils by Mechanical Reduction
Authors: Carson K. R. 
Published: June 2020

Annealed and unannealed commercially available beaten foils were used for much of the very early transmission electron microscopy of metals. The studies were restricted to the few highly malleable metals, so, when electropolishing and chemical techniques were developed that permitted many other materials to be thinned as well, beating all but disappeared. It has been found, however, that mechanical reduction techniques provide a simple and rapid means to obtain electron transparent foils of a wide variety of metals and alloys.Tantalum, titanium, platinum, iron, permalloy, silicon-steel, brass, copper, aluminum, cadmium, tin, solder, and lead have all been beaten directly to foil simply by placing a small piece of the material on a polished steel flat and hammering with a steel mallet. The structures observed in the high melting point materials were characterized by high defect densities not unlike those found after explosive loading. Mechanical twins were observed in copper and platinum, and, in many cases structural evidence existed for localized adiabatic heating. Some of the low melting point materials investigated anneal at ambient temperatures and were observed in various stages of polygonization, recrystallization, and grain growth. Electron diffraction revealed a deformation texture in most materials.
Electron Microscopy of Superalloy Powders
Authors: Kotval P.S. , Dickey J.S. , Lewis B.E. 
Published: June 2020

Argon or water atomized alloy powders for use in powder-metallurgy parts usually have a particle size in the range 20-200µ. Because of this small size and the accompanying difficulty in specimen preparation, studies of metal powders have usually excluded transmission techniques and knowledge of the microstructure is confined to scanning electron microscopy studies.Fig. 1 shows a scanning electron micrograph of an argon-atomized particle of Haynes alloy 6B. It is clear that the particle is a spherical “microcasting” showing typical dendritic structure. When such particles are mounted and sectioned, the dendritic morphology is still observed (Fig. 2) indicating that there is a solidification structure throughout the particle and not just at the surface.
Application of Ion Pumps for Electron Microscopes
Authors: Maliakal J. C. 
Published: June 2020

Recently there has been much interest generated in improving the vacuum systems of Electron Microscopes and Electron Microprobes. Specimen contamination has been reported to be partly due to interaction of the electron beam and hydrocarbon molecules from poorly trapped oil diffusion pumps, organic gaskets, grease used on, gaskets, etc.Condensible vapors from the above contaminants in the specimen chamber also increase the contamination rate on the specimen. This paper reviews the methods available for an improved vacuum system for Electron microscope and other analytical instruments using oil free ionic vacuum pumps.
New Type High Voltage Generator
Authors: Ohta S. , Watanabe M. , Nakamura O. 
Published: June 2020

A high voltage generator has been developed with an extremely small ripple component by incorporating resistors in series in the filament transformer of the center-tapped Cockcroft Walton circuit. The rating of the prototype is 500 kV, and incorporates the following features, (See Fig. 1)1.The generator itself is perfectly symmetrical with respect to the output circuit.2.Stray capacitance (Cs) between the primary and secondary windings of the filament transformer can be reduced to negligible proportions.
Transmission Electron Microscopic Investigation of Pt-Si Thin Films
Authors: Anderson Ronald M. , Dash Somnath 
Published: June 2020

Recently, studies of platinum-silicon ohmic contacts in semiconductor device metallurgy have prompted us to make an investigation into the nature of the reaction between silicon and platinum. We confined ourselves to Pt deposition temperatures, annealing temperatures, and thicknesses that were germane to the production of ohmic contacts.Transmission electron microscopy, selected area electron diffraction, and reflection electron diffraction analysis, coordinated with x-ray diffraction studies, were performed and allowed us to make the following observations.
The Surface Structure of Mouse Heart Mitochondrial Membranes
Authors: Kreutziger G. Oscar 
Published: June 2020

The surface substructure of mouse heart mitochondrial membranes has been studied by freeze-etching. Eight different surfaces have been observed and identified. These are the sarcoplasmic interface, the outer and inner surfaces of the outer membrane, the lipid faces of the outer membrane, the intermembrane and matrix surface of the inner envelope, and the matrix interface.Freeze-etch replicas from glutaraldehyde fixed and glycerine cryoprotected mouse heart muscle were produced in a modified Bullivant-type simple freeze-etch device. The replicas were cleaned with “Clorox” and examined unsupported on 300 mesh grids in a Siemens Elimskop 1A.
The Composition of an Insect Sensory Nerve, The Cercal Nerve of the House Cricket Acheta Domesticus
Authors: Edwards John S. 
Published: June 2020

This report concerns aspects of cell number and diversity arising from a developmental study of an insect sensory nerve. The cereal nerve arises in the abdominal cercus, and terminates in the last abdominal ganglion, and forms part of the well known startle reflex.Tissues were fixed in 2% paraformaldehyde, 0.5% glutaraldehyde, Millonig phosphate buffer, pH 7.3 sectioned on a Sorvall Porter Blum MT2, stained with Reynold lead citrate and uranium acetate, and examined with an RCA EMU3G.
Ultrastructure of Granules Passing Through Frog Oocyte Nuclear Pores
Authors: Cole Madison B. 
Published: June 2020

Ovaries of Rana pipiens larvae were fixed in glutaraldehyde, post-fixed in osmium tetroxide, and embedded in epon. Thin sections of oocytes were routinely stained using methanolic uranyl acetate followed by lead citrate.The granule, designated M1, found in the primary oocytes is considered to pass through the nuclear pores by virtue of 1) its location in the nucleoplasm in close proximity to the nuclear envelope, 2) its contact with the nuclear pores, 3) its presence in aggregates in the perinuclear cytoplasm and A) its similarity to granules referred to by a number of authors (1-4) as material passing through nuclear pores.
A High-Resolution Scanning Microscope for Surface Studies
Authors: Hart R. K. 
Published: June 2020

There are a growing number of applications for high brightness electron optical systems which operate in non-contaminating “clean” residual gas atmospheres. These criteria are especially important if one wishes to look at, and characterize, surfaces for the purpose of following their behavior under rigorously-controlled conditions. Besides the obvious improvements to be gained in resolution and longer exposure to the electron beam, scanning electron microscopy can now be combined with other powerful techniques. These techniques include low energy electron diffraction (LEED), Auger electron spectroscopy (AES) and field emission retarding potential (FERP) studies of surface work functions.At one end of the electron optical column shown in Figure 1, which is only 20 cm long from source to specimen, a field emitting tungsten tip is used as the electron source, while at the other end of the column a four grid LEED/AES system has been affixed to the objective lens housing. The remainder of the column consists of a cylindrical magnetic lens, stigmator, and scanning coils. The residual gas pressure in the column during operation is <10-9 torr.
A New Color Display System for Scanning Transmission Microscopes
Authors: Crewe A. V. , Beck V. 
Published: June 2020

The most important aspect of the use of the scanning principle in high resolution transmission microscopy is that one can obtain separate electrical signals corresponding to the number of elastically and inelastically scattered electrons. A new display system has been constructed to take advantage of this quantitative information. This system has two independent functions: to display the picture produced by a scanning electron microscope and to interface the microscope to a computer.The color display system itself consists of a PEP-400 video-graphics storage terminal, a modified Zenith TV, and a video digital interface. The storage terminal is used as a scan converter and as storage for up to four pictures. It is possible to selectively erase portions of pictures stored in the terminal and then write new data into these regions. The storage terminal is thus a sort of random access memory. Information stored in the terminal will remain in storage for several days independent of whether the terminal's power is left on; however, a region can only be viewed for about five minutes, as the process of reading out a picture slowly destroys the picture.
A Calibration Method Usable in the Production of Phase Plates for High Resolution Electron Microscopy
Authors: Thon F. , Willasch D. 
Published: June 2020

It is well known that phase contrast in electron microscopy is normally due to the phase shift γ introduced by defocusing and spherical aberration of the objective lens. It is given by Scherzer's formula (2) :(1)where γ is the electron wavelength, Csthe spherical aberration coefficient, θ the diffraction angle and Δz the defocus value.However, in this way, only sections out of the spatial frequency spectrum contained in the abject are transferred to the image. In order to transmit the whole frequency spectrum, it has been proposed that a phase shifting plate is inserted into the back focal plane of the objective lens.
Applications of a Micro-Recording Device
Authors: Mueller K.-H. , Rindfleisch V. 
Published: June 2020

As described earlier the ELMISKOP 101 can be used as a very versatile micro-recorder. For this the cross-over of the electron gun is demagnified by the condensor system and the objective lens of the microscope (maximum demagnification 5000 x) Using the magnetic deflection system the minute probe can be shifted within the back focal plane of the objective lens. In this way contamination traces may be produced on a thin carbon foil.It is possible to drive the probe by an external electronic control unit with different programs. The control unit consists of a scanning generator to write gratings, point patterns and concentric circles to be used as calibration objects for the electron microscope, a flying spot scanner for the production of arbitrary halftone pictures and a unit with attached paper tape recorder.
Spatial Resolution of X-ray Analysis with Solid and Thin Specimens
Authors: Russ John C. 
Published: June 2020

The attachment of xray spectrometers, both wavelength and energy dispersive, to both scanning and transmission electron microscopes has provided the microscopist with the possibility of obtaining elemental analysis of features in the specimen that he can observe in the image. However, the volume of the specimen that emits xrays is in all cases larger than the image point he can observe in the highest resolution image with the microscope, and so he must use judgement to determine just how large a region is being analyzed.With a solid specimen in the SEM the situation is much like the conventional microprobe. Figure 1 shows the typical drop-shaped capture volume many times larger than the incident beam, and much deeper than the secondary electron source.