bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Cartilaginous Nature of the Cervine Antler
Authors: Banks William J. , Neal Jennifer 
Published: June 2020

The histomorphology and ossification process of the antler has been a subject of controversy. The exact nature of antler cartilage, based on light microscopic and limited histochemical analyses, has not been clarified. This report presents evidence that the ultrastructural features of antler progenitor cells and chondrocytes are similar to other cartilaginous systems which arise from reserve, undifferentiated cells.An extensive fibrocellular cap covered the distal portion of the growing antler and was continuous with the typical periosteum of the antler shaft and frontal bone. This hyperplastic tissue (Fig. 1) was composed of fibroblastlike cells which contained large nuclei with 1 or 2 nucleoli (N). The cytoplasm contained numerous free ribosomes and polyribosomes, as well as granular endoplasmic reticulum (ER). The latter was tubular or vesicular; some exhibited dilations.
Hepatic and Cardiac Changes in Protein-Deficient Rats
Authors: Zaki F. G. 
Published: June 2020

A kwashiorker-like experimental model has been studied in young growing Holtzman rats fed protein-deficient diet (4% alpha-soy-protein) for 6-20 weeks. The animals lost weight during the first three weeks, but became adapted to the protein-deficient diet and maintained practically constant weight thereafter.Hepatic lipid content progressively increased from 10% by the 6th week to about 20% after the 20th week. Deposition of hepatic lipid appeared initially in the periportal areas but gradually spread throughout the hepatic lobules. No fatty cysts nor fibrosis were encountered. Fatty degeneration was also noted in the cardiac muscle and the diaphragm.
Ultrastructural Changes in Patients With Heat Stroke
Authors: Minick O. T. , Kew M. C. 
Published: June 2020

The effects of heat stroke on hepatic structure were studied in 32 Bantu patients who worked underground in the Transvaal and Orange Free State Gold Mines.Judging from biochemical and morphologic findings, liver damage is an invariable complication of heat stroke. In the milder cases (90 per cent) raised enzyme levels, bromsulphalein retention, and increased prothrombin times were the most common abnormalities.
Single Atom Contrast in a Scanning Microscope
Authors: Crewe V. , Langmore J. , Wall J. , Beer M. 
Published: June 2020

The use of a scanning microscope offers unique opportunities in the way electrons penetrating a specimen can be Identified and collected.In particular, a number Ne will be elastically scattered by virtue of a total cross-section σe which is proportional to Z4/3. The angular distribution is such that most electrons are scattered outside the Illuminating cone which is incident on the specimen. In addition, a number Ni will be inelastically scattered this time by very small angles with a total cross-section σi which is proportional to Z1/3.
Studies of DNA Using a 5 å Scanning Microscope
Authors: Wall J. , Langmore J. 
Published: June 2020

One of the more important problems in electron microscopy has been the visualization of unstained DNA. Using the scanning microscope developed in the Crewe lab1 it is possible to see unstained DNA and to directly compare the observed contrast with that calculated from a simple incoherent scattering theory.The electrons passing through a 5 Å spot on the specimen can be conveniently separated into three groups--elastically scattered, inelastically scattered and unscattered. These groups are separated in space and can be simultaneously counted by independent detectors. In this way each 5 Å point on a square raster is measured sequentially. Table I shows calculated and measured intensities for various salts of double-stranded DNA on a 30 Å thick carbon film.
Ultrastructure of Atypical Spermatozoa in Colcemid-Treated Chinese Hamsters
Authors: Brinkley B. R. , Rattner J. B. , Gay Marion 
Published: June 2020

Colcemid, a derivative of colchicine, is well known for its capacity to inhibit microtubule formation in plant and animal cells. To determine the role of various microtubular systems such as the manchette, centrioles, and flagellar apparatus in mammalian spermiogenesis, adult male Chinese hamsters were injected daily with Colcemid at concentrations of from 6.5 x 10-5 M to 2.8 x 10-2 M. At various times following injections, the animals were sacrificed and testes and epidiymides were prepared for both light and electron microscopy.Concentrations greater than 2.7 x 10-4 M generally were lethal to animals within a period of 24 hours to 9 days. At lesser concentrations, animals survived normally without apparent ill effects.
Polymerizable Glutaraldehyde-Urea Mixtures as Water-Soluble Embedding Media
Authors: G. Peterson Richard , C. Pease Daniel 
Published: June 2020

Aldehyde-urea mixtures can be polymerized in the presence of substantial quantities of water. The components are highly polar. This provides an opportunity for preserving lipid structures in situ for ultrathin sectioning. Myelin retains its true periodicity (180Å) and integrity without osmication (1). Furthermore, the use of such embedding media permits superior preservation of highly hydrated structures, such as the glyco-calyx, which otherwise collapses.We have been preparing resin mixtures by adding appropriate amounts of urea to either 50%. (Fisher Co.) or 70% (Ladd Co.) glutaraldehyde, adjusted as necessary to pH ≃ 6. The proportion is not critical, but a 1: 1 molar ratio which provides equal numbers of aldehyde and amide groups polymerizes satisfactorily.
Use of the Magnetostatic Analogue In Electromagnetic Lens Engineering
Authors: Coleman John W. 
Published: June 2020

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force fields.
Thermal Recovery of Explosive-Shock Deformed Inconel 600 Alloy
Authors: Vydyanath H. R. , Murr L. E. 
Published: June 2020

Inconel specimens explosively shock-loaded to pressures of 80 and 460 Kb were annealed at temperatures of 700°C and 800°C for 1 hour, and the recovery of the shocked structures was followed by hardness, and electron microscopy observations.The initial (as-shocked) 80 Kb specimens were characterized by dense networks of dislocations with long dipoles, superjogs, etc., as shown in Fig. 1(a), whereas the as-shocked 460 Kb specimens were profusely twinned [Fig. 1(b)], the twin volume percent being 24%. The Vickers hardness numbers for the 80 and 460 Kb specimens were 265 VHN and 432 VHN respectively, an increase of 16% and 92% respectively with respect to their unshocked hardness values.
Oxidation of Single Crystal Iron Film at Very Low Pressures
Authors: Fan P. L. , Brockway L. O. 
Published: June 2020

The oxidation of iron has been studied mostly with polycrystalline samples and at advanced stages of oxide formation. The formation of isolated iron oxide grains on single crystal iron films has rarely been observed. This work is to report the observation, by transmission electron microscopy, of such oxide grains formed by controlled oxidation of single crystal iron films.Single crystal iron films were obtained by vapor deposition from an electron beam evaporator onto polished (001) faces of NaCl. The substrate, temperature was 350°C. The vacuum just before deposition was about 8 × 10−6 torr. The deposition rate was 8 - 10 A/sec and the thickness of the film was in the order of 1000 Å.
Variations in Surface Textures of Quartz Sand using Electron Microscopy
Authors: Amaral Eugene J. 
Published: June 2020

Examination of sand grain surfaces from early Paleozoic sandstones by electron microscopy reveals a variety of secondary effects caused by rock-forming processes after final deposition of the sand. Detailed studies were conducted on both coarse (≥0.71mm) and fine (=0.25mm) fractions of St. Peter Sandstone, a widespread sand deposit underlying much of the U.S. Central Interior and used in the glass industry because of its remarkably high silica purity.The very friable sandstone was disaggregated and sieved to obtain the two size fractions, and then cleaned by boiling in HCl to remove any iron impurities and rinsed in distilled water. The sand grains were then partially embedded by sprinkling them onto a glass slide coated with a thin tacky layer of latex. Direct platinum shadowed carbon replicas were made of the exposed sand grain surfaces, and were separated by dissolution of the silica in HF acid.
The Effect of Sulphur Impurity on the Crystallization of Calcite
Authors: Walker C. W. , Paulson G. G. 
Published: June 2020

Crystal morphology may be a key to understanding the mode of formation of the mineral calcite. Morphological features include crystal shape, crystal size, macrostructure and microstructure. To define these features, a combination of optical and electron microscopes were employed. An x-ray diffractometer and a x-ray spectrometer were used as supporting equipment.Samples were chosen on the basis of simplicity to exclude unforeseen variables such as clay or other accessory minerals which are often present in limestones. Such material was obtained from the calcite zone in the cap rock of the Minden Salt Dome, Webster Parish, Louisiana.The calcite consists of essentially two phases as determined by x-ray diffraction; the major phase CaCO3 and the minor phase, sulphur. There is an apparent relationship between the amount of sulphur present and calcite crystal size, shape, surface microstructure and often times color.
Embedding Procedure for Water Swollen Samples
Authors: Thomas Ann M. , Shemeley Virginia 
Published: June 2020

Those samples which swell rapidly when exposed to water are, at best, difficult to section for transmission electron microscopy. Some materials literally burst out of the embedding block with the first pass by the knife, and even the most rapid cutting cycle produces sections of limited value. Many ion exchange resins swell in water; some undergo irreversible structural changes when dried. We developed our embedding procedure to handle this type of sample, but it should be applicable to many materials that present similar sectioning difficulties.The purpose of our embedding procedure is to build up a cross-linking network throughout the sample, while it is in a water swollen state. Our procedure was suggested to us by the work of Rosenberg, where he mentioned the formation of a tridimensional structure by the polymerization of the GMA biproduct, triglycol dimethacrylate.
Nucleation and Early Growth of Sputtered thin Films
Authors: Sherman Dudley M. , Hutchinson Thos. E. 
Published: June 2020

The in situ electron microscope technique has been shown to be a powerful method for investigating the nucleation and growth of thin films formed by vacuum vapor deposition. The nucleation and early stages of growth of metal deposits formed by ion beam sputter-deposition are now being studied by the in situ technique.A duoplasmatron ion source and lens assembly has been attached to one side of the universal chamber of an RCA EMU-4 microscope and a sputtering target inserted into the chamber from the opposite side. The material to be deposited, in disc form, is bonded to the end of an electrically isolated copper rod that has provisions for target water cooling. The ion beam is normal to the microscope electron beam and the target is placed adjacent to the electron beam above the specimen hot stage, as shown in Figure 1.
A Preparation of High Resolution Standards for Electron Microscopy - Part 1
Authors: Tanaka Akira 
Published: June 2020

One of the means of Gemonstrating the resolving power of the electron microscope is to use the lattice image of vacuum evaporated thin single crystals. Although the technique for obtaining such single crystal films has been reported, there are many difficulties in practice, including the requirement for special vacuum evaporation equipment and highly sophisticated procedures.This paper describes the method of obtaining single crystal films in a relatively short time. A simplified vacuum depositing unit will be described in detail as well as optimum temperatures and conditions for the substrate, annealing and controlling of the film thickness. A few examples will also be presented.
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.
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.
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.
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.
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).
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.