bluuebunny/crossref_metadata_2025_split huggingface dataset:
High resolution observations of short-range ordering in disordered Au4Mn alloys
Authors: Tanaka Nobuo , Ohshima Ken-ichi , Harada Jinpei , Cowley J.M. 
Published: June 2020

Observation of short range ordered (SRO) state in disordered binary alloys is the interesting topic in the point of order-disorder transition. The observation and analysis have been made with X-ray and neutron diffraction techniques which can give the SRO-parameters. These techniques, however, give only the information of an averaged structure. The ordering process is localized, so direct observations in atomic level by high resolution electron microscopy is needed for the detailed analysis.In the present study, disordered Au4Mn alloys were investigated with high resolution electron microscopy for the analysis of the origin of the characteristic SRO diffuse scattering (Fig. 1). The material was prepared by quenching and thinned by electrolytic polishing for microscopic observations. The specimen was observed along <120> direction by JEOL-200CX electron microscope (E=200keV).
High-resolution electron microscopy of disordered LiFeO2
Authors: Tanaka Nobuo , Cowley J.M. 
Published: June 2020

The disordered structure of lithium ferrite (α-LiFeO2) has been investigated in X-ray and electron diffraction techniques. The characteristic short range order (SRO) diffuse scattering was commonly interpreted by the clustering model. The SRO state can be described by interconnecting two kinds of clusters (Fig. 1). Alternatively, it may be interpreted in terms of microdomains of some ordered structures.In the present study, the specimen was investigated with high resolution electron microscopy and optical diffraction technique. The techniquescould give the information about the SRO state in a direct way. The material investigated was α-LiFeO2in the form of a fine powder dispersed on a holey carbon grid.Fig. 2 shows electron diffraction patterns of the specimen in the <001> and <110> observing directions. The locus of the diffuse scattering does not exactly fit with the formula, cosπh + cosπk + cosπℓ = 0, which was derived from SRO arrangement of Li and Fe ions inside the clusters. This fact suggests the existance of “inter-cluster” ordering.
The response to heating of dislocation structures in zircaloy-2 irradiated to high neutron fluences
Authors: Gilbert R.W. 
Published: June 2020

Zirconium alloys have good neutron economy and corrosion resistance in high temperature water and this has led to extensive usage of these alloys in CANDU reactors. However, during neutron irradiation, dimensional changes occur in zirconium components due to the rearrangement of atoms knocked from their lattice sites by fast neutrons. This “irradiation growth” may limit the lifetime of some reactor components and an understanding of the variables that control the process is of commercial importance.It is believed that dislocations and dislocation loops act as sinks for the displaced atoms and thus control the direction and magnitude of the strain through their Burgers vector. A knowledge of the irradiation-induced dislocation structure is therefore required.
The effect of different depths in the foil on the image contrast of dispersed precipitates
Authors: Hu C.T. , Allen C.W. 
Published: June 2020

The precipitate particles with similar size are often observed to exhibit quite different contrast in a dark-field TEM micrograph, as shown in Figure 1. The accuracy of particle size determination will be influenced by this variation of contrast. In order to faithfully determine the diameter of second phase precipitates, the causes of this different contrast needed to be investigated. The change of image contrast due to the relaxation of coherency strain of precipitates has been discussed in other work. This study try to found out the influence on the image contrast by the different particle depths in the foil as well as by the interference with the surface oxide.If the differing contrast of similar size particles is caused by the different particle depths in the foil, then the change of relative depths by straight inverting the specimen and imaging under the same diffraction condition would cause the variation of the particle image contrasts.
Characterization of oxide scales on complex alloys using multiple microanalytical techniques
Authors: Sprague J. A. , Singer I. L. , Gossett C. R. 
Published: June 2020

The alloys used as coatings to protect gas turbine components from high temperature oxidation and from sulfur-related hot corrosion attack are, in most cases, complex multiphase materials, which form complex oxide scales. A study of the effects of alloy composition and microstructure on the mechanisms controlling oxidation of such a system is greatly aided by the use of complimentary information from several microanalytical methods, each of which has its own strengths and weaknesses.In investigations of oxide scales, scanning Auger microanalysis (SAM), in conjunction with Ar-ion milling gives semiquantitative composition vs. sputtering time for each of the phases detected. However, since various metals and their oxides can sputter at different rates, only relative depth scales can be obtained. Rutherford backscattering spectroscopy (RBS), on the other hand, provides absolute depth scales and quantitative composition information for the heavier elements in the specimens.
Inexact reconstruction: A. The basic method
Authors: Crewe A. V. , Crewe David A. 
Published: June 2020

The problem of reconstructing a 3D object from its 2D projections is too well known to require much introduction. Great success has been achieved in a few special cases and in electron microscopy we can refer to the use of regular arrays of molecules or the use of isolated objects having a great deal of internal symmetry, while the case of the generalized object is exemplified by the CAT scan system. Unfortunately this last method is not suitable for electron microscopy because of the large number of projections which would be required.If we imagine a small object contained inside a cube of N3 resolution elements it would normally require N views containing N2 line projections in order to have enough information for a reconstruction. However, if we make the reasonable assumption that the object is Boolean in nature—by which we mean that it has a uniform density—then the number of required projections decreases considerably.
Formation of single-layer arrays and 6-Angstrom electron imaging of the surface layer protein of Aquaspirillum serpens
Authors: Wu W. H. 
Published: June 2020

Aquaspirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits (HP-protein). Buckmire and Murray concluded that a “backing layer”, later identified to be the outer membrane, was required for HP-protein to form 2-d arrays.We developed a modified procedure of isolation of outer wall fragments. The yield was about 10 times increased, and patches with structured arrays were bigger and more frequent. Large, light arrays of good crystalline order were obtained, with which the optical diffraction patterns always show “handedness” (see Fig. 1); whereas with the dark patches, the optical diffraction patterns appear to be symmetrical. We conclude that the light arrays are real single layer protein arrays.
Evidence of an helicoidal symmetry for rubella virus nucleocapsid
Authors: Alain R. , Berthiaume L. , Trudel M. 
Published: June 2020

Rubella virus is presently the only member of the genus Rubivirus of the Togaviridae family (Matthews, 1982). One of the main characteristics of this family is that the symmetry of the nucleocapside is cubical. Electron microscopy shows that rubella virus is a small spherical enveloped particle, 50 to 100 nm in diameter, with a dense core measuring 28 to 30 nm in diameter. Payment et al., in 1975, reported that the core structures are composed of circular subunit, 10 nm in diameter. Morphogenetic studies reveal that core formation coincides with the process of budding (Murphy, 1981).Rubella virus is composed of three structural proteins E1 (60K), E2 (47K.) and C (33K): E1 and E2 are membrane glycoproteins while C is the nucleoprotein (Trudel et al., 1982). The genome of the virus is a single standed positive RNA.Upon examination of purified rubella virus by electron microscope, beside whole virus particles we observed in all preparations helicoidal nucleocapsids of variable lenghts, ranging from a few nanometers to as long as 265 nm (Fig. 1). The width of these was evaluated to about 14.7 + 0.9 nm with a helix pitch of 10 nm. They were flexible and fragile, showing rapid denaturation when viral suspensions were kept at room temperature for a few hours.
Electron Microscopy of Porous Silicon Films
Authors: Anderson R. M. , Aboaf J. , Cameron D. P. 
Published: June 2020

Thick thermal oxide films on Si are usually obtained by oxidation at high temperatures; e. g., 1 μm of thermal oxide is obtained at 1000°C after 5 hr in water vapor. Such a long oxidation step is unattractive from a Si processing viewpoint; also, defects have been observed to occur in wafers subjected to such a procedure. A porous Si film may be comparably oxidized in 3 to 4 min.Porous Si is obtained by anodizing Si in HF solution. The growth and porosity of the porous layer depend on the type and resistivity of the Si, HF concentration, and anodizing time. Microstructural characterization shows that “pores” in Si, depending on conditions, vary from a few tens of angstroms to microns.
The Initial Epitaxy of Copper on (111) Gold Single Crystals
Authors: Macur J. E. 
Published: June 2020

Two of the primary requirements needed for a successful study of epitaxy are a contamination free environment (UHV) and an extremely smooth, clean substrate surface. The deposition should be studied in situ by means of some surface sensitive technique (e.g. RHEED or LEED) and then in TEM and TED. Such a study has been conducted with Cu on (111) Au.Extremely smooth (111) single crystals of Au were evaporated on NaCl/mica in a UHV-RHEED system whose base pressure was 7 x 10-10 torr. After a 15 minute anneal at 625°C the films were cooled to room temperature. The initial growth of Cu on (111) Au at room temperature was studied is the following manner. Fractions of a monolayer of Cu were deposited (~1A per minute) onto the Au substrate and immediately examined in RHEED.
A New High Resolution STEM for Biological Studies
Authors: Bittner J. W. , Wall J. S. 
Published: June 2020

A new high resolution scanning transmission electron microscope (STEM) has been constructed in the Biology Department at Brookhaven National Laboratory. The microscope will be operated under the NIH National Research Resource Program and will be open to outside users as well as Brookhaven staff.Since the primary goal of the facility is biological research rather than instrument development, careful attention has been paid to designing an instrument which will be easy to use, reliable, and easy to service, without sacrificing high performance. The electron gun is copied from one of the Chicago designs and operates at 100 KeV with the field emission source at room temperature in a vacuum better than 10-10 Torr.
A Simple Transmission Stage for a Scanning Electron Microscope
Authors: Lin P. S. D. , Lamvik M. K. 
Published: June 2020

Unlike a CEM or high resolution STEM, where the specimen is immersed between the pole pieces of the objective lens, a scanning electron microscope has its specimen stage situated off the lens field. After scattering with the specimen, electrons follow straight paths. It is rather simple to deduce the information from the signal. A transmission stage in a SEM is therefore a useful device for studying various scattering processes and the contrast thus generated.The transmission stage can also be used in connection with the investigation of secondary and backscattered electron emission phenomena. Previously, a back-scattered electron detector was installed in one of the scanning microscopes in the laboratory.
Applications of Through-Focus Dark Field Image Shifts to Phase Identification
Authors: Rao Prakash 
Published: June 2020

Image shifts in out-of-focus dark field images have been used in the past to determine, for example, epitaxial relationships in thin films. A recent extension of the use of dark field image shifts has been to out-of-focus images in conjunction with stereoviewing to produce an artificial stereo image effect. The technique, called through-focus dark field electron microscopy or 2-1/2D microscopy, basically involves obtaining two beam-tilted dark field images such that one is slightly over-focus and the other slightly under-focus, followed by examination of the two images through a conventional stereoviewer. The elevation differences so produced are usually unrelated to object positions in the thin foil and no specimen tilting is required.In order to produce this artificial stereo effect for the purpose of phase separation and identification, it is first necessary to select a region of the diffraction pattern containing more than just one discrete spot, with the objective aperture.
Classical Transport Theory and the Imaging of Thick Specimens
Authors: Groves T. 
Published: June 2020

It is common in transmission electron microscopy to use specimens which are of the order of a micron in thickness. For such thicknesses it becomes likely that an incident electron will scatter more than once, and one would expect some drastic effects on image formation. A theory of image formation has been derived for thick specimens in the conventional (CEM) and scanning transmission (STEM) electron microscopes. This theory is based on a solution of the Boltzmann transport equation for plural scattering, and is expected to apply to the imaging of small objects embedded in thick amorphous films.We imagine an idealized specimen shown in Fig. 1. A point-like object is embedded in a thick film at a depth n1, measured in units of the mean free path λ for elastic scattering.
Electron Energy Loss Microanalysis of an Internally Oxidised Ni-Al Alloy
Authors: Ditchfield R W , Fourdeux A , Whelan M J 
Published: June 2020

A good strength, high temperature Ni-Al alloy had been produced by thermomechanically cycling sintered aluminium and nickel powders. The microstructure of the alloy consisted of a solid solution in which there was a fine dispersion of inert ceramic particles. A typical micrograph is shown in Fig 1 in which three distinct types of particle A, B and C are indicated. To explain the mechanical properties of the alloy it was necessary to determine the composition and structure of the particles.As the particles were 300Å to 1200Å in size the only satisfactory method to use was combined electron microscopy and energy analysis. Thinned foils containing unobscured particles were used so that, by placing slit of the Mollenstedt analyser across it, the energy loss spectrum of each particle was measured directly.
Surfactant Bodies: The New Look o£ the Lamellar Inclusions from Type II Alveolar Pneumocytes
Authors: Wagner R. M. , Miyai K. 
Published: June 2020

Lamellar bodies, inclusions unique to type II alveolar cells, have an essential role in the metabolism of the surface-active lipoproteins of the mammalian lung. Most recent investigations have shown that the type II alveolar cell also functions as a progenitor of alveolar epithelial regeneration in certain types of alveolar injury, thus emphasizing the need for complete characterization of this cell and its lamellar inclusions. This paper presents a new appearance for the lamellar inclusion in situ as well as in isolated fraction and suggests a correlation between the improved appearance and the biochemical composition of the inclusion.The lungs from adult male rats were removed and 1 mm3 blocks were cut from the peripheral lung regions for the in situ studies. This tissue was fixed in 1% OSO4 in 0.15 M isotonic buffered saline at 4°C for 2 hours then dehydrated with a graded series of acetone at 4°C and embedded in Luft's Epon.
Middle Cerebral Artery Response Following Occlusion with a Surgical Clamp
Authors: Dodson Ronald F. , Tagashira Yukio , Chu Lena W.F. , Scates Ronald W. 
Published: June 2020

One of the most consistently reproducible models for studying experimentally induced cerebral infarction in animals has been through surgical occlusion (clamping) of the middle cerebral artery (MCA). The resultant morphological, hemodynamic, and metabolic changes in brain tissue mimic those which occur in man following stroke. Although numerous reports exist which have incorporated this model in their study of ischemic effects on the brain, a void of information exists as to the morphological response of the vessel and its associated nerve bundles following the application of the clip.Adult squirrel monkeys used in this investigation were subjected to transorbital occlusion at the M-l segment of the right middle cerebral artery for respective periods of either 1/2, 1,2,3 or 4 hrs. At the end of the selected time period, the clip was removed and the animals were subjected to whole body perfusion with 500 ml of 3% glutaraldehyde in 0.1 M phosphate buffer.
Fine Structural Analysis of Muscle Degeneration Caused by Amyloid Infiltration
Authors: Rodgers O. G. , Shirahama T. , Cohen A.S. 
Published: June 2020

Amyloidosis, especially the primary type, often causes myopathies including heart failure. These myopathies are believed to be secondary to the infiltration of amyloid around and into the muscle cells. However no detailed ultrastructural study has been available on this subject in either skeletal or cardiac muscle.The intrinsic muscle ultrastructure of tongue obtained at hemiglossectomy from two patients with systemic primary amyloidosis with macroglossia were studied. The results were analysed to assess the process of muscle atrophy caused by infiltration of the amyloid fibrils.The atrophic process can be classified into five phases. 1) In the area free of and remote from the amyloid deposition muscle ultrastructure was normal (Fig. 1). 2) While larger amounts of amyloid fibrils were deposited around the muscle cells, amyloid fibrils were also found in the muscle cells forming relatively large islands or in small amounts among the myofibrils.
Nonvolatile Octavalent Osmium Compounds as Sources of Osmium Tetroxide for Electron Microscopic Cytochemistry
Authors: Hanker J. S. , Romanovicz D. K. , Crenshaw M. A. 
Published: June 2020

A number of compounds of osmiumVIII including osmiamates and coordination complexes of OsO4 with various heterocyclic nitrogen compounds have been synthesized, characterized and evaluated as substitutes for OSO4 in cytochemistry. The compounds synthesized include ammonium osmiamate (NH4OsO3N), potassium osmiamate (KOSO3N), and addition complexes of OSO4 with hexamethylenetetramine, pyridine, quinoline, piperazine, and sym. collidine.The ammonium osmiamate was relatively unstable. The potassium osmiamate, although stable, was insoluble. Pyridine formed a stable yellow complex with OsO4 which was insoluble in water and sublimed readily at room temperature. All of the other nitrogen heterocycles formed unstable molecular addition complexes which decomposed in a short period of time with the exception of hexamethylenetetramine. The latter formed a stable complex, which had a negligible vapor pressure of OSO4, and did not sublime like many of the other octavalent osmium compounds. Spectroscopic studies, potentiometric titration,elemental analysis, and atomic absorption studies with an osmium lamp indicated the structure shown in Fig. 1 (top).
Mitochondrial Oxidation of p-N, N-Dimethylamino-β-Phenethylamine (DAPA)
Authors: Allen Shannon W. , Wasserkrug Hannah L. , Seligman andArnold M. 
Published: June 2020

The synthesis of a new substrate, p-N,N-dimethylamino-β-phenethylamine (DAPA)3 (Fig. 1) (1,2), and the testing of it as a possible substrate for tissue amine oxidase activity have resulted in the ultracytochemical localization of enzyme oxidase activity referred to as DAPA oxidase (DAPAO). DAPA was designed with the goal of providing an amine that would yield on oxidation a stronger reducing aldehyde than does tryptamine in the histochemical demonstration of monoamine oxidase (MAO) with tetrazolium salts.Ultracytochemical preparations of guinea pig heart, liver and kidney and rat heart and liver were studied. Guinea pig kidney, known to exhibit high levels of MAO, appeared the most reactive of the tissues studied. DAPAO reaction product appears primarily in mitochondrial outer compartments and cristae (Figs. 2-4). Reaction product is also localized in endoplasmic reticulum, cytoplasmic vacuoles and nuclear envelopes (Figs. 2 and 3) and in the sarcoplasmic reticulum of heart.
The Basal Apparatus of Bovine Retinal Rods
Authors: Raveed Dan , Fleischman Darrell 
Published: June 2020

Several types of mammalian sensory receptor cells possess modified cilia which may play a primary role in stimulus detection. Axonemes and basal apparatus from other types of cilia and flagella have been isolated, characterized and compared in detail. In this communication we report results of what may be the first attempt to isolate and characterize such structures from a sensory cilium, the bovine retinal rod outer segment.Bovine eyes were obtained from a nearby abattoir, the retinas were removed and swirled vigorously in a cold solution of 50% sucrose, 5 mM Tris, 2 mM MgCl2, pH 7.5, to detach outer segments. The suspension was then filtered through cheesecloth and the filtrate was centrifuged at 20,000 rpm for 1 hr. Rod outer segments were collected from the solution surface, diluted, layered onto a continuous sucrose gradient (25-38% sucrose in Tris MgCl2 buffer) and centrifuged for 3-12 hrs. at 10,000 rpm.
Direct Visualization of the Hydrophobic Portion of Acholeoplasma Laidlawii Membranes
Authors: Heckman C. A. , Barrnett R.J. 
Published: June 2020

Alteration and extraction of lipids occur during the preparation of biological tissues for electron microscopy. This problem has rendered the interpretation of membrane fine structure in molecular terms particularly difficult. By using a water-miscible, glutaraldehyde-carbohydrazide (GACH) resin polymerized at neutral pH, we have previously demonstrated lipid retention in biological tissues during embedding. Since A. laidlawii membranes have been characterized with regard to the composition and structural organization of the lipid component, they provided an ideal model system for direct visualization of the retained lipids after GACH embedding.High resolution micrographs of the membranes were taken on a Hitachi HU-11B electron microscope. At the same time, the instrument was calibrated according to established guidelines and found to give a standard deviation of 2.9% in magnification over a period of approximately one year. A. laidlawii strain B cells were generously provided by Dr. James Gilliam. The presence of an intact, hydrophobic core in sections of GACH-embedded membranes was confirmed by vanatomolybdate staining of the thin sections.
The Identification of Phospholipid Micelles in Glutaraldehyde-Urea Embedded Tissue
Authors: Pease Daniel C. 
Published: June 2020

It is reasonable to think that phospholipid micelles should be visible and identifiable in electron micrographs of ultrathin sections if only they can be preserved throughout the embedding process. The development of highly polar, water-containing, aminoplastic embedments has made this a likely possibility. With this in mind, an investigation of the lecithin-secreting, Type II pneumocytes of the lung is underway.Initially it has been easiest to recognize phospholipid micelles in lung tissue fixed first with glutaraldehyde, and then secondarily exposed to osmium tetroxide. However, the latter is not a necessary concomitant for micellar preservation. Conventional uranyl acetate and lead citrate staining is finally applied. Importantly, though, the micelles have been most easily seen in tissue embedded in 507. glutaraldehyde polymerized with urea, as described in detail by D.C. Pease and R.G. Peterson (J. Ultra- struct. Res., 41, 133, 1972).
When oriented appropriately, the micellar units are seen as tiny, bilayer plates.