bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microstructure of Electro-Eroded Cemented Carbide Surfaces
Authors: Filimonenko V. N. , Richman M. H. , Gurland J. 
Published: June 2020

The high temperatures and pressures that are found in a spark gap during electrical discharging lead to a sharp phase transition and structural transformation in the surface layer of cemented carbides containing WC and cobalt. By means of X-ray diffraction both W2C and a high-temperature monocarbide of tungsten (face-centered cubic) were detected after electro-erosion. The W2C forms as a result of the peritectic reaction, WC → W2C+C. The existence and amount of the phases depend on both the energy of the electro-spark discharge and the cobalt content. In the case of a low-energy discharge (i.e. C=0.01μF, V = 300v), WC(f.c.c.) is generally formed in the surface layer. However, at high energies, (e.g. C=30μF, V = 300v), W2C is formed at the surface in preference to the monocarbide. The phase transformations in the surface layer are retarded by the presence of larger percentages of cobalt.Metallographic examination of the electro-eroded surfaces of cemented carbides was carried out on samples with 5-30% cobalt content. The specimens were first metallographically polished using diamond paste and standard procedures and then subjected to various electrical discharges on a Servomet spark machining device. The samples were then repolished and etched in a 3% NH4OH electrolyte at -0.5 amp/cm2. Two stage plastic-carbon replicas were then made and shadowed with chromium at 27°.
The Application of Ultra-Thin Sectioning Techniques to Non-Biological Samples
Authors: Oster C. F. 
Published: June 2020

Although ultra-thin sectioning techniques are widely used in the biological sciences, their applications are somewhat less popular but very useful in industrial applications. This presentation will review several specific applications where ultra-thin sectioning techniques have proven invaluable.The preparation of samples for sectioning usually involves embedding in an epoxy resin. Araldite 6005 Resin and Hardener are mixed so that the hardness of the embedding medium matches that of the sample to reduce any distortion of the sample during the sectioning process. No dehydration series are needed to prepare our usual samples for embedding, but some types require hardening and staining steps. The embedded samples are sectioned with either a prototype of a Porter-Blum Microtome or an LKB Ultrotome III. Both instruments are equipped with diamond knives.In the study of photographic film, the distribution of the developed silver particles through the layer is important to the image tone and/or scattering power. Also, the morphology of the developed silver is an important factor, and cross sections will show this structure.
High Resolution Replication of Metallic Microcrystals
Authors: Bottoms W. R. , Morriss R. H. 
Published: June 2020

Bradley's well known direct carbon replication technique with Pt-C shadowing offers the best resolution of any method currently in use. In the present study variations of this technique were applied to a system of gold microcrystals in an effort to obtain replicas of the highest possible resolution. Crystals with diameter on the order of 1000Å and thickness ∼100 Å have been examined for surface defects which might effect the growth process. This requires replication with higher resolution than is normally obtained.The basic technique consists of evaporating a suspension of the particles onto a clean glass slide, depositing 100-200 angstroms of carbon by vacuum evaporation, floating the carbon film on a solvent to remove the particles, and mounting the replica on support grids for shadowing. The factors limiting the resolution of the replica are:The accuracy in the reproduction of the surface topography by the carbon film.“Pile-up” effects due to the physical thickness of the carbon and Pt-C in the shadowing direction.Contamination of the specimen and replica surfaces by a layer of hydrocarbons.Granularity of the shadowing material.
The Materials Analysis Company Model 700 Scanning Electron Microscope
Authors: Macres V.G. , Preston O. , Yew N.C. , Buchanan R. 
Published: June 2020

The Model 700 scanning electron microscope is a high resolution instrument which incorporates the same basic modular concept that has proven so satisfactory in the Materials Analysis Company Model 400 x-ray microprobe and its latest development, the Model 400S. The instrument described here is the basic building block to which accessories such as additional display tubes, special specimen holders, etc., can be easily added.The electron-optical column consists of a triode electron gun, double electromagnetic condenser lens, and objective lens. A .004″ tungsten hairpin filament is used as the electron source, and the filament to grid spacing is externally adjustable during operation to optimize gun performance for all operating conditions. The double condenser system is unitized and uses a single energizing coil. An adjustable multiple aperture holder is provided between the double condenser lens system and the objective lens, which serves to define the convergence angle of the probe in the specimen plane.
Transmission Electron Cinephotography of Aℓ Films During Passage of Electrical Current
Authors: Blech I. A. , Meieran E. S. 
Published: June 2020

Mass transport has been observed in metals conducting direct current. The atom flux can be toward either the anode or the cathode, depending on the conductor material. For Aℓ wires, it was found that the Aℓ atoms migrated from the cathode to the anode, apparently due to momentum transfer from the electrons to the atoms.This mass transport was directly observed during current passage through Aℓ strips by transmission electron microscopy, using a specially constructed sample holder for the Hitachi HU-11 electron microscope and an appropriate sample. The samples were made by evaporating a thin Aℓ film onto an 0.010 inch thick Si wafer coated with 1000Å of SiO2- The Aℓ film was etched into the pattern shown schematically in Fig. 1 by normal photoresist techniques.
Epitaxial Copper Films Evaporated in Ultra-High Vacuum
Authors: Shimaoka G. , Lane J. W. 
Published: June 2020

Recent electron microscopy and diffraction studies of vacuum-deposited films have demonstrated the importance of temperature and surface condition of substrate in determining film structure and growth. Many interesting results of thin epitaxial films of face-centered cubic metals such as gold and silver have been reported. But, relatively few studies of copper have been made. The purpose of this study is to investigate structure and epitaxy of copper thin films evaporated onto various single-crystal substrates in an ultra-high vacuum.High purity copper was evaporated onto freshly cleaved (0001)MoS2, (100)NaC1, (001)mica and (11)CaF2 surfaces heated at temperatures between ∼25° and 200°C in a vacuum of ∼10-8 Torr. Average thickness of deposited films was about 90 Å. Deposition rate was about 0.4 Å/sec. The films were studied by reflection electron diffraction and transmission electron microscopy. Oxidation of copper films during preparation for electron microscopy and diffraction observation was minimized by deposition of thin layer of amorphous carbon upon freshly formed copper films.
Structure of CdS Films Deposited on Single-Crystal Substrates
Authors: Shimaoka G. 
Published: June 2020

Recent X-ray or electron diffraction studies of CdS films vacuum-deposited on single-crystal substrates, such as mica, rock salt, etc., have demonstrated a marked effect of the substrate on the structure and orientation of the deposited films, particularly Escoffery has reported that cubic CdS (zinc-blende type) could be produced on molybdenum foil heated at 175°C. The purpose of this study is to investigate structure and orientation of thin CdS films evaporated onto various single-crystal substrates having hexagonal or cubic structure as a function of substrate temperature and to find optimum epitaxial growth condition.Single-crystal CdS (hexagonal, wurtzite type) was evaporated onto freshly cleaved (0001) MoS2, (111) CaF2 and (100) NaCl surfaces heated at various temperatures between ∼25° and 500°C in a vacuum of about 5 x 10-5 Torr. Average thickness of the deposited films was about 100Å. The rate of deposition was about 2Å/sec. The deposited films were examined by three different methods: a) reflection electron diffraction, b) high-resolution transmission electron diffraction and c) transmission electron microscopy and selected-area electron diffraction.
Etching of Polymers by Oxygen Plasma
Authors: Peck Virgil , Carter W. L. 
Published: June 2020

Any electron microscopical study of the morphology of bulk polymers has throughout the years been hampered by the lack of any real ability to produce meaningful surface variations for replication. True etching of polymers should show crystalline and amorphous regions in some form of relief. The use of solvents, acids, organic vapors, and inert ion bombardment to etch samples has proved to be useful only in limited applications. Certainly many interpretations of these results are subject to question.The recent use of a radiofrequency (R. F.) plasma of oxygen to degrade and remove organic material with only minor heating has opened a new possibility for etching polymers. However, rigid control of oxygen flow, time, current, and sample position are necessary in order to obtain reproducible results. The action is confined to surface layers; the molecular weight of the polymer residue after heavy etching is the same as the molecular weight of the polymer before attack, within the accuracy of measurement.
Fractography of Polytetrafluorethylene (PTFE)
Authors: Nerren Billy H. 
Published: June 2020

The need to know how and why materials fail is increasing each year. It is universally known and accepted that failure modes of metals can be determined by studying the topography of the fracture surfaces. The need for understanding failures of non-metals has recently been dramatized by the failure of a PTFE seal in a Saturn V LOX fill and drain valve that resulted in a liquid oxygen leak. In an effort to bridge this gap in our knowledge, a study was designed to determine the applicability of fractographic analysis to non-metals, in particular, to PTFE.Initial work was performed using both the direct carbon and the two stage acetate replication techniques. However, the two stage acetate replica technique was later selected for all work because of the difficulty in removing a direct replica from PTFE.
Initial Stages of the Oxidation of Tantalum
Authors: Geiss R. H. , Lawless K. R. 
Published: June 2020

Pre-thinned high purity tantalum sheet was oxidized in high purity oxygen at 500°C in an ultra high vacuum reactor vessel at pressures of 10 to 100 microns for 30 to 90 minutes. Transmission electron microscopy revealed changes in the microstructure as the oxidation progressed and electron diffraction showed many different sub-oxide phases and marked ordering effects.For the lowest oxygen exposure, 10 microns for 30 minutes, a microstructure showing both large and small domains was found, Figure 1. As can be seen the size and shape of the domains varied considerably. The long narrow domains are near the edge of the foil and all have boundaries along ﹛100﹜ In intermediate regions, about one micron in from the edge, the domains have a peculiar “air plane” shape with boundaries along both ﹛100﹜ and ﹛110﹜ and “wings” adjacent to the ﹛100﹜ boundary. Interspaced among the airplane shaped domains and in regions up to 3 microns from the edge are very small, interconnected nuclei.
Moire Fringes in Alpha Plates Within a Beta Titanium Alloy
Authors: Banerjee Bani R. 
Published: June 2020

When the beta phase isothermally transforms to alpha upon aging, the lenticular alpha precipitate frequently exhibits fine parallel markings, as shown in Figure 1, but the nature of the markings remains unexplained, although microtwins and oxide epitaxy have been suggested. Therefore, 25μ thick foil specimens of the alloy (14.0V, 11.5 Cr, 3.2 Al, bal Ti) were solution annealed 1/4 hr. at 788C, and aged 24 and 72 hr. respectively at 482C — using a predessicated Argon atmosphere. The heat-treated foils were electrolytically thinned in a 6% perchloric acid, 59% methanol, 35% ethylene glycol monobutyl ether electrolyte, at 15-18 volts, using a Bollmann electrode arrangement.Because of the absence of twin reflections and the lack of evidence of an oxide film by electron diffraction from foils exhibiting parallel markings in the alpha plates (Figure 1), the markings were suspected to be Moiré fringes produced by double diffraction from the alpha precipitate and the beta matrix respectively.
The Reaction of Carbon Black and Thoria
Authors: Mercer H. N. 
Published: June 2020

As a result of a reported “dispersal of carbon black to individual crystallites” by K. J. Notz, we decided to investigate this phenomenon. We have observed a somewhat different reaction in that portions of the carbon particles are removed instead of complete breakdown to individual crystallites.Carbon black is particulate matter composed almost entirely of carbon. The particles are somewhat spherical and fuse together during manufacture to form chains of varying length. These particles and chains retain their same shape during most reactions and when incorporated into rubber. Oxidative attack on normal furnace blacks occurs from the inside out due probably to more random orientation of the crystallites at the center of a particle. Many chemical reactions of the functional groups at the surface of the carbon particle are also known. The observation that the simple mixing of carbon black with finely divided thoria removes only a portion of the particle, constitutes a new type of carbon black reaction.
Contributions of ultrastructural cytochemistry to the analysis of stimlus-response patterns in neutrophils
Authors: Karnovsky M. J. 
Published: June 2020

Upon stimulation neutrophils undergo a complex series of biochemical and morphological changes. Phagocytosis by polymorphonuclear leukocytes (PMN) is accompanied by enhanced cyanide-insensitive respiration and hexose monophosphate shunt activity. H2O2 and O2 free radicals, such as superoxide O2-, are produced in increased amounts. H2O2, myeloperoxidase, and halide ions constitute a potent microbicidal system (Klebanoff system), via halogenation, e.g., chlorination, of microorganisms. Intermediate reaction products of oxidation, e.g., aldehydes, might themselves be microbicidal, or act as substrates for further H2O2 production. We have examined these aspects of phagocytosis with specially developed techniques of oxidative cytochemistry and correlated cytochemical, biochemical, and functional data.Utilizing diaminobenzidine (DAB) as a substrate for myeloperoxidase, we were able to confirm, at the EM level, that myeloperoxidase, present in the azurophil granules, enters the phagosome upon degranulation. We also showed, using a modified DAB reaction, that endogenous H2O2 was present in the phagosome. Intracellular halide, probably chloride, is presumed to be freely available.
Three-dimensional reconstruction studies of mitotic spindle ultrastructure
Authors: Rieder C.L. , Rupp G. , Alexander S.P. , Nicklas R.B. 
Published: June 2020

The mitotic spindle is composed chiefly of microtubules (MTs) and functions to equally distribute the replicated chromosomes to daughter cells. Spindles are generated from an interaction between the spindle poles and kinetochores. The former are responsible for generating spindle MTs while the latter act as sites for attaching the chromosomes to the MTs. As noted by McIntosh the emphasis of most mitotic investigations is structural “because the spindle is a kind of machine, and numerous structural questions are obvious as one tries to understand a device which converts chemical energy into mechanical work.”During the course of our mitosis studies it was frequently necessary to reconstruct the three-dimensional (3D) ultrastructure of spindles from serial sections. To do this we utilized the STERECON system developed at the Albany HVEM facility. Briefly, prints of serial sections are enlarged to an optimum final magnification. For each section, profiles are drawn on clear plastic sheets outlining the chromosomes, mitochondria, and spindle MTs.
The spindle stage: A powerful optical tool
Authors: Gunter Mickey E. , Bloss F. Donald 
Published: June 2020

A single, reasonably homogeneous, nonopaque 30-to-300 μm crystal, mounted on a spindle stage and studied by immersion methods under a polarizing microscope, yields optical data frequently sufficient to identify and characterize a substance unequivocally. The data obtainable include (1) the orientation of the crystal's principal vibration axes and (2) its principal refractive indices, to within 0.0002 if desired, for light vibrating along these principal vibration axes. Spindle stages tend to be simple and relatively inexpensive, some costing less than $50. They permit rotation of the crystal about a single axis which is parallel to the microscope stage. This spindle or S-axis is thus perpendicular to the M-axis, namely the microscope stage's axis of rotation.A spindle stage excels when studying anisotropic crystals. It orients uniaxial crystals within minutes and biaxial crystals almost as quickly so that their principal refractive indices - ɛ and ω (uniaxial); α, β and γ (biaxial) - can be determined without significant error from crystal misorientation.
Scanning laser imagers with large working distances
Authors: Webb Robert H. 
Published: June 2020

The confocal Scanning Laser Ophthalmoscope exemplifies the new and exciting images available with scanning techniques, and particularly with a confocal arrangement. An ophthalmoscope might be considered a microscope whose objective is the cornea and lens of the eye. As such, it has a working distance of about 23 mm , a spherical object surface, and a resolution of 10 μm . With an external lens, the instrument can be configured as a general microscope of long working distance. We have made this change to facilitate viewing the convex surface of the eye's conjunctiva, benefitting from the great depth of focus available in a scanning system, and for observing melanotic skin lesions with the extreme rejection of scattered light available in a confocal arrangement.Scanning microscopes illuminate only one resolution element of the object at a time. Thus they encode the image information temporally - as a sequence of voltage pulses from an electro-optical detector.
Differential polarization microscopy: Theory and applications
Authors: Finzi Laura , Beach David , Bustamante Carlos , Garab Gyozo 
Published: June 2020

In Differential Polarization Microscopy two images of an object obtained usina orthogonal incident polarizations are subtracted from each other. The resulting difference image can display both magnitude and sign whose values will vary according to location in the image and the value of the local optical anisotropy of the object.Thus, Linear Dichroism and Circular Dichroism images of an object can be obtained.a) In-situ studies of the polymerization of Hb S in red blood sickle cells.-Mutant hemoglobin Hb S, present in sickle cell anemia, tends to aggregate at low pressures of oxygen forming polymers. Furthermore various polymers can align side by side. Using differential polarization image we can detect the angle of alignment and amount of polymerized HbS inside a red blood cell. We have also developed a supra-vital method for following the reversible process of polymerization and alignment inside a red blood cell, as a function of the oxygen pressure.
Arrangement of Acetylcholine Receptor Subunits in Different Physiological States
Authors: Toyoshima Chikashi , Unwin Nigel 
Published: June 2020

The nicotinic acetylcholine receptor (AChR) is a ligand-gated membrane ion channel consisting of 5 subunits (α, δ, γ, α and β). It exists in at least three different physiological states, namely, resting, desensitized and open states. Our goal is to elucidate the mechanism of ion gating by visualizing the three-dimensional structures of the receptor in different physiological conditions. We have been extending the previous electron image analysis on AChR embedded in ice to obtain the 3D density maps in the native (resting) and desensitized states at better than 20 Å resolution.There are two possible ways to analyse tubular crystals of AChR from Torpedo marmorata postsynaptic membranes. One is to treat them as superimposed 2D crystals by selecting wide flattened tubes embedded in very thin ice (Fig. 1a); the other is to utilize native helical symmetry preserved well in narrow tubes embedded in thick ice over holes (Fig. 1b). Analysing the same objects in two different ways will allow us to obtain reliable data on possibly small structural changes.
The Return of SEM Beam-Tilt Stereo
Authors: Pawley J. B. 
Published: June 2020

Stereo images add much to an accurate interpretation of surface images produced by the scanning electron microscope (SEM). Although the secondary electron (SE) signal contains considerable information about the micro-topography of the specimen, various non-topographic information may also be present. Because the process of binocular stereopsis by which we "see" in stereo depends chiefly on pattern recognition rather than on brightness, it discriminates against brightness artifacts and conveys a more accurate and if necessary, fully quantitative, impression of the actual micro-topography of the specimen surface.Stereo-pairs are normally produced by photographing a first view, tilting the specimen about 8 deg and then translating it so that the prominent features are again found in about the same position of the screen and finally recording the second image. The two images are viewed using one of a variety of devices designed to present each image only to the appropriate eye so that the two images can be fused and processed by the brain to produce a 3-D image.
Striated Muscle in the Intestine of Shrimp
Authors: Liu K. C. , Tsay S. F. , Yu Y. L. 
Published: June 2020

The shrimp, Penaeus monodon, commonly known as grass shrimp by local people. It has been cultured in large quantity and became one of the important aqua- cultural species in recent years. The morphology and histology of penaeid shrimps has been studied by many researchers (1). In our pathological study of the structural aspects of the digestive system, striated muscle was found in the area equivalent to the muscularis mucosa of tunica mucosa and tun.ica muscularis of vertebrates where smooth muscle is the basic structural element. This information is new to us , and to the best of our knowledge, there is no similar report among other Crustacea (2). This report is to present some of our evidence.Shrimps, Penaeus monodon, 50 g. in average body weight, were bought live from the market. Their intestines were disssected out and processed for both light electron microscopic studies. For electron microscopic observation a JEOL 100 CX electron microscope was used at 60 KV. attention was primarily concentrated on the circular muscle of the muscularis mucosa region.