bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scanning Electron Microscopy of Elliptocytes in Man and Llama
Authors: Pardo Matias , Grauer Robert C. , Swart James H. , Hartsock Robert J. 
Published: June 2020

Elliptical red cells may be found in man, camels, llamas, birds and reptiles. In man, these cells can occur as an autosomal dominant disease. Using a shadow-casting technic, Rebuck and Van Slyck found a constant bipolar massing of hemoglobin in the elliptical cells of man. This polar massing of hemoglobin was not observed in the red cells of the llama. From these observations they deduced that the elliptical cells in man were biconcave whereas the cells from the llama were uniformly elliptical without a zone of central thinning.The scanning electron microscope was used to confirm these observations by comparing the red cells from a patient with hereditary elliptocytosis with red cells from a llama. As shown in Fig. 1, the elliptical cells of man are canoe-shaped. Bipolar massing of hemoglobin in these cells is seen in the red cell in Fig. 3. These observations are contrasted with red cells from the llama which are also elliptical, but they lack a central zone of thinning as shown in Fig. 2.
Relationship of the Discocyte—Echinocyte Shape Transformation to Red Cell Surface Charge
Authors: Marikovskyand Y. , Brown C.S. , Wortis H.H. 
Published: June 2020

ATP-depletion of red blood cells (RBCs) by glucose deprivation transforms RBCs from the normal discocyte configuration into echinocytes. In the course of this shape change, there is a significant loss of membrane sialic acid, a decrease in cell surface negativity, and survival studies show that RBCs have an abbreviated life span. It is not known if the loss of negativity and decreased survival are directly related to nucleotide depletion or if they may be an inevitable consequence of the discocyte-echinocyte shape transformation.In the current study, we examined the effects of rapid discocyte-echinocyte transformations on RBC surface charge, as measured by cationized ferritin binding and agglutination rates in the presence of poly-L-lysine. Lysolecithin (LYL) is a strongly echinocytogenic lipid that transforms human RBCs into echinocytes in > 5 minutes, in contrast to ATP depletion by the method of Weed et al, which requires many hours to accomplish the same transformation.
Expression of HeLa Cell Surface Alkaline Phosphatase During Attachment to Gla
Authors: Max Fiskin A. , Melnykovych G. , Peterson G. 
Published: June 2020

We have reported a technique for accurately visualizing the surface distribution of alkaline phosphatase activity in replicas of cells cultured on glass [1] and have attempted to relate changes in observed activity to exposure to glucocorticoids which reduce (line S3K) or induce (S3G) total HeLa cell culture activity. Asynchrony and the history of each cell attachment to the glass substrate appeared as sources of variability in those studies. Here we relate the sequence of morphological changes followed by HeLa cells attaching to glass to changes in surface alkaline phosphatase activity, and demonstrate conspicuous differences between the response of the two lines to glucocorticoid.Clonal cultures grown (± dexamethasone) on coverslips were fixed briefly in buffered 2% gluteraldehyde, exposed to a Gomori type reaction mixture, rinsed and dried (critical point or air). Carbon-shadowed carbon replicas of the surface of the cultures were recovered by digestion, conserving the lead-product precipitate in situ. Surface morphology was visualized at .5μ underfocus, and the distribution of lead phosphate was recorded in near focus electronmicrographs.
Scanning Secondary Electron Microscopy of Myofibrils Using Transmission Techniques
Authors: Lamvik M. K. 
Published: June 2020

When observing small objects such as cellular organelles by scanning electron microscopy, it is often valuable to use the techniques of transmission electron microscopy. The common practice of mounting and coating for SEM may not always be necessary. These possibilities are illustrated using vertebrate skeletal muscle myofibrils.Micrographs for this study were made using a Hitachi HFS-2 scanning electron microscope, with photographic recording usually done at 60 seconds per frame. The instrument was operated at 25 kV, with a specimen chamber vacuum usually better than 10-7 torr. Myofibrils were obtained from rabbit back muscle using the method of Zak et al. To show the component filaments of this contractile organelle, the myofibrils were partially disrupted by agitation in a relaxing medium. A brief centrifugation was done to clear the solution of most of the undisrupted myofibrils before a drop was placed on the grid. Standard 3 mm transmission electron microscope grids covered with thin carbon films were used in this study.
Electron Probe Analysis and Ultrastructure of Cultured, Freeze Dried Vascular Smooth Muscle
Authors: Garfield R. E. , Somlyo A. P. 
Published: June 2020

Electron probe x-ray microanalysis at a spatial resolution of 1000 Å or better is now feasible and has been used to demonstrate mitochondrial deposits of divalent cations in ultrathin sections of fixed tissues. Monovalent and unbound ions, however, are lost and/or translocated during chemical fixation, necessitating the use of unfixed ultrathin frozen dried sections for electron probe analysis. The use of whole, frozen-dried cultured cells for electron probe analysis is easier than cryo-ultramicrotomy and presents some advantages such as rapid freezing rates attainable and imaging at conventional (75-80 kV) voltages. Smooth muscle cells from guinea pig aortas were cultured on Formvar-coated nylon grids (Fig 1). Grids with attached cells were blotted on filter paper and plunged into liquid nitrogen and dried frozen in a vacuum evaporator.In dried whole cells examined at 75 or 80 kV, the cell outline and processes were distinct and the nuclei and mitochondria containing electron opaque granules identifiable (Fig 2,3).
Silica Incorporation in the Cell Wall of the Singing Cell of Urtica dioica
Authors: Sowers A. E. , Thurston E. L. 
Published: June 2020

Plant stinging emergences exhibit functional similarities in that they all elicit a pain response upon contact. A stinging emergence consists of an elongated stinging cell and a multicellular pedestal (Fig. 1). A recent ultrastructural investigation of these structures has revealed the ontogeny and morphology of the stinging cells differs in representative genera in the four plant families which possess such structures. A unique feature of the stinging cell of Urtica dioica is the presence of a siliceous cell wall in the apical portion of the cell. This rigid region of the cell wall is responsible for producing the needle-like apparatus which penetrates the skin. The stinging cell differentiates the apical bulbous tip early in development and the cell continues growth by intercalary addition of non-silicified wall material until maturity.The uppermost region of the stinging cell wall is entirely composed of silica (Fig. 2, 3) and upon etching with a 3% solution of HF (5 seconds), the silica is partially removed revealing the wall consisting of individualized silica bodies (Fig. 4, 5).
Electron Microscopy of Bacteriophage T7 Internal Head Proteins
Authors: Serwer P. 
Published: June 2020

The genome of bacteriophage T7 is a duplex DNA molecule packaged in a space whose volume has been measured to be 2.2 x the volume of the B form of T7 DNA. To help determine the mechanism for packaging this DNA, the configuration of proteins inside the phage head has been investigated by electron microscopy. A core which is roughly cylindrical in outline has been observed inside the head of phage T7 using three different specimen preparation techniques.When T7 phage are treated with glutaraldehyde, DNA is ejected from the head often revealing an internal core (dark arrows in Fig. 1). When both the core and tail are present in a particle, the core appears to be coaxial with the tail. Core-tail complexes sometimes dislodge from their normal location and appear attached to the outside of a phage head (light arrow in Fig. 1).
Ultrastructure of a Strigeoid Cercaria (Alaria) (Trematoda, Diplostomatidae)
Authors: Dernaree Richard S. , Wootton Donald M. 
Published: June 2020

As a continuation of our previous studies of cercarial ultrastructure: furcocercous, longifurcate-pharyngeate cercariae identified as Alaria sp. were harvested from infected snails (Heliosoma sp.) collected near Chico, CA.Cercariae were fixed in 2.5% Sorensen's phosphate-buffered glutaraldehyde, and then 1% osmium tetroxide in the same buffer, dehydrated in ethanol, and flat-embedded in Spurr's resin.Both the body (Fig. 1) and the tail had pronounced filamentous surface coats. Spines were numerous on syncytial body tegument (Fig. 1) and tail furcae, but absent on the tail stem.The circular and longitudinal muscles of the body (Fig. 1), circular and radial muscles of the ventral sucker, and excretory bladder muscles (Fig. 2) all had a "non-striated" appearance which is characteristic of slowly contracting fibers. The latter finding contrasts with the "striated" nature of oral sucker muscles in Cryptocotyle lingua. Tail muscles were striated like those of Cotylurus (another closely related furcocercous, strigeoid cercaria).
Quick-Freezing With High Time Resolution Of Fast Physiological Events
Authors: Sommer Joachim R. 
Published: June 2020

Quick-freezing methodology has made three major contributions to our ability to relate structure to function: 1. Quick-freezing, especially when followed by freeze-fracture, is suited to study the ultrastructure of unfixed biological material as close to the native state as can possibly be obtained. 2. Physiological events associated with morphological changes at the level of electron microscopic resolution can be stopped at any desired time interval and, thus, analysed against a known time scale and, 3. Microchemical measurements, e.g. of elemental concentrations and their spatial displacements, can be obtained by electron dispersive X-ray microanalysis from freeze-dried frozen sections of quick-frozen biological material. Indeed, it is now possible to investigate, simultaneously, anatomical, physiological and microchemical parameters in a single cell, with a precise time scale thrown in for good measure.In the following I shall describe the techniques that we employ to study the morphology of single intact skeletal muscle fibers of the frog at known time intervals following electrical stimulation. The methodology is the judicious extension, including some modifications, of procedures whose efficacy is mostly uncontroversial and a matter of scientific record.
Electron Beam Damage in High-Temperature Polymers
Authors: Kumar Satish , Krause Stephen J. , Adams W. W. 
Published: June 2020

Electron microscopy studies of polymers are limited due to beam damage. Two concerns are (i) the damage mechanism in a particular material, and (ii) the maximum dose for a material before damage effects are observed. To understand these aspects of beam damage of polymers several systematic studies have been under taken. From the knowledge of the dose required for damage to the polymer crystals, optimum parameters for electron microscopy imaging can be determined.Electron beam damage can be quantified by changes in (i) mass, (ii) diffraction contrast, (iii) diffraction intensity, and (iv) electron energy loss spectrum (EELS) intensity. Dose required to damage a material depends on which of the above criteria is applied. Therefore to compare the beam damage results for different polymers it is necessary to use the same criteria. We have studied beam damage by measuring the loss of diffraction intensity. Diffraction intensity decreases exponentially with increasing electron dose, after a short initial period. The intensity, I(D), of a particular reflection at a dose, D, can be given by the following equation.
Forensic Examination of Bulb Filaments By the Sem
Authors: Thorsen Knud Aage 
Published: June 2020

In the investigation of traffic accidents, whether auto collisions or airplane crashes, it is often very important to establish whether the headlights as well as the signal and warning system of the vehicles were on or off at the moment of the accident. Legal responsibility for the specific case may thus be assigned, and countermeasures can be taken to reduce the risk of recurrences.Fortunately the incandescent lamps themselves, or more specific, their filaments, often give the key to clearing the case. The stresses generated on a filament by the accelerations and sudden stop of a collision, produce deformation and fracture phenomena, with characteristic differences between hot and cold filaments resulting. Further evidence may arise if the glass bulb is broken at the accident, as the tungsten metal of the filament will be oxidized if hot. Glass splinters from the broken bulb hitting a hot wire will melt in the same way.
Aberration-Correcting Properties of the Hyperbolic Electron Mirror
Authors: Rempfer F. F. , Mauck M. S. 
Published: June 2020

Spherical and chromatic aberration are inherent in electron lenses. Under certain conditions the possibility exists that these lens aberrations can be eliminated or compensated. The conditions under which such corrections are possible (in principle) have been characterized originally by Scherzer and later by Septier. One type of correcting system involves the use of an electrostatic electron mirror. The work presented here deals with the properties of hyperbolic electron mirrors and the conditions for matching the correcting properties of a mirror to the spherical and chromatic aberration of a lens or lens system.In an earlier work by the authors, the properties of the hyperbolic mirror were studied for rays incident on the mirror parallel to the optical axis. In the present work, symmetrical rays are studied.
Energy-Dispersive Spectroscopy in A 400Kv Electron Microscope
Authors: S. Suzuki  , Y. Bando  , H. Kitajima  , T. Honda  , Y. Harada  , M. Kersker  
Published: June 2020

A Si(Li) detector for X-ray energy dispersive spectroscopy (EDS) has been installed on a 400 kV EM, the JEM-4000EX, which is also interfaced with a scanning device (ASID40) and electron energy loss spectrometer (ASEA40). The EM's basic performance, i.e., resolving power, is 0.23 nm at 400 kV. X-ray microanalysis in a high-voltage EM has many advantages, but few reports have been published because of some severe instrumental problems originating from it's high energy electron beam. To overcome these problems many modifications have been made on the EM column.The modifications are divided into two aspects. One is the reduction of bremsstrahlung and the other is the protection of the Si(Li) detector from hard X-ray radiation from the upper parts of the detector, especially condenser lens (CL) aperture. To reduce bremsstrahlung many parts of the wall which electron beam might hit are covered with graphite and the materials for CL fixed apertures are changed to light elements. To protect the detector X-ray shielding parts made of heavy metals (W, Ta, Pb) and with a total thickness of more than 30 mm are set between the CL aperture and the Si(Li) detector.
Current Status of Solid-State X-Ray Systems
Authors: Peckerar Martin , Tousimis Anastasios 
Published: June 2020

Solid state x-ray sensing systems have been used for many years in conjunction with scanning and transmission electron microscopes. Such systems conveniently provide users with elemental area maps and quantitative chemical analyses of samples. Improvements on these tools are currently sought in the following areas: sensitivity at longer and shorter x-ray wavelengths and minimization of noise-broadening of spectral lines. In this paper, we review basic limitations and recent advances in each of these areas. Throughout the review, we emphasize the systems nature of the problem. That is. limitations exist not only in the sensor elements but also in the preamplifier/amplifier chain and in the interfaces between these components.Solid state x-ray sensors usually function by way of incident photons creating electron-hole pairs in semiconductor material. This radiation-produced mobile charge is swept into external circuitry by electric fields in the semiconductor bulk.
The Microstructure of Melt-Spun Iron Neodymium Permanent Magnet Materials
Authors: Dickenson R. C. 
Published: June 2020

Rapidly-quenched iron rare-earth boron alloys, with appropriate heat treatment, exhibit commercially promising permanent magnetic properties. This paper will report the results of an AEM characterization undertaken to explain the origin of the magnetic properties of an iron-neodymium-boron alloy in terms of its microstructure. Ribbons of Fe76 Nd16 B8 were prepared by melt-spinning, and were subsequently annealed at 700°C for 6 minutes to promote growth of a fine-grained structure. Samples were prepared for AEM by ion-milling the ribbons on a cold stage and examined using a Philips 400T TEM/STEM equipped with an energy dispersive x-ray unit.Three different microstructures are commonly observed in these alloys, and several others have been found in isolated cases.
Bacterial Trace Fossils in Eocene Kaolin
Authors: Barker W. W. 
Published: June 2020

Spheroidal electron-dense masses averaging two microns in diameter comprise up to 20% of a thin Eocene grey kaolin in the upper part of the Huber Fm. near Wrens, Georgia. TEM and SEM reveal that the microspheroids consist of tangentially oriented kaolinite platelets enclosing much finer, delicate intergrowths of secondary authigenic minerals.Many types of bacteria and algae produce mucopolysaccharidal exudates which can attach clay platelets. Clay-clad microorganisms are especially common in marine and estuarine environments, where high ionic strength compresses the electric double layer of kaolinite sufficiently for van der Waals forces to aid its attachment to exudates. Maclean and Smart found clay-clad prokaryotic cells in recent estuarine sediments. Avnimelech, et al. demonstrated mutual flocculation of algae and clay upon addition of electrolyte. Because the size and structure of the clay-clad microspheroids in the Eocene kaolin closely resembles the clay-clad bacteria in recent marine muds, they are interpreted as trace fossils of bacteria.
Surfaces and Surface Rearrangements at Atomic Resolution
Authors: Smith David J. , Bursill L.A. , Marks L.D. , Lin Peng Ju 
Published: June 2020

With proper operating conditions and suitable specimens, it is possible with the latest HREMs to obtain atomic-level information from surface profile images. In this paper, we describe recent observations of metal and oxide surfaces, including atomic rearrangements, using the JEOL 4000EX at Arizona State University. This microscope, which is equipped with a top-entry, double-tilt, ultra-high-resolution specimen stage, bettered the guaranteed resolution figure of 1.8A during installation. It is therefore an ideal instrument for investigating surface morphology at atomic resolution.Gold surfacesOur original objective was to further our previous observations of atomic rearrangements on extended Au surfaces by imaging in the novel (100) projection. Although this requires a resolution of better than 2.0A, it is possible to observe, as shown in Fig. 1, details of the surface morphology including surface steps, facetting and the presence of adatoms. Moreover, when cleaned of carbon, it is found that substantial atomic motion occurs along the surface and videotape recordings are now being analysed to establish whether there is any correlated motion of atomic columns.
Reaction Products of Cathodically Protected Steel in Soil
Authors: Moore T. J. 
Published: June 2020

Cathodic protection is employed in soils to reduce the corrosion sustained by metallic structures in aggressive soil environments. This study is designed to investigate the mechanisms of cathodic protection :n soils by observing the solid phase products which precipitate as a result of these reactions.Cathodic protection of mild steel specimens was monitored using sacrificial magnesium anodes placed in two soils at four depths. After a period of one year, the samples were retrieved, vacuum dried, and subjected to scanning electron microscopy, electron microprobe analysis, and x-ray diffraction.The solid phases precipitated at the soil/metal interface may be categorized into two groups: 1) A thin coating of iron oxides and 2) A thicker layer of magnesium salts.
Application of Cross-Sectional Transmission Electron Microscopy to the Characterization of Ion-Implanted Semiconductors
Authors: Sands T. 
Published: June 2020

Direct implantation of dopant ions is the most precise method for obtaining a desired dopant profile in a semiconductor substrate. However, in order to achieve satisfactory electrical properties, lattice defects introduced by the energetic dopant ions and by the subsequent annealing process must be confined or eliminated. Because of the many parameters which can be varied during implantation and annealing, it is not generally feasible to survey all conditions. Consequently, the most efficient approach is to understand the mechanisms of defect formation and annealing so that guidelines for choosing a set of implantation/annealing conditions can be determined.Since implantation depths are usually much less than one micron, suitable defect characterization techniques must demonstrate high spatial resolution. Cross-sectional transmission electron microscopy (XTEM) is one such technique. With a resolution (lateral and depth) of ∼0.2nm, the atomic structure of implantation-related defects is accessible.
Electron Channeling Analysis and Z-C0ntrast Imaging of Dopants in Semiconductors
Authors: Pennycook S. J. 
Published: June 2020

The determination of dopant distribution and lattice location are key elements in the characterization of ion-implanted, thermally processed semiconductors. We present here two analytical techniques for this purpose. The first is a channeling technique for the determination of substitutional fractions of dopants or impurities in any crystal structure, and the second is a means for imaging and elemental mapping of heavy elements in light materials, even if they are in solution.Atom Location by Electron Channeling AnalysisIt has only recently been realized that the orientation dependence of characteristic x-ray emission close to a Bragg reflection, long regarded as a hindrance to accurate microanalysis, can form the basis of a powerful lattice location technique. The first studies of this kind located trace elements in layer structure minerals, where it was known that the only possible sites for the impurity lay within the layer planes A and/or B. These restraints exclude many materials and here a generalization to any crystal structure is described.
Direct Observation of Defect Motion in Silicon By High-Resolution Transmission Electron Microscopy
Authors: Parker M. A. , Sinclair R. 
Published: June 2020

Observations of defect motion by high resolution transmission electron microscopy (HRTEM) are rare. Unfortunately, the application of this technique has been limited to a few unique materials, those that can obtain sufficient thermal energy for the initiation of atomic motion through the heating effects of the incident electron beam. In earlier work, it was speculated that events such as the motion of crystal defects, observed in cadmium telluride (CdTe) with the electron beam heating method, might become evident in materials such as silicon (Si) if only sufficiently high temperatures could be achieved (∼ 600°C) in-situ.A silicon specimen with a suitable population of defects was chosen for examination; it consisted of a cross-section of.3 μ ﹛100﹜ silicon on ﹛1102﹜ sapphire (SOS from Union Carbide) which was implant amorphized by 28Si+ ion implantation at an energy of ∼ 170keV.