bluuebunny/crossref_metadata_2025 huggingface dataset:
Doppler shift of electron waves
Authors: Möllenstedt G. , Lichte H.
Published: June 2020

In an electron mirror interference microscope (1) two coherent partial waves are reflected by an electrostatic mirror (Fig.1). The mirror surface (“object”) is slowly tilted using a cylindrical piezo-ceramic spacer (€ = Δl/Δ U = 6 Å/V) one cm in length and one cm in diameter which produces a tilt angle of Δl/s = ɛ-Δu/s where s is the length of the lever arm (Fig.2). The piezo-voltage U is increased linearly with time so that two points at a lateral distance Δx on the mirror surface move with velocities perpendicular to the mirror which differ from each other by Δv = ɛ(dU/dt)Δx/s. The two partial waves reflected at the mirror at a lateral distance Δx from each other suffer a Doppler frequency shift ΔrD= ΔE/h. ΔE = (4/3)mvΔv = (4/3)hΔv/λ is the difference of the energies taken up by the electrons of the two partial beams when they are reflected from the moving mirror, taking into account that the reflection consists of a continuous deceleration and reacceleration in the homogeneous field in front of the mirror surface (2).
Imaging of tilted, extended, thin phase-objects
Authors: Schiske P.
Published: June 2020

In images of extended strongly tilted specimens, different parts of the object are subject to different defocus. This makes it possible to obtain, by a single exposure, an overall view of the transfer properties of the objective [1,2]; on the other hand, in reconstruction work it requires the use of correcting procedures [3]. The importance of both points seems to justify formal investigation--restricted here to thin phase objects. The geometrical data are shown in Fig. 1; the axis of tilt is normal to the plane of the drawing and is used as coordinate axis X2. Representing the scattered amplitude by u(k1,k2) where spatial frequencies k by δ = λk represent the inclination δ of the different components of the wave field a(x1,x2,z), one has

Putting z = x1 one finds for the amplitude immediately beyond the object

(1)
Signal-to-noise enhancement in bright field images by incoherent superposition
Authors: Kunath W.
Published: June 2020

Bright field imaging of heavy single atoms with hollow cone illumination results in images with only slightly reduced central contrast, compared to axial illumination, but strongly suppressed subsidiary maxima. This holds for certain values for the cone angle and defocus and is due to the triangle-shaped contrast transfer function. Computer-simulated micrographs of Hg atoms on a carbon support film show that the inherent structural noise is suppressed as well, resulting in twice as good a signal-to-noise ratio compared to axial illumination. The phase grating approximation is used.

The computer-generated carbon film with an area of 48 Å by 48 Å is a random network of atoms, the sampling distance corresponding to 0.75 Å. It is fitted to give a noise-to-background ratio N = 5% in the Scherzer focus with the data λ = 3.7 • 10-2 A; Cs = 0.5 mm; Cc = 0.8 mm of our microscope.
Image contrast of cluster atoms taking account of inelastic scattering
Authors: Kanaya Koichi , Oikawa Tetsuo , Mizukoshi Nobuaki , Ikeguchi Kou , Shino Masayuki , Hojou Kiichi
Published: June 2020

Based on the image formation theory, the image contrast of cluster atoms taking account of inelastic scattering are simulated with the experimental result for carbon film made by sputter deposition. The contrast g for the cluster atoms has been calculated by integrating the scattering wave for coherent waves, and for incoherent waves the amplitude scattered outside the limiting angle αset by the aperture respectively,

in which the first term (real part of the wave function we (υj,γj))is the phase contrast due to the total phase which is combined by ηj(O) and γj. The second term and the third term show the amplitude contrast by the elastic and inelastic scattering absorption respectively. The wave function of inelastic scattering Wine(υj,γj) is given by
Structure and migration of planar defects in crystals observed in atomic scale
Authors: Hashimoto H. , Sugimoto Y. , Takai Y. , Endoh H.
Published: June 2020

As was demonstrated by the present authors that atomic structure of simple crystal can be photographed by the conventional 100 kV electron microscope adjusted at “aberration free focus (AFF)” condition. In order to operate the microscope at AFF condition effectively, highly stabilized electron beams with small energy spread and small beam divergence are necessary. In the present observation, a 120 kV electron microscope with LaB6 electron gun was used. The most of the images were taken with the direct electron optical magnification of 1.3 million times and then magnified photographically.

1. Twist boundary of ZnS

Fig. 1 is the image of wurtzite single crystal with twist boundary grown on the surface of zinc crystal by the reaction of sulphur vapour of 1540 Torr at 500°C. Crystal surface is parallel to (00.1) plane and electron beam is incident along the axis normal to the crystal surface. In the twist boundary there is a dislocation net work between two perfect crystals with a certain rotation angle.
Some aspects of the defect structure in an austenitic stainless steel
Authors: Gonzalez R. , Bru L.
Published: June 2020

The analysis of stacking fault tetrahedra (SFT) in fatigued metals (1,2) is somewhat complicated, due partly to their relatively low density, but principally to the presence of a very high density of dislocations which hides them. In order to overcome this second difficulty, we have used in this work an austenitic stainless steel that deforms in a planar mode and, as expected, examination of the substructure revealed planar arrays of dislocation dipoles rather than the cellular structures which appear both in single and polycrystals of cyclically deformed copper and silver. This more uniform distribution of dislocations allows a better identification of the SFT.

The samples were fatigue deformed at the constant total strain amplitude Δε = 0.025 for 5 cycles at three temperatures: 85, 293 and 773 K. One of the samples was tensile strained with a total deformation of 3.5%.
Image contrast of dislocation in anisotropic cubic crystals
Authors: Ohr S.M.
Published: June 2020

The calculations of the image contrast of dislocation loops reported in the past have made use of the displacement fields which are derived under the assumptions of elastic isotropy. The only exception is the work of Yoffe, but it is based on the asymptotic field of an infinitesimal loop applied to the first order analytical theory of image contrast. It is therefore desirable to calculate the image contrast by exact numerical integration of the equations of the dynamical theory of electron diffraction making use of the displacement field of a finite loop derived from the anisotropic elasticity theory. Recently, we have presented a scheme by which the displacement field of a circular loop of finite size can be calculated for anisotropic cubic crystals from the Fourier transform of the elastic Green's function. In the present study, this numerical scheme has been combined with the image simulation technique developed earlier to calculate the image contrast of dislocation loops in anisotropic cubic crystals.
Interstitial defect clusters in non-stoichiometric NiAl
Authors: Mukerjee D. , Loretto M.H. , Smallman R.E.
Published: June 2020

Introduction

As part of an extensive study of the nature of defect structure in B2 alloys the nature of defects in NiAl is being studied in some detail. In earlier work Ball reported and interpreted observations of unusual lattice defects in Al-rich NiAl. He showed that these defects lay on {100} and considered several possible models to account for the intrinsic displacement contrast observed. The absence of such defects on the Ni-rich side of stoichiometry was taken as confirmation of his chosen model. In the present paper it is shown that similar defects do in fact occur in Ni-rich specimens and that the nature of the displacement fringe contrast is extrinsic on both sides of stoichiometry. Possible formation mechanisms and structures of these defects are discussed.

Experimental

Specimens with compositions covering the whole composition range both sides of stoichiometry were prepared by argon arc melting appropriate weighed amounts of Ni and Al, and discs for examination by electron microscopy prepared from these as-cast specimens and from specimens homogenized at 1300°C for 72 hrs.
Application of many-beam theory of diffraction contrast for examination of nature of faults in Co3Pd ordered films
Authors: Vershinina L.I. , Kopilov G.A. , Osipova R.E. , Pynko V.G.
Published: June 2020

Single crystal Co3Pd films were prepared by usual method of vacuum evaporation of alloy co0.75Pd0.25 on the (001)-plane of MgO single crystal heated up to 260°C at pressure of 10-4 torr. The films were annealed at 650°C for two hours with following cooling to the room temperature with speed of 0.5 dg/min at pressure of 10-5 torr. The alloy films of about 600 Å thick were examined. The structure of the CO3Pd films was investigated with transmission electron microscopy, operating at 100 kV. The deviation of the origin of the Ewald sphere from the symmetrical position was determined from the position of the Kikuchi lines. Films were oriented so that only reflections along the 010 systematic row were strongly excited. The film surface was parallel to the (00l)-plane (Fig.1a). The Co3Pd films had an ordered L12 lattice. Observed light-field images contains a large amount of the fringes, oriented along the [110] and [100] (Fig.lb).
Progress in transmission electron microscopy of NaCl crystals
Authors: Strecker H. , Strunk H.
Published: June 2020

Scope

Upon exposure to ionizing radiation, NaCl, like all other alkali halides, is damaged severely, mainly by formation of defects due to electronic excitations. Investigation by transmission electron microscopy is hence only possible, if special experimental measures are taken in order to reduce this type of damage effectively. This has been achieved by cooling the specimens to <20K in the microscope /1/ or by using a high accelerating voltage of ≥400kV /2/. The simultaneous application of both precautions /3/ provides observation times long enough to permit a detailed contrast analysis and has been demonstrated successfully in the investigation of pure NaCl crystals.

It is the aim of the present paper to survey the recent progress of this experimental technique. Some details will be reported on the dislocation distribution observed in (001)-orientated NaCl crystals, which were deformed in compression at 220K and 78K. The preparation of the samples involved sectioning, subsequent pinning of the dislocations by X-irradiation, waterfreee thinning and transfer into the microscope /4/.
Electron microscope observations of iron-catalyzed gasification of graphite
Authors: Szirmae A. , Rao V.U.S. , Fisher R.M.
Published: June 2020

A well known catalytic effect of transition metals and particularly iron in contack with carbonaceous carbon exposed to oxidizing or hydrogenating atmospheres (02, CO-CO2, H2-H2O) has been investigated by scanning and high voltage transmission electron microscopy in a program aimed at determining the fundamental mechanisms of the gasification reactions. Samples of polycrystalline planchets and single crystal flakes of graphite were reacted at temperatures from 650°to 1100°C in “wet” and “dry” hydrogen . Quantitative electron microscope observations were supplemented by weight loss measurements and continuous gas chromatograph analysis of the CO and CH4, produced. Prior to exposure to the reacting gases, small particles of metallic iron are formed on the surface of single crystal graphite flakes or pressed carbon planchets by vacuum deposition of thin films ranging from 1 Å to 2000 Å in thickness.
In-situ application of dc electric field on ferroelectric substances in an electron microscope
Authors: Yamamoto N. , Yagi K. , Honjo G.
Published: June 2020

A technique of in-situ application of a dc electric field on a specimen in an electron microscope has been developed to directly observe dynamic phenomena due to the electric field. In the present technique a thickness of a specimen is so thin that a very high electric field can be applied; a few volt of the potential difference across the specimen of the order of 1000 Å thick gives a field as high as 105 V/cm. An additional field application electrode was incorporated not only in a specimen heating holder but also in a liquid helium cooling stage which had been constructed in our 1aboratory. Thus, the experiments could be performed in a wide temperature range of 13-1000K. Fig.la schematically depicts a specimen holder installed in the cooling stage. The detailed arrangement around a specimen is shown in Fig.1b. An electric potential is applied between electrodes of thin A1 films vacuum deposited on the both faces of the specimen.
A standard for transmission electron spectroscopy
Authors: Maher Dennis , Joy David , Mochel Peggy
Published: June 2020

A variety of standard specimens is needed in order to systematically investigate the instrumentation, specimen, data reduction and quantitation variables in electron energy-loss spectroscopy (EELS). Pure single element specimens (e.g. various forms of carbon) have received considerable attention to date but certain elements of interest cannot be prepared directly as thin films. Since studies of the first and second row elements in two- or multicomponent systems will be of considerable importance in microanalysis using EELS, there is a need for convenient standards containing these species. For many investigations a standard should contain the desired element, or elements, homogeneously dispersed through a suitable matrix and at an accurately known concentration. These conditions may be met by the technique of implantation.

Silicon was chosen as the host lattice since its principal ionization energies, EL23 = 98 eV and Ek = 1843 eV, are well removed from the K-edges of most elements of major interest such as boron (Ek = 188 eV), carbon (Ek = 283 eV), nitrogen (Ek = 400 eV) and oxygen (Ek = 532 eV).
Electron back-scattering patterns in a field emission gun scanning electron microscope
Authors: Harland C.J. , Klein J.H. , Akhter P. , Venables J.A.
Published: June 2020

INTRODUCTION.The electron back-scattering pattern (EBSP) is a simple means of obtaining the crystallographic orientation of samples in the SEM. Kikuchi bands are observed on a fluorescent screen ∼15mm in front of a (tilted) sample /l/ and shadows, for example of three spherical balls, can be used to obtain orientation determinations accurate to ± 0. 5° /2/. We have also shown that a fibre-optic detector of angular diameter <2θB can be used to form images of polycrystalline material with markedly increased grain contrast /3/.

In the present paper we report that these techniques have been transferred onto an ultra-high vacuum SEM equipped with a field emission gun (FEG). The higher brightness of the FEG enables the spot size to be reduced markedly. The transition between the orientation of one grain and the next has been shown to be as sharp as 50nm. Shifts due to sub-grain boundaries down to ∼1° can be readily seen
Cell structure properties during in situ creep experiments in the H.V.E.M.
Authors: Caillard D. , Martin J.L.
Published: June 2020

The behaviour of the dislocation substructure during the steady stage regime of creep, as well as its contribution to the creep rate, are poorly known. In particular, the stability of the subboundaries has been questioned recently, on the basis of experimental observations |1||2| and theoretical estimates |1||3|. In situ deformation experiments in the high voltage electron microscope are well adapted to the direct observation of this behaviour. We report here recent results on dislocation and subboundary properties during stationary creep of an aluminium polycristal at 200°C.

During a macroscopic creep test at 200°C, a cell substructure is developed with an average cell size of a few microns. Microsamples are cut out of these specimens |4| with the same tensile axis, and then further deformed in the microscope at the same temperature and stain rate. At 1 MeV, one or a few cells can be observed in the foil thickness |5|. Low electron fluxes and an image intensifier were used to reduce radiation damage effects.
Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2
Authors: Long N.J. , Loretto M.H. , Lloyd C.H.
Published: June 2020

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).

This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.
Formative time and structure of martensite from amorphous FeNi films
Authors: Bostanjoglo O. , Liedtke R.
Published: June 2020

Using a fast detector the applicability of CTEM was extended to follow phase transformations in the nanoseconds range. Iron-rich FeNi films vapour-quenched at 4 K grow in an amorphous state with peculiar crystallographic and magnetic properties (1). On exceeding a critical thickness or on heating amorphous films with inferior thickness up to a critical temperature, the films martensiticly crystallized. This diffusionless transformation occurred in such films where the amorphous phase was stabilized by stress and not by reacting gases.

The present paper reports investigations on both the structure of martensite and on the propagation of martensitic crystallization of amorphous 70 at % FeNi films. They were grown at 4 K on carbon foils in the EM as previously described (1). The propagation of the phase transformation was investigated by following the change of the bright-field image intensity with fast scintillator, photomultiplier and oscilloscope. Crystallization processes occurring in areas of 1.5 μm ∅ and within 10 ns were resolved in first experiments (fig. 3).
Lowicryl resins
Authors: Armbruster B. L. , Kobayashi G. S. , Medoff G. , Heuser J. E. , Carlemalm E. , Hobot J. A. , Acetarin J. D. , Villiger W. , Kellenberger E.
Published: June 2020

In the recent past the use of low temperature methods for specimen preparation have become more widespread as the limitations of conventional fixation and embedding procedures have become evident. Since conventional fixatives such as glutaraldehyde do not cause instantaneous cessation of cytoplasmic movement, there can result considerable post-fixation redistribution of cytoplasm and membrane distortions, forming such artifactual structures as lomasomes in fungi and mesosomes in bacteria. This in turn translates into a loss of fidelity between the ultrastructural image and the organization we can observe in a living cell. The deleterious effects of conventional fixation have been well documented in the literature of fungal ultrastructure and have fostered the use of freeze-substitution procedures. The advantage of employing freeze-substitution techniques to study the ultrastructure of bacteria is illustrated in Figure 1. E. coli were rapidly frozen and substituted at -80°C. These results correspond to the images seen in frozen hydrated sections (1). DNA is believed to lie in the ribosome-free region outlined in Fig. 1b.
Scalp pilar tumor with intranuclear fibrils
Authors: Lim B. S.
Published: June 2020

Pilar tumor is considered by some to be a low grade squamous carcinoma. Although there are instances of metastasis to regional nodes, the tumor is extremely slow growing and recurrence are rare. Electron microscopic examination of this tumor revealed new morphological finding of intranuclear fibrils.

Description of the tumor: A large, nodular, fungating and focally ulcerated tumor was noted in the center of the scalp of a mental patient. This mass measured 8.0x4.0x3.0 cm. On cut surface the tumor was well circumscribed and appeared to extend deep into the subcutaneous tissue. On inspection this lesion was gray-white and granular and in some areas there were foci of calcification, hemorrhage and necrosis.
Scanning electron microscopy in diagnostic pathology
Authors: Siew S.
Published: June 2020

Scanning electron microscopy (SEM) is a newcomer into the field of microscopy but it has made tremendous strides in the two decades since its inception. In its evolution, it has progressed from an esoteric instrument to its application as a diagnostic tool. SEM has certain attributes which make it a desirable, if not essential, complement to the other, more established, modes of microscopy - light - (LM) and transmission electron microscopy (TEM). By means of its ability to collect secondary electrons generated from the surface of a specimen exposed to the electron beam, SEM registers a stereoscopic rendering of the field examined. This basic principle is comparable to that of direct vision, where the image is formed by the generation of secondary photons from an object exposed to a beam of light. Hence, the highly descriptive term “microvision” has been applied to SEM. SEM has the capacity to collect backscattered electrons (BEI).
Ultrastructure of mesotheliomas
Authors: Dardick Irving
Published: June 2020

With the extensive industrial use of asbestos in this century and the long latent period (20-50 years) between exposure and tumor presentation, the incidence of malignant mesothelioma is now increasing. Thus, surgical pathologists are more frequently faced with the dilemma of differentiating mesothelioma from metastatic adenocarcinoma and spindle-cell sarcoma involving serosal surfaces. Electron microscopy is amodality useful in clarifying this problem.

In utilizing ultrastructural features in the diagnosis of mesothelioma, it is essential to appreciate that the classification of this tumor reflects a variety of morphologic forms of differing biologic behavior (Table 1). Furthermore, with the variable histology and degree of differentiation in mesotheliomas it might be expected that the ultrastructure of such tumors also reflects a range of cytological features. Such is the case.
On the assembly and structural modulation of lens fiber junctions
Authors: Benedetti E.L. , Dunia I. , Lien Do Ngoc , Vallon O. , Louvard D. , Bloemendal H.
Published: June 2020

In the eye lens emerging molecular and structural patterns apparently cohabit with the remnants of the past. The lens in a rather puzzling fashion sums up its own natural history and even transient steps of the differentiation are memorized. A prototype of this situation is well outlined by the study of the lenticular intercellular junctions. These membrane domains exhibit structural, biochemical and perhaps functional polymorphism reflecting throughout life the multiple steps of the differentiation of the epithelium into fibers and of the ageing process of the lenticular cells.

The most striking biochemical difference between the membrane derived from the epithelium and from the fibers respectively, concerns the presence of the 26,000 molecular weight polypeptide (MP26) in the latter membranes.
Distribution of the main intrinsic polypeptide in lens fiber membrane domains
Authors: FitzGerald Paul G. , Horwitz Joseph , Bok Dean
Published: June 2020

The lens fiber cell of the vertebrate eye is a postmitotic, highly differentiated cell which is derived from the lens epithelium. Upon differentiation into lens fibers, the epithelium expresses a unique membrane protein (Main Intrinsic Polypeptide, MIP) with a molecular weight in excess of 26,000. These lens fiber cells are extraordinarily rich in intercellular junctions which can occupy up to 64% of the cell surface. Lens fiber junctions, frequently referred to as “gap junctions”, co-purify with MIP and it has therefore been suggested from biochemical evidence that MIP is a junctional protein.

Electron microscopic immunoferritin studies in which rabbit anti-bovine MIP antiserum was incubated with isolated bovine lens fiber membranes have shown that MIP is present in abundance in pentalaminar profiles conventionally regarded as lens junctions (Figure 1).
On the structural organization of biological pumps and channels
Authors: Zampighi G. , Kreman M.
Published: June 2020

The plasma membranes of most animal cells contain transport proteins which function to provide passageways for the transported species across essentially impermeable lipid bilayers. The channel is a passive transport system which allows the movement of ions and low molecular weight molecules along their concentration gradients. The pump is an active transport system and can translocate cations against their natural concentration gradients. The actions and interplay of these two kinds of transport proteins control crucial cell functions such as active transport, excitability and cell communication. In this paper, we will describe and compare several features of the molecular organization of pumps and channels. As an example of an active transport system, we will discuss the structure of the sodium and potassium ion-activated triphosphatase [(Na+ +K+)-ATPase] and as an example of a passive transport system, the communicating channel of gap junctions and lens junctions.
Freeze-etch toruses of circular and linear DNA topological states exhibit characteristic circumference measurements
Authors: Ruben George C. , Marx Kenneth A.
Published: June 2020

We have used freeze-etch low Pt-C metal level (9Å) TEM to visualize torus shaped structures formed from 1 mM spermidine collapse of identical length (5386 bp) but different topological state linear and nicked, circular ϕX-174 RF II DNAs. We have shown that toruses condensed from any DNA are organized by a circumferential DNA winding and these structures are thought to have a DNA organization similar to that in certain double stranded DNA bacteriophage and viruses. One of the most accessible parameters of a torus population is the circumference distribution since toruses are invariably oriented nearly horizontal to the ice in the freeze-etch experiment at the time of replica formation. Therefore, both inner and outer measured circumference distributions of toruses formed from 5386 bp nicked, circular and linear ϕX-174 RF II DNA are presented in Figures 1 and 2 respectively. Within each group of toruses there is a highly significant correlation (0.94) between individual torus inner and outer circumference values.
Scanning electron microscopy of feline gastric mucosa
Authors: Al-Tikriti M. , Al-Bagdadi F. , Hoskins J. , Titkemeyer C. , Strain G.
Published: June 2020

The advent of techniques for scanning electron microscopy stimulated the study of the surface of the gastric mucosa because of better visualization of the surface morphology. Scanning electron microscopy has been used recently in studies of the surface morphology of the gastric mucosa of the rat, the ferret and man, and the guineapig. Information is not available on the gastric mucosa of the cat. However, large numbers of cats are brought to veterinary clinics for stomach disorders. Knowledge of the normal morphology of the gastric mucosa is necessary for more accurate morphological diagnosis of gastric disorders. Four preconditioned cats were used in this investigation. Each cat was euthanatized by I/V injection of 3 ml of T-62 solution. The stomach was removed, opened along the greater curvature and rinsed repeatedly with saline. The stomach was pinned on a paraffin tray with the mucosa up. It was fixed in 5% glutaraldehyde in phosphate buffered pH 7.4 (0.15 M) at room temperature.
Backscattered-electron imaging of the colloidal gold surface marker
Authors: de Harven E. , Leung R. , Christensen H.
Published: June 2020

A variety of markers have been used for surface labeling with the scanning electron microscope (1). They are all recognized in the secondary electron imaging (SEI) mode on the basis of their characteristic sizes and shapes. This makes it difficult, however, to recognize unambiguously markers of small size (smaller than 40 nm). Unfortunately, markers of such size are needed if one wishes to minimize steric hindrance phenomena (2) and therefore obtain high efficiency labeling. We have found that the atomic number contrast of the colloidal gold marker, expressed in the backscattered electron imaging (BEI) mode, alleviates this difficulty to a significant extent (3).

Human peripheral blood leukocytes, separated by sedimentation in presence of Dextran, were attached to poly-1-lysine pretreated carbon coated grids. The cells were then fixed for 5 min with 0.25% solution of buffered glutaraldehyde, pH 7.2, extensively rinsed with 0.1% glycine in PBS, and incubated for 30 min, at room temperature with an IgM monoclonal antibody (D2) specifically recognizing, a surface antigen of mature granulocytes.
Feulgen-thiocarbohydrazide-silver methenamine(FTS) reaction: An improved silver methodology for light and electron microscopy of DNA
Authors: Hanker J. S. , Giammara B. L.
Published: June 2020

A number of cytochemical methods have been Introduced to reveal nuclear components at the ultrastructural level. Many of these, however, are topographic, i.e., identify structures rather than molecular species (1). Indeed, even the search for modifications of the Feulgen reaction to render the nuclear sites of chromatin or DNA electron opaque have not met with a great deal of success (1). Thus the aldehyde or pseudoaldehyde groups on apurinic acids, generated by the action of IN HCl at 60° on DNA, could not be shown by condensation with thiocarbohydrazide (TCH) or thiosemicarbazide and subsequent osmication (2,3). Feulgen reactions with silver end products resulting from the reaction of silver compounds with apurinic-acids have been used since 1924, but these reactions either lack specificity or cannot be used for high resolution studies. Although an abstract appeared in 1972 on a Feulgen reaction employing TCH and silver proteinate (4), neither light micrographs nor a full paper have appeared.
Mercury in primate Paneth cells following methylmercury hydroxide ingestion
Authors: Crooker A. R. , Johnson D. E. , Mottet N. K.
Published: June 2020

The toxicity of mercury and its compounds is widely recognized. Symptoms of mercury intoxication vary greatly depending on mode of entry, form of mercury, dose, and duration of exposure. In humans, the principal toxic effects of inorganic mercury involve the liver and kidney. Organic mercurials such as methylmercury have a more pronounced effect on the central nervous system.

Pharmacological studies suggest an intestinal elimination of organic mercurials and the possibility of an intestinal lesion associated with mercury. Autoradiographic studies have indicated that uptake of 203HgCl2 by rat paneth cells exceeded that of other cells of the small intestine. Paneth cells line the bottoms of intestinal crypts. They are pyramidal in shape with basally located nuclei and large secretory granules in their apical aspect which contain the bacteriolytic enzyme lysozyme.
The SR of skeletal muscle: Its structure after quick-freezing and freeze-etching, following field stimulation of single intact muscle fibers
Authors: Sommer J.R. , Nassar R. , Wallace N.R.
Published: June 2020

It is known that the P faces of freeze-fractured SR of fixed and cryoprotected striated muscle fibers are studded with particles, whereas the E faces remain smooth, except for two staggered rows of pits in the junctional SR (JSR) which face transverse tubules (junctional pits). Freeze-fracture after quick-freezing of native skeletal muscle provides similar images (1). We have used freeze-etching to look at the SR's structure in single intact skeletal muscle fibers (r.temporaria) without stimulation, following varied post-stimulation intervals, and in tetanus. Single intact skeletal muscle fibers were isolated and quick-frozen as previously reported (2). After quick-freezing, the fibers were transferred to a Balzers 301 device and etched for 3 minutes at -100°C, followed by unidirectional Pt evaporation with an electron gun and carbon coating.
Polymorphism in neurofilament protein assemblies induced by magnesium (II), calcium (II), and tannate ions
Authors: Clapin D.F. , Metuzals J.
Published: June 2020

The squid giant axon has become well established as a model preparation for studies of the organization of the neurofilamentous network. A comprehensive model of this neurofilament structure as a three-dimensional supramolecular complex of fibrous proteins has been developed. The network pervades the axon and appears to have a functionally specific, intrinsic polymorphism taking the form of dense and less-dense, local, quasi-crystalline domains. The loss of this dynamic capacity for phase transition has been hypothesized as the underlying process through which abnormal configurations of neurofilaments arise, an example of which may be the paired helical filaments of Alzheimer's disease. An investigation was undertaken of neurofilament protein ultrastructure in a variety of experimentally produced ionic environments with the aim of defining in a systematic way general charge and concentration effects on assembly patterns.
Subcellular localization of actin in chlorella
Authors: Michaels A. , Kriho V. , Solomonson L.
Published: June 2020

Although most often thought of as a contractile protein, actin has been localized and isolated from many non-muscle eukaryotic cells. The function of actin has also been described in certain algal cells. However, little is known regarding the subcellular distribution of actin and its relationship to function in algal cells.

Using the immunocytochemical techniques of Wolosewick and co-workers, we have determined the subcellular location of actin in the unicellular green algae, Chlorella vulgaris.

Pellets of Chlorella were fixed in 0.25% glutaraldehyde (EMS) in growth media for 1 hr on ice. The cells were washed (2X) with 10mM potassium phosphate buffer, pH 7.5. These cells were maintained on ice in phosphate buffer until dehydration and embedding in polyethylene glycol (PEG) (MW3350). PEG is a water miscible wax which can be removed easily from the section.
The structure and basic operating modes of a STEM
Authors: Vander Sande John B.
Published: June 2020

The scanning transmission electron microscope (STEM) represents a major advance in the microanalytical capabilities of instruments available to materials scientists. The STEM concept resulted from the desire to combine features of the transmission electron microscope (TEM), scanning electron microscope (SEM), and the electron microprobe. Several types of STEMs are currently in use; they can be divided into roughly three categories based on origin and philosophy of design. First are the “dedicated” STEMs, pioneered by Crewe and his coworkers, which generally use a field-emission electron gun housed in an ultra-high-vacuum system. A conventional TEM may also be equipped with a scanning attachment and an electron detector and/or spectrometer, yielding what may be referred to as a TEM(S). Finally, in practice an SEM may be fitted with a transmission stage; in this case the designation SEM(T) may be most appropriate. The first two designs are by far the most popular for currently available commercial instruments.
Very High Resolution: A Place for the Stem
Authors: Crewe A. V.
Published: June 2020

It is often advantageous to take a step backwards from the problems of the moment and ask ourselves where we are going and in particular to ask whether or not we are going in the right direction. Preparing an article such as this one is sufficient incentive for such reflection but it also reminds me of the enquiries that I made when first entering the field of electron microscopy almost twenty years ago. At that time I asked several of my friends and acquaintances in biology what they would really like to see in the way of future developments for microscopy. Almost universally the answer was “more resolution”, although the more knowledgeable ones said “better lenses” and one even specified “an f:l lens”.
Finding the Right Problems: Some HREM Applications to Interfaces
Authors: Cherns D.
Published: June 2020

The use of high resolution electron microscopy (HREM) to determine the atomic structure of grain boundaries and interfaces is a topic of great current interest. Grain boundary structure has been considered for many years as central to an understanding of the mechanical and transport properties of materials. Some more recent attention has focussed on the atomic structures of metalsemiconductor interfaces which are believed to control electrical properties of contacts. The atomic structures of interfaces in semiconductor or metal multilayers is an area of growing interest for understanding the unusual electrical or mechanical properties which these new materials possess. However, although the point-to-point resolutions of currently available HREMs, ∼2-3Å, appear sufficient to solve many of these problems, few atomic models of grain boundaries and interfaces have been derived. Moreover, with a new generation of 300-400kV instruments promising resolutions in the 1.6-2.0 Å range, and resolutions better than 1.5Å expected from specialist instruments, it is an appropriate time to consider the usefulness of HREM for interface studies.
Fine structure of crack in ceramics
Authors: Kakibayashi Hiroshi , Nagata Fumio
Published: June 2020

Many kinds of ceramics have been developed providing enough insulation, heat conduction or shock resistance. For the characteristics of strong toughness of the ceramics, movements of cracks by applying a force are noteworthy, because most ceramics are hardly distorted.

In the present works, behavior of cracks in ceramics is observed with high resolution electron microscopy. Silicon nitride (Si3N4) ceramics were made by sintering in nitrogen atmosphere at 1800°C. Some Y2O3 and AlN were added to assist the sintering. A piece of the ceramics was sliced and polished mechanically untill 20μm in thickness. The specimen was mounted on a single hole grid, and was thinned with an ion etching equipment to be thin enough to observe.
Resolution in the low-voltage SEM
Authors: Joy David C
Published: June 2020

The resolution of a secondary electron image is determined by the spatial distribution of the secondaries leaving the surface. This distribution results from two components, SE1 which are the secondaries generated by the incident beam and which carry the high resolution information, and SE2 which are the secondaries produced by exiting electrons and which carry information mimicing that in the backscattered signal. The integrated intensities of these two components are comparable, but their spatial characteristies are quite different. In order to study the factors which limit resolution it is therefore necessary to model the events which give rise to the two groups of secondaries.
Observation of secondary slip systems in tungsten bicrystals
Authors: Fekete J. R. , Gibala R.
Published: June 2020

The deformation behavior of metallic materials is modified by the presence of grain boundaries. When polycrystalline materials are deformed, additional stresses over and above those externally imposed on the material are induced. These stresses result from the constraint of the grain boundaries on the deformation of incompatible grains. This incompatibility can be elastic or plastic in nature. One of the mechanisms by which these stresses can be relieved is the activation of secondary slip systems. Secondary slip systems have been shown to relieve elastic and plastic compatibility stresses. The deformation of tungsten bicrystals is interesting, due to the elastic isotropy of the material, which implies that the entire compatibility stress field will exist due to plastic incompatibility. The work described here shows TEM observations of the activation of secondary slip in tungsten bicrystals with a [110] twist boundary oriented with the plane normal parallel to the stress axis.
Growth of near noble metal Pd and Pt thin film silicides morphology and structure
Authors: Alessandrini E. I. , Aboelfotoh M. O.
Published: June 2020

Considerable interest has been generated in solid state reactions between thin films of near noble metals and silicon. These metals deposited on Si form numerous stable chemical compounds at low temperatures and have found applications as Schottky barrier contacts to silicon in VLSI devices. Since the very first phase that nucleates in contact with Si determines the barrier properties, the purpose of our study was to investigate the silicide formation of the near noble metals, Pd and Pt, at very thin thickness of the metal films on amorphous silicon.

Films of Pd and Pt in the thickness range of 0.5nm to 20nm were made by room temperature evaporation on 40nm thick amorphous Si films, which were first deposited on 30nm thick amorphous Si3N4 membranes in a window configuration. The deposition rate was 0.1 to 0.5nm/sec and the pressure during deposition was 3 x 10 -7 Torr. The samples were annealed at temperatures in the range from 200° to 650°C in a furnace with helium purified by hot (950°C) Ti particles. Transmission electron microscopy and diffraction techniques were used to evaluate changes in structure and morphology of the phases formed as a function of metal thickness and annealing temperature.
Surface zone-axis patterns
Authors: Eades J. A. , Shannon M. D. , Meichle M. E.
Published: June 2020

In electron diffraction from crystals, whether it be in reflection or transmission, the intensity of the emergent beams varies in a complex way with the angle that the incident beam makes with the crystal structure. The techniques for displaying this variation of intensity as a function of incident beam orientation have mostly been applied to zone-axis orientations, where the variation is particularly elaborate. The resulting patterns, known as zone-axis patterns or zaps, have become an important part of transmission electron microscopy.

There are several techniques for obtaining zaps. The best known is convergent-beam diffraction but they can also be obtained in the form of bend-contour patterns and Tanaka patterns, and by rocking methods.
Lattice misfit by convergent-beam electron diffraction - Part I: Geometry measurement
Authors: Lin L. S. , Walsh J. M.
Published: June 2020

The conventional method of lattice misfit determination in superalloys has involved the use of x-ray diffraction employing a parafocal camera. While the inherent accuracy and reliability of measurements made by such a technique is widely known, the value of any lattice parameters obtained represent an average for the volume characterized by the x-ray beam. Furthermore, the effects of enforced coherency between the γ and γ' phases in nickel-base superalloys often result in considerable peak broadening, so that the fundamental γ and γ̍ reflections are not resolved. Convergent beam electron diffraction (CBED) provides high spatial resolution for lattice misfit measurement (100 nm or smaller spot size) and overcomes some of the problems with the conventional method of measurement. The procedures used in the current CBED work are based on a geometrical analysis first described by Steeds. When a (111) zone axis beam direction is used a characteristic triangle formed by various ﹛359﹜ holz lines appears in the zero order central disc as shown in Figure 1 when operating at 100 kV.
Laser recording of mass memory data
Authors: Bartolini Robert A.
Published: June 2020

Optical recording systems capable of information storage and retrieval using a highly focused laser beam as the recording and playback source have been developed to a point where product introduction has begun. The products range from low-data-rate (10-20 Mbits/sec), single disc (1010 to 1011 bits), random access electronic office filing cabinets (augmenting existing word processing units) to high-data-rate (100's of Mbits/sec), multidisc (1013 bits on line “jukeboxes”), random access archival mass memories.

The advantages that optical disc recording systems provide are:

Very high information density (1010 to 1011 bits per disc have been demonstrated);

Very high data rates (up to 50 Mbits/sec in a single channel recorder have been demonstrated);

Rapid random access to the data (<<1 sec) has also been demonstrated;

The cost of the media has been projected to be 5x10-8 cent/bit;

The media have the potential for archival storage (10 years or more) of the data.
Microanalysis in the EM 902: Tests on a new TEM for ESI and EELS
Authors: Egle W. , Rilk A. , Bihr J. , Menzel M.
Published: June 2020

One important goal in biological and medical research as well as in material sciences is the microanalysis of specimens, i. e. the determination of the spatial distribution and concentration of relevant atomic elements, such as Ca, P, S, N, O, Al, Fe, Ti or Mg ideally over every point in the image in relation to the underlying matrix. Microanalysis has generally been carried out in a probe forming or scanning system by spot analysis using EDX or EELS. Elemental mapping is however more efficacious in a spectrometer that filters entire images in parallel. For energy loss electrons several such systems have been built experimentally (1-7), but inspite of results which have indicated a sensitivity of detection as good as 2 x 10-21 g and a spatial resolution in analysis of about 0.5 nm, applications in biology and material sciences (2,7 - 9) no commercial EM with an integrated imaging spectrometer is available today.
Thickness and composition determinations from T.E.M. specimens using both x-ray and backscattered electron data
Authors: Ball M.D. , Lagace H. , Thornton M.C.
Published: June 2020

The backscattered electron coefficient η for transmission electron microscope specimens depends on both the atomic number Z and the thickness t. Hence for specimens of known atomic number, the thickness can be determined from backscattered electron coefficient measurements. This work describes a simple and convenient method of estimating the thickness and the corrected composition of areas of uncertain atomic number by combining x-ray microanalysis and backscattered electron intensity measurements.

The method is best described in terms of the flow chart shown In Figure 1. Having selected a feature of interest, x-ray microanalysis data is recorded and used to estimate the composition. At this stage thickness corrections for absorption and fluorescence are not performed.
Secondary fluorescence effects on x-ray microanalysis
Authors: Angelini P. , Bentley J.
Published: June 2020

The structure and composition of intergranular phases present in TiB2 hotpressed or sintered with Ni additive are being analyzed to evaluate sintering mechanisms. Analytical electron microscopy (AEM) has shown that the major intergranular phase present in TiB2 hot-pressed with Ni is Ni3B, but in TiB2 sintered with Ni is a boride tau phase. Energy dispersive x-ray spectroscopy (EDS) of the intergranular Ni3B indicated a Ti content of ∼8 at. % (all compositions quoted are normalized where at. % Ti + at. % Ni = 100%). However, phase diagram data show Ni3B to be a line compound with limited Ti solubility. The present experiments were performed to assess the suspected influence of secondary fluorescence effects on EDS analyses.