bluuebunny/crossref_metadata_2025 huggingface dataset:
An in Vitro Study of Necrosis in the Crayfish Giant Axon
Authors: Sides Paul J.
Published: June 2020

Several electron microscopic studies have shown that in some types of cells allowed to undergo necrosis on exposure to various injurious agents, there are discrete and predictable alterations in ultrastructure. In crayfish nerve cords exposed to in vitro anoxic conditions, necrosis also proceeds in an orderly manner. These changes are characterized by alterations in Schwann cell morphology occurring shortly before discernable changes in the axon proper.

Ventral nerve cords of the crayfish (Procambarus clarkii) were dissected, divided into control and experimental portions after tieing the ends with thread, and mounted in covered plastic Petri dishes which contained 50 ml.
Pulmonary Acariasis: A Scanning Electron Microscope Study of Lung Mites in the Rhesus Monkey
Authors: Brummer M. E. , Darby R. E. , Wong M. M.
Published: June 2020

Infestation by the mite Pneumonyssus simicola causes pulmonary acariasis in several simian primate species, particularly the rhesus monkey, Macaca mulatta. These lung mites, common in Old World monkeys captured in the wild, are infrequently encountered in monkeys born and raised in captivity. The mite infestation is usually asymptomatic and clinically not detectable. Since the lesions caused by the mites may complicate experiments in pulmonary research and make interpretations of results difficult, studies were made to characterize the lung mites and lesions to minimize this problem.

Lungs from four Macaca mulatta were fixed by perfusion via the airways at 30 cm of water pressure with cacodylate-buffered formaldehyde-glutaraldehyde.
Inelastic Scattering and Beam Damage of Biological Molecules
Authors: Isaacson M.
Published: June 2020

There are two kinds of interactions which an incident electron can experience in traversing a thin specimen. It can be elastically scattered from the atomic nuclei without losing energy. Or it can be inelastically scattered from the atomic electrons and impart energy to the specimen. Elastic interactions are useful for high resolution imaging and produce negligible damage. Inelastic interactions, however, can result in molecular or chemical damage. This is important in biological electron microscopy, since experiments have shown that for 30 KeV electrons in carbon one gets 1.6 inelastic events for every elastic event. Moreover, this ratio increases slightly with voltage.

The energy loss spectrum of electrons which have traversed thin specimens is directly related to the probability of exciting a particular electronic level.
Ultrastructure of Intranuclear Round Bodies of Enta-Moeba Histolytica After Dnasa and Rnasa Treatment
Authors: Gonzàlez Angulo A. , Ruiz de Chàvez I. , Treviño N.
Published: June 2020

Recent morphological studies of E. histolytica have revealed the presence of several intranuclear structures which are clearly distinguished from other nuclear components. These are round membrane bound bodies of variable marked electron density averaging from 15 to 40 milimicra in diameter (Fig. 1). Their intranuclear location and persistance within the nucleus along the various stages of the life cycle of E. histolytica seems to indicate that these structures may have a functional role in the nucleus. The present study was undertaken to determine the existence of DNA and RNA in this intranuclear structures.

Trophozoites of E. histolytica ABRM strains obtained from monoxenic cultures were fixed for 35 minutes in 2.5% Glutaraldehyde, 0.1M sodium cacodilate buffer.
Eye Pigment Granule Ultrastructure in Drosophila Melanogaster
Authors: Sun Donald C. , Crang Richard E.
Published: June 2020

The compound eyes of wild type Drosophila melanogaster normally contain two pigments—ommochrome (brown) and drosopterine (red). However, sepiapterine (yellow), which is a biochemical precursor of drosopterine, is present in several mutant flies instead of drosopterine—or in addition to it. Transmission electron microscope observations reported here reveal fine structural differences between the pigment granules at various times post-pupation in D. melanogaster wild type as well as the mutants sepia and clot.

Eyes from pupae at 54, 72 and 90 hours post-pupation were fixed with glutaraldehyde and osmium tetroxide followed by dehydration and embedment in Epon 812. Alternate thin (50-70 nm) and thick (1-2 μ) sections from the embedded material were sectioned with an ultramicrotome for electron and light microscopy respectively.
Genesis of Giant Mitochondria in Alcoholic Cardiomyopathy
Authors: Sekhri K.K. , Alexander C.S. , Nagasawa H.T.
Published: June 2020

Despite the fact that approximately 100 million persons in the USA drink alcohol and, of these, about 15 million are alcoholics, very little is known of ethanol toxicity to the heart. In order to elucidate the ultrastructural effects of alcohol in experimental animals, 20 male Simonsen rats were maintained on a well-balanced Purina rat chow diet but provided with 15% alcohol ad libitum in place of drinking water up to a period of 55 weeks. The other group of 20 rats received rat chow and tap water and served as controls. This method permits mimicking human cases where well-nourished business and professional men resort to heavy intake of alcohol along with regular food over a long period of time.
The Effects of Puromycin on the Ultrastructure of the Golgi Complex
Authors: Sturgess J. M. , Moscarello M. A.
Published: June 2020

The most extensively studied site of action of puromycin is the ribosome where puromycin detaches nascent peptide chains, inhibiting protein synthesis. Ultrastructural and biochemical studies have shown the puromycin causes disaggregation of polyribosomes, accompanied by disorganisation of rough endoplasmic reticulum. Vacuolisation and regression of the Golgi complex have been reported in the Golgi complex after puromycin treatment in various cell types including liver, pancreas, thyroid and intestinal cells. Previous studies have not described details either of the sequence of changes in the Golgi complex or the reversal of changes after puromycin.

In this study, the effects of puromycin have been evaluated in Golgi membranes isolated from rat liver by differential centrifugation. Isolated membranes have been examined in the electron microscope by negative staining with phosphotungstic acid and in ultrathin sections.
The Fine Structure of Rat Granulosa Cell Cultures Correlated with Progestin Secretion
Authors: Crisp T. M. , Denys F.R.
Published: June 2020

The purpose of this paper is to present observations on the fine structure of rat granulosa cell cultures grown in the presence of an adenohypophyseal explant and to correlate the morphology of these cells with progestin secretion. Twenty-six day old immature female rats were given a single injection of 5 IU pregnant mares serum gonadotropin (PMS) in order to obtain ovaries with large vesicular follicles. At 66 hrs. post-PMS administration (estrus indicated by vaginal smear cytology), the ovaries were removed and placed in a petri dish containing medium 199 and 100 U penicillin/streptomycin (P/S)/ml. Under a 20X magnification dissecting microscope, some 5-8 vesicular follicles/ovary were punctured and the granulosa cells were expressed into the surrounding medium. The cells were transferred to centrifuge tubes and spun down at 1000 rpm for 5 mins.
Evidence of Hormone Induction of Milk Proteins in Normal and Malignant Mammary Gland Cultures
Authors: McCarty Kenneth S. , Jones Richard F. , Nixon Jon C. , McCarty Kenneth S.
Published: June 2020

Normal epithelial cells from mammary glands of mature virgin mice synthesize increasing levels of casein and α-lactalbumin when cultured in the presence of insulin, hydrocortisone, and prolactin. in the absence of DNA synthesis or when DNA synthesis is blocked, the augmentation of milk protein production does not occur. It would appear that a necessary coupling of secretory protein production to DNA synthesis or mitosis or both is essential.

Mammary tissue from 10-12 day pregnant nulliparous C3H mice, BA type mammary adenocarcinoma, and H2712 type mammary adenocarcinoma have been compared in their response to insulin, dexamethasone and prolactin in organ and tissue cultures.
Electron Microscopy of Bacterial-Like Microorganisms From the Antarctic Soil
Authors: Uydess Ian , Vishniac Wolf
Published: June 2020

Recently, a number of soil samples isolated from geographically distinct regions in the Asgard Range-Vanda Lake area of the Antarctic, were shown to contain living microorganisms which displayed bacterial-like morphologies. The microorganisms isolated from these samples were observed to have heterogeneous structural characteristics ranging from those with “typical” Gram - or Gram + morphologies, to those with “unique” morphologies which may be intermediate to the eubacteria and lower algae.

Cell pellets prepared from the various soil samples were rinsed in phosphate buffered saline and fixed in Dalton's Chrome Osmium. These were then post-fixed in aqueous Uranyl Acetate, dehydrated in a graded alcohol series, and then embedded in Epon for electron microscopy. Examination of these preparations revealed the existence of several distinct morphologic types of bacterial-like microorganisms.
A Report Of Morphologically Aberrant Virus Particles in Cells Infected With MSV (FelLV) Virus
Authors: Al-Adhami R. A. , Chapman A. L.
Published: June 2020

Fujinaga et al reported MSV induced rat and hamster osteosarcoma which showed an occassional unusual bud in the rat induced tumors. Savage and Hackett and Hackett and Sylvester reported abnormal type C virus in UCLB cells derived from Balb/3t3 cells infected and transformed with MLV. They wer unable to demonstrate sarcoma virus activity. Fischinger and O‘Connor reported the infection of cat embryo cells by a centrifugally induced aggregate of murine sarcoma virus and feline leukemia virus designated as MSV(FelLV). This virus gave rise to a defective, focus forming virus which propagated in cat cells but not in mouse cells.

In the present study the morphoiogy of the MSV(FelLV) virus obtained from Dr. Fischinger and maintained in our laboratory since 1970 will be reported. Feline embryo fibroblasts (established in our lab.) and Crandall feline kidney cells (Cutter-Haver-Lockhart, Shawnee, Kansas) were used in this study.
Studies of Circular DNA Using a New Electron Microscopic Technique
Authors: Gordon C. N.
Published: June 2020

Gordon and Kleinschmidt have described a new preparative technique for visualizing DNA by electron microscopy. This procedure, which is a modification of Hall's “mica substrate technique”, consists of the following steps: (a) K+ions on the cleavage surface of native mica are exchanged for Al3+ions by ion exchange. (b) The mica, with Al3+ in the exchange sites on the surface, is placed in a dilute aqueous salt solution of DNA for several minutes; during this period DNA becomes adsorbed on the surface. (c) The mica with adsorbed DNA is removed from the DNA solution, rinsed, dried and visualized for transmission electron microscopy by Hall's platinum pre-shadow replica technique.

In previous studies of circular DNA by this technique, most of the molecules seen were either broken to linears or extensively tangled; in general, it was not possible to obtain suitably large samples of open extended molecules for contour length measurements.
Studies of Aggregates of Two Muscle Proteins with Scanning Transmission and Conventional Transmission Electron Microscopy
Authors: Lamvik M. K. , Isaacson M. S. , Crewe A. V.
Published: June 2020

Studies of the structures of various aggregates of proteins from vertebrate striated muscle have begun, using in particular the scanning transmission electron microscope (STEM). The high collection efficiency of this microscope has been noted elsewhere and the contrast advantage and signal selection capabilities have been demonstrated.

Although the instrument can produce high contrast images of unstained and unfixed biological material, it is not clear which preparation methods might maintain the native structure of such material. So the study begins on familiar ground with conventionl negatively stained preparations, While later steps will include less conventional methods.

Rabbit tropomyosin Mg-tactoids in suspension were received from Dr. Carolyn Cohen (of Children's Cancer Research Foundation, Boston). The tactoids have a primary periodicity of 395 Å. Isolated myofibrils were obtained from Joseph Etlinger (of this University); myosin was extracted from them by a method similar to that of Dow and Stracher.
Tissue Structures in Frozen Sections
Authors: Tokuyasu K. T. , Singer S. J.
Published: June 2020

When tissue pieces or isolated cells are fixed with glutaraldehyde, infused with 0.6 to 1.6 M sucrose solutions, frozen in liquid N2 and ultra-thin sectioned at -50 to 90°C, they show an excellent sectioning consistency. The frozen sections can be picked up from the knife edge with a droplet of a near saturated sucrose solution, and removed to room temperature. The sections then melt and spread on the droplet, and are transferred to coated grids and are then stained.

Tissue preparations fixed only with glutaraldehyde are expected to be superior to conventional preparations, which involve OsO-fixation, dehydration with chemical solvent and embedding in plastic, in the preservation of lipid and protein conformations and, therefore, in the observation of tissue structures at the molecular level.
Spermiogenesis in the Nine-Banded Armadillo
Authors: Weaker Frank J.
Published: June 2020

The testes of mature armadillos were fixed by either perfusion or immersion. The morphology of the seminiferous tubules and the process of spermiogenesis were studied.

The developing spermatids are generally oval in shape and contain a centrally placed nucleus. A well-developed Golgi apparatus, scattered mitochondria, centrioles, smooth endoplasmic reticulum, and a chromatoid body are observed within the cytoplasm. Granules formed within the Golgi appear to coalesce to form the acrosomal granule, which is enclosed within a vesicle (Fi,g. 1). The acrosome adheres to the nucleus at the anterior pole of the developing spermatid. The acrosome vesicle collapses and extends over the anterior two-thirds of the nucleus (Fig. 2). As this vesicle expands, the Golgi continues to release granules into the vesicle. Concomitant with acrosome formation, the centrioles and chromatoid body migrate to the posterior pole of the developing cell.
Contribution of Ruthenium Chloride to the Ultracytochemical Study of Cerebellar Cortex
Authors: Castejón Orlando J. , Castejón Haydée V. , Viloría Maria E. , Rivero Indalecio
Published: June 2020

Ruthenium Red has been utilized for the histochemical demonstration of acid mucopolysaccharides (Luft, 1971 a,b). In the present study a related compound ruthenium chloride has been applied to the study of cerebellar cortex in an attempt to evaluate its staining properties and potential value as a histochemical reagent for the demonstra tion of acid glycosaminoglycans.

Albino mice were perfused with a mixture of glutaraldehyde-cacodylate sucrose buffer solution, pH 7.4 to which 0.1% ruthenium chloride was added. After perfusion the cerebellar cortex was sectioned in small blocks which were fixed by immersion in a fresh similar mixture and secondarily immersed in a 0.5% osmium tetroxide-cacody-late sucrose buffer with addition of 0.05% ruthenium chloride. Ultrathin sections were stained by uranyl acetate and lead citrate. Cerebellar cortex fixed only in glutaralde-hyde and stained with uranyl and lead salts were used as controls.
Ultrastructure of Mitotic Cells in Paraganglia of the Syrian Hamster
Authors: Mascorro Joe A. , Yates Robert D.
Published: June 2020

Extra-adrenal chromaffin tissue classified as paraganglia is said to exert its greatest influence during prenatal life while the adrenal medulla is still largely undifferentiated. Various reports indicate that the majority of paraganglionic tissue in the mouse, rat, guinea pig and human involutes rapidly following birth, at which time the adrenal medulla and sympathetic nervous system come into prominence. Ultrastructural observations of hamster abdominal paraganglia have shown that this tissue is precocious, and it is interesting to note that mitotic cells are observed in these organs of neuroectodermal origin.

Syrian hamsters 13 days of age or less were perfused with 3% glutaraldehyde buffered with 0.2M phosphate to pH 7.1-7.2.
Quantitative Immunocytochemistry of Corticotropin by the Unlabeled Antibody Enzyme Method with and without Peroxidase-Antiperoxidase Complex (PAP)
Authors: Petrali John P. , Moriarty Gwen C. , Sternberger Ludwig A.
Published: June 2020

The unlabeled antibody enzyme method localizes antigen by reaction with (1) specific antiserum (primary antibodies), (2) antiserum to the primary immunoglobulin, (3) antiperoxidase (anti-PO) and (4) peroxidase (P0). The reaction is developed with hydrogen peroxide as substrate for P0 and diaminobenzidine (DAB) as co-substrate, followed by osmication. Anti-PO can be used in the form of antiserum (procedure A), purified antibody (procedure B), or steps (3) and (4) can be combined by the use of purified, soluble PAP (procedure C). Only at relatively low resolutions does identification of antigen depend on specific staining. High resolution localization depends on identification of the characteristic ring-shaped PAP molecules (Fig. 1).

We have compared the sensitivities of procedures A, B and C upon staining serial Araldite sections of rat pituitary intermediate lobes using anti17-39 corticotropin as primary antiserum. PAP contained 3.33 mg anti-PO, 1.2 mg PO/ml and was essentially pure. It was employed at a standard dilution of 1:50. Antiserum and purified antibody to PO were used at standard dilutions containing equivalent amounts of anti-PO (1:24 for antiserum, 1:5 for purified antibody).
Enzyme Histochemistry of Lactic Dehydrogenase
Authors: Baba N.
Published: June 2020

Intracellular localization of lactic dehydrogenase (LDH) was studied both with a stain method with an osmiophilic tetrazolium salt and with a conjugated antienzyme antibody method. For the stain method an osmiophilic thiocarbamyl nitroblue tetrazolium (TCNBT) was applied on the paraformaldehyde-fixed rat heart muscle. TCNBT deposits were seen diffusely in the sarcoplasm and in the intermembranous space of mitochondria. Portions of the sarcoplasmic reticulum (SR) showed positive reactions. When urea, which inhibits LDH isoenzymes 3, 4 and 5 in the fixed rat heart muscle, was added the staining in SR was abolished. However the general staining pattern of the heart muscle cells remained unchanged.
Electron microscopy of rod/coil molecular composites
Authors: Krause S. J. , Adams W. W.
Published: June 2020

Molecular composites are a new class of structural polymers which are lightweight, high-strength, high-modulus, and environmentally resistant. A rigid-rod, extended chain, polymer is used to reinforce a matrix of flexible, coil-like polymer with the intent of achieving a composite on the molecular level which is analagous to a macroscopic chopped-fiber reinforced composite. The critical factor in making a molecular composite is that the rod-like reinforcing molecules be well dispersed and not phase separate from the matrix polymer to insure that the aspect ratio (ratio of length to width) of the reinforcing phase has a high value. This paper reports the first transmission electron microsopy (TEM) study of phase separation in molecular composites.
High-resolution microscopy of a GTB-type Rb-Nb-oxide
Authors: Olsen A. , McLean J.D. , Goodman P.
Published: June 2020

Synthesis of specific tunnel compounds has recently been stimulated by their potential application in both cation storage and ionic conductor technologies. However, the theoretical understanding of these compounds is insufficient to be predictive about the tunnel retentivity for various cations. At present HREM seems to be the most practical method of examining this experimentally when, as in the present case, several different types of tunnels are competing for the available cations.

A new type of structure in the Rb-Nb-O system, named GTB by Bhide and Gasperin, was first analysed by Gatehouse et al using single crystal x-ray diffraction. It was found to have the tetragonal framework structure indicated schematically in Figure 1, in which corner-linked NbO6 octahedra form 4, 5, 6 and 7-sided tunnels. A similar structure was later found by Bhide and Gasperin in the Tl-Nb-O system. The cell dimensions of the Rb-compound are: a = 27.49 Å; c = 3.96 Å. The composition of the framework is Nb54O146.
Tetragonal precipitation in the system Y2O3-ZrO2
Authors: Lanteri V. , Heuer A. H. , Mitchell T. E.
Published: June 2020

The major applications of partially stabilized zirconia (PSZ) concern materials in which the microstructures are in the two phase regions (cubic-tetragonal or cubic-monoclinic). The aim of this paper is to discuss the occurrence of tetragonal precipitation in yttria-PSZ. Despite the similarity with other doped zirconia alloys (Mg-PSZ, Ca-PSZ), the shape, the habit planes and mechanisms of precipitation are found to be different for Y-PSZ. Single crystals, obtained from skull melting, with composition 8w%-Y2O3 were examined by transmission electron microscopy (TEM) and the tetragonal phase was imaged using standard dark field techniques.
Domain structures in PbZr0.95 Ti0.05O3
Authors: Kuroda K. , Heuer A. H.
Published: June 2020

Lead zirconate titenate (Pb(Zr,Ti)O3, PZT) is a well known piezoelectric substance. Three phases have been reported in modified PbZr0.95Ti0.05O3 (PZT 95/5) bodies -- a low temperature rhombohedral ferroelectric phase (FR1), a high temperature rhombohedral ferroelectric phase (FR2) and a cubic paraelectric phase (PC). A pressure induced ferroelectric to antiferroelectric phase transformation has also been reported in modified PZT 95/5 ceramics. These phase transformations are of technological importance, as this ceramic has practical applications as a power source in which large quantities of charge are released by shock wave depolarization.

Both as-fired and pressure de-poled samples of PZT 95/5 ceramics with 0.8% Nb were investigated by transmission electron microscopy. Specimens for electron microscopical study were prepared from thin sections, which had been sliced by diamond saw and then mechanically polished with 600 grit SiC paper followed by diamond polishing to about 100 μm thickness. These specimens were then argon ion milled to electron transparency; a liquid N2 cooled stage was used to try and prevent the occurrence of phase transformations due to heating during ion beam thinning. Special care was also taken to minimize beam heating during electron microscopical observation.
Analytical electron microscopy of TiB2 implanted with 1 MeV nickel
Authors: Sklad P. S. , Anqelini P. , Lewis M. B. , Houston J. T. , McHargue C. J.
Published: June 2020

Recently a series of studies has been undertaken to determine the effect of ion implantation on the properties of structural ceramics. In the technique energetic ions impinge on the surface of the material displacing atoms, creating various types of point defects, and finally come to rest in the near-surface region. Because of the nature of these processes it is possible to introduce an element into the substrate to a concentration level much higher than normal equilibrium would allow. The present study is concerned with the microstructure produced by implanting TiB2 with 1 MeV nickel ions.

Polycrystalline samples of TiB2 were implanted at ambient temperatures with 1 MeV Ni+ ions to a fluence of 1 × 1017 ions/cm2. The implanted samples were cut into pieces approximately 1 mm × 2 mm × 5 mm and pairs were glued together with the implanted surfaces facing each other. Slices ∼250 μm thick were then cut, mechanically polished to ∼75 μm, mounted on copper washers, and argon ion milled. This procedure allowed examination of the implanted layer in cross section. The TEM specimens were then examined in a JEM 120CX equipped with a Kevex 5100 x-ray energy dispersive spectroscopy (EDS) system interfaced to a PDP-11/34 computer and peripherals.
Scanning electron beam lithography
Authors: Broers Alec N.
Published: June 2020

This paper discusses the role of scanning electron beam lithography in semiconductor microcircuit production and in the experimental fabrication of devices in the laboratory. It also describes the electron optical equipment developed for these applications.

Electron beam lithography has found an important place in integrated circuit production through its ability to produce structures without masks, rather than because it can produce high resolution. Resolution, however, has been important in research and development where electron beams have been used to produce smaller devices than any other method. Many early micron and sub-micron large scale integration devices were built first with electron beams, and structures as small as a few tens of nanometers have been made for electrical characterization.

Optical methods are generally more economical than electron beams for the routine production of microcircuits because exposure rates are higher and system costs are lower. Resolution with optical lithography is adequate for all devices likely to be in production in the next few years (minimum linewidth 0.75μ - 2μ) so electron beams at present only offer an advantage in fabricating masks, or in exposing customized wafers where masks are not replicated a sufficiently large number of times to offset their cost.
Electron beam resist systems: A critical review of recent developments
Authors: Watts M.P.C.
Published: June 2020

The aim of this paper is to critically review the latest commercial and scientific resist developments in the light of the needs of the semiconductor industry in direct write applications. These needs can be expressed as a set of usable ranges for sensitivity, resolution, and process compatibility, most notably dry etch resistance. The resist sensitivity needed for tolerable throughput varies from 0.5uCoul/cm2to 20 uCoul/cm2depending on the machine being used. Submicron resolution is now a necessity (0.1-1.0 um) because circuits with 1-2 um features are being made using optical lithography.

The resolution limit of a resist is difficult to measure because resolution depends critically on the “image quality” (beam size/shape). Furthermore, for a given critical dimension to be used in a VLSI Si process, that dimension must be reproducible to within tight statistical limits, eg., for Hewlett-Packard's NMOS process the requirement is 1.5um lines, 1um spaces with a 3σ of +/− 0.25um (99.9% confidence limit). With these caveats, SEM's of resolution test paterns can be used as a guide to working resolution.
Nanolithography
Authors: Isaacson M. S.
Published: June 2020

In both science and technology there arises the need to fabricate structures on a scale < 100 nm. For example, the possibility for patterning material at the sub 100 nm scale may be useful for producing quasi two dimensional crystals (eg. 1), while the ability to construct fine metal wires ≈ 10 nm in lateral dimension is of interest in studying electron localization phenomena (a review of techniques and applications can be found in ref. 2). Because of the range of possible applications of nm scale structures, it was felt instructive to look into some of the size limits of patterning material using electron beam technology. The approach chosen has been to investigate new materials that may be useful as resists at the nm size scale and to extend existing technology which relies heavily on large molecular weight polymer resists as the mask in which the electron beam pattern is imprinted.
Reflection electron microscopy (REM) observation of monatomic steps and <133> steps of GaAs(110) surfaces
Authors: Hsu Tung
Published: June 2020

Previous REM observations of atomic steps have shown that higher steps on crystal surfaces produce stronger contrast in REM images. Also observed with REM method was that a screw dislocation can be identified by a terminating step and a strong strain field contrast. Other methods have concluded that for the GaAs(110) surface, both monatomic steps withheight (where a is the lattice constant or 5.65Å) and steps of twice that height arepossible.

A step that ends at a screw dislocation must be ofhigh, corresponding to one unit cell in the (110) direction. Consequently, astep must show lighter contrast than the one that ends at a screw dislocation, provided that the imaging conditions are the same for both. This result is shown in Fig. 1.a. Step 1 ends at a screw dislocation; therefore, step 2, which is lighter, must be one atom high.
Lattice imaging of CdS/CdTe solar cell interface
Authors: Yamashita T. , Werthen J.G. , Bube R.H. , Sinclair R.
Published: June 2020

The structure of electrically characterized CdS/CdTe solar cell interfaces has been analyzed by high resolution lattice imaging. The effects of CdTe substrate orientation and surface preparation on the subsequent growth of CdS and the structure at the interface were investigated. The CdS film was deposited on a p-CdTe substrate by e-beam evaporation, and the resulting structure was electrically characterized. The TEM specimens were prepared in cross-section, and ion-milled to electron transparency. A Philips EM400ST microscope with a point resolution of ∼3.5 Å was used for lattice imaging. Chemical identification of the deposited layer was always made by EDS prior to any structural analysis. The lattice images were obtained in the CdTe <110> projection, and 19 beams (out to (004) reflections) were admitted through the objective aperture to form the image.
A Fourier-transform spectrometer for infra-red cathodoluminescence in TEM
Authors: Spence J.C.H. , Isenman J.
Published: June 2020

The study of the electronic structure of deep states associated with isolated, well characterised extended defects in semiconductors requires the use of a cathodoluminescence apparatus for TEM in the wavelength range 1-50 microns (1.2 - 0.02 eV). This would also allow the study of the III-V alloys and their defects used for I.R. emitters and lasers. Preliminary results using a grating spectrometer have been obtained by Petroff, however experience from Astronomy indicates that the Fellgett + Jacquinot advantage obtainable using Fourier Transform Infrared Spectroscopy (F.T.I.R.S.) is important for weak sources and noisy detectors. (See Davidson who has compared both techniques in SEM).

The crucial design problem in the 1-10 micron range is the mirror movement in the Michelson Interferometer, which must be reproduceably positioned with submicron accuracy over a one centimeter range.
TEM studies of ultra-rapid solidification phenomena in semiconductors
Authors: Cullis A. G.
Published: June 2020

The annealing of semiconductors by use of short, Q-switched laser radiation pulses has been intensively studied over the last few years. The basic mechanism underlying the annealing behaviour is transient (⁓-5-500nsec) surface melting. Melt depths are typically 100-5000Å and high resoldification velocities in a range from less than 1m/s to greater than 20m/s are achievable. These velocities are about five or six orders of magnitude greater than those attained during, for example, conventional crystal growth. Therefore, new high speed solidification phenomena are now amenable to study. The present paper will focus on the behaviour observed under the most extreme conditions and, indeed, crystal growth breakdown and amorphization processes will be described. The solidification characteristics of elemental Si will be compared with those of other semiconductors; namely the compound materials GaAs and GaP. The fundamental role of electron microscope studies in this work will be emphasized.
A cathodoluminescence detection system for TEM/STEM
Authors: Yamamoto N. , Spence J.C.H. , Hazelton D. , Higgs A. , Bergh M.
Published: June 2020

The ability to correlate near-atomic resolution TEM images of defects with their cathodoluminescence (CL) spectra holds promise as a powerful technique for the study of the electronic structure of defects in semiconductors. We have constructed a CL detection instrument fitted to a Philips 400T electron microscope, similar to that described by Roberts, as shown in Fig. 1. The instrument uses an ellipsoidal mirror for light collection allowing operation in the TEM, STEM and REM modes in a relatively clean vacuum, and is compatible with the ELS and EDS modes. The ellipsoidal mirror was designed to collect the maximum amount of emitted light within the limitations of the spacing between the specimen holder and the upper pole piece of the twin lens, as shown in Fig. 2 and 3. The length of the major axis is 61.2 mm and that of the minor axis is 12.1 mm.
Arsenic segregation in polysilicon
Authors: Batson P.E. , Grovenor C.R.M. , Smith D.A. , Wong C.
Published: June 2020

In this work As doped polysilicon was deposited onto (100) silicon wafers by APCVD at 660°C from a silane-arsine mixture, followed by a ten minute anneal at 1000°C, and in one case a further ten minute anneal at 700°C. Specimens for TEM and STEM analysis were prepared by chemical polishing. The microstructure, which is unchanged by the final 700°C anneal,is shown in Figure 1. It consists of numerous randomly oriented grains many of which contain twins.

X-ray analysis was carried out in a VG HB5 STEM. As K α x-ray counts were collected from STEM scans across grain and twin boundaries, Figures 2-4. The incident beam size was about 1.5nm in diameter, and each of the 20 channels in the plots was sampled from a 1.6nm length of the approximately 30nm line scan across the boundary. The bright field image profile along the scanned line was monitored during the analysis to allow correlation between the image and the x-ray signal.
Memory disc defect characterization using SEM and energy-dispersive x-ray analysis
Authors: Bass R. A. , Brar A. S.
Published: June 2020

In this era of computers, users of storage devices are requesting increased quantities of storage while maintaining or reducing the size of the package. This has meant a reduction in the size of a data bit and increased the susceptability of the media to microscopic defects, which occur in many shapes and sizes and at all stages of media processing. These processes are the machining of the raw substrates, coating the substrates, polishing the media and assembling the media in modules.

In the past many of these defects could be overlooked since they didn't introduce missing bits in the read write process. The reason for this was the fact that the recording did not require a high track per inch or bit per inch packing density. Since all media specifications include requirements dealing with the quantity of missing bits or extra bit errors and their sizes; a study of media defects was implemented and the results are presented in this paper.
Microstructure and defects of antigorite
Authors: Spinnler G. E. , Veblen D. R. , Buseck P. R.
Published: June 2020

Antigorite, one of the three species of the serpentine group of minerals is characterized by a corrugated structure made up of layers composed of tetrahedrally and octahedrally coordinated sheets (Fig. 1). This modulated structure model was proposed by Kunze in 1956, and since that time has generally been accepted to account for the x-ray diffraction features of antigorite. Typically, diffraction patterns of antigorite yield an a dimension of ∽40 to 50A, whereas the same dimension of lizardite, the flat serpentine mineral, is ∽5.3A. HRTEM images confirm the basic corrugation of the structure of antigorite. This study reveals both the modulation of the antigorite structure as well as several previously unrecognized nonperiodic features of a particular antigorite.

Classically the serpentine group of minerals has been divided into three distinct species based on their structures: lizardite, antigorite, and chrysotile, a cylindrical structure (Fig. 1). The compositional range of lizardite and chrysotile overlap, whereas antigorite has a small but significant deficiency in octahedral cations and OH owing to the reversal of polarity of the tetrahedral sheets.
Carbon analysis in reactor pressure vessel steels
Authors: de Hodgins O.C. , Shriver B.L. , Lawless K.R.
Published: June 2020

The effect of neutron irradiation on the notch ductility transition temperature (NDTT) of A533B steel is known to be affected by the activity of the carbon atom which would be affected by its nearest neighboring substitutional atom, that is, silicon, manganese, etc. The high carbon activity resulting from increased nickel and silicon promotes the formation of vacancy complexes which produce irradiation hardening and, therefore, higher NDTT shifts.

The present study has been undertaken to clarify the role of carbon and impurities in A533-B steel in the mechanism of neutron embrittlement, two specimens of A533-B pressure vessel steels differing in radiation sensitivity have been examined using transmission electron microscopy. The study showed that the carbon-vacancy complex in iron (ferrite) has a carbon atom positioned a finite distance from the vacancy along a <100> line. In some cases martensite was found, in others, a combination of martensite with ferrite.
Phase changes in a laser-alloyed Fe-5Cr steel
Authors: Padmanabhan R. , Wood W. E.
Published: June 2020

Laser surface alloying is a relatively new method to modify metal surfaces. A suitably applied metal coating and an underlying metal substrate are rapidly melted by a high power, continuous laser beam. The resultant melting, mixing and rapid solidification can be controlled to form an alloyed fusion zone at the surface with the desired mechanical properties.

In this work, Ni-Cr and Ni-Cr-WC metal powders were thermally deposited on a Fe-5Cr steel. Coating parameters were adjusted to achieve desired coating thicknesses. Laser processing was carried out with a continuous CO2 laser beam capable of power densities up to 108 watts/sq.cm. to alloy the metal powder with the base material. Power density, scan rate, spot size and other parameters were all controlled to produce penetration depths of up to 850μm (Table 1). Interpass steps were adjusted to produce both overlapping and discrete fusion zones.
Comparison of residual microstructures in stainless steel after very high pressure shock deformation
Authors: Murr L.E. , Staudhammer K.P. , Johnson K.A. , Olinger B.W.
Published: June 2020

It is now well documented that the explosive shock hardening of 304 and other 300-series stainless steels (which has been reported over a period of nearly two decades) is due in large part to the formation of deformation twins or twin faults. It has been shown in fact that for plane-wave shock loading where the sample is subjected to a pure, compressional shock wave, the hardening saturates with pressure and declines at pressures near or above 1 megabar (>100 GPa) due to thermal effects.

In experiments involving plane-wave shock loading and which employed a flyerplate technique, each test at a specific pressure or pulse duration involved a separate explosive event and required difficult and elaborate experimental arrangements. In some respects this was a convenient arrangement because thin sheets could be sandwiched in these assemblies, providing a convenient regime for transmission electron microscopy of the shock-induced microstructures.
In situ precipitation of θ on A1 in the Al-Cu system
Authors: Clark W.A.T. , Smith D. A.
Published: June 2020

Precipitation in the Cu-Al system can be in several forms, some of which, such as the θ ", θ', and θ phases of CuAl2, have been extensively investigated by both X-ray and TEM methods (see e.g. 1). In general, the precipitation sequence has been systematically controlled by ageing supersaturated solutions of Cu in Al for specific times at temperatures chosen to lie within the upper and lower solvus lines of the required phase. Specimens for TEM were then prepared by standard techniques. In cases where precipitation was carried out in situ, using a hot-stage in the TEM, nucleation at the foil surfaces has appeared to play a prominent role, and precipitation within the foil is, for the most part, suppressed. In this investigation an additional feature is incorported, namely surface diffusion of Cu into a pure Al film, which then leads to the formation of CuAl2 θ-phase precipitates.
The 'well-known' theory of electron image formation
Authors: O'Keefe M.A. , Saxton W.O.
Published: June 2020

A recent paper by Kirkland on nonlinear electron image processing, referring to a relatively new textbook, highlights the persistence in the literature of calculations based on incomplete and/or incorrect models of electron imageing, notwithstanding the various papers which have recently pointed out the correct forms of the appropriate equations. Since at least part of the problem can be traced to underlying assumptions about the illumination coherence conditions, we attempt to clarify both the assumptions and the corresponding equations in this paper, illustrating the effects of an incorrect theory by means of images calculated in different ways.

The first point to be made clear concerning the illumination coherence conditions is that (except for very thin specimens) it is insufficient simply to know the source profiles present, i.e. the ranges of different directions and energies (focus levels) present in the source; we must also know in general whether the various illumination components are coherent or incoherent with respect to one another.
High-resolution observations of PbS adsorbed structures on Mg (00.1) surface
Authors: Tanaka N. , Mihama K.
Published: June 2020

Characteristic surface structures and adsorbed structures of metals and semiconductors have been elucidated by reflection electron diffraction techniques such as LEED and RHEED. These techniques, however, can not give the information about the atomic arrangements or adsorbed sites in a direct way. The present work is the first trial of observing the adsorbed structures of PbS grown on Mg (00.1) surfaces with atomic resolution by using transmission electron microscopy. For such trials, the specimen preparation is the most important problem which decides the success of the observations. Especially, clean, flat and thin (∽10nm) substrates should be prepared.

The present specimen substrates are Mg‐platelike particles prepared by gas evaporation technique. The procedure of the specimen preparation is as follows: Mg-platelike particles (thickness ∽ 20nm) are prepared by the evaporation of Mg ribbon in 10 Torr of argon and gathered on a perforated carbon films. After re-evacuation down to 1 × 10-8 Torr of the chamber, PbS of less than 1 nm in mean thickness is deposited on the Mg-plates.
Development of ultra high resolution analytical electron microscope ISI-EM-002A
Authors: Yanaka T. , Yonezawa A. , Oosawa K. , Iwaki T. , Suzuki S. , Nakamura O. , Watanabe M.
Published: June 2020

Total design concept of EM-002A is to realize the following essential performance, that is, 1) attainment to ultimate high resolution as the conventional electron microscope, 2) complete compatibility of the high resolution mode and the analytical mode, 3) identification of the analyzed region and the observed image with atomic-level resolution, 4) observation of ultra fine structure of the biological specimen with maximum high contrast and so on.

[Electron source] Accelerating voltage ranges from 20kV to 120kV in 6 steps Double Cockroft-Walton circuit is used as the high voltage generator and the high frequency ripple voltage is reduced to 0.1V. Electron gun assembly is composed of high voltage alumina insulator, whose shape is so well designed as to suppress micro-discharge to the negligible order.

[Objective lens and specimen chamber] The objective lens is a strong symmetrical lens where the specimen chamber is located between the symmetrical upper and lower objective lens magnetic circuits. The objective lens has two powerful pole pieces, one being used for the ultra high resolution mode and the other for the standard mode.
Analytical electron microscopy of zeolites
Authors: Lyman C. E.
Published: June 2020

Zeolites are crystalline aluminosilicates with regular arrays of uniform pores or channels ranging in size from 0.3nm to l.Onm depending on the specific structure and composition. Synthetic zeolites are an important class of technological materials with a wide range of selective adsorption, ion exchange, and catalytic properties. Catalytic properties of zeolites are often related to the silicon-- ttoo-aluminum atomic ratio; however, conventional microprobe analysis of zeolites has been limited to crystals much larger than the l-5μm size used in practice.

Zeolite A is known to have a Si/Al ratio near unity since it contains the maximum aluminum content possible in a tetrahedral aluminosilicate framework. Particles of zeolite Na-A were embedded in epoxy and 80nm-thick sections were cut with a diamond knife and collected on carbon coated Cu grids. Analyses across zeolite particles were performed in a Vacuum Generators HB-501 STEM fitted with a Kevex x-ray detector. Because this material damages in the electron beam, x-ray spectra were taken while scanning the beam in a raster about l00nm x l00nm.
Compositional and structural characterization of isolated Pb-Bi microcrystals co-vapor deposited onto amorphous carbon
Authors: Gile W. W. , Jesser W. A.
Published: June 2020

Recent interest in heterogeneous nucleation of binary alloys requires a knowledge of the structure and composition of deposits. Analytical electron microscopy and x-ray microanalysis is well suited to obtaining such information and has already been applied to the overall characterization of a collection of isolated microcrystals. The methods for performing this characterization are well documented; however, the application of the technique to the determination of composition of individual microcrystals as a function of crystal size is less well documented. In addition to the fundamental interest such information provides, it is of practical importance in such disciplines as supported alloy catalysts where a size-dependent composition and/or structural behavior may change both the selectivity and reactivity of a catalyst.

The specimens in this investigation were prepared by co-vapor deposition of Pb and Bi onto hot amorphous carbon substrates between 150°C and 250°C. The Pb and Bi were co-evaporated from separate filaments of Mo and Ta, respectively, or an alloy of PbBi was evaporated from a single filament of tantalum with no significant difference occurring in the deposits prepared by either method.
Three-dimensional image reconstruction of rigor crossbridges in insect flight muscle (IFM)
Authors: Taylor K. , Cordova L. , Reedy M.C. , Reedy M.K.
Published: June 2020

Dorsal longitudinal IFM from the water bug Lethocerus indicus, was rigorized by glycerination. Fiber bundle 958 retained a good rigor x-ray diffraction pattern after a 5 step fixation embedding sequence which included glutaraldehyde-tannic acid fixation, OsO4-UrAc staining, ethanol dehydration and Araldite embedding.

The MYAC single filament layer of insect flight muscle contains alternating thick and thin filaments and is found isolated within longitudinal sections about 250Å thick. For our 3-D reconstruction we selected a MYAC region which appeared homogenous (both sides equal) over nearly 3/4 of a half sarcomere. Two tilt series ranging through ±60° of tilt in 10° steps were obtained, with tilt axis parallel to the filament axis in one and perpendicular in the other. Fourier transforms were calculated from 256x256 point arrays.

The tilt data were combined using procedures similar to those used for 2-D crystalline arrays except that we obtain both amplitudes and phases from the image data.