bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on a ph related zone phenomenon in erythrocytes
Authors: Timme Alan H.
Published: June 2020

In 1967 Baker reported the occurrence of a zone of dense material adjacent to the inner leaflet of the unit membrane of erythrocytes exposed to buffers with a pH 4.5. It was postulated that this arose because the haemoglobin, positively charged at that pH, was attracted to the negatively charged membrane.

In an attempt to elucidate the mechanisms underlying the formation of the zone, fresh human erythrocytes were washed for 15 minutes at room temperature in citrate phosphate buffers in which the pH ranged from 4.0 - 7.4, or in a standard preservative solution, Acid Citrate Dextrose (ACD), pH 5.0. Paired samples were subsequently washed in buffer at pH 7.4 for 10 minutes to assess the possible reversibility of any changes produced. The cells were fixed in 2.5% glutaraldehyde in 0.1 m cacodylate buffer at the same pH as the washing buffer for one hour and then processed in two ways: Some were post-fixed in OSO4, The cells were stained with 0.5 - 1% Alcian Blue 8 G S in cacodylate buffer pH 7.0 for 15 - 30 minutes.
Receptor mobility and the cytoskeleton in some human leukemic cells
Authors: Temmink J.H.M.
Published: June 2020

Introduction. Lymphoid cells will, under certain conditions, exhibit striking exemples of surface receptor movement upon exposure to specific ligands. The receptors will first assemble in a few small surface areas (patching) and eventually aggregate at one pole of the cell (capping), leaving practically no receptors of the same specificity elsewhere on the cell surface. For a number of reasons cytoskeletal elements, like microtubules and microfilaments, are thought to play an important role in the movement of the cell surface receptors. However, the exact mechanism by which the cytoskeleton has its facilitating or inhibiting effect on receptor mobility is still largely a matter of speculation.

During an investigation on non-Hodgkin lymphoma's we obtained leukocytes from three patients with clinically different leukemia's, i.e. hairy cell leukemia (HCL), prolymphocytic leukemia (PLL), and chronic lymphocytic leukemia (CLL). These gave different results in capping tests with Concanavalin A (ConA) and with antibodies against total Ig (Alg).
Contractile proteins in the sieve tubes and laticifer cells of some sensitive mimosa species
Authors: Artemίsia Arraes-Hermans M. , Dalla Bernardina E. L.
Published: June 2020

The purpose of this paper is to review our previous work with HMM binding and to demonstrate with some new findings that this technique can be used effectively to determine changes in the organizational states of the actin-like microfilaments which are responsible for cytoplasmic streaming in laticifer cells and for conduction of the stigmotropic stimulus in the cytoplasm of mature sieve elements. The species used were Mimosa rixosa Mart., M. asperata Linn., and Mimosa laticifera Rizz.

The technique used was negative coloration of phloem exudate and cytoplasmic suspension of latex. We have identified actin filaments in phloem exudate and latex of higher plants on the basis of filament morphology, reaction of the filaments with rabbit skeletal muscle HMM to form arrowhead complexes, and the reversibility of the arrowhead reaction on addition of pyrophosphate. This is the first report dealing with the presence of actin in sieve elements. Some of the microfilament structures are specific components of the cytoplasm of mature sieve tubes.
The effect of daily prenatal gamma irradiation on ovarian cortex of beagle pups
Authors: Sanderson Margaret H. , Seed Thomas M.
Published: June 2020

Breeding experiments using beagle dams that had been exposed in utero to daily 60Co gamma radiation at a rate of 5. 0 R have shown that these animals are unable to bear young. A previous report has indicated that this dose rate, administered daily to the developing fetus for the entire gestation period, causes profound gonadal damage expressed as an anoogonial-afollicular ovarian syndrome in the newborn, and functionally as radiation sterility in the adult. To evaluate radiation damage to extrafollicular areas of ovaries in the developing fetus at the ultrastructural level, pregnant normal dams were exposed daily to 60Co gamma rays at dose rates of 2. 5 or 5. 0 R for the duration of pregnancy. The pups were assigned to groups at birth, and their ovaries, as well as those of controls of similar ages, were excised surgically on postnatal days 5, 10, 17, 24, and 44. Cortical areas of each gonad were processed for electron microscopy using standard methods.
Zinc iodide-osmium tetroxide reaction: its effect on the synaptic vesicles in locust neuromuscular junctions and its chemical basis
Authors: Reinecke M. , Walther Ch.
Published: June 2020

The zinc iodide-osmium tetroxide reaction (ZIO) was first used in neurobiological research by Maillet (Bull. Ass. Anat. 53, 233; 1968). Subsequently several authors have shown that, under appropriate conditions, ZIO stains mainly the interior of synaptic vesicles. The substrate of this reaction is under discussion, since ZIO can also react with other subcellular structures in a variety of tissues, e. g. mitochondria, endoplasmic reticulum, dictyosomes and lysosomes. Additionally, in vitro substances as different as some aminoacids, catecholamines, aldehydes and phospholipids (Pellegrino de Iraldi, Experientia 33, 1; 1977) can yield black precipitations with ZIO.

Our studies were done with the motor nerve terminals at the femoral retractor unguis muscle of the locust (Locusta migratoria). These terminals are chiefly the endings of excitatory motoraxons and are characterized by the presence of electron lucent vesicles and by an accumulation of mitochondria.
A novel technique for the isolation of transverse tubular membrane from dystrophic skeletal muscle
Authors: Sabbadini Roger , Scales Donald , Nixon Cecelia
Published: June 2020

IntroductionA particularly high fraction of T tubular membrane is apparent in standard isolations of microsomes derived from dystrophic muscle. We describe here a method for separating vesicles of T tubules from vesicles of sarcoplasmic reticulum (SR). The method assumes that only SR membranes are capable of ATP-dependent Ca2+transport, and in the presence of the precipitating anion oxalate, the buoyant density of oxalate- filled SR exceeds that of non-calcium transporting membranes. These latter microsomes are tentatively identified as T tubular membrane based on both morphological and biochemical observations.

MethodsAs described previously microsomes were isolated from dystrophic chicken pectoral is muscle. The crude microsomes were incubated for 10 min. at 37°C in a medium containing 20 mM MOPS (pH 6. 8), 2 mM CaCl2, 2 mM EGTA, 5 mM Mg-ATP, 80 mM K-oxalate. This was cooled to 5°C and a 30 ml aliquot was layered on a 4 ml cushion of 52% sucrose, 20 mM MOPS. The microsomes were centrifuged for 45 min. at 82, 500 g in a Beckman L5-50 ultracentrifuge.
Electron microscopical study on collagen of chondrosarcoma
Authors: Takagi Katsumasa , Honda Itsuo , Kitagawa Toshio , Usuku Gentaro
Published: June 2020

The histological identification of the malignancy of a cartilaginous tumor is not always simple. The ultrastructural structure of the cartilage has been described in numerous reports but there are few dealing with chondrosarcoma. Present authors have been studying to discover definite characteristics of chondrosarcoma. In this study, we hope to discover the characteristics of chondrosarcoma by concentrating on the collagen fibers which are one of the main components of chondroid tumor.

Ten cases of chondrosarcoma ranging from 14 to 65 years of age, were examined using both transmission electron microscope and scanning electron microscope, and their structures were compared with other chondroid tissues, taken from non-malignant cartilaginous tumor, normal conditioning articular cartilage, and the meniscus of the knee joint. Small pieces of the specimens were fixed in 3% glutaraldehyde buffered with Millonig's phosphate buffer, post-fixed in 1% osmium tetroxide and embedded in Epon 812. Sections cut by LKB ultramicrotome were stained by uranyl acetate and lead citrate and examined with an AKASHI-TRS-80 electron microscope. The preparations for the scanning electron microscopy were coated with carbon and gold after the critical point drying method.
Compositional mapping with the electron probe microanalyzer: Capabilities, limitations, opportunities
Authors: Newbury Dale E.
Published: June 2020

Compositional mapping by electron probe microanalysis is one of the most highly developed techniques for the characterization of laterally inhomogeneous microstructures on a micrometer scale. X-ray dot mapping, or area scanning, has been a qualitative analysis tool since the earliest development of the scanning electron microprobe. Quantitative compositional mapping has been developed in the last five years by devising procedures to perform under computer control a complete electron probe analysis at each beam location in a scanned field. Energy dispersive spectrometry (EDS), wavelength dispersive spectrometry (WDS), or combined EDS/WDS can be used for data acquisition in the mapping mode, permitting simultaneous mapping of 10 or more constituents. All corrections applied in the conventional single point quantitative analysis procedure are included in the compositional mapping procedure: deadtime correction, spectral deconvolution, standardization (k-value measurement compared to a known standard), and matrix correction [ZAF, ϕ(pz), etc.]. Additional corrections for instrumental effects on WDS defocussing or EDS collimation are applied as necessary.
Compositional mapping by electron energy loss spectroscopy
Authors: Leapman R.D. , Hunt J.A.
Published: June 2020

Compositional maps of a thin specimen can be obtained using electron energy loss spectroscopy (EELS) to measure the two-dimensional distribution of inelastic scattering processes. These maps may be acquired both in the energy-filtering transmission electron microscope (EFTEM) and in the scanning transmission electron microscope (STEM). An advantage of EFTEM is that data from large numbers of pixels are collected simultaneously making the technique favorable for detection of high local elemental concentrations. However in the EFTEM images at different energy losses must be acquired sequentially, complicating the analysis of weak spectral features which require careful subtraction of the background intensity. Early attempts to utilize the STEM for EELS mapping were limited by the performance of serial detectors. The availability of parallel detectors and inexpensive PC-type computers with sufficient storage and speed has generated new interest in using the STEM for EELS elemental mapping. In particular the concept of EELSspectrum-imaginghas been introduced by Jeanguillaume and Colliex.
Retroviruses isolated from cell cultures of human testicular germ cell tumors
Authors: Smith G. C. , Bronson D. L.
Published: June 2020

Human testicular germ cell tumors, which include embryonal carcinoma (EC), teratoma (TM), yolk sac carcinoma (YSC), and choriocarcinoma (ChCa), depict stages of embryogenesis. Differentiation of primitive EC cells is a pathway by which TM, YSC, and ChCa develop. Human EC cells in vitro produce retroviruses, at low frequency, which are morphologically identical to the human placental retrovirus. These viruses have not been previously found in YSC, TM or ChCa cells grown in culture. Due to low virus yield in EC cultures, studies of virion properties have been impeded. We have developed a ChCa cell line by cultivating mixed germ cell tumors in which ChCa was identified histologically. We describe the development of a cell line producing retrovirus particles in markedly higher frequency than those observed with human EC cells.
Antioxidant suppression of blood-brain barrier disruption and demyelination in experimental optic neuritis
Authors: Ann Ellis E. , Guy John R. , Fitzsimmons Jeffrey R. , Beck Barbara L.
Published: June 2020

Hydrogen peroxide (H2O2) has been shown to play a major role in disruption of the blood-brain barrier (BBB) and demyelination in experimental allergic encephalomyelitis (EAE), an animal model for multiple sclerosis (MS). Reactive oxygen species, H2O2 and superoxide, are discharged by inflammatory cells that infiltrate the central nervous system (CNS) in FAE. Hydrogen peroxide can be directly toxic or can be converted to hydroxyl radical and induce peroxidation of lipids such as myelin. Catalase and glutathione peroxidase are antioxidant enzymes which detoxify H2O2 to O2 and H2O.

Strain-13 guinea pigs were sensitized with myelin basic protein and in vivo permeability of the BBB was monitored by serial magnetic resonance imaging (MRI) with gadolinium-DTPA (Gd-DTPA) and the Dixon method for suppression of orbital fat. MRI was initiated three days after antigenic sensitization and performed at four or seven day intervals thereafter. All sensitized animals developed Gd-DTPA enhanced lesions, indicative of permeability of the BBB, at 3-7 days after antigenic sensitization.
Ultrastructure of transplanted schistosome sporocysts in incompatible snails
Authors: Rivera E.R. , Jourdane J.
Published: June 2020

The tropical parasitic disease schistosomiasis haematobium requires the snail vector Bulinus truncatus to successfully complete its life cycle. While in the snail, the parasite exists as a cercarial producing sporocyst. The infection of snails by the parasite is very specific, different subpopulations (strains) of parasites are not always compatible with snails from different geographic regions. It is not always known if the incompatibility is due to failure of penetration of snails by parasites or to subsequent destruction of sporocysts by infected snails. In these experiments, sporocysts from compatible sporocyst-snai1 infections were surgically transplanted into snails not compatible with the parasite.

Egyptian snails (B. truncatus) which had been infected with the Egyptian strain of Schistosoma haematobium were dissected after five weeks. Sporocysts were removed from the hepatopancreas and surgically implanted into B. truncatus snails from Egypt (compatible), Morocco and Niger (incompatible). After four days, these snails were dissected and the transplanted sporocysts were prepared for electron microscopy. Each sample was also tested for glycogen contents by the Thiery Silver test.
High-Voltage Electron microscopy of Histoplasma capsulatum
Authors: Song M. J. , Edwards M. E.
Published: June 2020

Histoplasma capsulatum (Hc) is a pathogenic fungus frequently involved in lung infections, especially in immunocompromised individuals such as AIDS patients. It has been the subject of numerous investigations by light, transmission, and scanning electron microscopy. However, these studies did not afford a clear picture of the He cell architecture, for which three-dimensional views of the cellular organelles are deemed necessary. For this purpose, we have studied yeast cells of He by means of techniques used in high—voltage electron microscopy (HVEM).

Yeast cells of He grown at 37°C in appropriate culture media were fixed with glutaraldehyde-osmium in cacodylate buffer, dehydrated through an ethanol series and embedded in Epon-Araldite, according to standard procedures. Thick sections (0.25-0.5 μm), picked up on Formvar-coated slot-grids, were stained for 4 h at 50°C with uranyl acetate and lead citrate, and examined under the AEI EM7 Mk 1.2 MV Albany HVEM at an accelerating voltage of 1.0 MV.
Three-dimensional organization of neuronal and glial cell processes as revealed by HVEM stereoscopy
Authors: Kama Kiyoshi
Published: June 2020

The Knowledges on the three dimensional (3D) organization and the morphometrical data of neuronal and glial cell processes are indispensable for the understanding of the function of the CNS.

The light microscope has been widely used for the morphological study of neurons and glia cells however the limited resolution of the light microscope has precluded the precise observation of structural details of the complicated processes of these cells. In addition, the depth of focus of the light microscope is veryshallow. Although the problem of this fault of the light microscope can be overcome by the use of the X-ray microscope which enables imaging of the specimens of 500μm in thickness in the same focal plane the resolution of the X-ray microscope we have developed is about the same range as that of the light microscope. In contrast, the conventional electron microscope provides extremely detailed images of neuropile.
Distinct oscillations in cytosolic and nuclear free calcium in single intact living cells demonstrated by confocal microscopy
Authors: Diliberto P. A. , Periasammy A. , Herman B.
Published: June 2020

Many growth factors stimulate both a rapid increase in free calcium (Ca2+i) and protooncogene expression in cells following binding to their cell surface receptors. Increases in Ca2+i and proto-oncogene expression are thought to be important in the transduction of growth factor binding and regulation of other cellular activities (i.e. mitogenesis), yet a direct role for the interaction of these two growth factor-stimulated events has been lacking. We have previously reported the observation of changes in free calcium in the nuclear region of vascular smooth muscle cells (VSMC) which were temporally and spatially distinct form those of the cytoplasm. We hypothesized that these changes in nuclear free calcium (Ca2+n) might activate gene expression necessary for growth factor activity and thus provide a direct link between growth factor-induced increases in Ca2+n and proto-oncogene expression. That growth factor stimulated alterations in Ca2+n may occur is strengthened by the recent description of an ATP-dependent nuclear Cna2+ pump, an inositol 1,4,5-trisphosphatesensitive Ca2+ pool in liver nuclei and subcellular heterogeneity of Ca2+ transients in voltage clamped vertebrate neurons.
Ultrastructural effects of recombinant human hematopoietic stem cell factor on mast cells and basophils from human CD34+ pluripotent progenitor cells
Authors: Goff J.P. , Kirshenbaum A. S. , Albert J. P. , Kessler S.W. , Zsebo K. M. , Metcalfe D. D.
Published: June 2020

Hematopoietic stem cell factor (SCF) is the product ofSllocus in the mouse and is the ligand for the protooncogenec-kit.The human homologue has recently been cloned and recombinant protein (rhSCF) expressed and purified to homogeneity. rhSCF is synergistic with human cytokines in promoting the proliferation and differentiation of human progenitor cells.

Human mast cells and basophils have been shown to originate from human bone marrow-derived CD34+ pluripotent progenitor cells cultured in the presence of rhIL-3, and develop granule scroll patterns only when cocultured with mouse 3T3 fibroblasts. Mast cells, from CD34+ cells cultured over agarose surfaces, in the presence of rhIL-3 had granules that contained only homogeneously dense material. To determine the effect of rhSCF on the appearance of mast cells and basophils in culture, highly purified human CD34+ progenitor cells were grown in the presence of rhIL-3, rhSCF, or rhIL-3 in combination with rhSCF over agarose surfaces.
New cathodoluminescence spectral analysis and imaging equipment
Authors: Wright P. J.
Published: June 2020

The examination of CL emission can provide a wealth of information from many widely differing materials when irradiated by the electron beam of an SEM. However, the requirements that need to be met by equipment designed to observe these signals differ widely depending on the application for which it will be used. Oxford Instruments have developed two CL systems which, in conjunction with cooling stages, can provide for the needs of the majority of CL researchers.

The first is iciCL and it enables production of true colour digital images from many materials, although its major use has been in the study of geological materials and ceramics. Provision has also been made to allow the acquisition of CL spectra within the range 400 ≤ λ ≤ 700 nm and the generation of false colour and composite images.
A Confocal scanning laser microscopic study of the developing heart
Authors: Chintanawonges C.
Published: June 2020

During heart development myofibrillogenesis and myocyte fiber pattern formation are critical steps in the genesis of a functional four chambered pump. The factors affecting these morphogenetic patterns are complex and include mechanical and chemical regulatory agents. The long range goal of this research is to model the effects of mechanical stimulation on heart development. In order to accomplish this goal, accurate images of the fiber patterns in the myocardium are necessary at various stages of development. In this study, we have used confocal scanning laser microscopy and immunofluorescence staining to visualize the fiber patterns and myofibrils in the developing rat heart. Sprague-Dawley rats at 10-15.5 days of gestation (Plug date was designated as day 0 with noon of plug date being designated as day 0.5) were sacrificed by lethal injection of anesthetic and their embryos were fixed in 2.0% paraformaldehyde in 0.1 M HEPES (PH 7.2) for 4-8 hours at 4°C.
Fluorescence microscopy: A tool for studying the physical chemistry of interfaces
Authors: Stine Keith J. , Knobler Charles M.
Published: June 2020

The technique of fluorescence microscopy, a long-standing, powerful, and still evolving research tool in molecular biology, has recently found application to the study of Langmuir monolayers and to multilayers and vesicles. In this review, the basic instrumentation of fluorescence microscopy will be reviewed and a number of powerful modifications of the technique will be surveyed. Resolution limits of the techniques will be discussed. The technique of fluorescence photobleaching recovery is used to study diffusion rates. Fluorescence polarization microscopy measures orientational distributions and the rotational diffusion of molecules. Total internal reflection fluorescence microscopy can be used to selectively excite fluorophores near an aqueous-glass interface. Spectral resolution is employed in the techniques of fluorescence ratio imaging and multiparameter studies using more than one kind of probe molecule. Improved two-dimensional sectioning is achieved by confocal techniques using laser scanning leading to the realization of three-dimensional fluorescence imaging. After a concise survey of the most prominent biophysical applications, recent work on Langmuir monolayers will be described.
Resolution in photoelectron microscopy
Authors: Rempfer G. F.
Published: June 2020

In photoelectron microscopy (PEM), also called photoemission electron microscopy (PEEM), the image is formed by electrons which have been liberated from the specimen by ultraviolet light. The electrons are accelerated by an electric field before being imaged by an electron lens system. The specimen is supported on a planar electrode (or the electrode itself may be the specimen), and the accelerating field is applied between the specimen, which serves as the cathode, and an anode. The accelerating field is essentially uniform except for microfields near the surface of the specimen and a diverging field near the anode aperture. The uniform field forms a virtual image of the specimen (virtual specimen) at unit lateral magnification, approximately twice as far from the anode as is the specimen. The diverging field at the anode aperture in turn forms a virtual image of the virtual specimen at magnification 2/3, at a distance from the anode of 4/3 the specimen distance. This demagnified virtual image is the object for the objective stage of the lens system.
Observation of extremely thin insulating layers formed on a trench with an ultra-high-resolution scanning electron microscope
Authors: Ogura K. , Teshima J.
Published: June 2020

Observation of extremely thin insulating layers of silicon oxide and silicon nitride formed on a trench with a conventional EE SEM cannot be satisfactorily carried out by the conventional method to mechanically polish and chemically etch the wafer cross section and then investigate the state of layer formation from the uncvenness appearing on the cross section. One reason is that the resolution of the conventional FE SEM is not enough for the observation of several nm thick layers even if they arc etched. Another reason is that true layer thickness may be obscured by chemical etching. Those are why TEMs have been used for the observation of extremely thin insulating layers on trenches with atomic resolution. However, TEM application includes complicated specimen preparation, and does not allow observation of wide field of view. Therefore, the ultra-high resolution SEM (UHR SEM) has recently been used for similar purposes, using a simply cleaved plane of a wafer.
Misfit dislocations in multivariant epitaxy of silver on copper
Authors: Boyne D.M. , Tan E. K. , Dregia S. A.
Published: June 2020

Misfit dislocations are known to accommodate disregistry at interfaces which separate crystals of different orientation and/or lattice parameter. Most studies of misfit dislocations have addressed epitaxial bicrystals in ‘parallel’ orientation relationships (OR), e.g, cube-on-cube in fee systems. Recent work, though, has demonstrated that non-parallel epitaxial ORs are energetically favored in some systems, e.g, (111)/(001) in fee systems of large misfit (∼12%). In these systems coexistence of equivalent variants of the same OR gives rise to ‘multivariant epitaxy’ wherein a film grows in a special polycrystalline form on a monocrystalline substrate. In this study we examine the accommodation of misfit in the special structures produced by multivariant epitaxy of (111)Ag on (001)Cu.
HREM Study of electron-induced surface radiation damage in ReO3
Authors: Ai R. , Fan H.-J. , Marks L. D.
Published: June 2020

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.

ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.
In situ REM imaging of surface processes on ceramic bulk crystals from 300 to 1670 K in a conventional TEM
Authors: Wang Z. L. , Bentley J.
Published: June 2020

Studying the behavior of surfaces at high temperatures is of great importance for understanding the properties of ceramics and associated surface-gas reactions. Atomic processes occurring on bulk crystal surfaces at high temperatures can be recorded by reflection electron microscopy (REM) in a conventional transmission electron microscope (TEM) with relatively high resolution, because REM is especially sensitive to atomic-height steps.

Improved REM image resolution with a FEG: Cleaved surfaces of a-alumina (012) exhibit atomic flatness with steps of height about 5 Å, determined by reference to a screw (or near screw) dislocation with a presumed Burgers vector of b = (1/3)<012> (see Fig. 1). Steps of heights less than about 0.8 Å can be clearly resolved only with a field emission gun (FEG) (Fig. 2). The small steps are formed by the surface oscillating between the closely packed O and Al stacking layers. The bands of dark contrast (Fig. 2b) are the result of beam radiation damage to surface areas initially terminated with O ions.
Determination of interface width using EELS fine structure changes
Authors: Dravid Vinayak P. , Notis M.R. , Lyman C.E.
Published: June 2020

The concept of interfacial width is often invoked in many materials science phenomena which relate to the structure and properties of internal interfaces. The numerical value of interface width is an important input parameter in diffusion equations, sintering theories as well as in many electronic devices/processes. Most often, however, this value is guessed rather than determined or even estimated. In this paper we present a method of determining the effective structural and electronic- structural width of interphase interfaces using low- and core loss fine structure effects in EELS spectra.

The specimens used in the study were directionally solidified eutectics (DSEs) in the system; NiO-ZrO2(CaO), NiO-Y2O3 and MnO-ZrO2(ss). EELS experiments were carried out using a VG HB-501 FE STEM and a Hitachi HF-2000 FE TEM.
Lorentz electron microscopy of magnetic domains in rapidly solidified and annealed Pt-Co-B alloys
Authors: Qiu N. , Wittig J. E.
Published: June 2020

PtCo hard magnets have specialized applications owing to their relatively high coercivity combined with corrosion resistance and ductility. Increased intrinsic coercivity has been recently obtained by rapid solidification processing of PtCo alloys containing boron. After rapid solidification by double anvil splat quenching and subsequent annealing for 30 minutes at 650°C, an alloy with composition Pt42Co45B13 (at.%) exhibited intrinsic coercivity up to 14kOe. This represents a significant improvement compared to the average coercivities in conventional binary PtCo alloys of 5 to 8 kOe.

Rapidly solidified specimens of Pt42Co45B13 (at.%) were annealed at 650°C and 800°C for 30 minutes. The magnetic behavior was characterized by measuring the coercive force (Hc). Samples for TEM analysis were mechanically thinned to 100 μm, dimpled to about 30 nm, and ion milled to electron transparency in a Gatan Duomill at 5 kV and 1 mA gun current. The incident ion beam angle was set at 15° and the samples were liquid nitrogen cooled during milling. These samples were analyzed with a Philips CM20T TEM/STEM operated at 200 kV.
Microstructural characterization of InGaAs/GaAs quantum wells grown at low substrate temperatures
Authors: Sung C.M. , Elman B. , Ostreicher K.J. , Hefter J. , Koteles Emil S.
Published: June 2020

The composition and thickness of InxGa1-xAs/GaAs quantum wells play an important role in the determination of their optical and electronic properties. InxGa1-xAs/GaAs single quantum wells (SQWs) grown at low substrate temperatures with various In compositions (x) and well thicknesses were investigated by reflected high energy electron diffraction (RHEED) and photoluminescence (PL) techniques to determine when the critical thickness for pseudomorphic growth was exceeded. Cross-sectional TEM methods were employed to directly determine the critical layer thickness of InGaAs on GaAs and the presence of the dislocations generated in these layers.

The samples were grown by MBE on semi-insulating (100) GaAs substrates at substrate temperatures of 410°C and 460°C. They consisted of undoped SQWs and barriers in which the well width was varied from 1 nm to 22 nm. The In composition in the well layers was varied from 0.3 to 0.5. The growth rates and In compositions were deduced from RHEED intensity oscillation measurements . Cross-sectional specimens for TEM studies were prepared in the usual manner, by mechanical thinning followed by Ar+ ion milling. A Philips EM400T operated at 120 keV was used to observe the specimens.
Microanalysis of high-dose oxygen-implanted germanium
Authors: Kim M.J. , Zhang Q. , Das Chowdhury K. , Carpenter R.W. , Kelly J.C.
Published: June 2020

High-dose ion implantation is being increasingly used to produce buried oxide layers in silicon for high speed CMOS and VLSI applications. Ion implantation into germanium has been used to control optical properties. Germanium implanted with high dose oxygen is a promising material for photodetectors and solar energy converters. In the present study the structural changes in germanium caused by high dose oxygen implantation, giving low reflectivity in the far-UV and visible, were characterized by HREM and high spatial resolution AEM.

The single crystal n-type germanium {111} wafers were implanted with O+ ions to doses of lx1017 to 1.5xl018 cm-2 at 45 keV. The implantation temperature was estimated to be about 400°C. The absorption behavior of the implanted samples was measured by Infrared (IR) spectroscopy. The compositional profiles of implanted layers were obtained by Rutherford Backscattering Spectrometry (RBS) and position-resolved EELS. Cross-sectional TEM samples for microstructural characterization were prepared by mechanical polishing and ion milling. A Philips 400ST/FEG analytical microscope was used for nanoprobe experiments, at 100 kV. Microstructural investigation was performed using ISI-002B and JEM-2000FX microscopes, at 200 kV.
Characterization of Bulk-Grown Hg1-xcdxTe
Authors: Zuo H. , Griffin R.D. , Janowski G.M. , Andrews R.N.
Published: June 2020

The II-VI semiconducting compounds are of particular interest due to the ability to compositionally tune them to detect infrared radiation in the 0.5 to 30 μm range. With the demand for advanced imaging systems, there is an immediate need for bulk II-VI materials with improved compositional homogeneity and structural perfection. The performance of optical semiconductors is very sensitive to the presence of defects such as dislocations, precipitates, and boundaries.
Microstructure of the Oxidized Surface of Rare-Earth Disilicate - Silicon Nitride Ceramics
Authors: Cinibulk Michael K.
Published: June 2020

Silicon nitride ceramics are being considered for use as structural materials in high-temperature oxidizing environments. Silicon nitride itself is extremely oxidation resistant due to the protective SiO2 layer, which results from exposure to high oxygen partial pressures at elevated temperatures. However, hightemperature exposure of silicon nitride sintered with oxide additives leads to accelerated oxidation attributable to the enhanced oxidation of Si3N4 dissolved in a silicate phase present at the surface. Since diffusion of additive and impurity cations through an amorphous grain-boundary phase from the bulk to the surface oxide scale is rate limiting, obtaining crystalline phases in equilibrium with SiO2 should eliminate the driving force for cation diffusion and improve oxidation resistance. Characterization by electron microscopy of the oxidized surfaces resulting from high-temperature oxidation is necessary to understand and solve these problems.
Electron energy loss spectroscopy of model catalysts: Rh/Ce on silica
Authors: Krause K. R.
Published: June 2020

We have studied Rh/Ce, two important components of the automotive catalytic converter, on silica after high temperature reduction and oxidation with TEM, HREM, XPS, and EELS. Catalyst characterization is complicated by the possible existence of many phases involving the metal and/or support including intermetallics, alloys, and oxides. These phases may be amorphous or very thin crystals, making identification by electron diffraction difficult. Conventional surface science techniques such as XPS can give chemical information but lack the spatial resolution needed to fully characterize the microstructure. Ce containing patches were observed on the silica after reduction and their composition could not be determined by conventional TEM. These patches may be important for Ce promotion of kinetics and we have used EELS to obtain chemical information from individual patches.
Multiple scattering and displacive modulation in the YBa2Cu3O7-δ system
Authors: Zhu Yimei , Suenaga M. , Moodenbaugh A.R.
Published: June 2020

Using transmission electron microscopy, structure modulation associated with electron multiple scattering and diffuse scattering in oxygen reduced, and Fe and Co doped YBa2Cu3O7_δ has been studied. The modulated structure (tweed) exhibits [110] and roughly-periodic lenticular domain images (see Fig.l) and cross-shaped diffuse intensity in diffraction (see Fig.2). The overall diffraction pattern in the [001] zone has a 4-fold symmetry with diffraction intensity which falls off monotonically from one Brillouin zone to the next. Superimposed over each Bragg spot seem to be two cross-streaks of equal length in the [110] and directions.

However, for a diffraction pattern in a high symmetry Laue case, one must consider the possibility of multiple scattering effects, whereby a diffracted electron beam acts as an incident beam. This can complicate diffuse scattering phenomena, even in a thin crystal. Careful inspection of Fig.2 reveals that the shapes of the diffuse scattering are not all identical at all diffraction spots.
Lectin Binding to Human Breast Tumor Cells
Authors: Nordquist Robert E. , Hill Anglin J. , Lerner Michael P.
Published: June 2020

A human breast carcinoma cell line (BOT-2) was derived from an infiltrating duct carcinoma (1). These cells were shown to have antigens that selectively bound antibodies from breast cancer patient sera (2). Furthermore, these tumor specific antigens could be removed from the living cells by low frequency sonication and have been partially characterized (3). These proteins have been shown to be around 100,000 MW and contain approximately 6% hexose and hexosamines. However, only the hexosamines appear to be available for lectin binding. This study was designed to use Concanavalin A (Con A) and Ricinus Communis (Ricin) agglutinin for the topagraphical localization of D-mannopyranosyl or glucopyranosyl and D-galactopyranosyl or DN- acetyl glactopyranosyl configurations on BOT-2 cell surfaces.
Morphometry of T219 Soybean Chloroplasts During Initial Exposure to Light
Authors: Crang Richard E. , Baxter William D.
Published: June 2020

Strain T219 soybeans exhibit three genetically determined levels of photosynthetic pigments yielding plants characterized as dark green (DG), light green (LG) and lethal yellow (LY). Rapid light-induced changes in plastid morphology have been demonstrated (e.g. 1). Our previous observations indicated that the amount of change in morphology of T219 plastids following illumination after 12 hr. darkness varied in direct relation to the amount of chlorophyll present. DG plastids changed more than LG while LY plastids showed virtually no change (2). Change was characterized by flattening, loss of volume and diminution of starch immediately following illumination with a gradual recovery after 10-20 min. of light. In the present study changes in surface area of plastid boundary membranes and thylakoids were analyzed for all three types of strain T219 plants during initial exposure to light.
Ultrastructural Changes in Schwann Cells of Peripheral Nerve of Diabetic Mice
Authors: Hanker J. S. , Carson K. A. , Ambrose W. W. , Yates P. E. , Bossen E. H.
Published: June 2020

At 8 to 11 months of age inbred mice (C57BL/KsJ-db, The Jackson Laboratory) with an autosomal recessive disease resembling human diabetes mellitus show inconstant and intermittent symptoms of a sensory ataxia which is manifest by flexion and adduction of the hind limbs. When their peripheral nerves such as trigeminal ganglion and sciatic nerve are compared with those of unafflicted littermates, a marked proliferation of Schwann cells is observed. It was, therefore, of interest to compare ultrastructurally the sciatic nerves of the diabetic mice in this age range with those of unafflicted littermates with particular emphasis on the study of Schwann cells.

Diabetic mice which exhibited ataxic symptoms and hind limb performance deficits in a rotating-wheel test and unaffected littermates were sacrificed by per cardium perfusion of saline followed by 3% glutaraldehyde in 0.1M cacodylate buffer pH 7.3.
Scanning Electron Microscope Study of Bacteria on Mineral Surfaces
Authors: Berry V.K.
Published: June 2020

There are two strains of bacteria viz.Thiobacillus thiooxidansandThiobacillus ferrooxidanswidely mentioned to play an important role in the leaching process of low-grade ores. Another strain used in this study is a thermophile and is designatedCaldariella .These microorganisms are acidophilic chemosynthetic aerobic autotrophs and are capable of oxidizing many metal sulfides and elemental sulfur to sulfates and Fe2+to Fe3+. The necessity of physical contact or attachment by bacteria to mineral surfaces during oxidation reaction has not been fairly established so far. Temple and Koehler reported that during oxidation of marcasiteT. thiooxidanswere found concentrated on mineral surface. Schaeffer, et al. demonstrated that physical contact or attachment is essential for oxidation of sulfur.
Ultrastructural Changes Caused by Plant Cytokxnins on Dog Thyroid Follicular Cells “In Vitro”
Authors: Fernandez-Pol J. A.
Published: June 2020

Plant cytokinins are a group of growth promoting hormones with pronounced metabolic and regulatory effects not only on plants but also on microbial and animal cells (l). The effects of the N6-substituted derivatives of adenine, especially Zeatin (trans-6-(4-hydroxy-3-methylbut-2-enyl)- aminopurine) and Kinetin (6-furfurylaminopurine) on ultrastructure and on the in vitro response to Thyrotropin (TSH) or 8Br-cyclic AMP were studied in dog thyroid follicular cells.

Thyroid slices were incubated in the presence of Zeatin or Kinetin with and without TSH or 8Br-cyclic AMP, after 30min. prior incubation in Earle's solution. Effects on ultrastructure were observed after 30min. to 6hrs. of incubation. The thyroid slices after removal from incubation flasks were fixed immediately in 3%glutaraldehyde-formalin in 0.05M phosphate buffer. Specimens were then treated as described elsewhere (2). Observations were performed with a Siemens IA electron microscope.
Comparison of Scanning Transmission and Backscattered Electron Imaging in the Sem, Using Heavy Metal Stained Sections of Biological Tissue
Authors: DeNee Phillip B. , Frederickson Richard G.
Published: June 2020

The Transmission Electron Microscope (TEM) has been used extensively for the study of biological tissues in thin section (50-100 nm). For sectioned material greater than 100 nm, the Scanning Transmission Electron Microscope (STEM) and the High Voltage Electron Microscope (HVEM) have become the only alternatives for the study of these tissues at a resolution better than that obtained with the light microscope. Recently, it has been shown(1) that tissue stained with heavy metal can be studied in the Scanning Electron Microscope (SEM) by Backscattered Electron (BSE) imaging to give results similar to those obtained with the TEM. Because BSE imaging is a method complementary to STEM, it seemed worthwhile to compare the two techniques using the same specimens and beam conditions.

Direct observation of the total specimen is possible with BSE imaging without interference by grid bars. Therefore, an improved perspective of tissue-totissue structural relationships can be obtained at a resolution significantly better than that of the light microscope.
Darkfield Microscopy of Unstained Specimens at High Beam Dosages
Authors: Pullman J. M. , Crewe A. V.
Published: June 2020

We are currently studying unstained specimens with the STEM in the elastic darkfield mode in order to determine the smallest recognizable features in biological specimens exposed to beam dosages greater than 1 electron/ Å2. Although it has been shown that high resolution order in crystalline specimens disappears at such high doses, it is still necessary to take high-dose micrographs of non-crystalline specimens, particularly those labeled with heavy atoms, in order to obtain an adequate signal-to-noise ratio. High resolution micrographs of small protein molecules claiming structure at the 5 Å level have been published. Here we are concerned with obtaining a reliable comparison with stained specimens as visualized by conventional microscopy.
Electron Diffraction from Purified Wistar Rat Hemoglobin
Authors: Dobbs B. C. , Parsons D. F. , Garrick L. M.
Published: June 2020

Blood was obtained from the orbital sinus of adult Wistar rats, each rat yielding about 4ml of blood. The blood was collected in 3.8% sodium citrate, which served as an anticoagulant solution, washed four times in 0.9% NaCl-15mM Tris, then lysed by the addition of four volumes of 5mM Tris-HCl at pH 8.6. Centrifugation of 60,000g for one hour removed solid contaminants. The separation of the six different hemoglobins was accomplished by DEAE-Cellulose Chromatography. It was found that the six major hemoglobins which were designated 1 through 6, were approximately 7, 13, 20, 2, 45 and 13 percent of the total hemoglobin, respectively. Hemoglobin 5 was chosen for study because it was the most abundant.
A New Technique for the Light and Electron Microscopic Study of Individual Cerebro-Spinal Fluid Cells in a Mona Plane Layer
Authors: Dell L.A.
Published: June 2020

A new method has been developed which readily offers the microscopist a possibility for both light and electron microscopic study of selected cells from the cerebrospinal fluid. Previous attempts to examine these cells in the spinal fluid at the ultrastructural level were based on modifications of cell pellet techniques developed for peripheral blood. These earlier methods were limited in application by the number of cells in spinal fluid required to obtain a sufficient size pellet and by the lack of an easy method of cellular identification between the light and electron microscopic level. The newly developed method routinely employs microscope slides coated with Siliclad and tungsten oxide for duplicate cytocentrifuge preparations of diagnostic spinal fluid specimens. Work done by Kushida and Suzuki provided a basis for our use of the metal oxide.
A Weak-Beam Dark-Field Study of Stacking Faults in a Co-Cr-Mo-C Alloy
Authors: Hall Ernest L.
Published: June 2020

In a previous investigation (1) of the mechanisms of strengthening in a Co-28 wt% Cr-6 wt% Mo-0.29 wt% C alloy (H.S. 21), it was observed that the fee regions of this alloy were generally heavily faulted, and the density of stacking faults was seen to be dependent upon the time and temperature of the aging treatment after solutionizing. In the present study, weak-beam darkfield transmission electron microscopy was used to examine the interaction of stacking faults on intersecting {111} planes. The alloy was solutionized at 1230°C for 4 hours, quenched in water, and aged at 650°C for 8 hours in order to produce a suitable density of faults. Figure 1 shows a bright-field (BF), weak-beam dark-field (WB DF) pair of micrographs illustrating both the successful and unsuccessful intersection of faults which exist in different ﹛111﹜ planes.
Application of Transmission Scanning Electron Diffraction to Alloy Phase Transformations
Authors: Carpenter R. W.
Published: June 2020

The benefits to be gained by using the transmission scanning electron diffraction method in studies of alloy phase transformations depend on matching the special capabilities of the method with the particular diffraction phenomena associated with phase transformations. The transmission scanning method, sometimes termed the Grigson method, was originally developed for use on electron diffractometers. The essential features are a set of scanning coils placed around the scattered beam, and electron detector system for intensity measurement. More recently the use of the transmission scanning electron diffraction (TSED) method in modified transmission microscopes has been discussed. To use the method a set of scanning coils are positioned below the specimen, in the region of the intermediate or projector lens, for the purpose of scanning the diffraction pattern across a fixed aperatured detector, usually located below the final viewing screen.