bluuebunny/crossref_metadata_2025_split huggingface dataset:
Convenient multi-channel averaging for electron energy loss spectroscopy in the STEM
Authors: Batson P.E. , Chapman J.N. , Craven A.J. , Ferrier R.P. 
Published: June 2020

Electron energy loss spectroscopy (EELS) of electrons which have produced excitation of atomic electron core states promises to provide a powerful microanalytical tool. To assess fully the range of applications of the technique and its ultimate sensitivity in any given circumstance,accurate cross-sections differential in energy and scattering angle are required for both the characteristic energy loss electrons and for those loss electrons which contribute a background. In addition there is the possibility of gaining additional information on the nature of the specimen from the fine structure at the energy loss edge (Isaacson and Johnson 1975) and from the extended fine structure (EXELFS) beyond the edge (Colliex et al 1976), although neither of these phenomena are as yet well understood.We are currently investigating a number of aspects of EELS using a Vacuum Generators HB5 FEGSTEM at the Cavendish Laboratory, Cambridge. This is fitted with a magnetic spectrometer with air cored magnetic deflection at the magnet exit which can provide rapid energy scans without hysteresis.
In-situ observation of reversible twinning in U3Si
Authors: Kimmel G. , Admon U. , Zangvil A. 
Published: June 2020

The intermetallic compound U3Si has the cubic δ' structure between 765-900°C, and the tetragonal δ structure at lower temperatures. The δ' → δ transition always results in a twinned martensitic structure. Double shear causes the appearance of bands and sub-bands (1).Plastic deformation of martensitic U3Si is accompanied by detwinning, since only one of the twins is usually favorable from the point of view of the external stress. This was confirmed by optical metallography as well as by texture analysis (2).The present work describes a memory effect observed during a study of plastically deformed (⩽2%) martensitic U3Si.TEM specimens were prepared from lateral sections of standard tensile test samples. The principal stress direction was thus perpendicular to the foil.Fig. 1 shows the twinned structure of the martensite before deformation.Primary and secondary twins can be seen. The twinning systems are {101}<101> in FCT coordinates ({112}<111> in BCT coordinates). This was inferred from trace analyses.
H.V.E.M. observation of the nucleation of martensite in stainless steel
Authors: Brooks J.W. , Loretto M.H. , Smallman R.E. 
Published: June 2020

INTRODUCTIONThe mechanisms involved in the formation of martensite nucleii are still uncertain despite extensive investigations. Earlier work (e.g. Kelly and Nutting, 1961; Mangonon and Thomas, 1970; Fujita and Ueda, 1972) had suggested that stacking faults are important in the formation of ε martensite. Mechanisms have been proposed to account for the fact that α martensite can be formed at the intersection of faulted Regions (Bogers and Burgers, 1964) and for the formation of ε martensite from 1/6<112> partials ( Mahajan et al. 1977).In an attempt to remove the uncertainties we have observed directly the formation of ε and α martensites in stainless steels both during in situ deformation and during cooling.EXPERIMENTALHigh purity low carbon stainless steel of various compositions which transform to a martensite and ε martensite (with c/a less than ideal), produced by induction melting under argon, were rolled down into tfiin sheets suitable for preparing electron microscope specimens. These were then annealed to reduce the dislocation density.
TEM -analysis of the BeO-dispersion in high purity Be-ingots
Authors: Migge Hans 
Published: June 2020

Inclusions of BeO are of tremendous importance on the mechanical properties of Beryllium [1,2]. The BeO particle sizes of different hot pressed materials are in the range between 400 Å and 10 μm for BeO contents between 0.5 and 3.6%[3]. However, there is no investigation about the BeO dispersion in high purity (<200 ppm BeO) ingots. Information on this subject should be derived from the diffuse Debye rings of BeO, which as yet are thought to come from the very thin oxide scale on the Be-surface [3].0.1 mm foils of Berylco IF—1 from KBI with BeO < 200 ppm were analyzed at 100 kV in the as received condition or after annealing for 1 hour at 900°C in ultrahigh vacuum. With the electron beam parallel to [00.1], [11.1], [02.1], [12.1], [03.1], [12.2] (using different grains) always four diffuse BeO rings of the type {10.0}, {10.1}, {11.0}and the unresolved {20.0}/{11.2} appear in the SAD-pattern.
Electron microscopy observations of high temperature phase transitions in incongruent subliming materials
Authors: Schiffman R.A. , Mitchell M.J. 
Published: June 2020

Scanning and transmission electron microscopy investigations led to a new method of studying binary phase systems by observing the properties of samples whose composition or temperature is changing, either independently or simultaneously. The research produced a complementary method of describing complex temperature-composition diagrams. The nickel-sulfur system was chosen since it has been thoroughly investigated by other methods. The thermodynamics of binary metal systems have been described by Lundqvist, Rosenqvist and Kullerud and Yung using x-ray diffraction and thermal analysis. These methods began by preparing, at room temperature, the metal-sulfide composition desired. The temperature was then raised so that a constant composition line could be studied. As the temperature was changed, horizontal phase boundaries could be well defined. It is difficult, however, to use these methods to define vertical phase boundaries.Nagamori and Ingraham; Meyer, and Rau used weight loss measurements in a gas equlibrium to study limited parts of the nickel-sulfur system.
The direct visualization of macromolecular complexes in redundant cytomembrane systems with particular reference to peripheral nerve myelin
Authors: Pease Daniel C. 
Published: June 2020

A combination of little used preparative techniques permits the visualization of macromolecular complexes in peripheral nerve myelin. They can be employed effectively as well for similar particulate recognition in at least some other redundant cytomembrane systems, i.e. retinal disc membranes. The cores of the globular structures are thought to be the integral proteins of the membrane system, in glutaraldehyde-fixed myelin probably associated with phospholipid annuli.Fixation is limited largely to aldehydes, with osmium tetroxide being particularly contraindicated. Cadmium ions, which form water-insoluable salts with lecithins, seem to offer some advantages when included with a glutaraldehyde fixation. Tannic acid as a secondary fixative has proven necessary when embedments are to be avoided.
Toward the biochemistry of individual molecules
Authors: Wall J. S. , Hainfeld J. F. 
Published: June 2020

One goal of the Brookhaven STEM group is to enhance the capabilities of the electron microscope as a biochemical tool, while attempting to open up a new field: the Biochemistry of Individual Molecules. Three aspects of molecular biology seem particularly tractable with the STEM (Scanning Transmission Electron Microscope):Size, shape and molecular weightActive sites: location and environmentInteractions in complex systemsAll these areas have been explored to some extent by conventional microscopy, but definitive conclusions are elusive because of low contrast and radiation damage which usually require staining or shadowing to “see” anything. Periodic features may be rendered faithfully, but detailed interpretation falls prey to arguments about positive vs. negative staining, decoration vs. shadowing, flattening, shrinkage, and other such phenomenon.
Annulate lamellae in the Sertoli cells of guinea pig testis after unilateral torsion of the spermatic cord
Authors: Chakraborty J. , Sinha Hikim A. P. , Jhunjhunwala J. S. 
Published: June 2020

Although the presence of annulate lamellae was noted in many cell types, including the rat spermatogenic cells, this structure was never reported in the Sertoli cells of any rodent species. The present report is based on a part of our project on the effect of torsion of the spermatic cord to the contralateral testis. This paper describes for the first time, the fine structural details of the annulate lamellae in the Sertoli cells of damaged testis from guinea pigs.One side of the spermatic cord of each of six Hartly strain adult guinea pigs was surgically twisted (540°) under pentobarbital anesthesia (1). Four months after induction of torsion, animals were sacrificed, testes were excised and processed for the light and electron microscopic investigations. In the damaged testis, the majority of seminiferous tubule contained a layer of Sertoli cells with occasional spermatogonia (Fig. 1). Nuclei of these Sertoli cells were highly pleomorphic and contained small chromatinic clumps adjacent to the inner aspect of the nuclear envelope (Fig. 2).
The effect of bromocriptine on mammary-gland ultrastructure of hyperprolactinemic rats
Authors: Murray I.C. 
Published: June 2020

In women, hyperprolactinemia is often due to a prolactin (PRL)-secreting adenoma or PRL cell hyperplasia. RRL excess stimulates the mammary glands and causes proliferation of the alveolar epithelium. Bromocriptine, a dopamine agonist, inhibits PRL secretion and is given to women to treat nonpuerperal galactorrhea. Old female rats have been reported to have PRL cell hyperplasia or adenoma leading to PRL hypersecretion and breast stimulation. Herein, we describe the effect of bromocriptine and consequently the reduction in serum PRL levels on the ultrastructure of rat mammary glands.Female Long-Evans rats, 23 months of age, were divided into control and bromocriptine-treated groups. The control animals were injected subcutaneously once daily with a 10% ethanol vehicle and were later divided into a normoprolactinemic control group with serum PRL levels under 30 ng/ml and a hyperprolactinemic control group with serum PRL levels above 30 ng/ml.
Effect of piperacillin on morphology and viability of gram-negative bacteria
Authors: Liss R. H. 
Published: June 2020

Piperacillip (PIP) is b-[D(-)-α-(4-ethy1-2,3-dioxo-l-piperzinylcar-bonylamino)-α-phenylacetamido]-penicillanate. The broad spectrum semisynthetic β-lactam antibiotic is believed to effect bactericidal activity through its affinity for penicillin-binding proteins (PBPs), enzymes on the bacterial cytoplasmic membrane that control elongation and septation during cell growth and division. The purpose of this study was to correlate penetration and binding of 14C-PIP in bacterial cells with drug-induced lethal changes assessed by microscopic, microbiologic and biochemical methods.The bacteria used were clinical isolates of Escherichia coli and Pseudomonas aeruginosa (Figure 1). Sensitivity to the drug was determined by serial tube dilution in Trypticase Soy Broth (BBL) at an inoculum of 104 organisms/ml; the minimum inhibitory concentration of piperacillin for both bacteria was 1 μg/ml. To assess drug binding to PBPs, the bacteria were incubated with 14C-PIP (5 μg/0.09 μCi/ml); controls, in drug-free medium.
Anionic molecular organization in isolated sarcolemma of human heart muscle
Authors: Lee Y.S. , Chang C.H. 
Published: June 2020

Numerous studies using ultrastructural cytochemistry techniques have been published which bring out and characterize the surface membrane of many cell types. However, few of these studies are concerned with the sarcolemma of heart muscle cells. In particular, no detailed study has been reported relating to cytochemical characterization of isolated sarcolemma from human heart muscle. Thus, the present report was designed to observe and characterize the sarcolemmal ultrastructure of human ventricular myocardium with particular emphasis on anionic molecular organization in the membrane surface by means of electron microscopic and cytochemical studies.The present study was carried out on human heart specimens. The infundibular muscles of right ventricle were obtained during open heart surgery for total correction of 10 patients with congenital heart disease (tetralogy of Fallot). The procedures used for the isolation of cardiac sarcolemma were principally based on the method as described by McNamara et al.
Quantitation of the intramembrane particle distribution in C3H/10T½ cells treated with TPA and retinyl acetate.
Authors: Fassel T. , Hui S.W. 
Published: June 2020

The mouse embryo fibroblast C3H/10T½ cells are used as a model system for the study of ultrastructural changes caused by tumor promoter and “anti-promoter” treatments. Noninitiated fibroblasts treated with tumor promoter undergo phenotypic transformation. On the other hand, the retinoid, retinyl acetate (RA), is effective in suppression of the malignant phenotype in the 10T½ cells (1). We report on the rapid freezing and freeze fracture electron microscopy study of the plasma membrane ultrastructures of noninitiated C3H/10T½ fibroblasts after treatments of retinyl acetate or a tumor promoter, 12-0-tetradecanoyl-phorbol-13-acetate (TPA).Rapid freezing of cells enables structure to be preserved without the use of cryoprotectants and chemical fixatives, which may alter membrane structural organization. For rapid freezing, 10T½ cells were grown as monolayers on glass specimen supports. The glass-copper specimen holder sandwiches were rapidly frozen by automatic plunging into liquid propane. Freeze fracture was carried out in a Polaron-Ultek ion pump apparatus with Cressington electron guns.
Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves
Authors: Edith Taylor S. , Echlin Patrick , McKoon May , Hayes Thomas L. 
Published: June 2020

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.
Electron microscopy investigation of sputtered and glow-discharge amorphous silicon-tin alloys
Authors: Jones K. M. , Williamson D. L. , Yacobi B. G. 
Published: June 2020

The alloying of amorphous silicon with tin for systematic modification of the optical band gap for multijunction thin film solar cell applications has recently attracted interest. This is a comparative study of the microstructural properties of both the RF sputtered and glow discharge a-Si:Sn thin films. Sputtered films were deposited at 20 mTorr and 4 mTorr dynamic pressures of Ar-10 vol.% H2. Glow discharge films were deposited using SiH4, H2 and Sn(CH3)4 gas mixtures. Details of both the sputtering and glow discharge deposition conditions have been recently published elsewhere.In this work, Sn precipitation was observed in all hydrogenated sputtered alloys. Figure 1 shows the increase of the density of precipitates as a function of Sn concentration. These micrographs also reveal a non-coalesced (cauliflower) microstructure in the matrix. Figure 2 shows edge on view SEM micrographs of one of the sputtered films, which shows Sn precipitates originating at the substrate and in the bulk of the growing film. In a device structure, this would lead to electrical shorting and prevent the application of this material to solar cells.
Defect Structure Analysis in Semiconductors by HREM and New Compatible Techniques
Authors: Spence J.C.H. 
Published: June 2020

The determination of atomic co-ordinates from HREM images has greatly improved our understanding of semiconductor defects, but chemical and electronic structure information are also needed. Thus suitable HREM compatible techniques must be developed and this article reviews some of these.The intimate relationship between resolution and noise has been exploited for many years in biological HREM. Since the centre of a very broad gaussion peak can be found with an accuracy which depends mainly on noise, heavy atom positions in inorganic crystals can be determined from HREM images with an accuracy of ±0.1Å (well beyond the information and point resolution limits of an HREM image) by the addition of similar unit cell images. This method makes extensive use of a-priori information (that there is only one atomic column rather than an unresolved pair, other atom co-ordinates, symmetry) and fails for isolated defects, but may be useful for semiconductor interfaces and surfaces.
Detection of subsurface cracks and delaminations in polymeric materials by electron thermoelastic acoustic microscopy
Authors: Begnoche Bruce C. , Holstein William L. 
Published: June 2020

Electron Thermoelastic Acoustic Microscopy (ETEAM), also termed Electron Acoustic Microscopy and Thermal Wave Microscopy, detects subsurface cracks, delaminations, and voids at depths up to at least 100 µm, as first reported by Cargill, The technique has previously been applied only to beam-insensitive materials, since high beam currents of about 1 µamp (1000 times greater than for routine SEM) are required to obtain adequate signal intensity. We present here a procedure for extending the technique to beam-sensitive polymeric materials.In the ETEAM technique, a periodic electron beam (frequency V = 10 kHz-10 MHz) generates an acoustic wave, leading to a periodic force on a transducer attached to the specimen. The ETEAM image is derived from the transducer voltage output as the electron beam is scanned over the sample in an SEM. The inability of an acoustic wave to travel through a delamination results in it being transmitted around the delamination as a transverse shear wave (Fig. 1).
Electron microscopy of selected manganese oxide concretions
Authors: Chen Cy-Chain 
Published: June 2020

Four manganese oxide samples representing different oxidation-reduction environments were examined by transmission electron microscopy (TEM) to observe the morphology and by electron diffraction (ED) to identify the mineral species. Samples selected were:Manganese oxide concretion in Nada subsoil.Manganese oxide concretion in Crockett subsoil.Concretion formed in topsoil at a trickle irrigation water outlet.Weathering product of siderite (FeCO3) as a black coating on the exterior surface of the rock.Fine clay fractions (<0.2 μm) were obtained by ultrasonication followed by repreated washing and centrifugation. Dilute suspensions were deposited on Formvar coated grids. All observations were made on a Zeiss 10C TEM at 60kV. Magnesium oxide and synthetic hematite (α-Fe2O3) were used as ED standards. Supplementary data were obtained by x-ray diffraction (XRD).
Crystal structure images of large gold clusters and growing crystals by HRTEM
Authors: Wallenberg L.R. , Bovin J.-O. , Schmid G. 
Published: June 2020

Metallic clusters are interesting from various points of view, e.g. as a mean of spreading expensive catalysts on a support, or following heterogeneous and homogeneous catalytic events. It is also possible to study nucleation and growth mechanisms for crystals with the cluster as known starting point.Gold-clusters containing 55 atoms were manufactured by reducing (C6H5)3PAuCl with B2H6 in benzene. The chemical composition was found to be Au9.2[P(C6H5)3]2Cl. Molecular-weight determination by means of an ultracentrifuge gave the formula Au55[P(C6H5)3]Cl6 A model was proposed from Mössbauer spectra by Schmid et al. with cubic close-packing of the 55 gold atoms in a cubeoctahedron as shown in Fig 1. The cluster is almost completely isolated from the surroundings by the twelve triphenylphosphane groups situated in each corner, and the chlorine atoms on the centre of the 3x3 square surfaces. This gives four groups of gold atoms, depending on the different types of surrounding.
Overview of industrial machine vision
Authors: Mandeville Jon R. 
Published: June 2020

One hardly needs to emphasize the importance of visual sensing and interpretation in our everyday lives and the severe limitations and handicaps imposed on the blind. The importance of human vision has motivated an intense interest in and significant research on artificial vision systems over the last 20 years. The relatively new, fast growing discipline of “machine (or computer) vision” is an outgrowth of this research.Machine vision is computation on images to produce useful, meaningful descriptions of a visual environment. A machine vision system may be used either as a symbiotic enhancement to human vision or as the perceptual component of an autonomous, goal-driven computational system capable of cognitive processing.
Localization of adenylation site on glutamine synthetase ofE. coliby immunoelectron microscopy and image averaging
Authors: Wagenknecht T. , Bronstein G. , Frank J. , Frink R. , Eisenberg D. , Glitz D. 
Published: June 2020

The glutamine synthetase (GS) from E. coli is a donut-shaped molecule comprising 12 identical subunits arranged in two opposing hexameric layers (dihedral D6 symmetry). In one mode of regulating enzymatic activity, each of the subunits is subject to adenylation at a specific tyrosine residue. A previous study used the technique of immunoelectron microscopy to map the position of adenylation on the surface of the molecule. We describe here a refinement of the analysis be means of computerized single particle averaging methods.Electron micrographs were digitized with a .78 nm sampling distance and images of GS in the six-fold orientation were selected and brought into mutual alignment by correlation methods. The images were divided into two classes depending on whether or not an antibody was visible at the periphery of the molecule. Selected examples of control and antibody-labeled molecules are shown in Fig. la,b respectively.
Ultrastructural study of a granular cell tumor from forearm
Authors: Sun C.N. , Shaefer R. 
Published: June 2020

Granular cell tumors are frequently reported in different body locations. Some authors believed it to be a neoplasm derived from skeletal muscle and others propose the origin of these lesions are from fibroblasts, histocytes, mesenchymal cell, neuron or Schwann cells. So far the tumor cells origin is still controversial. The purpose of this report is to present a case showing the cellular fine structures and to propose a possible origin of the tumor cells.A tumor mass (5 x 3 cm) from the left forearm of a 49 year old white male was removed, cut into small pieces (about 1 mm3), immediately fixed in 4 percent glutaraldehyde in phosphate buffer for 2 hours, and then post fixed in 1 percent buffered osmium tetroxide for 1 hour. After dehydration, tissues were embedded in Epon 812.
Ultrastructure of the soil fungus, Geomyces pannorus
Authors: Traquair J. A. , Kokko E. G. 
Published: June 2020

With the advent of improved dehydration techniques, scanning electron microscopy has become routine in anatomical studies of fungi. Fine structure of hyphae and spore surfaces has been illustrated for many hyphomycetes, and yet, the ultrastructure of the ubiquitous soil fungus, Geomyces pannorus (Link) Sigler & Carmichael has been neglected. This presentation shows that scanning and transmission electron microscopical data must be correlated in resolving septal structure and conidial release in G. pannorus.Although it is reported to be cellulolytic but not keratinolytic, G. pannorus is found on human skin, animals, birds, mushrooms, dung, roots, and frozen meat in addition to various organic soils. In fact, it readily adapts to growth at low temperatures.