bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantification of ultrastructural damage in human skeletal muscle
Authors: Manfredi T. G. , Ding W. , Evans W. J. , Fielding R. A. , Cannon J. G. , Lee H. Y. , Verdon S. L. 
Published: June 2020

Qualitative microscopic analysis of muscle architecture provides information about cellular markers of muscle fiber disruption in myopathic, aging, and experimentally damaged muscle. However, this approach does not provide sensitive information regarding the extent of muscle damage and has serious limitations when research protocols address tissue remodeling. The purpose of this study was to quantitatively assess the extent of muscle damage in young and older adults before and after exercise-induced damage. The older adults in this study had lower aerobic capacities and muscle mass than their younger counterparts, suggesting greater vulnerability toward muscle damage produced by physiologic stress.Five young males, ages 20 to 29 years and five older males, age 60 to 75 years had percutaneous needle biopsies taken from the vastis lateralis muscle before and after (N=9) exercise consisting of reverse cycling or downhill treadmill running at a prescribed physiologic effort. Muscle samples were prefixed in 3.0% gluteraldehyde in cacodylate buffer and post-fixed in VL OSO4. This was followed by routine procedures for TEM.
Grass leaf stomata preparation techniques for scanning electron microscopy
Authors: Hardy Joyce Phillips , Gardner John S. 
Published: June 2020

Studies on gramineous stomatal characteristics, such as stomatal density and aperture size, relate these traits to ecological concerns, e.g. drought tolerance and production. Techniques for studying stomata have been utilized in the past using light microscopy. In a comparative study of stomatal apertures, it is imperative that guard cell closure not occur and die cells retain as closely as possible their natural state at the time of collection. Two species utilized in seeding roadsides and pastures, Dactylis glomerata L. and Elymus canadensis L., were processed with four different techniques for the scanning electron microscope. Abaxial and adaxial surfaces, respectively, were examined.Leaf tissue was harvested from clonal greenhouse-grown plants and separated into four groups. One was air dried under ambient conditions. The second group was placed into a standard fixative. Following fixation, the samples were dehydrated through a standard series of ethanol and critical point dried. The third group was prepared the same as group 2, except the leaves were transferred to tetramethylsilane for two ten minute exchanges following ethanol dehydration.
Measurements of DNA distribution changes in live cells
Authors: Palcic B. , Spadinger I. 
Published: June 2020

It has long been recognized by pathologists that many diseases can be diagnosed by examination of stained cell preparations. Particularly important information is found in the cell nucleus. For example, in the diagnosis of cancerous and pre-cancerous states in cervical cells, nuclear size, shape, and distribution of DNA have been used to classify the cells. Many other examples can be found in the examination and diagnosis of malignant diseases and other abnormalities.In experimental cell biology, one also finds numerous examples where critical information regarding cell status is found in the nuclear DNA. One of the most commonly used assays is that of determining DNA amount and/or degree of condensation in order to define cell cycle position. Effects of exposure to damaging agents such as ionizing radiation or toxic chemicals are also frequently assessed through examination of changes in the cell nucleus. Endpoints such as chromosome aberrations (breaks, translocations, etc.) and formation of micronuclei are commonly used in such assays.
Video microscopic studies of membrane dynamics
Authors: Jacobson Ken , Lee Greta , Lee Juliet 
Published: June 2020

The application of several imaging technologies and photobleaching to problems in membrane dynamics will be presented. These techniques emphasize different aspects of the measurement of translational transport: (1) tracing the trajectories of individual molecules undergoing a two dimensional random walk, and (2) investigating bulk changes in the distribution of membrane components in the plane of the membrane in single, locomoting cells.Nanovid microscopy, which uses 30-40 nm colloidal gold probes combined with video-enhanced contrast, allows investigation of random and directed movements of individual molecules in artificial membranes or in the plasma membrane of living cells. The movements of lipid molecules were followed in a supported, planar bilayer containing fluorescein-phosphatidylethanolamine (Fl-PE) labelled with 30 ran gold anti-fluorescein (anti-Fl) to validate the technique in a model system. The membrane-bound gold particles moved in random patterns which were indistinguishable from those produced by computer simulations of two dimensional random motion.
A new 1.4 nm gold-Fab probe
Authors: Hainfeld James F. , Fumya Frederic R. , Powell Richard D. 
Published: June 2020

A major advance in high resolution EM immunoprobes has recently been achieved: The smallest gold particles easily seen directly in the TEM have been coupled to Fab fragments thus making them the smallest gold-antibody probe commercially available.The gold particle, NanogoldTM, is 1.4 nm in diameter with a very controlled size range, ± 10% (Fig. 1). This is in sharp contrast to other small gold preparations, such as Auroprobe One (Janssen Life Sciences) which actually ranges from 1-3 nm.The Fab conjugate (Fig. 2) has close to one gold particle per Fab fragment. This again is different from other gold-IgG probes that have 0.2-10 gold particles per IgG. Another difference is that the Nanogold-Fab conjugates are separate molecules in solution rather than the often extensive aggregation of other colloidal gold-IgG preparations. The problems of ratio of gold particles to antibody and aggregation in conventional colloidal conjugates were shown to be controllable by careful trial and error testing.
Artifacts caused by dehydration and epoxy embedding in TEM
Authors: Mollenhauer Hilton H. 
Published: June 2020

Various means have been devised to preserve biological specimens for electron microscopy, the most common being chemical fixation followed by dehydration and resin impregnation. It is intuitive, and has been amply demonstrated, that these manipulations lead to aberrations of many tissue elements. This report deals with three parts of this problem: specimen dehydration, epoxy embedding resins, and electron beam-specimen interactions. However, because of limited space, only a few points can be summarized.Dehydration: Tissue damage, or at least some molecular transitions within the tissue, must occur during passage of a cell or tissue to a nonaqueous state. Most obvious, perhaps, is a loss of lipid, both that which is in the form of storage vesicles and that associated with tissue elements, particularly membranes. Loss of water during dehydration may also lead to tissue shrinkage of 5-70% (volume change) depending on the tissue and dehydrating agent.
Imaging intracellular membrane traffic and organelle dynamics using confocal microscopy
Authors: Cooper M. S. 
Published: June 2020

Movements of exocytic and endocytic vesicles within cells are controlled in part by active transport along microtubules. The forces generated by microtubule-based transport are also known to strongly influence the distribution and shapes of membranous organelles, such as mitochondria and the endoplasmic reticulum. The ability to observe such dynamic interactions between cytoskeletal elements and fluorescently-labelled intracellular membranes in living cells has been improved recently by the advent of scanning laser confocal microscopy. Here we describe the use of this technique to study activities of the Golgi apparatus in living cells.Vesicular traffic, diffusive transport and morphological dynamics within the Golgi apparatus of cultured rat hippocampal astrocytes were imaged with a Bio-Rad MRC-500 scanning laser confocal microscope. Golgi elements were labelled with NBD-ceramide, a molecule which serves as a vital stain for the trans-most cisternae of Golgi stacks. Single scans of the specimen, obtained with the laser microscope's slow scan rate (4 sec/image), were stored sequentially on an optical memory disk recorder.
Prospects for convergent beam electron diffraction with a 200kV cold field-emission transmission electron microscope
Authors: Steeds J W , Vincent R 
Published: June 2020

We review the analytical powers which will become more widely available as medium voltage (200-300kV) TEMs with facilities for CBED on a nanometre scale come onto the market. Of course, high performance cold field emission STEMs have now been in operation for about twenty years, but it is only in relatively few laboratories that special modification has permitted the performance of CBED experiments. Most notable amongst these pioneering projects is the work in Arizona by Cowley and Spence and, more recently, that in Cambridge by Rodenburg and McMullan.There are a large number of potential advantages of a high intensity, small diameter, focussed probe. We discuss first the advantages for probes larger than the projected unit cell of the crystal under investigation. In this situation we are able to perform CBED on local regions of good crystallinity. Zone axis patterns often contain information which is very sensitive to thickness changes as small as 5nm. In conventional CBED, with a lOnm source, it is very likely that the information will be degraded by thickness averaging within the illuminated area.
Combining slow-scan CCD images to extend image size and dynamic range
Authors: Fan G.Y. , Gubbens A.J. , Krivanek O.L. , Leber M.L. , Mooney P.E. 
Published: June 2020

A slow-scan CCD (SSC) camera attached to an electron microscope can record images with 4096 gray levels, nonlinearity less than ±1 %, and a detective quantum efficiency (DQE) greater than 0.5 even with just one primary electron per pixel. Moreover, the images are read out by a computer and are therefore available for further processing as soon as they are acquired. SSC cameras therefore seem destined to replace photographic film as the primary recording medium used in electron microscopy as completely as they have in top-level optical astronomy, where film is now mostly of historical interest.However, the SSCs have two disadvantages compared to photographic film: 1) Fewer number of pixels and 2) the “spill” problem. Currently, SSCs are available for electron microscopists with a sensor array of up to 1024x1024 pixels. (2048x2048 CCD sensors have been developed but their price is high and performance, in terms of pixel defects, is low.) By comparison, a micrograph can record about 10,000x10,000 pixels. And, in order to maximize sensitivity, SSCs do not incorporate anti-blooming wells. As a result, a saturated pixel caused by, for example, a Bragg spot, will “spill” into neighboring pixels.
Decomposition of Ni-23 at.% Si and formation of Ni3Si
Authors: Baker I. , Schulson E.M. 
Published: June 2020

The purpose of the paper is to outline the formation of Ni3Si from Ni-23 (at. %) Si. The Ni-23Si was annealed at 1130°C for 24 h and quenched, after which it consisted of ∼10μm particles in an otherwise single phase matrix. To produce the peritectoid transformation to Ni3Si, samples were annealed at 725°C.Thin foils of Ni-23Si were prepared by electropolishing 250μm thick discs with 13% hydrochloric acid in methanol in a Struers Tenupol at -40°C, 40V (200 mA) and a medium flow rate. After perforation, the thin foils were rinsed in ethanol before washing in hydrofluoric acid for 30-40s. The foils were examined in a JEOL 2000FX TEM, furnished with a Tracer Northern TN5500 EDS system.
Quantitative mineral compositional analysis using digital x-ray images
Authors: Liang Long C. 
Published: June 2020

Digital x-ray imaging (DXI) has been utilized to display spatial elemental distribution and to conduct quantitative elemental compositional mapping on various samples. The quantitative elemental compositional mapping technique, however, requires the use of an advanced image analysis and computer system to display elemental concentration maps. In this study, a simplified DXI technique is used to achieve two goals: (1) display elemental distribution, and (2) conduct quantitative mineral compositional analysis using stored digital x-ray maps. The analytical procedure of this technique can be easily implemented to similar instruments in any laboratory.Quantitative analysis with the simplified DXI technique is performed using background-corrected elemental pixel intensities instead of using net x-ray counts as in a conventional electron microprobe analysis. In this study, digital x-ray mapping has been conducted using a JEOL 733 electron microprobe automated with a Tracor Northern (TN) 5500/5600 system. A TN image analysis program, IPP, was used to acquire all digital x-ray maps at an accelerating voltage of 15 kV and a beam current of 15 nA.
TEM study of thin iron oxide films deposited by pulsed-laser ablation
Authors: Anderson Ian M. , Grant Norton M. , Barry Carter C. 
Published: June 2020

Iron-oxide-based compounds are of technological interest because of their unique magnetic properties. Thin films of these compounds are especially suited to applications such as magnetic recording devices. The binary Fe-O system provides a model for the study of iron-oxide-based compounds, since the multiple valence of the Fe cations permits the formation of phases having a variety of crystal structures. These structures include rock salt (wüstite, Fe1-δO), two spinels (magnetite, Fe3O4 and maghemite, γ-Fe2O3), and corundum (hematite, α-Fe2O3). The former three phases have cubic-close-packed oxygen sublattices, while the latter has a hexagonal-close-packed oxygen sublattice. The γ-Fe2O3 phase is a metastable, cation-deficient spinel, generally formed by careful low-temperature oxidation of the magnetite phase.Thin iron oxide films have been deposited by pulsed-laser ablation onto (001)-oriented MgO single-crystal substrates. The microstructure and epitaxy of these films have been studied using transmission electron microscopy (TEM) and selected-area diffraction (SAD).
Luminescence from individual dislocations in II-VI and III-V semiconductors
Authors: Steeds J W 
Published: June 2020

There is a wide range of experimental results related to dislocations in diamond, group IV, II-VI, III-V semiconducting compounds, but few of these come from isolated, well-characterized individual dislocations. We are here concerned with only those results obtained in a transmission electron microscope so that the dislocations responsible were individually imaged. The luminescence properties of the dislocations were studied by cathodoluminescence performed at low temperatures (~30K) achieved by liquid helium cooling. Both spectra and monochromatic cathodoluminescence images have been obtained, in some cases as a function of temperature.There are two aspects of this work. One is mainly of technological significance. By understanding the luminescence properties of dislocations in epitaxial structures, future non-destructive evaluation will be enhanced. The second aim is to arrive at a good detailed understanding of the basic physics associated with carrier recombination near dislocations as revealed by local luminescence properties.
Island Growth during the Crystallization of Amorphous Ge48Te52 Films
Authors: Libera M. , Chen M. 
Published: June 2020

Microstructural TEM studies have been combined with temperature-dependent measurements of laser reflection and transmission to study crystallization in amorphous films of near-stoichiometric germanium telluride. The transformation proceeds by rapid growth of crystalline islands through the film thickness followed by two-dimensional growth in the film plane. Isothermal studies find an Avrami exponent of 4.5 suggesting a non-linear crystal growth rate.75nm of Ge48Te52 was deposited by co-evaporation from separate Knudsen cells onto Si, carbon-coated mica, and glass substrates. Compositions were determined by x-ray fluorescence from films deposited on silicon.
Microstructural Evaluation of Silicon Carbide Whisker Reinforced Alumina Fabricated with Carbon-Coated Whiskers
Authors: Alexander K. B. , Becher P. F. 
Published: June 2020

The presence of interfacial films at the whisker-matrix interface can significantly influence the fracture toughness of ceramic composites. The film may alter the interface debonding process though changes in either the interfacial fracture energy or the residual stress at the interface. In addition, the films may affect the whisker pullout process through the frictional sliding coefficients or the extent of mechanical interlocking of the interface due to the whisker surface topography.Composites containing ACMC silicon carbide whiskers (SiCw) which had been coated with 5-10 nm of carbon and Tokai whiskers coated with 2 nm of carbon have been examined. High resolution electron microscopy (HREM) images of the interface were obtained with a JEOL 4000EX electron microscope. The whisker geometry used for HREM imaging is described in Reference 2. High spatial resolution (< 2-nm-diameter probe) parallel-collection electron energy loss spectroscopy (PEELS) measurements were obtained with a Philips EM400T/FEG microscope equipped with a Gatan Model 666 spectrometer.
Koehler illumination advantages for imaging in TEM
Authors: Probst W. , Bauer R. , Benner G. , Lehman J. L. 
Published: June 2020

The Koehler principle of correct illumination in the light microscope was described about 100 years ago by A. Koehler. It is used in most of todays upper class light microscopes in order to achieve optimal imaging conditiones. Basically, in light microscopy (LM) and electron microscopy (EM) the same optical principles are used in order to describe or design beam paths in the different types of instruments. Mainly due to technical reasons up to now it was, however, not possible to transfer all the advantageous optical experience from LM to EM. The EM 910 from Carl Zeiss is now the first TEM providing the benefits of Koehler illumination.The Koehler principle is the most favourable design of the illumination beam path of a microscope as an imaging beam path for the source. In the first step the light source (LM) or the electron beam crossover (TEM) is imaged into the front focal plane of the condenser lens (LM) or the objective-prefield lens (TEM), respectively.
Secondary-electron yield measurements of conducting polymers in the Scanning electron microscope
Authors: Susczynsky D. M. , Klavetter F. I. 
Published: June 2020

In recent years, research on conducting polymers has been motivated to a large extent by the prospect of developing low-cost, light-weight conducting polymeric materials for commercial use. Conducting polymers have potential uses as electrodes and/or electrolytes for rechargeable batteries, as power conductors andpowercable sheathing and as material for space photovoltaics and spacecraft-charging applications.The utilization of conducting polymers for spacecraft construction and instrumentation requires an understanding of how such materials respond to the spacecraft environment. Of particular importance is how and to what degree such a material will charge when exposed to the wide range of energetic fluxes of electrons and protons that characterize a typical satellite environment. For typical space plasma environments, the total charging current to a satellite is given by the net sum of the electron and proton particle currents from the ambient plasma to the satellite, the secondary-electron and backscatter-electron emission currents arising from ambient-particle impact, and the photoelectron emission current resulting from solar UV.
Structure of high-angle-tilt boundaries in YBa2Cu3-O7-x thin films
Authors: Shin D. H. , Silcox J. , Russek S. E. , Lathrop D. K. , Moeckly B. H. , Buhrman R. A. 
Published: June 2020

It has been known that high angle tilt grain boundaries in c-axis oriented YBa2Cu3O7-x thin films cause weak link behavior in the transport properties reducing Jc's by several orders of magnitude. These grain boundaries have been shown to be clean both structurally and chemically by high resolution imaging and microanalysis studies. Therefore the mechanism of weak link behavior in thin film YBa2Cu3O7-x is not yet understood.Recently it has been deduced from the behavior of weak link Jc under small magnetic fields that the high angle tilt boundaries are nonuniform, consisting of several regions of good contact, each about 5-10 % of the boundary length, with the rest of the boundary region being poor. This seems to suggest that the superconducting properties at the boundary may be sensitive to changes in structures of atomic scale, since typical grain boundaries are free of macroscopic (≥ 10 Å) defects all along the boundaries.
Electron diffraction contrast of fluxons
Authors: Qin L.C. , Marks L.D. 
Published: June 2020

Partial penetration of an applied external magnetic field occurs in type-II superconductors. The properties of magnetic fluxons are important in determining the critical current density of type-II superconductors as it is the mobility of the fluxon lattice that limits the high value of critical current density of superconductors. There have been various experimental techniques in use to study the fluxons, e.g. the decoration technique, neutron diffraction, electron holography and scanning tunneling microscopy.Noting that in the thin crystal case the magnetic fluxes have a tangential component which deflects incident electrons, we explore the possibility of using conventional electron diffraction contrast technique to observe the fluxons. This is accomplished by using the London model for the vortex in thin crystals and the classical electromagnetic theory based on Maxwell equations to construct the magnetic field of a fluxon.
TEM sample preparation with focused ion beams
Authors: Kirch S. J. , Anderson Ron , Klepeis Stanley J. 
Published: June 2020

The continuing reduction in the sizes of features of interest for integrated circuit failure analysis requires greater precision in transmission electron microscopy (TEM) sample preparation. With minimum feature sizes approaching 0.5 μm, the mere finding of such a feature at a polished edge, let alone preparing a TEM sample containing it becomes a formidable task. The required substantial thinning also increases the risk of loss of what may be a unique sample.We present in this paper a technique that allows localized thinning of cross-sectional TEM samples using a focused ion beam (FIB) machine. Standard preparation techniques are used to make a cross-sectional TEM sample that would otherwise be too thick to be very useful for TEM analysis. This sample is then placed in the FIB machine, which is used as a micromachining tool. No special surface preparation is necessary and the secondary electron signal generated by the ion beam provides an image that can be used to locate the feature of interest.
Precautions toward XTEM of Si3N4/SiO2
Authors: Ogbuji Linus U.J.T. 
Published: June 2020

Because of extreme differences between the mechanical properties of Si3N4, and SiO2 usual means of specimen preparation pose severe difficulties every step of the way in the XTEM of oxidized silicon nitride. Perhaps that explains the lack of TEM investigation of the report that the Si3N4/SiO2 interface is duplex. This paper highlights some of the problems encountered in that system, and the remedies employed.The problems begin with abrasive preparation. While lapping on wheelbonded diamond removes material uniformly, diamond paste polishing does not: the fine particles lodge in the boundary of interest and destroy the oxide. Next comes dimpling. Its load focuses at a point over/near the boundary and crushes the fragile oxide. Fig. 1 shows a dimple that was aborted at 10μm depth on a foil 90μm thick. Load was 10 gm. Though offset from the boundary, the dimpling still crushed adjoining oxide.