bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estrogen and progesterone receptors in carcinoma of the breast (A cytochemical, immunofluorescence and electron microscopic study)
Authors: Elliott Robert L. , Harrison Gregory O. , Coble-Landry Anne , Bullock-Ledford Lindsay , McRea Anne T. , Nutt Debbie 
Published: June 2020

Tissue from 105 patients with infiltrating ductal carcinoma of the breast was assayed for the estrogen and progesterone receptor by the cytochemical dextran coated charcoal technique and by immunofluorescence with a direct dual staining procedure with Fluorocep, and also examined electron microscopically.Tissue was fixed in Zambonis; post-fixed in 1% OsO4; embedded in a Med Cast Resin, and thin sections were cut on a ultramicrotone. They were stained with uranyl acetate and lead citrate and examined in a Hitachi H-600 electron microscope.
Reconstruction with noisy data
Authors: Barrett T. A. 
Published: June 2020

The problem of deducing the 3-D structure of an object given a limited number of 2-D projections (e.g., STEM micrographs) is well-known. It is an ill-posed problem in the sense that very many solutions exist that have the same 2-D projections. If the data are assumed to be noisy (most STEM images are very noisy), then the problem is still ill-posed: many solutions exist that yield the same least-square error from the data.Crewe et al. have shown that, remarkably, the constraint that many objects are essentially Boolean in nature (have constant density) means that their structure can be determined very well even with very few projections, if there is little noise.
A parallel-detection electron spectrometer using quadrupole lenses
Authors: Ahn Channing C. , Krivanek Ondrej L. 
Published: June 2020

Serial detection systems that are standardly employed in electron energy loss spectrometry (EELS) only examine one energy channel at a time and are therefore inherently inefficient. Parallel detection systems using either photodiode arrays or charge-coupled devices (CCDs) promise to remove this inefficiency. However, to completely replace the serial detection systems, they will need 1) a detective quantum efficiency (DQE) approaching 100%, 2) a dynamic range sufficient to cover the range of intensities encountered in the energy loss spectra (about 106), and 3) ability to operate without any loss in energy resolution.We have constructed and tested a parallel detection system which incorporates three quadrupole lenses placed after the magnetic sector prism of the Gatan 607 spectrometer, a single crystal YAG scintillator, and a fiber-optically coupled linear photodiode array. The quadrupoles magnify the small dispersion (1.8μm per eV at 100kV primary voltage) of the spectrum produced by the magnetic sector to as high as 1 mm per eV without producing any spectrum rotation and with small power requirements.
On parallel illumination conditions for ALCHEMI
Authors: Christenson K. K. , Eades J. A. 
Published: June 2020

ALCHEMI is a technique for locating atomic species within a crystal structure. It depends on the fact that, near low index planes or zone axes, the ratio of the x-ray signals from different sublattices vary as a function of the angle between the incident beam and the crystal structure.In order to see the changes in these ratios, it is necessary that the illumination be close to parallel in order to minimize the angular range of the measurement. In simple cases it is sufficient to make the convergence angle smaller than the operating Bragg angle. This requirement can often be met by the conditions of a focussed probe.
On the role of tin underlays for the prevention of thermal grooving in thin gold films
Authors: Kim Jin Young , Hummel R. E. , DeHoff R. T. 
Published: June 2020

Gold thin film metallizations in microelectronic circuits have a distinct advantage over those consisting of aluminum because they are less susceptible to electromigration. When electromigration is no longer the principal failure mechanism, other failure mechanisms caused by d.c. stressing might become important. In gold thin-film metallizations, grain boundary grooving is the principal failure mechanism.Previous studies have shown that grain boundary grooving in gold films can be prevented by an indium underlay between the substrate and gold. The beneficial effect of the In/Au composite film is mainly due to roughening of the surface of the gold films, redistribution of indium on the gold films and formation of In2O3 on the free surface and along the grain boundaries of the gold films during air annealing.
High-resolution characterization of zeolites
Authors: Gómez-Castillo R. , Angel-Vicente P. Del , Domínguez-Esquivel J. M. 
Published: June 2020

Structural variations such as microdefects, symmetry changes and crystalline intergrowths might influence the catalytic and chemisorptive properties of zeolites. Those variations occur at a very local scale, making it that traditional x-ray diffraction techniques are unsuitable to detect them. The alternative methods are high resolution electron microscopy and solid state- NMR.The HREM images obtained in the microscope are influenced by instabilites of the zeolite crystals, beam damage, electronoptical parameters and other dynamical interactions, which add each other to produce a rather complex picture. Thus, the correct interpretation of results requires the determination of pa rameters, i.e. defocus, resolution level, astigmatism, etc.; together with the calculation of images, i.e. through Multislice methods.
A comparison of hog and synthetic bristles
Authors: Barish Leo 
Published: June 2020

It is generally accepted that hog bristles hold paint and resist dripping better than synthetics. It would appear that these properties may be related to the wettability of the bristle surfaces by paint. As an analog, experiments were performed in which advancing and receding contact angles of drops of mineral oil were measured against bristle surfaces. Surprisingly, it was found that hog bristles produced higher contact angles indicating that wetting was actually less than that of synthetics.Major differences in the texture of the surfaces between both types of bristles were found which probably relate to paint holding ability. Whereas conventional synthetic bristles showed smooth, featureless surfaces, the hog bristles (Figure 1) exhibit a very rough, scaled structure. Such an intricate surface would be expected to present a greater area and entrap paint better than a smooth surface.
Observation of slip propagation across grain boundaries in Ni3Al
Authors: Baker I. , Schulson E.M. , Horton J.A. 
Published: June 2020

Recent modelling of the grain size dependence of the room-temperature yield strength of Ni3Al has invoked the concept of dislocation pile-ups. The idea is that the yield strength measured in the Liiders regime (i.e. the Liiders band propagation stress) represents not the stress to independently nucleate slip in each grain but the stress required to propagate slip through the material. This paper presents direct evidence of slip propagation from one grain to the next and thus validation of the use of a pile-up model for Ni3Al.Miniature tensile specimens (3 mm x 7 mm x0.2 mm), made from an extruded rod of fine-grained (∽10 μm) Ni3Al containing 0.35 at.% boron, were strained under tension whilst being observed in a Philips EM 430T operated at 300 KV. Details of the design and operation of the straining stage and of the specimen preparation techniques are given elsewhere.
Computer-assisted analysis of incomplete powder electron diffraction patterns
Authors: Gibbon Donald L. , Komlosi Beverly J. 
Published: June 2020

Incomplete powder electron diffraction patterns are traditionally difficult to interpret and are usually simply overlooked as being a sort of not-veryuseful background noise in the flow of data gathered in sample analysis. However, if techniques can be developed to systematize the information contained in those patterns, it can be a major contribution to the unravelling of complex materials problems. The following simple techniques are applied in our laboratories:1. Patterns are recorded on Technical Pan 35mm film, using a double-exposure to obtain a well-exposed record of the rings and spots; a very small central spot is exposed at much lower intensity with the beam stop removed. The film is developed at high contrast in HC-110, dilution F (1:9).
HVEM and conventional TEM studies of post-shadow labeled surface molecules in freeze-etch replicas
Authors: Dinchuk J. E. , T.J.A. Johnson , J.E. Rash 
Published: June 2020

Post-shadow labeling of freeze-etch replicas permits 3-dimensional molecular localization to within 10-30 nm. In this tutorial, we will describe methods of postshadow labeling as well as the use of simple systems for testing reagents and for evaluating the steps in this new methodology.Preparation of Murine Splenic LymphocytesMurine splenic lymphocytes are isolated by gentle disruption of fresh spleen and fixed in suspension by addition of glutaraldehyde to a final concentration of 2%. After two minutes, 1.0 M glycine is added to a concentration of 0.1 M and the cells are pelleted at 500 x g for 5 minutes.
Optical microscopy beyond the diffraction limit
Authors: Betzig Eric 
Published: June 2020

The near-field optical interaction between a sharp probe and a sample of interest can be exploited to image, spectroscopically probe, or modify surfaces at a resolution (currently down to ~12 nm with visible light) well beyond the diffraction limited response of traditional far-field systems. The resulting technique, near-field scanning optical microscopy (NSOM), still retains many of the attractive features of conventional optics, including non-invasiveness, low cost, reliability, and ease of use. Most importantly, NSOM takes advantage of the numerous and powerful contrast mechanisms and associated sample preparation procedures developed for optical microscopy over the last three centuries.Several applications have been investigated to demonstrate the versatility arising from these contrast mechanisms. For example, polarization contrast has been coupled with near-field surface modification capabilities to image and record domains in thin-film magneto-optic materials (Fig. 1). This might form the basis for a new method of ultra-high density optical data storage, or could be used in a study of domain wall energetics in magnetic systems.In the biological arena, NSOM has been used to image fluorescently labeled cytoskeletal actin in fixed mouse fibroblast cells (Fig. 2), and applied in a study of the actin organization within wound healing protrusions. The resulting images were also compared to topographic data arising from the shear force mechanism which regulates the probe-to-sample separation.
An improved method for ultrastructural examination of paraffin-embedded tissues for diagnostic purposes
Authors: Howard Tamara A. , Ziesmer Donna N. , Ries Ardith L. , Becich Michael J. 
Published: June 2020

Small cell tumors, liver and skin biopsies for metabolic disorders, soft tissue tumors and kidney biopsies are the paraffin embedded tissues most frequently requested for ultrastructural examination. Preservation of cell membranes, glycogen, mucopolysaccharides, glycoproteins, glycolipids and other soluble components is problematic in these cases. Causes of cellular extraction when processing paraffin embedded tissue are:a) inadequate fixation of carbohydrates, mucopolysaccarides, glycoproteins and glycolipidsb) extraction of lipids and cell membranes by polar solventsc) temperature effectsd) extraction of sugars and glycoproteins due to pH and non-buffered, hypo-osmolar solutions.A methodology which improves preservation is described below:1) Tissue samples are cut from paraffin blocks and deparaffinized in 2 changes of xylene at 4°C for 2-4 h (low temperature decreases extraction in solvent).2) The samples are then rehydrated through a decreasing series of acetone concentrations (5-10 min each) at 4°C to 2, 5-10 min changes of 0.1 M cacodylate buffer containing 14.4 mM sucrose and 3.5 mM CaCl2, pH 7.8 (less polar solvent -- acetone vs. ethanol -- should decrease lipid extraction thereby enhancing membrane preservation)
Application of high-resolution field-emission LVSEM, backscatter imaging, immunogold staining to definition of the spatial distributions of two human neutrophil adherence receptors
Authors: Nelson Robert D. , Hasslen Sharon R. , Erlandsen Stanley L. 
Published: June 2020

Receptors are commonly defined in terms of number per cell, affinity for ligand, chemical structure, mode of attachment to the cell surface, and mechanism of signal transduction. We propose to show that knowledge of spatial distribution of receptors on the cell surface can provide additional clues to their function and components of functional control.L-selectin and Mac-1 denote two receptor populations on the neutrophil surface that mediate neutrophil-endothelial cell adherence interactions and provide for targeting of neutrophil recruitment to sites of inflammation. We have studied the spatial distributions of these receptors using LVSEM and backscatter imaging of isolated human neutrophils stained with mouse anti-receptor (primary) antibody and goat anti-mouse (secondary) antibody conjugated to 12 nm colloidal gold. This combination of techniques provides for three-dimensional analysis of the expression of these receptors on different surface membrane domains of the neutrophil: the ruffles and microvilli that project from the cell surface, and the cell body between these projecting structures.
Immunocytochemical localization of a brush border hydrolase, lactase, in newborn suckling rat jejunum
Authors: Kömüves László G. , Dudley Mary A. , Nichols Buford L. 
Published: June 2020

Lactase-phlorizin hydrolase (LPH, EC 3.2.1.23), an integral membrane glycoprotein of the small intestinal brush border, converts lactose, the main carbohydrate in milk, to its monosaccharide components. Although the activity of LPH is high in suckling rats, little is known about its distribution within the intracellular compartments of the secretory pathway and brush border. We present the first description of the ultrastructural localization of LPH in the neonatal jejunum of suckling rat pups.Pieces of jejunum from 12- to 14-d-old suckling rat pups from three litters of Sprague- Dawley rats were fixed with 4% freshly prepared paraformaldehyde in 100 mM phosphate buffer, pH=7.40, for 4 h, and stored in 1% paraformaldehyde, at 4°C, until further processing. The samples were sectioned after cryoprotection in 2.3 M sucrose in an RMC MT-7 ultramicrotome equipped with CR21 cryoattachment. Ultrathin cryosections were collected on Formvar-coated, carbon-evaporated nickel grids. The nonspecific binding sites were blocked by 1% heat-inactivated newborn calf serum in 10 mM Trizma buffer, pH=7.60, containing 500 mM NaCl, 0.05% NaN3and 20 mM glycine (buffer A).
Freeze-fracture views of membrane motors of bacteria
Authors: Khan Shahid 
Published: June 2020

The locomotory organelles of many bacteria are long, helical filaments called flagella. Bacterial flagella rotate. Flagellar rotation is driven by a molecular motor that is part of the membrane embedded flagellar base and fueled by electrochemical proton (or sodium) gradients. Rapid-freeze electron microscopy has revealed that rings of intramembrane particles found clustered around flagellar bases are a key structural module of this motor.The morphology of the ring particles provides clues to their function. The particles are located in the cytoplasmic membrane across which the electrochemical gradients that energize flagellar rotation are maintained. In Escherichia coli, in addition to proteins needed for assembly of the flagellum, two proteins, MotA and MotB, are required for motility. MotA conducts protons across membranes and interacts with MotB, a protein with a large periplasmic domain. In non-motile mutants lacking MotA and MotB, flagellar bases lack the particle rings. Plasmid based expression of both MotA and MotB is necessary for restoration of motility and the ring structures.
The incenps: Chromosomal proteins with an essential cytoskeletal role during mitosis
Authors: Mackay Alastair M. , Chue Calvin , Mark Eckley D. , Earnshaw William C. 
Published: June 2020

The INCENPs (INnerCENtromereProteins - Mr133 and 145 kDa) are tightly bound to chromatin until early metaphase, and arrive at the metaphase spindle plate as integral components of the chromosomes (Cooke et al., 1987; Earnshaw & Cooke, 1991). It is thus surprising that the INCENPs leave the chromosomes during the latter part of metaphase to become associated with fibrous structures traversing the metaphase plate (presumably the overlapping polar microtubules of the spindle). Following the onset of anaphase, the INCENPs remain closely associated with the stem body material in the central spindle and also become associated with the inner surface of the cell membrane at the position where the cleavage furrow subsequently forms.By combining library screening with reverse-transcriptase PCR, we have recovered cDNA clones that contain the complete open reading frames (ORFs) of the two chicken INCENPs. Class 1 INCENP cDNA contains an ORF of 839 codons, which includes a predicted central coiled-coil domain of about 200 residues.
The dynamics of synapse formation: Time-lapse observations by confocal fluorescence microscopy in hippocampal slices and zebra-fish embryos
Authors: Smith Stephen J , Dailey Michael E. , Pike Susan , Buchanan JoAnn , Bergles Dwight E. 
Published: June 2020

Our present information about the formation of synapses in the central nervous system is based almost exclusively on observations of fixed tissue specimens. Such observations can only provide very limited inference about the dynamics of the underlying developmental processes. In the hopes of obtaining direct information about the dynamics of synapse formation, we have explored new methods that allow repeated, high-resolution optical imaging of synapse formation events in live neural tissues.Our efforts have focused on specific excitatory synapses in two vertebrate nervous systems: (1) the mossy-fiber-to-CA3-pyramidal-cell synapse in the hippocampus of postnatal day 4-8 rats and (2) the mauthner-fiber-to-motoneuron synapse in intact early embryos of the zebrafish Brachydanio rerio. We are using laser-scanning confocal fluorescence microscopy and fluorescent membrane stains such as di- I and di-O. Individual neurons or limited subsets of the neurons within a tissue are stained by applying these dyes in dimethylformamide solution through micropipettes.
High-resolution 3-D and 4-D imaging using wide-field CCD-based microscopy
Authors: Swedlow Jason R. , Scalettar Bethe A. , Sedat John W. , Agard David A. 
Published: June 2020

Because of the limited numerical aperture of a light microscope objective lens, every image recorded from a microscope is blurred and therefore degraded. This problem is particularly acute when a full three-dimensional image stack is viewed in projection. The blurred image is a convolution between every light source in an object and the point-spread function (PSF) of the objective lens and can be mathematically calculated or empirically measured. To eliminate blurring, we record three- and four-dimensional images with a charge-coupled device (CCD) -based computerized optical sectioning microscope and mathematically deconvolve out-of-focus photons using the appropriate three-dimensional, empirically measured PSF. The use of the empirical PSF is important because of the presence of a partial confocal effect in a wide field microscope caused by the presence of the field diaphragm. The advantage in this method is that collection and restoration of out-of-focus photons results in high sensitivity and resolution.In order to follow nuclear and chromosome dynamics, we have injected Drosophila melanogaster embryos with various fluorescent proteins and then monitored the distribution of these proteins during mitosis by recording a series of three-dimensional data sets at regular time intervals-- a four dimensional data set.
Confocal study of microaggregates in 2.5 billion year-old sediments
Authors: Fan G.Y. , Mojzsist S. , Arrheniust G. 
Published: June 2020

Light microscopy conducted on samples of Archean sediments reveals microaggregates (Fig. 1) which are suggestive of a biotic origin. These aggregates, typically 15 μm wide and 50 μm long, are thought to be the mineral remains of colonies of microorganisms that lived 2.5 billion years ago. Confocal microscopy is used to study the structures of these microaggregates in 3-D.Samples under study are from the lowest section drill core taken from the Dales Gorge Member of the Brockman Iron-Formation (Hamersley Basin) in Western Australia. These sediments are well preserved and escaped metamorphic conditions typically experienced by older rocks of this type. Two types of samples were prepared for study under the microscope: thin sections (~40 μm) for transmitted light microscopy to study the general rock texture and to locate the features of interest, and thick sections (3 mm) for confocal microscopy to determine the 3-D structure of the aggregates in their undisturbed state.
Image compression and data integrity in confocal microscopy
Authors: Avinash Gopal B. 
Published: June 2020

In confocal microscopy, one method of managing large data is to store the data in a compressed form using image compression algorithms. These algorithms can be either lossless or lossy. Lossless algorithms compress images without losing any information with modest compression ratios (memory for the original / memory for the compressed) which are usually between 1 and 2 for typical confocal 2-D images. However, lossy algorithms can provide higher compression ratios (3 to 8) at the expense of information content in the images. The main purpose of this study is to empirically demonstrate the use of lossy compression techniques to images obtained from a confocal microscope while retaining the qualitative and quantitative image integrity under certain criteria.A fluorescent pollen specimen was imaged using ODYSSEY, a real-time laser scanning confocal microscope from NORAN Instruments, Inc. The images (128 by 128) consisted of a single frame (scanned in 33ms), a 4-frame average, a 64-frame average and an edge-preserving smoothed image of the single frame.
Gum arabic helps prepare better lacey polymer films for specimen support in electron microscopy
Authors: Sheth Shailesh R. , Bellare Jayesh R. 
Published: June 2020

Specimen support and astigmatism correction in Electron Microscopy are at least two areas in which lacey polymer films find extensive applications. Although their preparation has been studied for a very long time, present techniques still suffer from incomplete release of the film from its substrate and presence of a large number of pseudo holes in the film. Our method ensures complete removal of the entire lacey film from the substrate and fewer pseudo holes by pre-treating the substrate with Gum Arabic, which acts as a film release agent.The method is based on the classical condensation technique for preparing lacey films which is essentially deposition of minute water or ice droplets on the substrate and laying the polymer film over it, so that micro holes are formed corresponding to the droplets. A microscope glass slide (the substrate) is immersed in 2.0% (w/v) aq. CTAB (cetyl trimethyl ammonium bromide)-0.22% (w/v) aq.