bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microwave fixation of cells in culture for scanning electron microscopy
Authors: Chew E.C. , Riches D.J. , Tam P.P.L. , Tsao G.S.W. , Lam T.K. , Hou-Chan H.J. 
Published: June 2020

The use of microwave irradiation for fixation of human and animal tissue has been proven satisfactory at light microscopic and electron microscopic levels. The present communication reports the study of the same method of fixation of cell cultures for scanning electron microscopy.Trophoblasts were isolated from the placentae of mouse conceptuses at 10.5 days of gestation. The placenta was dissected out from the decidua and placed in Ca and Mg-free PBS, minced and then forced through a gauge-21 syringe needle. The tissue fragments were digested with 0.25% trypsin in Ca and Mg-free PBS for 20 - 30 minutes at 4°C. The digested tissue was then washed with complete PB1 medium. A single-cell suspension was obtained by spinning down the larger fragments by centrifugation. A known volume of the single-cell suspension was added to the culture medium (DCMEM and 20% FCS). The culture medium was changed after 24 hours to remove any unattached cells.
Automated image analysis applied to freeze-fracture replicas of Tetrahymena
Authors: Hufnagel Linda 
Published: June 2020

Quantitative studies on intramembranous particle (IMP) frequencies and size distributions have been found to be valuable for the analysis of dynamic changes in membrane structure and function (c.f. 1,2,3). However, few such quantitative studies have been exhaustive because of the tedious and timeconsuming measurements required. The process can also be expensive, if one has to make special enlargements of photographs for accurate measurement.I wished to examine the effects of various environmental factors, developmental sequences and preparative conditions on the frequency, size distribution, spatial distribution and orientation of IMPs in various regions of the plasma membrane of Tetrahymena, a ciliated protozoan ideally suited to studies on aging, cell-cell interactions, development of pattern and effects of toxic chemicals, whose membrane structure I have already characterized in some detail using freeze-fracture and freeze-etch methods. Both manual measurement and semiautomatic image analysis seemed out of the question for the numerous samples which would have to be analyzed and the large number of particles required for statistically meaningful results.
Ultrastructural studies on aortic paraganglioma
Authors: Sun C. N. , Schaefer R. 
Published: June 2020

Aortic paraganglioma is a rare tumor of the superior mediastinum. The first report of aortic paraganglioma in humans was made by Lattes in 1950. Since then, there have been 40 cases published, however, ultrastructural studies are few, only one report came to our attention. For this reason, the present investigation was undertaken.The aortic paraglanglioma mass was removed from a 47 year old white male and specimen was fixed in glutaraldehyde, then post-fixed in osmium tetroxide. After dehydration, tissues were embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate. The spherical encapulated tumor mass measing 4x5 cm had a tannish gray, homogeneous appearance. The cells are arranged into alveolar-like clusters or nests, which were separated by narrow bands of connective tissue and blood vessels. Collagen fibrils and long space fibrous collagen were occasionally found in the connective tissue, while endothelial cells and pericytes were found in the blood vessels. There were two types of tumor cells in the alveolar-like clusters: sustentacular cells and chief cells (Fig. 1). The sustentacular cells were in juxta position to large polyhedral shaped chief cells.
Ultrastructural investigation of spontaneous pituitary gonadotroph cell adenomas in aging Sprague-Dawley rats
Authors: McComb D. J. , Beri J. , Zak F. , Kovacs K. 
Published: June 2020

Gonadotroph cell adenomas of the pituitary are infrequent in human patients and are not invariably associated with altered gonadal function. To date, no animal model of this tumor type exists. Herein, we describe spontaneous gonadotroph cell adenomas in old male and female Sprague-Dawley rats by histology, immunocytology and electron microscopy.The material consisted of the pituitaries of 27 male and 38 female Sprague Dawley rats, all 26 months of age or older, removed at routine autopsy. Sections of formal in-fixed, paraffin-embedded tissue were stained with hematoxylin-phloxine-saffron (HPS), the PAS method and the Gordon-Sweet technique for the demonstration of reticulin fibers. For immunostaining, sections were exposed to anti-rat β-LH, anti-ratβ-TSH, anti-rat PRL, anti-rat GH and anti-rat ACTH 1-39. For electron microscopy, tissue was fixed in 2.5% glutaraldehyde, postfixed in 1% OsO4 and embedded in epoxy-resin. Tissue fixed in 10% formalin, embedded in epoxy resin without osmification, was used for immunoelectron microscopy.
Multivariate classification of diffraction patterns: Effects of different stains on images of mitochondrial pore arrays
Authors: Frank Joachim , Mannella Carmen 
Published: June 2020

Correspondence analysis has previously been used for classifying images of single macromolecules.In these applications, each individual image is represented by a N-dimensional vector where N is the number of pixels selected by an area-of-interest mask. Clustering of images may be detected by projecting these vectors into a suitably chosen, low-dimensional subspace. In the current work, this analysis is extended to diffraction information.Subject of this study are the characteristic stain-dependent changes in appearance of the pore arrays in outer membranes of N. crassa mitochondria.3 Since the stain moeities active in solution carry different charges at different pH, the different staining patterns may be indicative of surface charges of the pore protein and lipid.Although different patterns of stain distribution can be distinguished in the Fourier filtered images, there is a considerable amount of scattering within each experimental set. This has led us to search for a method that would allow the grouping of experimental data to be assessed, and the significance of structural differences to be established. In principle, correspondence analysis of the filtered images would achieve this goal.
Three-dimensional reconstruction of the 30S ribosomal subunit from randomly oriented particles
Authors: Verschoor A. , Frank J. , Radermacher M. , Wagenknecht T. , Boublik M. 
Published: June 2020

The small (30S) subunit of prokaryotic ribosomes can assume any of a wide range of tilt positions on the specimen support. Correspondence analysis should make it possible to order views appearing in the electron micrograph according to the angle of tilt.231 individual windowed images from two micrographs showing negatively stained 30S subunits from E. coli ribosomes were subjected to multireference alignment. Correspondence analysis yielded six morphologically significant factors of variance. The second of these related to variations in stain concentrations, which are irrelevant at the level of gross morphology. The coordinates for each image in five-dimensional space (relating to factors 1,3,4,5, and 6) were subjected to a nonlinear mapping algorithm, which calculated an optimal two-dimensional map.The resulting distribution (Fig 1) consisted of two clusters, one of rightfacing, the other of left-facing views. Subaverages along the outer margin of the cluster on the left showed the particle in a range of typical views.
A Stable Field Emission Electron Source
Authors: Bottoms W.R. , Haydon G.B. 
Published: June 2020

There is great interest in improving the brightness of electron sources and therefore the ability of electron optical instrumentation to probe the properties of materials. Extensive work by Dr. Crew and others has provided extremely high brightness sources for certain kinds of analytical problems but which pose serious difficulties in other problems. These sources cannot survive in conventional system vacuums. If one wishes to gather information from the other signal channels activated by electron beam bombardment it is necessary to provide sufficient current to allow an acceptable signal-to-noise ratio. It is possible through careful design to provide a high brightness field emission source which has the capability of providing high currents as well as high current densities to a specimen. In this paper we describe an electrode to provide long-lived stable current in field emission sources.The source geometry was based upon the results of extensive computer modeling. The design attempted to maximize the total current available at a specimen.
Backscattered Electron Spectroscopy with a Si(Li) Detector
Authors: Russ J.C. 
Published: June 2020

Solid state lithium-diffused silicon detectors are commonly used as energy-dispersive X- ray detectors. These devices will, however, produce electrical pulses with a height proportional to the energy of electrons (and other particles) as well. We have used a Si(Li) detector with conventional electronics (amplifier, multi-channel pulse-height analyzer) to measure the energy spectrum of electrons backscattering from pure elements with atomic numbers from 12 (Mg) to 92(U).Since the electron beam striking the target also generates X-rays (characteristic and continuum) that are measured by the detector along with the backscattered electrons, and since it is not possible to stop the X-rays from reaching the detector while allowing the electrons to pass, we measured the electron spectrum by difference. Figure 1 shows superimposed, the spectra (for a copper target) of X-rays plus electrons (upper curve) and X-rays only (lower curve), the latter obtained with the use of a magnetic electron trap in front of the detector.
The Role Of Dislocations And Related Crystal Defects In Providing Preferential Sites For Bacterial Attachment To Mineral Surfaces
Authors: Murr L.E. , Berry V.K. 
Published: June 2020

It has recently been shown that bacteria involved in the catalysis of leaching reactions which convert insoluble sulfides in copper-bearing ores to water soluble sulfates not only attach to the mineral surface under certain conditions, but that in porphyry copper ores where CU2S, CuFeS2, and FeS2 phase regions are disseminated throughout quartz monzonite, feldspar, or related host-rock matrices, the attachment is observed to occur only on the exposed sulfide phase surfaces, and not on the matrix or host-rock surface1,2. This selective attachment of microorganisms to specific chemical regions as a result of the necessity to sustain rather specific and rather delicate microbial metabolisms raises interesting questions about the initial surface site preference for the attachment of individual microorganisms.Murr and Berry3,4 have postulated that dislocations might serve as initial attachment sites, or that as a result of defect-induced variations in surface energy or volume energy, groups of dislocations might provide preferential sites for initial bacterial attachment.
An Electron Microscopic Study Of Some Solid-State Polymerization Reactions
Authors: Jones William , Thomas John M. , Livesley David A. 
Published: June 2020

There is interest at present amongst organic solid-state chemists in producing, through topochemical reaction, stereoregular and crystalline polymers of high molecular weight. In certain reactions the geometry of the polymer product and the high degree of crystallinity are completely determined by the molecular packing in the monomer crystal (1). In others, however, low molecular weight product or products not predicted from a knowledge of the monomer packing have lead to suggestions that dislocations or other regions of imperfection may be important as sites of initiation of reaction or possibly of nucleation of the formed polymer (2). Defects will also control the length of the formed polymer (2).We have utilized transmission electron microscopy for investigating defects in anthracene and some of its derivatives, which also undergo chemical and photo-induced reactions, occasionally in a manner not determined by the perfect crystal lattice (3). Consequently we felt it appropriate to observe by TEM foils of monomer before, during and after polymerization.
Characterization of Deposits on Silicone Contact Lenses from Clinical Wear Studies
Authors: Freeman H. , Berta R. 
Published: June 2020

Contact lenses made from silicone elastomer have been made and tested because of the inherent permeability of silicones to gases. Adequate transfer of such gases as oxygen and carbon dioxide through the Silcon® lens tends to minimize metabolic imbalance at the cornea. This property offers the potential for comfortable extended wear of Silcon® lenses. However, as in other man-made materials interacting with body processes, silicone contact lenses are subject to the accumulation of biological materials which gradually impair visual acuity. Morphological and chemical information about the accumulation has been gained by the use of replication electron microscopy, scanning electron microprobe; and identification of biological species by mass spectrometry.Silicone contact lenses were dispensed to patients in the course of an experimental clinical program during which frequent examinations were made of the patient's eyes and lenses. Lens care regimens were carefully specified.
Defocused Images Of Electrostatic And Magnetic Edges
Authors: Mory C. , Colliex C. 
Published: June 2020

Fresnel fringes are a common feature in CTEM defocused images of specimen edges. The detailed contrast is actually governed by the exact geometry of the termination of the edge. Calculations by Fert and Laffite (1) and by Fukushima et al (2) have shown that the intensity profile is very sensitive to the existence of a region of thickness gradient. Joy et al (3) have clearly interpreted these contrast variations as a consequence of the refraction of the electrons in this zone.In order to determine how far these effects can be used to evaluate physical parameters of an edge, we have computed images of thin electrostatic or magnetic edges to fit them with experimental observations. An optical model with a pure phase or a mixed phase^and amplitude object is used. The structure of the wave function a on the exit surface of the specimen forms the input signal for the subsequent electron optical imaging system which involves spherical and defocusing aberrations.
Instrumentation For Quantitative Microscopy
Authors: Ralph B. , Jones A.R. 
Published: June 2020

In all fields of microscopy there is an increasing interest in the quantification of microstructure. This interest may stem from a desire to establish quality control parameters or may have a more fundamental requirement involving the derivation of parameters which partially or completely define the three dimensional nature of the microstructure. This latter categorey of study may arise from an interest in the evolution of microstructure or from a desire to generate detailed property/microstructure relationships. In the more fundamental studies some convolution of two-dimensional data into the third dimension (stereological analysis) will be necessary.In some cases the two-dimensional data may be acquired relatively easily without recourse to automatic data collection and further, it may prove possible to perform the data reduction and analysis relatively easily. In such cases the only recourse to machines may well be in establishing the statistical confidence of the resultant data. Such relatively straightforward studies tend to result from acquiring data on the whole assemblage of features making up the microstructure. In this field data mode, when parameters such as phase volume fraction, mean size etc. are sought, the main case for resorting to automation is in order to perform repetitive analyses since each analysis is relatively easily performed.
A New System For Optomanual Semiautomatic Quantitative Image Analysis
Authors: Rohr H.P. 
Published: June 2020

Today, in image analysis the broadest possible rationalization and economization have become desirable. Basically, there are two approaches for image analysis: The image analysis through the so-called scanning methods which are usually performed without the human eye and the systems of optical semiautomatic analysis completely relying on the human eye.The new MOP AM 01 opto-manual system (fig.) represents one of the very promising approaches in this field. The instrument consists of an electronic counting and storing unit, which incorporates a microprocessor and a keyboard for choice of measuring parameters, well designed for easy use.Using the MOP AM 01 there are three possibilities of image analysis:the manual point counting,the opto-manual point counting andthe measurement of absolute areas and/or length (size distribution analysis included).To determine a point density for the calculation of the corresponding volume density the intercepts lying within the structure are scanned with the light pen.
Stereological Analysis Of Sem Images
Authors: Schmiβer H. S , Swensson R. A. 
Published: June 2020

Development of new signal detection systems for STEREOSCAN scanning electron microscopes has greatly increased the applicability of quantitative image analysis to pictures obtained with an s.e.m. While quantitative image analysis has proven to be a powerful technique to draw quantitative information from pictures obtained from light microscopes as well as various other sources of images, the field of scanninq electron microscopy has largely been uncovered in the past.This was mainly due to the particular appearance of “normal” s.e.m. pictures. Exactly those features which make s.e.m. pictures easy to interpret intuitively an aesthetically attractive i.e. the pseudo three dimensional appearance made it virtually impossible to treat these images with the well known methods of electronic image analysis.
Scanning Electron Microscopy of an 8 μm Thick ZrO2 Film
Authors: Ploc R.A. , Miller M.A. 
Published: June 2020

This abstract reports the occurrence of 'breakaway oxidation' for unalloyed zirconium in 300°C oxygen. An excellent review of zirconium and zirconium alloy oxidation can be found elsewhere (1).Approximately one dozen crystal bar zirconium coupons were placed in a resistance wound furnace held at 300°C and through which oxygen (initially passed through a silica gel dessicant) was passed. Over a period of three years, the samples accumulated over 700 days of oxidation time. The kinetics followed a rate law between cubic and parabolic until achieving an oxide thickness approximately 350 nm at which point 'breakaway' occurred. For instance, in one year the film increased in thickness from 0.35 to more than 8 μm. These thick, post-transition oxides were examined in the SEM.The samples were characterized by regions approximately 40 μm in diameter which spalled with a density of about 45 per cm2.
Dislocation Substructures Produced During Tensile, Creep, and Fatigue Deformation of Ti3Al at 700°C
Authors: Sastry S. M. L. 
Published: June 2020

Ti3Al is an ordered intermetallic compound having the DO19-type superlattice structure. The compound exhibits very limited ductility in tension below 700°C because of a pronounced planarity of slip and the absence of a sufficient number of independent slip systems. Significant differences in slip behavior in the compound as a result of differences in strain rate and mode of deformation are reported here.Figure 1 is a comparison of dislocation substructures in polycrystalline Ti3Al specimens deformed in tension, creep, and fatigue. Slip activity on both the basal and prism planes is observed for each mode of deformation. The dominant slip vector in unidirectional deformation is the a-type (b) = <1120>) (Fig. la). The dislocations are straight, occur for the most part in a screw orientation, and are arranged in planar bands. In contrast, the dislocation distribution in specimens crept at 700°C (Fig. lb) is characterized by a much reduced planarity of slip, a tangled dislocation arrangement instead of planar bands, and an increased incidence of nonbasal slip vectors.
Origin of Voids in Thin Films
Authors: Nakahara S. 
Published: June 2020

A recent transmission-electron-microscope (TEM) study has shown, using the defocus contrast technique, that thin evaporated gold films contain a high density of small voids.In this communication, we report a TEM study on the structure and distribution of voids in thin films prepared by evaporation, sputtering, and electrodeposition and discuss a possible mechanism, by which voids are generated during film growth.In evaporation, sputtering, and electrodeposition processes, the entrapment of gaseous and/or organic impurities at growing film surface cannot be avoided due to their relatively unclean environment. Such impurity entrapment could take place conveniently at surface irregularities such as growth steps, grain boundaries and valleys between aggregates of crystallites. The incorporation of trapped impurities, therefore, results in the formation of voids at the above three sites. It can be easily seen that the spacial distribution of voids generated at grain boundaries should closely follow the grain structure of thin films.
Fine Microstructure of a Mechanically Alloyed Oxide Dispersion Strengthened Nickel-Base Superalloy
Authors: Marti Jordi , Howson Timothy E. , Kratz David , Tien John K. 
Published: June 2020

The previous paper briefly described the fine microstructure of a mechanically alloyed oxide dispersion strengthened nickel-base solid solution. This note examines the fine microstructure of another mechanically alloyed system. This alloy differs from the one described previously in that it is more generously endowed with coherent precipitate γ forming elements A1 and Ti and it contains a higher volume fraction of the finely dispersed Y2O3 oxide. An interesting question to answer in the comparative study of the creep and stress rupture of these two ODS systems is the role of the precipitate γ' in the mechanisms of creep and stress rupture in alloys already containing oxide dispersoids.The nominal chemical composition of this alloy is Ni - 20%Cr - 2.5%Ti - 1.5% A1 - 1.3%Y203 by weight. The system receives a three stage heat treatment-- the first designed to produce a coarse grain structure similar to the solid solution alloy but with a smaller grain aspect ratio of about ten.
A Scanning Electron Microscopy Study of the Attachment of a Thromboresistive Surface Coating to a Membrane Blood Oxygenator
Authors: Borovetz H. S. , Matta R. K. , Goitein K. J. , Hung T.-K. , Weissman M. H. , Hardesty R. L. 
Published: June 2020

The need for systemic heparin anticoagulation during extended cardiopulmonary bypass (CPB) remains a serious impediment to clinical CPB support of circulatory and respiratory failures, especially in the newborn. Recent development of thromboresistive substrates which can be used to treat extracorporeal surfaces in contact with blood offers the potential for elimination of systemic blood heparinization. The present paper describes a scanning electron microscopy study of the attachment of one such substrate, tridodecyl- methylammonium chloride (TDMAC), to a novel micro-membrane oxygenator.Figure 1 shows a cross-sectional image of the alternating pattern of microchannel conduits for blood flow through the oxygenator. The micro-channels were fabricated on thin metal sheets with an approximate semi-circular shape (150 + 25 microns in radius). The gas exchange to the blood flow in the channels was accomplished through a micro-porous membrane which was placed across the diametric plane of the channels (1).