bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endocytosis and Digestion in Entamoeba Histolytica.
Authors: Lushbaugh W.B. , Kairalla A.B. , Pittman J.C. , Pittman F.E. 
Published: June 2020

Internalization of particulates and liquids (endocytosis) and the assymilation of ingested foodstuffs have been well documented for several free living amebae (Pelomyxa and Acanthamoeba). Less is known about these processes in the human parasitic ameba, Entamoeba histolytica.Axenically cultivated trophozoites of E. histolytica, strain HM-1:IMSS, were studied by transmission electron microscopy of thin sections and freeze-etch replicas prepared from cells incubated (5 min to 3 hr) with latex beads, erythrocytes or bacteria.Tubular channels formed by plasmalemma invagination appeared to be associated with pinocytosis (Fig. 1). These were similar to the pinocytotic channels described by Chapman-Andreson and Nilsson for Pelomyxa.
Scanning Electron Microscopy of Blaberus Giganteus (L.) Maxillary Palp Sensilla
Authors: Dailey P. 
Published: June 2020

The maxillary palps of B. giganteus are located on the maxillae which lie between the labrum and labium. They are modified appendages used in feeding. Each appendage bears 5 segments, the most distal of which contains the palp organ or sensory pad (Fig. 1). The maxillary palps were fixed in 2.5% glutaraldehyde in 0.05 M sodium cacodylate buffer (pH 7.1) containing .15 M sucrose and post-fixed in 1% osmium tetroxide in buffer. This was followed by dehydration and critical point drying. Cryofractography was performed on some of the palp organs prior to drying (1).The sensory pad is composed of an exocuticular membrane upon which lie numerous sensilla basiconica in an elliptical pattern on the ventral surface. The membrane enables the sensory pad to expand and, in living specimens it appears dome-like due to the pressure exerted on it by the hemolymph.
Comparison of Several Sem Imaging Modes in Studying Intracellular Particulates in the Lung
Authors: Abraham J. L. , Miyai K. 
Published: June 2020

The scanning electron microscope (SEM) offers several signal modes, each of which may contain unique information about the specimen. In this paper we demonstrate and compare the merits of the familiar secondary electron (SE) mode, the backscattered electron (BSE) mode, and x-ray distribution mapping.Lungs of hamsters treated intratracheally with the radiographic contrast medium tantalum suspended in carboxymethyl cellulose were fixed with intratracheal buffered 2% glutaraldehyde. Blocks were razor cut to a few mm, dehydrated and critical point dried. The dried blocks were mounted on aluminum SEM studs and coated with carbon,, followed in some instances by gold/palladium (60/40). Examination at 20 kv and 45° specimen tilt was done in an Etec SEM with a solid state BSE detector and a Cambridge S4 SEM with an ORTEC energy dispersive x-ray analysis system.
Alpha-1-Antitrypsin Deficiency: An Ultrastructural Case Study
Authors: Simons P. K. 
Published: June 2020

Alpha-1-antitrypsin is a broad spectrum protease inhibitor produced by the liver. It accounts for 90% of the serum alpha-1 globulins. Normal serum levels of alpha-1-antitrypsin are 200-400 mg/100ml. The protease inhibitor serum level shows a distinct rise in response to tissue injury. Activity with chymotrypsin, elastase, hyaluronidase, skin collagenase, plasmin, and thrombin has been reported. It may have a role in providing protection to normal tissues by neutralizing enzymes released from dying cells as a result of injury or inflammation.Deficiency of alpha-1-antitrypsin is inherited as an autosomal recessive. Phenotype is determined by electrophoretic mobility in Starch-Gel electrophoresis. Normal individuals show M bands (for medium speed) and the homozygous dominant phenotype is designated PiMM. Two other electrophoretic migratory bands are observable in different phenotypes of this protease inhibitor: the S band (slower mobility than the M band) and the Z band (slowest).
Unusual Inclusions in Neutrophils of two Human Renal Allografts
Authors: Valenzuela R. , Deodhar S.D. , Osborne D.G. , Braun W.E. , Banowsky L.H.W. 
Published: June 2020

During a retrospective light and electron microscopy study of 158 human renal allograft biopsies, we observed, in two cases, unusual inclusions in the neutrophils trapped in glomeruli and paratubular capillaries. For electron microscopy, the specimens were fixed in glutaraldehyde, post-fixed in osmium tetroxide and embedded in Epon. Thin sections were stained with uranyl acetate and lead citrate. Eighty-six of the electron microscopically examined biopsies did not contain any neutrophils for evaluation, and only 10 biopsies showed four or more neutrophils.The two patients, A age 35 and B age 42, had received a cadaver donor renal allograft because of chronic renal failure secondary to hereditary nephritis and nephrosclerosis respectively. Neither patient was affected by any known primary blood disorder.
Intracisternal Membranes in Tumor Cells
Authors: Chew E.C. , Sun C.N. , White H.J. 
Published: June 2020

To our knowledge, membranous structures have not been heretofore reported in the cisternae of granular endoplasmic reticulum. Such unusual structures were seen in the course of study of Chang's hepatoma cells (1).The tumor cells from Chang's hepatoma were kindly given us by Professor J.P. Chang and carried in our laboratory by subcutaneous transplantations. Tissue fragments were fixed in 4% phosphate buffered glutarladehyde and post-fixed in 1% osmium tetroxide. Routine procedures were followed for dehydration and embedding in Epon 812. Sections were stained with uranyl acetate and lead citrate.As cited above, cisternal membranous structures were observed (Fig. 1), and similar structures were seen in the perinuclear cisternae (Figs. 2&3). The latter were devoid of ribosomes. In some instances, these membranes were not connected to the original membranes of the granular endoplasmic reticulum, while in many cases they were fused with the pre-existing membranes forming two separate cisternae (Figs. 1,2&3). These structures were also seen in hepatoma cells undergoing mitosis (Fig. 4).
Ultrastructural Effects of Acute Kepone Treatment in Rats
Authors: Klein Richard L. , Thureson-Klein Åsa K. , Mehendale Harihara M. 
Published: June 2020

KeponeR (decachlorooctahydro-1,3,4-metheno-2H-cyclobuta[cd]pentalen-2-one) is an insecticide effective against ants and roaches. It can cause severe toxicity in fishes, birds, rodents and man. Prominent effects include hepatic lipid deposition and hypertrophy, impairment of reproductive capacity and neurological disorders. Mitochondrial oligomycin-sensitive Mg2+-ATPase is also inhibited. The present study is a preliminary investigation of tissue ultrastructural changes accompanying physiological signs of acute toxicity, which after two days treatment include: pronounced hypersensitivity and tremor, various degrees of anorexia and adipsia, and decreased weight gain.Three different series of adult male Sprague-Dawley rats (Charles River or CD-I) were treated by intubation with Kepone in corn oil at a dose of 50 mg per kg for 3 successive days or at 200 ppm in food for 8 days. After ether anesthesia, rats were immediately perfused via a cannula in the left ventricle with 4% p-formaldehyde and 0.5% glutaraldehyde in Millonig's phosphate buffer at pH 7.2 for 20-30 min at 22°C.
Electron Microscopic Studies of Labeled Nucleic Acids
Authors: Cole M. D. , Rose S. D. , Wiggins J. W. , Beer M. 
Published: June 2020

Quantitative conversion of cytosine nucleotides to N4-furfuryloxy derivatives followed by reaction with osmium tetroxide plus bipyridine yields an electrondense stain suitable for visualization in the electron microscope. Chemical analysis shows that two osmium atoms become attached to each furan-modified cytosine nucleotide. Osmium tetroxide also reacts with thymine and uracil nucleotides, resulting in the attachment of one osmium atom each. Therefore the treatment of cytosine-modified nucleic acids with osmium tetroxide should allow recognition of cytosine and thymine nucleotides.Nucleic acids labeled with osmium by the above reactions have been viewed in a high resolution STEM. The signal used to form the image is the ratio of the elastically scattered intensity to the unscattered and ineiastically scattered intensity. The dosage that yields a signal to noise ratio sufficient for focussing is >104electrons/ Å2.
A Simple Device for Tissue Dehydration: Application of Concentration Gradient Generator
Authors: Goldfarb D. , Miyai K. , Hegenauer J. 
Published: June 2020

We describe a simple device for dehydrating tissue for electron microscopy. Devices of the same general configuration are widely applied in chromatographic separation and density gradient centrifugation, which requires the generation of simple concentration gradients in a continuous rather than stepwise fashion. The application of this technique to tissue dehydration saves time and expense compared to manual and commercially available mechanical methods.The device consists of two parts: I. a gradient generator, and II. a tissue tray (Fig. 1). The upper part of the device consists of the concentration gradient generator, composed of reservoirs A, B, C and Delrin plate D. Torus A and cylinder B are connected by a channel E. Stopcock F permits independent filling of the reservoirs.
Histochemical Staining of Semi-Thin Sections after Removal of Epoxy Resins
Authors: Lloyd Bolivar J. , Fultz Doris G. , Armstrong Caroline E. V. , Julio Martinez A. 
Published: June 2020

Casanova (19 74) has reported that the method of Mayor (19 61) is the best f or removal of epoxy resins. In her method, sodium methylate was made using sodium metal. We have modified this using sodium methylate powder.1. 5 gm of sodium methylate was dissolved in a beaker in 2 5 ml of methyl alcohol. As it dissolves the beaker becomes warm. When completely dissolved, 2 5 ml of benzene is added with stirring. If rings appear at the interface, mo re alcohol should be added until the rings disappear.
Effects of Vinblastine on the Structure and Function of the Rat Exorbital Lacrimal Gland
Authors: Kelly Robert B. 
Published: June 2020

Antimicrotubular agents such as vinblastine and colchicine have been used to assess the role of cytoplasmic microtubules in secretory processes (for review, see 1). The purpose of this study was to determine the effects of vinblastine on the structure and function of resting and pilocarpine- stimulated acinar cells of the rat exorbital lacrimal gland.Rats were divided into four groups: (a) untreated control; (b) vinblastine (4 mg/kg) treatment for 1 to 24 hours; (c) pilocarpine (20 mg/kg) treatment for 1 hour; and (d) vinblastine treatment for 1 hour, followed by pilocarpine treatment for 1 hour. Both drugs were administered via single intraperitoneal injections. The glands were fixed by perfusion and processed for electron microscopy.
The X-Ray Multichannel Analyzer
Authors: Schamber F. H. 
Published: June 2020

The multichannel analyzer (MCA) is a necessary instrument for the effective utilization of a solid-state X-ray detector. The designation MCA is commonly applied to any instrument which can accumulate a digitized spectrum within an internal storage memory; each individual storage “channel” of this memory represents the amplitude of a discrete data point of an acquired spectrum. The functions of a multichannel analyzer can be broken down into 3 major divisions:1. data acquisition2. display and readout3. data manipulation and reductionThe most important acquisition mode for X-ray spectroscopy is known as Pulse Height Analysis (PHA). In this analysis mode the fast, random pulses generated by the front-end detector electronics (detector, preamplifier, amplifier) are sorted by amplitude via a specialized analog to digital converter (ADC) and corresponding channels of the analyzer memory are incremented for each event.
Characterization of Cotton Dust by Elemental Analysis
Authors: Fleming E. , Tucker P. , Hersh S. 
Published: June 2020

Cotton dust has been identified as one of five common substances present in the workplace that a r e significant health hazards to industrial workers . The material reported here is part of a larger program being conducted by the School of Textiles to identify the etiological agent(s) causing byssinosis and to characterize the dust associated with cotton processing (1-3). The early results quickly verified that there are large amounts of both soluble and insoluble inorganic matterin cotton dusts.Electron diffraction patterns were obtained from dust samples collected directly on carbon-coated grids from the air and from -water dispersed samples collected by a filtration system located in a model cotton card room (4). Identification of these diffraction patterns has not yet been completed because our attention has now focused on examining the water extractable components of cotton dusts with a newly acquired EDS-SEM system.
In-Situ Analysis of the Trajectories and Speed of Gold Clusters Moving on Electron-Beam Cleaved (001) Mgo Surfaces.
Authors: Heinemann K. , Metois J.J. , Poppa H. 
Published: June 2020

A previously described high-resolution TEM with UHV specimen chamber (10-7 Pa range), electron beam evaporation facilities, and fast speed/low electron exposure image recording facilities (1,2) was employed to observe the mobility of small gold clusters (13 Å mean diameter) on electron-beam cleaved MgO substrates (3). A deposit of 1.3 x 1015 gold atoms/cm2 was evaporated in 60 seconds immediately following the cleavage.During the first 10 minutes following the deposition, many cluster mobility events were observed. The movements can be classified in two categories. One type of cluster mobility leads to coalescence and occurs usually within a few seconds (25 Å/s speed), see Fig.l. Whereas this kind of mobility was found to be predominant in previous cluster mobility studies of silver on amorphized graphite (4), cluster mobility leading to coalescence was only found in less than 20% of the observed mobility events for gold on (001) MgO. The majority of the cluster movements in the present system were characterized by an obvious tendency to avoid the proximity of other clusters (5).
“In-Situ” Dislocation Channeling Studies in Neutron-Irradiated Molybdenum
Authors: Narayan J. , Noggle T. S. 
Published: June 2020

Dislocation channels in neutron-irradiated molybdenum were first observed by Mastel, et al. (l) and later studied in more detail by Brimhall (2). Both of these studies were carried out on material deformed in bulk in which the channels were formed prior to preparation of microscope specimens. The present study employed Mo specimens which had been irradiated and deformed as bulk specimens, leading to dislocation channel structures of the type studied earlier, however, additional deformation has been introduced “in-situ” in the electron microscope to obtain information on the basic processes associated with dislocation channeling.Fig. 1(a-c) shows the growth of the original channels Al and A2 with deformation in the microscope. The channels are widened by the passage of dislocations of one type, b=a/2[111], indicating that cutting mechanisms are not solely responsible for the removal of the dislocation loops since the dislocations cannot eliminate loops of all possible Burgers vectors by cutting reactions.
Image Contrast for Dark-Field Stem
Authors: Cowley J. M. 
Published: June 2020

It has been stated or argued by a number of authors that the image contrast for dark-field scanning transmission electron microscopy, using an annular detector, may be interpreted as for an incoherent imaging process in that the image intensity is given by convolution of the square of a specimen scattering function with a beam intensity distribution function:IDF(r) = ϕ2 (r) * |g(r)|2 (1)It has further been stated that this "linear" relationship applies even for strong phase objects (1).It is necessary to evaluate the approximations on which these conclusions are based in order to determine their validity as a basis for quantitative image evaluation and image processing procedures. A straightforward analysis reveals that the most important limitations to the assumption of a relationship such as equation (1) arise because (a) it is valid only for weakly scattering objects and (b) it assumes that the intensity detected by the annular detector is proportional to the total scattered intensity.
Proposed Scheme for a Directional Low-Loss Detector
Authors: Wells Oliver C. 
Published: June 2020

The conventional low-loss electron detector (1,2) is shown in Fig. 1. The electron beam strikes the specimen with a glancing angle of typically between 30° and 45°. The input grid G1 is held at +200V. The filter grid G2 is held at +200V to collect secondary electrons or at -19.8kV for low-loss work with an incident beam energy of 20keV. The scintillator is held at +10kV for secondary electron detection or at -10kV for low-loss work. Comparison pairs of micrographs are obtained by recording one image in each mode. The signalto- noise ratio is approximately the same in each case.We are proposing to replace the single scintillator/light-pipe/photomultiplier system with a pair of such assemblies separated by a partition, such that an input electron will reach one or other of the scintillators, depending on which part of the input aperture it enters. The video waveform will be obtained using a sum-or-difference unit connected to the two photomultipliers.
Observations of Direct Non-Vertical Interband Transitions in Al and Si by Electron Energy-Loss Spectroscopy.
Authors: H. Chen C. , Silcox J. 
Published: June 2020

Electron energy-loss spectra (at 75keV) of single crystal aluminum and silicon foils of [001] orientation were obtained by using an electron microscope (Hitachi HU-11A)-electron spectrometer (Wien filter) system. The operation of this apparatus has been described previously. In the present experiment, the microscope was operated in the selected-areadiffraction mode and the energy-loss spectra were recorded on photographic plates and subsequently obtained data by microdensitometry.Figure 1 shows the loss spectrum in aluminum with momentum transfer q in the <100> direction. In addition to the usual bulk plasmons at 15eV and surface plasmons at 6.7eV, two dispersive peaks below the bulk plasmon peak are also observed. The first peak which is relatively sharp starts linearly from 1.5eV at q∼0 and levels off around 9eV at the zone boundary (q = 1. 55 Å-1) . This peak is due to the excitation of direct non-vertical interband transitions along the X-W-X direction of energy bands in Al. The second peak, broad and diffuse with energy higher than the first one, has approximately linear dispersion which extends beyond 12eV and shows no sign of leveling off at large q.
Development of a Field Emission Stem and its Application to Element Analysis
Authors: Nomura S. , Todokoro H. , Komoda T. 
Published: June 2020

The Scanning Transmission Electron Microscope (STEM) has made possible specimen observation with a number of advantages such as high signal collection efficiency. In addition, STEM also permits element analysis of micro-areas, when it is used in conjunction with X-ray and/or electron spectrometers. These advantages become more effective by using a high brightness electron gun.The authors have developed a field emission STEM. The schematic diagram of the instrument is shown in Fig. 1. Electrons emitted from the tungsten tip are focused on a specimen by one electro-static and two magnetic lenses. The field emission tip is surrounded by ion pumps, and the vacuum of the gun chamber is maintained at better than 5xlO-10torr.
A Liquid Helium Cryostat for a Superconducting Objective and Cold Stage
Authors: Worsham R. E. , Mann J. E. 
Published: June 2020

In the design of the 150 kV High-Coherence Column, it was considered essential that the specimen be in ultra-high vacuum at liquid helium temperature for minimum radiation damage. It followed that the simplest solution was to make the entire region about the specimen at liquid helium temperature and to make the objective lens with a superconducting winding.For mechanical rigidity, two things were considered essential. First, a strong support structure for the liquid helium vessel and the objective lens. Second, the use of no liquid nitrogen but rather the use of helium vapor cooling for the radiation shields, leads and supports. The drawing, fig. 1, shows the helium vessel, 9-1/2-inches diameter by 5-inches tall, surrounded by two concentric radiation shields. The entire assembly is rigidly supported on four posts one of which is shown. These posts consist of cylinders of epoxyglass (G-10) spacing the components between their different temperatures.
Practical Means for Enhancing the Contrast of Carbon Black Aggregates in Electron Micrographs for Quantitative Image Analysis,
Authors: Heckman F. A. , Connolly J. E. , Redman E. 
Published: June 2020

The first goal of the work described below was to investigate and establish means for producing ultra high quality photographic images for automated image analysis. This procedure was absolutely mandatory because no reliable quantitative automated image analysis can be done with images which are deficient in any one of a number of essential properties. The second goal was to achieve a high degree of reproducibility in preparing the image. In order to achieve these goals we set out to optimize our image characteristics heuristically.We have found that high contrast is the most important factor in attaining superior image quality in electron micrographs of carbon blacks. The individual factors which affect image contrast in electron micrographs have been discussed in the literature.
The High Intrinsic Creep Strength of Non-Stoichiometric Ni2Alti
Authors: Polvani R. S. , Strutt P. R. , Tzeng Wen-Shian 
Published: June 2020

It has been demonstrated (1) that the creep strength of the B2-type structure alloy NiAl (β-phase) can be enhanced to a remarkable degree by the addition of Ti which promotes the formation of the Heusler-type structure phase Ni2AlTi(β’). This phenomenon was attributed to the stabilization of dislocation networks at the semi-coherent (∼1%mismatch) phase interfaces. Now, recent observations are presented suggesting that this strengthening actually arises from the high intrinsic creep strength of the non-stoichiometric β and β’ phases.Fig. 1 shows creep strength at 1000°C as a function of Ti content for a series of alloys along the NiAl-Ni2AlTi tie-line; creep strength is defined as the stress to maintain a steady state rate of 10-7 sec-1. The phase regions along the tie-line were determined from precise lattice parameter measurements.
Changes In The Distribution And Morphology of γ' Precipitate In Neutron Irradiated Pe-16
Authors: Sklad P. S. , Bentley J. 
Published: June 2020

Nimonic PE-16 is a γ' hardened, austenitic alloy which has been chosen as a candidate for fuel element cladding and structural component applications in future breeder reactors due to its attractive high temperature strength properties and swelling resistance. The γ' phase is an ordered fee structure of LI2 symmetry having a Ni3(Al, Ti) composition, and is generally found as a finely distributed, spherical, coherent precipitate.Cylindrical (∽6 mm diam x ∽10 mm length) specimens were machined from rod and then solution treated at 1313 K for 2 hr followed by an aging treatment of 2 hr at 1073 K plus 16 hr at 973 K. Specimens were irradiated in the EBR-II at temperatures in the range 650 to 823 K and to fluences in the range 1.2 to 4.0 x 1026 n.m-2 (E >0.1 MeV). Details of the swelling and mechanical properties will be reported elsewhere.