bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymer Morphology Revealed by Staining Techniques
Authors: Reimschuessel A. C. , Kramer V.
Published: June 2020

Staining techniques can be used for either the identification of different polymers or for the differentiation of specific morphological domains within a given polymer. To reveal morphological features in nylon 6, we choose a technique based upon diffusion of the staining agent into accessible regions of the polymer.

When a crystallizable polymer - such as nylon 6 - is cooled from the melt, lamellae form by chainfolding of the crystallizing long chain macromolecules. The regions between adjacent lamellae represent the less ordered amorphous domains into which stain can diffuse. In this process the lamellae will be “outlined” by the dense stain, giving rise to contrast comparable to that obtained by “negative” staining techniques.

If the cooling of the polymer melt proceeds relatively slowly - as in molding operations - the lamellae are usually arranged in a radial manner. This morphology is referred to as spherulitic.
Diffraction from Bent Crystals of Linear Polymers
Authors: Moss Barbara , Dorset Douglas L.
Published: June 2020

Single crystal electron diffraction studies of organic materials have indicated that the microcrystals are often elastically deformed. Using the model proposed by Cowley, kinematic intensities from a uniformly bent crystal may be simulated from a smeared-out Patterson function. Investigation of several published linear polymer structures shows great variation in the amount of bending present. α-Poly(3,3-bis(chloromethyl)oxacyclobutane), denoted BCMO, forms rigid crystals with no evidence of bending. Moreover as the electron beam is parallel to the short 4.78Å axis, the structure factors are insensitive to the degree of bend (Fig. 1). In contrast, poly(trimethylene terephthalate) crystallizes with 18.64Å axis along the beam direction. Inclusion of an 8° bend considerably improves the agreement factor; from R = 0.36 for the flat crystal to R = 0.25. Nigeran also forms microcrystals with a long crystallographic axis in the beam direction. The structure factors are consequently sensitive to bend (Fig. 2) and the experimental data show evidence of 2° bend. Additionally, the consideration of elastic deformation of the crystals often leads to more realistic values of the temperature factors.
Energy-Filtered, Double-Rocked Zone Axis Patterns
Authors: Higgs A. , Krivanek O. L.
Published: June 2020

Wide angle zone axis patterns (ZAPs) have been acquired by the rock-unrock method by Eades in a Philips 400 and by Tanaka et al. in a JEM 100CX. Tanaka et al. used one set of coils before the specimen for rocking and one after the specimen for unrocking. Although this was sufficient to make the beam stationary at the detector, it did not bring it back parallel to the optic axis. Eades used two sets of coils both before and after the specimen and achieved complete de-scanning as well as complete de-rocking.

When the ZAPs are to be energy filtered it is important that the beam enter the spectrometer on axis. We have therefore followed Eades' approach and used two sets of coils before the specimen (coils IA, IB) to rock the beam about a stationary point on the specimen (Fig. 1), and two sets of coils after the specimen (IIA, IIB) to de-rock the beam in a precisely reciprocal arrangement.
Crystal Structure Analysis of Cu-Zr Alloys by Convergent Beam Diffraction
Authors: Marshall A. F. , Steeds J. W. , Bouchet D. , Shinde S. L. , Walmsley R. G.
Published: June 2020

Convergent beam electron diffraction is a powerful technique for determining the crystal structure of a material in TEM. In this paper we have applied it to the study of the intermetallic phases in the Cu-rich end of the Cu-Zr system. These phases are highly ordered. Their composition and structure has been previously studied by microprobe and x-ray diffraction with sometimes conflicting results.

The crystalline phases were obtained by annealing amorphous sputter-deposited Cu-Zr. Specimens were thinned for TEM by ion milling and observed in a Philips EM 400. Due to the large unit cells involved, a small convergence angle of diffraction was used; however, the three-dimensional lattice and symmetry information of convergent beam microdiffraction patterns is still present. The results are as follows:

1) 21 at% Zr in Cu: annealed at 500°C for 5 hours. An intermetallic phase, Cu3.6Zr (21.7% Zr), space group P6/m has been proposed near this composition (2). The major phase of our annealed material was hexagonal with a point group determined as 6/m.
Asbestos Microdiffraction with a High-Voltage Electron Microscope
Authors: Webber S. , Green I. S. , Ratkowski A. J.
Published: June 2020

Conventional transmission electron microscopes (TEM) are the most commonly used analytical tools for positive identification and quantitation of asbestos in air and water samples. Selected-area electron diffraction (SAED), the accepted method of asbestos identification, often cannot yield identifiable diffraction patterns from chrysotile asbestos fibers smaller than 0.1-μm diameter. Beaman and Baker introduced microdiffraction for positive identification of 0.02-μm diameter chrysotile fibrils but this focused-beam technique is optimal only with strongly demagnifying triplecondenser TEM's.

The small wavelength of the electron beam generated by high-voltage electron microscopes (HVEM) has distinct advantages for diffraction studies. The Ewald sphere at l000kV is approximately four times larger than the sphere of a l00kV beam and consequently intersects and projects more widespread points from a given plane in the reciprocal lattice. Furthermore, the beam can penetrate thicker specimens than conventional TEM's. We have assessed the capability of a double-condenser 1200kV HVEM (AEI EM7) to identify asbestos by microdiffraction.
CBED Identification of Type 3CPyrrhotite in Coal Liquefaction Product
Authors: Liliental Z. , Carpenter R. W. , Pollack S.
Published: June 2020

Pyrrhotite is formed from iron pyrite inclusions contained in various coals during liquefaction processes conducted in high pressure, high temperature hydrogen. The basic structure of pyrrhotite (Fe1-xS, where x lies in the approximate range 0.1 to 0.2) is hexagonal NiAs type. However, pyrrhotite can exist in several polytypic forms. It has been suggested that pyrrhotites are catalytically active in coal liquefaction, and that the degree of catalytic activity depended on the pyrrhotite iron content. Pyrrhotite particles present in coal liquefaction reactor product have been examined by x-ray diffraction; the diffraction peaks were asymmetrically broadened by either stacking disorder, compositional variation or small particle size effect. High spatial resolution electron microdiffraction has been used to resolve some of the ambiguities in pyrrhotite structure that resulted from the averaging behaviour of x-ray diffraction. A short description of some of the results on these specimen materials is reported here.
CBED Evidence of Lattice Strain in RSR 197 Superalloy
Authors: Kersker M. , Aigeltinger E. A. , Hren J. J.
Published: June 2020

Convergent beam diffraction is becoming more widely used as more precise crystallographic techniques become necessary. Relative lattice parameter measurements, crystallographic orientations, and crystal structure determinations are only a few applications. Carpenter [1] has used the technique to determine the Burgers vector of a dislocation in Si from one CBED pattern. Other applications to strain measurements are immediately suggested. Unfortunately, the technique is not quantitative in highly irregular strain fields unless a correlation can be made between line broadening and local strain. This paper reports the use of CBED fine structures to measure the local strain fields between γ' precipitates in a Ni-base superalloy.

A Philips 400 with a FEG was used to make the strain measurements. This combination is ideal for crystallographic measurements since it has a focusable probe in the conventional TEM mode of the order of 100 Å. Using the shadow image technique, very sensitive beam placement and rapid tilting are also possible.
Nanolithography Using In-Situ Electron Beam Vaporization of Very Low Molecular Weight Resists
Authors: Isaacson M. , Muray A.
Published: June 2020

We have begun a program of investigation of the suitability of very low molecular weiqht materials as electron beam resists for the development of structures on the nanometer scale. With the advent of reliable field emission source technology, electron sources can be produced that have brightnesses several orders of magnitude greater than existing thermionic sources. Thus, nanoamp beam currents are attainble in subnanometer diameter electron probes. This means that as little as a 10 μsec exposure is needed to deposit a dose of 1 C/cm2 in a sample. It therefore becomes reasonable to explore the ultimate limits of 1ithography, since different materials can be studied that are not necessarily as radiation sensitive as the standard high molecular weight resists (e.g., PMMA).

Our explorations have centered on materials of molecular weight around 100 which could be readily vaporized under the action of the incident electron beam directly within an electron microscope ( 10-3 to 103 C/cm2). The initial pattern writing and development can then be done in one step.
An X-Ray “Laser” at Electron Microscope Voltages?
Authors: Spence J.C.H. , Cowley J. M.
Published: June 2020

There has been much recent interest in the study of channeling radiation (see (1) for a review). In particular, several workers have suggested the possibility of obtaining lasing action from this radiation. Channeling radiation arises in the Bloch wave picture from transitions between bound transverse states of the fast electron. The Dirac equation for the scattering of the fast electron separates into a Dirac equation for relativistic plane-wave states in the forward direction and a Schroedinger equation describing the transverse states. The Bloch wave excitation amplitudes can then be interpreted as occupation indicies and conditions of orientation and voltage found which produce a population inversion. Classically, at high energies the crystal periodicity can be neglected and the radiation treated as arising from an electron travelling at relativistic velocity in the forward direction through a crystal tunnel with the superimposed transverse motion of an harmonic oscillator. Lasing action is obtained as a result of downward transitions between transverse Bloch wave states induced by the photons these generate.
Electronmicrofcopic Analysis of a Cabbage Moth Virus
Authors: Mazzone H.M. , Engler W.F. , Wray G. , Gröner A. , Zerillo R. , Bahr G.F.
Published: June 2020

A nucleoplyhedrosis virus (NPV) has been isolated from the cabbage moth (Mamestra brassicae, Linnaeus), a serious pest insect, and bears promise of becoming an effective biological insecticide against its host. Our studies on this virus constitute part of an effort to support its approval as an insect control agent.

The NPVs are characterized by the presence of polyhedral inclusion bodies, containing rod shaped virus particles. When ingested by the host insect, the inclusion bodies are broken down in the gut. The released virus particles infect and multiply in the nuclei of susceptible cells. Viruses having these properties are representatives of the Baculoviruses, subgroup A.

The inclusion bodies of the cabbage moth NPV (Darmstadt strain) analyzed were approximately 1 - 2.3 um in diameter (Fig. 1). We used the HVEM to penetrate whole mount, naturally contrasted, airdried inclusion bodies to obtain their average mass value.
Use of TEM in Plant Disease Diagnosis: A Xylem-Limited Bacterium Associated with Diseased ‘Toronto’ Creeping Bentgrass
Authors: Baker Karen K. , Roberts David L.
Published: June 2020

Plant disease diagnosis is most often accomplished by examination of symptoms and observation or isolation of causal organisms. Occasionally, diseases of unknown etiology occur and are difficult or impossible to accurately diagnose by the usual means. In 1980, such a disease was observed on Agrostis palustris Huds. c.v. Toronto (creeping bentgrass) putting greens at the Butler National Golf Course in Oak Brook, IL.

The wilting symptoms of the disease and the irregular nature of its spread through affected areas suggested that an infectious agent was involved. However, normal isolation procedures did not yield any organism known to infect turf grass. TEM was employed in order to aid in the possible diagnosis of the disease.

Crown, root and leaf tissue of both infected and symptomless plants were fixed in cold 5% glutaraldehyde in 0.1 M phosphate buffer, post-fixed in buffered 1% osmium tetroxide, dehydrated in ethanol and embedded in a 1:1 mixture of Spurrs and epon-araldite epoxy resins.
Structural Role of rRNAs on the Ribosomal Subunits from E. Coli by Scanning Transmission Electron Microscopy
Authors: Boublik M. , Robakis N. , Wall J.S.
Published: June 2020

The three-dimensional structure and function of biological supramolecular complexes are, in general, determined and stabilized by conformation and interactions of their macromolecular components. In the case of ribosomes, it has been suggested that one of the functions of ribosomal RNAs is to act as a scaffold maintaining the shape of the ribosomal subunits. In order to investigate this question, we have conducted a comparative TEM and STEM study of the structure of the small 30S subunit of E. coli and its 16S RNA.

The conventional electron microscopic imaging of nucleic acids is performed by spreading them in the presence of protein or detergent; the particles are contrasted by electron dense solution (uranyl acetate) or by shadowing with metal (tungsten). By using the STEM on freeze-dried specimens we have avoided the shearing forces of the spreading, and minimized both the collapse of rRNA due to air drying and the loss of resolution due to staining or shadowing. Figure 1, is a conventional (TEM) electron micrograph of 30S E. coli subunits contrasted with uranyl acetate.
An Ultrastructural Study of Particulate Matter and Ferruginous Bodies in the Sputum from Former Asbestos Workers
Authors: Dodson Ronald F. , Glenn Williams M. , McLarty Jerry W. , Hurst George A.
Published: June 2020

Limited data exist concerning the ultrastructural assessment of the particulate content of sputum from occupationally exposed individuals. These assessments along with cytopathological screening provide valuable information about the current lung clearance patterns of these individuals.

Sputum samples were collected from nine former asbestos workers who were selected because their cytopathological history included the presence of ferruginous bodies. A portion of each sample not needed for cytopathologic screening was utilized in the present study. Some of this material was fixed, embedded, and sectioned for electron microscopy, while a separate portion of the material was digested and collected on a Nuclepore filter. Energy dispersive analysis was used in assessing inorganic matter in both preparations as well as defining the core composition of the ferruginous bodies.

The ultrastructural studies of the macrophage--ferruginous body interactions revealed abundant fibrillar elements (Fig. 1) in the subplasmalemmal zone of the macrophages. The extracellular boundary consisted of a halo of finegrained material separating the cell membrane from the dense ferruginous material.
Ultrasonically Induced Changes in Synapses
Authors: Borrelli M. J.
Published: June 2020

It had previously been demonstrated that controlled ultrasonic exposures of the mammalian central nervous system (CNS) produced reversible nerve potential suppression and irreversible limb paralysis. These functional effects appeared immediately after the exposures,but no abnormal morphology was detected with the light microscope for at least 10 min, and not all exposures resulting in functional changes produced observable altered morphology. It was therefore speculated that ultrasound produced its initial effects within the tissue ultrastructure,and that some post-exposure time was required before any changes attained dimensions observable with light microscopy.

Ultrasonically exposed CNS tissue has recently been examined with transmission electron microscopy and induced changes have been observed within 30 sec after the exposure. Adult female cats were anesthetized and placed in a stereotaxic unit. The animals were prepared for ultrasonic exposure of the brain as described by W. Fry and the common carotid arteries were cannulated.
Structural Variations Along the Length of Multiply Innervated Muscle Fibers in Rat Inferior Rectus—A Serial Analysis
Authors: Davidowitz J. , Chiarandini D. J. , Philips G. H. , Breinin G. M.
Published: June 2020

Morphological definitions of muscle fiber types have generally been based on the tacit assumption that the structure of a given fiber is essentially constant along it length. Recently, however, the serial sampling of rabbit extraocular muscle (EOM) has shown that some multiply innervated fibers (MIFs) display systematic variation of both the sarcoplasmic reticulum (SR) and mitochondrial content. The purpose of the present study was to determine whether systematically varying MIFs occur in rat EOM as well: such fibers had not been detected in previous studies of rat EOM by means of standard sampling methods. A young (175 gm) white Wistar rat was perfused with 2% paraformaldehyde-2% glutaraldehyde in phosphate buffer. The inferior rectus was removed intact, fixed in 4% glutaraldehyde, postfixed in 1% osmium tetroxide, dehydrated in graded ethanols, and embedded whole in Epon 812. The muscle was serially sectioned at 15u, and 114 1u sections and 42 ultrathin sections were recut from the original thick sections for sequential samplings.
Insights into the Secretory Pathway, the Mechanism of Terminal Glycosylation and Intracellular Peptide Hormone Receptors from Studies on Hepatic Golgi Fractions
Authors: Bergeron J.J.M. , Posner B.I. , Paiement Jacques , Sikstrom R. , Khan M.
Published: June 2020

Recent studies on purified subcellular fractions of hepatic Golgi apparatus have provided insight into the functioning of the Golgi apparatusin vivo.

The hepatocyte is the site of synthesis of most circulating plasma proteins. On a total protein basis, purified Golgi fractions revealed mainly secretory content (albumin, transferrin and other plasma proteins) as major constituents. After anin vivoinjection of radiolabeled leucine, newly synthesized secretory protein followed a temporal route fromcistotransregions of Golgi apparatus before appearance in the plasma. This route was revealed by studies on disrupted Golgi fractions enriched in disparate regions of the Golgi apparatus.

The terminal glycosylation of secretory glcyoproteins (e.g. transferrin) can be studied by observing the transfer of UDP-(3H)-galactose to endogenous acceptors within Golgi fractions. Transfer was shown to occur to a glycolipid (dolichyl galactosyl phosphate) probably on the cytosolic aspect of the Golgi membrane. Translocation of the labeled galactose across the membrane coincided with fusion of Golgi sacculesin vitro. It is felt that during the process of Golgi membrane fusion, inverted lipid- micellar membrane structures translocate the dolichyl galactosyl phosphate from a cytosolic to a luminal orientation. Luminally oriented dolichyl galactosyl phosphate would then serve as substrate for galactose transfer to intraluminal glycopeptide acceptors via intraluminal galactosyl transferase enzyme.
Ultrastructural Observations of Ovarian Ceroid Accumulation in Mice Exposed In Vitro to Diethylstilbestrol (DES)
Authors: Wordinger R. , Miller G.
Published: June 2020

Genetial tract abnormalities in female offspring have been reported in mice following prenatal exposure to diethylsti1bes- trol (DES). Some of these abnormalities may be ovarian-dependent since most offspring are in a persistant estrogenic state even at 12-18 months of age. Accumulation of ovarian ceroid after long-term estrogen exposure has been described by light microscopy. This study was designed to examine the ultrastructure of ceroid accumulation in ovaries of mice exposed prenatally to DES.

Virgin random bred Swiss mice 6-8 weeks old, were placed with individual males and examined daily for vaginal plugs. The presence of a vaginal plug was considered Day 0 of pregnancy. Pregnant mice were given a s.c. injection of DES (10μg/kg in 0.1.cc corn oil) or corn oil on Day 15 of gestation. All animals were allowed to give birth, and offspring were weaned at 4 weeks of age. Female offspring were housed in groups of 6 until 5 months of age and then sacrificed.
The Shadow Widths of Very Small Particles are Formed Independently of the Metal Cap Build Up on the Particle
Authors: Ruben George C.
Published: June 2020

The formation of shadows behind small particles has been thought to be a geometric process (GP) where the metal cap build up on the particle creates a shadow width the same size as or larger than the particle. This GP cannot explain why gold particle shadow widths are generally larger than the gold particle and may have no appreciable metal cap build up (fig. 1). Ruben and Telford have suggested that particle shadow widths are formed by the width dependent deflection of shadow metal (SM) lateral to and infront of the particle. The trajectory of the deflected SM is determined by the incoming shadow angle (45°). Since there can be up to 1.4 times (at 45°) more SM directly striking the particle than the film surface, a ridge of metal nuclei lateral to and infront of the particle can be formed. This ridge in turn can prevent some SM from directly landing in the metal free shadow area. However, the SM that does land in the shadow area (not blocked by the particle or its ridge) does not stick and apparently surface migrates into the SM film behind the particle.
Gastric Ulcers Produced by Cisplatin
Authors: Aggarwal S.K. , San Antonio J.
Published: June 2020

Cisplatin (cis-dichlorodiammineplatinum(II)) a potent antitumor agent is now available for the treatment of testicular and ovarian cancers. It is however, not free from its serious side effects including nephrotoxicity, gastro intestinal toxicity, myelosuppression, and ototoxicity. Here we now report that the drug produces peculiar bloating of the stomach in rats and induces acute ulceration.

Wistar-derived rats weighing 200-250 g were administered cisplatin(9 mg/kg) ip as a single dose in 0.15 M NaCl. After 3 days the animals were sacrificed by decapitation. The stomachs were removed, the contents analyzed for pepsin and acidity. The inner surface was examined with a dissecting microscope after a moderate stretching for ulcers. Affected areas were fixed and processed for routine electron microscopy and enzyme cytochemistry.

The drug treated animals kept on food and water consistently showed bloating and lesions (Fig. 1) with a frequency of 6-70 ulcers in the rumen section of the stomachs.
Cell Fine Structure as Revealed in Dessicator-Dried Resinless Sections
Authors: Becker R. P. , Wolosewick J. J. , Ross-Stanton J.
Published: June 2020

Methodology has been introduced recently which allows transmission and scanning electron microscopy of cell fine structure in semi-thin sections unencumbered by an embedding medium. Images obtained from these “resinless” sections show a three-dimensional lattice of microtrabeculfee contiguous with cytoskeletal structures and membrane-bounded cell organelles. Visualization of these structures, especially of the matiiDra-nous components, can be facilitated by employing tannic acid in the fixation step and dessicator drying, as reported here.

Albino rats were fixed by vascular perfusion with 2% glutaraldehyde or 1.5% depolymerized paraformaldehyde plus 2.5% glutaraldehyde in 0.1M sodium cacodylate (pH 7.4). Tissues were removed and minced in the fixative and stored overnight in fixative containing 4% tannic acid. The tissues were rinsed in buffer (0.2M cacodylate), exposed to 1% buffered osmium tetroxide, dehydrated in ethyl alcohol, and embedded in pure polyethylene glycol-6000 (PEG). Sections were cut on glass knives with a Sorvall MT-1 microtome and mounted onto poly-L-lysine, formvar-carbon coated grids while submerged in a solution of 95% ethanol containing 5% PEG.
Localization of Calcific Deposits in Aortic Valve Leaflets by Radiography, X-Ray Analysis, and Transmission Electron Microscopy
Authors: Colonna Kathryn N. , Breese Sydney S. , David Deck J.
Published: June 2020

Bioprosthetic heart valves composed of preserved tissue frequently calcify over a period of years after implantation in place of diseased natural valves. Recent experiments which implanted porcine aortic valves in young calves were followed less than four weeks later by beginning calcification of valve leaflets. To confirm, localize and measure the varying densities of calcific deposits, leaflet tissues were systematically examined by radiography, energy dispersive x-ray analysis and transmission electron microscopy.

Soft x-ray photography of recovered valves demonstrated tissue densities, presumably calcified sites, fanning into the leaflets from similarly dense areas of leaflet attachment to the aortic wall (Fig. 1). Regions of leaflets showing a range of densities were excised and critical-point dried for scanning electron microscopy and x-ray microanalysis. Samples from areas of unimplanted valves radiographically free of dense aggregations were excised and prepared similarly for controls. These specimens were examined by means of the scanning and x-ray modes of a JEOL-100 CX electron microscope with an attached KEVEX-7000 micrg-x-ray analyzer at 60 KEV and 300x magnification.
An Aldehyde/Hydrazide Polymerization Technique for Biological SEM Specimen Preparation
Authors: Gunning W. T. , Crang R. E.
Published: June 2020

Two water-soluble embedding techniques for transmission electron microscopy (TEM) utilizing the polymerization of glutaraldehyde were proposed in the early 1970's. Pease and Peterson introduced a glutaraldehyde-urea polymer medium and Heckman and Barrnett proposed a glutaraldehyde-carbohydrazide (GACH) medium. Both permitted the retention of lipids in tissues without the harsh extraction of cellular constituents by fixatives, organic dehydrators and embedding agents. These techniques were of limited application and yielded low contrast or negative-stained images in the TEM. This technique has not been previously considered as potentially useful for scanning electron microscopy (SEM) due to the covering and obliterating of surface morphology. Virtually all SEM techniques for biological and specimen preparation, aside from freeze-drying, replace or extract most of the native elemental compositions of cells and tissues. Freezing and freeze-drying techniques are cumbersome, time-consuming, may require elaborate equipment and can induce artifacts due to ice crystal formation. We propose a new approach of SEM sample preparation using modifications of the GACH technique employed in TEM.
Ions and Water in Cells and Tissues Studied by Microprobe Analysis of Frozen-Hydrated Sections in the SEM
Authors: Gupta Brij L. , Hall T. A.
Published: June 2020

Electrolyte elements including Na, K, Cl, Ca and Mg are increasingly implicated in a variety of cell and tissue functions. A proper understanding of their role requires knowledge of the distribution of these elements in and around cells at microscopic levels. There has been a lack of suitable methods to measure elemental concentrations in microvolumes in situ. The electron probe x-ray microanalysis (microprobe analysis) of frozen sections is proving effective in providing such data.

The total concentrations in subcompartments measured by microprobe analysis can be compared with the free concentrations and the activities measured by other methods such as microelectrodes to yield information on the possible binding or sequestration sites for the elements concerned.

Method. The technique of microprobe analysis of thick(>0.5 μm) frozen-hydrated sections in a scanning electron microscope column (SEM) was initiated and developed and has been applied in our laboratory to investigate a range of cellular transport processes.
Entry of Membrane Viruses into Animal Cells
Authors: Simons K. , Matlin K. , Reggio H. , Helenius A.
Published: June 2020

Recent work in this laboratory has shewn that Semliki Forest virus, an enveloped alphavirus, enters BHK-21 cells by adsorptive endocytosis in coated vesicles, and is routed via endosemes (prelysosomal vacuoles) into the lysoscmal compartment where the low pH induces a fusion reaction between the virus membrane and the lysoscmal mentorane.This fusion event introduces the virus nucleocapsid into the cytoplasm where virus replication commences.

We have now studied hew two other enveloped viruses, fowl plague virus (FPV), an influenza virus and vesicular stomatitis virus (VSV), a rhabdovirus, enter into MDCK-cells. FPV binds to sialic acid- containing receptors, mainly located on microvilli of the cell surface. The surface-bound virus is rapidly internalized through coated pits into coated vesicles which prcbably fuse with endosemes. From here the virus is routed into lysosomes. Biochemical assays shewed that surface-bound viruses are internalized with a half-life of 10-15 minutes. This is in the same range as previously described for Semliki Forest virus and physiological ligands internalized into the cell by receptor-mediated endocytosis.
Ferritin-Conjugated Antibody for the Demonstration of Isoantigens on the Surface of Murine Cells
Authors: Aoki T. , Izard J. , Hämmerling U. , de Harven E. , Old L. J.
Published: June 2020

Although a variety of viral and cellular antigens have been demonstrated by ferritin-labeled antibody, this technique has not been used to locate isoantigens on the surface of nucleated cells. The recognition of several systems of isoantigens on the surface of thymocytes, lymphocytes and leukemia cells of the mouse and the ease with which these cells can be obtained in free suspension led us to consider the ferritin-labelling method to determine the amount and location of these isoantigens on the cell surface. Because of the problems involved in the direct labelling of mouse gamma globulin by ferritin, we have chosen an indirect labelling technique (i.e. ferritin-conjugated rabbit anti mouse γG)to detect localization of mouse isoantibody.
The Ultrastructure of the Human Bronchial Submucosa
Authors: Brinkman G. L. , Brooks N. , Bryant V.
Published: June 2020

Up until now the only clinical interest in the human submucosa has centered around the hypertrophy of the mucous secreting glands in patients with chronic cough and sputum. Besides this function, the submucosa, which is a loose connective tissue, provides mechanical and functional support for the mucosa and also contains numerous cells whose contribution to bronchial physiology is not yet fully understood.

The mucosa is separated from the submucosa by the basement membrane, which is a thin, amorphous sheet between these two tissues. Auerbach has reported budding of the mucosal cells into the basement membrane in cigarette smoking dogs; a similar finding is shown in Figure 1 in a human cigarette smoker. Immediately beneath the basement membrane is a collection of reticular fibers which vary from being a thin layer of light density to a dense, thick layer of fibers. The reticular fibers are smaller, shorter and thinner than collagen fibers, and always single.
A Structural Element in the Envelope System of Vibrio Fetus
Authors: Ritchie A. E. , Bryner J. H.
Published: June 2020

In an earlier report (Ritchie, Keeler & Bryner. J. Gen, Microbiol. 43: 427 (1966) we noted that negatively-stained preparations of intact or ruptured Vibrio fetus cells failed to show evidence of a “regular geometrical pattern … in the envelope.” This was puzzling since the organism's envelope system was discernible in considerable detail in thin-section. This envelope system consists of a rugose integument and an underlying complex compartmentalized cytoplasmic membrane as illustrated in Fig. 1. Recently, we have observed small regions of orderly arrays of structural elements in cell fragments from phage-infected cultures. They appear to be subunits of a macromolecular complex associated with one of the component layers of the cell's envelope system. A cell fragment exhibiting one of these arrays is shown in Fig. 2 along with adhering phage. In this micrograph the large circular mass at the upper left is a flagellar basal granule indicating a polar origin of this fragment.
Triple Fixation For Electron Microscopy
Authors: Hayat M. A.
Published: June 2020

Potassium permanganate has been successfully employed to study membranous structures such as endoplasmic reticulum, Golgi, plastids, plasma membrane and myelin sheath. Since KMnO4 is a strong oxidizing agent, deposition of manganese or its oxides account for some of the observed contrast in the lipoprotein membranes, but a good deal of it is due to the removal of background proteins either by dehydration agents or by volatalization under the electron beam. Tissues fixed with KMnO4 exhibit somewhat granular structure because of the deposition of large clusters of stain molecules. The gross arrangement of membranes can also be modified. Since the aim of a good fixation technique is to preserve satisfactorily the cell as a whole and not the best preservation of only a small part of it, a combination of a mixture of glutaraldehyde and acrolein to obtain general preservation and KMnO4 to enhance contrast was employed to fix plant embryos, green algae and fungi.
Myocardial Alterations in Animals Following High Altitude Exposure
Authors: Bischoff M. B. , Dean W. D. , Bucci T. J. , Frics L . A.
Published: June 2020

There is a paucity of morphological evidence, particularly at the ultrastructural level, to correlate with tile physiological effects of chronic exposure to high altitude. In this study the myocardium of dogs and rabbits subjected to five months exposure at an altitude of 14,110 feet was compared to that of animals residing at sea level. The animals kept at 14,110 feet were shipped from sea level (160 feet) witnout acclimatization at intermediate altitudes.

The physiological parameters including the hematologic changes, pulmonary artery pressures, pulmonary artery oxygen saturations, electrocardiograph changes, right ventricular weight to body weight and right ventricular weight to total heart weight ratios observed in these animals have been reported previously.

The animals were necropsied at the end of the five months. The myocardium was quickly removed, cut into small pieces and immersed in 1% osmium tetroxide buffered with veronal acetate. Following fixation the tissues were dehydrated in ascending ethanol concentrations followed by propylene oxide and embedded in Epon 812. Ultrathin sections were doubly stained in uranyl acetate and lead citrate.
Bone Response to Beta-methasone and Cortisol
Authors: Dockum N. L. , Murphy D. B. , Jee W. S. S.
Published: June 2020

Analyses of undecalcified, decalcified, and plastic embedded bone specimens made by Jee following administration of Cortisol indicated a shift in the osteoclast versus osteoblast relationship with increased osteoclasts and a decrease in trabecular bone in the femur. Dockum and Jee reported daily injections of rats with 0.5 μCi of Pu239 for 3 to 7 days caused a shift in the osteoclast/osteoblast ratio increasing the number of osteoclasts to osteoblasts with a reduction in the amount of trabecular bone in the distal femur.

Berliner et al., found that fluocinolone acetonide elicited changes in fibroblasts, namely, dilation of endoplasmic reticulum with the appearance of intracellular dense bodies.

Fourteen six-week-old New Zealand white rabbits divided into two rabbits per group were given betamethasone in daily doses of 0.004, 0.012, 0.036, 0.100 and 0.300 mg/Kg of body weight for twenty days; one group received 1 mg/kg of Cortisol and one group served as controls.
The Morphology and Biochemistry of Isolated Skeletal Muscle Mitochondria
Authors: Dunn R. F. , Worsfold M. , Peter J. B.
Published: June 2020

This is a preliminary report on our studies correlating the morphology and biochemical characteristics of mitochondria isolated from rat skeletal muscle. Figures 1 to 3 show sections of the mitochondrial preparations made on two separate occasions. These were sedimented from low speed supernatants at 3,500 g for 10 minutes (Figs. 1 and 2) or from a 3,500 g supernatant sedimented at 7,000 g for 10 minutes (Fig. 3). Polarographic traces of the respiration of the 3,500 g fractions from the two preparations, with pyruvate and malate as substrates, are shown in Figure 4.

The mitochondria in the 70-3,500 g fraction from rat A (Fig. 1) were generally compact with closely packed cristae. Contamination with myofibrillar material was evident. In the 7,000 g fraction from the same animal, very few myofibrils were seen, and the mitochondria appeared distended and generally swollen (Fig. 3). The respiratory control ratio (RCR) of the 3,500 g mitochondria (Fig. 1) was 3.1 compared to 2.2 of the 7,000 g fraction (Fig. 3). Using our technique of preparation most of the mitochondria from rat skeletal muscle were sedimented at 3,500 g.
Ultrastructural Studies of Peripheral Nerves: Comparison of Regeneration to Normal Growth
Authors: Harkin James C. , Spurlock Ben O.
Published: June 2020

If a peripheral nerve is cut, Wallerian degeneration and regeneration occur. The severed nerve can regenerate a myelin sheath mimicking normal development, however in contrast to normal growth the injured nerve is repaired in part by a collagenous scar. A peripheral nerve has a complex structure. A nerve fascicle contains axons sheathed by Schwann cells and by endoneurium composed of collagen, basement membranes and other extracellular components. Each fascicle is encased in a perineurial sheath and a number of these fascicles are further enclosed by epineurium. In present studies developing, adult, and regenerating peripheral nerves were examined in tissue sections of Maraglas embedded specimens in a Philips EM-300 or Siemens Elmiskop I electron microscope.

In both normal and regenerating nerves the Schwann cell sheath is covered by a basement membrane. Schwann cells abut one another closely before axons traverse the gap between Schwann cells. Small axons appear earlier than large ones and non-myelinated before myelinated.
Correlation of Structure and Function in Canine Hearts
Authors: Mayfield E. D. , Thomas H. , Ghidoni J. J.
Published: June 2020

Correlation of ultrastructural and biochemical data concerning cellular organelles may play an important role in interpreting the effects of disease processes on tissues. This report concerns the biochemical and morphological parameters of cardiac muscle from 3 dog hearts. One dog was “normal” (118) and 2 dogs were clinically “dead” following complete tracheal obstruction; EKG and EEG recordings were isoelectric for 30 minutes. The hearts from both dead dogs were removed and perfused with oxygenated blood. In one instance (111) the blood was oxygenated by the attached lungs and in the other (116) the blood was oxygenated in a disc oxygenator. Both hearts resumed regular contraction; however, 116 fibrillated repeatedly during the 3-hour perfusion. All tissues were fixed in cold 5% cacodylate buffered (7.4) glutaraldehyde for 2 hours and postfixed in 2% OsO4 for 1 hour, dehydrated, and embedded in epoxy resin. Mitochondria were isolated in cold 0.18 M KCl, 10 mM EDTA (pH 7.2), and resuspended in the same media. Respiratory rates, respiratory control ratios, and P/O ratios were determined oxygraphically. Isolated mitochondria were fixed in 2% cacodylate buffered OsO4 and embedded in epoxy resin.
Erythrophagocytosis in the Liver in Hemolytic Anemias
Authors: Minick O. T. , Orfei E. , Volini F. , Kent G.
Published: June 2020

Hemolytic anemias were produced in rats by administering phenylhydrazine or anti-erythrocytic (rooster) serum, the latter having agglutinin and hemolysin titers exceeding 1:1000.

Following administration of phenylhydrazine, the erythrocytes undergo oxidative damage and are removed from the circulation by the cells of the reticulo-endothelial system, predominantly by the spleen. With increasing dosage or if animals are splenectomized, the Kupffer cells become an important site of sequestration and are greatly hypertrophied. Whole red cells are the most common type engulfed; they are broken down in digestive vacuoles, as shown by the presence of acid phosphatase activity (Fig. 1). Heinz body material and membranes persist longer than native hemoglobin. With larger doses of phenylhydrazine, erythrocytes undergo intravascular fragmentation, and the particles phagocytized are now mainly red cell fragments of varying sizes (Fig. 2).
Techniques Involved in the Acquisition of Serial Sections of the Atrioventricular Node for Light and Electron Microscopy
Authors: Emmett Sheila S. , Thaemert J. C.
Published: June 2020

The acquisition of serial sections of the atrioventricular node for light and electron microscopy is a formidable task. Ordinary techniques are not adequate if the best possible results are to be achieved at the electron microscopic level. The techniques outlined below have proven to be valuable in locating and determining the position of the AV node.

Whole hearts of 2-week old mice were fixed, in situ, by perfusion with 1% phosphate-buffered osmium tetroxide. The hearts were removed from the animals, sectioned transversely into 3 slices approximately equal in thickness, dehydrated in graded concentrations of ethanol and embedded in Epon 812. The block faces were trimmed to a trapezoidal shape ranging in size from 0.75 x 1 mm to 4 x 5 mm. Serial sections approximately 2 microns in thickness were cut with glass knives on a Porter-Blum MT-2 Ultramicrotome. While floating on a drop of water on the knife, each section was stretched with 1 drop of a 1:1, xylene in chloroform mixture applied directly to the section. The sections were picked up individually with a brush, transferred to a glass slide and oven dried for several hours prior to staining.
Deformation Twins in Drawn Aluminum - 0.9% Magnesium Wire
Authors: Dexter S. C. , Greenfield I. G.
Published: June 2020

A number of mechanisms have been suggested for the formation of the duplex <111> + <100> fiber texture in drawn wires of face centered cubic metals. Ahlborn and Wassermann proposed that mechanical twinning and subsequent twin rotation are responsible for this type of texture. They theorize that during deformation a <111> direction in each grain becomes aligned parallel to the wire axis, and that mechanical twins form in this matrix with the <511> twin direction also parallel to the wire axis. Upon further deformation, the <100> twin direction which is about 19.5 degrees from the wire axis rotates and approaches the wire axis.

Twins of this type and in a range of orientations corresponding to the rotation postulated were observed directly in drawn wires of Al - 0.9% Mg by transmission electron microscopy. The wires were cold drawn 96% to a final diameter of 0.038 inches. Longitudinal thin foils were prepared for electron microscopy in a two step process.
The Development of Voids in Nickel During Irradiation
Authors: Mastel B. , Brimhall J. L.
Published: June 2020

Voids have recently been reported in stainless steel after irradiation to a high fast fluence (> 1022 n/cm2) at elevated temperatures. The presence of these voids was attributed to the high vacancy concentration resulting from the irradiation. In this paper we wish to report the formation of voids in high purity nickel after a relatively low exposure to neutrons.

Nickel foil, 99-997% pure, in the form of disks 14 mm in diameter and 75μ thick was annealed at 700°C for one hour prior to irradiation. Irradiations were performed under two conditions: 1) in a NaK filled capsule equipped with thermocouples and a heater at a temperature of 400°C and 2) in a helium filled capsule at a calculated temperature of 400-450°C. Total neutron fluences were determined from flux wires and were 5 x 1019 n/cm2 and 4 x 1019n/cm2 (E > 1 MeV), respectively.
Practical High Resolution Microscopy
Authors: Marsh P. A. , Mullens T. , Price D.
Published: June 2020

It is possible to exceed the guaranteed resolution on most electron microscopes by careful attention to microscope parameters essential for high resolution work. While our experience is related to a Philips EM-200, we hope that some of these comments will apply to all electron microscopes.

The first considerations are vibration and magnetic fields. These are usually measured at the pre-installation survey and must be within specifications. It has been our experience, however, that these factors can be greatly influenced by the new facilities and therefore must be rechecked after the installation is completed. The relationship between the resolving power of an EM-200 and the maximum tolerable low frequency interference fields in milli-Oerstedt is 10 Å - 1.9, 8 Å - 1.4, 6 Å - 0.8.
An X-Ray Spectrometer Attachment for the Philips EM-200/EM-300 Electron Microscopes
Authors: Ogilvie R. E. , Moll S. H. , Schippert M. A.
Published: June 2020

An X-ray spectrometer has been developed to extend the analytical capability of the Philips EM-200/EM-300 Electron Microscopes to studies of sample chemistry. It attaches directly to the objective aperture port of the rotating/tilting specimen stage.

Shown in Figure 1, the spectrometer is a high resolution instrument, employing a mica crystal which is continuously curved to fulfill the X-ray focusing conditions over the entire angular range. Equipped with a flow proportional counter, it is capable of analyzing characteristic X-ray lines of any element from Na through U. With the rotating/tilting specimen stage and a replacement aperture installed in the microscope, the spectrometer may be attached to or removed from the instrument in less than five minutes. It may also be left in situ during normal use of the microscope.

Supplementing the present ability of the electron microscope to investigate morphology and crystal structure (by electron diffraction), the spectrometer allows the simultaneous determination of chemical composition by microprobe X-ray fluorescence analysis of areas approximately one micron in diameter.
“High Resolution High Voltage Electron Microscopy”
Authors: Siegel Benjamin M.
Published: June 2020

The potential advantages of high voltage electron microscopy for extending the limits of resolution and contrast in imaging low contrast objects, such as biomolecular specimens, is very great. The results of computations will be presented showing that at accelerating voltages of 500-1000 kV it should be possible to achieve spacial resolutions of 1 to 1.5 Å and using phase contrast imaging achieve adequate image contrast to observe single atoms of low atomic number.

The practical problems associated with the design and utilization of the high voltage instrument are, optimistically, within the range of competence of the state of the art. However, there are some extremely important and critical areas to be systematically investigated before we have achieved this competence. The basic electron optics of the column required is well understood, but before the full potential of an instrument capable of resolutions of better than 1.5 Å are realized some very careful development work will be required. Of great importance for the actual achievement of high resolution with a high voltage electron microscope is the fundamental limitation set by the characteristics of the high voltage electron beam that can be obtained from the accelerator column.