bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology of Oligomer Crystals
Authors: Chen Y. T. , Bartkus E. A. 
Published: June 2020

Poly(ethylene terephthalate) (PET), contains approximately 1.5% oligomer (cyclic trimer). When films are heated the oligomers tend to migrate out and crystallize on the surface. The isolation and identification of oligomer has been reported; the crystal structure has been studied by x-ray and electron diffraction. Except for some optical work, however, the crystal morphology of oligomer has not been carefully studied. This paper gives some results of an electron-microscopy study of the morphology of oligomer crystals.PET films were annealed in an oven at different temperatures for different lengths of time. Oligomer crystals were observed after one hour of annealing at temperatures as low as 100°C; they became visible after only a few minutes of annealing at 200°C.
Photostimulated Exoelectron Emission from Slip Lines—A New Microscopy of Metal Deformation
Authors: Baxter William J. , Rouze Stanley R. 
Published: June 2020

Plastic deformation of metals enhances photoelectron emission, an effect known as photostimulated exoelectron emission. It has been proposed that the electrons are emitted from microcracks produced in the oxide. We have observed this phenomenon directly in a photoemission electron microscope (PEM) and shown conclusively that such emission does indeed originate from cracks in the oxide at slip lines.The PEM consists essentially of two magnetic and one electrostatic immersion lens. The sample is illuminated with ultraviolet radiation, and the photoemitted electrons are imaged on a fluorescent screen. A Channeltron Electron Multiplier Array provides image intensification. The sample is deformed in situ by bending to produce tensile deformation of the surface under study.
Characterization of Coherent, Ordered Precipitates in Nickel-Base Alloys
Authors: Kear B. H. , Oblak J. M. 
Published: June 2020

A nickel-base superalloy is essentially a Ni/Cr solid solution hardened by additions of Al (Ti, Nb, etc.) to precipitate a coherent, ordered phase. In most commercial alloy systems, e.g. B-1900, IN-100 and Mar-M200, the stable precipitate is Ni3 (Al,Ti) γ′, with an LI2structure. In A lloy 901 the normal precipitate is metastable Nis Ti3 γ′ ; the stable phase is a hexagonal Do2 4 structure. In Alloy 718 the strengthening precipitate is metastable γ″, which has a body-centered tetragonal D022 structure.Precipitate MorphologyIn most systems the ordered γ′ phase forms by a continuous precipitation re-action, which gives rise to a uniform intragranular dispersion of precipitate particles. For zero γ/γ′ misfit, the γ′ precipitates assume a spheroidal.
Microstructure of a CoCrNiTa Alloy System
Authors: Howe A. P. , Asgar K. , Bigelow W. C. 
Published: June 2020

The effect of tantalum additions to a 40-30-30 CoCrNi alloy has been studied by electron diffraction, transmission and scanning electron microscopy, and energy dispersive x-ray analysis in an attempt to identify the microstructure associated wit£ mechanical properties determined by a previous investigator.Samples were prepared by conventional investment casting techniques and thinned electrolytically in perchloric acid-ethanol solution at 20-35 volts for transmission electron microscopy. This solution also etched the surfaces of the specimens sufficiently to yield good sca ning electron micrographs.Energy dispersive k=ray analysis showed that the castings contain an average of 19% more Ta, 8% more Cr, 9% less Co and 6% less Ni than the weighed amounts.
A Study of Contrast For Biological Electron Microscopy
Authors: Chen C. S. 
Published: June 2020

The lack of contrast in the images of unstained and hydrated biological specimens is a serious limitation. Therefore, a quantitative study of contrast for various image modes has been undertaken. However, rather than perform time consuming experiments directly on the microscope, I have chosen to predict the contrast theoretically using a smaller number of experimental measurements to test the accuracy of the theoretical predictions.Fig. 1 shows the scattering distribution of carbon films at 100kV, and indicates that,at a given carbon thickness, the inelastic scattering passed by the aperture is almost ten times the elastic scattering. Thus, the image formed is incoherent, and highly chromatically aberrant. Due to the small elastic scattering, phase effects are expected to be small.
Ultrastructural Aspects of Sodium Transport in Rat Myometrium
Authors: Garfield R.E. , Daniel E.E. 
Published: June 2020

The energy-dependent formation of spherical membrane vesicles which serve as cation binding sites was originally proposed for tenia coli. More recently, membrane vesicles in rat myometrium have been postulated to serve as sites for an ATP-dependent, ouabain-insensitive system controlling cell volume as well as sites in which the classical Na+-K+-activated ATPase functions.In the present study, strips of rat myometrium were incubated in Krebs-Ringer solution at 25°C with and without various metabolic and transport inhibitors. Tissues were removed from the incubation solution at various times and analyzed for ATP, water and ion contents. Some pieces of tissue from the same uterine horns were prepared for the electron microscope for measurements of vesicle size and number.
Morphologic Changes of Rabbit Ovarian Follicles Following Copulation
Authors: Cherney David D. , DiDio Liberato J. A , Motta Pietro 
Published: June 2020

The interrelated processes enabling the ovum to be released from the mammalian ovary have been the subject of many investigations, which resulted in the advancement of several hypotheses; none, however, can as yet totally explain the morphophysiologic events leading to and responsible for ovulation.This investigation deals with a comprehensive light and electron microscopic study of the morphologic changes related to ovulation in the rabbit. Moreover, an attempt is made to establish a correlation between the modification of the follicle and perifollicular structures and their most likely causal factors.The morphology of the non-stimulated follicle is illustrated in Figure 1. Following copulation, follicles were removed at 2,4,6,8 and 10 hours, processed for electron microscopy, and comparable electron micrographs taken. As expected, the apex of the preovulatory follicle exhibited the most dramatic changes since it is the site where ovulation takes place.
Estrogen Stimulated Rhesus Monkey Oviducts in Organ Culture
Authors: Anderson Richard G. W. , Brenner Robert M. 
Published: June 2020

Work in this laboratory has established that oviducts of hypophysectomized or oophorectomized rhesus monkeys become atrophied and the epithelial surface becomes undifferentiated. Injections of these animals with 30 ng/day of estradiol benzoate stimulates the redifferentiation of the epithelial surface. After ten days of estrogen treatment, approximately 5% of the epithelial cells are ciliated and 50% are secretory. During ciliogenesis there is a series of complex changes which result in basal body replication and cilia formation. The stages of ciliogenesis are convenient markers for the effects of estrogen, as well as other drugs, on the oviduct.An organ culture system has been developed which can be used to study metabolic changes in the differentiating oviduct and to study ciliogenesis. The oviducts are removed from prepuberal or castrate monkeys which have received five days of estrogen treatment.
A Scanning Electron Microscopic Study of the Uriniferous Tubules
Authors: Andrews Peter M. 
Published: June 2020

Although there have been a number of recent scanning electron microscopic reports on the renal glomerulus, the advantages of scanning electron microscopy have not yet been applied to a systematic study of the uriniferous tubules. In the present investigation, scanning electron microscopy was used to study the ultrastructural morphology of the proximal, distal, thin loop, and collecting tubules. Material for observation was taken from rat kidneys which were fixed by vascular perfusion, sectioned by either cutting or fracturing technigues, and critically point dried.The brush border characterising proximal tubules is first detected on the luminal surface of Bowman's capsule adjacent to the urinary pole orifice. In this region one frequently finds irregular microvilli characterized by broad and flattened bases with occasional bulbous structures protruding from their surfaces.
Accuracy of linear polymer crystal structures determined from electron diffraction intensities: Problems with zonal data
Authors: Dorset Douglas L. 
Published: June 2020

In contrast to analyses based on X-ray and neutron diffraction intensity data, electron crystal structure determination for organic materials is only a crudely-developed procedure. Although the pioneering work of Vainshtein and co-workers has been very important for realization of the technique's advantages, self-consistent procedures based on earlier-derived diffraction theory have only recently emerged, enabling a reasonable estimate of what structural information might be obtained from a given microcrystalline organic specimen and how this might be best achieved. Problems which are unresolved include the optimal refinement procedure for an unknown structure and also the adequate identification of the correct crystal structure during this refinement process.The behavior of the crystallographic residual(R) during structure refinement is manifested by various minima in a multidimensional parameter space. The description of this space is more complicated for electron diffraction than for X-ray diffraction, although both cases include atomic position, atomic thermal vibration, atomic occupancy, “extinction”, and crystal distortion.
Microstructure investigation of initial formation of the Pd2Si-Si interface by TEM and ion channeling techniques
Authors: Yokota Y. , Wittimer M. , Ho P.S. 
Published: June 2020

Recent synchrotron-radiation experiment have established that the formation of the Schottky barrier at some transition metal-Si interface is essentially completed upon metal deposition of the first few monolayers. One problem of basic importance is the structural morphology and metal atom distribution of the initial silicide-Si interface. To complement our studies on the electronic and electrical characteristics, transmission electron microscopy (TEM), reflection electron microscopy (REM) and ion channeling techniques were used to investigate the microstructure of the initial Pd2Si-Si interface.Samples were prepared in UHV chember by e-beam evaporation of about 30-80 Å Pd on Si (100) or (111) substrates at room temperature then annealed at 200°C in various times to form Pd2Si. Back-etching of the Si substrates was finished with CP-4 solution. Samples were examined using a JEOL 200 CX microscope with TEM and REM mode.Fig. 1 is a high resolution lattice image of Pd2Si on (111) Si and a diffraction pattern. The amount of Pd deposited was estimated to be 80Å by ion back scattering
TEM studies of dark line defects in Fa1-xAlxAs heterostructures
Authors: Liliental Zuzanna 
Published: June 2020

Light-emitting diodes (LED's) are used as sources in fiber optical communication systems. They are required to exhibit high quantum efficiency and high reliability. But, in such devices, a degradation mechanism can take place. Non-radiative recombination occurs and dark line defects (DLD's) grow through the active layer and its surroundings. Such defects, observed in luminescence topographs have been reorganized from TEM observations as dislocation networks.Our recent investigations of the Ga1-xAlx As structure have shown that the defects (loops, dipoles, helical Dislocations) were not only present in the active layer, but a high density of them were observed in the window layer as well. These were mainly helical dislocations and loops which were created around precipitates. The window layer was doped with tellurium at concentrations of about (1-4)×1018/cm3. It is probable that at this concentration excess tellurium (or its compounds) were precipitated.
Characterization of precipitate morphology and composition in a Nb/V microalloyed steel
Authors: Newkirk J. W. , Hansen S. S. 
Published: June 2020

It is now well known that small additions of Nb, Ti or V can have a significant effect on the structure and properties of low-carbon steels. Appropriate control of composition and processing produces a refined ferrite grain size and a fine precipitate dispersion, the result being an outstanding combination of strength and toughness. These structural changes are both strongly influenced by the dissolution and re-precipitation of alloy carbonitrides during processing. Therefore, characterization of the precipitate morphology/composition in the final product is important in optimizing the design and processing of microalloyed steels.In this investigation, a control-rolled microalloyed steel was evaluated with a modern analytical electron microscope. Material was taken from 0.75-inch-thick plates with a nominal composition of 0.15C, 1.50Mn, 0.04Nb, 0.08V, 0.003Ti, 0.04A1 and 0.010N. Samples were prepared for extraction replicas by standard metallographic techniques, etched in 2% nital for about 30 seconds and then stripped with cellulose acetate. After backing with carbon, the replicas were placed on copper grids and the cellulose acetate dissolved.
Transverse microstructure of oxide formed on 20/25/Nb stainless steel
Authors: Bennett M.J. , Desport J.A. , Labun Patricia A. 
Published: June 2020

In the United Kingdom commercial advanced gas cooled nuclear power plants the fuel cladding is a 20% Cr/25% Ni/niobium stabilised (20/25/Nb) austenitic stainless steel and the coolant is carbon dioxide based. The oxidation behaviour of this steel has been studied extensively, e.g., with the main emphasis being directed to the oxidation kinetics and scale composition, as revealed by conventional surface analytical and X-ray diffraction techniques. This paper reports the first transmission electron microscopy undertaken on transverse sections through an oxide scale formed on this steel.The 20/25/Nb steel specimen was a coupon of rolled sheet, which had the composition given in Table. The surface of the steel was abraded on 600 grit SiC paper and subsequently was hydrogen annealed for 30 mins, at 930°C. Oxidation in carbon dioxide was continued for 4900h at 825°C (a probable maximum fuel cladding operating temperature). The magnitudes and kinetics of both oxidation and concurrent spallation have been reported. For the preparation of a TEM foil the oxide scale was protected and the oxide/gas interface was defined by a stainless steel coating deposited by sputter ion plating (SIP).
Application of convergent-beam electron diffraction to the detection of lattice parameter changes in hexagonal close-packed metals
Authors: Kohler V. L. , Shelton C. G. , Ralph Brian 
Published: June 2020

Convergent beam electron diffraction (CBED) patterns have been used in several different applications to materials problems (summarised by Steeds) and has more recently been used to quantify shifts in the lattice parameters of cubic materials (e.g. 2). This technique has proved highly sensitive to such changes, capable, via the use of very simple geometrical computer simulations, of the detection and quantification of changes in lattice parameters of hexagonal alloys.Alloy systems based on zinc and titanium were used. A simple geometrical computer simulation was used to quantify the shifts, ignoring dispersion surface effects, in the higher order Laue zone (HOLZ) lines upon change in the lattice parameters. X-ray diffraction data from each of the alloys was obtained to provide a standard for comparison. The sensitivity of each zone axis pattern to changes in either a or c was determined from the magnitude of the HOLZ line shifts in the CBED pattern.
Scattering-angle dependence of signal/background ratio of inner-shell electron excitation loss in EELS
Authors: Oikawa T. , Inoue M. , Honda T. , Kokubo Y. 
Published: June 2020

EELS allows us to make analysis of light elements such as hydrogen to heavy elements of microareas on the specimen. In energy loss spectra, however, elemental signals ride on a high background; therefore, the signal/background (S/B) ratio is very low in EELS. A technique which collects the center beam axial-symmetrically in the scattering angle is generally used to obtain high total intensity. However, the technique collects high background intensity together with elemental signals; therefore, the technique does not improve the S/B ratio. This report presents the experimental results of the S/B ratio measured as a function of the scattering angle and shows the possibility of the S/B ratio being improved in the high scattering angle range.Energy loss spectra have been measured using a JEM-200CX TEM with an energy analyzer ASEA3 at 200 kV.Fig.l shows a typical K-shell electron excitation edge riding on background in an energy loss spectrum.
Side bridge geometry after quick-freezing of stimulated and unstimulated frog skeletal muscle fibers
Authors: Sommer J.R. , Nassar R. , Walker S. 
Published: June 2020

Quick-freezing allows the structural analysis of timed perturbations of morphology. We are presenting preliminary results concerning the feasibility of studying directly the side bridge geometry of actin-myosin interactions within the time course of a twitch in single intact frog skeletal muscle fibers, both by freeze-substitution and freeze-fracture after quick-freezing, and following various time intervals between stimulation and impact of the fibers on a liquid He-cooled copper block.Materials and Methods. The quick-freezing device was a "Slammer"(Polaron) for which the electronics had been redesigned; they are capable, in combination with a Grass S48 stimulator, of any stimulation interval between 0 and 1 sec prior to freezing, including tetanus. The actual elapsed time between stimulation and freezing is recorded with a digital clock. Single intact tendonto- tendon frog skeletal muscle fibers (semitendinosus of r. temporaria) or toe muscle bundles (r.pipiens) were isolated by sharp dissection and placed between coextensive Pt stimulation wires on blackened 2% agarose, the height of which on the specimen holder was adjusted appropriately with respect to a spacer ring both, to calibrate the impact time and to prevent smashing of the fibers.
The morphology of the collecting system orifices in the normal human kidney
Authors: Gaines Joseph J. 
Published: June 2020

The renal collecting ducts empty via the ducts of Bellini into the area cribrosa of the renal papillae. The morphology of the orifices of the collecting duct emptying into the area cribrosa is of interest because of the relationship to intrarenal reflux and pylonephritic scarring. The purpose of this paper is to anatomically characterize these ductal orifices using scanning electron microscopy in the normal adult human kidney and to discuss possible pathological implications.Renal papillae were obtained from autopsy material of five normal adult human kidneys that were initially fixed in 10% buffered formalin. Three papillae were randomly selected from each kidney for a total of 15 papillae. The specimens were washed in distilled water, 0.5N hydrochloric acid, and again in distilled water. Surface debris were gently removed with a fine camel hair brush as needed. The samples were postfixed in osmium tetroxide, washed in distilled water, dehydrated in a graded series of ethanols, mounted on aluminum stubs, and sputter coated with gold-palladium. The specimens were examined in a JE0L JSM-35 scanning microscope at 25KV.
Cortical localization of a stage-specific surface glycoprotein and its polarization during early mouse development
Authors: Polak-Charcon S. , Johnson L. , Calarco-Gillam P. 
Published: June 2020

Stage-specific surface antigens synthesized and expressed during mouse preimplantation development have been detected by a rabbit antiserum prepared against mouse blastocysts (A-BL2). Serological and biochemical work showed the antigens (BL) were a glycoprotein doublet of 65-70,000 daltons expressed on the cell surface at the 4-cell stage, reaching a maximum on the 8-16 cell stage, and declining on the blastocyst. Synthesis and expression of BL occur although little classical RER or Golgi material are detectable. The present study utilized immunoelectron microscopy (IEM) and the peroxidase-antiperoxidase technique to determine the intracellular distribution of BL antigens and, potentially, their site of synthesis, and to follow BL antigen expression on the plasma membrane during early mouse development.Mouse embryos from unfertilized eggs to blastocysts were obtained as described. Some embryos were treated with pronase to remove the zona pellucida. Embryos were fixed 10 min in 0.05% gluteraldehyde in phosphate buffer (PB). Some embryos were permeabilized with saponin buffer for 30 min; some were not. All were incubated with either A-BL2 IgG or normal rabbit serum IgG (NRS), washed and incubated with HRP-conjugated goat anti-rabbit IgG.
Ultrastructural studies of the virions and paracrystalline inclusions in the skin tumor of molluscum contagiosum
Authors: Sun C.N. , Bowen W.R. , Watson J.H.L. 
Published: June 2020

Molluscum contagiosum is a benign tumor of human skin. Using light microscopy and TEM, early investigators demonstrated the presence of virions in the inclusion cells of these tumors. Recently a biopsy of a skin lesion with molluscum contagiosum on the forehead of an 84-year old patient was obtained. The present study, using epoxy embedments for TEM and critical point dried virus particles for SEM, clarifies some of the earlier observations and reports the presence of previously undescribed paracrystalline inclusions in the cytoplasm.The skin lesion consists of a localized and stratified proliferation of inclusion cells. Our studies were confined to the keratinous stratum. Numerous mature virions each approximately 250 nm in length and 150 nm in diameter, were present within the inclusion cells (Fig. 1,4). With SEM, each virion was found to be more oval-shaped than previously reported. Each virion had an electron-dense nucleoid core surrounded by an amorphous lateral body and an envelope.
Structural features of lymphocyte-stimulated mucopolysaccharide coats in human glioma-derived cells
Authors: Greenwood M.A. , Smith B.H. , Gately M.K. , Muul L. , McKeever P.E. 
Published: June 2020

As part of a series of studies of the properties of human glioma cells that contribute to their ability to escape cell-mediated immune attack (Gately et al.,(1982)we have examined the ultrastructural features of a protective mucopolysaccharide coat secreted by some of these brain tumor cell lines. This ruthenium red-positive coat or "halo" is formed or greatly increases in size in response to the presence of lymphocytes or a soluble factor released therefrom. It blocks the approach of cytotoxic lymphocytes to the tumor cells and hence tumor cell killing. Hyaluronidase appears to be a major structural component. The "halo" is destroyed by bovine testicular or streptomyces hyaluronidase, and chondritinase ABC.To determine the ultrastructural features of this halo we have examined 5 human glioma cell lines in vitro. These were derived from I Grade II and 4 Grade IV astrocytomas, specimens of which were removed at surgery. Glioma derived (1000 per Costar well) were plated along with the soluble coatstimulating lymphocyte factor. At 24 hours erythrocytes were added as coat indicator at 24 hours.