bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of Intranuclear Round Bodies of Enta-Moeba Histolytica After Dnasa and Rnasa Treatment
Authors: Gonzàlez Angulo A. , Ruiz de Chàvez I. , Treviño N. 
Published: June 2020

Recent morphological studies of E. histolytica have revealed the presence of several intranuclear structures which are clearly distinguished from other nuclear components. These are round membrane bound bodies of variable marked electron density averaging from 15 to 40 milimicra in diameter (Fig. 1). Their intranuclear location and persistance within the nucleus along the various stages of the life cycle of E. histolytica seems to indicate that these structures may have a functional role in the nucleus. The present study was undertaken to determine the existence of DNA and RNA in this intranuclear structures.Trophozoites of E. histolytica ABRM strains obtained from monoxenic cultures were fixed for 35 minutes in 2.5% Glutaraldehyde, 0.1M sodium cacodilate buffer.
Eye Pigment Granule Ultrastructure in Drosophila Melanogaster
Authors: Sun Donald C. , Crang Richard E. 
Published: June 2020

The compound eyes of wild type Drosophila melanogaster normally contain two pigments—ommochrome (brown) and drosopterine (red). However, sepiapterine (yellow), which is a biochemical precursor of drosopterine, is present in several mutant flies instead of drosopterine—or in addition to it. Transmission electron microscope observations reported here reveal fine structural differences between the pigment granules at various times post-pupation in D. melanogaster wild type as well as the mutants sepia and clot.Eyes from pupae at 54, 72 and 90 hours post-pupation were fixed with glutaraldehyde and osmium tetroxide followed by dehydration and embedment in Epon 812. Alternate thin (50-70 nm) and thick (1-2 μ) sections from the embedded material were sectioned with an ultramicrotome for electron and light microscopy respectively.
The Effects of Puromycin on the Ultrastructure of the Golgi Complex
Authors: Sturgess J. M. , Moscarello M. A. 
Published: June 2020

The most extensively studied site of action of puromycin is the ribosome where puromycin detaches nascent peptide chains, inhibiting protein synthesis. Ultrastructural and biochemical studies have shown the puromycin causes disaggregation of polyribosomes, accompanied by disorganisation of rough endoplasmic reticulum. Vacuolisation and regression of the Golgi complex have been reported in the Golgi complex after puromycin treatment in various cell types including liver, pancreas, thyroid and intestinal cells. Previous studies have not described details either of the sequence of changes in the Golgi complex or the reversal of changes after puromycin.In this study, the effects of puromycin have been evaluated in Golgi membranes isolated from rat liver by differential centrifugation. Isolated membranes have been examined in the electron microscope by negative staining with phosphotungstic acid and in ultrathin sections.
Evidence of Hormone Induction of Milk Proteins in Normal and Malignant Mammary Gland Cultures
Authors: McCarty Kenneth S. , Jones Richard F. , Nixon Jon C. , McCarty Kenneth S. 
Published: June 2020

Normal epithelial cells from mammary glands of mature virgin mice synthesize increasing levels of casein and α-lactalbumin when cultured in the presence of insulin, hydrocortisone, and prolactin. in the absence of DNA synthesis or when DNA synthesis is blocked, the augmentation of milk protein production does not occur. It would appear that a necessary coupling of secretory protein production to DNA synthesis or mitosis or both is essential.Mammary tissue from 10-12 day pregnant nulliparous C3H mice, BA type mammary adenocarcinoma, and H2712 type mammary adenocarcinoma have been compared in their response to insulin, dexamethasone and prolactin in organ and tissue cultures.
Electron Microscopy of Bacterial-Like Microorganisms From the Antarctic Soil
Authors: Uydess Ian , Vishniac Wolf 
Published: June 2020

Recently, a number of soil samples isolated from geographically distinct regions in the Asgard Range-Vanda Lake area of the Antarctic, were shown to contain living microorganisms which displayed bacterial-like morphologies. The microorganisms isolated from these samples were observed to have heterogeneous structural characteristics ranging from those with “typical” Gram - or Gram + morphologies, to those with “unique” morphologies which may be intermediate to the eubacteria and lower algae.Cell pellets prepared from the various soil samples were rinsed in phosphate buffered saline and fixed in Dalton's Chrome Osmium. These were then post-fixed in aqueous Uranyl Acetate, dehydrated in a graded alcohol series, and then embedded in Epon for electron microscopy. Examination of these preparations revealed the existence of several distinct morphologic types of bacterial-like microorganisms.
A Report Of Morphologically Aberrant Virus Particles in Cells Infected With MSV (FelLV) Virus
Authors: Al-Adhami R. A. , Chapman A. L. 
Published: June 2020

Fujinaga et al reported MSV induced rat and hamster osteosarcoma which showed an occassional unusual bud in the rat induced tumors. Savage and Hackett and Hackett and Sylvester reported abnormal type C virus in UCLB cells derived from Balb/3t3 cells infected and transformed with MLV. They wer unable to demonstrate sarcoma virus activity. Fischinger and O‘Connor reported the infection of cat embryo cells by a centrifugally induced aggregate of murine sarcoma virus and feline leukemia virus designated as MSV(FelLV). This virus gave rise to a defective, focus forming virus which propagated in cat cells but not in mouse cells.In the present study the morphoiogy of the MSV(FelLV) virus obtained from Dr. Fischinger and maintained in our laboratory since 1970 will be reported. Feline embryo fibroblasts (established in our lab.) and Crandall feline kidney cells (Cutter-Haver-Lockhart, Shawnee, Kansas) were used in this study.
Studies of Circular DNA Using a New Electron Microscopic Technique
Authors: Gordon C. N. 
Published: June 2020

Gordon and Kleinschmidt have described a new preparative technique for visualizing DNA by electron microscopy. This procedure, which is a modification of Hall's “mica substrate technique”, consists of the following steps: (a) K+ions on the cleavage surface of native mica are exchanged for Al3+ions by ion exchange. (b) The mica, with Al3+ in the exchange sites on the surface, is placed in a dilute aqueous salt solution of DNA for several minutes; during this period DNA becomes adsorbed on the surface. (c) The mica with adsorbed DNA is removed from the DNA solution, rinsed, dried and visualized for transmission electron microscopy by Hall's platinum pre-shadow replica technique.In previous studies of circular DNA by this technique, most of the molecules seen were either broken to linears or extensively tangled; in general, it was not possible to obtain suitably large samples of open extended molecules for contour length measurements.
Studies of Aggregates of Two Muscle Proteins with Scanning Transmission and Conventional Transmission Electron Microscopy
Authors: Lamvik M. K. , Isaacson M. S. , Crewe A. V. 
Published: June 2020

Studies of the structures of various aggregates of proteins from vertebrate striated muscle have begun, using in particular the scanning transmission electron microscope (STEM). The high collection efficiency of this microscope has been noted elsewhere and the contrast advantage and signal selection capabilities have been demonstrated.Although the instrument can produce high contrast images of unstained and unfixed biological material, it is not clear which preparation methods might maintain the native structure of such material. So the study begins on familiar ground with conventionl negatively stained preparations, While later steps will include less conventional methods.Rabbit tropomyosin Mg-tactoids in suspension were received from Dr. Carolyn Cohen (of Children's Cancer Research Foundation, Boston). The tactoids have a primary periodicity of 395 Å. Isolated myofibrils were obtained from Joseph Etlinger (of this University); myosin was extracted from them by a method similar to that of Dow and Stracher.
Tissue Structures in Frozen Sections
Authors: Tokuyasu K. T. , Singer S. J. 
Published: June 2020

When tissue pieces or isolated cells are fixed with glutaraldehyde, infused with 0.6 to 1.6 M sucrose solutions, frozen in liquid N2 and ultra-thin sectioned at -50 to 90°C, they show an excellent sectioning consistency. The frozen sections can be picked up from the knife edge with a droplet of a near saturated sucrose solution, and removed to room temperature. The sections then melt and spread on the droplet, and are transferred to coated grids and are then stained.Tissue preparations fixed only with glutaraldehyde are expected to be superior to conventional preparations, which involve OsO-fixation, dehydration with chemical solvent and embedding in plastic, in the preservation of lipid and protein conformations and, therefore, in the observation of tissue structures at the molecular level.
Spermiogenesis in the Nine-Banded Armadillo
Authors: Weaker Frank J. 
Published: June 2020

The testes of mature armadillos were fixed by either perfusion or immersion. The morphology of the seminiferous tubules and the process of spermiogenesis were studied.The developing spermatids are generally oval in shape and contain a centrally placed nucleus. A well-developed Golgi apparatus, scattered mitochondria, centrioles, smooth endoplasmic reticulum, and a chromatoid body are observed within the cytoplasm. Granules formed within the Golgi appear to coalesce to form the acrosomal granule, which is enclosed within a vesicle (Fi,g. 1). The acrosome adheres to the nucleus at the anterior pole of the developing spermatid. The acrosome vesicle collapses and extends over the anterior two-thirds of the nucleus (Fig. 2). As this vesicle expands, the Golgi continues to release granules into the vesicle. Concomitant with acrosome formation, the centrioles and chromatoid body migrate to the posterior pole of the developing cell.
Contribution of Ruthenium Chloride to the Ultracytochemical Study of Cerebellar Cortex
Authors: Castejón Orlando J. , Castejón Haydée V. , Viloría Maria E. , Rivero Indalecio 
Published: June 2020

Ruthenium Red has been utilized for the histochemical demonstration of acid mucopolysaccharides (Luft, 1971 a,b). In the present study a related compound ruthenium chloride has been applied to the study of cerebellar cortex in an attempt to evaluate its staining properties and potential value as a histochemical reagent for the demonstra tion of acid glycosaminoglycans.Albino mice were perfused with a mixture of glutaraldehyde-cacodylate sucrose buffer solution, pH 7.4 to which 0.1% ruthenium chloride was added. After perfusion the cerebellar cortex was sectioned in small blocks which were fixed by immersion in a fresh similar mixture and secondarily immersed in a 0.5% osmium tetroxide-cacody-late sucrose buffer with addition of 0.05% ruthenium chloride. Ultrathin sections were stained by uranyl acetate and lead citrate. Cerebellar cortex fixed only in glutaralde-hyde and stained with uranyl and lead salts were used as controls.
Ultrastructure of Mitotic Cells in Paraganglia of the Syrian Hamster
Authors: Mascorro Joe A. , Yates Robert D. 
Published: June 2020

Extra-adrenal chromaffin tissue classified as paraganglia is said to exert its greatest influence during prenatal life while the adrenal medulla is still largely undifferentiated. Various reports indicate that the majority of paraganglionic tissue in the mouse, rat, guinea pig and human involutes rapidly following birth, at which time the adrenal medulla and sympathetic nervous system come into prominence. Ultrastructural observations of hamster abdominal paraganglia have shown that this tissue is precocious, and it is interesting to note that mitotic cells are observed in these organs of neuroectodermal origin.Syrian hamsters 13 days of age or less were perfused with 3% glutaraldehyde buffered with 0.2M phosphate to pH 7.1-7.2.
Quantitative Immunocytochemistry of Corticotropin by the Unlabeled Antibody Enzyme Method with and without Peroxidase-Antiperoxidase Complex (PAP)
Authors: Petrali John P. , Moriarty Gwen C. , Sternberger Ludwig A. 
Published: June 2020

The unlabeled antibody enzyme method localizes antigen by reaction with (1) specific antiserum (primary antibodies), (2) antiserum to the primary immunoglobulin, (3) antiperoxidase (anti-PO) and (4) peroxidase (P0). The reaction is developed with hydrogen peroxide as substrate for P0 and diaminobenzidine (DAB) as co-substrate, followed by osmication. Anti-PO can be used in the form of antiserum (procedure A), purified antibody (procedure B), or steps (3) and (4) can be combined by the use of purified, soluble PAP (procedure C). Only at relatively low resolutions does identification of antigen depend on specific staining. High resolution localization depends on identification of the characteristic ring-shaped PAP molecules (Fig. 1).We have compared the sensitivities of procedures A, B and C upon staining serial Araldite sections of rat pituitary intermediate lobes using anti17-39 corticotropin as primary antiserum. PAP contained 3.33 mg anti-PO, 1.2 mg PO/ml and was essentially pure. It was employed at a standard dilution of 1:50. Antiserum and purified antibody to PO were used at standard dilutions containing equivalent amounts of anti-PO (1:24 for antiserum, 1:5 for purified antibody).
High-resolution microscopy of a GTB-type Rb-Nb-oxide
Authors: Olsen A. , McLean J.D. , Goodman P. 
Published: June 2020

Synthesis of specific tunnel compounds has recently been stimulated by their potential application in both cation storage and ionic conductor technologies. However, the theoretical understanding of these compounds is insufficient to be predictive about the tunnel retentivity for various cations. At present HREM seems to be the most practical method of examining this experimentally when, as in the present case, several different types of tunnels are competing for the available cations.A new type of structure in the Rb-Nb-O system, named GTB by Bhide and Gasperin, was first analysed by Gatehouse et al using single crystal x-ray diffraction. It was found to have the tetragonal framework structure indicated schematically in Figure 1, in which corner-linked NbO6 octahedra form 4, 5, 6 and 7-sided tunnels. A similar structure was later found by Bhide and Gasperin in the Tl-Nb-O system. The cell dimensions of the Rb-compound are: a = 27.49 Å; c = 3.96 Å. The composition of the framework is Nb54O146.
Domain structures in PbZr0.95 Ti0.05O3
Authors: Kuroda K. , Heuer A. H. 
Published: June 2020

Lead zirconate titenate (Pb(Zr,Ti)O3, PZT) is a well known piezoelectric substance. Three phases have been reported in modified PbZr0.95Ti0.05O3 (PZT 95/5) bodies -- a low temperature rhombohedral ferroelectric phase (FR1), a high temperature rhombohedral ferroelectric phase (FR2) and a cubic paraelectric phase (PC). A pressure induced ferroelectric to antiferroelectric phase transformation has also been reported in modified PZT 95/5 ceramics. These phase transformations are of technological importance, as this ceramic has practical applications as a power source in which large quantities of charge are released by shock wave depolarization.Both as-fired and pressure de-poled samples of PZT 95/5 ceramics with 0.8% Nb were investigated by transmission electron microscopy. Specimens for electron microscopical study were prepared from thin sections, which had been sliced by diamond saw and then mechanically polished with 600 grit SiC paper followed by diamond polishing to about 100 μm thickness. These specimens were then argon ion milled to electron transparency; a liquid N2 cooled stage was used to try and prevent the occurrence of phase transformations due to heating during ion beam thinning. Special care was also taken to minimize beam heating during electron microscopical observation.
Analytical electron microscopy of TiB2 implanted with 1 MeV nickel
Authors: Sklad P. S. , Anqelini P. , Lewis M. B. , Houston J. T. , McHargue C. J. 
Published: June 2020

Recently a series of studies has been undertaken to determine the effect of ion implantation on the properties of structural ceramics. In the technique energetic ions impinge on the surface of the material displacing atoms, creating various types of point defects, and finally come to rest in the near-surface region. Because of the nature of these processes it is possible to introduce an element into the substrate to a concentration level much higher than normal equilibrium would allow. The present study is concerned with the microstructure produced by implanting TiB2 with 1 MeV nickel ions.Polycrystalline samples of TiB2 were implanted at ambient temperatures with 1 MeV Ni+ ions to a fluence of 1 × 1017 ions/cm2. The implanted samples were cut into pieces approximately 1 mm × 2 mm × 5 mm and pairs were glued together with the implanted surfaces facing each other. Slices ∼250 μm thick were then cut, mechanically polished to ∼75 μm, mounted on copper washers, and argon ion milled. This procedure allowed examination of the implanted layer in cross section. The TEM specimens were then examined in a JEM 120CX equipped with a Kevex 5100 x-ray energy dispersive spectroscopy (EDS) system interfaced to a PDP-11/34 computer and peripherals.
Scanning electron beam lithography
Authors: Broers Alec N. 
Published: June 2020

This paper discusses the role of scanning electron beam lithography in semiconductor microcircuit production and in the experimental fabrication of devices in the laboratory. It also describes the electron optical equipment developed for these applications.Electron beam lithography has found an important place in integrated circuit production through its ability to produce structures without masks, rather than because it can produce high resolution. Resolution, however, has been important in research and development where electron beams have been used to produce smaller devices than any other method. Many early micron and sub-micron large scale integration devices were built first with electron beams, and structures as small as a few tens of nanometers have been made for electrical characterization.Optical methods are generally more economical than electron beams for the routine production of microcircuits because exposure rates are higher and system costs are lower. Resolution with optical lithography is adequate for all devices likely to be in production in the next few years (minimum linewidth 0.75μ - 2μ) so electron beams at present only offer an advantage in fabricating masks, or in exposing customized wafers where masks are not replicated a sufficiently large number of times to offset their cost.
Electron beam resist systems: A critical review of recent developments
Authors: Watts M.P.C. 
Published: June 2020

The aim of this paper is to critically review the latest commercial and scientific resist developments in the light of the needs of the semiconductor industry in direct write applications. These needs can be expressed as a set of usable ranges for sensitivity, resolution, and process compatibility, most notably dry etch resistance. The resist sensitivity needed for tolerable throughput varies from 0.5uCoul/cm2to 20 uCoul/cm2depending on the machine being used. Submicron resolution is now a necessity (0.1-1.0 um) because circuits with 1-2 um features are being made using optical lithography.The resolution limit of a resist is difficult to measure because resolution depends critically on the “image quality” (beam size/shape). Furthermore, for a given critical dimension to be used in a VLSI Si process, that dimension must be reproducible to within tight statistical limits, eg., for Hewlett-Packard's NMOS process the requirement is 1.5um lines, 1um spaces with a 3σ of +/− 0.25um (99.9% confidence limit). With these caveats, SEM's of resolution test paterns can be used as a guide to working resolution.
Reflection electron microscopy (REM) observation of monatomic steps and <133> steps of GaAs(110) surfaces
Authors: Hsu Tung 
Published: June 2020

Previous REM observations of atomic steps have shown that higher steps on crystal surfaces produce stronger contrast in REM images. Also observed with REM method was that a screw dislocation can be identified by a terminating step and a strong strain field contrast. Other methods have concluded that for the GaAs(110) surface, both monatomic steps withheight (where a is the lattice constant or 5.65Å) and steps of twice that height arepossible.A step that ends at a screw dislocation must be ofhigh, corresponding to one unit cell in the (110) direction. Consequently, astep must show lighter contrast than the one that ends at a screw dislocation, provided that the imaging conditions are the same for both. This result is shown in Fig. 1.a. Step 1 ends at a screw dislocation; therefore, step 2, which is lighter, must be one atom high.
A Fourier-transform spectrometer for infra-red cathodoluminescence in TEM
Authors: Spence J.C.H. , Isenman J. 
Published: June 2020

The study of the electronic structure of deep states associated with isolated, well characterised extended defects in semiconductors requires the use of a cathodoluminescence apparatus for TEM in the wavelength range 1-50 microns (1.2 - 0.02 eV). This would also allow the study of the III-V alloys and their defects used for I.R. emitters and lasers. Preliminary results using a grating spectrometer have been obtained by Petroff, however experience from Astronomy indicates that the Fellgett + Jacquinot advantage obtainable using Fourier Transform Infrared Spectroscopy (F.T.I.R.S.) is important for weak sources and noisy detectors. (See Davidson who has compared both techniques in SEM).The crucial design problem in the 1-10 micron range is the mirror movement in the Michelson Interferometer, which must be reproduceably positioned with submicron accuracy over a one centimeter range.
Arsenic segregation in polysilicon
Authors: Batson P.E. , Grovenor C.R.M. , Smith D.A. , Wong C. 
Published: June 2020

In this work As doped polysilicon was deposited onto (100) silicon wafers by APCVD at 660°C from a silane-arsine mixture, followed by a ten minute anneal at 1000°C, and in one case a further ten minute anneal at 700°C. Specimens for TEM and STEM analysis were prepared by chemical polishing. The microstructure, which is unchanged by the final 700°C anneal,is shown in Figure 1. It consists of numerous randomly oriented grains many of which contain twins.X-ray analysis was carried out in a VG HB5 STEM. As K α x-ray counts were collected from STEM scans across grain and twin boundaries, Figures 2-4. The incident beam size was about 1.5nm in diameter, and each of the 20 channels in the plots was sampled from a 1.6nm length of the approximately 30nm line scan across the boundary. The bright field image profile along the scanned line was monitored during the analysis to allow correlation between the image and the x-ray signal.
Memory disc defect characterization using SEM and energy-dispersive x-ray analysis
Authors: Bass R. A. , Brar A. S. 
Published: June 2020

In this era of computers, users of storage devices are requesting increased quantities of storage while maintaining or reducing the size of the package. This has meant a reduction in the size of a data bit and increased the susceptability of the media to microscopic defects, which occur in many shapes and sizes and at all stages of media processing. These processes are the machining of the raw substrates, coating the substrates, polishing the media and assembling the media in modules.In the past many of these defects could be overlooked since they didn't introduce missing bits in the read write process. The reason for this was the fact that the recording did not require a high track per inch or bit per inch packing density. Since all media specifications include requirements dealing with the quantity of missing bits or extra bit errors and their sizes; a study of media defects was implemented and the results are presented in this paper.