bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localization of the cystic fibrosis gene product in a transfected Sf9 insect cell line
Authors: Ackerley C.A. , Kartner N. , Riordan J.R. , Phillips M.J. 
Published: June 2020

The cystic fibrosis gene product (CFTR) is thought to be either directly or indirectly involved with Cl- conductance in epithelial cells in which it is produced. Utilizing the Baculovirus expression vector system, CFTR has been expressed in Sf9 insect cells which in turn display a regulated Cl- conductance employing the same techniques as those used to demonstrate Cl- conductance in epithelial cells. This was not observed in mock-infected Bgalactosidase producing or non-infected Sf9 cells.Two cell lines, one infected with CFTR expressing recombinant baculovirus and the other infected with B-galactosidase expressing recombinant baculovirus were fixed in 2% paraformaldehyde and 0.001% glutaraldehyde in 0.1 M HEPES buffer, PH7.2 for 2 hours. They were then rinsed several times with buffer, infiltrated with 2% agarose and infused with 2.3 M sucrose for at least 24 hours. The samples were then frozen by rapid immersion in liquid nitrogen cooled FREON 22 and ultrathin cryosections cut with a cryoultramicrotome and immunogold labelled with purified monclonal antibodies against CFTR (1) using the method described by Griffiths.
Elemental identification by x-ray images of pathologic tissue
Authors: Mumaw Virgil R. 
Published: June 2020

Elemental localization in biological specimens, using x-ray microanalysis, can best be demonstrated with x-ray images. X-ray images provide useful detail about elemental localization as well as relative quantitative information. The comparison of different elements using color overlay images graphically demonstrates interrelationships in ultrathin sections. Pathology specimens with unknown crystal formations were studied using x-ray imaging.Formalin fixed tissue from autopsy and surgical pathology were examined. For this study lung, lymph nodes and skin were used. Some specimens were removed from paraffin blocks and deparaffinized prior to processing for electron microscopy. Tissues were dehydrated and embedded in PolyBed epoxy resin (Polysciences, Warrington, PA). No osmium postfixation was used. Thin unstained sections were coated with carbon using a vacuum evaporator. The sections were examined and analyzed using a Philips EM 400 TEM/STEM microscope equipped with an EDAX PV9900 microanalyzer with the EDAX imaging package. X-ray images were collected using dwell times varying from 10 msec to 1 sec. Longer dwell times resulted in collection times as long as 14 hrs.
Antigen presentation between cultured cerebral smooth muscle and endothelial cells: Confocal laser scanning microscopy study
Authors: Ghoneim Shams , Fabry Zsuzsa , Keiner Judy , Hart Michael 
Published: June 2020

We have previously demonstrated with transmission and scanning electron microscopy that cultured endothelia and smooth muscle cells derived from cerebral microvessels can maintain their in vivo close relationship. This close association of the two cell population has functional implications which could explain humoral transmission of substances, the exchange of metabolites or play a significant role in autoimmune responses.It is generally accepted that the expression of antigen on the surface of a given cell is necessary for antigen presentation by that cell type. The role of antigen presentation and expression on brain cells could be significant in diseases such as multiple sclerosis (MS) and experimental allergic encephalitis (EAE).
IVEM and SEM images of whole cells cultured on EHS matrix (Matrigel)
Authors: Smith Nancy R. , Benson Stephen , Larabell Carolyn 
Published: June 2020

To investigate the interactions of cells with the extracellular matrix (ECM), rat lung fibroblasts (RLF) were cultured on an ECM extracted from EHS sarcoma to serve as an in vitro morphogenic model system. Surface features of RLF/EHS matrix interactions were viewed using the scanning electron microscope (SEM) and the intermediate voltage electron microscope (IVEM).For SEM, RLF were plated on EHS coated 13 mm glass coverslips at a density of 1 X 104/cm2. Coverslips were coated by spreading 25 μl of chilled EHS matrix (15 mg/ml) on the coverslip and incubating at 37° for 60 min. For IVEM, formvar coated gold grids were submerged in EHS matrix prior to polymerization. Controls consisted of cells grown on glass or gold grids minus ECM.
Ultrastructure of Plasmopara halstedii containing virus-like particles
Authors: Freeman Thomas , Gulya Thomas 
Published: June 2020

Mycoviruses have been found in more than 100 species of fungi and it is estimated that they may occur in as many as 500 species (Buck, 1986; Hollings, 1978; and Lemke, 1981). Mycoviruses range in size from small, isometric particles (25 nm in diameter) to long, flexuous rods exceeding 2000 nm in length, with the majority being isometric particles ranging in size from 25-50 nm (Buck, 1986). Mycoviruses hae been reported in all groups of fungi, but have been least frequently observed in the Oomycetes.Sunflower (Helianthus annuus) seedlings were inoculated with a North Dakota isolate of race 2 Plasmopara halstedii, the causal agent of sunflower downy mildew. Systemic disease symptoms developed within 14 days and samples were prepared for transmission electron microscopy using standard techniques.
An ultrastructural study of the epicuticle of Ascaris suum
Authors: Ramnani D. M. , Cain G. D. 
Published: June 2020

Ascaris suum, an intestinal parasite of swine, has a complex body wall, consisting of nine distinct layers when observed by transmission electron microscopy. The outermost layer of the cortex is a trilaminar region, the epicuticle, that is similar in appearance to plasma membrane. Parasitic nematodes interact with their hosts through this layer. The structure of the epicuticle is being studied with transmission and scanning electron microscopes.Parasites were obtained from an abattoir at Waterloo, Iowa, and maintained in Harpur's saline medium for up to two days. Cuticles were separated by microdissection and washed in 0.1M phosphate buffer, pH 7.2. Trump's universal fixative (4% Formaldehyde: 1% Glutaraldehyde in phosphate buffer, pH 7.2 ) was used for 1 h at room temperature for primary fixation. Surface charge of epicuticle was studied by incubating cuticle with cationized ferritin (Polysciences) at a concentration of lmg/ml in 0.1M phosphate buffer, pH 7.2, for 30 minutes at room temperature.
X-ray microanalysis and microbial colonization of leaves in Lake Wallenpaupack in eastern Pennsylvania
Authors: Majumdar S.K. , Daehler C.C. , Baker M.A. 
Published: June 2020

The microbial decomposition of leaf litter provides a major source of organic carbon and other nutrients and is important in ensuring the stability of lake ecosystems. Lake leaf litter can also act as a sink for immobilization of nutrients and elements. This investigation utilizes the scanning electron microscope and the energy-dispersive x-ray microanalysis technique to study the effects of agricultural or septic tank leakage pollutants on microbial colonization and elemental accumulation in leaves submerged in a lake in eastern Pennsylvania.White oak and red maple leaves were placed in mesh bags in the littoral zone of three cove sites at lake Wallenpaupack, a 13 mile-long, 5,700 acre lake located in the Pocono Mountains in eastern Pennsylvania. Cove 1 was surrounded by a wooded area and received water input from a wetland preserve. Cove 2 was suspected of contamination by septic tank leakage. Cove 3 received water input from a tributary passing through a heavily farmed drainage basin.
A comparison of CeB6 and LaB6 thermionic cathodes
Authors: Christman L. A. , Schwind G. A. , Swanson L. W. 
Published: June 2020

In recent years lanthanum hexaboride (LaB6) has proven to be an excellent thermionic cathode material, and has become the standard for most electron beam applications. The reasons that LaB6 is superior to tungsten as a material for thermionic cathodes are that it has a low work function and low volatility at high temperature. It is also relatively insensitive to most contaminants (or can at least be thermally cleaned of most contaminants).The most important consideration in cathode performance is its volatility at the operating temperature required for achieving the required current density. The work function for clean LaB6 is 2.6 eV compared with 4.5 eV for tungsten, thus it is possible to operate the former cathode at a considerably reduced temperature compared with tungsten. The volatility is greatly reduced, not only because of the lower operating temperature, but also because LaB6 has a relatively high heat of vaporization considering its low value of work function.
Chromosome structure and dynamics as revealed by 3-D and 4-D imaging
Authors: Swedlow Jason R. , Hiraoka Yasushi , Paddy Michael R. , Sedat John W. , Agard David A. 
Published: June 2020

Cellular DNA is packaged into chromosomes through complex processes whereby the DNA becomes compacted up to 10,000-fold by assembly into higher-order structures. In spite of many decades of intense study, the details of this process are not known. In addition, there is little information describing the dynamics of these higher-order structures during DNA replication, transcription, and mitosis. The goal of our laboratory is to use state-of-the-art 3-D imaging methods to understand how DNA is arranged into chromosomes and how chromosomes are spatially and temporally organized in the nucleus.Towards this end, we have developed a fluorescence microscope workstation optimized for collecting three-dimensional multi-wavelength data from fixed and living specimens. The multiplewavelength capability of this system allows us to simultaneously examine the spatial relationships of different chromosomal components in 3-D. Fixed samples can be labelled with up to three different fluorophore-conjugated antibodies and a fluorescent DNA binding dye, DAPI. Three-dimensional multi-wavelength data collection proceeds by sequentially recording images of each color, changing the focus, and then repeating the process as many times as necessary.
Confocal light microscopy and electrophysiology of neurons in culture
Authors: Turner J. N. , Szarowski D. H. , Fejtl M. , Ayrapetyan S. N. , Carpenter D. O. 
Published: June 2020

Cell volume changes and regulation are thought to be important in the physiology and pathology of neurons. Osmotic challenges alter a number of physiologic parameters including electrical properties, chemosensitivity, and Na pump activity. Thus, a good method for correlating images of the living cell's surface with electrophysiologic measures is needed, and we are exploring the use of confocal light microscopy for imaging neurons in culture.Isolated neurons from ganglia of Aplvsia California were plated on polylysine coated coverslips in L15 media with 20% hemolymph at room temperature. Cells stained with “Dil” were imaged with a Bio—Rad MRC—600 and an Olympus BH—2. Images were displayed using Bio—Rad's maximum projection procedure, or Vital Images’ Voxel View software run on an IBM RISC 6000 Powerstation 320. Electrophysiologic properties were assessed after imaging.
Quantitative chemical mapping: Spatial resolution
Authors: Ourmazd A. , Baumann F.H. , Bode M. , Kim Y. 
Published: June 2020

Quantitative Chemical Mapping is an electron microscopic technique capable of revealing compositional variations in crystalline materials. It combines chemical lattice imaging which maps the sample composition, with vector pattern recognition, which quantifies the local information content of the image to measure the local sample composition. Here we briefly address the spatial resolution of this technique, assuming complete familiarity with its theoretical underpinnings.In chemical imaging, we are concerned with the way that a compositional inhomogeneity is imaged under conditions appropriate for chemical sensitivity, and how the pattern recognition algorithm extracts information from a chemical lattice image. The problem can be formulated as follows. Given a “chemical impulse” of a specific shape, such as a column of Al atoms imbedded in GaAs (approximating a δ-function), an abrupt interface (a θ-function), or a diffuse interface (e.g., with an error function profile), what is the shape of the impulse on the analyzed chemical image? Or, alternatively, what region of the sample contributes to the information content of an image unit cell? By reciprocity, these two formulations are equivalent.
Computer recognition of symmetry in sad diffraction patterns
Authors: Jackson A. G. , Park J. , LeClair S. 
Published: June 2020

Applications of artificial intelligence to transmission electron microscopy are being studied in the context of a system that can learn to recognize images generated in transmission electron microscopy (TEM), provide interpretation of the imaging conditions, and provide assistance to the user in reaching conclusions about the experiment. Several computing programs exist which allow the TEM analyst to generate diffraction patterns, stereograms, lattices and structures for any inorganic crystal structure. These programs, however, do not act on their own. They require a knowledgeable user to strongly interact with them in order to generate the needed information.The first step beyond such a computation program is an expert system that has in it the collected observations and methodologies of an expert TEM analyst. The user must still interact strongly with the system via questions presented to the user or presented by the user. If a question is asked that is beyond the stored knowledge in the system, no action occurs. Although such a system would be of value to any TEM user, many experiments are conducted on materials that are new or for which information is not available.
A new Electron Microscopy tomography: Least squares pseudoimage reconstruction technique
Authors: Zhang Nengyu 
Published: June 2020

The least square pseudoimage (LSP) Reconstruction technique is based on matrix inversion. Due to the absence of information in electron microscopy, usually in an angle range from 60° to 90°, the matrix is degraded. The degraded matrix is used to compute two-dimensional (2D) projections of the three-dimensional (3D) object along the Z-axis (direction of the electron beam) and tilted around the Y-axis (tilt axis). Applying the pseudoinverse of the degraded matrix to electron micrographs, which are 2D projections of the 3D object, gives the pseudoimage.Since all of the slices which are perpendicular to the Y axis are related to the same degraded matrix, the 3D reconstruction problem can be simplified as series 2D reconstruction problems. All of the 2D pseudoimages are formed by the same pseudoinverse of a degraded matrix. In this case, however, the degraded matrix projects a 2D object onto an ID projection along the Z axis. Each slice is computed from a single line in all of the electron micrographs.
Calculated image contrast of vacancies in silicon crystal and representation of their contrast anomalies
Authors: Awaji M. , Hashimoto H. , Kinoshita T. 
Published: June 2020

Images of small lattice defects have been observed as a contrast anomaly recently by HREM. However, the observed images are generally mixed with the contrast anomalies which come from the quantum noise, contamination etc. Therefore, it seems to be useful to know the calculated image and to compare with the observed ones. In this paper, calculated image contrast of Si containing vacancies is studied.The stress field due to a stacking fault tetrahedron (SFT) proposed by Yoffe has been extrapolated to that of a vacancy. Since the atomic structure around the vacancies is not yet clearly known, it is assumed that a pair of vacancies in Si behaves like single vacancy in f.c.c. crystals. Figure 1 shows a pair of vacancies position (®-®) in a large unit cell with 0.38nm thickness of Si crystal projected to [110]. It is necessary for this calculation to have the large unit cell because the stress field effects on the atom positions at an infinite distance.
High-angle annular dark-field STEM imaging of doped semiconductor layers
Authors: Perovic D.D. , Paterson J.H. 
Published: June 2020

With the development of crystal growth techniques such as molecular beam epitaxy (MBE), it is now possible to fabricate modulation-doped superlattices consisting of alternating ultrathin layers of n-and/or p-type material abruptly separated by undoped material. At sufficiently high dopant concentrations these abrupt layers may be imaged in cross section by electron microscopy. Pennycook et al. and Treacy et al. have used high angle annular dark-field (HAAD) imaging in the scanning transmission electron microscope (STEM) to image low levels of dopants (∼1 at. %) in semiconductors. This work is concerned with imaging boron and arsenic doped layers in silicon at levels « 1 at.%.Fig. 1 shows a HAAD image of a B-Si superlattice at the <110> zone-axis orientation taken at 100 kV using a VG HB501UX STEM. The bright vertical layers are the B-doped regions, containing ∼4 x 1020 B/cm3. The horizontal lines are due to beam instability while the image was recorded. Fig.2 shows a line scan across the same superlattice, recorded by scanning the beam across the specimen in a direction perpendicular to the layers.
Silicon vibration amplitude determined by energy-filtered CBED
Authors: Xu Peirong , Loane Russell , Silcox John 
Published: June 2020

The frozen phonon method was recently developed to include the effects of thermal vibrations in the multislice calculation. In this method, each atom in the simulated specimen is displaced by a random amount which follows a Gaussian distribution with a standard deviation equal to the atomic vibration amplitude. Convergent beam electron diffraction (CBED) patterns calculated by this technique contain Kikuchi bands and a thermal diffuse background which were matched quantitatively to experimental Si (100) CBED patterns for scattering angles up to the first order Laue Zone. In this paper, we report the measurement of the room temperature silicon vibration amplitude from comparison of energy filtered CBED with frozen phonon calculations.The energy filtered Si (100) patterns were obtained with a VG HB501A STEM in microdiffraction mode by fixing a convergent probe (7.5mrad half angle, probe size ≈ 40Å) on the specimen and scanning the post specimen electrons over a small axial collector aperture (1.6mrad).
TEM characterization of metallization systems in VLSI
Authors: Mitwalsky A. , Oppolzer H. 
Published: June 2020

Detailed knowledge of the properties of metallization systems used in silicon VLSI technolgy is essential to evaluate application and to achieve stable device operation. The progressively shrinking device dimensions require analytical techniques allowing to detect interfacial reactions or precipitation with nanometer resolution, particularly for the development of new processes. Transmission electron microscopy (TEM) of thin cross sections represents a powerful tool for obtaining such information directly. In addition to imaging analytical TEM allows phase and element identification with high spatial resolution.The interaction during processing between silicides of various metals (Ti, Co, Ta and W) and different dopants (B, As) in silicon was investigated since possible metal dopant reactions may lead to dopant depletion in the silicon. In the case of Ti and Ta silicide the formation of metal dopant compounds during heat treatment was indeed observed by scanning electron microscopy and TEM.
Characterization of homoepitaxial diamond films by Electron microscopy
Authors: Malta D.P. , Willard S.A. , Rudder R.A. , Hudson G.C. , Posthill J.B. , Thomas R.E. , Markunas R.J. 
Published: June 2020

Semiconducting diamond films have the potential for use as a material in which to build active electronic devices capable of operating at high temperatures or in high radiation environments. A major goal of current device-related diamond research is to achieve a high quality epitaxial film on an inexpensive, readily available, non-native substrate. One step in the process of achieving this goal is understanding the nucleation and growth processes of diamond films on diamond substrates. Electron microscopy has already proven invaluable for assessing polycrystalline diamond films grown on nonnative surfaces.The quality of the grown diamond film depends on several factors, one of which is the quality of the diamond substrate. Substrates commercially available today have often been found to have scratched surfaces resulting from the polishing process (Fig. 1a). Electron beam-induced current (EBIC) imaging shows that electrically active sub-surface defects can be present to a large degree (Fig. 1c). Growth of homoepitaxial diamond films by rf plasma-enhanced chemical vapor deposition (PECVD) has been found to planarize the scratched substrate surface (Fig. 1b).
Fresnel fringe contrast in the TEM: Application to study the microstructure of amorphous silicon
Authors: Kannan V. C. 
Published: June 2020

Amorphous silicon-hydrogen (α - Si:H) alloy films deposited by plasma enhanced chemical vapor deposition (PECVD) of silane exhibit a remarkable property; namely, the films are practically insulators in the as deposited state. When sandwiched between two metals or highly conductive refractory metal silicides, the films can be converted to near conductivity state by “programming” the sandwich structure to complete dielectric breakdown of the insulator. Such α - Si:H films are used in permanently programmable integrated circuits such as PGA (Programmable Gate Arrays) as “antifuse” materials.TEM technique has, usually, limited application to study the microstructure of amorphous materials since they do not exhibit the well understood diffraction contrast as seen in crystalline materials. However, Fresnel fringe contrast due to electron interference effects at either sides of interfaces or at the edges can be used to provide the sort of information needed to characterize amorphous films. The profiles of Fresnel fringes are often complex for interface thickness of <100 A and their shape and contrast are very sensitive to compositional changes on either sides of the interfaces.
HREM and EDX studies of layered bimetallic colloids
Authors: Bovin Jan-Olov , Malm Jan-Olle 
Published: June 2020

Bimetallic clusters and colloids are interesting for several reasons. They may serve as objects for studies of the formation of different alloys, furthermore novel catalytic activities are to be expected. It is also possible to save precious metal, like Pt, by optimizing the synthetical conditions so that only very thin surface layers occur. This paper describes the identification of the shell structure of such particles by high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray (EDX) microanalysis.Gold colloids with a diameter of 18 nm can be covered with platinum or palladium shells, in aqueous solution. The new layered colloid shows a metallic luster. The HRTEM studies were performed in a JEM-4000EX with a structural resolution of 0.16 nm and the EDX analysis was done in a JEM-2000FX equipped with a LINK 10000 system.