bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructural Studies on L1210 Cells Sensitive or Resistant to Actinomycin-D.
Authors: Calvelli T. A. 
Published: June 2020

The L1210(V)gln-cell line, which requires glutamine for growth, was established as a suspension culture by Hutchison et al. (1) from an ascites tumor maintained in BD2F1mice (C57BL X DBA/2). A variety of particles having the morphology of intracytoplasmic-A, type-B and type-C oncornaviruses have been observed in the solid, ascitic (2;3) and tissue culture forms(4;5;6) of the L1210 cells. A subline of the L1210(V)gln-line, 2000-fold resistant to actinomycin-D exhibits low tumorigenicity and is immunogenic inBD2F1mice.Cells of the parent, drug-sensitive line are primarily of lymphoid morphology, i.e. spherical with a large central nucleus. Occasionally they have lobulated or multiple nuclei, marginated heterochromatin, and a single prominent nucleolus. Although some rough endoplasmic reticulum is visible in sensitive cells, the majority of polysomes are found free in the cytoplasm.
Living Plants Continue to Grow After Examination by Scanning Electron Microscopy
Authors: Sowers Arthur E. 
Published: June 2020

It has been found that, within the constraints and limitations described below, the same individual living plant, Urtica pilulifera (common name - Stinging Nettle), continues to grow after repeated brief (6 minute) examination by conventional scanning electron microscopy. Fig. 1-3 show the simultaneous initiation and synchronous elongation of many epidermal hairs in the same area on the first internode of the same plant. The time interval between examinations was 24 hours.Seeds of Urtica pilulifera were germinated in vermiculite, the above ground part separated from the roots by a perpendicular cut with a razor and transferred to an hydroponic solution. Germination and transfer of the above ground parts were timed such that the plants were at a stage of morphogenesis shown in Fig. 4 at the start of the daily SEM examinations.
Electron Microscopy of Silicon Deposits in Foliar Idioblasts of Magnolia Grandiflora
Authors: Postek Michael T. 
Published: June 2020

Silicon occurs naturally in plants in the form of its hydrated oxide (SiO2.nH2O) commonly called silica. Silica has been shown to be a necessary element in the normal development of many plants, playing an array of roles including strengthening, protection, and reduction of water loss. Deposition of silica in various portions of the plant body, especially the leaves, may also be viewed as a way for the plant to dispose of any excess silica taken up beyond that necessary for normal metabolism.Studies of this “opaline” silica have thus far been limited to species of the Cyperaceae and Gramineae known to possess significant quantities of silica. Within the Magnoliaceae, certain “glistening” idioblast cells at the foliar veinlet termini and vein sheaths of Magnolia grandiflora (1) have been suspected to be siliceous in nature.
Electronmicroscopic Mass Determination Without A Densitometer: Quantitative Electron Microscopy Using Photographic Methods
Authors: Lamvik M. K. 
Published: June 2020

Zeitler and Bahr showed that the mass of a microscopic object could be determined in the electron microscope, since there is a straightforward relationship between the mass thickness of a point on an object and the transmission of a corresponding point on the electron micrographs. Analysis of such micrographs usually requires specialized equipment for densitometry, but here a simple photographic method will be applied to the determination of mass thickness from electron micrographs.Polystyrene spheres are convenient objects for mass calibration due to their spherical shape. For a sphere of radius r, the thickness 2z of any point a distance x away from the center of the sphere is given bythus, the sphere is a continuous calibration standard for thicknesses from 0 to 2r. As a convenient substitute for a densitometer, a high contrast film can be used to copy an original.
Scanning Electron Diffraction: Principles and Techniques
Authors: Maher Dennis M. 
Published: June 2020

In this summary the principles and techniques of scanning electron diffraction (SED) in a conventional transmission electron microscope (CTEM) equipped with a scanning attachment will be outlined. For a comprehensive review on this subject see Ref. [l].Let us assume that this CTEM has been modified so that scanning above and below the specimen are possible. Figure 1 shows a cross-section of such an optical system where scan coils 1 and 2 are used to deflect the incident electron beam and scan coil 3 to deflect the transmitted electrons. For discussion purposes the modes of operation will be subdivided into two classifications, namely undeflected and deflected illumination. For undeflected illumination (i.e. transmission scanning electron diffraction, TSED) the transmitted, scattered-electron distribution is time independent in the sense that all object points are irradiated simultaneously and the illuminating angle is constant.
Quantitative Elemental Analysis of “Transparent” Particles in the Tem
Authors: Sprys J. W. , Short M. A. 
Published: June 2020

The quantitative elemental analysis of small particles can be performed in the transmission electron microscope by use of an energy dispersive X-ray detector and multichannel analyzer. As recently suggested by Cliff and Lorimer (1), Equation 1is used to determine a calibration curve of X-ray intensities relative to silicon for the accurate chemical analysis of thin particles. In this equation, I1 and I2 are the measured characteristic X-ray intensities of the two elements in question, C1 and C2 are the weight fractions and k is a proportionality constant. Absorption, atomic number and fluorescence corrections in transparent particles are assumed to be negligible at an electron accelerating voltage of 100 keV.
In Situ Experiments in the High Voltage Electron Microscope
Authors: Butler E. Paul 
Published: June 2020

Cellular decomposition in Ni-60wt%AuBoth cellular and spinodal decomposition into Au-rich and Ni-rich phases occur when this alloy is aged. In situobservations allowed single cell colonies to be studied as they grew through and consumed the spinodally decomposed matrix, and also provided values for the interlamellar spacing S, and growth rate G, at different temperatures. At 415°C cellular growth proceeded at an average rate of 57Å/s (Fig. 1) with S = 855Å and a compositional ratio K of 0.7. Substituting these values in the modified equation for cellular growth as if controlled by cell boundary diffusion, G = KDbδ/S2 with published values of Db and δ=5Å, gave G = 48Å/S, in good agreement with the experimentally observed growth rate.
Rapid Sem-Microprobe Identification of Mineral Inclusions in Drilled Cores
Authors: Feuerbacher D.G. , Cordova M.H. 
Published: June 2020

Analysis of micro-inclusions and particulates in core samples is quite important in the geological classification of sedimentary formations as well as in choosing proper drilling fluids, completion systems, and in other oil-field operations. SEM-x-ray microprobe techniques, using energy dispersive detectors, are widely used in mineral analysis, but quantitative analysis is often difficult or time-consuming because of 2 the need for a multi-element standard and sophisticated computer software.A rapid method of SEM-x-ray micro-analysis of mineral inclusions was investigated. Using freshly-cleaved carbon coated crystals of selected minerals, x-ray spectra were first made of a planar area of each crystal, using the same conditions (see Table 1) each time. The spectra thus obtained were stored on the IBM-type floppy disk by a special MCA datatransfer function (developed by Ortec, Inc.).
Third-Order Aberration Correction in the Sem and Stem
Authors: Parker N. W. , Golladay S. D. , Crewe A. V. 
Published: June 2020

The resolution and field of view attainable in electron microscopes is limited by third-order aberrations of the optical system. While considerable effort has been made to determine the effects of these aberrations on the CTEM, little work has been done for the case of the STEM, We have found that one of the advantages of the scanning microscope (both STEM and SEM) is that all third-order aberrations can be eliminated, which is not possible in the CTEM.Spherical aberration may be cancelled using a non-cylindrically symmetric system of lenses as first suggested by Scherzer. An example of such a system would be the quadrupole-octupole corrector first constructed by Deltrap and currently being applied to a 100 kV STEM by Beck and Crewe. If one wishes to increase the field of view attainable, the remaining seven geometrical aberrations become the limiting factors. These aberrations, in roughly decreasing order of importance, are isotropic and anisotropic coma (S6and S7coefficients), isotropic and anisotropic astigmatism (S4and S5), curvature of field (S3) and isotropic and anisotropic distortion (S1and S2).
Quantitative microanalysis by electron energy-loss spectrometry
Authors: Egerton R.P. , Rossouw C.J. , Whelan M.J. 
Published: June 2020

For elements in the first and second rows of the periodic table, microanalysis based on K-shell energy-loss spectra has two major advantages over x-ray emission methods: (1) The K-loss signal remains high, whereas the x-ray production efficiency is less than 10%. (2) The collection efficiency can be better than 30%,since most of the inelastically scattered electrons lie within 5° of the forward direction.The practical problems are concerned not so much with the relatively low intensity of K-shell losses as with the background contribution to the spectrum due to valence-electron excitation. The latter can be corrected for by extrapolation of the spectrum preceding the K-edge but this procedure becomes inaccurate in the case of a low signal-to-noise ratio or a large range of extrapolation. Therefore it is desirable to measure the loss electrons over as small an energy window as possible, consistent with an adequate K-loss signal/noise ratio.
Use of LaB6for a High Quality, Small Energy Spread Beam in an Electron Velocity Spectrometer
Authors: Batson P. E. , Chen C. H. , Silcox J. 
Published: June 2020

Electron energy loss experiments combined with microscopy have proven to be a valuable tool for the exploration of the structure of electronic excitations in materials. These types of excitations, however, are difficult to measure because of their small intensity. In a usual situation, the filament of the microscope is run at a very high temperature in order to present as much intensity as possible at the specimen. This results in a degradation of the ultimate energy resolution of the instrument due to thermal broadening of the electron beam.We report here observations and measurements on a new LaB filament in a microscope-velocity spectrometer system. We have found that, in general, we may retain a good energy resolution with intensities comparable to or greater than those available with the very high temperature tungsten filament. We have also explored the energy distribution of this filament.
The use of Direct Phasing Methods for Single Crystal Electron Diffraction Data. I. Methylene Subcells
Authors: Dorset D. L. , Hauptman H. A. 
Published: June 2020

The significant impediment to the use of electron diffraction data for crystal structure analysis is, of course, the perturbation of n-beam dynamical effects. In more severe cases this dynamical perturbation gives an intensity distribution in the diffraction pattern which is not directly related to the underlying crystal structure, thus making the determination of complex structures nearly impossible by this technique.However, as was experimentally established in Vainshtein's laboratory and is theoretically predicted, the diffraction of electrons from thin mosaic crystals composed of light atoms is in accord with kinematical theory to a good first approximation and, furthermore, ab initiocrystal structure analyses are tractable viastandard crystallographic phase determination. To date the few electronographic determinations of unknown organic structures have used either trial and error or Patterson techniques.
An Image Intensifier and Polaroid Camera for the Tem
Authors: Turnbull T. P. , Fullam Ernest F. , Shaffer Charles 
Published: June 2020

Ever since the transmission electron microscope was invented and introduced into the scientific laboratory as a working tool, there have been two features desired by most microscopists which have never been completely fulfilled by the manufacturers of the instrument at reasonable cost. The first, adequate intensity at all magnifications and sufficient illumination of the screen when viewing heat-sensitive specimens. A second most desired feature is instant photography of what is being observed on the fluorescent screen. These two desired features are now available by adapting on the shelf devices to the TEM.The first device is for intensifying the image normally viewed on the fluorescent screen for critical focusing, contrast enhancement for specimen scanning without burning up the sample by excessive electron bombardment or by increasing specimen contamination. A second device is a method of simple outside the column photography without image grain or distortion and without alteration to the normal operation of the electron microscope.
Electron Beam Damage at Low Temperatures
Authors: Ramamurti K. , Crewe A. V. , Isaacson M. S. 
Published: June 2020

While significant advances have been made recently in obtaining specimen detail at near atomic resolution, electron beam damage continues to be a limiting factor for biological specimens. The techniques developed to circumvent this limitation depend upon keeping the damage to a minimum. A complementary approach that reduces the damage itself would be of considerable advantage. We would like to discuss the implications of a cooled specimen in the light of low temperature measurements reported so far.The specimen in the microscope can be characterized by its physical and chemical states, and any changes due to electron beam damage can be monitored by changes in mass, electron diffraction pattern and energy-loss spectrum. Most of the low temperature measurements reported so far (see Ref.
Tem and Stem Microanalysis
Authors: Russ J. C. 
Published: June 2020

The technique widely know as “Analytical Electron Microscopy” is now being applied in a great variety of scientific and technical fields. It combines the examination of specimen morphology and structure with elemental analysis.The characteristic X-rays generated in the sample can be used to obtain elemental analysis of the region of the sample being hit by the electrons. The traditional electron probe microanalyzer used this method with wavelength-dispersive diffracting spectrometers . The advent of the SEM with its much lower electron beam currents (in order to achieve smaller beams for high resolution images) and rough samples (which do not lie on the focusing circle of a wavelength-dispersive spectrometer) nurtured the development of the energy-dispersive X-ray analyzer. The further use of this new method with the TEM and STEM has opened up entire new areas of application.As the name implies, the energy-dispersive spectrometer measures X-ray energy directly producing a spectrum of counts versus energy. The combination of higher geometrical and detector efficiency means that ED detectors can give count rates up to several hundred times greater than the WD spectrometer.
Progress in Aberration Correction in the Stem
Authors: Beck V. , Crewe A. V. 
Published: June 2020

A STEM which includes a corrector for primary spherical aberration has been built and is being put into1operation. The microscope is expected to achieve a resolution of 1 Å at 50 keV. This high resolution is possible because of the correction of spherical aberration.The corrector and its operation have been described in detail elsewhere. Briefly, the corrector consists of non-cylindrically symmetric elements, four quadrupoles and three octupoles, which produce a negative primary spherical aberration. This cancels the positive spherical aberration which arises from the cylindrically symmetric objective lens as a result of Scherzer's theorem.The corrector and objective are physically separated by 23 cm. This separation causes secondary spherical aberration (C5= 18 cm) and it is this aberration which limits the microscope's resolution.
Scanning Electron Microscope Study of the Effect of Structure on the Liquefaction of New Mexico Coals
Authors: Murr L.E. , Wongwiwat K. 
Published: June 2020

While it is well known that certain pulverized coals can be liquified above ground in controlled conditions of solvent, pressure, and temperature; liquefaction of other coals is difficult to achieve. In the face of an increased demand for energy, and on considering the abundant supply of coal in parts of the United States, innovative research has been initiated to attempt to liquify coal in-situ using well-bore techniques which are essentially the same as those employed for petroleum production. In attempting in-situ liquefaction, the coal reaction face is essentially unpulverized, and liquefaction generally requires high temperatures (>400°C) and pressures (>2000 psi).The liquefaction processes involved in the hydrogenation or solution mining of coal are dependent upon both physical and chemical properties involving the structure and composition (including mineral impurities and trace elements) of the coal, the solvent, the surface area exposed - including particle size, homogeneity, cracks, pores, etc. - pressure, temperature, and catalyst. All of these properties in a consonant manner will control the rate and extent of liquefaction.
Antiphase Boundaries in Low Temperature Phases of Gd2 (M0O4)3, LaAlO3 & SrTiO3
Authors: Yagi K. , Yamamoto N. , Honjo G. 
Published: June 2020

From space group relationships of structures of high and low temperatures phases of Gd2(Mo0i,)3 (1), LaA1O3 and SrTiO3, antiphase boundaries (APBs) are expected to exist in the low temperature phases of these substances in addition to domain boundaries due to slight distortions of the lattices. The APBs may be considered to be formed due to the difference in phases of condensing soft modes from place to place.1. Gd2(MoO4)3. In addition to antiparallel ferroelectric domain boundaries which show so called 6-type asymmetric fringes, a-type symmetric fringes due to APBs were observed below the transition point 160°C (Fig. 1) (2). Since the unit cell of the low temperature phase is two times as large as that of the high temperature phase APB should not have been seen under excitations of fundamental reflections such as (2h O O) and (O 2k O), if the displacement vector at the APB were R茸 = (a+b). The fact that it is seen in Fig. 1 means that there is an additional displacement AR due to lattice relaxation at the boundary.
Interactions Between Al and Cr Thin Films
Authors: Anderson R. M. , Reith T. M. , Sullivan M. J. , Brandis E. K. 
Published: June 2020

Thin films of aluminum or aluminum-silicon can be used in conjunction with thin films of chromium in integrated electronic circuits. For some applications, these films exhibit undesirable reactions; in particular, intermetallic formation below 500 C must be inhibited or prevented. The Al films, being the principal current carriers in interconnective metal applications, are usually much thicker than the Cr; so one might expect Al-rich intermetallics to form when the processing temperature goes out of control. Unfortunately, the JCPDS and the literature do not contain enough data on the Al-rich phases CrAl7 and Cr2Al11, and the determination of these data was a secondary aim of this work.To define a matrix of Cr-Al diffusion couples, Cr-Al films were deposited with two sets of variables: Al or Al-Si, and broken vacuum or single pumpdown. All films were deposited on 2-1/4-inch thermally oxidized Si substrates. A 500-Å layer of Cr was deposited at 120 Å/min on substrates at room temperature, in a vacuum system that had been pumped to 2 x 10-6 Torr. Then, with or without vacuum break, a 1000-Å layer of Al or Al-Si was deposited at 35 Å/s, with the substrates still at room temperature.
Observation of Gas Bubbles in Vapor-Deposited Gold Films
Authors: Lloyd J. R. , Nakahara S. 
Published: June 2020

Voids or gas hubbies have been observed in sputtered and evaporated gold films, following post deposition annealing. Small voids have also been observed in gold films after electromigration (EM). AS few voids are visible before annealing or prior to EM, it was concluded that these processes are responsible for the principal mechanism for void formation. We have made a further study on the formation of voids or gas bubbles in as-deposited as well as annealed gold films which are prepared by vapor deposition. It is demonstrated that a large number of voids (< 50 Å) are, in fact, present in gold films prior to annealing or EM.Single-crystal gold films were grown epitaxially by vapor deposition onto KC1 substrates held at 250°C in an ion-pump vacuum of 1 x 10-5 Torr. In order to obtain a variation in deposition rate within a single sample, deposits were made through a mask separated from the substrate, resulting in significant shadowing.
The Structure of Ion-Deposited Crystalline Carbon Films
Authors: Joy D. C. , Spencer E. G. , Schmidt P. H. , Sansalone F. J. 
Published: June 2020

Polycrystalline carbon films deposited by an ion source were first studied by Aisenberg and Chabot. Because of the problems they encountered in characterizing these films we have examined similar films made in an apparatus of the type shown in Fig. 1. Samples were deposited on to substrates of NaCl, KC1 or silicon in thicknesses up to 2 μm. Prior to examination in the TEM, the films were dissolved from their substrate material and mounted on grids. The films were highly insulating (∼lO12 ohm cm), optically clear and totally resistant to attack by all common solvents. From ellipsometric measurements the index of refraction was found to be ∼2. Ion backscattering and Auger studies showed the samples to be pure carbon except for the presence of a few percent of the carrier gas (argon, krypton, etc.).Figure 2 shows a micrograph typical of such a film. Crystallites varying in size up to a maximum of a few microns are found randomly distributed over the sample. In general the morphology of the crystals is typical of a cubic symmetry, with a predominance of 90° edges. As the film thickness increases there is a tendency for existing crystals to act as substrates for new crystals.
Direct Observation of the Growth of Sputtered Gold Films on (111) Silicon Substrates
Authors: Lee J. I. , Maa J. S. , Hutchinson Thomas E. 
Published: June 2020

The study of in situ Ion beam sputtering of gold on substrates of single crystal silicon using well controlled ultrahigh vacuum deposition system shows that substrate/overgrowth interactions involving alloying and interdiffusion greatly influence the growth and structure of sputtered thin gold films.Gold was sputter deposited on substrates of single crystal at temperatures ranging from 23°C to 500°C and a deposition rate of 15Å/min in vacuum of 2x10-8 torr. The growth and structure of the deposits shows large differences in two substrate temperature regions, the low temperature regions below 200°C and the high temperature regions above 200°C. At low substrate temperatures below 200°C, an amorphous film is first formed as shown in Figure la and followed by the growth of two dimensional polycrystalline gold islands on the newly formed amorphous layer as shown in Figure lb. At high substrate temperatures above 200°C, a liquid alloy of Au-Si and polycrystalline silicon rich regions are formed on the substrate as shown in Figure 2a. The liquid alloy of Au-Si and polycrystalline silicon rich regions are phase transformed to the polycrystalline gold and silicon rich regions during cooling to room temperature as shown in Figure 2b.