bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complex Vesicles, Microtubules, and Cytoplasmic Filaments in the Endothelial Cells of Normal Dog Aorta
Authors: Sun C. N. , Ghidoni J. J. 
Published: June 2020

Endothelial cells in longitudinal and cross sections of aortas from 3 randomly selected “normal” mongrel dogs were studied by electron microscopy. Segments of aorta were distended with cold cacodylate buffered 5% glutaraldehyde for 10 minutes prior to being cut into small, well oriented tissue blocks. After an additional 1-1/2 hour period in glutaraldehyde, the tissue blocks were well rinsed in buffer and post-fixed in OsO4. After dehydration they were embedded in a mixture of Maraglas, D.E.R. 732, and DDSA.Aldehyde fixation preserves the filamentous and tubular structures (300 Å and less) for adequate demonstration and study. The functional significance of filaments and microtubules has been recently discussed by Buckley and Porter; the precise roles of these cytoplasmic components remains problematic. Endothelial cells in canine aortas contained an abundance of both types of structures.
Record Wear Studies by Scanning Electron Microscopy
Authors: Coutts M.D. , Levin E.R. , Woodward J.G. 
Published: June 2020

While record grooves have been studied by transmission electron microscopy with replica techniques, and by optical microscopy, the former are cumbersome and restricted and the latter limited by lack of depth of focus and resolution at higher magnification. With its great depth of focus and ease in specimen manipulation, the scanning electron microscope is admirably suited for record wear studies.A special RCA sweep frequency test record was used with both lateral and vertical modulation bands. The signal is a repetitive, constant-velocity sweep from 2 to 20 kHz having a duration and repetitive rate of approximately 0.1 sec. and a peak velocity of 5.5 cm/s.A series of different pickups and numbers of plays were used on vinyl records. One centimeter discs were then cut out, mounted and coated with 200 Å of gold to prevent charging during examination. Wear studies were made by taking micrographs of record grooves having 1, 10 and 50 plays with each stylus and comparing with typical “no-play” grooves. Fig. 1 shows unplayed grooves in a vinyl pressing with sweep-frequency modulation in the lateral mode.
In Situ Electron Microscope Investigations of the Growth and Structure of Thin Films
Authors: Hutchinson Thos. E. 
Published: June 2020

Few areas of investigation have benefited more from the use of the electron microscope than thin films. This is most strikingly demonstrated by the state of knowledge of the structure and growth mechanisms prior to and subsequent to electron microscope investigations.The use of the electron microscope as an experimental chamber in which both growth and observation take place simultaneously, has been responsible primarily for the broad quasi-quantitative view of the process of formation of thin films we now hold. The great advantage of the in situ experimental arrangement lies in its ability to examine in detail the time sequence of events occuring during thin film nucleation and growth. Each stage in the process of formation of thin films has been examined, and although questions still remain as to the exact mechanisms involved, the general features are well characterized. These are nucleation of ad-atom clusters on the substrate, growth of the atom clusters both laterally and perpendicular to the substrate, coalescence of the nuclei into larger sub-units and finally, elimination of channels between the extended islands.
Application of Electron Diffraction to Problems in Biological Electron Microscopy
Authors: Glaeser R. M. , Thomas G. , Christensen R. , Brammer W. G. 
Published: June 2020

The role of elastic (Bragg) scattering in relation to contrast and advanced electron microscopy of biological materials has not been investigated in the detail that is now common with inorganic crystals. It is the object of this paper to demonstrate the application of selected area diffraction, dark field imaging and low angle Fourier contrast to biological materials. Essential differences between the mechanisms of diffraction image-contrast are due to the larger lattice spacings in biological structures, which invariably result in Fourier image contrast. Crystals with spacings greater than 10Å can be expected to show Fourier contrast under normal microscope operations.Samples of crystalline amino acids were grown by solvent evaporation on formvar coated specimen grids. Specimen grids were scanned and selected on the basis of appearance in a polarization-optical microscope (see Fig.1). All crystalline amino acids tested were extremely sensitive to damage in the electron beam.
Urinary stone analysis
Authors: Khan Saeed R. 
Published: June 2020

Since crystalline composition of a urinary stone is an expression of urinary chemical conditions prevalent at the time of crystal nucleation and growth, a careful analysis of the stone and identification of constituent crystals is necessary for an understanding of the disease and the initiation of a proper medical regimen for the prevention of stone recurrence. Of the number of methods available, analytical electron microscopic techniques including scanning (SEM) and transmission electron microscopy (TEM), x-ray microanalysis (XRMA), and electron diffraction (ED) are gaining in popularity.For SEM, the dried stone is fractured through the middle and small pieces representing different areas of the stone are mounted on a carbon planchet or an aluminum stub using a double sticky tape or graphite paint. The specimen is then sputter coated with silver, gold or gold/palladium; or coated with carbon. For morphological examination alone, the specimen can be coated with any of the available conducting substances, but for XRMA the specimen should either be examined uncoated or be coated with carbon, or with a substance whose peaks in the XRMA spectrum do not interfere with the peaks of the elements of interest.
Mass Accuracy in the STEM
Authors: Wall J. S. 
Published: June 2020

The scanning transmission electron microscope (STEM) has a number of features which make it ideal for quantitative studies: 1) large acceptance angle scintillator-photomultiplier detectors for low dose dark field imaging with linear electron detection, 2) simple contrast transfer function with no oscillations, 3) cold stage for zero contamination and reduced mass loss, 4) digital scanning for accurate magnification and positioning and 5) serial readout of several signals simultaneously for direct interfacing to a computer.For the past 10 years the Brookhaven STEM has been used for mass measurements on isolated individual molecules in freeze dried biological specimens. Interpretation of dark field STEM images is straightforward because of the clean background and linearity of the entire imaging process. Mass measurements provide a quantitative link to biochemical studies. Tobacco mosaic virus (TMV) usually is included along with the specimen of interest as a measure of the quality of the freeze drying and as a check on the microscope calibration, but is not necessary for absolute mass measurements.
Ultrastructure of Testicular Spermatozoon of the Fish Oreochromis Niloticus
Authors: Guha T. , Siddiqui A. Q. , Prentis P. F. 
Published: June 2020

Tilapia, Oreochromis niloticus, is an economically important fish in Saudi Arabia. Elucidation of reproductive biology of this species is necessary for successful breeding program. In this paper we describe fine structure of testicular sperm cells in O, niloticus.Testes from young adult fish were fixed in gluteraldehyde (2%) and osmium tetroxide (1%), both in cacodyl ate buffer. Specimens were processed in the conventional way for electron microscopy and thin sections of tissues (obtained by cutting the blocks with a diamond knife) were stained by ura- nyl acetate and lead citrate. These were examined in a Carl Zeiss electron microscope operated at 40 kV to 60 kV. Sperm cells were obtained from testes by squeezing them in cacodyl ate buffer. They were fixed in gluteraldehyde (2%) in the same buffer, air dried, gold coated and then examined in a Philips scanning electron microscope (SEM) operated at 25kV.The spermatozoon of O. niloticus is consisting of head, midpiece and tail (Fig. 1).
Chlorotrifluoroethylene (CTFE) Oligomer: Effect on Livers of Fischer-344 Rats
Authors: Mattie D.R. , Chase M.R. , Kinkead E.R. , Whitmire R.E. 
Published: June 2020

Chlorotrifluoroethylene (CTFE) oligomer is a nonflammable, saturated, hydrogen-free halocarbon oil with chain lengths of six to ten carbons. CTFE was seen to have a low degree of toxicity in acute toxicity tests. A subchronic study was conducted because CTFE is an excellent candidate hydraulic fluid. The objective of this electron microscopic investigation was to examine and compare the livers of male and female rats after inhalation exposure to CTFE for 90 days.Male and female Fischer-344 rats were exposed to 0.25, 0.5, or 1.0 mg/L CTFE aerosol for 90 days, 6 h/day, 5 days/week. An equal number of control rats were exposed to air only. Following the 90-day exposure period, 10 male and 10 female rats were sacrificed from each group. A 1mm slice of the left lobe of the liver of three rats of each sex and each group was collected for transmission electron microscopic examination.
Calcium/phosphorus ratios of femurs of male and female fischer-344 rats exposed to halocarbon 27-S
Authors: Mattie D.R. , Maslanka J.J. , Flemming C.D. 
Published: June 2020

Halocarbon 27-S (H 27-S) is a polymer of chlorotrifluoroethylene (CTFE). Since metabolism of CTFE yields inorganic fluoride, it was believed that H 27-S would also yield fluoride in the blood. Exposure to fluorine results in deposition in bone as calcium fluoride or fluorapatite. Deposition of fluoride in the bone matrix should result in an altered calcium phosphorus ratio (CaP). The objective of this study was to determine the CaP of femurs of male and female rats exposed subchronically to H 27-S using energy dispersive x-ray analysis techniques and to compare CaP from exposed rats with the CaP of control rats.Male and female rats were dosed daily with 2.5 g H 27-S/kg body weight by gavage for 7 or 21 days. Rats were sacrificed at 7, 21 and 35 days (14 days after the 21 day dosing). Femurs of three rats of each sex and each group were analyzed.
Determination of ionization cross section by electron spectroscopic imaging
Authors: Simon G.T. , Heng Y.M. , Ottensmeyer F.P. 
Published: June 2020

Electron energy loss spectroscopy (EELS) has become a significant technique for high resolution elemental microanalysis and mapping. Theoretically, quantitative analysis requires only one simple equation:Eqn.(1)where N is the number of atoms per unit area analysed; I(net)(a,δ) is the core loss intensity integrated over an energy range δ beyond the ionization edge and with a collection angle a; I(total) is the total intensity integrated beneath the whole spectrum; σ(a,δ) is the corresponding ionization cross section.To obtain I(net) according to current convention and some theoretical justification, the simplest way of removing the background beneath an ionization edge is simply fitting at least two pre-edge measurements to the equation of I=AE-r, where I is the intensity of electrons that have energy loss E; A and r are constants to be determined from the fitted pre-edge region. Several other methods have also been derived for better accuracy in specific applications.
High-resolution x-ray analysis of dislocation networks nn tilt boundaries
Authors: Michael J. R. , Lin C. H. , Sass S. L. 
Published: June 2020

The segregation of solute atoms to grain boundaries in polycrystalline solids can be responsible for embrittlement of the grain boundaries. Although Auger electron spectroscopy (AES) and analytical electron microscopy (AEM) have verified the occurrence of solute segregation to grain boundaries, there has been little experimental evidence concerning the distribution of the solute within the plane of the interface. Sickafus and Sass showed that Au segregation causes a change in the primary dislocation structure of small angle [001] twist boundaries in Fe. The bicrystal specimens used in their work, which contain periodic arrays of dislocations to which Au is segregated, provide an excellent opportunity to study the distribution of Au within the boundary by AEM.The thin film Fe-0.8 at% Au bicrystals (composition determined by Rutherford backscattering spectroscopy), ∼60 nm thick, containing [001] twist boundaries were prepared as described previously. The bicrystals were analyzed in a Vacuum Generators HB-501 AEM with a field emission electron source and a Link Analytical windowless x-ray detector.
Irradiation-induced mass loss effects at low temperature are dependent on specimen material
Authors: Lamvik M.K. , Davilla S.D. 
Published: June 2020

Low temperatures reduce the rate at which total mass or specific elements are lost from specimens during irradiation in electron microscopes. Many studies have shown such reductions when liquid nitrogen temperature was compared with room temperature. Some studies suggested an even greater benefit at liquid helium temperature. We recently found that there was a substantial reduction in the rate of mass loss from collodion when specimens were held at liquid helium temperature. The need for additional studies is illustrated by a comparison of collodion with albumin, which shows qualitative and quantitative differences in the response of these two materials to electron irradiation at liquid helium temperature.Collodion had distinct advantages as an initial specimen: There have been previous measurements, thus allowing comparison. Collodion is sensitive to radiation, so experiments could be completed efficiently. Most important was that collodion films could be made of uniform thickness, thus allowing the inital thickness to be used to monitor for accidental pre-exposure or unwanted material (like adsorbed water).
High-resolution electron spectrometers for molecular microanalysis
Authors: Ottensmeyer F. P. , Jiang X. G. 
Published: June 2020

The last decade has brought major advances in electron beam induced microanalytical capabilities, particularly with the utilization of energy loss electrons. These developments have been predicated primarily by the design and by the more ready commercial availabilty of better magnetic spectrometers, both for scanning transmission and fixed-beam transmission electron microscopy.Theoretical and experimental investigation of spatial resolution or localization possible for microanalysis and elemental mapping has indicated a potential of about 0.5 nm at an energy loss close to 100 eV, improving slowly with increasing energy loss. At lower energy loss the spatial resolution worsens due to an expected increase in impact parameter, but is still anticipated to be of the order of 1 nm at a 10 eV loss.Coupled with high spatial resolution is an experimentally observed very high sensitivity of detection and identification of a very small number of atoms at high concentration.
Analytical electron microscopy of fresh and vehicle-aged catalysts
Authors: Kim Sooho 
Published: June 2020

Automotive catalysts have a general loss of activity during aging, basically due to two principal deactivation mechanisms. One of them is thermally induced “sintering,” which results in catalytic surface area reduction. The other is chemically induced “poisoning,” which in part causes blockage of active metal sites. The conventional bulk techniques have indicated that various catalyst functions were affected differently by poisons and thermal damage; however, they generally did not provide detailed descriptions of the mechanisms of deactivation. Only analytical electron microscopy (AEM) can provide microchemical and microstructural information to gain a more thorough and fundamental understanding of catalytic deactivation.Fresh and vehicle-aged commercial automotive catalysts containing Pt, Pd, and Rh on alumina supports were prepared for AEM by a microtomy technique, which retains the spatial integrity of the catalyst pellet with uniform thickness. Then these AEM specimens were characterized in a transmission electron microscope (TEM) and in a dedicated scanning transmission electron microscope (STEM).
High-resolution TEM of precipitate plate growth by diffusional and displacive transformation mechanisms
Authors: Howe J. M. , Mahon G. J. 
Published: June 2020

Precipitate plates can grow by diffusional, displacive or coupled diffusional/displacive (for interstitial alloys) mechanisms of interfacial motion. In each case, it is necessary to characterize the atomic details of the structural and/or compositional changes which occur at the matrix/precipitate interface in order to fully understand the transformation mechanisms. High-resolution transmission electron microscopy (HRTEM) provides unique capabilities for obtaining such information. This is illustrated below by HRTEM studies of interfacial structure performed on precipitate plates which grow by diffusional and diffusionless mechanisms in Al-Li-Cu and Fe-Cr-C alloys, respectively.The growth of hexagonal T2 (Al2CuLi) precipitate plates on the {111{α f.c.c. matrix planes in an Al-2wt.%Li-1wt.%Cu alloy is an example of a diffusional transformation which requires substantial changes in both crystal structure and composition at the transformation interface. The growth of b.c.t. α martensite plates on the {252{γ f.c.c. austenite planes in a Fe-8wt.%Cr-1wt.%C alloy is more complicated than the T1 transformation crystallographically, but it is a good example of a diffusionless transformation which requires only a change in structure at the transformation interface.
Theory of plasmon diffuse scattering in dynamical calculations for RHEED: A method of introducing inelastic scattering in multislice theory
Authors: Wang Z. L. 
Published: June 2020

Multislice theory has been applied for investigating electron elastic scattering at crystal surfaces in reflection high-energy electron diffraction (RHEED). Quantitative analysis of RHEED intensity requires full dynamical calculation including multiple elastic and inelastic scattering. The purpose of this paper is to present a method for introducing plasmon diffuse scattering (PDS) in the multislice theory.Considering an electron travelling in medium b parallel to an interface with distance x from medium a, the kinetic energy of this electron after travelling distance z is given as:(1)Where eV0 is the incident energy of the electron; (-eU0) is the potential energy of the electron in the atomic potential of the solid; and (-Ui is the total energy-loss of the electron due to plasmon excitation, which can be calculated from the relativistic dielectric excitation theory as [2]:
Modified multislice theory for calculating the energy-filtered inelastic images in REM and HREM
Authors: Wang Z. L. 
Published: June 2020

Using a method introduced by Wang, the multiple plasmon diffuse scattering (PDS) can be included in dynamical calculation for reflection electron microscopy (REM) and high resolution electron microscopy (HREM). The calculated electron intensity distribution would be the combination of elastic and inelastic scattered electrons. In some experimental cases, it is desirable that the energy filtered inelastic image (EFIM) could be simulated. The purpose of this paper is to suggest a modified multislice theory for calculating the EFIM in REM and HREM.Considering an electron travelling in medium b with distance x parallel to an interface from medium a, due to the plasmon excitation, the wavelength of the electron is perturbed by its energy-loss during the propagation. The modified phase grating function (PGF) of a thin potential slice ▵z might be written as [1]:(1a)with(1b)
Analytic integration of contrast transfer functions
Authors: Rez Peter 
Published: June 2020

In high resolution microscopy the image amplitude is given by the convolution of the specimen exit surface wave function and the microscope objective lens transfer function. This is usually done by multiplying the wave function and the transfer function in reciprocal space and integrating over the effective aperture. For very thin specimens the scattering can be represented by a weak phase object and the amplitude observed in the image plane is1where fe (Θ) is the electron scattering factor, r is a postition variable, Θ a scattering angle and x(Θ) the lens transfer function. x(Θ) is given by2where Cs is the objective lens spherical aberration coefficient, the wavelength, and f the defocus.We shall consider one dimensional scattering that might arise from a cross sectional specimen containing disordered planes of a heavy element stacked in a regular sequence among planes of lighter elements. In a direction parallel to the disordered planes there will be a continuous distribution of scattering angle.
Identification of periodic structure characterized from amorphous support by simulation and processing techniques
Authors: O'Keefe Michael A. , Sattler Margaret L. 
Published: June 2020

High resolution electron images that suggest crystalline lattice fringes in a background of amorphous material are difficult to interpret. A new technique of image processing, referred to here as “background subtraction”, was recently developed to enhance images of such crystalline particles supported on amorphous substrates. However, the interpretation of exact crystalline surfaces on the particle was not straightforward. We have now applied this enhancement technique, previously used exclusively on experimental images, to simulated images of small crystals on amorphous substrates. Additionally, other commonly-used processing techniques are introduced as comparisons for the “background subtraction” method to point out its advantage in defining particle shape and internal structure.The model used for simulation consists of eight by eight units of anatase in [111] orientation (Fig. 1), enclosed in a “unit cell” of 56.8Å by 56.8Å (corresponding in size to 16 by 16 units of anatase). In addition we added various thicknesses of a structure of random SiO2units to this model to simulate the effects of an amorphous support.
An approach to damage-free analysis in Auger scanning microprobe
Authors: Mogami A. , Sekine T. 
Published: June 2020

Sample damage induced by electron bombardment is one of the biggest problems to be noticed in an Auger scanning microprobe with high spatial resolution.1) WHAT IS sample damage and 2) HOW TO MINIMIZE it are reported here.Fig. 1 shows the beam-induced damage on a silicon plate specimen. The silicon LVV peaks and secondary electron emission abruptly change within 1 sec. just after the ion sputtering is stopped, while such a rapid change may have been easily overlooked. Fig. 2 shows that the silicon oxide (coated to a thickness of 1,000 Å on a silicon plate) is gradually deoxidized under the beam. A peak characteristic of metallic state clearly appears 10 min. after electron bombardment. The maximum allowable dosage of electrons is roughly calculated to be approx. 10-6 coulomb/μm2 for this specimen.As an approach to damage-free analysis, beam brightness modulation (BBM) and the computer control system (CCS) with a light pen have been developed for the AUGER MICROPROBE, JAMP-10.