bluuebunny/crossref_metadata_2025_split huggingface dataset:
In-Situ TEM study of the role of secondary grain boundary dislo-cations in grain boundary migration and atom source/sink action
Authors: Babcock S. E. , Balluffi R. W. 
Published: June 2020

Over the past several years, a wealth of experimental evidence concerning the structure of simple grain boundaries (GBs) in metals has accumulated which suggests that the GBD/SU description of GB structure is applicable, at least at some level, to GBs in general. According to this model, high-angle GBs contain intrinsic arrays of grain boundary dislocations (GBDs) possessing Burgers vectors (b) which are translation vectors of an appropriate DSC-lattice, arranged in a network which is consistent with Frank's formula.A special property of secondary GBDs (SGBDs), i.e., GBDs possessing bs which are not lattice vectors of either of the adjoining crystals, is that a step in the boundary plane is often associated with their core.
Substructure Of needle-shaped precipitates in An Al-Ge alloy
Authors: Dahme U. , Westmacot K.H. 
Published: June 2020

Dilute Al-Ge alloys provide a good model for metal-semiconductor interface studies because clean interfaces in different orientations can be grown by precipitating Ge from the A1 terminal solid solution. A great variety of orientation relationships and morphologies have been observed in this alloy, including plates, laths, needles and tetrahedral Needle precipitates along <100> A1 which are invariably twinned form in abundance during low-temperature aging. Since <110> Ge is exactly parallel to the needle axis, high resolution microscopy allows direct and accurate analysis of the precipitate orientation relationship, morphology, interface and defect structure.It was reported earlier that the particle morphology usually conformed to the symmetry of its orientation relationship with the matrix. This rule was broken only by some of the twinning defects observed. In the present contribution we focus attention on the substructure formed by these twins and their relationship to the particle morphology.
Palladium silicides above the Pd2Si ⇋ PdSi transformation temperature
Authors: Vanderwalker D. M. 
Published: June 2020

There is considerable interest in the formation of intermetallic compounds at metal-semiconductor contacts. The interfacial structure controls the barrier height. In the Pd-Si system, thin film experiments were performed over a range of temperatures. Pd2Si was found in samples annealed at temperatures below 810°C. Above 810°C, Pd2Si was observed to transform to PdSi. Pd2Si seeds were found to form in amorphous Pd80Si20 annealed at 175°C. This paper examines the palladium silicides formed just above the Pd2Si ⇋ PdSi transformation temperature.A Pd layer was evaporated on Si wafers at the (111) and (001) orientation in a vacuum pressure less than 10-6 torr. The samples were encapsulated in vacuum tubes before annealing at 825°C for one hour. TEM specimens were prepared by mechanical, then chemical thinning from one side with a 6/7 nitric acid 1/7 hydrofloric acid solution. The TEM was performed on the JEM 200CX and Phillips 400.
A distorted 6H structure in an A1-Li-Cu-Mg-Zr- alloy
Authors: Zhang J. P. , Tsurata C. , Marks L. D. 
Published: June 2020

The powder extracted from a Al-base alloy containing Li, Cu, Mg and Zr was examined in a H9000 electron microscope equipped with ultra-high resolution polepieces having Cs = 0.9mm at 300 KV for HREM studies.Figure 1 is a typical electron diffraction pattern of 6H structure: spots are grouped as six neighbours along c direction. For 00ℓ when ℓ = 6n (n = 0, 1, …) the diffraction spots occur with strong intensities while for 10ℓ, the reflections are almost extinct when ℓ = 6n. The stacking sequence of (001) planes is ABCACB composed by 3R, ABC, and anti 3R, ACB, twinned structures with a = 0.27 nm , c = 1.52 nm. Figure 2 is a structure image in the same direction of Fig.l, which shows the (001) stacking clearly. No twinned structure was observed because the stacking sequence is modified to ABCAB'B, where the C of anti 3R is changed to B’ that is close to B but different.
Transmission electron microscopy of polymers
Authors: Thomas Edwin L. 
Published: June 2020

Transmission electron microscopy continues to play a major role in micro-structural characterization of polymers. Additionally, as evidenced by the special symposium on electron crystallography at this EMSA meeting, electron diffraction, as applied to polymer crystals, is also a vigorous area of research. Because many of the interesting morphological features of polymer systems are at and below the micron scale, TEM is a most fruitful technique. Applications range from simple assessment of dispersed phase particle size in blends to HREM molecular imaging of defects in crystals. Thus polymer scientists probe structures over about 4 orders of magnitude in size, and the versatility of the TEM in such endeavors is evident from its essentially ubiquitous appearance in all modern physical sciences laboratories.While there are a host of standard and advanced texts on the application of TEM to metals and to biology, there are only a few review papers on polymer microscopy and one just-published book.
Quantitative Crystal Structure Analysis In The Electron Microscope
Authors: Dorset Douglas L. 
Published: June 2020

Electron crystallography is a term which has emerged in the past few years to describe the quantitative structure analysis of microcrystalline preparations in the electron microscope. The field represents the confluence of two techniques, i.e. the ultramicroscopic capabilities of the electron microscope coupled with analytical techniques long in use by X-ray crystallographers. In the area of organic materials, the most visible success of the technique to date has been in the structure analysis of thin protein microcrystals typically to ca20 Å resolution but sometimes out to e.g. 7 Å and, in this field, there has been considerable effort by an increasing number of laboratories.Although the electron crystallography of small organic molecules and linear polymers has a much longer history than the application to globular proteins, one cannot cite an overwhelming enthusiasm for this technique, despite its promise as a probe for molecules which are not easily crystallized to sample sizes useful for single crystal X-ray diffraction measurements.
Visualization of continuous crystal formation in high-density polyethylene
Authors: Brady J. M. , Thomas E. L. 
Published: June 2020

Though chemically simple, polyethylene has proven to be an extremely versatile polymer. Its physical and mechanical properties can be made to cover a broad range of requirements by varying processing, branching, and the molecular weight of the material. In particular, ultrahigh modulus polyethylene (tensile moduli exceeding 200 Gpa) has been made by solid state extrusion (SSE) at 110 C followed by post drawing (PD) at 125 C. The objective of the following study was to investigate the evolution of structure during the SSE/PD process, and to identify those morphological features which give rise to ultimate properties.The SSE/PD process was mimicked here by deforming thin films of HDPE at high temperature (129 C). High density polyethylene (HDPE) of Mw = 200,000 and Mw /Mn =7-13 was used. As-processed films were highly oriented and displayed a single crystal-like textured shish-kebab morphology.
Structure-property relations of liquid crystalline polymers
Authors: Sawyer Linda C. 
Published: June 2020

Recent liquid crystalline polymer (LCP) research has sought to define structure-property relationships of these complex new materials. The two major types of LCPs, thermotropic and lyotropic LCPs, both exhibit effects of process history on the microstructure frozen into the solid state. The high mechanical anisotropy of the molecules favors formation of complex structures. Microscopy has been used to develop an understanding of these microstructures and to describe them in a fundamental structural model. Preparation methods used include microtomy, etching, fracture and sonication for study by optical and electron microscopy techniques, which have been described for polymers. The model accounts for the macrostructures and microstructures observed in highly oriented fibers and films.Rod-like liquid crystalline polymers produce oriented materials because they have extended chain structures in the solid state. These polymers have found application as high modulus fibers and films with unique properties due to the formation of ordered solutions (lyotropic) or melts (thermotropic) which transform easily into highly oriented, extended chain structures in the solid state.
Electron microscopy of polymer blends
Authors: Briber Robert M. 
Published: June 2020

Polymer blends have come to play an increasingly important role in materials science as the need for polymeric materials with wider ranging properties has developed. Data will be presented in this paper on two polymer blend systems that have benefited from the use of electron microscopy in understanding the complex morphologies than can occur in polymer systems.Blends of Poly(vinylidene fluoride) and poly(ethyl acrylate)Poly(vinylidene fluoride) (PVF2) and poly(ethyl acrylate) (PEA) form a miscible, single phase melt over the composition range of 50% PVF2 (by weight) and less. The melt exhibits phase separation upon heating to 10-50°C above the observed melting point of PVF2, depending on the composition, PVF2 is a semicrystalline polymer, while PEA is an amorphous polymer. The fact that PVF2 is compatible in the melt with PEA has allowed for detailed morphological studies of single crystal lamellae and spherulites of the α crystal form of PVF2 grown at temperatures very close to those found in conventional melt crystallization.
Optimizing the collector solid angle for the low-loss electron image in the Scanning Electron Microscope
Authors: Wells Oliver C. 
Published: June 2020

The low-loss electron (LLE) image in the scanning electron microscope (SEM) is formed by collecting backscattered electrons (BSE) that have lost less than a specified energy. Compared to the secondary electron (SE) image, these images are less affected by specimen charging and show the surface topography clearly when examining uncoated photoresist. However, LLE images sometimes contain dark shadows caused by the limited solid angle of the LLE detector. Here, we describe a way to position the sample (with a given LLE detector) so as to reduce these shadows as far as possible.The SEM was a Cambridge S-250 Mk. III with a tungsten filament. An experimental LLE detector was added. The SE image was obtained using the SE detector ordinarily present in the SEM.The LLE detector is shown in Fig. 1. The specimen is mounted close to the lens in the SEM with a glancing angle of incidence of 30°.
Freeze-fracture of cell nuclei for high-resolution SEM and deep-etch tem
Authors: Haggis G.H. 
Published: June 2020

The results reported in this paper form a direct extension of the work of Heuser and Kirschner. These authors permeabilized cultured fibroblasts with Triton X-100 prior to rapid freezing, freeze-drying and rotary platinum coating for TEM viewing. We have permeabi1ized 3T3 cells in a stabilization buffer similar to that used by Heuser and Kirschner, rapidly frozen and fractured the permeabilized cells, rotary coated the preparations with platinum after both deep etching and critical-point drying and viewed them by both TEM and high-resolution SEM. By fracturing the cells we obtain an internal view of the nucleus as well as of the cytoplasm.The 3T3 cells were cultured on a film of fibrin 20 μm thick (for reasons described below). The cells were permeabi1ized at room temperature for 15 min with 0.5% Triton X-100 in Bershadsky buffer (50 mM imidazole 50 mM KC1, 0.5 mM MgCl2, 1 mM EGTA, 0.1 mM EDTA, 1 mM mercaptoethanol, 4M glycerol at pH 6.7).
Quantitative ultrastructural reconstruction of small regions within large volumes by correlative light and high voltage electron microscopy of serial 0.25-0.50 μm sections
Authors: Rieder Conly L. , Miller Frederick J. , Davison Edwin , Bowser Samuel S. , Lewis Kirsten , Sluder Greenfield 
Published: June 2020

In this abstract we Illustrate how same-section correlative light and high voltage electron microscopy (HVEM) of serial 0.25-0.50-μm sections can answer questions which are difficult to approach by EM of 60-100 nm sections.Starfish (Pisaster and Asterlas) eggs are fertilized at meiosis I when the oocyte contains two maternal centrosomes (e.g., asters) which form the poles of the first meiotic spindle. Immediately after fertilization a sperm aster is assembled in the vicinity of the male pronucleus and persists throughout meiosis. At syngamy the sperm aster splits to form the poles of the first mitotic spindle. During this time the functional and replicative properties of the maternal centrosome, inherited from the last meiotic division, are lost. The basis for this differential stability, of male and female centrosomes in the same cytoplasm, is a mystery.
Correlative ultrastructure and immunocytochemistry in small round cell tumors of childhood
Authors: Tsokos M. , Triche T.J. 
Published: June 2020

Conventional methods of pathologic evaluation of the undifferentiated solid tumors of childhood, often referred to as “small round cell tumors”, have been notoriously unreliable. Prior to the advent of effective therapy, this was of little consequence. Current treatment methods require precise categorization of these tumors, as tumor response shows wide variation, especially when inappropriate chemotherapeutic agents or radiation therapy are employed. The combination of transmission electron microscopy (TEM) and correlative immunocytochemistry (ICC) has proved to be a powerful tool in deriving precise diagnoses.The common small round cell tumors of childhood include sarcomas (especially undifferentiated rhabdomyosarcoma), lymphomas (especially lymphoblastic and large cell), neural tumors (neuroblastoma and a variety of apparently related neoplasms), and particularly Ewing's sarcoma, an enigmatic tumor of inapparent histogenesis with which all the above are compared. The treatment and prognosis of each of these groups is quite different, and we have attempted to reliably distinguish each from the other by ultrastructural and immunocytochemical criteria.
200kv superconducting cryo electron microscope
Authors: Iwatsuki M. , Kokubo Y. , Harada Y. , Lehman J. 
Published: June 2020

In recent years, the electron microscope has been significantly improved in resolution and we can obtain routinely atomic-level high resolution images without any special skill. With this improvement, the structure analysis of organic materials has become one of the interesting targets in the biological and polymer crystal fields.Up to now, X-ray structure analysis has been mainly used for such materials. With this method, however, great effort and a long time are required for specimen preparation because of the need for larger crystals. This method can analyze average crystal structure but is insufficient for interpreting it on the atomic or molecular level. The electron microscopic method for organic materials has not only the advantage of specimen preparation but also the capability of providing various information from extremely small specimen regions, using strong interactions between electrons and the substance. On the other hand, however, this strong interaction has a big disadvantage in high radiation damage.
Imaging of the crotoxin crystal in vitreous ice at 3.9 Å resolution
Authors: Degn L. L. 
Published: June 2020

The crotoxin complex is a 24,500 dalton neurotoxic protein isolated from the venom of the Brazilian rattlesnake Crotalus durissus terrificus. The crotoxin complex crystallizes as thin crystals suitable for high resolution 3-D reconstruction by electron crystallographic analysis. High resolution imaging of an untilted crotoxin complex crystal embedded in glucose has been reported. Presented here is high resolution (3.9 Å) imaging of an untilted crotoxin complex crystal embedded in vitreous ice.Several technical problems are involved in the collection of high resolution electron crystallographic data for 3-D reconstruction. First, the specimen should be as flat as possible on the grid since bending due to specimen preparation or due to beam-induced movement may cause smeared reflections in electron diffraction patterns or optical diffractograms, a phenomenon that is particularly noticeable in highly tilted specimens.
The Three-dimensional structure of frozen-hydrated nudaurelia capensis β virus
Authors: Olson N. H. , Baker T. S. , Mu Wu Bo , Johnson J. E. , Hendry D. A. 
Published: June 2020

Nudaurelia capensis β virus (NβV) is an RNA virus of the South African Pine Emperor moth, Nudaurelia cytherea capensis (Lepidoptera: Saturniidae). The NβV capsid is a T = 4 icosahedron that contains 60T = 240 subunits of the coat protein (Mr = 61,000). A three-dimensional reconstruction of the NβV capsid was previously computed from visions embedded in negative stain suspended over holes in a carbon film. We have re-examined the three-dimensional structure of NβV, using cryo-microscopy to examine the native, unstained structure of the virion and to provide a initial phasing model for high-resolution x-ray crystallographic studiesNβV was purified and prepared for cryo-microscopy as described. Micrographs were recorded ∼1 - 2 μm underfocus at a magnification of 49,000X with a total electron dose of about 1800 e-/nm2.
Analytical Electron Microscopy in human pathology
Authors: Shelburne J.D. , Ingram P. 
Published: June 2020

Analytical electron microscopy and related microprobe techniques such as ion microscopy and laser microscopy have been widely used in scientific investigations of many types. This presentation will review the rapidly expanding body of scientific literature on the application of microprobe techniques solely to problems in human pathology. With this goal in mind the presentation will focus on studies that demonstrate potential for microchemical microscopy in diagnostic and clinical pathology, and not on studies that are primarily research oriented.Also, it is not the purpose of this presentation to discuss articles primarily devoted to secondary electron imaging - the emphasis is on analytical, not morphological, techniques. A review of sample preparation techniques applicable to the analytical study of human tissue is included, as is also a brief discussion of possible artifacts from these techniques.
STEM/EDS microanalysis of smoker lungs and ferruginous bodies
Authors: Lloyd J. K. , Harris J. H. , Nichols N. T. 
Published: June 2020

Previous studies have used digestion techniques with SEM/EDS to identify foreign material in lungs, These studies have identified elements with inclusions of lung tissue exposed to cigarette smoke, and clinical cases having ferruginous bodies. We have established a protocol to examine fixed lung tissue using x-ray microanalysis with STEM. Our technique allowed both localization and elemental analysis of foreign material in tissue. In the present study lung tissue from cigarette smokers and bronchial washings containing ferruginous bodies were examined.Histological slides of smoker lung tissue were examined to locate dark granular inclusions in cells and the interstitium. Cytology cell block slides of bronchial washings depicting ferruginous bodies were also selected. After locating these granules and bodies, tissues were carefully removed from the paraffin blocks, deparaffinized, and embedded in Spurr. Sections ranging in thickness from 180nm - 500nm were cut with a diamond knife and collected on nylon grids.
X-Ray microanalytical demonstration of osteogenesis after hydroxylapatite/plaster frontal sinus cranioplasty in cats
Authors: Giammara B. , Rawlings C. , Ovelmen-Levitt J. , Wilkins R. , Georgiade N. , Hanker J. 
Published: June 2020

The repair of cranial defects with methyl methacrylate is generally successful with the exception of the frontal sinus where infection is a problem due to the connection of the sinus with the nasal cavity.Composite hydroxylapatite/plaster implants have been used successfully for various jawbone defects in many experimental animals and patients. The plaster prevents the scatter of the hydroxylapatite (HA) particles during, and migration after, the implantation procedure. It also facilitates tailoring of the implant to fit the defect. The plaster is resorbed in a period of weeks and replaced at the same rate by infiltrating fibrovascular tissue which maintains the shape and integrity of the implant. Postoperative infection is rare, and then limited almost exclusively to cases where it had been observed preoperatively. It was, therefore, of interest to study HA/plaster for frontal sinus cranioplasty in cats.
Two distinct negative staining patterns of halobacterium cell envelopes
Authors: Kessel Martin , Loren Buhle E. , Cohen Simone , Aebi Ueli 
Published: June 2020

The cell walls of Halobacteria are comprised of a 200,000MW sulphated glycoprotein, and by shadow casting are seen as a periodic hexagonal lattice of morphological units with a center to center spacing of approximately 140A. Preparations ot virtually salt tree envelopes from Halobacterium volcanii isolated from the Dead Sea, obtained by freezing and thawing the cells and suspension in 10mM CaCl2, have enabled high resolution analysis of the wall morphological units by negative staining.Envelopes of H. volcanii negatively stained with 1% uranyl acetate or 0.75% uranyl formate both at pH 4.5, have consistently resulted in two different images irrespective ot the stain used: a more prevalent “honeycomb” appearance of strong stain accumulating centers surrounded by regions ot stain exclusion (fig. 1 and fig. 3B); and a less common “true” negative staining with stain excluding rings (morphological units) and their stain accumulating centers lying in pools ot stain (Fig. 2 and 3A).
Application of cross correlation to HREM images of surfaces
Authors: Luzzi D. E. , Marks L. D. , Buckett M. I. 
Published: June 2020

As the HREM becomes increasingly used for the study of dynamic localized phenomena, the development of techniques to recover the desired information from a real image is important. Often, the important features are not strongly scattering in comparison to the matrix material in addition to being masked by statistical and amorphous noise. The desired information will usually involve the accurate knowledge of the position and intensity of the contrast. In order to decipher the desired information from a complex image, cross-correlation (xcf) techniques can be utilized. Unlike other image processing methods which rely on data massaging (e.g. high/low pass filtering or Fourier filtering), the cross-correlation method is a rigorous data reduction technique with no a priori assumptions.We have examined basic cross-correlation procedures using images of discrete gaussian peaks and have developed an iterative procedure to greatly enhance the capabilities of these techniques when the contrast from the peaks overlap.
Potential use of Si-labeled colloidal gold for localization of F-actin
Authors: Bozzola J. J. , Peterson R. N. , Kamaph U. , Russell L. , Shriver J. 
Published: June 2020

Filamentous actin has been localized in numerous plant and animal species using various immunocytochemical procedures as well as a decoration technique using myosin subfragment 1 (SI). In the latter case, the long F-actin strands appear as herringbones with stacked arrowheads of SI pointing in the same direction. Unfortunately, when the actin filaments occur as shorter oligomers, it may be difficult to discern this pattern against a complex background. Using immunocytochemical procedures, variabilities in labeling patterns encountered may be attributed to the use of polyclonal antibodies or to antibody specificities for various subclasses of actin. In an attempt to localize short segments of F-actin without the use of antibodies, we labeled colloidal gold particles with purified SI.In order to evaluate the efficacy of this procedure, purified SI and partially purified F-actin were obtained from rabbit skeletal muscle.