bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzymatic digestion of seeds as a preparation technique for Scanning Electron Microscopy
Authors: Scott Randy , Ocumpaugh W. R. 
Published: June 2020

The study of the microstructure of seed is an area of interest. Work in progress was confused by the difficulty in determining what part of the monocot seed was embryo and what part was endosperm. Routine histological facilities were not available and the imaging of the scanning electron microscope was desired.The image seen on the left was prepared by simply cutting, mounting and coating the seed. This micrograph presents a puzzle to those of us who are not very familiar with the structure of seeds. Note, some organization is in evidence in the long section down the middle of a grass seed. With imagination, it might be thought that the embryonic leaflets can be seen. The rootlet and other structure presents a confusing display.
Probe size and 5th-order aberration
Authors: Shao Zhifeng 
Published: June 2020

A small electron probe has many applications in many fields and in the case of the STEM, the probe size essentially determines the ultimate resolution. However, there are many difficulties in obtaining a very small probe.Spherical aberration is one of them and all existing probe forming systems have non-zero spherical aberration. The ultimate probe radius is given byδ = 0.43Csl/4ƛ3/4where ƛ is the electron wave length and it is apparent that δ decreases only slowly with decreasing Cs. Scherzer pointed out that the third order aberration coefficient always has the same sign regardless of the field distribution, provided only that the fields have cylindrical symmetry, are independent of time and no space charge is present. To overcome this problem, he proposed a corrector consisting of octupoles and quadrupoles.
Analytical Electron Microscopy of α-Al2O3 implanted with iron
Authors: Sklad P. S. 
Published: June 2020

Ion implantation has become an accepted method for achieving a wide variation in the near surface microstructure and properties of many materials. A number of recent studies have concentrated on modifying the properties of Al2O3. However, the effectiveness of such surface modification is strongly dependent on the microstructural development which takes place in the implanted region during post-implantation annealing. Analytical electron microscopy (AEM) techniques are unique in that they allow direct observation of changes in microstructure and composition which are produced during such anneals.Single crystals of α-Al2O3 in the basal orientation were implanted with 160 keV Fe ions to a dose of 4 x 1016 or 1 x 1017 ions/cm2 with a dose rate of ∼2 amps/cm2. The implantations were carried out at room temperature. A number of specimens were subsequently annealed for 1 h at temperatures in the range 973 K to 1773 K in flowing oxygen.
Aem analysis of defects in processed Si wafers
Authors: Lewis Nathan , Hall Ernest L. , Hall Robert N. 
Published: June 2020

The analytical electron microscope is particularly well suited for the characterization of many types of defects observed in semiconductor materials. One type of common defect which has been shown to occur in some devices is an electrically-active rod defect which has a detrimental effect on some properties. In the present AEM investigation Si devices which exhibited a significant degradation in certain electrical properties (excess junction leakage) were examined in order to ascertain the cause of this phenomenon.The starting material in the process was n-type (100) silicon wafers. The initial processing step was the growth of 200nm of LPCVD SiO2. During the processing sequences wafers were subjected to temperatures up to 900°C.
Glide of extended dislocation in III-V compounds
Authors: De Cooman B.C. , Carter C.B. 
Published: June 2020

The study of dislocation dynamics has until recently been restricted to relatively high temperatures and low stresses due to the the brittle nature of most semiconductors. Although much is already known for this deformation regime, there is little information from controlled deformation at the low temperatures (i.e., T< 0.5Tm) and high stresses (τ≫ 10 MPa). Deformation of III-V compounds under such conditions has shown the following characteristics:a. High-stress deformation experiments give rise to well-defined dislocation configurations, which makes the study of doping effects on dislocation mobility directly visible. In addition, individual partial dislocations can be observed using weak-beam microscopy.
Cathodoluminescence for characterization of quantum wires and discs
Authors: Lin P. S. D. , Dobisz E. A. , Kash K. , Scherer A. , Craighead H. G. , Tell B. , Harbison J. P. 
Published: June 2020

Detection of cathodoluminescence(CL) in an scanning electron microscope(SEM) is a powerful technique in the study of novel nanometer size structures in semiconductors. In the SEM, the electrons can be focused into a nanometer probe and one can choose to excite either a single structure or multiple structures. Geometric parameters can be measured in-situ from the secondary(or transmitted) electron image. The carrier injection level is uniform and insensitive to adsorbed surface contamination. We demonstrate in this report the potential of CL in the study of nanometer size quantum-well wires and discs.The experimental setup (Fig. 1) includes a scanning electron microscope, a liquid helium cooled cryostat (from Oxford Instruments) which cools both the ellipsoidal mirror and the sample, and an optical spectrometer equipped with a silicon diode array detector controlled by a multi-channel analyzer (TN 1710).
The microstructure of ionized cluster beam aluminum deposited on (100) silicon and (111) silicon
Authors: Madden Michael C. , Tracy Bryan M. 
Published: June 2020

Ionized cluster beam (ICB) is a novel method of depositing thin films. The apparatus consists of a graphite crucible containing the material to be deposited, in this case aluminum, with a small hole in its top. The crucible is heated under vacuum. The atomic clusters that emerge from the hole are showered with electrons, then accelerated through a potential of several kilovolts before striking a substrate. Aluminum films prepared in this manner have been reported to have several interesting properties, including improved spiking resistance and improved electromigration resistance.Aluminum samples were prepared on (100) and (111) silicon substrates. 3mm discs were cut uItrasonicaIly, mechanically thinned to 100 μm, chemically etched with HF-HNO3 (1:3), and ion milled to perforation. All thinning was done from the substrate side of the sample. Samples were then examined in a JEOL 1200EX TEM operated at 120 kV.
A method of asbestos fiber counting using transmission electron microscopy
Authors: Ghosh A. , Jenniss S. W. , Shahiea S. I. 
Published: June 2020

As the health hazard posed by small asbestos fibers in ambient air has become increasingly evident in recent years, so too has the need increased for a means to accurately and precisely measure the concentration of these fibers (1,2,3,4). The goal of this study was to develop a standard procedure for sample preparation and estimation of asbestos fiber mass using Transmission Electron Microscope (TEM) which would yield highly precise and accurate data.The proposed method under evaluation required air samples be taken on membrane filters and carbon coated in a vacuum evaporator. Three randomly punched 3 x 3 mm sections of the coated filters were placed on 200 mesh carbon-coated EM grids and washed with acetone vapor in a condensation washer, carefully controlling the solvent reflux height at 4 - 5 mm above the cold finger, to remove the filter material. The processed samples were then analyzed by TEM.
Energy-dispersive spectroscopy of melanosomes in horse hair follicles
Authors: Swafford J. R. , Woolf C. M. 
Published: June 2020

As part of a study on the genetics of coat color in the Arabian horse, we initiated studies on the ultrastructure of melanosomes produced by melanocytes in the hair follicles at the base of black and reddish-colored hairs. The purpose was to determine if a correlation exists between hair color and the presence of specific types of melanosomes.Melanosomes can be characterized by shape and chemical composition. The biochemical pathway from tyrosine to melanin is branched with different paths leading to the production of eumelanin (black pigment) and pheomelanin (yellowish-red pigment). The major isomer of eumelanin is dopaquinone and that of pheomelanin is 5-S-cysteinyldopa. Hence, sulfur is absent in eumelanin but present in pheomelanin. Eumelanogenesis leads to ellipsoidal melanosomes; pheomelanogenesis leads to spherical melanosomes. However, classification of melanosomes solely on the basis of their shape may be misleading under certain conditions.
A comparative STM and TEM study of polycarbonate substrates
Authors: Reifenberger R. , Baro A. M. , Vazquez L. , Bartolami A. , Garcia N. , Goldberg H. A. , Kohn R. , Chen R. T. , Sawyer L. C. 
Published: June 2020

Scanning tunneling microscopy (STM) is the newest method that allows real space imaging of surfaces on a scale extending to atomic dimensions. The STM technique was developed by C. Binnig, H. Rohrer, and co-workers at IBM Zurich laboratories and is notable for its ability to image a wide range of materials under a variety of different conditions. The technique has received considerable attention for its ability to provide information about postions of individual surface atoms with unprecendented three-dimensional resolution.The physical basis for the STM is a quantum mechanical electron tunneling from a sharp tip to a conducting substrate. The exponential dependence of the tunneling current with the tip-to-sample separation allows a measurement of vertical position differences smaller than ca. 0.01 nm often with a lateral resolution of better than ca. 0.2 nm. By rastering the tip across a sample surface while monitoring the tunneling current, a three dimensional topographic image of the surface can be obtained.
Direct visualization of microstructure deformation processes in polyethylene
Authors: Adams W.W. , Yang D. , Thomas E.L. 
Published: June 2020

Deformation processes of semicrystalline polymers are highly dependent on microstructure and its orientation, as for example in the different zones of spherulites. The elucidation of the deformation mechanisms is a complex problem, primarily due to the hierarchy of structural features present. Our approach to the determination of the important morphological processes occuring during deformation is to simplify both the sample morphology and the applied stress. The production of near single-crystal texture thin polyethylene (PE) film was made possible by modification of Petermann's method to prepare highly chain axis oriented and planar textured films of high density (HD) PE, in both as-drawn (AD) and annealed (AN) forms. These single crystal texture films were ideal for in situ microscopic deformation studies.HDPE (Marlex 6003 from Phillips Chemical) was melt-drawn from a glass slide at 120°C to form AD films, some of which were then annealed on glycerol at 128°C for two hours.
Grain boundary imaging by digital reconstruction of HREM lattice images of poly(P-phenylene benzobisthiazole) fibers
Authors: Martin David C. , Boudet Alain , Thomas Edwin L. 
Published: June 2020

Poly(p-phenylene benzobisthiazole) (PBT) is a rigid-rod polymer of interest for high-strength fibers and other applications including nonlinear optical behavior. PBT fibers are formed by coagulation into water from solutions of the molecule in strong acid. Because of the high orientation and strength of these fibers, the nature of boundaries and defects between crystalline regions is of particular scientific and technical concern.The crystal structure of PBT fibers has been investigated by electron and X-ray diffraction. It has been found that the unit cell is monoclinic with a =.59 nm, b =.36 nm, c =1.249 nm, gamma =95.5 degrees. The molecules are oriented along the c axis of the unit cell and exhibit axial translational disorder in both the [100] and [010] directions.PBT is resistant to electron beam damage, having a critical dose of 1.6 Coulombs/cm2 at 100 kV and room temperature.
The morphology and deformation behavior of poly(butylene terephthalate) blends
Authors: Hobbs S.Y. , Dekkers M.E.J. , Watkins V.H. 
Published: June 2020

Impact-modified blends of BPA polycarbonate (BPAPC) and poly(butylene terephthalate) (PBT) are being used to an increasing extent in engineering applications requiring superior low temperature toughness (e.g., automotive bumpers). In order to optimize the performance of these materials in such demanding situations, it is essential to develop a thorough understanding of the factors affecting their microstructure and deformation behavior. To be successful in this endeavor, an interdisciplinary effort involving detailed microscopic characterization, sophisticated mechanical testing, and careful analytical studies is required. Although some work of this type has appeared in the literature (1,2) together with more fundamental research on BPAPC/PBT miscibility (3-6), major questions with respect to phase segregation, distribution of blend components, and morphological changes which occur during deformation remain.In response to these issues, a more complete investigation of the microstructure and deformation characteristics of several PBT blends containing various combinations of polycarbonate and impact modifier was recently carried out in our laboratory.
Resolution and measurement in the scanning electron microscope
Authors: Postek Michael T. 
Published: June 2020

The term ultimate resolution or resolving power is the very best performance that can be obtained from a scanning electron microscope (SEM) given the optimum instrumental conditions and sample. However, as it relates to SEM users, the conventional definitions of this figure are ambiguous. The numbers quoted for the resolution of an instrument are not only theoretically derived, but are also verified through the direct measurement of images on micrographs. However, the samples commonly used for this purpose are specifically optimized for the measurement of instrument resolution and are most often not typical of the sample used in practical applications.SEM RESOLUTION. Some instruments resolve better than others either due to engineering design or other reasons. There is no definitively accurate definition of how to quantify instrument resolution and its measurement in the SEM.
The SEM interpretation of fractal surfaces
Authors: Christian Russ J. , Russ John C. 
Published: June 2020

The concept of a fractal dimension, a non-integer value greater than the traditional 1 (for a line) or 2 (for a surface) that we are accustomed to in Euclidean geometry, was first popularized by B. B. Mandelbrot. From its beginning as a mathematical construct and curiosity, it quickly developed some very practical uses, and now in several branches of science there are fractal interpretations of data that show much promise.Briefly, a fractal line (which has a dimension greater than 1 and less than 2) is not straight, but “crinkly” so that its length exceeds the distance between its endpoints. Further, for an ideal fractal this same degree of irregularity is present at any magnification, so that as we zoom in closer to the line, it continues to reveal more detail (as a function of the resolution of our instrument) but there is no internal way to judge the magnification.
Ultrastructural analysis of human tumors with immunohistochemical correlations
Authors: Erlandson Robert A. 
Published: June 2020

Transmission electron microscopic (TEM) studies and, more recently, immuno-histochemical (IHC) procedures using newly developed monoclonal antibodies have made significant contributions to the diagnosis of poorly differentiated tumors and to the histogenetic analysis of cytologically complex neoplasms. In this report we will show how TEM and IHC studies confirm a suspected diagnosis of amelanotic malignant melanoma and reveal that the so-called “mesenchymal” cells found in benign pleomorphic adenomas are actually metaplastic myoepithelial cells. Epithelial differentiation of mesenchymal tissues is exemplified by TEM and IHC evaluation of synovial and epithelioid sarcomas, respectively.The ultrastructural diagnosis of amelanotic malignant melanoma requires the recognition of premelanosomal organelles or aberrant melanosomes in the cytoplasm of the neoplastic cells. Ovoid or ellipsoidal vesicles with a characteristic internal inclusion consisting of rigid parallel fibrils (pseudo-crystalline substructure) or coiled or pleated (zig-zag) fibrils (Figs. 1&2) also known as stage II melanosomes are diagnostic.
Clq nepropathy: A case report of a newly described glomerularopathy
Authors: Price George , Cerezo Lizardo 
Published: June 2020

A distinctly new pathologic entity that causes steroid resistant nephrotic syndrome has been described by Jennette and Hipp. Clq nephropathy gets its name from the strong positivity of Clq localized by immunofluorescence. Reactions for C3, IgG and IgM are present, with a mild reaction for IgA occuring in some cases.The ultrastructural features of Clq glomerular nephropathy (Clq GN) and systemic lupus erythmatosis glomerular nephropathy (SLE GN) are strikingly similar in that they both demonstrate mesangial cell proliferative activity, mesangial dense deposits, and subendothelial or subepithelial dense deposits. One ultrastructural difference between Clq GN and SLE GN is the lack of endothelial tubuloreticular inclusions in Clq GN.The most interesting aspect of Clq GN is that although the glomerular changes resemble SLE GN by light microscopy and electron microscopy, these patients lack clinical or serological evidence for SLE. Specifically, serological tests for ANA, anti-DNA, and LE are all negative in Clq GN patients.
Computer graphics 3-D reconstruction of intracytoplasmic lumina in breast carcinoma
Authors: Song M.J. , Hussain M. , Marko M. , Song C.Y. , Parsons D.F. 
Published: June 2020

Intracytoplasmic lumina occur mainly in infiltrating lobular carcinoma. Their identification in large number provides additional support for the breast origin of a metastatic tumor. Although intracytoplasmic lumuina were originally characterized with the electron microscope, they can be identified by light microscopy. Recently their usefulness in histopathologic diagnosis has received attention. However, their role in cell physiology or pathology remains unknown. It is not known whether they communicate with the exterior of the cell. This information might suggest a possible function. In attempting to seek communicating channels, we have studied infiltrating lobular carcinoma of signet-ring cell type in two patients.All tumor biopsy specimens from the breast and associated lymph nodes were taken under local anesthesia. Specimens for LM were fixed in phosphate-buffered 10% formaldehyde and processed by paraffin embedding, hematoxylin-eosin stains, and mucicarmine stain.
Eponate 12, a new epoxy resin: Comparisons with EPON 812 and observations on its use for general biological electron microscopy
Authors: Mascorro J.A. , Kirby G.S. 
Published: June 2020

Many epoxy resins have been introduced during the last several years as replacements for Epon 812 since the Shell Chemical Company discontinued production of this popular embedding resin. In a past study, the present investigators examined several of the “replacement” resins for physical characteristics such as viscosity, flow rate, density, mass weight, and hardness of the polymerized medium. In addition, other equally important parameters including sectioning and infiltrating character as well as stain-ability and section strength subsequent to beam and vacuum conditions also were evaluated. The present work follows a similar rationale and seeks to determine this same information for Eponate 12, an epoxy resin designated as a true generic replacement for the formerly available Epon 812 product.For purposes of physical comparisons, Eponate 12 was tested against a sample of original Shell Epon 812 still maintained in our laboratory.
Three Dimensional structure and organization of diploid chromosomes by optical section microscopy
Authors: Agard David A. , Hiraoka Yasushi , Sedat John W. 
Published: June 2020

In an effort to understand the complex relationship between structure and biological function within the nucleus, we have embarked on a program to examine the three-dimensional structure and organization of Drosophila melanogaster embryonic chromosomes. Our overall goal is to determine how DNA and proteins are organized into complex and highly dynamic structures (chromosomes) and how these chromosomes are arranged in three dimensional space within the cell nucleus. Futher, we hope to be able to correlate structual data with such fundamental biological properties as stage in the mitotic cell cycle, developmental state and transcription at specific gene loci.Towards this end, we have been developing methodologies for the three-dimensional analysis of non-crystalline biological specimens using optical and electron microscopy. We feel that the combination of these two complementary techniques allows an unprecedented look at the structural organization of cellular components ranging in size from 100A to 100 microns.
A rotatable 3-D computer reconstruction of paper from light microscopic images of serial-sections
Authors: Neal R. J. , Telljohann M. 
Published: June 2020

The utilization of images from serial-sections to build 3-D models has always been a desirable goal of microscopists. This has been a formidable task because of the tedious effort required to obtain suitable microscopic images from properly registered serial-sections, and to build 3-D models from these images. With the advent of computerized imaging capabilities, 3-D modeling has been simplified considerably. It seemed likely, then, that by combining serial-sectioning techniques with computerized processing, a rotatable 3-D model of paper could be generated. Such a model could yield considerable insight into void structure and fiber relationships that relate to the strength and absorption qualities of paper. This data could lead to novel ways of manufacturing paper of improved quality.Small pieces of paper hand-sheets were embedded in plastic and polymerized at 60° overnight. Registration holes (50 μm Dia.) were burned into the block with an Ar laser.
Ultrastructural comparison of cynomolgus monkey liver samples following immersion fixation in different primary fixatives
Authors: Egy M. A. 
Published: June 2020

This study was undertaken to find an optimal primary fixative for the assessment of ultrastructural morphology of hepatic tissue from cynomolgus monkeys under common constraints in a pathology laboratory. No single fixative for electron microscopy is suitable for every organ, species or application. Immersion fixation is prescribed when a limited amount of tissue is available from biopsies or when tissues must be shared with other investigators. In addition, tissues are often collected at another location and then sent to the electron microscopist so a delay is incurred before processing is completed. The ultrastructural effects of eight fixatives and two designed delays were evaluated in this study.Fresh hepatic tissue was excised from the left lateral hepatic lobe of normal control young adult male cynomolgus monkeys and fixed by immersion according to 8 protocols.