bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Cross-Sectional Transmission Electron Microscopy to the Characterization of Ion-Implanted Semiconductors
Authors: Sands T.
Published: June 2020

Direct implantation of dopant ions is the most precise method for obtaining a desired dopant profile in a semiconductor substrate. However, in order to achieve satisfactory electrical properties, lattice defects introduced by the energetic dopant ions and by the subsequent annealing process must be confined or eliminated. Because of the many parameters which can be varied during implantation and annealing, it is not generally feasible to survey all conditions. Consequently, the most efficient approach is to understand the mechanisms of defect formation and annealing so that guidelines for choosing a set of implantation/annealing conditions can be determined.

Since implantation depths are usually much less than one micron, suitable defect characterization techniques must demonstrate high spatial resolution. Cross-sectional transmission electron microscopy (XTEM) is one such technique. With a resolution (lateral and depth) of ∼0.2nm, the atomic structure of implantation-related defects is accessible.
Electron Channeling Analysis and Z-C0ntrast Imaging of Dopants in Semiconductors
Authors: Pennycook S. J.
Published: June 2020

The determination of dopant distribution and lattice location are key elements in the characterization of ion-implanted, thermally processed semiconductors. We present here two analytical techniques for this purpose. The first is a channeling technique for the determination of substitutional fractions of dopants or impurities in any crystal structure, and the second is a means for imaging and elemental mapping of heavy elements in light materials, even if they are in solution.

Atom Location by Electron Channeling Analysis

It has only recently been realized that the orientation dependence of characteristic x-ray emission close to a Bragg reflection, long regarded as a hindrance to accurate microanalysis, can form the basis of a powerful lattice location technique. The first studies of this kind located trace elements in layer structure minerals, where it was known that the only possible sites for the impurity lay within the layer planes A and/or B. These restraints exclude many materials and here a generalization to any crystal structure is described.
Microstructural Aspects of Recrystallization-Controlled Rolling in V-Ti-N Steels
Authors: Burke M.G. , Fix R.M. , DeArdo A.J.
Published: June 2020

Recrystallization controlled rolling (RCR) has been developed as an economically viable alternative to conventional controlled rolling, a thermomechanica1 processing treatment currently employed in the steel industry. RCR processing involves deformation below the austenite grain coarsening temperature of the steel, followed by accelerated cooling to an intermediate temperature and air cooling to room temperature. The V-Ti-N system is well-suited to RCR processing because Ti (in the form of TiN precipitates) promotes a fine reheated austenite grain size while the V in solution in the austenite will be available for subsequent precipitation in the ferrite. The precipitation potential of V-Ti steels has been shown to increase with increasing N content and cooling rate.
Direct Observation of Defect Motion in Silicon By High-Resolution Transmission Electron Microscopy
Authors: Parker M. A. , Sinclair R.
Published: June 2020

Observations of defect motion by high resolution transmission electron microscopy (HRTEM) are rare. Unfortunately, the application of this technique has been limited to a few unique materials, those that can obtain sufficient thermal energy for the initiation of atomic motion through the heating effects of the incident electron beam. In earlier work, it was speculated that events such as the motion of crystal defects, observed in cadmium telluride (CdTe) with the electron beam heating method, might become evident in materials such as silicon (Si) if only sufficiently high temperatures could be achieved (∼ 600°C) in-situ.

A silicon specimen with a suitable population of defects was chosen for examination; it consisted of a cross-section of.3 μ ﹛100﹜ silicon on ﹛1102﹜ sapphire (SOS from Union Carbide) which was implant amorphized by 28Si+ ion implantation at an energy of ∼ 170keV.
Near-Surface Aggregation of Sn In Heavily Sn-Doped GaAs Films Grown By Molecular Beam Epitaxy
Authors: Chen S. H.
Published: June 2020

Sn has been used extensively as an n-type dopant in GaAs grown by molecular-beam epitaxy (MBE). The surface accumulation of Sn during the growth of Sn-doped GaAs has been observed by several investigators. It is still not clear whether the accumulation of Sn is a kinetically hindered process, as proposed first by Wood and Joyce, or surface segregation due to thermodynamic factors. The proposed donor-incorporation mechanisms were based on experimental results from such techniques as secondary ion mass spectrometry, Auger electron spectroscopy, and C-V measurements. In the present study, electron microscopy was used in combination with cross-section specimen preparation. The information on the morphology and microstructure of the surface accumulation can be obtained in a fine scale and may confirm several suggestions from indirect experimental evidence in the previous studies.
HREM Studies on a New Zeolite AlPO4 #5
Authors: Rai R. S. , O'Keefe M. A. , Thomas G.
Published: June 2020

Catalytic studies demonstrate that subtle structural differences among the family of zeolites have a marked effect on catalytic properties; therefore, exact knowledge of the zeolite framework structure is desirable. The useful role of HREM in structural studies of zeolites has already been established. AlPO4#5 is a newly synthesized aluminophosphate “molecular sieve” with zeolite-like properties having potential applications as adsorbents, catalysts and catalyst supports. It differs from aluminosilicates mainly due to the substitution of Si with P in the framework. Non-connecting parallel channels spanned by 12-rings in the as-synthesized material contains tetrapropyl- ammonium hydroxide species (fig. 1). Its ideal chemical composition is TPAOH.12AlPO4 and removal of the TPAOH by calcination at 400-600°C produces a molecular sieve for which absorption studies are consistent with unconnected pores bounded by 12-rings. The structural details of AlPO4#5 have been reported recently on the basis of x-ray diffraction. As it has not been studied so far by high resolution electron microscopy, we have used a JEOL 200CX in an attempt to examine local details of its framework at atomic level, detail that x-ray diffraction fails to reveal due to averaging effects.
Nickel Oxide Morphology In Nickel-Silica Catalysts
Authors: Dhere A. G. , Reucroft P. J. , De Angelis R. J. , Bentley J.
Published: June 2020

Supported metal catalysts of nickel on a suitable ceramic support are widely used in hydrogenation processes because of their high dispersion. However, large rafts of nickel in reduced Ni/Si02 catalyst have been observed. A study is being conducted to determine the origin of these structures in the catalyst preparation stage. An array of nickel oxide crystallites linked epitaxially with an interlayer of nickel silicate on the surface of the silica was initially postulated for the calcined catalyst. Quantitative x-ray diffraction analysis has shown that more nickel is bound in the form of nickel silicate than in nickel oxide, thereby confirming the coexistence of nickel oxide and nickel silicate. No previous direct observations of these structures have been reported.
SEM Characterization of Aged Coal Liquefaction Catalysts
Authors: Freeman G. B. , Heink J. B. , Davis B. H.
Published: June 2020

Coal liquefaction was identified as a national priority in the midseventies, Nonetheless, it was clear that oil is a limited resource and that the energy potential of this country's coal resources must be tapped in an efficient and environmentally sound manner. Coal liquefaction is essentially the thermal process of bond breaking and, if direct coal liquefaction is to succeed as a viable technology, yields must be improved by the use of selective catalysis.

While supported CoMo catalysts have been used routinely for hydrodesulfurization (HDS) in the petroleum industry, the environment of coal liquefaction is significantly more severe. Deactivation of the Mo or W and Ni or Co catalysts in coal liquefaction is quite rapid and is thought to be caused by a combination of coke formation (closing off catalyst pore structure), mineral deposition and catalyst sintering.
Some Contributions of Immunocytochemistry to Cell Biology
Authors: Novikoff Phyllis M. , Novikoff Alex B.
Published: June 2020

This presentation will highlight the application of immunocytochemistry in elucidating organelle function in biosynthetic and degradative intracellular pathways. Improved procedures in obtaining purification of proteins and production of antibodies with high degree of specificity in conjunction with advances in immunocytochemistry, have greatly expanded the number of proteins (and other antigens) that can be localized by in situ procedures. Immunocytochemical procedures have the advantages of: (a) providing direct visualization of intracellular antigens under conditions in which organelle structures and interrelations are maintained; (b) excluding cross-contamination of isolated subcellular fractions, particularly by as yet undefined cellular elements; and (c) demonstrating enzymes for which enzyme cyto-chemical methods are not available or reliable.
A Review on Colloidal Gold Post-Embedding Cytochemical Techniques
Authors: Bendayan Moïse
Published: June 2020

In 1971, colloidal gold was introduced in immunocytochemistry by Faulk and Taylor for the ultrastructural demonstration of antigenic sites at the surface of bacteria. Since then, application of this marker has been growing rapidly, extending its use to the various fields of cytochemistry. Indeed, it has been applied for pre- and post-embedding labeling of cell surface and intracellular binding sites respectively. It has been used in light microscopy as well as in both transmission and scanning electron microscopy, and thus appears today as the marker of choice in cytochemistry.

The present short review means to illustrate four different affinity techniques, which have been developed recently for the ultrastructural postembedding localization of various macromolecules using colloidal gold as the electron dense marker.
In Vitro Root Caries: Hexamethyldisilazane Treatment For SEM
Authors: Chan D.C.N. , Wefel J.S. , Dogan Umran
Published: June 2020

Characterization of in vivo and in vitro root caries systems have traditionally been carried out with transmitted light microscopy, polarized light microscopy and microradiography. Electron microscopy and probe analysis will provide additional information regarding the morphological and chemical features of sound and carious dentin-cemental surfaces. Of equal importance is the correlation of E.M. observations to that ovtained by light microscopy and microradiographic techniques.

Previous E.M. investigations of early carious cementum showed a characteristic cross-striations of collagen fibers in sound cemental matrix. These striations were observed to be partially or completely lost in cemental lesions. Another study suggested that the breakdown of the major portion of the collagen occurred late or was the final step in the destructive phase of the carious process.
Simultaneous Comparison of Two Techniques For X-Ray Microanalysis of Tissue Sections
Authors: Saubermann A.J. , Scheid V.L. , Dobyan D.C. , Bulger R.E.
Published: June 2020

Major differences in elemental and water content in cells of rat renal papillae in antidiuresis have been reported using x-ray microanalysis by us and by Beck et al. Various reasons for these reported differences have been suggested, including the analytical algorithm used, cryosectioning at “warmer” temperatures leading to elemental displacement, and biological differences. The purpose of these studies is to determine the reasons for these reported differences by comparing both our methods for x-ray analysis of frozen hydrated tissue sections and the method of Beck et al. simultaneously on the same tissue. Our methodology uses fully hydrated tissue sections without external standards, while Beck et al. uses frozen dried cryosections with an albumin external standard (Ringer's solution in 20% albumin). In these studies two anatomical areas of the rat kidney were subjected to analysis using both our methods and theirs simultaneously: 1) the proximal tubule cell (PTC) from rat renal cortex, and 2) the antidiuretic papilla prepared according to Beck et al.
Effects of Cytochalasin B on Naegleria Fowleri Amoebostomes
Authors: Cole T. B. , John D. T.
Published: June 2020

Naegleria fowleri is an opportunistic free-living amoeboflagellate that is the causative agent of the rapidly fatal disease in man called primary amoebic meningoencephalitis. This pathogenic amoeba displays surface sucker-like structures called amoebostomes that have been shown to play an active role in a unique form of engulfment. Transmission electron microscopic studies of amoebostome profiles demonstrate associated cytoskeletal components. It is known that cytochalasin B (CCB) produces reversible alterations in the cell's cytoskeleton and in turn modification of surface characteristics. Therefore, the purpose of this study is to observe the morphological effects that CCB has on amoebostome morphology.
Conformation of Free Ribosomal RNAs by STEM and Wet Film Technique as a Phylogenetic Probe
Authors: Oostergetel G.T. , Wall J.S. , Hainfeld J.F. , Boublik M.
Published: June 2020

The similarity of ribosomes involvement in protein synthesis in evolutionarily distant species makes this cellular organelle an attractive phylogenetic probe. The evolutionary changes in ribosomes are reflected not only in the morphology of the ribosome but also in the composition and structure of its components - proteins and RNAs.

We have investigated the extent of structural similarity of free rRNAs from baby hamster kidney (BHK) cells and Escherichia coli as examples of RNAs from a eukaryote and a prokaryote, respectively. Using dedicated STEM and “wet film” technique (Wall et al. these Proceedings) for specimen deposition we have improved considerably the resolution of RNA conformation in comparison to the glow discharge technique. A gallery of individual unstained freeze-dried 28S RNA molecules Isolated from the large (60S) ribosomal subunits from BHK cells, obtained by deposition from distilled water, is presented in Fig. 1a.
Endoplasmic Reticulum Specializations in Aging Hamster Neurons
Authors: Tank Buschmann MB.
Published: June 2020

Rough endoplasmic reticulum has been observed in specialized forms, including the lamellar body (LB) the subsurface cistern (SSC) and a combination of the two known as the lamellar body/sursurface cistern (LB/SSC, Fig. 1) complex. These structures have been described in the neurons of various developing and adult mammals. However, there are no published quantitative reports of these endoplasmic reticulum specializations (ERS) over the life span of a species. In this investigation, quantitative changes were studied in 15- (immature), 100-, 500-(mature), 600- and 700-day (aged) postnatal pyramidal neurons in the frontal cortex of golden hamsters (Mescricetus auratus).

The anesthetized animals were perfused with glutaraldehyde-paraformaldhyde in sodium cacodylate buffer (pH 7.3) after the method of Peters. Tissue samples were post-fixed in 2% osmium tetroxide, dehydrated in acetone and embedded in Epon-Araldite resin. Lengths were obtained with the BioQuant Image Analyzer (R & M Biometrics, Nashville, TN).
Tobacco Mosaic Virus-Infected Tissue
Authors: Henry Egbert W.
Published: June 2020

Tobacco mosaic virus (TMV) infection has been studied in several investigations of Nicotiana tabacum leaf tissue. Earlier studies have suggested that TMV infection does not have precise infective selectivity vs. specific types of tissues. Also, such tissue conditions as vein banding, vein clearing, liquification and suberization may result from causes other than direct TMV infection. At the present time, it is thought that the plasmodesmata, ectodesmata and perhaps the plasmodesmata of the basal septum may represent the actual or more precise sites of TMV infection.

TMV infection has been implicated in elevated levels of oxidative metabolism; also, TMV infection may have a major role in host resistance vs. concentration levels of phenolic-type enzymes. Therefore, enzymes such as polyphenol oxidase, peroxidase and phenylalamine ammonia-lyase may show an increase in activity in response to TMV infection. It has been reported that TMV infection may cause a decrease in o-dihydric phenols (chlorogenic acid) in some tissues.
Scanning Electron Microscopy of Staphylococcus Epidermidis Adherence to Continuous Ambulatory Peritoneal Dialysis Catheters
Authors: Lamoreaux William J. , Smalley David L. , Baddour Larry M. , Kraus Alfred P.
Published: June 2020

Infections associated with the use of intravascular devices have been documented and have been reported to be related to duration of catheter usage. Recently, Eaton et al. reported that Staphylococcus epidermidis may attach to silastic catheters used in continuous ambulatory peritoneal dialysis (CAPD) treatment. The following study presents findings using scanning electron microscopy (SEM) of S. epidermidis adherence to silastic catheters in an in vitro model. In addition, sections of polyvinyl chloride (PVC) dialysis bags were also evaluated by SEM.

The S. epidermidis strain RP62A which had been obtained in a previous outbreak of coagulase-negative staphylococcal sepsis at local hospitals was used in these experiments. The strain produced surface slime on exposure to glucose, whereas a nonadherent variant RP62A-NA, which was also used in these studies, failed to produce slime. Strains were grown overnight on blood agar plates at 37°C, harvested from the surface and resuspended in sterile saline (0.85%), centrifuged (3,000 rpm for 10 minutes) and then washed twice in 0.1 M phosphate-buffered saline at pH 7.0. Organisms were resuspended at a concentration of ca. 106 CFU/ml in: a) sterile unused dianeal at 4.25% dextrose, b) sterile unused dianeal at 1.5% dextrose, c) sterile used dialysate previously containing 4.25% dextrose taken from a CAPD patient, and d) sterile used dialysate previously containing 1.5% dextrose taken from a CAPD patient.
Ultrastructure of Equine Mast Cells in Bronchoalveolar Lavage and Lung
Authors: Yamashiro S. , Bast T. , Viel L. , Harris W.
Published: June 2020

Examination of the cells in the bronchoalveolar lavage is frequently used for the evaluation of inflammatory lesions of the lower airways and alveoli. Identification of the cells in the lavage is important for differential counts. It has been shown that human mast cells and basophils exhibited similar morphological and histochemical features at light microscopic level and they were collectively called basophiloid cells. Dvorak et al have reviewed the ultrastructural characteristics of these cells in humans, guinea pigs and mice but no such study has been done on horses.

Bronchoalveolar washings collected from three adult geldings were centrifuged in Wintrobe tubes, followed by the fixation in 2.5% glutaraldehyde in 1.0 M phosphate buffer at pH 7.2. The samples were post-fixed in 2.0% osmium tetroxide in the phosphate buffer and embedded in Epon 812. Small pieces of lung tissues from three adult, normal horses were also processed for transmission electron microscopy (TEM). In addition, blood samples from two adult horses were processed for TEM.
Hepatic Ultrastructure and Biochemistry Following Insulin Withdrawal
Authors: Garfield S.A. , Fellows M.F. , Cardell R.R.
Published: June 2020

This study examines the hepatic ultrastructural and biochemical responses following insulin withdrawal from insulin-maintained streptozotocin- diabetic rats. This hormonal manipulation permitted analysis of the hepatocellular events occurring during diabetic onset. Normoglycemia was maintained in the induced diabetic rats for seven days with daily injections of 5 U intermediate acting insulin (NPH-Iletin) per 100 gram body weight. This was followed by treatment for 24 hr with regular short acting insulin at 6 hr intervals (2.5 U/100 gr b.w.).

Animals were sacrificed at intervals following the last insulin injection. Plasma was collected for glucose and insulin determinations. Liver samples were prepared for ultrastructural analysis or were collected for Isolation of rough and smooth endoplasmic reticulum fractions (RER, SER). Isolated RER and SER membrane preparations were analyzed for glucose-6-phosphatase (G-6-Pase) activity, as well as for phospholipid, cholesterol, and fatty acid composition.
Ultrastructure of Major Conducting Airway Epithelium in the Guinea Pig
Authors: Davis M. L. , Ford J. O. , Dodson R. F.
Published: June 2020

Guinea pigs have served as experimental models in a variety of pulmonary research including that concerned with asbestos related disease which is of particular interest in our laboratory. A search of the literature revealed several papers concerned with various characteristics of airway epithelium in both normal and experimentally manipulated guinea pigs, yet no studies could be found which systematically addressed the epithelial structure and organization in major airways. The present study was undertaken to fully characterize these areas at the electron microscopic level in order to provide data from healthy animals which can act as baseline information in experimental studies of airway epithelium. Initial findings from the trachea and main bronchi are presented here.
Preliminary Localization of a Cell Type-Specific Antigen in the Accessory Glands of the Male Mealworm Beetle by Immunoelectron Microscopy
Authors: Bricker C.S. , Grimnes K.A. , Happ G.M.
Published: June 2020

The reproductive accessory gland complex of male Tenebrio molitor consists of two sets of paired glands: the bean-shaped (BAGs) and the tubular-shaped accessory glands (TAGs). Unlike the TAG, which contains a single cell type, the BAG contains at least seven cell types differentiated by the ultrastructure of their secretory granules. The BAG also synthesizes a wider variety of proteins. As the gland becomes mature, granules are secreted into the lumen of the BAG, forming the plug, and are molded into the spermatophore, a complex structure used to transmit sperm to the female during mating. Up to this point it has been difficult to correlate individual protein species with specific granule types. Therefore, we have turned to monoclonal antibody technology and immunoelectron microscopy to investigate the production, localization and fate of BAG and spermatophore proteins.
Identification of Maize Rayado Fino Virus by Immunoelectron Microscopy
Authors: Bradfute O. E.
Published: June 2020

Maize rayado fino virus (MRFV) causes a severe disease of corn (Zea mays) in many locations throughout the neotropics and as far north as southern U.S. MRFV particles detected by direct electron microscopy of negatively stained sap from infected leaves are not necessarily distinguishable from many other small isometric viruses infecting plants (Fig. 1).

Immunosorbent trapping of virus particles on antibody-coated grids and the antibody coating or decoration of trapped virus particles, was used to confirm the identification of MRFV. Antiserum to MRFV was supplied by R. Gamez (Centro de Investigacion en Biologia Celular y Molecular, Universidad de Costa Rica, Ciudad Universitaria, Costa Rica).

Virus particles, appearing as a continuous lawn, were trapped on grids coated with MRFV antiserum (Fig. 2-4). In contrast, virus particles were infrequently found on grids not exposed to antiserum or grids coated with normal rabbit serum (similar to Fig. 1). In Fig. 3, the appearance of the virus particles (isometric morphology, 30 nm diameter, stain penetration of some particles, and morphological subunits in other particles) is characteristic of negatively stained MRFV particles. Decoration or coating of these particles with MRFV antiserum confirms their identification as MRFV (Fig. 4).
The Effects of Estradiol on Chronically Damaged Human Fallopian Tubes: A SEM Study
Authors: Toledo A. , Stoelk G. , Yussman M. , Apkarian R.P.
Published: June 2020

Today it is estimated that one of every three women in the U.S. will have problems achieving pregnancy. 20-30% of these women will have some form of oviductal problems as the etiology of their infertility. Chronically damaged oviducts present problems with loss of both ciliary and microvillar epithelial cell surfaces. Estradiol is known to influence cyclic patterns in secretory cell microvilli and tubal ciliogenesis, The purpose of this study was to assess whether estrogen therapy could stimulate ciliogenesis in chronically damaged human fallopian tubes.

Tissues from large hydrosalpinges were obtained from six women undergoing tuboplastic repair while in the early proliferative phase of fheir menstrual cycle. In each case the damaged tissue was rinsed in heparinized Ringers-lactate and quartered.
Ultrastructural Characteristics of Vaginal Epithelium of Persistent Estrous Rats
Authors: Francis K. Khosho , Robert C. Kaufmann , Kofi S. Amankwah
Published: June 2020

Adult female rats exposed to constant light will develop anovulatory acyclicity characterized by persistent vaginal cornification (PE) and formation of multiple large cystic follicles on the ovaries. The purpose of the present communication is to describe the ultrastructural changes in vaginal epithelia in PE rats as compared to that in normal estrous rats.

Persistent vaginal estrous with PCO was induced in a group of Sprague-Dawely rats by exposure to constant light for 50-150 days. Rats in normal estrous, as determined by vaginal smears, were used as controls. Nembutal- anethesized rats were perfused through the aorta with 2.5% gluteraldehyde in 1M sodium cacodylate buffer (pH 7.3). The mucosa of the vaginal folds just inferior to the cervix were dissected by microsurgery, postfixed, stained with 0.5% ruthenium red in 1% osmium tetroxide, dehydrated, and embedded in polybed. Thick sections (1μ) were stained with toludine blue for light microscopy studies. Thin sections were stained with uranyl acetate and lead citrate.
Ultrastructure of the Spermatophore of a Mealworm Beetle
Authors: Bricker C.S. , Happ G.M.
Published: June 2020

The male mealworm beetle, Tenebrio molitor, transfers sperm to the female by means of a spermatophore, or sperm sac. This study was undertaken to determine the ultrastructure of the spermatophore and the origins of its components.

For ultrastructural studies spermatophores were fixed in 3% glutaraldehyde in 0.1 M phosphate buffer, pH 7.2, post-fixed in OsO4,, dehydrated in ethanol and embedded in Spurrs resin. Silver sections were cut on a Reichert Om U2 microtome, stained with uranyl acetate and lead citrate, and examined in a Philips 201 microscope at 60kV.

The spermatophore is an elongate sac composed of an inner cylinder within an outer wall. A lumen is located between the outer wall and cylinder, and contains sperm and secretory products from the TAGs (a pair of tubularshaped reproductive accessory glands). The outer wall consists of 4 or 5 concentric layers formed by the secretory products from the paired beanshaped accessory glands (BAGs). The cylinder contains the same layers as the outer wall, but in a reversed order of location, plus a central core which is a mixture of different products and possibly cell debris (Fig. 1).
A Comparison Between Sterological Point Counting and Digitizing Tablets
Authors: Basgen John M. , Ellis Eileen N. , Michael Mauer S. , Steffes Michael W.
Published: June 2020

To determine the efficiency of methods of quantitation of the volume density of components within kidney biopsies, techniques involving a semi-automatic digitizing tablet and stereological point counting were compared.

Volume density (Vv) is a parameter reflecting the volume of a component to the volume that contains the component, e.g., the fraction of cell volume that is made up of mitochondrial volume. The units of Vv are μm3 /μm3.

Kidney biopsies from 15 patients were used. Five were donor biopsies performed at the time of kidney transplantation (patients 1-5, TABLE 1) and were considered normal kidney tissue. The remaining biopsies were obtained from diabetic patients with a spectrum of diabetic kidney lesions. The biopsy specimens were fixed and embedded according to routine electron microscogy protocols. Three glomeruli from each patient were selected randomly for electron microscopy. An average of 12 unbiased and systematic micrographs were obtained from each glomerulus and printed at a final magnification of x18,000.
Ultrastructure of Arterial Lesions in Rats Infused With Fenoldopam Mesylate, A Dopaminergic Agonist
Authors: Sowinski J. M. , Bugelski P. , Walsh Vockley C. , Arena E. , Morgan D. G.
Published: June 2020

Fenoldopam mesylate, a dopaminergic vasodilator, has been found to induce lesions in renal and splanchnic arteries of rats upon administration by continuous intravenous (i.v.) infusion. Further studies were undertaken by scanning and transmission electron microscopy (SEM and TEM, respectively) to investigate the ultrastructure and pathogenesis of this arterial lesion. For SEM, groups of Sprague-Dawley, CD® rats, each of 3 males, were administered 50 μg/kg/min of fenoldopam by i.v. infusion for 24 hours. Control rats were similarly infused with 0.9% saline alone. After infusion, tissues were fixed by perfusion under constant pressure (110 ± 5 mm Hg) for 20 minutes with 1% glutaraldehyde in 0.1 M phosphate buffer at 37°C. A 0.05% solution of toluidine blue was introduced immediately after the fixative in order to stain arteries of interest, and thus aid in their visualization.
Persistence of Synaptic Vesicles After Photodynamic Abolition of Quantal Release at the Neuromuscular Junction of the Lizard
Authors: Pappas G. D. , Politoff A. L. , Lifschitz W. , Kriho V.
Published: June 2020

We have used rose bengal (RB) to study the ultrastructural and physiological effects of in vivo photooxidation of the presynaptic terminal of the neuromuscular junction. Rose bengal (RB) is a powerful xanthine photosensitizer capable of inducing fairly selective photooxidation of histidinyl residues of proteins when exposed to light in the present of O2 (from air) and pH near 7.0. Recent observations by Politoff and Lifschitz show that RB is taken up spontaneously by the nerve terminal and selectively accumulated in the presynaptic region; after uptake of RB, illumination of the presynaptic region with a microscopic photic stimulus (1.3 x 103 erg) causes a brief (15 min) and small burst (3.0 x 103 total release) of miniature end plate potentials (m.e.p.p.), followed by total abolition of m.e.p.p.'s, in spite of preservation of postsynaptic sensitivity.
Lamellar microstructure of discontinuous precipitation reaction front in Cu-7.5%In
Authors: Solorzano I. G. , Audier M.
Published: June 2020

There is an increasing body of evidence for discontinuous precipitation (DP) as a general solid state phase transformation in materials. The understanding of the DP phenomenon, however, requires to establish its energy balance. The lamellar microstructure at the grain boundary reaction front (RF) is of particular interest since it results from the optimization of, at least, chemical, capillary and interfacial energy terms coupled with the boundary mobility at a given undercooling. Our investigation into this field has lead us to the conclusion that an additional term reflecting the residual stresses in the transformed product should be incorporated. In the present paper, microstructural features focused at the lamellar growth front are illustrated and discussed supporting the idea that DP is a non-equilibrium reaction.

The alloy used for this study, Cu-7.5at.%In, was prepared at the Max-Planck-Institut, Stuttgart, from high purity components by induction melting under argon atmosphere and chill cast. After homogenization at 600°C/300h samples were directly aged isothermally at different temperatures and quenched. The parent FCC matrix α decomposes into depleted α lamellae and tetragonal Cu3In β lamellar precipitates.
Observations on the growth of barium bismuth oxide thin films
Authors: Norton M G. , Hellman E.S. , Hartford E.H. , Carter C.B.
Published: June 2020

The bismuthates (for example, Ba1-xKxBiO3) represent a class of high transition temperature superconductors. The lack of anisotropy and the long coherence length of the bismuthates makes them technologically interesting for superconductor device applications. To obtain (100) oriented Ba1-xKxBiO3 films on (100) oriented MgO, a two-stage deposition process is utilized. In the first stage the films are nucleated at higher substrate temperatures, without the potassium. This process appears to facilitate the formation of the perovskite (100) orientation on (100) MgO. This nucleation layer is typically between 10 and 50 nm thick. In the second stage, the substrate temperature is reduced and the Ba1-xKxBiO3 is grown. Continued growth of (100) oriented material is possible at the lower substrate temperature.
Current and future prospects in instrumentation of HREM
Authors: Herrmann K.-H.
Published: June 2020

In material research the goal of the electron optical system is the optimum recovery of the object information carried by the beam aiming at the retrieval of both structural and chemical information down to atomic dimensions. Instrumentation has reached a high level of maturity in approaching physical limits set by both electron wavelength and aberrations of axially symmetrical lenses in CTEM and STEM. Present trends are seen in further perfections of the optical components to attain an interpretable transfer limit above 10 nm-1, in increasing the spatial resolution and overcoming the present limits of detection in microanalysis, in the uncompromising combination of several techniques in one instrument (e.g.HREM, CBED, STEM and EELS), in the progressing use of computers for EM control, conversion and storage of data, in online processing for immediate interpretation of images and feed-back to the EM as well as in some rather “non-conventional” ways for restoring the object wave function under elimination of aberrations, for which holography may be a particularly promising example.
New detection system for HAADE and holography in STEM
Authors: Mankos Marian , Wang Shi Yao , Weiss J.K. , Cowley J.M.
Published: June 2020

A novel detection system has been designed and realized experimentally on the HB5 STEM instrument. Shadow images, diffraction patterns as well as high-angle annular dark field and bright field images are observed simultaneously with high efficiency using CCD and TV cameras. The microscope can be operated in a wide range of instrument modes which includes the implementation of new techniques for high resolution imaging.

As shown in Fig. 1, the detection system has three triple choice stages. Diffracted beams can be collected by three P47 fast phosphor annular detectors inclined at 45 degree to the axis and having different inner and outer acceptance angles, which can be adjusted by the postspecimen lenses. The detector is observed through a window by a photomultiplier. The annular detectors have been used also for a new bright field STEM technique which utilizes the inner rim of the detectors to collect only the outermost annular part of the central beam and promises an improvement in resolution by a factor of about 1.6. Initial results show some promise (Fig. 2). The transmitted beam is then converted into a light signal in YAG and P47 detectors; optionally the central part of the beam can be detected in the EELS spectrometer. The generated light signal is reflected through a system of mirrors, exits the vacuum chamber and is collected with high efficiency by high aperture optical lenses.
Observations of coexistence of FCC and HCP phases in C60by HREM
Authors: Li Z.G. , Fagan Paul J.
Published: June 2020

Since the discovery of a large scale synthesis of fullerenes there has been intense interest in the structure of these materials. The first diffraction data suggested that crystalline C60had a hexagonal close-packed (hep) structure with a nearest neighbor distance of 10.04 Å. The possibility of a disordered stacking of C60molecules was first noted in this study. Since then, there has been some confusion regarding the exact crystalline structure of C60as determined by electron and X-ray diffraction. In particular, a diffraction feature corresponding to a spacing of 8.7 Å has been noted in several studies. Recendy there had been a growing consensus that fcc is the correct structure for sublimed C60. Although the internal carbon atom arrangement of the C60molecules cannot be determined, the actual packing and defects in C60crystals over small and relatively large regions are readily seen by HRTEM. We have found by direct imaging a relatively large region of defect-free hep packing of C60spheres sublimed onto a relatively cool microscopy grid.
Test of a method for phase retrieval in HREM
Authors: Beeching M.J. , Spargo A.E.C.
Published: June 2020

1. Introduction

Several methods of phase retrieval from HRTEM image intensity distributions have been proposed but no standard method has emerged. We report on the results achieved using a technique based on a development of the “focus variation method”. The dependence of the retrieved wavefunction on various experimental parameters is investigated and the method tested using computer simulated images. The method is shown to be useful in finding the complex wavefield at the exit surface of the specimen, but the relationship of this to the specimen structure is left as a seperate problem.
Measurement of PCTF parameters with high accuracy
Authors: de Jong A.F. , Coene W.M.J. , Koster A.J.
Published: June 2020

Measurement of electron-optical parameters in TEM is important for two reasons: a) for automatic correction of focus, astigmatism and beam-tilt misalignment (autotuning) and b) for the accurate determination of the phase-contrast transfer function (PCTF) which is needed for a correct interpretation of high-resolution electron microscopy (HREM) images. This paper addresses specifically methods adapted to reach the second goal, stressing accuracy rather than speed and robusteness.
Shadow images for in-line holography in STEM
Authors: Wang Shi-Yao , Weiss J. K. , Cowley J. M.
Published: June 2020

Shadow images are obtained on the detector plane when the specimen in a STEM instrument is illuminated by a stationary beam formed with a very large or no objective aperture. It has been recognized for some time that the shadow image formed after a thin crystal specimen in the diffraction plane of a STEM instrument with a field emission gun can be treated as an in-line hologram. Since the transmitted and diffracted beams are added to give interference effects, all the information on the relative phase of the scattered beams is recorded in the shadow image. In fact, this is basically equivalent to the original scheme envisioned by Gabor, where he proposed that a reconstruction could be made from a hologram so that the imperfection due to spherical aberration of the objective lens could be corrected and improved resolution could be achieved.
The role of microscopy in the alloy design of Ni- and Fe-based aluminides
Authors: Horton J.A.
Published: June 2020

During the last 10 years, there has been a resurgence of interest in ordered alloys for structural uses due to the discovery of the dramatic ductilizing effect of boron on grain boundaries in Ni3Al. With this discovery, it was hoped that the property of an increase in strength as the temperature is increased could be utilized as well as the excellent oxidation resistance. Now, alloys based on Ni3Al are in use in specialized industrial applications, such as high temperature forging dies and being tested for use as turbocharger rotors. Due to the successful control of the grain boundary strength in Ni3Al, other systems were reexamined. For example, Fe3Al was also thought to have inherently brittle grain boundaries, however it was found that with purer alloys the material failed by cleavage. Subsequently, development of practical, inexpensive, oxidation resistant alloys has proceeded. Fe3Al alloys are currently being tested for automobile exhaust applications.
Aluminum-lithium alloys: A solution looking for a problem?
Authors: Williams D.B.
Published: June 2020

For over a decade, Al-Li base alloys have been described as “the next generation of aerospace alloys”, although to date not much metal is actually flying. The addition of up to 3 wt. % (11 at.%) Li to Al results in decreased density (for obvious reasons) and increased modulus (for unknown reasons). This combination of decreased density and increased stiffness translates into millions of dollars saved in aircraft operation (whether military or civilian) and as a result the aerospace and aluminum industries have invested tens of millions of dollars in an attempt to produce commercial Al-Li based alloys. Electron microscopy and microanalysis have played a major role in the understanding of the physical metallurgy of these alloys, which have yet to see significant service. Their future is uncertain, although there is some limited use for alloys of Al-Li-Cu-Mg-Zr.
Role of analytical transmission EM in the study of Zr Pressure-tube alloys
Authors: Weatherly G.G. , Perovic A. , Perovic V. , Purdy G.R.
Published: June 2020

Zirconium alloys are widely used in the Candu nuclear power generating system because of their unique combination of creep and corrosion resistance properties coupled with a low neutron cross section. The Zr-2.5 wt%Nb alloy has been extensively studied because it is the key component in pressure tubes. Pressure tubes are fabricated by extrusion in the two phase (α + β) field in the binary phase diagram, followed by cold work and stress relief heat treatments. As a result of this treatment, the alloy has a complex microstructure consisting of a duplex α + βzr or α + βNb structure (depending on the particular heat treatment), superimposed on which is a dislocation structure associated with the working operation. Typical microstructures are shown in Figs.l and 2. If the alloy is quenched from the β phase field (1000° C), a Widmanstätten α-βzr microstructure is produced (Fig.la). In the extruded state (Fig.lb), the βZr phase is now elongated and linked by a substructure which contains both  and  dislocations. Cold working followed a stress relief heat treatment at 400°C for 24 hrs introduces predominantly  dislocations, while the βZr phase (which is metastable) has decomposed to form discrete arrays of βNb (Fig-lc). Examples of the dislocation substructure are shown in Fig.2. Boundaries containing both  and  dislocations are observed. The misorientation at the boundaries is typically a few degrees. They are often stepped or faceted. In Fig.2 the steps correspond to a  dislocation which has dissociated to form two /2 dislocations.
Interfaces in high-temperature superconductors
Authors: Merkle K.L. , Gao Y.
Published: June 2020

After the discovery of high-temperature superconductors (HTS) five years ago, it soon became apparent that their interfacial characteristics would play an extremely important role in any foreseeable applications of these materials. In recent commercial devices, the weak-link characteristics of grain boundaries (GBs) have in fact been exploited to manufacture Josephson junction SQUIDS. On the other hand, the low critical current density of HTS is a considerable limitation for practical applications of the zero-resistance property, particularly in bulk materials. The weak-link behavior of GBs is largely responsible for this, but other types of interfaces such as those formed by metallic contacts or the interfaces between the substrate and a HTS thin film are also critical to the application of these materials. We shall review here some of the important interface issues that have been addressed by TEM techniques, but shall focus largely on the connection between the critical current (Jc) that can be transported across a grain boundary and its atomic-scale structure and composition.
Analysis of moiré patterns in images of thin YBa2Cu3O7-δ films on MgO
Authors: Norton M. Grant , Carter C. Barry
Published: June 2020

Moiré fringes arise from the interference between diffracted beams from two overlapping crystals (double diffraction) and in the bright-field case the forward scattered beam. The fringe patterns act as magnifiers of lattice imperfections and small deviations from perfect crystallographic orientation and symmetry. Moiré patterns have been used previously to study, for example, the growth of metal films on substrates such as molybdenum disulfide—which can easily be prepared to electron transparency. Moiré patterns can be used to identify microstructural defects in epitactic deposits. For example, the presence of rotationally misaligned grains, the presence of dislocations, and residual interfacial strain will be revealed in the fringe pattern.
Low-dose high-resolution EM of zeolite materials with slow A scan CCD camera
Authors: Pan M. , Crozier P.A.
Published: June 2020

Zeolite materials are widely used as an important type of catalyst in oil industry. Their catalytic properties and performance are closely related to their unique structures. Use of high resolution electron microscopy (HREM) to characterize structures of zeolite materials has been limited mainly due to the great sensitivity of the framework structures to electron beam irradiation used in the observation. With the recent development in solid state electronics, a new type of image recording device, known as a charge-coupled-device (CCD), has been made possible. Among many of its superior properties, it has been found that the very low noise level present in a slow scan CCD camera offers the possibility of recording high resolution structure images of zeolite materials with very low electron beam dose. The digital storage of CCD images allows on-line image processing to be performed at the microscope, thus making the recording of low dose electron microscope images more efficient. Image processing was also found to be essential in extracting high resolution structure information contained in the noisy low dose HREM CCD images.
Fractal geometry of carbonaceous aerosol particles as determined using Transmission Electron Microscopy
Authors: Katrinak Karen A. , Rez Peter , Perkes Paul R. , Buseck Peter R.
Published: June 2020

Carbonaceous aggregates collected from the aerosol of Phoenix, Arizona have an irregular branched morphology. The aggregates resemble combustion soots and were probably emitted by motor vehicles. Fractal analysis provides a means of quantifying morphologic variations among aggregates and relating these variations to mechanisms of formation. Bright-field transmission electron microscope (TEM) images of 38 individual aggregates were recorded on negatives at magnifications of 15,000 to 200,000. The aggregates have maximum lengths ranging from 0.21 to 2.61 μm and are composed of interconnected spherules, each averaging 26 nm in diameter. The number of spherules in each aggregate ranges from 32 to 1842; the average number is 551. “The nesting squares” method of fractal analysis was applied to digital binary images to calculate the fractal dimension (D) of each aggregate.