bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of accelerating voltage on electron diffraction structure analysis of organic crystals: Copper perchlorophthalocyanine
Authors: Dorset D. L. , Tivol W. F. , Turner J. N.
Published: June 2020

It is well known that the perturbation of measured electron diffraction intensities from thin microcrystals by multiple beam dynamical scattering is a function of crystal thickness, atomic number of the crystal components and the electron wavelength. For organic crystals, an attempt was made to calculate optimal conditions for collecting intensity data in order to permit ab intio crystal structure analyses to be carried out. Although the maximum crystal thickness giving quasi-kinematical diffraction intensities was found to increase with electron accelerating voltage, as expected, an optimal wavelength was also determined, beyond which the flattening of the Ewald sphere was expected to bring more high angle reflections into the convolution terms of the multi-slice expression. However, this latter aspect may actually be incorrectly represented by the computational model, because the significant thermal motion found for many organic crystals was not considered. For this reason, an experimental evaluation of the problem is being made using thin epitaxial crystals of copper perchlorophthalocyanine.
Polish-induced damage in GaAs: A systematic TEM investigation
Authors: Yegnasubramanian S. , Carver G. E.
Published: June 2020

Gallium Arsenide Integrated Circuit (IC) Technology demands extremely flat and almost “damage-free” GaAs wafers to maximize the yield in the manufacturing of ICs. These devices are fabricated on oriented surfaces of the crystals, which have been polished to a high degree of Harness and smoothness. The polishing procedures typically involve the use of abrasives successively to result in finer surfaces with a final chemical polishing step to remove the surface damage caused by the abrasives. However, if the final polishing step does not result in damage-free surfaces, local variations in the crystallographic orientation of the surface may lead to defective device structures. Extensive reviews are available in literature on the aspects of etching of GaAs substrates, including procedures for the preparation of polished substrates and on the revelation of defects by selective etchants.
Strain field measurement of plate-like defect in silicon
Authors: Chen Y. L. , Carpenter R. W.
Published: June 2020

Strain contrast around the precipitate in crystalline solid has been interpreted as due to the elastic distortion of the matrix around the precipitate. Adding the displacements into the dynamical equations of diffraction contrast in the 2-beam form developed by Howie and Whelan, and using the column approximation to calculate the intensities point by point, it is possible to obtain the intensity map of the strain contrast for a particular strain parameter ε. Ashby and Brown showed that the strain-measuring methods for the simplest case of spherical precipitate can be extended to determine the strain of the plate-like defect (PLD) normal to the plane of the plate. Most of the precipitates in silicon induce strain fields in the surrounding matrix with PLD the largest. In this abstract, we are trying to measure the strain field ε of PLD in silicon by matching the experimental and simulated images.
Microstructure of silicon implanted with MeV gold ions
Authors: Kim M.J. , Catalano M. , Sjoreen T.P. , Carpenter R.W.
Published: June 2020

High-energy implantation of silicon is of great interest in recent years for microelectronics due to the formation of a buried damage or dopant layer away from the active region of the device. The damage nucleation and growth behavior is known to vary significantly along the ion's track for MeV irradiation. In this paper, a detailed characterization of the damage morphology produced by MeV gold ions for different doses into single crystal Si, as well as the associated annealing behavior, is presented.

Single crystal n-type Czochralski silicon {001} wafers were implanted with Au++ ions from doses of 1x1015 to 3x1016 cm-2 at 2-3 MeV. Specimen temperatures for all implantations were 20 or 300°C. A measurement with an infrared pyrometer of the implanted surface indicated a slight temperature rise during ion irradiation. The compositional and damage profiles were determined by Rutherford backscattering/channeling spectroscopy (RBS). Cross-sectional TEM samples for microstructural characterization were prepared by mechanical polishing and ion milling. A Philips 400ST/FEG analytical microscope was used for nanoprobe experiments, at 100 kV. Microstructural investigation was performed using ISI-002B and JEM-2000FX microscopes, at 200 kV.
Microstructural characterization of oxygen-implanted poly-Si layers
Authors: David Theodore N. , Huang WenLing M.
Published: June 2020

Poly-Si layers were evaluated that had been exposed to varying doses of oxygen-implant prior to an anneal. The layers were doped (by implantation) with arsenic. Oxygen implantation was found to modify the conductivity of the doped poly-Si films. The microstructural behavior of the films was of interest (as potentially enabling explanation of the modified conductivity).

The oxygen implant doses investigated in this study were 1E14 and 1E16 cm-2. The arsenic dose used (dopant incorporated by implantation) was 1.3E13 cm-2. The oxygen-implantedpoly-Si layers were annealed (rapid-thermal anneal, “RTA“) at 1050°C for 30 seconds. Cross-section TEM specimens were prepared in the 110 substrate-geometry, and plan-view TEM specimens in the 100 substrate-geometry. These were then analyzed using selected-area diffraction, bright-field, and dark-field images under gradually varying conditions of electron-beam tilt. A JEOL JEM 200CX transmission electron microscope was used for analysis, operating at 200 kV.
Damage Evolution in Silicon Nitride under Repeated Dynamic Loading
Authors: Sharma Vinod , Vecchio Kenneth S. , Nemat-Nasser S.
Published: June 2020

The high modulus and limited plasticity of most ceramic materials inhibits the systematic study of deformation and fracture mechanisms. However, the use of repeatedly applied transient stress pulses allows incremental damage to be introduced without necessarily fracturing the specimen. In this study two types of hot pressed silicon nitrides, one having an amorphous boundary phase (6% yttria, 3% alumina), and the other having a crystalline boundary phase (8% yttria, 1% alumina) were tested using a novel split Hopkinson pressure bar technique with a momentum trap.
Defect Characterization in a CVD α-Si3N4
Authors: More Karren L.
Published: June 2020

Silicon nitride possesses an attractive combination of thermo-mechanical properties which makes it a strong candidate material for many structural ceramic applications. Unfortunately, many of the conventional processing techniques used to produce Si3N4, such as hot-pressing, sintering, and hot-isostatic pressing, utilize significant amounts of densification aids (Y2O3, Al2O3, MgO, etc.) which can ultimately lower the utilization temperatures to well below that of pure Si3N4. Chemical vapor deposition (CVD) is an alternative processing method for producing pure Si3N4. The CVD Si3N4 material examined in this study was supplied by Union Carbide. Deposition was performed at 1450°C and 1 Torr pressure using SiCl4 and NH3 as the reacting gases. The CVD methods used were similar to those described by Niihara and Hirai.
A Tem Study of Slip Systems in MoSi2/WSi2 Alloys
Authors: Maloy Stuart A.
Published: June 2020

MoSi2 has recently been investigated as a potential material for high temperature structural applications. It has excellent oxidation resistance up to 1700°C, a high melting temperature, 2030°C, and a brittle-to-ductile transition temperature at 900-1000°C. WSi2 is isomorphous with MoSi2 and has a body-centered tetragonal unit cell of the space group 14/mmm. The lattice parameters are a=3.20 Å and c=7.84 Å for MoSi2 and a=3.21 Å and c=7.88 Å for WSi2. Therefore, WSi2 was added to MoSi2 to improve its strength via solid solution hardening. The purpose of this study was to investigate the slip systems in polycrystalline MoSi2/WSi2 alloys.
Recent Advances in the Use of Cathodoluminescence for the Study of Geological Materials
Authors: Wright P. J. , Kearsley A.
Published: June 2020

CL examination of geological materials has in the past been performed using optical microscope based systems that have incorporated a vacuum chamber and electron flood gun attached to the sample plinth. The use of these for the study of materials such as quartz has been limited due to the low accelerating voltages (V ≤ 10 kV) employed coupled with extremely low photon collection efficiencies.

Electron microscope based systems are not subject to these limitation since collection optics offering efficiencies approaching 80% may be used. In addition, a range of accelerating voltages up to 10kV are routinely available. Until recently, only monochrome images displaying intensity variations were obtainable. It is now possible to obtain colour images displaying both wavelength and intensity variations across samples with a resolution that exceeds that of optical based systems.
Use of Storage Phosphors in Transmission Electron Microscopy
Authors: Boser O.
Published: June 2020

One of the most sophisticated analytical instruments, the transmission electron microscope (TEM), still records images on photographic plates. Attempts are made with video and charge coupled device (CCD) cameras to digitize the images and increase the sensitivity. An alternate technology to digitize images is based on storage phosphors widely used in medical x-ray computed radiography. For exposure to the electron beam, the storage phosphor plates are introduced in the microscope in place of conventional film. Digitization takes place in the read-out system that consists of a He/Ne laser that stimulates emission of blue light from the storage phosphor. The emitted blue light is proportional to the electron intensity that was incident at this point during exposure.
Andradite grain boundary secondary electron image generated by high-intensity electron beam in an electron microprobe
Authors: Liu D. R.
Published: June 2020

The calcium iron silicate Ca3Fe2Si3O12, which is also called andradite, is commonly used for simultaneous verification of wave-length spectrometers in the CAMECA SX-50 electron microprobe. However, an interesting phenomenon was observed that the grain boundaries, which would not show up under normal secondary electron (SE) imaging conditions, would delineate themselves at high beam current.

The SX-50 microprobe was operated in the voltage range of 10 to 20 kV. The probe current was varied from a few nA to a few hundred nA. The surface of the andradite sample was polished and carbon coated. When the beam current was only a few nA, the SE image showed only surface scratches and other surface defects such as pits (Fig. 1). However, if the current was increased to above 100 nA, the grain boundaries, which were hidden under the sample surface and thus invisible at low probe current, would then show up clearly (Figs. 2 and 3).
Environmental-cell TEM studies of catalyst particle behavior
Authors: Yao Nan , Spinnler Gerard E. , Kemp Richard A. , Guthrie Don C. , Dwight Cates R. , Mark Bolinger C.
Published: June 2020

In order to fully understand the general loss of activity for supported metal catalysts during the catalytic process, attempts of investigations of the microstructure and of observed structural changes of supported metal catalysts have been made by using environmental-cell TEM (EC-TEM). The EC-TEM used throughout the experiments reported here consists of a Philips-EM430 (300kV) TEM fitted with a Gatan environmental cell (E-cell). The key design feature is the ability to operate at high gas pressure in the specimen region while still maintaining high vacuum in the rest of the microscope. Fig.1 shows a sideview of the schematic arrangement of the E-cell (A). The standard Phi 1ips-EM430 twin pole pieces (B) have been modified by Gatan Inc. (with a resolution better than 0.34nm) in order to accept the E-cell. Specifically, a groove or “terrace” was machined around a diameter of the upper and lower pole pieces in order to seal with the top and bottom 0-rings (C) of the E-cell.
TEM study of supported catalyst clusters
Authors: Yao M. H. , Smith David J. , Wachs I. E.
Published: June 2020

In the present work we have studied two-dimensional metal oxide overlayers (Re2O7, WO3, etc) deposited on a second high-surface-area metal oxide substrate (TiO2, Al2O3, etc). The molecular structure of these surface metal oxide species has been extensively studied in the past decade by Raman spectroscopy and EXAFS because of their importance in catalytic applications. However, direct observations of these overlayers are still needed in order to better understand the basic properties of the overlayer species. High resolution electron microscopy(HREM) is one of the most commonly used methods for direct characterization of small catalyst particles. It can provide particle size distributions and information about particle disposition over the support materials. But it is generally believed that bright field imaging is only well suited for particles sizes larger than about 10 Å. For smaller metal particles on typical supports, HAADF in STEM has been proposed as a better choice.
Dislocation structure in melt-textured YBa2Cu3O7-x
Authors: Burke T. G. , Mitchell T. E.
Published: June 2020

Presently, there is considerable interest in the microstructure of melt-textured YBa2Cu3O7-x (MT-Y123) and its influence on flux pinning. Precipitates of Y2BaCuO5 are a common feature of the microstructure. In addition, the stacking faults associated with the insertion of an extra CuO plane may contribute to flux pinning. Thus far, the stacking faults reported have been isolated, i.e. not forming a network. There is reason to believe that an array of stacking faults would be beneficial in increasing the flux pinning, thus increasing the critical current density of MT-Y123.

The material studied was prepared by CPS Superconductor Inc. by holding a mixture of YBa2Cu3O7-X and Y2BaCuO5 Just above the peritectic temperature for 1 hour and quenching to just below the peritectic for 15 hours. Samples were then subjected to an oxygen annealing. It has large, highly textured grains which measure as much as 1cm in the a-b plane. TEM samples were cut parallel and perpendicular to the caxis. The samples were polished, dimpled and ion milled at 13° in a liquid nitrogen cold stage. A Philips CM30 microscope, operated at 300kV, was used in this study.
Microstructural characterization of YBa2Cu3O7-x thin films formed by metalorganic CVD
Authors: Lu P. , Huang W. , Chern C.S. , Li Y.Q. , Zhao J. , Kulesha G.A. , Gallois B. , Norris P. , Kear B. , Cosandey F.
Published: June 2020

The YBa2Cu3O7-x thin films formed by metalorganic chemical vapor deposition(MOCVD) have been reported to have excellent superconducting properties including a sharp zero resistance transition temperature (Tc) of 89 K and a high critical current density of 2.3x106 A/cm2 or higher. The origin of the high critical current in the thin film compared to bulk materials is attributed to its structural properties such as orientation, grain boundaries and defects on the scale of the coherent length. In this report, we present microstructural aspects of the thin films deposited on the (100) LaAlO3 substrate, which process the highest critical current density.

Details of the thin film growth process have been reported elsewhere. The thin films were examined in both planar and cross-section view by electron microscopy. TEM sample preparation was carried out using conventional grinding, dimpling and ion milling techniques. Special care was taken to avoid exposure of the thin films to water during the preparation processes.
Electron microscope studies on Nd2-xCexCuO4
Authors: Brigitte Krause H.
Published: June 2020

The crystal structure of Nd2-xCexCuO4, as determined from neutron powder diffraction and high resolution synchrotron radiation, has been reported in the literature. The space group was found to be Immm. The ratio of the tetragonal unit cell was reported to vary as a function of the compositions with two separate branches resulting in two different ratios for each composition. In addition, commensurate superlattices have been observed and related to ordering, of atoms or vacancies. The present work deals with electron diffraction data on the same samples used for the neutron diffraction work at Argonne National Laboratory. The samples were kindly supplied by Dr. Bogdan Dabrowski.
TEM study on freeze-fracture structure of smectic A* phase
Authors: Ihn K J. , Zasadzinski J. , Pindak R. , Patel J. , Goodby J.
Published: June 2020

Liquid crystals (LCs) with chiral molecules show helical structure. The most well known LC phase having helical structure is cholesteric, in which average direction of molecular axes rotates around a helical axis, as shown in Fig. 1. Two kinds of helical structures were found in smectic phases. The smectic A* phase contains the helical axis parallel to the smectic layers, and in the smectic C* phase, it is perpendicular. The Smectic A* phase was recently discovered in 1-methylheptyl 4'-[[(tetradecyloxyphenyl)propionyl]oxy]biphenyl-4-carboxylate, (+14P1M7). +14P1M7 changes its phase from isotropic melt to A* phase at 93°C and C* phase at 89.5°C, while a racemic mixture shows the untwisted A and C phase. The structure of smectic A* phase was predicted by Renn and Lubensky by hypothesizing a Twist grain boundary (TGB) phase in analogy with the Abrikosov phase in superconductors.
X-Ray Analysis of Cytochemical Reaction Products in Synaptic Areas
Authors: Wood J.
Published: June 2020

Specific cytochemical reactions have been instrumental in the illucidation of compounds within tissues, whether these compounds are hormones, enzymes, or molecules, such as certain nerve transmitter agents. Many cytochemical reaction products depend upon some complex, which is an electron dense deposit. Several types of cytochemical procedures can be used to visualize agents related to synaptic transmission at the junctional complex. One method which has been used with considerable success has been the cytochemical localization of biogenic amines (BAs), i.e., norepinephrine (NE) and dopamine (DA). For the past few years, a chrome complex formed with certain BAs and glutaraldehyde has been utilized to localize BAs at the electron microscopic level and the specificity of the reaction has been verified biochemically.
Surfaces of Mammalian Spermatozoa as Revealed in Platinum Replicas
Authors: Phillips David M.
Published: June 2020

Modification of available techniques for making platinum replicas of spermatozoa made it possible to visualize configurations of mitochondria, the outer surface of acrosomal membranes, the post-acrosomal region of sperm heads, and the exterior face of fibrous sheaths. Spermatozoa taken from the cauda epididymis of several mammalian species were treated 5 to 15 min with hypotonic (0.25 strength) Hank's BSS or 0.1% Triton X-100 in saline. After 1 hr. fixation in 3% collidine-buffered glutaraldehyde, spermatozoa were pelleted by slow speed centrifugation, and resuspended in water. Spermatozoa were then pelleted, resuspended in 0.5 ml of water, and allowed to settle onto a coverslip, pretreated by immersion in a 2 mg/ml solution of poly-L-lysine for 30 min and brief washing in water. Coverslips with attached sperm were dehydrated through graded alcohols to acetone and subjected to critical-point drying Replicas were made with an Edwards 306 coater by shadowing at 40° with platinum and 90° with carbon.
Photoelectron Microscopy And Quantum Yields Of Membrane Phospholipids.
Authors: Hayes Griffith O. , Dam Rudy J.
Published: June 2020

Contrast in photoelectron microscopy (PEM) depends on differences in the absolute photoelectron quantum yield defined as the number of electrons released divided by the number of incident photons. Recently, the photoelectron quantum yields of the amino acids and homopolymers were measured (1). These data define the range of quantum yields expected from membrane proteins. The other major membrane component is lipid and we report here the photoelectron quantum yields of the common phospholipids.

Synthetic L-α-dipalmitoylphosphatidylcholine (DPPC), L-α-dipalmitoylphosphatidylethanolamine (DPPE), L-α-dipalmitoylphosphatidylserine (DPPS), dipalmitoylphosphatidylglycerol (DPPG), and bovine heart diphosphatidylglycerol (DPG, or cardiolipin) were obtained commercially. DPPS, DPPC and DPPG were estimated to be at least 90% free of organic impurities by TLC analysis and DPPE and DPG migrated as single spots. Commercial, 99+% pure cholesterol was recrystallized from a chloroform:methanol (2:1 v/v) solution.
Protein Component in Sieve Elements of Quercus Rubra L.
Authors: Murmanis Lidija
Published: June 2020

At the earliest stage, P-protein in red oak sieve elements can be identified with the fine filaments embedded in the cytoplasm (Fig. 1), and they appear similar to the P-protein component in Cucurbita maxima at an early differentiation stage (1). At this time ribosomes (in a spiral configuration) and the rough ER are numerous and in intimate association with the filaments. As differentiation proceeds P-protein bodies are formed in which the filaments are randomly arranged (Fig. 2). Later the filaments become oriented parallel to one another (Fig. 1, at right) and are transformed structurally into tubules. Tubules aggregate into crystalline bodies (Figs. 3, 4) which resemble extruded nucleoli reported previously (2, 3). Individual tubules have a diameter of about 235A and a tripartite structure--60-70A thick electron-dense walls separated by an electron-transparent core. During the disintegration of sieve element protoplast the crystalline bodies disperse and tubules gradually change into fibrils.
Effects of Vincristine on Endothelial Microtubules in the Spinal Cord
Authors: Beggs John L. , Waggener John D. , Miller Wanda
Published: June 2020

Microtubules (MT) are versatile organelles participating in a wide variety of biological activity. MT involvement in the movement and transport of cytoplasmic components has been well documented. In the course of our study on trauma-induced vasogenic edema in the spinal cord we have concluded that endothelial vesicles contribute to the edema process. Using horseradish peroxidase as a vascular tracer, labeled endothelial vesicles were present in all situations expected if a vesicular transport mechanism was in operation. Frequently,labeled vesicles coalesced to form channels that appeared to traverse the endothelium. The presence of MT in close proximity to labeled vesicles sugg ested that MT may play a role in vesicular activity.
Subsurface Cisterns in the Dog Retina
Authors: Ladman J.
Published: June 2020

Since subsurface cisterns (SSCs) were first described in various neurons of the brain and spinal cord (1), several reports have appeared noting their presence in cells of the retina (2-8). SSCs have been reported to occur in photoreceptors in the guppy as well as in amacrine, bipolar and ganglion cell bodies in rabbit, squirrel and cat. This study extends observations of the SSC to the dog retina.

All retinas were immersed in Caulfield's fixative at 4°C for l½-2 hrs., stained en bloc with 1% magnesium uranyl acetate and embedded in Epon. SSCs consist of two apposed membranes, pentilaminar in structure and unusually electron dense, of variable length in profile (0.1-0.8μm) and found immediately subjacent to the plasmalemma of ganglion, amacrine and horizontal cells in the dog. They appear to be more prevalent in the ganglion cells, perhaps because of the larger surface area which the plasma membrane occupies in this particular cell type (Fig. 1). Immediately internal to the SSC is an element of the endoplasmic reticulum on the cytoplasmic surface of which can be seen an occasional ribosomal particle (Fig. 2).
Action of Uranyl Acetate on Glycogen in the Conducting Fibers of Dog Heart
Authors: Rybicka Krystyna , Damato Anthony N.
Published: June 2020

Controversy exists as to whether tissue glycogen is preserved or destroyed by treatment with uranyl acetate before dehydration. Some authors report that en bloc staining with uranyl acetate destroys glycogen (1), whereas others show preservation of glycogen following this staining procedure (2). Our study on conducting fibers of the dog heart suggests that there might be another factor involved in the preservation of several cytoplasmic structures which is vital to the understanding of glycogen preservation after the treatment with uranyl acetate. Fibers of conducting tissue are composed of a specific type of muscle cell containing large cytoplasmic areas filled with glycogen. Present observations were focused on these areas. Material was fixed in 3%. glutaraldehyde in phosphate buffer pH 7.2, post-fixed in 0S O4 and processed without (control) or with uranyl acetate.
Positional and Ultrastructural Alterations in Mitochondria Induced by Cod Liver Oil
Authors: Nopanitaya Waykin
Published: June 2020

Comparative studies on the intestinal mitochondria in either fasting or nonfasting young rats have been made earlier (1-3), and the differences in both polarization and morphology of mitochondria between fasting and control animals were noted. Also, evidence of mitochondrial mobilization and alterations was striking in the suckling rats after feeding a variety of nutrients such as water, saline, glucose, cow's milk, and corn oil. There has been no attempt to study the mitochondrial polarization and morphology in the intestinal epithelium of older rats during absorption of cod liver oil which has been highly recommended for studies on fat absorption (4).
Observations of Selective Attachment of Bacteria on Low-Grade Ore: Evidence for Direct-Contact Bacterial Leaching of Sulfide Minerals
Authors: Berry V.K. , Murr L.E.
Published: June 2020

The mechanism of bacterial leaching of sulfide minerals is not fully understood. There are two obvious mechanisms which have been proposed by Silverman and Ehrlich involving either indirect contact where Fe2+ ions oxidize metal sulfides while being reduced to Fe3+, or direct (physical) contact between the bacteria and the sulfide mineral under aerobic conditions. While the direct contact mechanism has been suggested by observations of bacterial acceleration of the oxidation rate of iron-free sulfides such as molybdenite (M0S2), chalcocite (Cu2S), and covellite (CuS)2-4, similar results have been demonstrated with pyrite (FeS2)5, but not with iron-containing sulfides such as bornite (Cu5FeS4) or chalcopyrite (CuFeS2). Recent work by Murr and Berry on the attachment of bacteria to low-grade chalcopyrite ore has, however, shown that bacteria seem to attach preferentially to the chalcopyrite phases; lending support to the direct contact mechanism.
Immunocytochemistry of Surface Changes in Ascaris Spermatozoa During Maturation
Authors: Bradley Ronald H. , Burghardt Robert C.
Published: June 2020

Substances removed from the male accessory gland in Ascaris have been shown to induce the immotile, spherical spermatozoa to become active ameboid cells. This change Indicates the advent of the sperm's competency to penetrate oocytes and therefore represents the final maturation of the spermatozoa. Although the morphological changes of these altered active spermatozoa have been well defined (1 and 2), the qualitative differences in the plasma membrane have not been followed in detail.

In the present study, antibodies were prepared against both the inactive and active Ascaris spermatozoa in female Australian white rabbits by weekly intramuscular injections of washed cell populations in combination with Freund's complete adjuvant.
Ultrastructural Characteristics of Platelets Separated from Plasma by ADP-Induced Aggregation
Authors: Shinoda B.A. , Hardison M.D. , Mohammad S.F. , Chuang H.Y.K. , Mason R.G.
Published: June 2020

The utilization of blood platelets in experimentation frequently requires their separation from blood and subsequent resuspension in media of known composition. Several methods are available for preparation of isolated platelets (1-3) by differential centrifugation or gel filtration, but most methods are tedious and time consuming. Often platelets obtained by use of such methods are in a state different functionally and ultrastructurally from that of platelets in plasma (4).

Recently Mohammad, Reddick, and Mason (5) reported a method in which platelets were separated from plasma by ADP-induced aggregation, washed several times, and then incubated in a carefully selected medium that resulted in deaggregation of platelets.
Ultrastructure of the Submandibular Gland of the Nine-Banded Armadillo
Authors: Ruby J. R.
Published: June 2020

It has been demonstrated previously that there are variations in the histochemical staining of the acinar cells in the submandibular gland of the armadillo (1). This suggested that the gland may be composed of several lobes, each of which contains different acinar cells. The present investigation confirms that the submandibular gland of the armadillo has a major and minor lobe. Both lobes deliver their secretions to the salivary bladder which is the dilated, proximal portion of the main duct of the gland. These lobes are very different, however, with respect to their histochemistry and ultrastructure.

The acinar cells of the major lobe stain lighter with PAS and alcian blue than those of the minor lobe. The demilune cells, however, exhibit a more intense reaction with these stains.
An Ultrastructural Comparison of Rat Lung Cells Grown in an Organotypic Culture System with Lung Tissue Found in the Whole Animal
Authors: Del Vecchio Peter J. , Dougherty Edward P. , Douglas William H. J.
Published: June 2020

This study describes the ultrastructure of an organotypic system prepared from rat fetal lung and compares it to lung in rat fetuses. The preparation of the organotypic system has been described elsewhere (1).

The organotypic systems in this study are prepared from 18-19 day fetal rat lung and spend two days in culture making the cells a total of 20-21 days old. The fine structure of the type II cells present in this system will be compared to the type II cells in fetal lung at 20-21 days gestation. Because the tissue organization of the organotypic system is more like the organization of fetal lung at an earlier stage (18-19 days gestation) , the cell to cell relationships of the organotypic system are compared to fetal lung tissue at this stage.

The histology of the organotypic system is similar to that of the fetal lung in its glandular stage (Fig. 1). The epithelial cells are all columnar and are surrounded by relatively undifferentiated mesenchyme.
Morphology of Abnormal Columns of Mesenchyme Cells in the Channel Catfish, Ictalurus Punctatus.
Authors: Henderson Vernon
Published: June 2020

During recent years , I have utilized several thousand young channel catfish or fry for several different studies. A few years ago, I noticed an increase in the number of adipose fins which showed fin ray-like structures. Fin rays in adipose fin of fish are rare. Assuming that the said structures were fin rays, I proceeded to study them, histologically. Upon microscopic examination, it was discovered that there was a complete absence of fin ray elements. In an effort to understand the structural changes responsible for the appearance of the ray-like elements , an electron microscopic analysis was undertaken.

Fish used in this study were secured from several different catfish farms located in the Grambling area; however, all seem to be linked to a common source from which brood stock had been purchased. The specimen used in this study ranged in length from 7.5 centimeters to 15.0 centimeters and were approximately four to six months in age.
A Morphological Study of the Nephridium of Lumbricus Terrestris: A Correlate of the Mammalian Nephron?
Authors: Anderson T.L. , Martin B.J.
Published: June 2020

The nephridium is a tubular excretory structure characteristic of coelomate invertebrates such as the annelid, Lumbricus terrestris (earthworm).

Nephridial function compares to that of the mammalian nephron in that they both perform four basic tasks: filtration, electrolyte resorption, fluid regulation, and excretion. In the flux created by the constant synthesis and breakdown of body constituents, excess materials are removed by filtration, detoxified, and excreted. In terrestrial animals, this process requires electrolyte secretion and resorption in order to maintain fluid balance.

In Lumbricus terrestris, there are (essentially) two nephridia per segment. Each appears to consist of one continuous tubule, differentiated into a series of three specialized loops: Short, Long, Thick (FIG. 1).
Junctional Systems in a Human Breast Carcinoma Cell Line (MCF-7).
Authors: Russo J. , Bradley R.H.
Published: June 2020

The epithelial cells of the normal human breast are tightly joined by junctional complexes composed of tight junctions, intermediate junctions, and desmosomes. Similar junctions have been reported in several types of breast carcinoma. In the present paper we report on the junctional systems observed in a human breast carcinoma cell line (MCF-7) (1).

MCF-7 cells cultured in Eagle's minimum essential medium, after 40-160 transfers were fixed simultaneously in glutaraldehyde and osmium according to the method of Hirsch and Fedorko (2), and were stained in uranyl acetate in block. After dehydration, the samples were detached with propylene oxide and embeded in Epon-Araldite (3). Sections were examined in an Hitachi HU-11A electron microscope after staining with uranyl acetate.
Activation of Macrophages by the Polysaccharide Glucan:T.E.M. Studies of Tumor Cell Destruction in BI6 Melanoma and in Humans.
Authors: Rowden G. , Proctor J.W. , Mansell P.W.A.
Published: June 2020

The polysaccharide glucan obtained from the cell wall of the yeast Saccharomyces cerevicea has been shown to possess important properties in respect to induction of local tumor regression in both animal models and in humans following intralesional injection.(Diluzio et al. 1974,Mansell et al. 1976.) Glucan is a long chain of glucopyranose units united by their β.I.3 glycosidic linkages.(Fig.I)The details of how glucan brings about its affect on the monocyte/macrophage cell type are largely unknown but the tumor regression appears to involve phagocytosis of tumor cells after the macrophages have become activated as a result of ingesting glucan.Other mechanisms of tumor cell destruction involving contact-mediated lysis of either immune specific or non specific forms are possible but have not been described in this system.The typical result of the interactions between tumor cells and macrophages is the production of a cold abscess.
Electron Microscopic Examination of the Mummichog (Fundulus Heteroclitus) Respiratory Epithelium Following Acute Exposure to Mercury
Authors: Klaunig J. , Koepp S.
Published: June 2020

Although light microscopical studies on both the rainbow trout (1) and mummichog (2) have revealed extensive trauma of the gill epithelium following acute exposure to mercuric compounds, the absence of comparable ultrastructural data has prevented accurate interpretation of subcellular events stemming from uptake of this toxicant. This paper describes current progress in the description of mercury-induced changes in epithelial fine structure and function. The mummichog was selected as the test fish because of its extensive use in compensatory physiological studies (3), as well as prior pathological investigations involving heavy metals (4). Male fish (3.3-3.5 g) were incubated for 96 hours in one of three toxicologically-significant dosages of mercuric chloride (1.0, 2.0, and 4.O ppm). Surviving fish at each dosage were subsequently sacrificed and the respective gill tissues fixed for two hours in 2.5 % phosphate-buffered glutaraldehyde (pH 7.3) at 4°c.
In Vivo Growth and Development of Equine Adenovirus in the Lung of Arabian Horse
Authors: Kim J. C. S.
Published: June 2020

Arabian foals are more susceptible to adenovirus infection because of the generalized immunodeficiency resulting from a genetic defects (1, 2) . The disease is characterized by pneumonia, intermittent fever, and high mortality. Severe lymphopenia has accompanied the fatal infection in foals (3). The growth and multiplication of adenoviruses, in general, has been studied mainly in suspension cultures of KB, Hela and other renal tissue culture system (4). Whether a similar multiplication cycle is occurring in vivo has not been determined.

Pulmonary tissues from a necropsied arabian horse were processed for electron microscopy. Thick sections of infected lung show numerous intranuclear inclusion bodies in the bronchial epithelium. Serial thin sectioning of the same area indicates occurrence of various developmental stages of adenovirus multiplication. This report summarizes our morphologic observation made in vivo and compare to what is known in vitro system.
The Use of Lead and Uranyl Ions As A Stain in Scanning Electron Microscopy
Authors: Mumaw V. R. , Goheen M. P. , Munger B. L.
Published: June 2020

Cellular components can be identified in cryofractured surfaces of osmium impregnated tissue examined in the scanning electron microscope (SEM). The present study compares the staining properties of uranyl and lead ions used to selectively enhance the definition of cell organelles. Tissues used for this study were liver, kidney and testis from normal rats. All of the tissue in this study was treated with osmium-thiocarbohydrazide-osmium (OTO) as described by Munger and Mumaw (1). Following the OTO treatment some tissues were placed in 1% aqueous uranyl acetate for 4 hrs. at room temp. Tissue stained with lead was placed in a Millonig's lead hydroxide solution for 2 hrs. Some tissue blocks were stained with uranyl acetate for 4 hrs. followed with 2 hrs. staining in lead hydroxide. Following each staining period the tissue was rinsed several times with distilled water before proceeding with the next step.
The use of a Bent Grid to Improve the take-Off Angle for Electron Probe Analysis
Authors: Philpott Delbert E. , Leaffer David
Published: June 2020

There are certain advantages for electron probe analysis if the sample can be tilted directly towards the detector. The count rate is higher, it optimizes the geometry since only one angle need be taken into account for quantitative analysis and the signal to background ratio is improved. The need for less tilt angle may be an advantage because the grid bars are not moved quite as close to each other, leaving a little more open area for observation. Our present detector (EDAX) and microscope (Philips 300) combination precludes moving the detector behind the microscope where it would point directly at the grid. Therefore, the angle of the specimen was changed in order to optimize the geometry between the specimen and the detector.
Tem Studies of Hen's Perivitelline Membrane Hydrolysis by Cock Sperm in Vitro
Authors: Bakst M. R.
Published: June 2020

In a manner analogous to the way in which the zona pellucida envelops the mammalian ovum, a single acellular investment, the perivitelline membrane (PM), uniformly covers the hen's ovum at the time of ovulation. It consists of a fiberous latticework 2-4μm in width with interstices occupied by a porous ground substance (Figs. 1,2). The PM overlying the blastodisc is preferentially hydrolyzed in vitro by cock sperm (1) or by partially purified cock sperm acrosin (2). With either agent the PM overlying the remainder of the ovum requires longer incubation times for hydrolysis.

Transmission electron microscopy of blastodisc and non-blastodisc regions of ova removed from the body cavity immediately after ovulation and incubated with sperm in modified Krebs-Ringer solution for 10-15 min. clearly demonstrates this breakdown.
The Effect of Intraperitoneal Colchicine Injections on Neurotubules of Myelinated Axons
Authors: Bell M.
Published: June 2020

The transport of axoplasmic material away from the cell body of the neuron was first clearly documented by Weiss and Hiscoe in 1948. (1) This transport phenomenon was later investigated by Droz and LeBlond (2) with radioactive tracers and has been sufficiently confirmed by workers in many laboratories. (3,4,5) It is currently believed that colchicine can effectively inhibit axonal transport (6,7,8), and does so by binding to the neurotubular subunit, tubulin.(9,10) Previous studies showed that topical application of colchicine to peripheral nerves (subepineural injections) or to the brain (intracisternal injections) have changed neurotubular ultrastructure. The purpose of this study was to examine the effect of whole body injections of colchicine on the number of neurotubules in treated axons.
A New Method for Heating a Single-Sideband Aperture
Authors: Hayward S. B.
Published: June 2020

Single-sideband imaging has been proposed as a method for achieving full contrast transfer over all spatial frequencies, thus avoiding the zeroes . and regions of reversed contrast in the double-sideband transfer function. The single-sideband method has been used to discriminate between light and heavy atoms by separating phase and amplitude contrast, but a severe restriction on the method is the charging caused by rapid contamination of the half-aperture as it approaches the zero-order beam. This contamination problem has been solved by the use of an aperture strip heated resistively to temperatures up to 170°C. The main problem with this technique is that the heating current passes through the most sensitive part of the objective lens, thus necessitating a current stability of 5x10-6.
Sem/X-Ray Applications to the Forensic Science Field
Authors: Culbreth K.
Published: June 2020

The introduction of scanning electron microscopy and energy dispersive x-ray analysis to forensic science has provided additional methods by which investigative evidence can be analyzed. The importance of evidence from the scene of a crime or from the personal belongings of a victim and suspect has resulted in the development and evaluation of SEM/x-ray analysis applications to various types of forensic evidence. The intent of this paper is to describe some of these applications and to relate their importance to the investigation of criminal cases.

The depth of field and high resolution of the SEM are an asset to the evaluation of evidence with respect to surface phenomena and physical matches (1). Fig. 1 shows a Phillips screw which has been reconstructed after the head and shank were separated during a hit-and-run accident.
Electron-Channelling Patterns: Principles and Techniques
Authors: Joy David C.
Published: June 2020

In a crystalline solid the regular arrangement of the lattice structure influences the interaction of the incident beam with the specimen, leading to changes in both the transmitted and backscattered signals when the angle of incidence of the beam to the specimen is changed. For the simplest case the electron flux inside the specimen can be visualized as the sum of two, standing wave distributions of electrons (Fig. 1). Bloch wave 1 is concentrated mainly between the atom rows and so only interacts weakly with them. It is therefore transmitted well and backscattered weakly. Bloch wave 2 is concentrated on the line of atom centers and is therefore transmitted poorly and backscattered strongly. The ratio of the excitation of wave 1 to wave 2 varies with the angle between the incident beam and the crystal structure.
Applications of Electron Channeling to Materials Science
Authors: Davidson D. L.
Published: June 2020

The phenomena of electron channeling have been and are being used in materials science and engineering technology. Since the specimen preparation relative to transmission electron microscopy (TEM) is relatively simple (no thinning required), channeling may be used, in a few cases, in place of TEM. The other uses for channeling are those for which no other technique is applicable. In deciding on whether to apply channeling to a particular problem, several things must be considered: Are the crystals to be channeled relatively free of defects (otherwise channeling patterns cannot be obtained)? If so, are the crystals large enough to be compatible with the spot size attainable with available instruments (spot sizes below about 5-10 μmare difficult to achieve on most instruments)? Is sufficient information available in the channeling patterns for the rocking angle to be used (small spot sizes require small rocking angles because of lens aberrations)? Can specimens be properly prepared (heat treatments, surface polishing, electropolishing,etc.)? These considerations require that the metallurgical structures being used must be relatively simple; e.g., martensitic steels and most pearlitic structures are not suitable.
In-Situ Investigation of Fatigue Deformation by Sem Methods
Authors: Weiss B. , Stickler R.
Published: June 2020

The damage which accumulates during cyclic deformation of metals and alloys is characterized by internal dislocation reactions and by the formation of “persistant slip bands” in surface near regions. The latter are thought to contribute to the nucleation of microcracks which propagate and finally lead to fatigue failure.

The determination of the microstructural and topographical changes occuring progressively during fatigue exposure is of considerable scientific and technical interest. A detailed investigation of the kinetics of these changes requires in-situ examination which are best carried out with a SEM due to the large depth of focus, the wide magnification range, and the possibilities of electronic signal processing and video recording.
Scanning Electron Microscopy of Carburized Thoriated-Tungsten Directemitting Cathodes
Authors: Amy J. A. , Alcorn R. A. , Phillips B. F.
Published: June 2020

Distributions of elements in carburized W-1% Th02 wires from cathodes of high-power electron tubes after 10 and 3500 hr operation have been determined by ion microscopy (1); some microstructural features of such wires are reported here.

Carburization of the wires examined had taken place to a depth of about one-eighth their 10-mil diameter (Figure 1). Longitudinal cracks with short circumferential excursions appear to be common in these wires, although this Figure shows an unusually bad case. Die marks from wiredrawing were also evident on all wires.

At their outer ends the cracks had the same surface hillocks as the emissive surfaces (Figure 2), suggesting that they may have existed before carburization began. At their roots, some cracks showed smooth fracture surfaces (Figure 3), suggesting that crack extension might have occurred later: as the carburized layer becomes thicker, the outermost portions are placed under ever-increasing tensile loading because of the volume increase on passing from metal to carbide.
Scanning Electron Microscopy in Hybrid Microelectronics
Authors: Khadpe S. , Faryniak R.
Published: June 2020

The Scanning Electron Microscope (SEM) is an important tool in Thick Film Hybrid Microcircuits Manufacturing because of its large depth of focus and three dimensional capability. This paper discusses some of the important areas in which the SEM is used to monitor process control and component failure modes during the various stages of manufacture of a typical hybrid microcircuit.

Figure 1 shows a thick film hybrid microcircuit used in a Motorola Paging Receiver. The circuit consists of thick film resistors and conductors screened and fired on a ceramic (aluminum oxide) substrate. Two integrated circuit dice are bonded to the conductors by means of conductive epoxy and electrical connections from each integrated circuit to the substrate are made by ultrasonically bonding 1 mil aluminum wires from the die pads to appropriate conductor pads on the substrate. In addition to the integrated circuits and the resistors, the circuit includes seven chip capacitors soldered onto the substrate. Some of the important considerations involved in the selection and reliability aspects of the hybrid circuit components are: (a) the quality of the substrate; (b) the surface structure of the thick film conductors; (c) the metallization characteristics of the integrated circuit; and (d) the quality of the wire bond interconnections.