bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of light intensity on the ultrastructure of the filamentous cyanobacterium,Anabaena variabilis
Authors: Bricker C. S. , Barnum S. R. , Huang B. , Jaworskl J. G.
Published: June 2020

Cyanobacteria are Gram negative prokaryotes that are capable of oxygenic photosynthesis. Although there are many similarities between eukaryotes and cyanobacteria in electron transfer and phosphorylation during photosynthesis, there are two features of the photosynthetic apparatus in cyanobacteria which distinguishes them from plants. Cyanobacteria contain phycobiliproteins organized in phycobilisomes on the surface of photosynthetic membrane. Another difference is in the organization of the photosynthetic membranes. Instead of stacked thylakolds within a chloroplast envelope membrane, as seen In eukaryotes, IntracytopIasmlc membranes generally are arranged in three to six concentric layers. Environmental factors such as temperature, nutrition and light fluency can significantly affect the physiology and morphology of cells. The effect of light Intensity shifts on the ultrastructure of Internal membrane inAnabaena variabilisgrown under controlled environmental conditions was examined. Since a major constituent of cyanobacterial thylakolds are lipids, the fatty acid content also was measured and correlated with uItrastructural changes. The regulation of fatty acid synthesis in cyanobacteria ultimately can be studied if the fatty acid content can be manipulated.
Elemental composition of soybean seeds
Authors: Yaklich R. W. , Chaney N. , Vigil E. L. , Wergin W. P.
Published: June 2020

The soybean (Glycine max L. Merr.) seed coat is the terminal maternal tissue that supplies the developing embryo with nutrients. Between the embryo and seed coat, where this transfer presumably occurs, we have found (1,2) a specialized convex area (antipit) on the inside surface of the soybean seed coat that is opposed by a concave area (pit) on the surface of the cotyledon. The cells of this pit-antipit complex are larger than those of the surrounding tissue. Furthermore, the aleurone and cone cells of the antipit have many characteristics of secretory cells. Previous data about these structures has been cytological; very limited biochemical information is knownabout the area. This paper presents preliminary data about the elemental content of these surfaces in the mature seeds of domesticated soybean, G. max and a close relative, G. soja.

The seed was dissected into right and left cotyledons; the right cotyledon was used for all microscopy and X-ray analysis. The seed coat was then separated from the cotyledon and excess tissue was removed.
Effect of verapamil on cytoplasmic distribution of granules and microfilaments in amphibian urinary bladder
Authors: Mia A.J. , Oakford L.X. , Yorio T.
Published: June 2020

The amphibian urinary bladder has been used as a ‘model’ system for studies of the mechanism of action of antidiuretic hormone (ADH) in stimulating transepithelial water flow. The increase in water permeability is accompanied by morphological changes that include the stimulation of apical microvilli, mobilization of microtubules and microfilaments and vesicular membrane fusion events . It has been shown that alterations in the cytosolic calcium concentrations can inhibit ADH transmembrane water flow and induce alterations in the epithelial cell cytomorphology, including the cytoskeletal system . Recently, the subapical granules of the granular cell in the amphibian urinary bladder have been shown to contain high concentrations of calcium, and it was suggested that these cytoplasmic constituents may act as calcium storage sites for intracellular calcium homeostasis. The present study utilizes the calcium antagonist, verapamil, to examine the effect of calcium deprivation on the cytomorphological features of epithelial cells from amphibian urinary bladder, with particular emphasis on subapical granule and microfilament distribution.
Ultrastructural changes in avian toxic heterophils
Authors: Latimer S. , Steffens W.L. , Goodwin Mark
Published: June 2020

In mammals, morphologic changes in peripheral blood neutrophils are often reflections of bacterial infection and severe inflammation. These light microscopic changes as evidenced by Romanowsky staining may include appearance of Döhle bodies, toxic granules, vacuolation, and cytoplasmic basophilia. Cells exhibiting such changes are referred to as “toxic” neutrophils. Studies of ultrastructural alterations in toxic neutrophils are reported and well-documented in humans (1) and dogs (2). Detailed controlled investigations of leukocyte changes in response to inflammation in birds are lacking. It was the purpose of this study to document toxic changes induced by intramuscular turpentine injection in the equivalent avian cell, the heterophil.

Young adult female White Leghorn chickens were obtained and divided into 2 groups, one receiving injection with 1 ml of filter-sterilized commercial grade turpentine in the right breast muscle, and the other (controls) receiving a similar volume of sterile saline.
Immunogold labeling of bluetongue virus in cryosections fromCulicoides variipennis(Coquillett) salivary gland
Authors: Nunamaker R. A. , Wick B. C. , Nunamaker C. E.
Published: June 2020

When an arbovirus enters its arthropod host during a viremic blood meal it quickly reaches the midgut where virus penetration of the host parenchyma and infection of epithelial cells apparently occur. Subsequently, viral particles enter the arthropod's hemolymph and are transported to other tissues which may then become infected. Previous studies have demonstrated that when the arbovirus reaches the salivary glands it increases in titer and persists over long periods, often throughout the life of the vector.

It is this persistent presence and associated continual shedding of virus into saliva which is one reason that certain arthropods are extremely efficient biological vectors.

Culicoides variipennis(Coquillett) is probably the most economically important species of biting midge in the U.S. due to its involvement in the transmission of bluetongue (BT) disease of sheep, cattle and ruminant wildlife. Although there have been numerous electron microscopic studies of many mosquito-borne viruses in their natural hosts, virtually nothing is known about the replicative cycle of BTV in the salivary glands of its primary vector.
Evaluation of erythrocyte membranes by immunocytochemical techniques following the transfusion of incompatible blood
Authors: Hathaway T. K. , Adams J. L. , Heckman C.
Published: June 2020

The hemolytic transfusion reaction (HTR) is the most formidable complication in blood transfusion therapeutics. Immune clearance and destruction of red blood cells (RBC) following infusion of incompatible blood have generally been thought to involve opsonic proteins, i.e., immunoglobulins (IgG, IgM) and complement. Fibronectin (FN), a multifunctional plasma and tissue protein, participates in many significant biological and pathophysiological activities and has opsonic characteristics. Plasma fibronectin (PFN) has been associated with acute HTR and the use of dogs as effective models for HTR research has been established. By using immunocytochemical techniques, this study proposed to localize and identify opsonic proteins coating and contributing to lysis of RBC during an acute HTR.

Three dogs were infused with heterologous RBC. Plasma hemoglobin (Hb), PFN, IgG, IgM, and complement (C3) were measured to assess the HTR. RBC collected at timed intervals before and after the infusion were viewed by fluorescent and electron microscopy using fluorescein isothiocyanate conjugate and immunogold staining.
The orientation of sickle hemoglobin fibers within fascicles
Authors: Miller Christopher A. , Carragher Bridget , McDade William A. , Josephs Robert
Published: June 2020

Highly ordered bundles of deoxyhemoglobin S (HbS) fibers, termed fascicles, are intermediates in the high pH crystallization pathway of HbS. These fibers consist of 7 Wishner-Love double strands in a helical configuration. Since each double strand has a polarity, the odd number of double strands in the fiber imparts a net polarity to the structure. HbS crystals have a unit cell containing two double strands, one of each polarity, resulting in a net polarity of zero. Therefore a rearrangement of the double strands must occur to form a non-polar crystal from the polar fibers. To determine the role of fascicles as an intermediate in the crystallization pathway it is important to understand the relative orientation of fibers within fascicles. Furthermore, an understanding of fascicle structure may have implications for the design of potential sickling inhibitors, since it is bundles of fibers which cause the red cell distortion responsible for the vaso-occlusive complications characteristic of sickle cell anemia.
Hyperglycogenic secondary center cells in rat femurs
Authors: Shepard Nora , Mitchell Nelson
Published: June 2020

The cells forming the secondary center have been described and compared to the hypertrophic chondrocytes of the primary growth plate (ref.I,2). In an attempt to clarify the nature of the vacuolization and associated cell hypertrophy reported to also take place within the chondrocytes of the secondary center prior to the onset of ossification an attempt to improve chondrocyte morphology was made. Glutaraldehyde fixation followed by buffered osmium was compared to tissue fixed with potassium ferrocyanide reduced osmium.

Cartilage slices from 5-7 day rats (distal femur) were fixed in 2% glutaraldehyde/0.1M Na phosphate pH 7.4 (2 hrs.); rinsed in 0.1M N phosphate buffer plus 0.1M sucrose (15. min.); post fixed in 1.5% potassium ferrocyanide in aqueous OSO4 or in 2% OSO4/0.1M Na phosphate (2 hrs.); rinsed in 0.1M Na acetate (pH 6.3); en bloc stained in .25% uranyl acetate/0.1M Na acetate; dehydrated in alcohol and Spurr embedded.
The quantitation of volume, surface, and length using classical stereological principles
Authors: Basqen John M.
Published: June 2020

Biologists and material scientists are often confronted with the problem of quantitating the volume, surface, or length of certain components contained within a reference structure. For example, the biologists might be interested in knowing the volume of mitochondria within a liver cell. A mineralogist might be interested in knowing how much gold 1s contained within a certain rock sample. To obtain structural Information about the component (mitochondria, gold) within the reference space (liver cell, rock sample) sections are made through the 3-dimensional reference space and measurements are made on the 2-dimensional sections or micrographs of the sections.

Stereology is the science of mathematical methods relating 3-dimensional parameters defining a structure to measurements obtained from 2-d1mens1onal samples of the structure, such as sections or micrographs.
Amorphous solidification in submicron droplets of pure metals
Authors: Kim Yeon-Wook
Published: June 2020

Many techniques have been developed for synthesis of amorphous materials. The most successful method used to form metallic glasses from melts has been to alloy pure metals with other elements in order to decrease the thermodynamic and kinetic driving force for crystallization. There are two common groups of alloying systems that form glass effectively; metal-metalloid alloys and intertransition metal alloys. These alloys would be readily solidified as an amorphous phase by splat quenching, metal spinning, or laser surface melting. In the 1970's, pure metals such as Cr, Fe, and Mn were made amorphous in thin film form by evaporation of metal vapors onto a very cold substrate (4 K). Recently, Kim, Lin, and Kelly discovered amorphous phases in rapidly solidified droplets of pure iron and alloys of iron and nickel. The submicron droplets of liquid metal were produced and cooled in free fright through a vacuum chamber.
Solid-state amorphization by electron irradiation
Authors: Luzzi D.E.
Published: June 2020

When certain intermetallic compounds are irradiated with ballistic electrons at low temperatures, the crystal becomes unstable and transforms into an amorphous phase. This electron irradiation induced crystalline to amorphous (C-A) transition is one of a recently discovered class of amorphization processes which occur in the solid state [1]. The relative simplicity of electron-matter interactions, and the ability to follow the transition inside the microscope, make the electron induced C-A transition ideal for the study of these amorphization processes.

A bright field image sequence which depicts several features of the C-A transition is shown in the figure. In this example, CuTim was irradiated with 2 MeV electrons at 191 K (9.2 x 1023 e/m2-s; 5.5 x 10-3 dpa/s). The arrows mark a fixed position. In the images, taken after different irradiation times (a:30s, b:60s c:300s), the transition is evident from the distortion of the bend contour around the irradiated area.
Alpha-decay damage and the aperiodic structure of pyrochlore
Authors: Lumpkin G. R. , Ewing R. C.
Published: June 2020

Alpha-decay damage in minerals which contain U and Th involves two separate damage processes: a high energy (4-5 MeV) alpha particle with a range of 10,000 nm displaces several hundred atoms creating Frenkel defects near the end of die track; and a recoil atom (0.1 MeV) with a range of 10 nm produces several thousand atomic displacements creating “tracks” of disordered material. Pyrochlore group minerals are suitable for the study of alpha-decay damage because they contain variable amounts of U and Th such that the accumulated dose spans the transition from the crystalline to the fully aperiodic, “metamict” state.

More than 50 natural pyrochlores were characterized by a number of experimental techniques. Electron microprobe analyses were obtained using a JEOL 733 Superprobe operated at 15 KV and 20 nA. X-ray diffraction studies were completed using an automated Scintag powder diffractometer.
Absolute determination of surface atomic concentration by reflection electron energy-loss spectroscopy
Authors: Wang Z. L. , Egerton R.F.
Published: June 2020

Reflection electron energy-loss spectroscopy (REELS) has been demonstrated as a useful technique for analyzing the structure of crystal surfaces. It is a combination of EELS with reflection electron microscopy (REM) performed in a transmission electron microscope. Here, we suggest a basic theory and experiment which enable REELS to determine absolutely the atomic concentration (atoms per unit volume) at a crystal surface.

In the RHEED case, not all the incident electrons will travel an equal distance within the sample (fig. 1A). Under the surface-resonance condition, the incident electrons are propagating parallel or nearly parallel to the crystal surface. Then a mean travelling distance (MTD) D can be defined, along which the excitation of atomic inner shells is equivalent to the total excitation of the atomic inner shells in the dynamical scattering (fig. IB). It can be found from the analysis of experimental data as:

(1)
Quantitative lorentz microscopy of NdFeB magnets
Authors: Mishra Raja K.
Published: June 2020

It is now well established that quantitative measurement of domain wall width using Lorentz electron microscopy is nontrivial. The usual technique of extrapolating divergent wall image widths of over-focussed or under-focussed Fresnel images suffers from serious errors since it is based on geometrical considerations and does not take into account the wave optical effects of electron scattering in the microscope. These errors are overcome if one supplements the measurements with image computation for the specific electron optical system and the specimen configuration. Another way of circumventing the errors is by using Differential Phase Contrast Microscopy in a Scanning Transmission Microscope which unfortunately requires instrumentation changes in the electron source and the electron detection system. In this paper we describe a simple method of calculating quantitative values of domain wall energy and domain wall width from Fresnel images obtainable in any standard transmission electron microscope.
Intermetallic formation with indium solder
Authors: Darveaux Robert , Turlik Iwona , Hren John
Published: June 2020

This study investigates metallurgical interactions between indium solder and thin film metal layers. Intermetallic formation is an important reliability concern with solder joints because the compounds are typically brittle phases that act as stress concentrators during thermal and power cycling of a device [1], Experiments were carried out for the thin film structure shown schematically in Figure 1. For convenience, 80 nm of Cr and 1.0 μm of Cu were e-beam evaporated on a Si substrate, followed by electroless plating ∼1μm Niklad 752 nickel (1%B). The substrate was diced, then tinned on a hot plate @ 180+/- 5*C using Blackstone #1452 flux. The solder was molten for times of 30,60,120, and 240 sec. Indium was etched away in concentrated HC1 to reveal the intermetallic formation. Shown in Figure 2 is a rod-like eutectic found in the solder bulk. Debye-Scherrer x-ray powder diffraction and energy dispersive x-ray spectrometry were used to identify the phases as In/ϕ-InCu.
Defects in β-SiC thin films grown on α-SiC substrates
Authors: More Karren L.
Published: June 2020

Beta-SiC is an ideal candidate material for use in semiconductor device applications. Currently, monocrystalline β-SiC thin films are epitaxially grown on {100} Si substrates by chemical vapor deposition (CVD). These films, however, contain a high density of defects such as stacking faults, microtwins, and antiphase boundaries (APBs) as a result of the 20% lattice mismatch across the growth interface and an 8% difference in thermal expansion coefficients between Si and SiC. An ideal substrate material for the growth of β-SiC is α-SiC. Unfortunately, high purity, bulk α-SiC single crystals are very difficult to grow. The major source of SiC suitable for use as a substrate material is the random growth of {0001} 6H α-SiC crystals in an Acheson furnace used to make SiC grit for abrasive applications. To prepare clean, atomically smooth surfaces, the substrates are oxidized at 1473 K in flowing 02 for 1.5 h which removes ∽50 nm of the as-grown surface. The natural {0001} surface can terminate as either a Si (0001) layer or as a C (0001) layer.
Tetragonal microdomains in partially reduced zirconia
Authors: Kim Y. M.
Published: June 2020

Tweed structure often forms when ZrO2-Y2O3 alloy is cooled at a moderate rate through the cubic plus tetragonal two-pnase field. Hannink1 and Ishizawa et al. have explained that tweed character comes from the strain field around fine tetragonal precipitates in a cubic matrix. Sakuma et al. have reported similar structures after isothermal annealing at appropriate temperature and composition and explained in terms of spinodal decomposition. But, Lanteri et al. have suggested that the matrix have transformed displacively to t-symmetry once sample is cooled rapidly, observing antiphase boundaries(APB's) in DF with [112] type reflections. There is still uncertainty on the microstructure of tweed structures. This study presents the microstructures obtained from vacuum sintered ZrO2-5mol Y2O3, that show fine tetragonal microdomains with APB's in a cubic matrix.

A 10mm dia. by 2mm thick pellet was cold-pressed from a ZrO2-5mol % Y2O3 powder, sintered at 2000°C for 2 h in vacuum, and fast-cooled (from 2000°C to 1100°C in 4 min.). Then, a 0.7mm thick disc was cut, sintered again at 2000°C for 4 h and fast cooled. The specimens were reduced and were black in color.
Antiphase domain boundaries in liquid-phase sintered aluminum nitride
Authors: Youngman R.A.
Published: June 2020

Liquid phase sintering of aluminum nitride is currently being developed for the production of Integrated circuit substrates In high power applications due to the high Inherent thermal conductivity of AIN. The sintering is usually conducted with oxide additives which form low melting eutectic compositions with AIN and its ever-present oxide surface layer. In this study Y2O3 (1-2wt/o) has been utilized for liquid phase formation where the eutectic compositions Y3Al5O12, YAlO3, and Al2Y4O9 form by reaction with “A12O3” on the surface of the AIN. The AIN particles themselves will contain oxygen (˜l-2wt/o)and this is also availible for reaction although not as readily since It has been accomodated In the bulk crystal. Since It has been established that the thermal conductivity of the resulting ceramic is controlled by the lattice oxygen content, which In turn controls the number of aluminum vacancies due to charge compensation, It Is important to understand the defect structure developed during sintering.
Observations of dislocation interactions with recrystallized grain boundaries
Authors: Price C. W.
Published: June 2020

Little evidence exists on the interaction of individual dislocations with recrystallized grain boundaries, primarily because of the severely overlapping contrast of the high dislocation density usually present during recrystallization. Interesting evidence of such interaction, Fig. 1, was discovered during examination of some old work on the hot deformation of Al-4.64 Cu. The specimen was deformed in a programmable thermomechanical instrument at 527 C and a strain rate of 25 cm/cm/s to a strain of 0.7. Static recrystallization occurred during a post anneal of 23 s also at 527 C. The figure shows evidence of dissociation of a subboundary at an intersection with a recrystallized high-angle grain boundary. At least one set of dislocations appears to be out of contrast in Fig. 1, and a grainboundary precipitate also is visible. Unfortunately, only subgrain sizes were of interest at the time the micrograph was recorded, and no attempt was made to analyze the dislocation structure.
TEM examination of 2014-SiC metal matrix composite
Authors: Burke M. G. , Gungor M. N. , Liaw P. K.
Published: June 2020

Aluminum-based metal matrix composites offer unique combinations of high specific strength and high stiffness. The improvement in strength and stiffness is related to the particulate reinforcement and the particular matrix alloy chosen. In this way, the metal matrix composite can be tailored for specific materials applications. The microstructural characterization of metal matrix composites is thus important in the development of these materials. In this study, the structure of a p/m 2014-SiC particulate metal matrix composite has been examined after extrusion and tensile deformation.

Thin-foil specimens of the 2014-20 vol.% SiCp metal matrix composite were prepared by dimpling to approximately 35 μm prior to ion-milling using a Gatan Dual Ion Mill equipped with a cold stage. These samples were then examined in a Philips 400T TEM/STEM operated at 120 kV. Two material conditions were evaluated: after extrusion (80:1); and after tensile deformation at 250°C.
The influence of heat treatment on the fiber/matrix interface in a SiC-reinforced glassceramic
Authors: Bischoff E. , Sbaizero O.
Published: June 2020

Fiber or whisker reinforced ceramics show improved toughness and strength. Bridging by intact fibers in the crack wake and fiber pull-out after failure contribute to the additional toughness. These processes are strongly influenced by the sliding and debonding resistance of the interfacial region. The present study examines the interface in a laminated 0/90 composite consisting of SiC (Nicalon) fibers in a lithium-aluminum-silicate (LAS) glass-ceramic matrix. The material shows systematic changes in sliding resistance upon heat treatment.

As-processed samples were annealed in air at 800 °C for 2, 4, 8, 16 and 100 h, and for comparison, in helium at 800 °C for 4 h. TEM specimen preparation of as processed and annealed material was performed with special care by cutting along directions having the fibers normal and parallel to the section plane, ultrasonic drilling, dimpling to 100 pm and final ionthinning. The specimen were lightly coated with Carbon and examined in an analytical TEM operated at 200 kV.
Atomic growth mechanisms for lamellar structures
Authors: Fonda R.W. , Black L.R. , Shiflet G.J.
Published: June 2020

The pearlite transformation product is composed of alternating plates resulting from a eutectoid transformation whereas the discontinuous or cellular transformation is also composed of alternating plates due to relief of supersaturation. This paper will describe the relationship between the growth interface and interlamellar structure that results from the pearlite and cellular structures. Some important similarities will be noted that relate to both types of phase transformations.

The Cu—4w/o Ti alloy was made by induction melting high purity materials and homogenizing. Samples were then solutionized at 900 C and isothermally transformed at 740 C for 60 m. Details of the experimental procedure for the Fe—.8w/o C—12 w/o Mn alloy are given elsewhere.

Cellular precipitation in Cu—Ti alloys consists of the synchronous growth of lamallae of less saturated fcc Cu and an ordered orthorhombic Cu4Ti β phase. The conjugate habit planes between the depleted matrix and β phase is (010)β//(111)α with [001]β//[110]α.
Hydride formation in pure titanium
Authors: Vanderwalker D. M.
Published: June 2020

Hydrogen embrittlement of metals is a subject of importance because it is often the cause of catastrophic failure. The loss in ductility occurs when the hydrogen concentration exceeds a percent or few. In titanium, the embrittlement effect depends on the alloy composition. α-Ti, the low temperature hexagonal phase transforms to bcc β-Ti at 882°C in pure Ti. The transformation temperature is suppressed by β-stabilizing impurities such as Fe ie 4% Fe reduces the temperature to 400°C. This paper examines the hydride formation in iodide-Ti and 99% pure Ti.

Thin foils of iodide Ti (.1Sn-.05 Si-.04Fe-.01Cu) and 99% pure Ti(Fe,Mo,Cu,Al) were encapsulated in vacuum tubes, annealed for 2 hours at 800°C, and quenched in ice water. The titanium was then charged in an H2SO4.H2O solution with an applied voltage of +4.5V for one hour. The samples were encapsulated in vacuum tubes and aged for 3 or 4 hours at 200°C.
Applications of image processing techniques to the structural characterization of small metallic particles
Authors: Pérez R. , Pérez-Ramírez J.G.
Published: June 2020

Digital image processing techniques have become one of the main tools on image characterization in transmission electron microscopy. Applications of these techniques in the field of small metallic particles are widely known. The results presented in this communication explore some of the structural characteristics of decahedral gold particles. The work is based on HREM images of these type of particles obtained along five-fold axis.

Small gold particles have been prepared by evaporation onto a vacuum cleaved NaCl surface. Lattice resolution images and microdiffraction patterns from individual particles have been obtained. Some of the images have been digitized with a scanning microdensitometer and computer processed.

Fig. 1 shows a HREM image of a decahedral gold particle obtained under diffraction conditions close to a five-fold zone axis. This image has been digitized and a computed “microdiffraction” pattern has been obtained from each of the five segments.
Low temperature transformations and twinning in La2-xSrxCuO4-δ and La2CuO4
Authors: Roy T. , Mitchell T. E.
Published: June 2020

Electron microscopists have played an important role in structure and microstructure determinations of ceramic superconductors ever since their discovery. Most of the work has been done on the 123 compounds. In the present investigation, we have used conventional TEM techniques at various temperatures to study the tetragonal to orthorhombic transformation in 214 compounds.

Single crystal La2CuO4 and polycrystalline La2-xSrxCuO4-δ (x∼0.15) were used in this investigation. La2CuO4 crystals were grown from a PbO flux and polycrystalline La2-xSrxCuO4-δ was made from stoichiometric mixtures of La2O3, CuO and SrO in the usual way. The results reported here were obtained from bulk ion-milled samples. Microscopy was performed using a Philips EM400T operating at 120kV, sometimes using a Gatan specimen cooler.

Both compounds have a triple perovskite structure. At room temperature, La2-xSrxCuO4-δ has a tetragonal unit cell (ao=3.775 A, co=13.223 A) while La2CuO4 has an orthorhombic unit cell (ao=5.363 A, bo=5.403 A, co=13.17 A).
Practical TEM cross section technique for ceramic superconducting thin films
Authors: Nazar L. R.
Published: June 2020

Within the last eighteen months, great interest has developed in certain ceramic materials which superconduct above liquid nitrogen temperatures. Recently it has been shown that these materials can be deposited as thin films on various substrates without significant change in critical temperature. Cross-sectional TEM studies have provided key information regarding the structure of these films and their interaction with the various substrates. However, specimen preparation for such studies can be difficult, and only a few successful results have been reported. This paper describes a successful method adapted from routine semiconductor cross section technique.

The following technique has been applied to specimens of superconducting ceramic films (Y-Ba-Cu-O) deposited by pulsed excimer laser or electron beam co-evaporation on sapphire and strontium titanate substrates.

Wafers bearing the films must have their major crystallographic axes identified and marked on the back surface. The wafer is cemented face down to a microscope slide with Crystalbond.
In Situ Annealing Observations of Silicon Cross-Sectional TEM Specimens
Authors: Fiore E.M. , Herring R.A.
Published: June 2020

With conventional transmission electron microscopy (TEM), dynamic events are pieced together with micrographs from a multitude of specimens annealed at different temperatures over the range of interest. Real-time imaging of dynamic events in the microscope provides the ability to view the entire anneal temperature span with one specimen. As reported by Parker, cross-sectional TEM can be used to observe real-time kinetic phenomena in silicon. Fiore and Herring later reported a new technique for preparing cross-sectional specimens that are annealable to temperatures as high as 1300°C. Both of these recently developed techniques have been used to observe the amorphous-to-crystalline phase transformation and defect network formation in high-energy ion implanted silicon.

Cross-sectional specimens were annealed in a Philips CM 12 transmission electron microscope equipped with a heating holder. The specimens were prepared from [111 ]-oriented silicon wafers implanted with 5.5 Mev Ga ions at a dose of lO15 cm-2. Using a ramp-up temperature from ∽30°C to 1000°C over a 5-minute period, the dynamic events were recorded on 3/4-inch video tape from a TEM TV system.
D-spacing/formula index for compound identification using electron diffraction data
Authors: Mighell A. D. , Himes V. L. , Anderson R. , Carr M. J.
Published: June 2020

NBS CRYSTAL DATA and the PDF-2 are large databases containing chemical, crystallographic and physical data on all classes of materials. From these databases, a derivative database has been prepared that is specifically designed for electron diffractionists. This database contains up to 60 calculated d-spacings for each of 70,000 inorganic compounds. An efficient computer program permits the identification of compounds by matching chemical and d-spacing data obtained from the unknown against the entire database.

A Printed D-SPACING/FORMULA INDEX has been prepared that contains a critical subset of the chemical and crystallographic data contained in the electron diffraction computer database. This printed index is designed to be used independently or in conjunction with the computer database. The INDEX contains one line of data for each of approximately 70,000 inorganic compounds. Each line contains a number of data items including: element types present; the first ten low-angle d-spacings; chemical formula; mineral name; lattice type; chemical class indicator; and unique CD and PDF numbers.
Copper precipitate formation by internal reduction of (Ni,Cu)O
Authors: Shao Beiling , Merkle K. L. , Reddy J. F. , Wiley C. L.
Published: June 2020

Studies of the structure and properties of metal-ceramic interfaces have recently become of considerable interest due to the need for a basic understanding of ceramic-metal bonds, which are increasingly used in ceramic technology. A convenient means to experimentally study such interfaces is by internal oxidation of metal alloys or by the internal reduction of oxide systems. In this manner low-energy interface structures are expected to be formed which provides a means for testing theoretical concepts regarding the energetics and structure of heterophase interfaces.

NiO-10at% Cu-doped polycrystalline boules were grown by the Verneuil process in an arc-image furnace. The reagent-grade starting powder from which the boule was grown was produced by the amorphous citrate process. The polycrystalline boule was cut into slices which were annealed separately at 900, 950, 1000, 1100, 1300 and 1500°C under CO2/CO atmospheres for 3 to 6 days.
Gallium ZSM-5 type zeolites: A catalytical and structural electron microscopy study
Authors: Acosta Dwight R. , Schifter Isaac , Contreras José L.
Published: June 2020

Synthesis of stereo selective zeolites using Gallium as partial or total substitute instead of aluminum, may lead to obtention of a novel class of zeo lites with modification of channel apertures, cage size and total acidity. Reaction velocity and selectivity for isomerization and cracking processes, for instance, are influenced by acid force of protonic sites, which may be selective or active for particular catalytic reactions.

Zeolites Z-683 and Z-691 with a 50% and 100% of A1 atoms substituted respectively, were synthesized using a modified method for ZSM-5 zeolite crystallization as described in the literature. The samples obtained were studied using ammonia (NH3) thermodesorption techniques. X-ray diffraction, high resolution electron microscopy, selected area electron diffraction and optical diffractometry methods were used in order to determine structural characteristics of zeolites above mentioned.

Figure 1 shows the results of NH3 thermodesortion studies for three zeolites: Z-601 (ZSM-5), Z-683 (50% A1 - 50% Ga) and Z-691 (100% Ga).
The release of asbestos fibers from vinyl-asbestos floor tiles
Authors: MacDonald H.S. , Kushnaryov V. M. , Kolinski S. , Gallun M.
Published: June 2020

There have been extensive studies of the release of asbestos fibers from friable materials used for construction. To date very little is known about the release of asbestos fibers from materials we assume to be non-friable. Since one of the major uses of asbestos was in the manufacture of floor tiles, and flooring is scoured prior to applying sealants, we have studied the release of asbestos from tiles treated in ways which model the processes tiles would be subjected to over their time of use.

Vinyl-asbestos tiles were gathered and assayed for their asbestos content by TEM and polarized light microscopy (PLM). Containments were set up and the following experiments performed: 1. 9 inch square tiles were drilled 10 times with a 3/4 inch drill 2. tiles were drilled once with the drill bit above 3. tiles were boken into 1 1/2 inch pieces 4. tiles were broken into 4 pieces 5. tiles were stripped, and then coated with sealants prior to further scrubbing.
On-line high resolution image analysis
Authors: Huang F. , Zhang J. P. , Buckett M. I. , Marks L. D.
Published: June 2020

A persistent practical problem in high resolution electron microscopy has been the diffulty to obtain careful, statistical comparisons between experimental and theoretical images. As a rule, practical applications of image simulation have involved either a direct comparison of calculated and experimental images, or a comparison of digitized images from a microdensitometer. Both of these pose substantial impediments to the final goal of HREM, namely R-factor measurements of the agreement between experimental and theoretical images.

As a step beyond these approaches, we have recently finished bus-interfacing a framestore device to an Apollo 3000 workstation. The full set-up is shown in Figure 1. The framestore device, an IMAGING 151 set of boards, can perform all the standard video rate processes such as recursive filtering, as well as accumulating a 16 bit image. This device is fully integrated into the Apollo mini-computer, and is set up so that images can be directly transferred to disk within the SEMPER software system.
An emerging technology: Nuclear magnetic resonance microscopy
Authors: Hennessy M.J. , Kwok E.
Published: June 2020

Much progress in nuclear magnetic resonance microscope has been made in the last few years as a result of improved instrumentation and techniques being made available through basic research in magnetic resonance imaging (MRI) technologies for medicine. Nuclear magnetic resonance (NMR) was first observed in the hydrogen nucleus in water by Bloch, Purcell and Pound over 40 years ago. Today, in medicine, virtually all commercial MRI scans are made of water bound in tissue. This is also true for NMR microscopy, which has focussed mainly on biological applications. The reason water is the favored molecule for NMR is because water is,the most abundant molecule in biology. It is also the most NMR sensitive having the largest nuclear magnetic moment and having reasonable room temperature relaxation times (from 10 ms to 3 sec). The contrast seen in magnetic resonance images is due mostly to distribution of water relaxation times in sample which are extremely sensitive to the local environment.
Boersch's electron optical bench updated
Authors: Geiger J. , Schmoranzer H. , Jakobs H. , Katterwe H. , Schröder B.
Published: June 2020

The electron optical module system designed by Boersch /l/ has proved a success in various laboratories. The system offers in principle the advantage of being highly versatile and flexible, and is applicable to perform various experiments involving electron optics by assembling standard types of modules.

The original electron optical bench does no longer meet the requirements of modern experiments. Therefore we have maintained on one hand the concept of simplicity and fast handling, e.g. in braking the vacuum and modifying the set-up. On the other hand we have improved the design in order to fullfill the following specifications:

In order to avoid contamination at surfaces which are exposed to electron bombardment the vacuum was improved up to 10-7 Torr. This was achieved by tolerating viton O-rings for static sealings only. Dynamic feedthroughs such as rotary or linear motion drives are sealed by stainless steel bellows. The diffusion pump uses silicon-free oil and is equipped with a machine cooled trap.
An improved magnetic prism design for a transmission electron microscope energy filter
Authors: Andrew John W. , Ottensmeyer F.P. , Martell E.
Published: June 2020

Energy selecting electron microscopes of the Castaing-Henry prism-mirror-prism design suffer from a loss of image and energy resolution with increasing field of view. These effects can be qualitatively understood by examining the focusing properties of the prism shown in Fig. 1. A cone of electrons emerges from the entrance lens crossover A and impinges on the planar face of the prism. The task of the prism is to focus these electrons to a point B at a focal distance f2 from the side of the prism. Electrons traveling in the plane of the diagram (i.e., the symmetry plane of the prism) are focused toward point B due to the different path lengths of different electron trajectories in the triangularly shaped magnetic field. This is referred to as horizontal focusing; the better this focusing effect the better the energy resolution of the spectrometer. Electrons in a plane perpendicular to the diagram and containing the central ray of the incident cone are focused toward B by the curved fringe field of the prism.
Coadsorption of lanthanum and boron on tungsten by field emission and field ion microscope
Authors: Inoue T. , Nakada M. , Okuno K.
Published: June 2020

The electron bean which has the sectional diameter of angstrom order and the high brightness is necessary to obtain an ultrahigh resolution in the field of electron microscopy, electron spectroscopy and other electron beam technology, and the field emitter called tip is suitable for this purpose. We have already published that we can make small protrusions near (100) planes on the tungsten tip apex by field evaporation at about 600 K.

Concerning the treatment of the tip called remolding we reported with my coworker, august 1974 at the eighth international congress on electron microscopy in Canberra Australia. The LaB6 field emitter has recently received considerable attention as an electron beam source of higher brightness as well as longer life time than conventional tungsten field emitter. LaB6 cathode has been used as such a cathode because of high thermal stability and stable for poisoning gas. However, the surface state of this cathode at high temperatures during operation has been scarcely known, because there has not been effective method to analyse the surface materials or to observe the surface condition.
Computer analysis of electron gun characteristics by surface charge method
Authors: Uchikawa Y. , Ohye T. , Maruse S.
Published: June 2020

Computer analysis of an electromagnetic field is indispensable when we come into design problems of electron optical devices. The difference method has been commonly applied where the potential of meshed space is solved using the successive over-relaxation (SOR), but it is fairly unfavorable in the electron optical application, since the potential derivatives necessary for the ray tracing must be evaluated numerically, open boundaries involve ambiguity in specifying their prerequisite potential values, and a large size of computer memories must be provided for mesh points, most of which are to cover the off-axis region where no electron paths take place. These problems become more serious for the case of an electron gun where the cathode has a very sharp curvature at the tip compared with the other configuration. It is for this reason that theoretical investigations could hardly present a quantitatively consistent interpretation over fundamental characteristics of the gun except for some papers which utilize analytical potential functions contrived under several approximations for simplified geometry such as a sphere cathode and an infinitely thin Wehnelt electrode.
The development of a combined deformation/heating stage with acoustic emission rate measurement for scanning electron microscopy
Authors: Wetzig Klaus , Edelmann Johannes
Published: June 2020

A novel in situ deformation and heating stage was constructed for use in the scanning electron microscope JSM - S1 /1/. It possesses the following technical features:

— tension loading up to 100 kp during electron optical observation, either with a constant tension load or with different, constant feed velocities from 1.10-3mm/min to 0,2mm/min;

— sample heating from r.t. up to 800°C under loading and imaging conditions;

— electrical measuring of tension and elongation respectively and plotting of σ-ε - curves;

— selective exchange of the tension support to a bending strain support, also with electrical registration of bending and load;

— selective connection with piezoelectric ceramics for acoustic emission rate measurements under loading and imaging conditions.

Figure 1 gives a schematic section through the tensile stage. The sample 1 is fixed in two chucks 2;3, which can move symmetrically against each other by the guiding rods 4; 5.
In-situ electrical-resistivity measurements in the high-voltage electron microscope
Authors: King W. E.
Published: June 2020

A side-entry type, helium-temperature specimen stage that has the capability of in-situ electrical-resistivity measurements has been designed and developed for use in the AEI-EM7 1200-kV electron microscope at Argonne National Laboratory. The electrical-resistivity measurements complement the high-voltage electron microscope (HVEM) to yield a unique opportunity to investigate defect production in metals by electron irradiation over a wide range of defect concentrations.

A flow cryostat that uses helium gas as a coolant is employed to attain and maintain any specified temperature between 10 and 300 K. The helium gas coolant eliminates the vibrations that arise from boiling liquid helium and the temperature instabilities due to alternating heat-transfer mechanisms in the two-phase temperature regime (4.215 K). Figure 1 shows a schematic view of the liquid/gaseous helium transfer system. A liquid-gas mixture can be used for fast cooldown. The cold tip of the transfer tube is inserted coincident with the tilt axis of the specimen stage, and the end of the coolant flow tube is positioned without contact within the heat exchanger of the copper specimen block (Fig. 2).
New detector system for cathodoluminescence SEM
Authors: Roschger P. , Hörl E.M.
Published: June 2020

The basic idea leading to the construction of our new detector system has been the realisation of maximum efficiency in collecting and detecting of the photons emitted by the specimen. A maximum of efficiency is necessary in many investigations, especially in biological ones where one has to deal with extrem low light levels. In many cases electron beam damage causes a rapid decrease of the light intensity, especially at high magnifications. In these cases a high sensitivity of the detector system is also very important.

Fig. 1 shows the principle of the design of our new system, consisting essentially of two ellipsoidal mirrors in contrast to one ellipsoidal mirror in our previous system. The left hand focus (F2) of mirror 1 is identical with the right hand focus of mirror 2. In this way a large fraction of the light emitted by the specimen is again focused in the left hand focus (F3) of mirror 2.
A new technique for measuring the local nitrogen concentration in Gap by means of the scanning electron microscope
Authors: Golubev Yu.A. , Evstropov V.V. , Kalinin B.N. , Lejnin V.P. , Petrov V.I.
Published: June 2020

The nuclear reaction and optical absorption techniques have been developed to determine the absolute nitrogen doping concentration in GaP crystals/1/.In both cases the data measured are averaged over the doped layer and these methods do not permit to obtain the nitrogen doping profile across the layer.In this work the measurement of the nitrogen concentration in GaP LED structures is carried out with high spatial resolution by using the local cathodoluminescence (CL) data obtained in the scanning electron microscope (SEM).

The method is based on determining in CL spectra the degree of the A-line self-absorption by substitutional nitrogen in GaP crystal.lt has been shown recently /2/ that in the temperature range of 77°K - 130°K without self-absorption the peak intensities ratio of A-line and its phonon replication side bands A-LO and A-2L0 in luminescence spectra of GaP should correspond to 1,00 : 0,36 : 0,065.
Dislocation core studies using high resolution electron microscopy
Authors: Cockayne D.J.H. , Anstis G.R.
Published: June 2020

The interpretation of high resolution (0.5nm) image detail to study dislocation cores relies upon image calculations for its justification. The scattering equations used to calculate these images make use of various approximations, and their validity at this level of resolution has been in doubt. Because of this, a detailed study has been made of the various methods of image calculation, and the reliability of image interpretation for a number of experimental situations has been determined.

Images of dislocations of arbitrary resolution can be calculated by an extension of the approach considered by Howie and Basinski. Given an expansion of the potential V(r) = Σgvg(r) exp (2Πig.r) and wavefunctions

then, for a given incident wavefunction, the wavefunction ψ(r) = Σgϕg(r) exp (2Πig.r) is the unique solution to the form of Schroedinger's equation in which backscattering is neglected, irrespective of the extent of lattice distortion.