bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure of “Sensory” Surface Nerve Endings in Schistosoma Mansoni Miracidia
Authors: Jones Betty Ruth , Chi-Tung Pan Steve 
Published: June 2020

Schistosomiasis has been described as “one of the most devastating diseases of mankind, second only to malaria in its deleterious effects on the social and economic development of populations in many warm areas of the world.” The disease is worldwide and is probably spreading faster and becoming more intense than the overall research efforts designed to provide the basis for countering it. Moreover, there are indications that the development of water resources and the demands for increasing cultivation and food in developing countries may prevent adequate control of the disease, and thus, the number of infections are increasing.Our knowledge of the basic biology of the parasite causing the disease is far from adequate. Such knowledge is essential if we are to develop a rational approach to the effective control of human schistosomiasis. The miracidium is the first infective stage in the complex life cycle of schistosomes.
The Fine Surface Structure of the Male Genital Bulb of the Dwarf Spider Catabrithorax Plumosus
Authors: Cady C , Cyrus R. V. , Kaspar J. L. 
Published: June 2020

The spider Catabrithorax plumosus (Emerton) family Linyphiidae, subfamily Erigoninae is a member of an abundant yet reclusive group known as the dwarf spiders. Collectively, these are the smallest spiders in North America. Most measure only 1-3 mm in length, creating difficulties in indentification. The morphology of the male genital bulb, located on the distal pedipalp, is of great importance to the taxonomist in identifying spiders to the species level. This study examines the complex male genital structure in both the expanded and unexpended condition by means of the Scanning Electron Microscope (SEM).Pedipalps were removed at the trochanter-femur articulation, dehydrated in 70% ethanol and expanded by Immersion in lactic acid for 6-8 h. After complete expansion a graded amyl acetate series preceeded critical point drying. Unexpanded palps were dehydrated in an ethanol series followed by a graded amyl acetate series in ethanol. Specimens were critical point dried from CO2 and given an evaporated coating of carbon-gold. Specimens were examined in a Hitachi HHS-2R Scanning Electron Microscope operating at an accelerating voltage of 10 kV.
A study of geotropism in roots of pisum sativum through the use of transmission and light microscopy
Authors: Karas J. G. 
Published: June 2020

A current theory of graviperception in roots is the settling of starch grains in the columella tissue of the root cap. This settling against the endoplasmic reticulum or other cell components may induce calcium release along the lower cell membrane, which sets up an auxin sink; thereby allowing differential growth on that wall. In order to more thoroughly elucidate the role of starch grains (staloliths) in the graviperception mechanism knowledge of the structures and subcellular organelles found in the pea root tip in and adjacent to the region of graviperception in newly differentiated cells under conditions of gravitational change is needed. This presentation addresses some of these areas.Seeds of Pisum sativum - Dwarf Gray Sugar were surface sterilized in one percent sodium hypochlorite for twenty minutes followed by a twenty minute rinse in running tap water. The seeds were placed on two sheets of filter paper in one hundred mm plastic petri dishes containing five ml of free water. They were dark germinated for three days. One to one and one-half mm tips were harvested and dropped into solution A which contained twenty-five mis each of 8% Paraformaldehyde, 0.2 M cacodylate buffer adjusted to pH 7.6, and distilled water 1-1/2 hours at 4° C.
Effect of different colchicine concentrations on microtubules and membranes in tomato root tip cells
Authors: Jensen T.E. 
Published: June 2020

The effect of colchicine on microtubules has been investigated in numerous cell types. In this present study we have used different concentrations of colchicine to determine if the two major groups of microtubules in plant cells, plasma membrane associated and mitotic, are differentially sensitive to this drug.Tomato seeds “Michigan forcing” were germinated on filter paper saturated with distilled water. Radicles 1.5 to 2.0cm were selected and placed into either distilled water or colchicine, 0.001, 0.01, 0.03, 0.04, 0.05, 0.1%, for 20 hrs. During this time they were kept at 20°C in dim light. Root tips were fixed in 3% glutaraldehyde in phosphate buffer at pH7.2 for lh at 4°C. After 5 rinses in buffer they were placed in 1% OsO4 in phosphate buffer at pH7.2 for 1h at 4°C. Root tips were then dehydrated in ethanol, treated with propylene and embedded in Epon.No growth occurred in any of the colchicine treated radicles. Observation of thin sections of control cells revealed many plasma membrane associated microtubules, many cells in division stages and the usual arrangement of cell organelles.
Ultrastructure of feline calicivirus-infected crandell's feline kidney (CRFK) cells in culture
Authors: Dick C. P. , Johnson R.P. , Bast T. , Yamashiro S. 
Published: June 2020

Viruses frequently are difficult to visualize using routine transmission electron microscopy (TEM) of tissues collected from infected animals. Using cell cultures infected with viruses as in vitro models, viral replication and their resultant cytopathic effects can be more easily examined.Feline calicivirus (FCV), a common upper respiratory pathogen in cats has been successfully propagated in Crandell's Feline Kidney (CRFK) cells and a number of ultrastructural viral inclusions noted (1-4). This study represents further investigation of FCV infected CRFK cells using strain 255. The similarities and differences in our findings as compared to those of previous investigations have been explored.Confluent monolayers of CRFK cells in 80 cm2 plastic flasks were inoculated with 105 median cell culture infectious doses of FCV strain 255. When approximately 60 percent of cells exhibit FCV cytopathic effect the medium was decanted and the cells scraped from the surface using a rubber policeman. The cell suspension was centrifuged at 5000 rpm for 20 minutes at 4°C. Details of the procedure have been reported previously (5).
Ultrastructural morphology of the epidermis of the dog with generalized demodectic mange
Authors: Al-Bagdadi F. , Foil C. 
Published: June 2020

The canine skin is considered a normal environment for the Demodex mite (Scott et al, 1974). The parasite dwells in the hair follicles and sometimes the sebaceous glands of the skin (Muller et al, 1983) and occasionally inhabits the apocrine sweat glands (Scott, 1979). No mention of the mite nesting within the epidermis has been made. The life cycle of the mite and the eruption of the disease is an unresolved puzzle. The majority of the articles written on the subject deal with the treatment of the disease. No mention of the epidermal changes in infected dogs has been made. It is necessary to explore the ultrastuctural changes of the skin for the hope of a better understanding of the disease and the mites inhabitation of the epidermis which has not been documented nor mentioned in the literature.Three short haired dogs with canine generalized Demodectic mange (CGDM) have been studied at the School of Veterinary Medicine clinic at L.S.U. and were treated during 1981-1985.
Evaluation of blocking agents in protein A-gold immunocytochemistry
Authors: Komuves L. G. , King E. J. 
Published: June 2020

Various blocking agent solutions are used in protein A-gold immunocytochemistry to prevent or reduce nonspecific attachment of antibodies and/or protein A-gold particles to tissue sections. In our study of intracellular antigens present at low levels, the inadequacy of some commonly used blocking solutions became evident. We, therefore, compared several blocking solutions by exposing L929 cell cultures, at 4 °C, to a hapten-labeled lectin (dinitro-phenol-labeled wheat germ agglutinin, DNP-WGA) that binds specifically to the plasma membrane. We then used the protein A-gold method to locate the bound DNP-WGA. Since endocytosis had been prevented, gold particles not associated with the plasma membrane were regarded as nonspecific.The cells were incubated with DNP-WGA for 2 h at 4 °C, and were then fixed with 2% glutaraldehyde and 2% paraformaldehyde in 0.1 M cacodylate buffer, pH 7.2. Some samples were also postfixed with osmium tetroxide.
Computer-assisted morphometry of synaptic terminal density in the aging brain
Authors: Casey M. A. 
Published: June 2020

In studying the circuitry of a given region of the brain, some knowledge of the density of synaptic terminals is useful. Such data is especially valuable when studying the brain under pathological or experimental conditions. The methods outlined in this paper have been used to detect axosomatic synaptic terminal loss in the aging rat brain, but they would be applicable to other experimental paradigms.The methods in the present paper have been described elsewhere, and were recently used in our study of the lateral superior olivary nucleus (LSO), a well-characterized cell group in the rat superior olivary complex, and a key component of the rat lower auditory pathway. Virtually all synaptic terminals ending on the cell bodies of LSO principal cells originate in the medial nucleus of the trapezoid body (MTB), which undergoes a significant loss of neurons with age in rats. Thus, we wanted to determine whether loss of MTB cells resulted in a significant loss of axosomatic terminals in the LSO.
characterization of amorphization in Ni-Ti multilayers
Authors: Alexander K. B. , Walker F. J. , McKee R. A. , List F. A. 
Published: June 2020

The formation of amorphous alloys through the solid-state reaction of crystalline multilayers has recently been studied by several groups. In each of these studies, the multilayers were entirely amorphous when there were less than 4-10 planes in each layer. Layer thicknesses larger than this resulted in crystalline layers, presumably separated by an amorphous film approximately 4-10 layers thick. Our intent was to measure the thickness of the amorphous film in Ni-Ti multilayer specimens with a wavelength (thickness of Ni + Ti layers) of 20 nm, or approximately 40 planes per elemental layer. In situ Reflection High Energy Electron Diffraction (RHEED) was performed during the film deposition and transmission electron microscopy of cross-sectional specimens was used to examine the as-deposited films.Nickel and titanium layers were sequentially deposited onto a 50 nm amorphous Ni-Ti codeposit on an unheated (001) silicon substrate in the ORNL Molecular Beam Epitaxy (MBE) facility with a vacuum < 10-9 torr.
Precipitation in S-ion implanted Si
Authors: Herring R.A. 
Published: June 2020

Using ion implantation for doping semiconductor materials can provide solute concentrations far exceeding the dopant solubility limit. Subsequent annealing of the implanted material produces a high density of dislocation loops. Although the number of dislocations can be reduced by annealing at higher temperatures the material cannot retain the solute in solid solution.We have examined this dilemma by implanting Si with high-energy (6-MeV) S ions to concentrations of ∽ 1020 cm-3, and then heat treating the implanted Si by rapid thermal annealing (RTA) as part of a fabrication procedure for making extrinsic-Si detectors. The maximum solubility limit of S in Si is ∽ 3 x 1018 cm-3. At RTA temperatures < 1000°C faulted dislocation loops formed in the implanted region [1], Above 1000°C the dislocation loops unfaulted and coalesced to form a dislocation network and what appear to be small dislocation loops or small cluster-like structures with maximum diameters of < 100 Å (Fig. 1).
Elemental imaging of thin specimens with an energy filtering electron microscope (EFEM)
Authors: Bauer R. , Probst W. , W.I. Miller  
Published: June 2020

In conventional TEM (CTEM), image contrast is determined by scattering absorption contrast, diffraction contrast and phase contrast. Phase contrast is produced by the interference of unscattered electrons and elastically scattered electrons. Scattering absorption contrast and diffraction contrast are produced by angle selection of the scattered electrons using an objective aperture diaphragm for brightfield, darkfield and diffraction images.In an EFEM, with an integrated imaging electron energy-loss spectrometer, angle selection is used as in CTEM, but, additionally, it is possible to perform energy selection. This is done from the energy-loss spectrum obtained for the specimen area imaged. Energy selection permits the elimination of all inelastically scattered electrons to improve contrast for brightfield, darkfield and diffraction images. This technique also permits imaging of selected, e.g. e1ement-characteristic, ine1astica11y scattered electrons. Images obtained in this way display object- specific or e1ement-specific contrast and are termed electron or element-spectroscopic images (ESI).
Energy-filtered STEM imaging of thick biological sections
Authors: Colliex C. , Mory C. , Olins A. L. , Olins D. E. , Tencé M. 
Published: June 2020

Energy filtered imaging of thick biological specimens offers an excellent alternative to HVEM or IVEM. In order to explore the physical parameters which effect the energy loss spectra and the images formed by various energy loss windows we undertook a quantitative study using a dedicated STEM (VG-HB501) fitted with an energy loss spectrometer and interfaced with sophisticated data acquisition capability. Our mathematical analysis is useful in predicting the quality of bright field thick specimen images formed with energy filtered electrons.Our specimen was the salivary gland of Chironomus tentans which contains giant polytene chromosomes. Conventional preparative methods included fixation, epon embedding, and cutting 0.5 μm sections. Digital images were formed at plasomon (∼25 eV) multiples (n = 0 to 7). For each image the mean (I), maximum and minimum intensities and the standard deviation (σ) were determined.
Measurement of solute segregation to grain boundaries in the AEM: A review
Authors: Williams D. B. , Romig A. D. 
Published: June 2020

The segregation of solute or imparity elements to grain boundaries can occur by three well-defined processes. The first is Gibbsian segregation in which an element of minimal matrix solubility confines itself to a monolayer at the grain boundary. Classical examples include Bi in Cu and S or P in Fe. The second process involves the depletion of excess matrix solute by volume diffusion to the boundary. In the boundary, the solute atoms diffuse rapidly to precipitates, causing them to grow by the ‘collector-plate mechanism.’ Such grain boundary diffusion is thought to initiate “Diffusion-Induced Grain Boundary Migration,” (DIGM). This process has been proposed as the origin of eutectoid transformations or discontinuous grain boundary reactions. The third segregation process is non-equilibrium segregation which result in a solute build-up around the boundary because of solute-vacancy interactions.All of these segregation phenomena usually occur on a sub-micron scale and are often affected by the nature of the grain boundary (misorientation, defect structure, boundary plane).
Mechanical twinning and subgrain formation in ordered Ti50Ni47Fe3
Authors: Moberly W. J. 
Published: June 2020

TiNi is an intermetallic compound with the B2(CsCl) crystal structure. As temperature decreases, it undergoes a martensitic transformation from cubic B2 to monoclinic B19', the reversibility of which is responsible for shape memory properties. Ordered intermetallics generally have limited ductilty, however, >50% elongation of TiNi has been produced by either warm or cold working. Consequently, thermomechanical processing has resulted in improved mechanical properties. TEM is required to characterize the deformation mechanisms (mechanical twinning and slip) and resulting substructures.Substitution of 3%Fe for Ni into the binary TiNi alloy (Ti50Ni47Fe3) depresses the martensitic transformation, such that room temperature working does not stress induce the martensitic transformation. In order to improve the mechanical properties of this B2 intermetallic, fully annealed (875°C/2 hrs) bars have been cold swaged 10%,20%,30% and 40%, followed by different recovery annealing treatments. Additional samples have been warm swaged at 500°C. The structure is observed optically and by TEM, utilizing Philips' EM 400 twin and EM 430 super twin microscopes.
Progress in parallel-detection electron energy loss spectroscopy
Authors: Krivanek Ondrej L. 
Published: June 2020

Parallel-detection electron energy loss spectrometers improve the detection efficiency by several hundred times compared to the traditional serial-detection spectrometers, but they have their own set of difficulties, such as the limited dynamic range of solid state detectors, the possibility of stray reflections of the intense zero loss beam giving rise to spurious background, and channel-to-channel gain variation. Fortunately, none of these difficulties is turning out to be insoluble. Here we report on improvements of the Gatan 666 parallel detection electron spectrometer in the areas of increasing the dynamic range of the detector, and in eliminating stray reflections.The increase in the dynamic range of the detector was needed especially for low energy losses (high spectral intensities), which usually saturated the detector even at the minimum acquisition time of 12 msecs. Accordingly, we have developed an electron attenuator which uses a magnetic dipole to sweep the spectrum across the detector perpendicular to the dispersion direction (Fig. 1).
Structural control with ultrafine particles
Authors: Liu Jun , Sarikaya Mehmet , Aksay I. A. 
Published: June 2020

Interest has increased in using ultrafine particles for structural control at the nanometer scale in making materials with improved properties. This study illustrates the possibility of controlling the structural development of nanosized particle aggregates by using surfactants to monitor the surface characteristics of particles. Both conventional and high resolution TEM are used to characterize the morphology of packing and the interfacial structures of particles. Experiments are carried out using both gold and silica particles, and the microscopy is performed with a Philips EM 430T at 300 kV.Stable colloidal gold suspensions are produced by reducing gold chloride with sodium citrate at 100°C which produces gold particles that are approximately spherical with diameters of about 15 nm2. High resolution images reveal that they are not single crystals, but contain fine substructures, including low angle grain boundaries and twins (Figs. 1 and 2).
Microstructural development during heat treatment and deformation of an aluminum-silicon carbide composite
Authors: Mahon G. J. , Howe J. M. 
Published: June 2020

Aluminum-SiC reinforced composite alloys are currently being considered for structural applications in the aerospace industry as a result of their increased strength and stiffness and reduced density when compared with their monolithic counterparts. However, the main drawback of these materials is their lack of tensile ductility and a decrease in fracture toughness. By deforming Al-SiC composites under hydrostatic pressure the tensile ductility can be increased. This enables changes in microstructure to be investigated after a few percent strain, thus providing information about deformation mechanisms in this class of materials. Conventional TEM techniques have been applied to study microstructural development during both heat treatment and deformation.The material studied was AA2124 with 13vol.%SiC, commercially manufactured by ARCO Chemicals using a process of hot compaction and extrusion. The material was solutionized at 504°C for 4 h, quenched and aged at 177°C for 8 h.
HREM of carbon/metal and ceramic/metal interfaces in composite materials
Authors: Ishida Y. , Ichinose H. , Wang J. , Suga T. 
Published: June 2020

As examples of interfaces between crystals of different type of bonding, interfaces of carbon fibre reinforced metal matrix composite and ceramic/metal diffusion-bonded interface are examined. It is our fundamental interest to understand the nature of hetero-bonding. Various problems originate from the difference of the nature of bonding. A difference in the thermal expansion coefficient alone produces internal stress accumulation that can lead to the fracture of the interface during cooling of the specimen. Stress relief by plastic deformation of metal would operate if no reaction layer is present at the interface. Otherwise, the fracture of the brittle component would result after the fracture of the reaction product itself or the interface between the brittle non-metal components. High resolution electron microscopy of the interface structures should give information useful for the assessment of the mechanism.The first part is the observation of interface between carbon fibre and aluminium. Figure 1 shows the cross sectional view.
HREM studies of Al2O3 precipitates in Nb
Authors: Kuwabara M. , Spence J. C. H. , Rühle M. 
Published: June 2020

High resolution electron microscopy (HREM) studies are, in principle, capable of determining the atomic structure of defects, such as interfaces,in crystalline materials. A quantitative evaluation of the defect structure requires, however, that the examined specimen fulfills certain conditions, e.g. low-indexed zone axes of both materials adjacent to the interface must be parallel to each other and to the electron beam. Well defined geometrical characteristics exist between a metallic matrix and oxide precipitates formed by internal oxidation of a metallic alloy.Results will be reported on structure and defects at Nb/Al2O3 interfaces formed by internal oxidation of a Nb-2.9 at % Al alloy (oxidation conditions: 30 min. at 1820 K, po2 ∽6.10-5mbar). In addition, information on growth mechanisms of the Al2O3 precipitate can be extracted from the HREM studies. An extended paper of the research will be published separately.Most Al2O3 precipitates possess a plate-like shape with dimension of (200...600) x (200...600) x (10...40) nm3.
Structure and chemistry of diffusion-bonded metal/ceramic interfaces
Authors: Rühle Manfred 
Published: June 2020

The application of modern engineering materials often requires that two different materials be bonded. The resultant interfaces must typically sustain mechanical and/or electrical forces without failure. Consequently, interfaces exert an important and sometimes controlling, influence on performance in such applications as composites, electronic packaging systems, thin film technology and joining.During joining by a diffusion-bonding process, surfaces of the two materials are brought into contact by applying a small load and temperature. During the bonding and the subsequent cooling cycle chemical reactions may occur leading to chemical gradients or chemical reactions. The actual reaction and diffusion paths depend on the activities of the diff erent elements present near the interface.Bonds of bulk Nb/Al2O3 and Ni/Al2O3 were formed (for details of bonding conditions, see Elssner et al. ) and structure of the interface as well as chemical gradients near the interfaces were studied by TEM, HREM and SEM.