Electron Photomicrographs Research Articles

Key to the eggs of the equid stomach bot flies Gasterophilus Leach 1817 (Diptera: Gasterophilidae) utilizing scanning electron microscopy

Abstract. A key to the eggs of the equid stomach bot flies is presented. Scanning electron photomicrographs of eggs are used to illustrate differences among the eight Gasterophilus species. The eggs include those of G.haemorrhoidalis (Linnaeus, 1758), G.inermis (Brauer, 1858), G.intestinalis (De Geer, 1776), G.meridionalis (Piller and Evans, 1926), G.nasalis (Linnaeus, 1758), G.nigricornis (Loew, 1863), G.pecorum (Fabricius, 1794), and G.ternicinctus Gedoelst, 1912. The eggs of G.meridionalis and G.ternicinctus are shown for the first time. Egg profile is the same for a particular species and is used as a key character for egg identification. Colour of eggs is used in some couplets but only as a supplemental character. Absence or presence of striae on the eggs is used as a primary contrasting character to separate G.pecorum from the other seven species. Shape of the striae varies on eggs of the same species, even those dissected from the same specimen, and is therefore deemed an unreliable taxonomic character for further separation of the Gasterophilus species. Eggs of the same species taken from specimens throughout the world appear the same in profile. Two sets of eggs require close inspection for adequate identification: G.inermis and G.nigricornis separated primarily by the shape of the microphylar region; and G.intestinalis and G.ternicinctus separated by the shape of the egg ventrum. All other eggs have very unique and distinctive profiles. Only G.pecorum was found to possess the Type‐II egg attachment organ (AO) used for adherence of the egg to plants or flat surfaces. The eggs of the remaining seven species possess a Type‐I AO used to attach the eggs to hair shafts. The type of AO and the degree that the Type‐I AO is extended posteriorly were used as key characters in the first and second couplet respectively.

A study of characterize indoor particles in three non-smoking homes

Aerosol concentrations and particle size distributions in three middle income homes were characterized over a three day period. Occupants of the homes were non-smokers. A single central sampling location between the kitchen and dining room areas was used in each of the homes. Thirty-seven and 47 mm prototype personal sampling inlets were collocated with two fixed PM 10 dichotomous ambient samplers to determine the average concentration of particulate mass during daytime and evening-early morning sampling periods. Particulate concentrations in the three homes ranged from 14 to 42 μg m −3. On average, 37% of the particle mass was collected in a fine (2.5 μm aerodynamic diameter or below) fraction, 26% was observed in a coarse fraction between 2.5 and 10 μm, and 37% was found in a fraction greater than 10 μm. Particle concentrations obtained with prototype personal samplers compared reasonably well to those obtained with 10 μm ambient air dichotomous samplers. Aerosol size information obtained from automated aerosol instruments suggests that the most significant event for generating small particles in all of the households was cooking. Household vacuum sweeping was the most significant large particle generating event. Electron photomicrographs indicated that particles below 1 μm dominate the particle size-number distribution. Biological and mineral based particles predominantly make up the 2.5–10 μm size range.

A REVISION OF THE GENERA MYCETOPORUS MANNERHEIM AND ISCHNOSOMA STEPHENS (COLEOPTERA: STAPHYLINIDAE: TACHYPORINAE) OF NORTH AND CENTRAL AMERICA

AbstractThe North and Central American species formerly placed in the genus Mycetoporus are revised. Two genera are recognized, Mycetoporus Mannerheim and Ischnosoma Stephens, each with 18 species. The morphological and historical basis for this division is discussed. Ten species of Mycetoporus are described as new: bipunctatu, floridensis, impunctatus, neomexicanus, nidicola, pacificus, rufohumeralis, segregatus, smetanai, and triangulatus. Ten species of Ischnosoma are described as new: arizonense, ashei, costale, durangoense, fimbriatum, hermani, lecontei, mexicanum, pecki, and suteri. Mycetoporus boreelus J. Sahlberg, a species restricted to the Palearctic region, is removed from synonymy with M. nigrans Mäklin and Mycetoporus insignis Mäklin is found to be a junior synonym of M. americanus Erichson. Mycetoporus discalis, M. punctatissimus, and M. punctulatus, all species described by Hatch (1957), are transferred to the genus Bryoporus subgenus Bryophacis and the name Tachinus humidus Say is treated as a nomen dubium in the genus Mycetoporus.The usage of the generic names Mycetoporus Mannerheim and Ischnosoma Stephens is discussed. The North American species of the genus Mycetoporus are placed in six species groups and those of the genus Ischnosoma are placed in four species groups.A neotype is designated for Mycetoporus nigrans Mäklin and lectotypes are designated for M. americanus Erichson, M. insignis Mäklin, M. tenuis Horn, M. lucidulus LeConte, M. consors LeConte, Ischnosoma pictum (Horn) and I. flavicolle (LeConte). The following species were transferred from Mycetoporus to Ischnosoma and are new combinations: pictum Horn, splendidum Gravenhorst, flavicolle LeConte, virginiense Bernhauer, coxale Sharp, hospitale Fall, californicum Bernhauer and Schubert, and curtipenne Bernhauer.All genera, species groups, and species are described and the species are illustrated with line drawings and scanning electron photomicrographs. Keys are provided to distinguish the genera Mycetoporus and Ischnosoma and for all the species in each genus. The New World distribution of each species is mapped. The biology of each species, if known, is discussed.

Saccharide composition of extracellular polymers produced by soil microorganisms

Microorganisms vary widely in their ability to produce extracellular polymers (ECPs). The saccharide composition of ECPs (water-soluble and water-insoluble fractions) obtained from three soil Pseudomonas strains was compared to the saccharide composition of ECPs of Arthrobacter viscosus. Azotobacter indicus. Bacillus sublilus, Chromobacterium violaceum, Cryptococcus laurentii, Hansenula holstii and Mucor rouxii. The saccharide composition of the ECPs ranged from two homopolysaccharides ( B. subtilus: H. holstii) composed of 770 and 930 mg saccharides g −1 ECP organic C, respectively, to heteropolysaccharides ( Pseudomonas strains) consisting of < 30 mg saccharides g −1 ECP organic C. The saccharide composition of the water-insoluble ECPs obtained from the Pseudomonas strains was independent of the saccharides added to the growth medium as a C and energy source. Glycoproteins were the major constituents of the water-insoluble Pseudomonas ECPs ranging from 315 to 510mg protein g −1 ECP. Those ECPs contained active fractions of acid and alkaline phosphatase. invertase. urease and β-glucosidase. Electron photomicrographs revealed massive excretion of ECPs possibly functioning in colonization and protection of exoenzymes.

Reduction of endothelial microfilament bundles in the low-shear region of the canine aorta. Association with intimal plaque formation in hypercholesterolemia.

To interrelate in vivo wall shear stress, endothelial microfilament bundle formation, and atherosclerosis localization, we used a mild abdominal aortic stenosis in 11 beagles to produce a range of wall shear stresses above and below the constriction. Six of the beagles were fed standard animal chow supplemented with 5% cholesterol and 10% coconut oil. Wall shear stresses, endothelial microfilament bundles, and intimal plaque localization were assessed along the stenosed aorta. Shear stress was determined in vivo from the near-wall velocity profiles with a 20-MHz, 80-channel, multigate Doppler velocimeter. Content of the microfilament bundles was quantified by planimetry of transmission electron photomicrographs. After 6 weeks, mean shear stress was higher immediately upstream from the throat of the stenosis than at the proximal site (46.1 +/- 7.3 dynes/cm2 versus 24.0 +/- 6.2 dynes/mc2, p less than 0.001) and was significantly lower immediately distal to the stenosis than at the proximal site (9.4 +/- 0.3 dynes/cm2, p less than 0.01). The microfilament bundle content increased immediately upstream from the throat of the stenosis and decreased immediately distal to the stenosis compared with the proximal site in both normocholesterolemic and hypercholesterolemic fat-fed beagles. Intimal plaques formed exclusively immediately distal to the stenosis in the hypercholesterolemic beagles. These findings suggest that a low shear-stress environment attenuates endothelial microfilament bundle formation, thus leading to a predilection for the initiation of atherosclerosis in atherogenic conditions such as hypercholesterolemia.

The Physico-Chemical Effect of Coacervation Conditions on the Diffusional Properties and Surface Morphology of Biodegradable Microcapsules

AbstractMicrocapsules containing kaolin and hydrocortisone 21- acetate (HCAC) were produced through controlled coacervation of a biodegradable block copolymer of d-tartaric acid and 1, 10-octanediol, under Plait and non-Plait compositions. Diffusional studies indicated that the permeability of Plait microcapsules was at least 40% greater than non-Plait microcapsules at the same polymer to core ratio. Scanning electron photomicrographs of the various microcapsules suggested surface morphologic differences among microcapsules produced under Plait and non-Plait solvent conditions.

Graphite formation in the Hiroshima fire storm

In order to investigate what might be the composition and optical properties of particles that could lead to a “nuclear winter,” a search has been made for particles that had been generated in urban fire storms. Deposits containing small amounts of graphite have been found on an artifact from the Hiroshima fire storm. The fire storm was initiated on August 6, 1945, by the atomic bomb detonation. The particles were rained out of the atmosphere in the “black rain” that commenced following the urban fire storm. Initial studies using electron microscopy have revealed that the particles consist of a mixture of clay and amorphous sooty carbon. Scanning electron photomicrographs have suggested the presence of graphite. Its presence has been confirmed using laser Raman spectroscopy (LRS), surface ionization mass spectroscopy (SIMS), and electron scattering for chemical analysis (ESCA). Significant amounts of the sooty material consists of clay, and the graphite is probably present as short-range ordered structure in sooty microspheres. The results of this study are presented with a discussion of conditions that may lead to graphite formation.

Coma chronique compliquant une maladie de Whipple avec biopsies du grêle et biopsie cérébrale négatives

A 57 year-old man was admitted to the hospital because of diarrhea and fever, followed by progressive mental disturbances and coma. Several jejunal and one cerebral biopsies as well as CSF studies failed to disclose any PAS-positive macrophages (PPM). Despite antibiotherapy, death occurred 13 months later. Neuropathological study demonstrated, throughout the CNS, multiple small foci of very dense gemistocytic gliosis with collections of scattered or perivascular PPM. The bacilli known in Whipple's disease were seen on electron photomicrographs.

Moisture Adsorption-desorption Effect on the Structure of Inclusion Complex of 6-Chloro-2-pyridylmethyl Nitrate and β-Cyclodextrin

A new anti-anginal drug, 6-chloro-2-pyridylmethyl nitrate (FR46171), was found to form a complex with beta-cyclodextrin (beta-CyD), molecular ratio 1:1. The FR46171/beta-CyD complex thus prepared showed a moisture adsorption-desorption hysteresis characteristic of hydrophilic polymers. The moisture adsorption-desorption isotherm and differential scanning calorimetry indicated that the moisture adsorbed FR46171/beta-CyD complex includes 13-15 mol of water while the moisture desorbed complex includes 5 mol of water. X-ray diffraction patterns of these samples confirmed their different structures. The scanning electron photomicrographs and the surface areas (BET) suggested that the moisture adsorption-desorption hysteresis observed in FR46171/beta-CyD complex can be attributed to reversible hydrogen bonding between water molecules and hydroxyl groups.

Inverse emulsions in a molten salt/hydroxy‐terminated polybutadiene system using block copolymers as emulsifiers

AbstractBlock copolymers of poly(N‐t‐butylbenzoyl ethylenimine) and poly(N‐propionyl ethylenimine) (Bx/Ey and Bx/Ey/Bx) or poly (N‐lauroyl ethylenimine) and poly (N‐propionyl ethylenimine) (Ux/Ey) were synthesized by cationic ring‐opening polymerization of 2‐substituted δ2‐oxazolines. Inverse emulsions (salt‐in‐oil) were made using these block copolymers as emulsifiers, hydroxy‐terminated polybutadiene (HTPB) as the nonpolar phase and methyl ammonium ethane sulfonate (MAES) as the polar phase. These inverse emulsions (S/O) were then cured using a triisocyanate to give a dispersion of molten salt (MAES) droplets in polyurethane. Pore sizes of these cured inverse emulsions were measured from scanning electron photomicrographs as a function of stirring time and concentrations of block copolymer and molten salt. The results indicate that pores with diameters in the range of 1.5 X 10−6 m can be obtained using triblock copolymer Bx/Ey/Bx, and that the surfactant molecules can be spread as a monolayer at the MAES‐HTPB interface.

Thermal Aging Properties of Graphite Fiber Reinforced Peek and Graphite Fiber Reinforced Bmi Composites

Abstract Graphite fiber reinforced poly(ether ether ketone) (PEEK) and graphite fiber reinforced bismaleimide (BMI) composite materials are two kinds of advanced fiber-reinforced polymer matrix composites with good thermal stability and excellent mechanical properties at high temperature. They are currently receiving considerable attention. the main limitation on their application is the lack of knowledge regarding their behaviors during extended use at high temperature. Thermal aging properties are the main parameters for new polymer matrix composites that will be used in advanced spacecraft structural components. From the results of thermal aging effects on the properties—including interlaminar shear strength, drop-weight impact strength, and impact energy—of graphite/PEEK and graphite/BMI composites, it is found that unidirectional graphite fiber reinforced composites retain higher strength compared to multidirectional, and that multidirectional graphite/PEEK composites keep higher property retentions than multidirectional graphite/BMI composites after thermal aging at 190°C. From scanning electron photomicrographs, it is also found that graphite/PEEK composites have better fiber/resin adhesion, intraply adhesion, and microcrack resistance compared to graphite/BMI composites after thermal aging.

Ultrasonic condensation of gutta-percha: An in vitro dye penetration and scanning electron microscopic study

Lateral condensation of gutta-percha with and without ultrasonic activation of the spreader was compared by use of dye penetration analysis and scanning electron photomicrographs of the gutta-percha fills in extracted human incisors and canines. The root canal fillings in three groups of 10 teeth each were laterally condensed using an ultrasonically activated spreader, a fine finger spreader, or a non-activated ultrasonic spreader. Significantly less apical dye penetration occurred when teeth were obturated using an ultrasonically activated spreader as compared with manual condensation with fine finger spreaders. The ultrasonically condensed gutta-percha mass was more homogeneous with fewer voids compared with gutta-percha masses from the two groups that were condensed without ultrasonic activation. A correlation between apical microleakage and the appearance of the gutta-percha mass was seen. All teeth with well-condensed, more homogeneous fillings had low dye penetration. All teeth with a high extent of dye penetration had poorly condensed, less homogeneous fillings. However, not all teeth that had poorly condensed fillings had high dye penetration.

Toughening of SAN copolymers by an SAN emulsion grafted rubber

A series of styrene/acrylonitrile (SAN) copolymers have been blended with an SAN grafted butadiene rubber to form ABS type materials. The major focus has been the effects of composition of the SAN matrix copolymer, for a fixed SAN graft, on blend toughness, deformation behaviour and morphology. The AN content varied from 0 to 40% in the matrix copolymers, while the AN content of the emulsion-made graft was fixed at 22.5%. Maximum strength and toughness were observed for compositions based on SAN matrices containing 34% AN. Mechanical dilatometry revealed no major changes in deformation mechanism as the AN content of the matrix changed. Most of the deformation was due to dilatational processes, presumably crazing. Transmission electron photomicrographs, on the other hand, showed differences in rubber particle dispersion. the morphology revealed by scanning electron microscopy of fracture surfaces distinguished the ductile and less ductile blends. Issues relating to the miscibility of the component polymers and adhesion are discussed.

Amination of ultra-high strength polyethylene using ammonia plasma

Plasma treatment of ultra-high strength polyethylene (UHSPE) fabric using ammonia gas to implant surface amine groups was investigated. The effects of three treatment times and three treatment powers were studied. After treatment, the wettability of UHSPE fabric was found to increase dramatically, becoming completely wettable at treatment times greater than 1 min. The primary amine concentration, as determined by dye ion-exchange experiments, was greatest at a treatment time of 5 min and a power of 50 W. Scanning electron photomicrographs showed no change in surface texture. The strength of single fibers extracted from the fabric decreased approximately 10% at some treatment conditions.

カルボキシメチル化及びメチル化によるＴＭＰの保水値とシート強度の挙動

The object of this paper is to examine the influence of the changes in water retention value (WRV) of Douglas fir TMP by post-chemical substitution on the sheet density and the sheet strength.TMP classified 42 wire mesh was modified by carboxyme-thylation and methylation to the various degree of substitution. Then, yeild, degree of substitution (DS) of the introduced groups, WRV, heat of wetting, crystallinity, sheet density and sheet strengths of each modified TMP were determined.The following results were obtained.1. Weight increase of TMP after carboxymethylation or methylation increased only a little and the rate of delignification during these reaction was relatively small.2. WRV and heat of wetting of carboxymethylated TMP (CM-TMP) increased with an increse in DS of carboxymethyl group, while methylated, TMP (M-TMP) gave the maxima of WRV and heat of wetting at 0.37 of DS of methoxyl group. WRV of CM-TMP showed the greater value than that of M-TMP.3. The crystallinity of CM-TMP and M-TMP fibers decreased with an increase in DS of carboxymethyl or methoxyl group. The decrease of crystallinity becomes more remarkable by carboxymethylation than by methylation.4. Density of CM-TMP handsheets increased with an increase in WRV, while the density of M-TMP handsheets showed a maxima at 0.82 of DS of methoxyl groups.5. An increase in TMP sheet density caused by the carboxymethylation and methylation results in the increase in tensile strength and burst factor of the handsheets. The both strengths of M-TMP showed a maximum at 0.37 of DS of methoxyl group. On the other hand, it was found that CM-TMP or M-TMP handsheets showed a maximum value with the tear factor.6. It can be seen from the scanning electron photomicrograph that the enhance in TMP flexibility and conformability followed by swelling with the process of carboxymethylation or methylation results in increase in the relative bonded area between the fibers in the handsheets.

Measurement of rubber particle fraction in high-impact polystyrene

The rubber particle fraction in high-impact polystyrene (HIPS) can be separated efficiently from the polystyrene matrix if the rubber phase is cross-linked using heat-treatment. A conventional gel test to measure the rubber particle weight fraction has been used on HIPS, which has been heat-treated to cross-link the rubber phase. The rubber particle fraction results obtained by the gel test method are shown to agree with results from an alternative method where the rubber particle fraction is calculated using measurements taken directly from transmission electron photomicrographs.

Fiber counts at multiple sites along the rat ventral root after neonatal peripheral neurectomy or dorsal rhizotomy.

We hypothesized that the afferent fibers in the ventral root of the rat are the third branches of dorsal root ganglion cells; these afferent processes in the ventral root are of varying length and end bluntly along the length of the root. In the case of an injury at either the central or the peripheral processes of the dorsal root ganglion cells in the neonatal stage, these fibers sprout at the blunt endings along the length of the ventral root. We cut either the sciatic nerve or the dorsal root on one side in neonatal rats. After the rats were fully grown, the number of both myelinated and unmyelinated fibers was counted in electron photomicrographs at multiple sites along the length of the ventral root. We observed a greatly increased number of unmyelinated fibers in the ventral root after the sciatic nerve had been cut at the neonatal stage. The magnitude of increase was more at the distal than at the proximal portion of the ventral root, suggesting that added fibers originated from the distal side. Neonatal dorsal rhizotomy, however, did not produce the same result. These results are consistent with our hypothesis that peripheral nerve injury at the neonatal stage triggers sprouting of the third branches of the dorsal root ganglion cells which end bluntly along the length of the ventral root in the normal animal.

Study of microporous membrane structure by image analysis

Quantitative image analysis is used to study the structure of microporous tubular hydrophobic PTFE membranes obtained by stretching. Structural differences are quantified by means of the surface porosity, the pore zone size and the pore zone number measured on scanning electron photomicrographs. These parameters depend upon the size of the membrane, its volumetric porosity and the equivalent pore diameter. Furthermore, the homogeneity of the membrane can be assessed by considering inner face, outer face and cross-sectional views of the membrane.

Artifacts of preparation in polymer microscopy

The interpretation of, and information available from a transmission electron photomicrograph, frequently depend upon specimen preparation. A major consideration in the selection of a preparation method is the potential for preparation artifacts. The goal of this work is to illustrate some sectioning and staining artifacts found in the preparation of a variety of polymer specimens. The following artifacts, in addition to several others, will be presented during the poster session.

Effects of Various Parameters on the Thickening of Softening Plant Sludges

Spectroscopic and thermal data for sludges from full‐scale softening plants showed calcium and magnesium precipitated as calcite and an amorphous hydrated hydroxide, respectively. Magnesium ions were not incorporated into the calcium lattice to form a magnesian calcite. Scanning electron photomicrographs indicated that only the calcium carbonate precipitate has a well‐defined crystal structure. The shift of the crystal size distribution (CSD) to greater sizes, observed by comparing the different sludges, may be due to bigger calcite crystals rather than to crystal size changes caused by the magnesium hydroxide. The settling rate of the sludges is related to the CSD. Higher fluxes were achieved with an upflow contact clarifier.