bluuebunny/crossref_metadata_2025 huggingface dataset:
Visualization of small displacement of atoms in crystals by the processing of atom resolution images
Authors: Hashimoto H.
Published: June 2020

Detection of small displacement of atoms was carried out using diffuse and irregular diffraction spots and Aberration Free Focus (AFF) imaging.

Fig. 1 (a) shows the position of atoms of a Ti-Mo alloy where white and black discs represent the position of atoms in β-phase and ω-phase respectively. Namely, the ω-phase is formed by the displacement of atoms in B and C positions.

Fig. 1 (b) is an electron diffraction pattern of an as-quenched alloy that contains 16 diffuse diffraction spots due to the displacement of atoms. The corresponding electron micrograph photographed with AFF condition is shown in (c). The images of displaced atoms are rather difficult to see. (d) is the processed image formed by using only diffuse spots in the Fourier Transform (FT) of (c). The bright spots correspond to the shaded displaced atom regions shown in (a) and not to the atom positions which are not displaced [1].

Charge Density Waves (CDW) occur as periodic modulations of conduction electrons and produce the periodic lattice distortions.
Cuticular sensilla in the chelate periopods of the red banded coral shrimp Stenopus hispidus
Authors: Trabanino Salvador , Baerwald R. J.
Published: June 2020

The knowledge of structure and function of crustacean cuticular receptors, especially chemoreceptors, is still scant at the present due to an emphasis on the study of arthropod cuticular sensilla from the Insecta. This report describes by TEM and SEM the structure of sensory pegs along the cutting edge of the chelate periopods of the red banded coral shrimp, Stenopus hispidus, a cleaner shrimp in coral reefs.

Stenopus hispidus were collected from the Florida Keys and maintained in marine aquaria. Autotomized chelate periopods for SEM study were fixed in 4% glutaraldehyde in Na-cacodylate buffer, pH = 7.4; sonicated; placed in ethanol; critical point dried; and coated with gold-palladium with a Hummer V sputter coater. The material was then examined in a JEOL 35C SEM. Autotomized chelate periopods within 24 hrs post-molt were fixed for TEM in Karnovsky's fixative in 0.1 M Na-cacodylate buffer, pH = 7.4; post fixed in 1.0% OsO4 in the same buffer; dehydrated through a graded series of ethanols; embedded in Epon-Araldite; and examined in a Philips 300 TEM.
Three-dimensional reconstructions applied to the study of taste buds
Authors: Kinnamon John C. , Young Stephen J.
Published: June 2020

The vertebrate taste bud is an ideal system for the neurobiologist to study. The taste bud is constantly changing, replacing all of its cells approximately every 14 days. As old cells are dying, new cells are entering the taste bud and forming synaptic connections with sensory nerve fibers. It is thought that synaptic remodeling occurs continually within the taste bud. In addition, the taste bud is a suitable structure for three-dimensional (3-D) reconstructions, being roughly 60 μm wide and 80-100 μm in length. Approximately 50-150 cells comprise a typical taste bud from the circumvallate papilla of the mouse. Many of these spindle-shaped cells have apical processes that extend to the taste pore at the apex of the bud. Microvillar projections from those apical processes extend into the external milieu. It is thought that sapid stimuli come into contact with the microvilli of the taste cells and elicit a response that is transmitted first to sensory nerve fibers within the taste bud, and then to the central nervous system, where the event is sensed as taste or gustation.
Structure and function of neural networks in the retina
Authors: Sterling Peter
Published: June 2020

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.
Analysis of 3-d molecular distribution with the digital imaging microscope
Authors: Carrington W.A. , Fay F.S. , Fogarty K.E. , Lifshitz L.
Published: June 2020

Advances in digital imaging microscopy and in the synthesis of fluorescent dyes allow the determination of 3D distribution of specific proteins, ions, GNA or DNA in single living cells. Effective use of this technology requires a combination of optical and computer hardware and software for image restoration, feature extraction and computer graphics.

The digital imaging microscope consists of a conventional epifluorescence microscope with computer controlled focus, excitation and emission wavelength and duration of excitation. Images are recorded with a cooled (-80°C) CCD. 3D images are obtained as a series of optical sections at .25 - .5 μm intervals.

A conventional microscope has substantial blurring along its optical axis. Out of focus contributions to a single optical section cause low contrast and flare; details are poorly resolved along the optical axis. We have developed new computer algorithms for reversing these distortions. These image restoration techniques and scanning confocal microscopes yield significantly better images; the results from the two are comparable.
Fluorescence ratio imaging of dynamic intracellular ionic signals
Authors: Tsien R. Y. , Minta A. , Poenie M. , Kao J.P.Y. , Harootunian A.
Published: June 2020

Recent technical advances now enable the continuous imaging of important ionic signals inside individual living cells with micron spatial resolution and subsecond time resolution. This methodology relies on the molecular engineering of indicator dyes whose fluorescence is strong and highly sensitive to ions such as Ca2+, H+, or Na+, or Mg2+. The Ca2+indicators, exemplified by fura-2 and indo-1, derive their high affinity (Kdnear 200 nM) and selectivity for Ca2+to a versatile tetracarboxylate binding site3modeled on and isosteric with the well known chelator EGTA. The most commonly used pH indicators are fluorescein dyes (such as BCECF) modified to adjust their pKa's and improve their retention inside cells. Na+indicators are crown ethers with cavity sizes chosen to select Na+over K+: Mg2+indicators use tricarboxylate binding sites truncated from those of the Ca2+chelators, resulting in a more compact arrangement of carboxylates to suit the smaller ion.
Development of instrumentation to measure rapid calcium transits in neonatal rat ventricular myocytes
Authors: Hagler H. K. , Morris A. C. , Buja L. M.
Published: June 2020

Changes in the intracellular calcium levels in cardiac myocytes are important in the regulation of normal cardiac function and have been implicated in contributing to irreversible cell injury with ischemia or hypoxia. Intracellular measurement of total calcium changes with subcellular resolution have become routine using rapid cryofixation, cryosectioning, cryotransfer and energy dispersive x-ray microanalysis in analytical electron microscopes. The x-ray microanalysis technique measures total calcium changes within subcellular compartments, but does not distinguish between the bound and free calcium. With the successful development of fluorescent calcium indicators which may be introduced into cells without significantly buffering the intracellular calcium levels, it has become possible to measure rapid calcium transients during contraction. The primary requirements in the development of a system to utilize the fluorescent calcium indicators were to resolve calcium transients in individual cells (since the response to perturbations such as hypoxia is heterogeneous) and develop a system which would be flexible enough to accommodate new indicators as they become available.
Scanned aperture light microscopy
Authors: Ellis Gordon W.
Published: June 2020

Scanned aperture microscopy is a new form of light microscopy which allows unprecedented latitude in spatial filtering and/or contrast enhancement without sacrifice in either depth discrimination or resolution. This method which utilizes synchronous scanning at the condenser entrance pupil and the objective exit pupil should not be confused with confocal scanning light microscopy which scans the object and image planes.

In operation a point source of illumination, conveniently supplied by a light fiber, is scanned over the desired portion of the condenser entrance pupil while a spatial frequency selective and/or phase altering mask is synchronously scanned over a corresponding portion of the objective exit pupil in register with the image of the source. At each point in the scan, the image is the coherently filtered result of illumination along a unique direction relative to the specimen. Each of these incremental images is added in to create a final image which has the selectivity of coherent filtering with the depth discrimination and low noise characteristic of large aperture incoherent illumination.
Differential polarization imaging of sickled cells
Authors: Maestre Marcos F.
Published: June 2020

Recently we have developed a form of polarization microscopy that forms images using optical properties that have previously been limited to macroscopic samples. This has given us a new window into the distribution of structure on a microscopic scale. We have coined the name differential polarization microscopy to identify the images obtained that are due to certain polarization dependent effects. Differential polarization microscopy has its origins in various spectroscopic techniques that have been used to study longer range structures in solution as well as solids. The differential scattering of circularly polarized light has been shown to be dependent on the long range chiral order, both theoretically and experimentally. The same theoretical approach was used to show that images due to differential scattering of circularly polarized light will give images dependent on chiral structures. With large helices (greater than the wavelength of light) the pitch and radius of the helix could be measured directly from these images.
Interactive laser cytometry: Non-invasive microscopic approaches for the measurement of dynamic processes in animal and plant cells and tissue
Authors: Schindler M.
Published: June 2020

All aspects of cellular metabolic, biosynthetic, and replicative activity depend on the movement of signaling messenger molecules, macromolecules, and organelles between cellular compartments. On another level, individual cellular activity is coordinated and synchronized in tissues by the movement of molecules through trans-membrane structures forming aqueous channels between contiguous cells. The types of movement found in the cell can be discussed in terms of: a) diffusion, b) flow, and c) energy driven transport. Diffusive processes can be 1-, 2-, or 3-dimensional. An example of each type of diffusion would be the movement of control proteins along DNA/RNA strands (1-D), the lateral transport of proteins in membranes (2-D), and the intercellular movement of molecules through gap junctions or piasmodesmata (3-D). Flow processes have been most frequently observed in the bulk movement of animal cell plasma membrane and cytoplasmic streaming in plants, while energy driven transport has been most vividly demonstrated for the intracellular transport of vesicles along microtubule tracks.
Cryo-SEM of particulate suspensions
Authors: Sheehan J. G. , Scriven L. E.
Published: June 2020

Advances in particulate coatings for paper products and high-density recording media require an understanding of orientation, clustering, and cluster aggregation of submicron particles suspended in high volume fractions in liquid. Particles for paper coatings are typically platelets; for magnetic coatings, acicular, tabular, or compact metal oxide or composite grains. One goal is to visualize the dynamic microstructures behind the rheological properties of these suspensions.

Fixation of liquid calls for cryo-techniques. Replication for TEM examination is difficult because clusters and cluster aggregates adhere to carbon support films in such a way as to interfere with imaging and even disrupt replicas. The best technique we have found is cryo-SEM with freeze-fracture and deep etching.

A procedure similar to that for freeze-fracture replication for TEM was used. For each sample, a small drop was flattened between two copper sheets (Balzers BU 012 056-T and BU 012 054-T).
Ultrastructural Investigation of Human Atrial Myxoma
Authors: Siew S. , Leistikow E.
Published: June 2020

Atrial myxomas are the most common cardiac tumor in the adult and they account for about one half of all primary tumors of the heart. The growth of the myxoma results in the formation of an intracavitary mass which encroaches upon the capacity of the chamber leading to impedance with both the inflow and outflow, with subsequent damming back of blood and diminution of cardiac output. In addition, myxomas often extend to the atrioventricular orifice and may interfere with valve function. The tumors are accessible to surgical resection, therefore, a correct clinical diagnosis may result in a complete cure.

Eight atrial myxomas were studied by means of transmission electron microscopy. Scanning electron microscopy was performed on one of these cases. Five of the patients were female and 3 were male. The age range was 40 - 77 years with an average age of 56.6. Five of the myxomas were from the left atrium and 3 from the right. All of the tumors had been attached to the atrial septum.
Nifedipine, A Promising Drug for Prevention of Heart Changes During Weightlessness
Authors: Philpott D.E. , Kato K. , Stevenson J. , Miguel J. , Sapp W.
Published: June 2020

NASA plans to have a space station operating in 1994 and is considering a 30 month Mars flight. These plans call for exposure to microgravity for longer periods of time than space travelers have endured to date. Vascular deconditioning is known to occur during space flight and during simulated weightlessness. The degree of deconditioning for these extended flights and the amount of possible reversibility is unknown. If a sudden demanding burden should be placed on the astronaut after prolonged deconditioning, there could be serious consequences. Exercise has been tried with limited success. What is needed is a counter measure to deconditioning. Calcium channel blockers are known to protect the heart during the recovery phase after heart attacks by regulating the calcium influx, thus protecting the cell and mitochondria from calcium overload. Sudden demands also increase blood flow, mimicking the post attack reperfusion, and could be serious for a deconditioned heart. We have found nifedipine, a calcium channel blocker, to be a promising drug for prevention of structural changes during simulated weightlessness.
Cytotoxic Effects of Diethylnitrosamine on Renal Tissue of Medaka Embryos
Authors: Norton W. N. , Gardner H. S.
Published: June 2020

The use of specific species of fish as bioassay systems for carcinogenicity studies is a relatively new approach to the investigation of cellular transformation. As a result, there are considerable voids in our basic knowledge of the biochemical, cytochemical and ultrastructural manifestations of exposure to selective carcinogens. The Japanese medaka, Oryzias latipes, has served as a popular fish model for carcinogenicity studies, many of which have included diethylnitrosamine (DENA), a site-specific carcinogen for hepatic neoplasms. The primary objective of this investigation was to obtain ultrastructural information on the cytotoxic effects of a carcinogen demonstrated at a location other than the normal site of cellular transformation.

Embryos of medaka were exposed to 3000 mg/L DENA for 48 hours, rinsed and held in clean water at 30°C. An additional group of embryos was maintained at 30°C in a tank of tap water and functioned as a control. At 50 weeks subsequent to the exposure, several fishes from each tank were removed, anaesthetized with tricaine methanesulfonate and the kidneys excised and processed for electron microscopy. Pronounced manifestations of cytotoxicity were evident in the epithelium of the proximal convoluted tubule.
Neural Degeneration in the Spiral Ganglia of C57BL/6 Mice
Authors: Cohen Glenn M. , Grasso Joseph S.
Published: June 2020

C57BL/6 mice, along with several other mouse genotypes, have served as models for human presbycusis (age-related hearing losses). C57BL/6 mice and their genetic substrain C57/bl6 show progressively severe hearing losses, starting as early as 30 days postnatally. The hearing losses result from sweeping sensory (hair cell) and neural degeneration that begins in the basal end and advances apically. For the initial study of the spiral ganglia C57BL/6 mice, our two objectives were to develop criteria for identifying the different degenerative stages and determine Whether the same degenerative stages repeat themselves in both young and old mice.

Female C57BL/6 mice of seven ages, ranging from 1 1/2 to 32 months, were examined. The ears were exposed to the fixative (3.5% glutaraldehyde [GA]) within cne min after sacrifice. The cochleae were decalcified in 5% EDTA in 3.5% GA, postfixed in 1% osmium tetroxide, and embedded in Araldite 502 epoxy. Semithin (1μ) sections were stained with toluidine blue or p-phenylenediamine; thin sections were stained with uranyl acetate and lead citrate.
Neutrophil Myeloperoxidase Destruction by Ultraviolet Irradiation
Authors: Hanker J. , Giammara B. , Strauss G.
Published: June 2020

Only a fraction of the UV radiation emitted by the sun reaches the earth; most of the UVB (290-320nm) is eliminated by stratospheric ozone. There is increasing concern, however, that man-made chemicals are damaging this ozone layer. Although the effects of UV on DNA or as a carcinogen are widely known, preleukemia and acute myeloid leukemia (AML) have only rarely been reported in psoriasis patients treated with 8-methoxypsoralen and UV (PUVA). It was therefore of interest to study the effects of UV on the myeloperoxidase (MP) activity of human neutrophils. The peroxidase activity of enriched leukocyte preparations on coverslips was shown cytochemically with a diaminobenzidine medium and cupric nitrate intensification.

Control samples (Figs. 1,4,5) of human bloods that were not specifically exposed to UV radiation or light except during routine handling were compared with samples which had been exposed in one of several different ways. One preparation (Fig. 2) was from a psoriasis patient who had received whole-body UVB phototherapy repeatedly.
Alpha Helices of TMV Visualized by Cryo-Electron Microscopy
Authors: Jeng T.-W. , Crowther R.A. , Stubbs G. , Chiu W.
Published: June 2020

Tobacco mosaic virus (TMV) is a helical particle, the structure of which has been determined by X-ray diffraction. We chose it as a test specimen to investigate whether cryo-electron microscopy and computer image processing could reveal internal structure at high resolution in a non-crystalline specimen.

Low dose images of TMV embedded in a thin layer of vitreous ice were recorded at 60,000 magnification in a JEOL100CX electron microscope equipped with a cold stacje at -148°C. The best images were selected for processing on the basis of their optical diffractograms. The defocus was determined from the image of the carbon film adjacent to the hole over which TMV particles were suspended. The defocus values of processed images ranged from 5000 to -10000 Å. The initial processing steps included masking out the selected segment of a particle, interpolating the image to make the axis of a selected particle segment parallel to the transform array, straightening the particle segment by a real space correlation and re-interpolation procedure. The computed structure factors from the straightened particle segment were corrected for the effects of defocus by applying a Wiener filter function.
Quantitative Diameter Measurements of Chromatin and TMV Fibers in the Freeze-Dried State
Authors: Athey B. D. , Stout A. L. , Smith M. F. , Langmore J. P.
Published: June 2020

Although there is general agreement that Inactive chromosome fibers consist of helically packed nucleosomes, the pattern of packing is still undetermined. Only one of the proposed models, the crossed-linker model, predicts a variable diameter dependent on the length of DNA between nucleosomes. Measurements of the fiber diameter of negatively-stained and frozen- hydrated- chromatin from Thyone sperm (87bp linker) and Necturus erythrocytes (48bp linker) have been previously reported from this laboratory. We now introduce a more reliable method of measuring the diameters of electron images of fibrous objects. The procedure uses a modified version of the computer program TOTAL, which takes a two-dimensional projection of the fiber density (represented by the micrograph itself) and projects it down the fiber axis onto one dimension. We illustrate this method using high contrast, in-focus STEM images of TMV and chromatin from Thyone and Necturus. The measured diameters are in quantitative agreement with the expected values for the crossed-linker model for chromatin structure
Conformational Transitions in Escherichia coli Ribosomal RNAs as Visualized by Dedicated STEM
Authors: Wall J.S. , Maridiyan V. , Tumminia S. , Hairifeld J. , Boublik M.
Published: June 2020

The high contrast in the dark-field mode of dedicated STEM, specimen deposition by the wet film technique and low radiation dose (1 e/Å2) at -160°C make it possible to obtain high resolution images of unstained freeze-dried macromolecules with minimal structural distortion. Since the image intensity is directly related to the local projected mass of the specimen it became feasible to determine the molecular mass and mass distribution within individual macromolecules and from these data to calculate the linear density (M/L) and the radii of gyration.2 This parameter (RQ), reflecting the three-dimensional structure of the macromolecular particles in solution, has been applied to monitor the conformational transitions in E. coli 16S and 23S ribosomal RNAs in solutions of various ionic strength.

In spite of the differences in mass (550 kD and 1050 kD, respectively), both 16S and 23S RNA appear equally sensitive to changes in buffer conditions. In deionized water or conditions of extremely low ionic strength both appear as filamentous structures (Fig. la and 2a, respectively) possessing a major backbone with protruding branches which are more frequent and more complex in 23S RNA (Fig. 2a).
New Developments in Thaw-Fixation
Authors: Haggis G.H.
Published: June 2020

Some years ago we introduced a thaw-fix technique for SEM viewing of internal cell structure1. In thisptechnique cells or tissues are frozen unfixed, fractured at -170 to -190°C and thawed into fixative at room temperature. In early work we infiltrated cells with glycerol or dimethylsulphoxide (to 25-30%) prior to freezing, to avoid ice crystal artifact during freezing and thawing. This infiltration took 20 mins, to 1 hr. with the possibility of ultrastuctural change during this time, since the cells were unfixed. Results for interphase chromatin were interesting but cytoplasmic structure was not well preserved. We have now improved our techniques for rapid freezing and rapid thawing and report results here for fresh material, rapidly frozen without cryoprotectant, showing excellent cytoplasmic preservation. Interphase chromatin shows structural detail comparable to that obtained earlier with glycerol cryoprotection.

3T3 cells were grown on 20μm fibrin films, rapidly frozen by propane-jet freezing, fractured in a Balzers BAF 400 freeze-etch unit at -170°C and thawed into a fixative of Bershadsky buffer3 + 1.5% glutaraldehyde.
Heavy Atom Clusters as Specific Labels
Authors: Hainfeid James F.
Published: June 2020

An important milestone in electron microscopy was the first visualization of single atoms in 1970 with the STEM designed by Albert Crewe. This achievement inspired thoughts that single heavy atoms could be used as super high resolution labels of biological structures by, for example, covalently reacting a heavy atom reagent at the active site of an enzyme. Further investigation of heavy atoms on thin carbon films revealed that they hopped about and that this was not solely thermal motion, but beam induced, since cooling the specimen had little effect. Attempts were made to try various heavy atom compounds but alas, these all behaved similarly, with about 10% of the atoms moving 3-10 Å on successive scans. A gallant effort by M. Beer to sequence DNA using heavy atom base specific labels befell similar problems where the motion of the label prevented high resolution coordinates from being measured.
Ultrastructural Evaluation of Ischemic Skeletal Muscle Reperfused with Oxygen Free Radical Scavengers
Authors: Mathur A. , Russell R.C. , Roth A.C. , Wagahoff D.
Published: June 2020

Skeletal muscle is very sensitive to ischemia. A prolonged preoperative ischemic interval decreases the chances for successful replantation of an amputated limb. Recent experimental work has implicated toxic oxygen free radicals produced during reperfusion of ischemic tissue to be responsible for some of the observed deleterious cellular changes. Selected oxygen free radical scavengers have been used to increase skeletal muscle survival following total ischemia. This study examined the effect of systemic administration of a superoxide free radical scavenger, superoxide dismutase (SOD), and a hydroxyl radical scavenger, dimethylsulfoxide (DMSO) just prior to reperfusion, on the ultrastructure and function of ischemic rabbit anterior tibialis muscle.

White male New Zealand rabbits were used for this study. The right hind limb of each rabbit was made ischemic by dissecting and clamping the femoral artery and vein proximal to the bifurcation of the profundus artery and vein. A penrose tourniquet was also placed around the knee. The animals were divided into groups subjected to either 5 or 8 hours of ischemia.
Confocal Laser Microscopy of Physiologically Characterized Fluorescently Labeled Central Nervous System Neurons
Authors: Turner J.N. , Swann J. , Smith K. , Siemens M. , Szarowski D. , Collins D.N.
Published: June 2020

Confocal laser scanning microscopy (CLSM) is capable of three-dimensional imaging of fluorescently labeled single cells. Efficient detection via a photomultiplier and optical sectioning with high rejection of light from other specimen levels make it possible to image cells surrounded by either labeled or unlabeled tissue. It is no longer necessary to restrict high resolution light microscopy to cultured cells or those near the surface of a tissue sample. Cells can be observed üin situ” in a physiologically characterized environment. Central nervous system neurons can be electrophysiologically characterized and then injected with a fluorescent dye such as lucifer yellow. The CLSM can excite the dye and image the fluorescent emission in thick tissue preparations (hundreds of micrometers) making possible a new approach to the correlation of physiology and anatomy.

Brain slices 350 μm thick were obtained from hippocampus and inferior colliculus of immature rats and incubated in oxygenated artificial cerebrospinal fluid. Cells were penetrated with micropipets, characterized electrophysiologically and ionophoretically injected with 5% lucifer yellow in LiAc.
An SEM/TEM study of structures associated with bacteroids in peanut (Arachis hyppogaea L.) root nodules
Authors: Emerson C. J. , Bal A. K.
Published: June 2020

Nitrogen-fixing peanut root nodules have highly specialized, large spherical bacteroids and show higher acetylene-reduction activity than the nodules of other legumes induced by the same strain of rhizobia. Differences are also found in their anatomical organization and with regard to bacteroid-associated organelles and other structures (dense bodies) found on the host-symbiont interface. In this investigation, further description of these organelles and structures was made at different stages of development in a correlated SEM/TEM study.

Arachis hypogaea L. cv. Jumbo Virginia plants were grown in environmental growth chambers and inoculated with Rhizobium sp. 32Hl. For TEM, slices of nodules were fixed in Karnovsky's fixative in Sorensen's phosphate buffer, pH 7.2 for 1 h at 4°C. Tissues were rinsed in buffer, post-fixed with 1% phosphate-buffered osmium tetroxide for 1 h at 4°C and dehydrated in ethanol. 1% p-phenylenediamine was added at the 70% ethanol step (30 min) to preserve lipids.
Structure of the surface of thornless blackberry fruits: Relevance to post harvest weight loss
Authors: Jones S. N. , Sapers G. M. , Douglas F. W. , Dobson Eastern T. O.
Published: June 2020

Strategies to improve marketability of small fruits include the identification of characteristics that contribute to longer shelf life. One characteristic of a durable berry is that it retains moisture after harvest and resists desiccation. In our study of 10 thornless blackberry cultivars and selections during refrigerated storage, weight loss varied from 1% to 3% per day and rates were linear for 10 days. Fluid leakage was not a factor, and the primary source of weight loss was concluded to be transpiration. Microscopy was performed to identify structural correlates of berry weight loss. Surface wax on plant structures is known to be a barrier to water loss.

Representative berries from the hand-selected fruits, sorted for weight loss analysis, were processed for microscopy 24-36 hr after harvest, during which time the fruits were held at 0-1 C. Samples were fixed with glutaraldehyde and osmium tetroxide, dehydrated with an acetone series, and embedded in Spurr's resin.
Maize Necrotic Lesion Virus Particles and Associated Cellular Inclusions
Authors: Bradfute O. E. , Louie Raymond
Published: June 2020

Maize necrotic lesion virus (MNLV), a newly found soil-borne virus, is apparently one of a complex of viruses infecting roots of maize (Zea mays L.) in northern Ohio (1). Maize roots become infected when plants are grown in infested, field soil that has undergone air-dry storage or in autoclaved, greenhouse soil infested with diseased roots. Symptoms on leaves of rub-inoculated maize and other monocot seedlings first appear as chlorotic local lesions that become necrotic after 24-36 hr.

Numerous isometric virus particles of two sizes, ca. 17 and 29 nm in diameter, were observed in crude extracts from MNLV lesions negatively stained in phosphotungstic acid, pH 4.8 (Fig. 1). At pH 6.9 the larger virus particles were frequently stain-penetrated and clumped together or embedded in an amorphous matrix (Fig. 2). MNLV-infected cells were also examined in thin sections cut from fixed and embedded chlorotic lesions (Fig. 3-4). In the cytoplasm of some mesophyll cells, numerous isometric virus particles of both sizes were clearly recognized in close proximity to each other and to masses of electron-dense, amorphous inclusions.
Alveolitis due to inhalation of acrylic polymers: Report of a case
Authors: Minda J. M. , Johns L. W. , Barrett T. E. , Mayock R. L. , Pietra G. G.
Published: June 2020

Acrylic polymers are increasingly used in dental laboratories for preparation of prostheses. In the past, dental technicians have developed pneumoconiosis due to inhalation of silica dust or heavy metal alloys, but to our knowledge, no other cases of lung disease due to inhalation of acrylic dust have been previously reported.

The patient, a dental student, was admitted to the Hospital of the University of Pennsylvania for evaluation of persistent bilateral interstitial infiltrates and cough. An open lung biopsy was performed to determine the cause of the infiltrate. The biopsy specimen revealed interstitial lymphocytic infiltrates and intra-alveolar accumulation of “foamy” macrophages (Fig. 1) suggesting lipoid pneumonia. Since he did not use medications containing mineral oil or had obstructive lesions of the airways, electron microscopy examination of the biopsy specimen was performed. Transmission electron microscopy (TEM) revealed accumulation of macrophages in the alveolar space and interstitium, containing numerous electron-lucent vacuoles of varying size (Fig. 2).
Ultrastructural comparison of prolactin adenomas of pituitary in men and women
Authors: Caughey R.C. , Kalyan-Raman U.P.
Published: June 2020

Prolactin producing pituitary adenomas are ultrastructurally characterized by secretory granules varying in size (150-300nm), abundance of endoplasmic reticulum, and misplaced exocytosis. They are also subclassified as sparsely or densely granulated according to the amount of granules present. The hormone levels in men and women vary, being higher in men; so also the symptoms vary between both sexes. In order to understand this variation, we studied 21 prolactin producing pituitary adenomas by transmission electron microscope. This was out of a total of 80 pituitary adenomas. There were 6 men and 15 women in this group of 21 prolactinomas.

All of the pituitary adenomas were fixed in 2.5% glutaraldehyde, rinsed in Millonig's phosphate buffer, and post fixed with 1% osmium tetroxide. They were then en bloc stained with 0.5% uranyl acetate, rinsed with Walpole's non-phosphate buffer, dehydrated with graded series of ethanols and embedded with Epon 812 epoxy resin.
Intracellular localization of hantan (HFRS) virus antigens by means of immune colloidal gold electron microscopy
Authors: Tao Hung , Semao Xia , Tungxing Chao , Zinyi Chou , Boquan Chen
Published: June 2020

Hantan (HFRS) virus, the etiologic agent of Hemorrhagic Fever with Renal Syndrome has been provisionally classified as a new genus of Bunyaviridae. We have described, in our previous papers, some distinctive morphogenetic features in HFRS virus infected cells namely, intracytoplasmic inclusion bodies (lb), virus associated granules, viral antigen layer(Val) etc, The actual roles of these structures, however, remain unknown and warrant further study. This paper reports the results of our study using immune colloidal gold electron microscopy.

Chinese HFRS isolates, A9 & R22, derived from Apodemus agrarius and Rattus nervegicus respectively were grown in Vero E-6 cells, harvested for EM 6-14 days of infection. The colloidal gold method was adapted from Tanaka with modifications. Both pre- and post-embedding were used and LK4M was used for the latter. Two monoclonal antibodies (McAb-100 & 102) against the virus glycoprotein I and II were donated by Dr. Yamanishi,5 and two group specific ones (McAb-A35 & A25-1), as well as two type specific (A20 to type I, R31 to type II HFRS virus) were domestic products.
Thiamine pyrophosphatase and nucleoside diphosphatase in guinea pig pinealocytes shown by a cerium-based method
Authors: Luo Z. R. , Whitter E. F. , Schultz R. L. , McMillan P. J.
Published: June 2020

Thiamine pyrophosphatase (TPPase) and nucleoside diphosphatase (NDPase) both have a similar localization in the endoplasmic reticulum (ER), the perinuclear space (PNS) and the Golgi apparatus (GA) in hepatocytes and other cell types. Whether they are two separate enzymes or a single one has not been determined. Recently cerium has been reported as an excellent substitute for lead. The study described here compared the activities of TPPase and NDPase in pinealocytes by the cerium-based method.

Guinea pig pineal glands were fixed by perfusion with a mixture of 1% glutaraldehyde and 2% paraformaldehyde followed by immersion in the same fixative for a total of 30 min. Sections cut at 100μm on a vibratome were incubated in substrate-free incubation medium for 30 min, then for 3 hrs at room temperature in the complete medium, which contained thiamine pyrophosphate (1 mg/ml) for TPPase and inosine diphosphate (1 mg/ml) for NDPase, cerium chloride (0.7 mg/ml), manganese chloride (1 mg/ml), and 5% sucrose in buffer.
Iron storage sites in the myocardium as revealed by cytohistochemistry
Authors: Ashraf M. , Thompson F. , Miki S. , Srivastava P.
Published: June 2020

Iron is believed to play an important role in the pathogenesis of ischemic injury. However, the sources of intracellular iron in myocytes are not yet defined. In this study we have attempted to localize iron at various cellular sites of the cardiac tissue with the ferrocyanide technique.

Rat hearts were excised under ether anesthesia. They were fixed with coronary perfusion with 3% buffered glutaraldehyde made in 0.1 M cacodylate buffer pH 7.3. Sections, 60 μm in thickness, were cut on a vibratome and were incubated in the medium containing 500 mg of potassium ferrocyanide in 49.5 ml H2O and 0.5 ml concentrated HC1 for 30 minutes at room temperature. Following rinses in the buffer, tissues were dehydrated in ethanol and embedded in Spurr medium.

The examination of thin sections revealed intense staining or reaction product in peroxisomes (Fig. 1).
A comparison of mass measurements with the stem using the wet-film technique with and without polylysine treatment
Authors: Simon M. N. , Shiue G. G. , Wall J. S. , Flory P. J.
Published: June 2020

The wet film technique of injection of a specimen into a drop on a thin carbon film (for eventual freeze-drying and mass analysis in the STEM) has been described and shown to give a uniform background and, in general, good biological preservation of specimens. However, an occasional specimen either does not absorb well or is of necessity very dilute. Many specimens absorb to polylysine-treated grids nearly 10-fold better than to thin C alone. We describe here our adaptation of the polylysine treatment originally described by Williams, and our finding that polylysine-treated thin C does not give significantly worse errors in mass measurements than thin C alone.

To prepare a specimen, thin C is floated off cleaved NaCl onto a dish of water. Grids covered with holey film are dropped onto the thin C. A grid is picked up, inverted and washed with water, buffer, specimen, buffer. For poly lysine grids, after washing with water, 5 μl of 10 μg/ml poly lysine is injected for 1 minute.
Low-cost digital-image processing and analysis system for on-line morphometric measurements of sem images
Authors: Rosenfeld Michael E.
Published: June 2020

The widespread use of digital image processing systems for high resolution morphometric applications has been limited by the cost and difficulty of interfacing systems to electron microscopes. The recent development of image acquisition boards and software for PC-AT based systems and the availability of scanning electron microscopes that are capable of scanning at true TV rates (RS-170 compatible signals), have alleviated these problems. We have assembled a system consisting of a Compaq Portable 286 (Compaq Computer Corp. Houston, TX) equipped with an FG-100 image acquisition board (Imaging Technology Inc. Woburn, MA), interfaced with a Philips 515 SEM containing a motorized stage and Edax stage controller (Philips Electronics Inc. Mahwah, NJ).

Utilizing commercially available software, this system has extensive image processing and morphometric analysis capabilities. For example, because TV scan rates generate images with low signal to noise ratios, improvement of the image quality is possible via real time image averaging and background subtraction using the the FG-100 board Feedback/Input lookup table.
Point-projection imaging of biological objects
Authors: Panitz J. A.
Published: June 2020

Point-projection microscopy is an attractive surface imaging modality. High magnification, resolution, and contrast are easily achieved by radially projecting charged particles from a specimen mounted several centimeters in front of an imaging detector within a vacuum environment. Stigmation, drift and alignment problems are negligible, or nonexistent. The trick is to generate charged particles at or near the surface of the specimen that must coincide with the surface of a smoothly curved, conducting electrode of radius R. A potential difference applied between this electrode and a counter electrode, coincident with the detector surface, accelerates the charged particles radially into space. When the charged particles reach the detector they will have magnified their point of origin at the specimen surface by ∼D/R, where D is the separation of the electrodes. For D ∼10 cm and R ∼100 nm, the magnification is ∼106. If the particles have a forward velocity much greater than their lateral velocity (and a small DeBroglie wavelength), a highly resolved image of the specimen surface will appear at the detector.
TEM diffraction investigations of amorphous materials
Authors: Pelton A. R.
Published: June 2020

Transmission electron microscopy has proven invaluable for studies of amorphous materials. The combination of imaging, diffraction and chemical analysis is particularily important for investigations of small volumes of mixed crystalline and amorphous alloys. Several articles have been published recently that describe imaging and EDS of metastable alloys [1-3]. The purpose of this paper is to outline the use of electron diffraction techniques to obtain both qualitative and quantitative structural information from non-crystalline materials.

The SADPs in Fig.1 were taken from a study of rapidly-solidified Ti-Zr-Be metallic glasses [4,5]. Initial investigations of these alloys reported apparent evidence from calorimetry and TEM for amorphous phase separation [4]. The images from that study were characteristic of crystalline alloys that undergo spinodal decomposition. However, more recent investigations of the same alloys were able to show conclusively that the “amorphous spinodal” microstructures were actually due to thin-foil artifacts [5].
Investigations of short range order in amorphous Fe-B alloys
Authors: Zweck J. , Hoffmann H.
Published: June 2020

Amorphous metallic alloys exhibit a large variety of physical properties that often differ from their crystalline counterparts of the same composition. Currently, metallic glasses exist which, to name only a few examples, are either very non-abrasive, soft magnetic and magneto optical, hard, flexible, or resistant to corrosion. These properties are of great technical importance and there are many applications that are based on amorphous alloys. Since physical properties are related to the structure of a material, a better knowledge of the ‘structure’ of the amorphous state is of great interest. In this work, we present pair distribution functions determined from electron diffraction results for amorphous Fe-B alloys of different compositions. From the pair distribution functions one can obtain information about near neighbor distances, the range of a short range order (SRO) for different compositions, and of similarities to crystalline counterparts. These findings will also be compared to results obtained with the use of high resolution electron microscopy (HREM).
The formation and recrystallization of amorphous zones produced in GaAS by ion irradiation
Authors: Bench M. W. , Robertson I. M. , Kirk M. A.
Published: June 2020

Transmission electron microscopy experiments have been performed to investigate the lattice damage created by heavy-ion bombardments in GaAs. These experiments were undertaken to provide additional insight into the mechanisms by which individual amorphous zones and eventually amorphous layers are created. To understand these mechanisms, the structure of the defects created as a function of material, irradiating ion, dose, dose rate, and implantation tenperature have been studied using TEM. Also, the recovery of the crystalline structure by annealing has been investigated.

These experiments were performed at the High-Voltage Electron Microscope - Ion Accelerator Facility at Argonne National Laboratory. This facility consists of an HVEM which has been interfaced with two ion accelerators. This coupling, plus the availability of several specimen stages permits ion irradiations to be performed in the specimen chamber of the microscope at controlled temperatures from 10 to 1000 K.
Evaluation of amorphous and crystalline SiC by extended energy loss fine structure (EXELFS) analysis
Authors: Angelini P. , Sklad P. S. , Sevely J. C. , Hssein D. K.
Published: June 2020

Crystalline as well as amorphous forms of silicon carbide are materials which have important uses in many areas of materials science including structural ceramics, coatings, and semiconductors. The characterization of SiC by the use of the EXELFS technique yields radial distribution functions (RDF) which are sensitive to the structure and composition within near neighbor distances of either C or Si atoms. In this way a quantitative analysis of possible variations in “structure” can be made. EXELFS analyses of crystalline SiC are especially important in order to evaluate the method when comparison with results from the amorphous state are to be made. The EXELFS technique has previously been applied to study both crystalline as well as amorphous materials.

Crystalline as well as amorphous SiC was evaluated. One specimen was a commercially available SiC single crystal. Two other specimens utilized a similar SiC starting material which had been made amorphous either by ion implantation with chromium or by irradiation from 300 kV electrons.
Ion beam stimulated reactions in metallic alloys
Authors: Mansur L. K. , Lee E. H.
Published: June 2020

Ion implantation, ion beam mixing, and ion beam stimulated reactions can be discussed as somewhat distinct but related processes. The first two emphasize compositional changes in near-surface regions. The last relies mainly on microstructural and precipitation reactions caused by atomic displacements. In this last area much of the work has been carried out in metallic alloys. Here we summarize experiments in our laboratory that cover several ion-beam-induced reactions in Fe-15Ni-15Cr base alloys, to provide a perspective on related work in materials other than silicon. The techniques and mechanistic interpretations of results are applicable to a variety of materials.

This is a powerful way to examine the interplay of characteristic relaxation times. Intervals of high point defect production and resultant processes, such as solute segregation and drift-directed clustering, are alternated with thermal annealing. Remarkable changes with respect to either steady bombardment or thermal aging at the same temperature can be produced. Figure 1(a) shows theoretically calculated fluctuating vacancy concentration in a steady irradiation.
Boron Precipitation and misfit dislocation structure in Si(Ge,B) buried epitaxial layers
Authors: Kola R.R. , Posthill J.B. , Rozgonyi G.A.
Published: June 2020

Heavily boron-doped silicon buried epitaxial layers are becoming increasingly important in the fabrication of thin membranes, three dimensional structures in silicon and latch-up free CMOS circuits. Si(Ge,B) co-doping has been utilized to compensate the B-induced lattice contraction in Si and hence buried high conducting layers which are strain-free and lattice matched to the Si substrate have been realized. The utilization of isoelectronic Ge also alters the point defect distribution in silicon resulting in reduced dopant diffusion which is an added advantage in realizing shallow junctions and reduced interfacial transition width in epitaxial layers. This contribution addresses the evolution of misfit dislocation structure and B precipitation behavior in heavily B-doped buried Si epitaxial layers. In addition, the effect of Ge co-doping on B solubility in Si will be discussed.

Silicon epitaxial layers were grown at 1080°C by chemical vapor deposition on 4-inch diameter p-type (100) substrates (10 and 0.04 Ω-cm) employing the SiH2Cl2-B2H6-GeH4-H2 chemical system. Single 5 μm thick epilayers and 2 μm buried layers with 4 μm intrinsic cap layers (10 Ω-cm) were grown.