bluuebunny/crossref_metadata_2025 huggingface dataset:
Blind Deconvolution to Aid Morphometrics of 3D Light Micrographs
Authors: Holmes T.J. , O’Connor N.J. , Szarowski D. , Bhattacharyya S. , Ancin H. , Holmes M. , Marko M. , Roysam B. , Turner J.N.
Published: June 2020

We are developing novel deconvolution algorithms for 3D light microscopy that include the widefield fluorescence, transmitted light brightfield and confocal fluorescence modalities. The main novelties that we have introduced are (1), the usage of maximum likelihood estimation as a mathematical optimization criterion and (2), incorporation of blind deconvolution such that the optical point spread function does not need to be measured (see references in 1,2).

Our recent research has included evaluations of performance. This includes validating the images, using artificial test objects of (reasonably) “known” geometry and evaluating the accuracy of morphometries that are aided by deconvolution. Test objects include microspheres and specially drawn, fluorescent filled micropipette tips. The performance measures are comparisons of various morphometries against chosen benchmarks Rat hippocampal neurons filled with lucifer yellow were used in evaluating performance with a biological sample. Morphometries obtained from nondeblurred and deblurred data sets, by way of automatic segmentation, were compared against benchmark measurements. The benchmarks, in these cases, were measurements obtained by way of the Stereocon software. The Stereocon software uses operator judgement to segment the object, and, in our case, uses the assumption that the dendrites have circular cross sections. This assumption provides a realistic benchmark measurement because it ensures that the thickness of the dendrites, on average, is isotropic. Some of these benchmark comparisons, with confocal fluorescence, are summarized in Table 1. Fig. 1 shows projectional images of the data sets from which some of these measurements were obtained. These data imply that incorporation of deconvolution methods will improve the accuracy of absolute morphometric measurements whenever automated segmentation schemes are embedded within the measurement process.
3D Microscopy: Confocal, Deconvolution or Both?
Authors: Pawley J. B. , Czymmek K.
Published: June 2020

Over the past 20 years great improvements have been made in the techniques available for doing 3D fluorescent microscopy on living cells. The first approach, generally referred to as image deconvolution, treats the stack of 2D widefield (WF) image data as merely the sum of a number of discrete point-spread functions (PSF) and uses the computer to find the array of emitters that, when blurred by the PSF, best fits the stored data. If the PSF is known, only presence of statistical and electronic noise in the data, prevents this best-fit set of emitters from being a perfect image of the dye distribution in the specimen. The crucial role played by noise can be appreciated by comparing images from the Hubbell space telescope in its original condition, even after deconvolution, with images taken after the optics had been repaired.

The second approach to 3D microscopy requires the introduction of a confocal aperture in front of the photodetector of a scanning laser microscope so that only the fluorescent signal emitted from the plane-offocus is recorded. As a result the image formed represents an “optical section” and a stack of such sections
can be recorded at different focus heights to produce a 3D data set.
Comparison of Techniques for EELS Mapping in Biology
Authors: Leapman R.D. , Andrews S.B.
Published: June 2020

Elemental mapping of biological specimens by electron energy loss spectroscopy (EELS) can be carried out both in the scanning transmission electron microscope (STEM), and in the energy-filtering transmission electron microscope (EFTEM). Choosing between these two approaches is complicated by the variety of specimens that are encountered (e.g., cells or macromolecules; cryosections, plastic sections or thin films) and by the range of elemental concentrations that occur (from a few percent down to a few parts per million). Our aim here is to consider the strengths of each technique for determining elemental distributions in these different types of specimen.

On one hand, it is desirable to collect a parallel EELS spectrum at each point in the specimen using the ‘spectrum-imaging’ technique in the STEM. This minimizes the electron dose and retains as much quantitative information as possible about the inelastic scattering processes in the specimen. On the other hand, collection times in the STEM are often limited by the detector read-out and by available probe current. For example, a 256 x 256 pixel image in the STEM takes at least 30 minutes to acquire with read-out time of 25 ms. The EFTEM is able to collect parallel image data using slow-scan CCD array detectors from as many as 1024 x 1024 pixels with integration times of a few seconds. Furthermore, the EFTEM has an available beam current in the µA range compared with just a few nA in the STEM. Indeed, for some applications this can result in a factor of ~100 shorter acquisition time for the EFTEM relative to the STEM. However, the EFTEM provides much less spectral information, so that the technique of choice ultimately depends on requirements for processing the spectrum at each pixel (viz., isolated edges vs. overlapping edges, uniform thickness vs. non-uniform thickness, molar vs. millimolar concentrations).
A Simple Correlative Technique for Morphologic and Energy-Dispersive Analysis of Glass-Mounted Paraffin Sections
Authors: Baker K. W. , King L. , Walker R. , Piscopo I. , Smith A.
Published: June 2020

Tissue sections, smears, and many other varied types of specimen are often mounted on glass slides for light microscopic (LM) evaluation and analysis. These same preparations’ using gold/palladiumcoated glass slides as specimen mounts, are also well suited to correlative scanning electron microscopy (SEM) and, energy dispersive X-ray analysis (SEM/EDX). The following short note describes a procedure for glass-mounted specimens that provides slides suitable for combined LM, SEM and SEM/EDX characterization. In addition, the method establishes a specimen-based reference point for the empirical determination of optimum electron probe depth and accelerating voltage for SEM/EDX analysis.

For illustrative purposes we used sections of mammalian kidney cortex known to be heavily laden with crystalline deposits of unknown structure and composition.

In each sample, birefringent crystalline material was initially observed in hematoxylin and eosinstained paraffin sections using bright field polarized light microscopy (Fig. 1).
Orientation Imaging of A Nb-Ti-Si Directionally Solidified In-Situ Composite
Authors: Sutliff J. A. , Bewlay B. P.
Published: June 2020

In this paper we report on the microstructural characterization of a directionally solidified (DS) Nb-Ti-Si alloy. The solidified ingot had a nominal composition of Nb-33 at%Ti-16 at% Si and was grown using the Czochralski technique with growth rate of 5 mm/min. The as-solidified ingot was approximately 50 mm long with a 10 mm diameter. The microstructure was examined using backscatter electron imaging and the microtexture of each of the phases was determined using the Electron BackScattering Pattern (EBSP) technique for electron diffraction in the scanning electron microscope. The details of the experiments are similar to those we have reported previously. Automated EBSP scans were acquired in order to map the local texture (microtexture) over most of a transverse cross-section through the ingot.

Figure 1 is a backscattered electron image (BEI) of a transverse section of the as-solidified microstructure. In this image, the bcc-Nb phase is the lighter gray phase and has a dendritic structure. The dark gray phase is (Nb,Ti)3Si having a Ti3P crystal structure. The silicide phase appears as both multiply-faceted dendrites and irregularly bounded grains. A pattern of shading, due to Ti segregation, can be seen in figure 1 and suggests a cellular solidification structure. Figure 2 is a BEI taken at higher magnification to show a region that was analyzed by automated-EBSP. Figure 3 contains orientation images generated from the automated-EBSP data set. In Figure 3a, the color black signifies positions for which no Nb diffraction patterns could be indexed and other shades of gray signify specific Nb orientations, as described by a set of Euler angles. A similarly generated orientation image for the silicide phase is shown in Figure 3b. The greyscale image presented here is actually a rendering of a truecolor image based on a RGB triplet using the Euler angles.
High-Temperature Instability of A Cr2Nb-Nb(Cr) Microlaminate Composite
Authors: Larsen M. , Rowe R.G. , Skelly D.W.
Published: June 2020

Microlaminate composites consisting of alternating layers of a high temperature intermetallic compound for elevated temperature strength and a ductile refractory metal for toughening may have uses in aircraft engine turbines. Microstructural stability at elevated temperatures is a crucial requirement for these composites. A microlaminate composite consisting of alternating layers of Cr2Nb and Nb(Cr) was produced by vapor phase deposition. The stability of the layers at elevated temperatures was investigated by cross-sectional TEM.

The as-deposited composite consists of layers of a Nb(Cr) solid solution with a composition in atomic percent of 91% Nb and 9% Cr. It has a bcc structure with highly elongated grains. Alternating with this Nb(Cr) layer is the Cr2Nb layer. However, this layer has deposited as a fine grain Cr(Nb) solid solution with a metastable bcc structure and a lattice parameter about half way between that of pure Nb and pure Cr. The atomic composition of this layer is 60% Cr and 40% Nb. The interface between the layers in the as-deposited condition appears very flat (figure 1). After a two hour, 1200 °C heat treatment, the metastable Cr(Nb) layer transforms to the Cr2Nb phase with the C15 cubic structure. Grain coarsening occurs in the Nb(Cr) layer and the interface between the layers roughen. The roughening of the interface is a prelude to an instability of the interface at higher heat treatment temperatures with perturbations of the Cr2Nb grains penetrating into the Nb(Cr) layer.
The Instructional SEM Laboratory at Iowa State University
Authors: Chumbley L. S. , Meyer M. , Fredrickson K. , Laabs F.C.
Published: June 2020

The Materials Science Department at Iowa State University has developed a laboratory designed to improve instruction in the use of the scanning electron microscope (SEM). The laboratory makes use of a computer network and a series of remote workstations in a classroom setting to provide students with increased hands-on access to the SEM. The laboratory has also been equipped such that distance learning via the internet can be achieved.

A view of the laboratory is shown in Figure 1. The laboratory consists of a JEOL 6100 SEM, a Macintosh Quadra computer that acts as a server for the network and controls the energy dispersive spectrometer (EDS), four Macintosh computers that act as remote workstations, and a fifth Macintosh that acts as an internet server. A schematic layout of the classroom is shown in Figure 2. The workstations are connected directly to the SEM to allow joystick and computer control of the microscope. An ethernet connection between the Quadra and the workstations allows students seated there to operate the EDS. Control of the microscope and joystick is passed between the workstations by a switch-box assembly that resides at the microscope console. When the switch-box assembly is activated a direct serial line is established between the specified workstation and the microscope via the SEM’s RS-232.
Remote Operation of a Scanning Electron Microscope (SEM) from Distant Classrooms
Authors: Smith N. R. , Tullis R. E. , Fegan N. , Morgan C. L.
Published: June 2020

California State University, Hayward (CSUH) has successfully demonstrated remote operation of a scanning electron microscope (SEM) using several networking interfaces. One of these methods is the use of highbandwidth asynchronous transfer mode (ATM). The different networking schemes have made it possible for instructors and researchers to access and control the Cal State Hayward SEM from classrooms located within the same building housing the microscope. In addition, the microscope has been remotely operated from across campus, from the local community college, and from San Jose State University.

The development of digital imaging technology provides opportunities of developing networking schemes for access and control of scientific instrumentation. The ability to network microscopes offers the capability of teaching microscopy methods to a large number of students at the same time. The traditional microscopy class includes the instructor training one student at a time while other students observe the operator of the instrument. Remote shared access to scientific instrumentation provides the advantages of a wider variety of resources and pooling of knowledge by a larger community.
SmartTilt: The Sensible Way of Tilting
Authors: Otten Max T.
Published: June 2020

Tilting a crystalline material in the Transmission Electron Microscope to bring it to a particular crystallographic orientation can be an experience that varies from the almost trivial (e.g. in the case of a large single-crystal piece of silicon in a semiconductor specimen) to something that frustrates even the most experienced operator (e.g. in the case of nanometre-sized crystals in a polycrystalline matrix). The problems encountered during such tilting experiments have to do mostly with the following characteristics of the double-tilt holder and goniometer of the microscope:

•

the second tilt is not eucentric

•

the mechanical characteristics of the goniometer and specimen holder are such that the forces applied by the tilt drive mechanism can lead to displacements ranging from a few to hundreds of nanometres

•

the tilt required commonly involves a combination of α and β tilts.

Normally the operator has to juggle to keep the crystal within the beam (by applying corrections to the x and/or z goniometer axes), set or adjust the tilt speeds for the α and β tilts, judge how much to tilt with α and β, and assess the result on the diffraction pattern. As a consequence, the whole procedure is normally done in increments, with many intermediate steps, corrections for overshoots, and so on. The time taken to tilt a particular crystal is inversely related to its size. For an experienced operator who knows the relative orientations of the diffraction pattern and the tilt direction, tilting a very small crystal sometimes can take up to tens of minutes. For an inexperienced operator, the procedure commonly results in losing track of the crystal and having to start over with another one.
Methods to Monitor and Improve the Performance of Specimen Holders for Transmission Electron Cryomicroscopy
Authors: Armbruster B. L. , Kraus B. , Pan M.
Published: June 2020

One goal in electron microscopy of biological specimens is to improve the quality of data to equal the resolution capabilities of modem transmission electron microscopes. Radiation damage and beam- induced movement caused by charging of the sample, low image contrast at high resolution, and sensitivity to external vibration and drift in side entry specimen holders limit the effective resolution one can achieve. Several methods have been developed to address these limitations: cryomethods are widely employed to preserve and stabilize specimens against some of the adverse effects of the vacuum and electron beam irradiation, spot-scan imaging reduces charging and associated beam-induced movement, and energy-filtered imaging removes the “fog” caused by inelastic scattering of electrons which is particularly pronounced in thick specimens.

Although most cryoholders can easily achieve a 3.4Å resolution specification, information perpendicular to the goniometer axis may be degraded due to vibration. Absolute drift after mechanical and thermal equilibration as well as drift after movement of a holder may cause loss of resolution in any direction.
An Integrated Energy-Filtering TEM for The Life Sciences
Authors: de Jong A.F. , Coppoolse H. , Lücken U. , Kundmann M.K. , Gubbens A.J. , Krivanek O.L.
Published: June 2020

Energy-filtered transmission electron microscopy (EFTEM) has many uses in life sciences1. These include improved contrast for imaging unstained, cryo or thick samples; improved diffraction for electron crystallography, and elemental mapping and analysis. We have developed a new system for biological EFTEM that combines advanced electron-optical performance with a high degree of automation. The system is based on the Philips CM series of microscopes and the Gatan post-column imaging filter (GIF). One combination particulary suited for the life sciences is that of the CM 120-BioTWIN and the GIF100: the CM120-BioFilter. The CM 120-BioTWIN is equipped with a high-contrast objective lens for biological samples. Its specially designed cold-trap, together with low-dose software, supports full cryo-microscopy. The GIF 100 is corrected for second-order aberrations in both images and spectra. It produces images that are isochromatic to within 1.5 eV at 120 keV and distorted by less than 2% over lk x lk pixels. All the elements of the filter are computer controlled. Images and spectra are detected by a TV camera or a multi-scan CCD camera, both of which are incorporated in the filter. All filter and camera functions are controlled from Digital Micrograph running on an Apple Power Macintosh.
A Study of Electrostatic Phase Plates using Electron Holography
Authors: Mohan A. , Frost B. G. , Joy D. C.
Published: June 2020

Contrast in transmission electron microscopy is normally provided by variations in the intensity of the transmitted electron beam, but weakly scattering objects such as biological tissue and polymers may not cause a sufficient change in amplitude to provide a useful image. The phase of the electron beam, however, is altered and if the phase change can be made to yield amplitude variation then the imaging can be carried out as desired. This can be accomplished by the use of some phase shifting device which alters the phase of the scattered wave by π/2 with respect to the unscattered wave. A number of such devices have been discussed in the literature but their design has typically been optimized empirically. One of the methods for performing Phase Contrast Microscopy in the TEM is by using an electrostatic phase plate in the back focal plane of the objective lens. This device consists of a charged fiber which causes small deviations in the ray paths of the scattered and the unscattered waves thus introducing a suitable phase shift between them.
Electron probe microanalysis of alumina-supported platinum catalysts
Authors: Lakis R. E. , Vicenzi E. P. , Allen F. M.
Published: June 2020

Conventional Electron-Probe Microanalysis (EPMA) requires fully dense, flat polished specimens, and similarly prepared standards of known composition. Most supported catalyst systems do not fit the above criterion, because porosity and large internal surface areas are intrinsic qualities of useful catalyst materials. Many catalysts of commercial importance contain a number of active metals and promoters that are impregnated into porous ceramic support with well controlled concentration profiles relative to the other constituents. It would be of great practical importance to reliably measure the distribution of active materials in a quantitative manner. A previous investigation which focused upon porous alumina, identified a deficit of detected electrons which increased with increasing porosity, and was perhaps due to the roughness of the porous materials surface. This leads to unrealistically low composition totals when traditional correction procedures are employed. This study is a first step towards the collection of high statistical quality data on catalyst materials so that new matrix correction procedures may be developed for these systems.
Electron energy loss near edge structures of intermetallic alloys and grain boundaries in NiAl
Authors: Botton G.A. , Humphreys C.J.
Published: June 2020

Transition metal aluminides are of great potential interest for high temperature structural applications. Although these materials exhibit good mechanical properties at high temperature, their use in industrial applications is often limited by their intrinsic room temperature brittleness. Whilst this particular yield behaviour is directly related to the defect structure, the properties of the defects (in particular the mobility of dislocations and the slip system on which these dislocations move) are ultimately determined by the electronic structure and bonding in these materials. The lack of ductility has been attributed, at least in part, to the mixed bonding character (metallic and covalent) as inferred from ab-initio calculations. In this work, we analyse energy loss spectra and discuss the features of the near edge structure in terms of the relevant electronic states in order to compare the predictions on bonding directly with spectroscopic experiments. In this process, we compare spectra of late transition metal (TM) to early TM aluminides (FeAl and TiAl) to assess whether differences in bonding can also be detected. This information is then discussed in terms of bonding changes at grain boundaries in NiAl.
Improving x-ray map resolution with image restoration techniques
Authors: Mott Richard B. , Friel John J. , Waldman Charles G.
Published: June 2020

X-rays are emitted from a relatively large volume in bulk samples, limiting the smallest features which are visible in X-ray maps. Beam spreading also hampers attempts to make geometric measurements of features based on their boundaries in X-ray maps. This has prompted recent interest in using low voltages, and consequently mapping L or M lines, in order to minimize the blurring of the maps.

An alternative strategy draws on the extensive work in image restoration (deblurring) developed in space science and astronomy since the 1960s. A recent example is the restoration of images from the Hubble Space Telescope prior to its new optics. Extensive literature exists on the theory of image restoration. The simplest case and its correspondence with X-ray mapping parameters is shown in Figures 1 and 2.

Using pixels much smaller than the X-ray volume, a small object of differing composition from the matrix generates a broad, low response. This shape corresponds to the point spread function (PSF). The observed X-ray map can be modeled as an “ideal” map, with an X-ray volume of zero, convolved with the PSF. Figure 2a shows the 1-dimensional case of a line profile across a thin layer. Figure 2b shows an idealized noise-free profile which is then convolved with the PSF to give the blurred profile of Figure 2c.
Methods and morality of digital manipulation of microscopic images
Authors: Kinnamon J. C. , Sherman-Crosby Terri A.
Published: June 2020

In recent years dramatic increases in both the computational power of personal computers and the ability of image enhancement software to “retouch” acquired images have provided the structural biologist with capabilities that were undreamed of less than a decade ago. Possessing the power to manipulate acquired images, however, does not necessarily mean that it is appropriate to do so. The goals of this presentation are: 1) to describe how images can be enhanced using commonly available software (e.g., Adobe Photoshop) and 2) to present some of the ethical issues related to the manipulation of microscopic images.

First of all, it should be stated that manipulating images did not begin with the introduction of the computer. The ability to adjust the appearance of microscopic images has been around as long as the darkroom. Several options for image manipulation were available to the skilled darkroom technician. One could adjust the contrast level by using different grades of paper, or increase the contrast level and sharpness or “snap” by using a point source illumination instead of an opal light source. A scratch on a negative might be covered by retouching the print using Spotone. Dodging and burning were used to even out poorly exposed images.
Unix-based workstations for digital image processing and analysis
Authors: Prestridge Eddie B.
Published: June 2020

The modern workstation, with its inherent high speed and massive memory, allows the use of complicated image analysis and processing algorithms and artificial intelligence programs not available to current PCs and mini-computers.

There is no single feature that differentiates the UNIX based workstation from a PC. Rather, it is its fundamental design that gives the workstation superior performance. This superiority in no small part is the result of the UNIX operating system. UNIX is a word that sometimes strikes fear into the hearts of mortal men! There is no reason to fear, however. Users of UNIX-based systems have no more interaction with the operating system than say users of WordPerfect running on a MS-DOS or MAC OS machine.

UNIX is the only operating system that runs on a wide range of systems from laptops to mainframes. It is unique in at least five areas: 1) massive data sets handling, 2) multitasking, 3) multi-user, 4) security, and 5) networking. Let me give you what I think are usable descriptions for these five areas.
The IBM-PC in electron microscopy
Authors: Mancuso James F.
Published: June 2020

IBM PC compatible computers are widely used in microscopy for applications ranging from control to image acquisition and analysis. The choice of IBM-PC based systems over competing computer platforms can be based on technical merit alone or on a number of factors relating to economics, availability of peripherals, management dictum, or simple personal preference.

IBM-PC got a strong “head start” by first dominating clerical, document processing and financial applications. The use of these computers spilled into the laboratory where the DOS based IBM-PC replaced mini-computers. Compared to minicomputer, the PC provided a more for cost-effective platform for applications in numerical analysis, engineering and design, instrument control, image acquisition and image processing. In addition, the sitewide use of a common PC platform could reduce the cost of training and support services relative to cases where many different computer platforms were used. This could be especially true for the microscopists who must use computers in both the laboratory and the office.
The role of mixed cubic/hexagonal nucleation layers on threading dislocation reduction in epitaxial GaN films
Authors: Wu X. H. , Brown L. M. , Kapolnek D. , Kellert S. , Kellert B. , DenBaars S.P. , Speck J.S.
Published: June 2020

The defect density and their configuration in epitaxial GaN films on sapphire are strongly related to the optical and electrical properties of the films. The crystalline quality of GaN on sapphire can be greatly improved by introducing a low temperature GaN buffer layer. However, recent studies in our group demonstrate that the pre-growth substrate treatment can significantly change the defects structure and electron properties of the films. In this paper, we present our results on studies of the film microstructures and their corresponding nucleation layers. We propose a novel mechanism for dislocation reduction for GaN on sapphire.

The growths for this study were achieved in a horizontal flow reactor operating at atmospheric pressure. Basal plane AI2O3 (Union Carbide) substrates were first cleaned in solvents and then heated in flowing H2 at 1050°C. Sample A was exposed to an ammonia flow of 3 1/min for 60s, sample B for 400s before the temperature was then reduced to 600°C and a nominal 190 Å thick GaN layer was grown.
Liquid-phase sintering of BN doped Fe-Cu/TiC composites
Authors: Durlu Nuri , Yao Nan , Milius David L. , Aksay Ilhan A.
Published: June 2020

Fe-Cu composites are commonly produced by liquid phase sintering (above the melting temperature of Cu, 1085°C). The wear resistance of these Fe-Cu alloys can be enhanced by introducing hard particles, e.g., TiC, into the matrix. In such cases, however, the densification of Fe-Cu/TiC composites by liquid phase sintering becomes difficult mainly due to the high wetting angle (110° at 1100-1200°C in argon) of liquid Cu with TiC particles. Especially when the amount of the TiC phase is high enough to form a continuous network of TiC grains, full densification is only achieved through hot pressing. We have recently overcome this problem in an [(Fe-4 wt% Cu) + 30 wt% TiC] composite by the addition of small amounts of BN. Composites with BN additives have been successfully sintered at 1275°C under vacuum or argon by additions of 1 wt% BN. Electron microscopic characterization of these composites has shown that this success is due to the modification of the liquid phase by the addition of BN, which also promotes the liquid phase sintering of the TiC phase.
HRTEM Study of Zircon from Eliseev Anorthosite Complex, Antarctica
Authors: Wirth R. , Kämpf H. , Höhndorf A.
Published: June 2020

Zircon is a common accessory mineral in magmatic, metamorphic and sedimentary rocks. The crystal structure is tetragonal with space group I41/amd. Zircon contains minor amounts of U and Th and can be dated by a variety of techniques yielding ages of crystallization, cooling, and redistribution of radioactive isotopes and their daughter products. The precision of the radiogenic age determination strongly depends on the ability of zircon to retain the daughter products which were produced by the radiogenic decay of U and Th.

Zircon-bearing rocks of this study are metamorphic oxide-apatite gabbronorites (OAGN) from the Eliseev Anorthosite Complex, Wohlthat-Massif, East Antarctica (Kampf et al., 1995). These unusual rocks are strongly enriched in accessory minerals (apatite: < 10 vol.%; zircon: < 1 vol.%, Owens & Dymek, 1992). Three steps in the evolution of these rocks are distinguished: a magmatic formation, followed by a granulite facies metamorphism and finally a tectonomagmatic overprint. The zircon crystals of this study are brown colored, up to 12 mm in length and up to 3 mm wide (Fig.1). Petrological investigations show that zircon has formed during the granulite facies event. Optical microscopy and cathodoluminiscence microscopy reveal a rhythmic zoning and many microcracks. The concentrations of uranium and thorium are low (U: 34-89 ppm and Th: 3-9 ppm). The radiation damage by radioactive decay of U and Th is expected to be minor due to the low uranium and thorium content.
Electron-microscopy studies of grain boundary phases and fracture in yttria-zirconia ceramics
Authors: Lash S.E. , Pham H. , Cooper A. , Mecartney M.L.
Published: June 2020

Trace amounts of intergranular silicate phases in zirconia ceramics are known to be significant factors in modifying the ionic conductivity of cubic yttria stabilized zirconia and in enhancing high temperature superplastic deformation behavior of tetragonal yttria stabilized zirconia. This work studies how the composition and distribution of the intergranular phase affect fracture.

Samples were prepared of yttria stabilized zirconia ceramics with 3 mol% yttria (3Y-TZP, metastable tetragonal zirconia) and 8 mol% yttria (8Y-FSZ, fully stabilized cubic zirconia). Additions of 1 wt.% of a barium silicate glass or a borosilicate glass were made prior to sintering so that different intergranular phases could be formed. Samples were sintered at 1400-1600°C for 2-21 h. SEM images of fracture surfaces were digitized and analyzed using Adobe Photoshop and Prismview programs.

Figure la shows the SEM analysis of a fracture surface of a 3Y-TZP sample sintered 1500°C for 10 hours. Transgranular fracture is indicated by the rough and wavy surfaces. Approximately 30% of the fracture is transgranular fracture.
Electron diffraction from anthracene
Authors: Tivol W. F. , Kim J. H.
Published: June 2020

Collection of a three-dimensional data set from anthracene illustrates some of the difficulties which can be encountered. Since the crystals are grown from solution their orientation is not certain, and the crystals are very bendy, so a range of orientations is encountered at a given tilt setting. Anthracene is moderately labile to irradiation, so care must be taken to avoid radiation damage during data collection. Anthracene will sublime at room temperature under vacuum, so the data must be collected at reduced temperature. Flat, well-ordered areas of the crystals are rare, so collection of high-resolution data is time-consuming. The thickness of the crystals is difficult to control, so finding areas which have minimal multiple scattering is also formidable.

The structure of anthracene is already known, so simulations of the diffraction patterns along various zone axes can be made. Cerius 2.0® was used to produce simulated zone axis patterns for all combinations of indices whose absolute values were 3 or less. The preferred orientation for the untilted grid is [102]. Scans of several preparations resulted in patterns which matched the simulation for [102]. The angles for each of the Miller planes with respect to [102] were calculated from the formula given by Dorset.
Decomposition of an Al-Cu-Ru quasi-crystal at 1420 K
Authors: Kitano Y. , Fujikawa Y. , Watanabe T.
Published: June 2020

Quasi–crystals of Al65Cu20RU15 alloy are known to be an icosahedral— phase (I— phase) of the F–type. This state has been confirmed to be stable near 1100 K, but perhaps not at temperatures higher than around 1300 K. In this paper we report high temperature behavior of this alloy. We have found that the stable I-phase would decompose into three or four phases at 1420 K, one of which is an I–phase having a different composition. We denote the lower temperature I–phase, I–phase(L), and this high temperature one, I–phase(H).

5N Al and Cu and 3N Ru were arc-melted in Ar. The nominal composition of the alloy was 65A1, 20Cu and 15Ru. In order to obtain homogeneous materials, the ingot was annealed at 1020 K for 100 hours. The X-ray powder diffraction pattern confirmed that the heat-treated ingot was only I-phase(L). This is the starting material in this study. DTA and EPMA analysis, and SEM and TEM observations were carried out in order to investigate subsequence thermal reaction. Experimental results with brief discussion are as follows.
Confocal imaging of calcium in intact ventricular muscle provides a new view of excitation-contraction coupling
Authors: Wier W.G.
Published: June 2020

A fundamentally new understanding of cardiac excitation-contraction (E-C) coupling is being developed from recent experimental work using confocal microscopy of single isolated heart cells. In particular, the transient change in intracellular free calcium ion concentration ([Ca2+]i transient) that activates muscle contraction is now viewed as resulting from the spatial and temporal summation of small (∼ 8 μm3), subcellular, stereotyped ‘local [Ca2+]i-transients' or, as they have been called, ‘calcium sparks'. This new understanding may be called ‘local control of E-C coupling'. The relevance to normal heart cell function of ‘local control, theory and the recent confocal data on spontaneous Ca2+ ‘sparks', and on electrically evoked local [Ca2+]i-transients has been unknown however, because the previous studies were all conducted on slack, internally perfused, single, enzymatically dissociated cardiac cells, at room temperature, usually with Cs+ replacing K+, and often in the presence of Ca2-channel blockers. The present work was undertaken to establish whether or not the concepts derived from these studies are in fact relevant to normal cardiac tissue under physiological conditions, by attempting to record local [Ca2+]i-transients, sparks (and Ca2+ waves) in intact, multi-cellular cardiac tissue.
Distensibility and wall composition of rat cerebral arterioles in hypertension induced by chronic blockade of nitric oxide synthase
Authors: Ghoneim S. M. , Chillon J. M. , Baumbach G.L.
Published: June 2020

We have previously reported that, during chronic hypertension, cerebral arterioles undergo hypertrophy of the vessel wall, accompanied by a paradoxical increase in passive distensibility. We have proposed that this increase may be due to a reduction in the proportion of nondistensible (collagen and basement membrane) to the distensible (smooth muscle, elastin and endothelium) components of the vessel wall. We have recently observed in stroke-prone spontaneously hypertensive rats(SHRSP), that an endothelium derived factor, endothelin, may contribute to hypertrophy, but not to increases in passive ditensibility, of cerebral arterioles vessel wall.

The goal of this study was to examine wall mass, composition and passive ditensibility of cerebral arterioles in chronic hypertension induced by decreased availability of another endothelium derived factor, nitric oxide (NO).

Four weeks old male Sprague-Dawley rats were treated with LG-nitro-L-arginine methyl ester (LNAME; 10 mg /kg/day) in the drinking water. We examined distensibility of maximally dilated cerebral arterioles in 4 months old Sprague-Dawley rats. Arterioles were then fixed at physiological pressure (2.25% gluterladehyde in 0.10 mol/L cacodylate buffer), the arteriolar segment used for distensibility measurements was removed then immerse fixed, rinsed briefly in 0.1 M cacodylate buffer, osmicated and processed routinely for electron microscopy (TEM).
Activation of isolated heterophils from chicks stimulated in vivo with salmonella enteritidis-immune lymphokines
Authors: Moyes R. B. , Droleskey R. E. , Kogut M. H. , DeLoach J. R.
Published: June 2020

Salmonella enteritidis (SE) is of great concern to the poultry industry due to the organism's ability to penetrate the intestinal mucosa of the laying hen and subsequently colonize the ovaries and yolk membrane. The resultant subclinical infection can lead to SE infection of raw eggs and egg products. Interference with the ability of the organism to invade has been linked to the activation and recruitment of inflammatory polymorphonuclear cells, heterophils, to the lamina propria of the intestinal tract.

Recently it has been established that heterophil activation and increased resistance to SE organ invasion can be accomplished by the administration of SE-immune lymphokines (SE-ILK) obtained from supernatants of concanavalin-A stimulated SE immune T lymphocytes from SE hyperimmunized hens. Invasion of SE into the lamina propria provides a secondary signal for directing activated heterophils to the site of SE invasion.
Cyprinella lutrensis gill lesions after exposure to terbufos
Authors: Messaad Ibrahim A. , Peters Edward J.
Published: June 2020

Terbufos (O, O-diethyl, S-(((1, 1-dimethylethyl)thio)methyl) phosphorodithioate), purity 98% acts as anticholinestrase. Commercial formulations are applied to soil as an insecticide-nematicide throughout the United States to control com root-worm larvae and other pests, preventing an economical loss to producers Terbufos is highly toxic to fish species (e.g., fathead minnows 96 hr's LC50 is 150 μg L−1) and toxicity increases as temperature increase. There have been no reports on its effects on fish gills.

Red shiners (Cyprinella lutrensis) were collected from the Platte River, Nebraska using a seine and maintained in 30-L glass aquaria (10 fish /tank) for a 14-d acclimation period at 22°C on a 12:12 photoperiod and fed a commercial fish food once daily except for 24-h before and at the beginning of bioassays. During the 14-d bioassay, fish were exposed to terbufos concentrations of 0, 1, 10, and 100μg L−1. At the conclusion of the bioassay, fish were fixed in 3% glutaraldehyde with 0.1 M phosphate buffer. Gills were removed, washed in 0.1 M phosphate buffer and post-fixed in 1% OsO4 for 2-h, gills were rinsed in water and dehydrated in a graded ethanol series. After critical point drying using liquid CO2, gill tissues were mounted on stubs, coated with gold-palladium and examined using a Cambridge S-90 stereoscan at 15 kV
Review of ultrastructural and histopathologic features of liver disease in α1-antitrypsin deficiency in a pediatric population
Authors: Barrish James P. , Hicks M. John
Published: June 2020

α1-antitrypsin (α1 AT) deficiency (serum concentration <11 μmol/L) is one of the most common hereditary disorders in the United States and Europe with an incidence of 1 in 2,000 Caucasians of northern European descent, α1AT is the major inhibitor of neutrophil elastase and is synthesized by the liver, released into the plasma and diffuses into organ systems thereby providing protection against the effects of neutrophil elastase. Deficiency of this antiprotease occurs when an aberrant homozygous form (most commonly PiZZ) is inherited. While α1 AT deficiency is associated with emphysema in adults, liver disease is seen most often in young α1 AT deficient children. Liver disease occurs in approximately 10% of neonates with o^AT deficiency, and this is characterized as a neonatal hepatitis syndrome with cholestasis, hepatosplenomegaly, conjugated hyperbilirubinemia, and elevated liver transaminases in a small for gestational age neonate. Typically, there is spontaneous regression of clinical symptoms by 6 months of age with persistence of mild biochemical abnormalities. However in about 3% of these neonates, the liver disease progresses resulting in cirrhosis and rapid onset of liver failure. Liver transplantation in these cases is the only alternative available.
Identification of a baculovirus polyhedron formation mutant with a novel phenotype
Authors: Slavicek James M. , Mercer Melissa J. , Kelly Mary Ellen
Published: June 2020

Nucleopolyhedroviruses (NPV, family Baculoviridae) produce two morphological forms, a budded virus form and a viral form that is occluded into a paracrystalline protein matrix. This structure is termed a polyhedron and is composed primarily of the protein polyhedrin. Insects are infected by NPVs after ingestion of the polyhedron and release of the occluded virions through dissolution of the polyhedron in the alkaline environment of the insect midgut. Early after infection the budded virus form is produced. It buds through the plasma membrane and then infects other cells. Later in the infection cycle the occluded form of the virus is generated (reviewed by Blissard and Rohrmann, 1990).

The processes of polyhedron formation and virion occlusion are likely to involve a number of viral gene products. However, only two genes, the polyhedrin gene and 25K FP gene, have been identified to date that are necessary for the wild type number of polyhedra to be formed and viral particles occluded.
Internal organisation of the nuclear pore complex by surface imaging with field emission in lens SEM (FEISEM)
Authors: Allen T.D. , Kiseleva E.V. , Goldberg M.W.
Published: June 2020

We have been working towards a 3 dimensional structural understanding of the Nuclear Pore Complex (NPC) with a view to investigating structural alterations associated with the molecular mechanism of transport across the nuclear envelope. FEISEM allows direct visualisation of changes in individual NPCs which will complement information from TEM 3D reconstructions. FEISEM has produced significant new information on the more peripheral elements of the NPC, most notably the nuclear pore basket or ‘fishtrap’ and the nuclear envelope lattice. NPC baskets have been recognised in both avian and insect species as well as amphibia and are likely to be evolutionarily conserved. In the salivary gland nuclei ofChironomusdifferent configurations of basket structure have been recognised undergoing interaction with Balbiani Ring particles during mRNA export. (Fig 1).

The ability to observe and directly compare large numbers of NPCs on isolated NEs from either the cytoplasmic or nucleoplasmicface, at equivalent biological resolution to TEM has enabled us to access internal NPC organisation by surface imaging.
Problems in observation of natural biological surfaces with high-resolution scanning electron microscopy
Authors: Hermann René , Müller Martin
Published: June 2020

High resolution scanning electron microscopy can contribute a lot to the understanding of events occurring on biological surfaces even at a molecular level (either natural or artificially produced surfaces, e.g. by freeze-fracturing). In order to reach this goal, significant structural elements, down to dimensions of 2 - 4 nm have to be preserved as a function of the physiological state. Cryotechniques are important tools to fulfil this task.

A natural biological surface is often not easily accessible to scanning electron microscopic observation. The surface is the part of the specimen where an exchange with the surroundings takes place. Removal or replacement of the surrounding medium can strongly influence the surface structure. Surrounding fluids normally contain non volatile components (only a few organsisms, e.g. yeasts, survive in distilled water without damage). Drying procedures - out of the native milieu - therefore result in deposition of solutes onto the specimen surface, sometimes mimiking natural biological structures.
Surface photoelectrochemistry using near-field scanning optical microscopy (NSOM)
Authors: Moyer Patrick J.
Published: June 2020

Near-field scanning optical microscopy (NSOM) has been used to characterize and modify surfaces with lateral spatial resolution as high as 50 nm. Some of these experiments were performed under electrochemical conditions. Progress towards this goal involved several important steps. They include proving adequate operation of the shear force feedback mechanism in liquids and fabrication of appropriate NSOM fiber probes.

With regards to shear force feedback, which is used to maintain the fiber probe within the near field of the sample, there has been ample discussion regarding the physics of the tip-sample interaction. It is important for biological and photoelectrochemical applications that the feedback mechanism operates successfully in liquid environments. Our results indicate that shear force operation in water allows for high spatial resolution NSOM characterization while providing high force sensitivity. When comparing the frequency spectra of the probe resonances in air and water, the water resonance is broadened. The broadened resonance peak when completely immersing the probe in water indicates an increase in damping.
Magnetic resonance investigations of blood: From hemoglobin to lymphocyte migration
Authors: Ho C.
Published: June 2020

We have applied various nuclear magnetic resonance (NMR) techniques, from high-resolution solution-state NMR spectroscopy to magnetic resonance imaging MRI), to investigate blood components such as hemoglobin and T-cells. We are interested in the structure-function relationship in human normal adult hemoglobin (Hb A) and in tracking the movement of T-cells in live rats. In this presentation, we shall give a brief summary of our approach and recent experimental results.

We have recently developed an expression system to produce authentic Hb A in Escherichia coli. With our Hb A expression plasmid (pHE2) (Fig. 1), we are in a position to produce any desired hemoglobin in E. coli. We are carrying out a study to learn the rules governing oxygen affinity and cooperativity of the oxygen binding process in hemoglobin. We have constructed several recombinant hemoglobins which exhibit varying degrees of oxygen affinity and cooperativity (as measured by the Hill coefficient).