bluuebunny/crossref_metadata_2025 huggingface dataset:
Atomic Force Microscopy Studies of Microstructure and Properties of Self Assembled Monolayers
Authors: Santiago Jecksan R , Barry Troughton E , Dennis Richard A , Russell Phillip E
Published: July 2020

Ex-situ and in-situ studies were performed for self-assembled monolayers (SAMs) formation on mica. The behavior of two surfactants [octadecylphosphonic acid (OPA) and dodecylphosphonic acid (DPA)] in two different solutions [ethanol or tetrahydrofuran (THF)] were studied at different concentrations. A cross section analysis of the monolayer images at partial coverage showed thickness of 1.8 nm, 0.7 nm, and 1.0 nm for OPA, DPA and mixed OPA/DPA, respectively. These values are similar to the ones presented by Xiao and those expected for a monolayer of mixed surfactants as proposed by Whitesides. Since the topography of a monolayer resembles the substrate, the presence of the monolayer at full coverage was determinated by force-distance curve measurements. It was observed that the solvent had the ability to re-dissolve the OPA monolayer, suggesting that the bonding is of a physisorption nature.
A Novel Preparation Method for High Resolution AFM Introduced With 2d-Streptavidin Crystals Grown on a Biotinlipid Monolayer
Authors: Scheuring Simon , Müller Daniel J , Ringler Philippe , Bernard Heymann J , Engel Andreas
Published: July 2020

The AFM (atomic force microscopy) requires a stable and flat substrate on which a biological sample is readily immobilized. For instance, membrane protein 2D crystals in lipid bilayers have been adsorbed to silanized glass with covalently attachment using a photocrosslinker or to mica by physisorption under appropriate ionic conditions. For the immobilization of 2D crystals of water soluble proteins formed on lipid monolayers, a different approach is required to attach the highly hydrophobic tails of the lipid molecules. To find a suitably hydrophobic substrate, the hydrophobicity of different materials was determined by the sitting drop method. Briefly, a 10 μ1 droplet of deionized and filtered water was deposited on the substrate surface and the diameter measured. Table 1 shows a decrease in droplet diameter with increasing hydrophobicity, indicating that substrates such as silanized glass and HOPG (highly ordered pyrolytic graphite) may be suitable for adsorbing lipid monolayers.
TEM Analysis of Deformation Zones in FIB-Prepared Samples of Microploughed Gold (100) and (111) Surfaces
Authors: Day R D , Dickerson R M , Maggiore C J , Brooks P M , Russell P E , Woodward T , Carter C B
Published: July 2020

To improve the understanding of the mechanical deformation mechanisms associated with friction, wear, and precision machining processes, a detailed set of microploughing experiments were performed on gold single crystal surfaces. Large single crystals that had an edge length of 1.5 mm and a thickness of 1 mm were used for this work. Since the microplough depths ranged from 100 nm to 1600 nm, it was important that the material be damage free at the surface. This condition was verified by alpha particle backscattering. A stand-alone STM head, having a singlecrystal diamond tip, was used in conjunction with a Digital Instruments Nanoscope Ilia controller to generate the 13 μm long microploughs. The vertical ploughing force was measured using a Mettler AE130 semi-microbalance.

After generating the microploughs and measuring their geometry with an AFM, some of the microploughs were cross sectioned for TEM observation.
Scanning Kelvin Force and Capacitance Microscopy Applications
Authors: Kline RJ , Richards JF , Russell PE
Published: July 2020

Scanning Probe Microscopy (SPM) is being developed as a possible solution to the problems inherent with analyzing the nanometer scale electronic properties of ULSI integrated circuits. Scanning Kelvin Probe Microscopy (SKPM) and Scanning Capacitance Microscopy (SCM) are both being developed to provide two dimensional dopant profiles of semiconductor devices. SKPM can also determine surface potentials, work functions, dielectric properties, and capacitance.

SKPM is based on the concept of Kelvin probe oscillating capacitor work function measurements. The small capacitance area of the SKPM tip and the high resistance of the system produce difficulties in monitoring and minimizing the current in the system. SKPM solves this problem by utilizing the force monitoring capability of the SPM to minimize the Kelvin force instead of the current. An AC voltage applied to the cantilever produces a DC force and AC forces at the AC frequency and the first harmonic of the AC frequency.
Mapping the Organic and Inorganic Components of Normal and Osteoporotic Bone Using Nexafs.
Authors: Buckley C J , Khaleque N , Bellamy SJ , Dermody G , Robins M , Zhang X
Published: July 2020

Ultra-thin unstained sections of femoral neck bone from normal and ovariectomised mice were imaged in a scanning transmission x-ray microscope. The images were formed using soft x-ray energies at the calcium L and carbon K edges. The aim of the study was to quantitatively map the calcium, protein and embedding medium in normal and ovariectomised (osteoporotic) mice to compare the quantity and distribution of mineral (via calcium), collagen (via protein) and hydrated content (via embedding medium substitution).

A set of seven images were taken of both the normal and ovariectomised mouse sections. These images were processed using x-ray optical constants to produce mass thickness maps. The thickness of the sections from the normal mouse and ovariectomised mice were 205nm and 375nm respectively. The images show embedding medium, protein and calcium maps of near complete sections of the majority of the femoral neck at equivalent neck positions in the normal (la, 2a & 3a) and ovariectomised (lb, 2b & 3b) mouse bone sections.
Quantitative Non-Interferometric X-Ray Phase Imaging
Authors: Nugent KA , Paganin D , Tiller J , Allman B
Published: July 2020

The phase of a coherent wave is an intuitively well understood concept and efforts to measure the phase of a wave are a staple of visible, x-ray, electron and atom optics. However, in a subtle way, phase is often measured where it is not even defined. An example of this is adaptive optics where the atmospheric phase distortion of light from astronomical objects is measured using polychromatic light. The assumption buried under this work is that it is possible to sensibly talk about phase even though the context of the discussion does not permit phase to be defined according to elementary concepts.

We have been undertaking an ongoing program investigating the nature of wavefields and exploring their characterisation using more robust approaches than standard techniques such as interferometry In a very recent paper we have developed a new viewpoint on phase defined via the Poynting vector of the radiation and where the phase acts as a set of potentials leading to the Poynting vector field.
A State-of-the-art X-Ray Microprobe and its Applications at the Advanced Photon Source
Authors: Yun W , Cai Z , Lai B , Maser J , Legnini D
Published: July 2020

We have developed a state-of-the-art x-ray microprobe with many unprecedented capabilities for a broad range of scientific applications. The combination of the high brilliance third-generation synchrotron radiation sources and the development of high performance x-ray focusing optics have led to the construction of a x-ray microprobe at Argonne National Laboratory with a FWHM focal size less than 0.25 μm and photon flux exceeding 5×l010 photons/cm2/sec/0.01% BW. The microprobe is very flexible and versatile and can be used simultaneously to perform x-ray diffraction microscopy, fluorescence microscopy, spectromicroscopy, and 3D tomography with submicron spatial resolution. It has been used for a broad range of applications since its commissioning in December of 1996. For example, it was used in the study of the symbiotic relation between plant root and fungi, platinum-based anticancer agents, integrated laser/modulator microdevices, electromigration in Al wires in semiconductor devices, and submicron spatial resolution threedimensional tomography of a single cell. The capabilities of the microprobe are described below, and applications using these capabilities will be presented.
Precise X-Ray Microfluorescence Measurements of Sr/Ca Ratios In Corals For Paleotemperature Analysis
Authors: Pingitore Nicholas E , Pogue Ted
Published: July 2020

Coral aragonite encodes a rich, complex record of ambient environmental conditions (including temperature, salinity, pollutants) during skeletogenesis. Annual growth banding in appropriate species provides an internal calendar, and the rapidity of skeletal growth permits temporal sampling to at least a sub-monthly basis. The longevity of reef coral colonies can provide continuous centuries-long environmental records. The presence of well-dated Pleistocene coral reefs at sites across the world ocean extends this record into the more distant past. Thus corals are a remarkable resource for the investigation of environmental conditions over perhaps 7 orders of magnitude of time.

The past few years have seen considerable use of Sr/Ca ratios in scleractinian corals to reconstruct sea surface temperatures (SSTs) to document global change. The detailed correlation between Sr/Ca ratios in living corals and measured ambient water temperature is often remarkable, as is the match in older corals between Sr/Ca ratios and such other SST temperature proxies as 18O /16O ratios.
Bragg and Fresnel Diffraction Imaging Using Highly Coherent X-Rays
Authors: Cloetens P , Baruchel J , Guigay JP , Ludwig W , Mancini L , Pemot P , Schlenker M
Published: July 2020

X-ray imaging started over a century ago. For several decades its only form was absorption radiography, in which contrast is due to local variations in beam attenuation. About forty years ago, a new form of X-ray imagery, Bragg-diffraction imaging or X-ray topography, developed into practical use. It directly reveals crystal defects in the bulk of large single crystals, and paved the way to microelectronics by leading to the growth of large, practically perfect, crystals. The advent of third-generation synchrotron radiation sources of X-rays such as ESRF and APS is now making possible, through the coherence of the X-ray beams, a novel form of radiography, in which contrast arises from phase variations across the transmitted beam, associated with optical path length differences, through Fresnel diffraction. Phase radiography and its three-dimensional companion, X-ray phase tomography, are providing new information on the mechanics of composites as well as on biological materials.
Recent Developments In Monochromatic Microprobe X-Ray Fluorescence (MMXRF)
Authors: Chen Z W , Wittry D B
Published: July 2020

A monochromatic x-ray microprobe based on a laboratory source has recently been developed in our laboratory and used for fluorescence excitation. This technique provides high sensitivity (ppm to ppb), nondestructive, quantitative microanalysis with minimum sample preparation and does not require a high vacuum specimen chamber. It is expected that this technique (MMXRF) will have important applications in materials science, geological sciences and biological science.

Three-dimensional focusing of x-rays can be obtained by using diffraction from doubly curved crystals. In our MMXRF setup, a small x-ray source was produced by the bombardment of a selected target with a focused electron beam and a toroidal mica diffractor with Johann pointfocusing geometry was used to focus characteristic x-rays from the source. In the previous work ∼ 108 photons/s were obtained in a Cu Kα probe of 75 μm × 43 μm in the specimen plane using the fifth order reflection of the (002) planes of mica.
Experimental Gun Brightness Measurements on a 300 kV CFEG
Authors: Zaluzec Nestor J , Nicholls Alan
Published: July 2020

Effective use of the ANL 300kV CFEG/A AEM requires a knowledge of the probe current and size distribution during operation. In most cases this can be calculated once basic parameters of the system are experimentally determined. Central to this is a determination of the source brightness of the Cold Field Emission Gun (CFEG) under standard operating conditions of the instrument. For the last ten years most probe calculations of CFEG's have been done assuming a brightness parameter of β∼×109 A/cm2/sterad2 at 100 kV, while few if any experimental values have been reported at 300 kV. Using β and the relationship that the operating probe diameter is obtained by adding in quadrature the Gaussian probe size (dg, the CFEG source contribution), and the diameters of least confusion due to spherical abberation (ds) and diffraction limits (dd) one obtains the total probe size dt as :
Measuring and Tuning TEM Energy Filter Performance
Authors: Brink H , Kothleitner G , Kundmann MK
Published: July 2020

Although, critical performance criteria of TEM objective lenses, such as spherical and chromatic aberration and, more recently, 3-fold astigmatism, are of common concern, the important properties of TEM energy filters are less well-known and not often measured or quoted. In an effort to bring these to light, we have developed methods for automatically measuring and tuning three optical properties important to practical filter performance: non-isochromaticity, geometric distortion, and non-achromaticity.

A filter is perfectly isochromatic if the range of electron energies that contribute to an energy-filtered image is the same across all image pixels. In practice, energy filters display some degree of nonisochromaticity, i.e. the energy-loss range forming the periphery of the image differs by anywhere from a fraction of an eV to as much as few eV from that forming the center of the field of view.
Energy Filtering Imaging Of Thick Biological Specimens With In-Column "Omega"-Filter Microscopes.
Authors: Ellisman Mark H , Fan GY , Honda T , Kanayama T , Kersker M
Published: July 2020

Preliminary results were obtained from thick sections of biological specimens using 200 keV electron microscopes with an in-column “Omega” energy filter. Images of selectively stained specimens prepared by osmium impregnation of frog spinal ganglia, with thickness ranging from 0.5 μm to 2.5 μm, show drastic improvement in image quality with the use of the energy filter.

Two instruments with Omega filters were used. One was a non-commercial research prototype at JEOL Ltd. equipped with a LaB6 gun and the other was a commercial instrument (JEM-2010FEF) with a field-emission gun, installed at Kyushu University. We found that, although the field-emission gun offered a brightness 2 to 3 orders of magnitude higher, the LaB6 gun was more suitable for studying thick specimens, primarily due to the higher beam current of the LaB6 gun.
Magnetic Deflecting Microscopy: A Novel Visualizing Method of Magnetic Stray Fields for Thick or Non-Transparent Magnetic TEM Samples
Authors: Volkov VV , Zhu Y
Published: July 2020

For microstructure analysis of magnetic materials, in particular, for a new class of Nd-Fe-B hard magnets, a number of magnetic imaging techniques can be applied to gain different microstructure information. For instance, SEM magnetic imaging can be successfully used for very thick samples from a bulk ones down to a sample thickness of 10-20 μ. Below this limit the resolution of SEM magnetic images generally is too low to visualize fine details of magnetic structure. For very thin samples (less then 0.5 μm) magnetic Lorentz microscopy methods in conventional TEM are very useful tools to reveal magnetic domains and their structure. Therefore, it seems that relatively thick films of 0.5-20 μm in thickness are left out of the experimental limits of the methods discussed.

We report on a novel, indirect TEM method that allows us to extend the limits of magnetic imaging for TEM non-transparent magnetic samples by viewing the surface stray fields and fringing fields generated by magnetic domains at specimen edge.
An Infinity Corrected All-Reflecting Microscope for Infrared Microspectrometry
Authors: Reffher John A , Vogel Steven H
Published: July 2020

A confocal, all-reflecting, infinity corrected microscope was developed to improve infrared microspectrometer (IMS) systems. This system consists of a Fourier transform spectrometer, an infinity corrected all-reflecting microscope, a viewing system for visible light microscopy, a single remote confocal mask for aperturing in either a transmission or reflection mode and an infrared detector. The radiant energy passes through a confocal aperture mask as it travels from the source to the sample and through the same confocal aperture mask as it travels from the sample to the radiant energy detector. A single confocal mask insures that the sample defining mask's size, geometrical shape and orientation are always matched. Mask alignment is assured and simplified since only one adjustment is needed. An aperture beam-splitter is used for reflection measurements. This system simplifies the operation of the microspectrometer, permits the use of standard commercial infinity corrected microscope optical components and reduces the cost of IMS accessory microscopes.
High-Qe Photodetector for Laser Confocal
Authors: Pawley J , Blouke M , Janesick J
Published: July 2020

The laser confocal microscope (LCM) is now an established research tool in biology and materials science. In biological applications, it is usually employed to detect the location of fluorescent marker molecules and, under these conditions, detected signal levels from bright areas often represent <20 photons/pixel (assuming a standard 1.6 μs pixel time) while those from dark areas are likely to average <1 photon/pixel. Although this data rate limits the speed at which information can be derived from the specimen, saturation of the fluorophor, photobleaching of the dye, and phototoxicity often prevent it being increased by simply using more laser power. Over the past 10 years, the optical photon efficiency of commercial confocal instruments has improved significantly and it is now reaching the point where further improvement is becoming very expensive. The only component is which a significant improvement is still possible is the photodetector.
Video-Rate Scanning Two-Photon Excitation Fluorescence Microscopy
Authors: Fan GY , Fujisaki H , Tsay R-K , Tsien RY , Ellisman Mark H
Published: July 2020

A video-rate scanning two-photon excitation microscope (TPEM) has been successfully constructed and tested. The TPEM, based on a Nikon RCM-8000, incorporates a femtosecond pulsed laser, a pre-chirper, and a non-confocal detection box for ratio imaging. Fig. 1 shows the schematic layout of the main components of the instrument, each of which is briefly discussed below.

Laser System: A Tsunami Ti: Sapphire laser (from Spectra-Physics) is optically pumped by a 5 W green laser (Millennia from Spectra-Physics) and is capable of generating 100 fs pulses at a repetition rate of 82 MHz and an average power of 0.8 W. The output wavelength is tunable from 690 to 1050 nm with three optical sets, each covering part of the spectrum with some overlapping.

Pre-chirper: After leaving the Tsunami, the laser beam enters an optic unit known as a pre-chirper which pre-chirps laser pulses to compensate for the group velocity dispersion which will result when the laser beam goes through the microscope optics.
Electron Tomographic Studies of a Large Macromolecular Assembly Preserved In Vitreous Ice: The Yeast Spindle Pole Body Core
Authors: Bullitt E
Published: July 2020

Advances in both electron cryomicroscopy and tomographic reconstruction methods have made it possible to collect and analyze data from large macromolecular assemblies frozen without fixation, sectioning, or staining. The Spindle Pole Body (SPB) is the microtubule organizing center in the yeast Saccharomyces, and is involved in mitosis, nuclear movement, budding, and mating. We have used electron cryomicroscopy and tomographic reconstruction to investigate the 1500Å diameter, 600Å high cylindrical core structure produced by limited heparin treatment of isolated SPBs.

Tilt series' of SPB cores preserved in vitreous ice were taken under low electron dose conditions. These images have been analyzed using iterative correlation alignment and computed back projections for tilt data without fiducial markers. In these studies, electron micrographs were digitized, and translationally aligned using correlation methods.
The Three Dimensional Organization of Smooth Muscle: Information from Serial Section Reconstructions
Authors: Horowitz RA , Powers CM , Valero P , Craig R
Published: July 2020

Smooth muscle is a machine consisting of working and supporting elements whose structure and 3D organization must be elucidated for the mechanics of shortening and tension generation to be understood. Based on longitudinal and serial transverse sections of rabbit portal vein it was suggested that the contractile elements of smooth muscle formed “mini-sarcomeres”, analogous to skeletal muscle, containing parallel arrays of 3-5 myosin filaments 1.6-2.2 um long. Observations at the light microscopic level were consistent with this idea. The past decade has seen little further investigation into the in situ ultrastructure of this or other smooth muscles, and the general applicability of these findings remains unknown. We have taken advantage of recent methodological advances, which can provide full 3D computer representations of cellular organization based on EM data, using guinea pig taenia coli muscle as a model system.

Serial transverse sections (Fig 1) were used to generate 3D reconstructions of the organization of the myosin filaments and their relation to dense bodies, actin bundles, mitochondria and other organelles.
Quantitative Image Processing in 3D
Authors: Skoglund Ulf
Published: July 2020

Three-dimensional reconstructions from projections are usually ridden by noise from different sources. A common problem among many three-dimensional reconstruction techniques is the systematic absence of certain projections, but also the accidental absence of spurious projections. In these three-dimensional reconstructions such absences are visible as directional smearing due to convolution. Other convolution effects such as those due to the optics of the instrument used to record the data usually cause severe damping of high frequencies and even contrast reversal (common in images from electron microscopes).

Several approaches to overcome these ‘noise’ effects in three-dimensional reconstructions have been developed, but they usually suffer from the very small radius of convergence. Very easily and commonly, the refinement iterations end up stuck in a premature choice of a minimum. We have developed another algorithm, constrained maximum entropy tomography (COMET), that in practice has been shown to overcome these problems.
Fluorescent Indicators for Calcium Based on Green Fluorescent Proteins (GFPs) and Calmodulin
Authors: Miyawaki A , Llopis J , Heim R , McCafFery JM , Adams JA , Ikura M , Fujisaki H , Fan GY , Ellisman MH , Tsien RY
Published: July 2020

Cytosolic and organellar free Ca2+ concentrations are very dynamic; they are often extremely localized and hard to measure. To overcome this problem we have constructed new fluorescent indicators for Ca2+ that are genetically encoded without cofactors and are targetable to specific intracellular locations.

Green fluorescent protein (GFP) is a spontaneously fluorescent protein from the jelly fish Aequorea victoria. Its cDNA can be concatenated with those encoding many other proteins, and the resulting fusion proteins are usually fluorescent and often preserve the biochemical functions and cellular localizations of the partner proteins. Mutagenesis has produced GFP mutants with shifted wavelengths of excitation or emission that can serve as donors and acceptors for fluorescence resonance energy transfer (FRET).

Our new indicators consist of tandem fusions of a blue- or cyan-emitting mutant of GFP, calmodulin (CaM), the calmodulin-binding peptide Ml3, and an enhanced green- or yellow-emitting GFP. Binding of Ca2+ makes calmodulin wrap around the Ml3 domain, increasing the FRET between the flanking GFPs (Fig. 1).
Correlative Confocal and Electron Microscopy of the Connexin43 Gap Junction Protein in NRK Cells: Balancing Fixation Conditions, Cell Permeabilization, Antigen-Antibody Interaction and Cell Ultrastructure.
Authors: Sosinsky Gina , Martone Maryann , Handel Galen , Musil Linda , Ellisman Mark
Published: July 2020

Synthesis and assembly of gap junction proteins into intercellular channels is an important biological problem with direct bearing on embryonic development. In particular, transgenic mice Cx43 gap junction protein knock-outs 1 and mutations in Cx43 sequence in human Viscera Hyper Taxia patients result in severely deformed hearts.

NRK cells are one of the best studied systems for gap junction synthesis, transport and assembly. Gap junctions contain numerous cell-cell channels which are composed of two paired oligomers (called a connexon or hemichannel) each contributed from the plasma membrane of apposing cells. Although biochemical studies have shown indirectly that unpaired Cx43 connexons are in the plasma membrane, direct hemichannel visualization has not been demonstrated. Musil and Goodenough have shown that oligomerization occurs in the trans-Golgi network and the connexon is transported to the plasma membrane.
Structure of the Calcium Pump from Sarcoplasmic Reticulum at 8 Å Resolution: Architecture of the Transmembrane Helices and Localization of the Binding Site for Thapsigargin
Authors: Zhang P , Toyoshima C , Yonekura K , Inesi G , Green M , Stokes DL
Published: July 2020

The calcium pump (Ca2+-ATPase) from sarcoplasmic reticulum (SR) is a prominent member of the large family of ATP-dependent cation pumps, which include Na+ /K+-ATPase, H+/K+-ATPase from the stomach, H+-ATPase from yeast and Neurospora, and various detoxifying pumps for Cd+, Cu+ and other metals. In muscle, calcium is stored inside the SR and contraction is initiated by regulated release through specific calcium channels; Ca2+ -ATPase is responsible for relaxation by pumping calcium back into the SR lumen. Many techniques (chemical modification, site mutagenesis, reaction kinetics) have been used to correlate Ca2+-ATPase sequence with function, but no high resolution three-dimensional structure of Ca2+-ATPase, or any P-type pump, has yet been determined. In the current work, we have determined the structure from helical crystals at 8 A resolution and thus revealed the alpha-helical architecture of the transmembrane domain. In addition, a specific inhibitor of Ca2+-ATPase, thapsigargin, was used to promote crystallization and we have characterized the structural consequences of its inhibition.
Shared Research Equipment at OAK Ridge National Laboratory
Authors: Evans N D , Kenik E A , Miller M K
Published: July 2020

The Shared Research Equipment (SHaRE) User Facility and Program at Oak Ridge National Laboratory (ORNL) provides microanalytical facilities for studies within the materials sciences. Available instrumentation includes advanced analytical electron microscopes, atom probe field ion microscopes, and nanoindentation facilities. Through SHaRE, researchers from U.S. universities, industries, and government laboratories may collaborate with Facility scientists to perform research not possible at their home institutions. International collaborations are also possible. Most SHaRE projects seek correlations at the microscopic or atomic scale between structure and properties in a wide range of metallic, ceramic, and other structural materials. Typical research projects include studies of magnetic materials, advanced alloys, catalysts, semiconductor device materials, high Tc superconductors, and surface-modified polymers. Projects usually involve one or more external researchers visiting the SHaRE Facility for up to three weeks during the fiscal year (October 1 - September 30). Project approval is based upon the scientific excellence and relevance of proposed collaborative research.
Microscopical Examination of Indoor Dusts
Authors: Millette J R , Few P , Hopen T J
Published: July 2020

Several case studies are shown as examples of the results of analyses using various microscopical instruments to characterize the particles in building dusts. Characterizing the particles and identifying possible sources of particles in dusts are often important parts of solving indoor indoor air quality (IAQ) and environmental problems. Samples of the dust particles can be collected by filtering the air with cassette air filters or by gathering the dust that has accumulated on surfaces. Depending on the size and types of particles in the dust either polarized light microscopy (PLM), scanning electron microscopy with x-ray analysis (SEM/EDS), analytical transmission electron microscopy (ATEM) or Fourier transform infrared microspectroscopy (FTIR) may be used solely or in combination. PLM can characterize most of the common dust particle in residential and commercial buildings. SEM/EDS is helpful in identifying metal particles and when used in the backscatter electron mode, a large number of particles can be surveyed and those containing heavy metals such as lead and cadmium can be identified quickly.
Production Microscopy: A New Paradigm
Authors: Lee Richard J
Published: July 2020

During the past twelve months RJ Lee Group has manually collected and published over one hundred thousand composite SEM images consisting of three components: a low magnification image, a high magnification image, and an x-ray spectrum. In addition, about one and one-half million discrete features have been automatically located and compositionally/morphologically characterized, with about one-fourth of those features then having ancillary images collected automatically based upon characterization criteria. Finally between ten and twenty thousand images have been collected for the production of image montages. The output of this effort has been systematically entered into networked databases where it is accessed for post-processing, analysis, and report generation.
Population Studies of Titanium-Bearing Inclusions in AISI 316l using Automated Image Analysis with Scanning Electron Microscopy/Electron Dispersion Spectroscopy (SEM/EDS)
Authors: Collins S R , Plishka M
Published: July 2020

Titanium is used in the manufacture of AISI 316L austenitic stainless steel as a deoxidizer. Titanium is considered a residual element, and limits are often not specified. As a residual element, titanium most often appears in complex oxide inclusions, usually in conjunction with aluminum and other deoxidizers. Titanium-bearing inclusions have been found to initiate pitting during electropolishing. The present work was performed to evaluate the acceptable upper limit for titanium as a residual element in AISI 316L.

Metallographic specimens were prepared from seven commercial heats of AISI 316L (Table 1) with titanium contents varying from 0.003 % to 0.014 %. A quantitative metallographic analysis of each specimen was performed using an SEM/EDS system with an automated stage. Operating parameters are given in Table 2. Data was obtained with the system in the backscatter (BS) mode, producing a high-contrast image based on differences in chemical composition. Once each inclusion was identified by its difference in gray scale, it was also analyzed by EDS for elements present.
Microanalysis of Thermal-Sprayed Titanium Anodes for Cathodic Protection of Reinforced Concrete Bridges
Authors: Collins W K , Cramer S D , Covino B S , Holcomb G R , Bullard S J , Govier R D , Wilson R D , McGill G E
Published: July 2020

This paper addresses the microanalysis techniques used to characterize thermal sprayed Ti coatings on concrete surfaces as anodes in impressed current cathodic protection (ICCP) systems. Thermal sprayed Ti anodes on concrete were electrochemically aged in laboratory studies of anode performance and service life. A thermal sprayed catalyzed Ti anode was installed on the Depoe Bay Bridge on the Oregon Coast in a field demonstration of the ICCP system. Both air and N were used as the atomizing gases during the study. Thermal sprayed Ti coatings are typically applied in an inert atmosphere or vacuum using shrouds or chambers to prevent reactions with the atmosphere. This was not possible with a structure as large as a bridge.

Microanalysis of Ti and N together is difficult and the effects of O add to the complexity of the analysis. The ternary Ti-O-N system has not be well studied.
Low Energy X-Ray Transmission Images by using a Microfocus X-Ray Tube and a be-Window X-Ray Image Intensifier(XRII)
Authors: Konuma H , Kuroki K , Kurosawa K , Saitoh N
Published: July 2020

Photographs of x-ray transmission images by x-ray films have been used for observing the inside nondestructively. Further, Imaging Plates(IP) are used for precise measurements of x-ray diffraction patterns. But, these integrating area detectors are not suitable for real time nor time resolved measurements. For real time and time resolved measurements, the X-Ray Image Intensifier(XRII, a large image tube that converts an x-ray image into a visible image) is used for biological x-ray TV systems, x-ray nondestructive inspection systems etc. These TV x-ray image systems require high energy x-rays, x-ray tube voltage of 30 to 150 kV, and show faint contrast for x-ray images of light element substances owing to its low absorption coefficients. However, light elements have intense x-ray absorption coefficients in a low energy x-ray region, x-ray tube voltage of 5 to 20 kV, and give fine contrast for x-ray images of light element substances.
Examination of the Surface of a Maldi-Ftms Probe Tip using SEM and Determination of Detection Limits for Poly(Ethylene Glycol)
Authors: Wood Sylvia H , Pastor Salvador J , Wilkins Charles L
Published: July 2020

Exploratory synthetic strategies may yield limited quantities of sample. Characterization of such limited-quantity samples is facilitated by the use of sensitive analytical methods and smart sample preparation. Polymers may be analyzed by mass spectrometry for molecular weight distributions, structural information (such as endgroups), and impurities. However, polymer research using mass spectrometry has not focused on detection limits; in some work the amount of polymer used is not even mentioned. Studies to determine detection limits of polymers and studies that characterize sample preparation techniques can provide valuable information.

Examination of the sample surface on a probe tip, generated by the use of an aerospray technique for sample deposition, was accomplished by scanning electron microscopy (SEM). Aerospraying the polymer and matrix solutions allowed signal averaging of mass spectra from up to 400 shots on the same sample spot. SEM images showed the surface of the probe to have a fairly uniform coating of the sample and matrix.
Binding of Polychlorinated Biphenyls to Sediment
Authors: Tivol William F , Casey Ann C , Liu Xuemei , Bush Brian
Published: July 2020

Transport, cleanup, and bioremediation properties of polychlorinated biphenyls (PCBs) bound to sediments depend on the specific components to which the PCBs are bound. Analysis of the sediment from Contaminant Cove on the St. Lawrence River by gas chromatography with an electron capture detector shows that the sediment contains 600 ppm PCBs. Previous work showed that there were both weak and strong binding of PCBs to sediment components, but gave no indication of which components were responsible for the binding.2 The average content of PCBs is below the limit of detectability by energy-dispersive x-ray microanalysis (EDX) for CI, but constituents which bind large quantities of PCBs could be detected. Sediment which is not contaminated with PCBs contains no detectable chlorine.

EDX analysis was performed on a JEOL JEM-4000FX, using a cryo-stage (operated at -160° C) and a Tracor TN5500 system.
Raman Microprobe Study of the Visible and Near-Infrared Excited Fluorescence Spectra of Glasses Examined as Potential Raman Intensity Calibration Standards
Authors: Etz Edgar S , Choquette Steven J , Hurst Wilbur S , Blackburn Douglas H
Published: July 2020

In previous work with the Raman microprobe, we have examined the fluorescence emissions of rareearth (RE) bearing glasses to study the phenomena of structural resonances in the spectra of glass microspheres and the energy upconversion processes for RE ions in such glasses that give rise to anti- Stokes fluorescence emission. Presently, we are revisiting these same fluorescent glasses to study their laser excited emissions as potential radiometric sources for the calibration of Raman spectral intensities. Many of the rare earth ions produce interesting fluorescence spectra on laser excitation depending on the type of ordered or disordered (solid) host matrix. These fluorescence spectra, depending on RE concentration and quenching effects, can be intense and may consist of either narrow-band (or line) emissions or broad-band spectra covering a wide spectral range. These spectra, acquired at laser wavelengths from the ultraviolet (UV) to the near-infrared (NIR), provide a practical means for the calibration of Raman instrumentation for both Raman frequency and intensity.
Relationship between TEM Microstructures of Al Films and Reflectance in Color Display Tubes
Authors: Lee S J , Hwang ES , Dolukhanyan T , Sung C M
Published: July 2020

Al films have been deposited on the inside of the Color Display Tube (CDT) panel on which black matrix carbon and RGB phosphors were coated to improve brightness with the prevention of voltage down and less ion impact to phosphors. The characteristics of Al films have a close relationship with the deposition variables such as base pressure and deposition rate causing changes in Al film microstructures and differences in the reflectance. It is generally known that the reflectance is affected by the thickness, grain size, and surface roughness of the Al film: The grain size of the Al film tends to decrease when base pressure is poor due to the presence of residual gas. The reflectance of Al alloys was reported to be increased with the larger grain size.

The purpose of this study is to understand the relationship between the reflectance and the microstructures of Al films as a function of base pressure in a CDT manufacturing to optimize deposition conditions for improved reflection properties.
Solidification Behavior of a 319 Aluminum Alloy
Authors: Donlon W T , Godlewski LA , Zindel J W
Published: July 2020

319 aluminum (6.5-8.5% Si, 3.0-4.0%Cu, 0.2-0.45%Mg, 0.8%max.Fe, 0.5%max.Mn) is utilized by the automobile industry for engine block and cylinder head applications. Detailed understanding of the solidification behavior is critical to optimizing the “as-cast” microstructure and the physical properties of this alloy. Samples were generated by allowing a 50 gram sample of molten alloy to partially solidify at a slow cooling rate (0.34 °C/sec). During cooling, the temperature of the alloy was monitored by a thermocouple in the center of the sample to generate a cooling curve (Fig. 1). At various locations along this cooling curve the normal cooling was interrupted by plunging the cup into an iced- brine quench. In addition to optical and SEM examination, detailed TEM analysis was performed on three quenched samples as well as one sample allowed to cool uninterrupted to room temperature. TEM sample preparation consisted of standard grinding and dimpling procedures followed by ion milling at liquid nitrogen temperature using a gun voltage of 4keV.
Nucleation of the α / γ Massive Phase Transformation in Titanium- 48at% Aluminum
Authors: Wittig JE , Hofmeister WH
Published: July 2020

Massive phase transformations exhibit a change in crystal structure without a change in composition. Nucleation and growth of this difTUsionless transformation has been studied in numerous systems including Cu-Zn, Ag-Zn and Ag-Al. There is general agreement that heterogeneous grain boundary nucleation occurs with a rational orientation relationship with at least one of the parent grains, although growth of the massive product can often occur with a partially coherent interface.

The typical Ti-48at%Al microstructure is a lamellar structure of hexagonal α2 (DO19 superlattice) and the ordered tetragonal γ phase (Ll0 with c/a = 1.01). Water or ice brine quenching of the high temperature disordered α phase results in a partial massive transformation of a into γ. Electron beam melting has been used to further suppress the equilibrium transformations. However, the current study uses rapid solidification by electromagnetic levitation and twin anvil splat quenching (cooling rates > 106 K/s) to capture earlier stages of the transformation.
Characterization of Corrosion Scales on Fe-13Cr Stainless Steel
Authors: Subramanian S , Ling S , Ramanarayanan T A
Published: July 2020

Fe-13Cr stainless steel is a corrosion resistant alloy (CRA) that is widely used in oil and gas production for equipment such as tubes in wells. The high temperature, high CO2 and H2S partial pressures of typical production environments and the significant amounts of Cl- containing water that is produced along with the hydrocarbons affects the corrosion processes. Fe-13Cr is used for tubes since it exhibits passivity and low corrosion rates in production environments. But, during production operations, it is often necessary to pump strong acids into the underground rock formation through the tubes to stimulate the field and increase productivity. This is done in order to dissolve deposits that clog pores in the rock formation, thus improving permeability and facilitating the flow of hydrocarbons. This is expected to significantly degrade the passivity and lead to increased corrosion. Therefore, there is a concern about the corrosion rate during the operation and the rate at which the alloy repassivates when production is resumed.
Statics and Dynamics of “Charged” Interfaces in Electroceramics
Authors: Lin Xiwei , Murray Conal , Dravid Vinayak P
Published: July 2020

A large number of electroceramics derive their technologically useful and scientifically appealing properties via electrically active (charged) interfaces.[l] These interfaces can be simple grain boundaries in, for example, varistors, to complicated domain configuration in ferroelectric thin films. Several common issues relate to virtually all electrically active interfaces. The electrical activity of such interfaces is usually a consequence of trapping of charged electronic and/or ionic defects. Such trapping leads to compensating charge of opposite sign across the interfaces, viz. space-charge region. Collectively, they influence and often dominate a wide variety of phenomena, ranging from formation of Schottky barriers to impedence to domain boundary motion.

While bulk measurements, either electrical (e.g. P-E, C-V, I-V), optical (e.g. Raman) or resonance (e.g. EPR) have contributed significantly to the understanding of charged interfaces, there are very few direct observations of electrical activity of interfaces at a length-scale which is essential (i.e. 1- 10 nm).
Interpreting Uranyl Mineral Diffraction Patterns
Authors: Buck Edgar C
Published: July 2020

Secondary phases that form during the corrosion of nuclear waste forms may influence both the rate of waste form dissolution and the release of radionuclides [1]. The identification of these phases is critical in developing models for the corrosion behavior of nuclear waste forms. In particular, the secondary uranyl (VI) minerals that form during waste form alteration may control uranium solubility and release of radionuclides incorporated into these phases [2].

The U6+ cation in uranyl minerals is almost always present as a linear (UO2)2+ ion [3]. This uranyl (Ur) ion is coordinated by four, five, or six anions (ϕ) in the equatorial plane resulting in the formation of square (Urϕ4), pentagonal (Urϕ5), and hexagonal (Urϕ6) bipyramids, respectively [3]. These bipyramid polyhedra may polymerize to form complex infinite sheet structures. The linking of Urϕ5 is observed in a number of uranyl minerals formed during waste glass and spent fuel corrosion [2,4], such as weeksite [Na,K(UO2)2(Si205)3*4H2O] and β-uranophane [Ca[(UO2)(SiO3OH)]2*5H2O].
Microstructural Characterization of Carbon Fiber-Reinforced Laminated Matrix Composites of Silicon Carbide and Carbon
Authors: Appiah K A , Wang Z L , Lackey W J
Published: July 2020

Silicon carbide composites are known for high-temperature strength retention, creep resistance, high elastic modulus and light weight. Laminated matrix composites (LMC's) with a matrix of alternating layers of silicon carbide (SiC) and carbon (C) with carbon fiber reinforcements possess added toughness in addition to the desirable properties of SiC composites mentioned above. The improved toughness results from both the laminated matrix, which offers a tortuous path to crack propagation, and the energy expended in fiber debonding during fracture. Microstructural analyses of LMC's are necessary to help the processing effort to achieve structures with the desired properties. In this work, a preliminary examination of the microstructure of the laminated matrix composite is undertaken using TEM.

Specimens for TEM examination were prepared by cutting slices from a bulk sample of ∼ 1 mm thickness with a low-speed diamond saw. The slices were then ground to no less than 200 μm thickness to prevent the slices from breaking.
Characterization of Intergranular Phases in Tetragonal and Cubic Yttria-Stabilized Zirconia
Authors: Evans ND , Imamura PH , Bentley J , Mecartney ML
Published: July 2020

Achieving superplasticity in fine-grained ceramics is a potential method to lower energy costs associated with ceramic manufacturing via net shape forming. Superplasticity is intrinsic in 3-mol%- yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP), and can be enhanced by addition of glass to form intergranular phases which are thought to both limit grain growth and promote grain boundary sliding during processing (sintering and hot isostatic pressing). This permits processing at lower temperatures. However, superplasticity has not been observed in 8-mol%-yttria-stabilized cubic zirconia (8Y-CSZ), ostensibly due to its larger grain size and high grain growth rates.3,4 As part of a larger study, high-spatial-resolution energy-dispersive X-ray spectrometry (EDS) has been performed on 3Y-TZP and 8Y-CSZ specimens doped with various glassy phases to characterize intergranular compositions.

Zirconia powders were mixed with glass to produce specimens having either 1 wt % lithiumaluminum- silicate, 1 wt % barium-silicate, or 1 wt % borosilicate. Some specimens were prepared without added glass.
Polytypic Constraints for Solid-State Layer Silicate Transformation Mechanisms Via Atomic-Resolution Transmission Electron Microscopy
Authors: J.F. Banfield , T. Kogure
Published: July 2020

Layer silicates are important and abundant minerals. Polytypic details can be determined directly from atomic-resolution images recorded down [010] of layer silicates such as chlorite (Fig. 1), serpentine, and micas using a transmission electron microscope with a point resolution of ∼ 0.2 nm. For chlorite, this involves determination of whether octahedral slants in the brucite-like interlayers and octahedral sheet of the tetrahedral - octahedral-tetrahedral (TOT) layers are the same or opposed, the (3 angle, and how the octahedral cations in the brucite-like interlayer are positioned relative to the tetrahedral cations in the TOT layer (Fig. 1). Images must be recorded from the thinnest areas in order to distinguish slant of the brucite-like interlayer (composition dependent, but always < 0.7 nm sample thickness; 1). Polytype analysis is aided significantly by rotational filtering of images from thin areas to remove the amorphous contribution (2). All six of the common, semi-randomly stacked chlorite polytypes can be distinguished (1).