bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Microspectroscopy: Where are we and where are we going ?
Authors: Reffner John A. 
Published: June 2020

Molecular microspectroscopy is the application of infrared or Raman spectroscopy, combined with light microscopy, for chemical analysis on the microscopic scale. For over a decade infrared microspectroscopy (IMS) has been an expanding technology both scientifically and commercially. Micro-Raman spectroscopy has a long history of scientific accomplishments with limited commercial success. Both of these techniques give spectral data that can be related to the bonding, crystalline state, isotopic content and molecular orientation of a material, but not its elemental composition. In this regards, molecular microspectroscopy compliments the elemental analyses performed with electron microscopes using x-ray emission spectroscopy. Resolving molecular chemistry of microscopic domains is the essence of molecular microspectroscopy.Raman spectroscopy is experiencing renewed interest because of several advances in optics and photonics. Near-infrared lasers combined with Fourier transform spectrometers greatly reduced fluorescence interference, making Raman spectroscopy practical for many samples. The development of filters with high rejection of the Rayleigh scattered radiation simplifies the optical design of Raman systems. These filters are playing an important role in micro-Raman. CCD and CID detector technology, lasers, acusto-optical tuned filters (AOTF), liquid-crystal tuned filters (LCTF) and imaging spectrometers are contributing to a proliferation of new micro-Raman systems.
Applications of Wide Field Fluorescence and Confocal Reflectance Microscopy to Bone and Cartilage Studies
Authors: Chestnut M.H. , Ibbotson K.J. , Taiwo Y.O. , Dufresne T.E. , Amburgey J.S. , Ebetino F.H. , Finch J.L. 
Published: June 2020

Bisphosphonate Uptake by Living CellsBisphosphonates are drugs which inhibit bone resorption and are being pursued as therapies for osteoporosis. The molecular mechanisms by which bisphosphonates exert their biological effects are still unclear. It is generally assumed that uptake of these highly polar molecules by cells is very limited. In order to determine whether bisphosphonates are internalized and therefore may act intracellularly, we have examined the extent of their cellular uptake using a fluorescent naphthalene-dicarboxaldehyde (NDA) derivative of alendronate (ALN).The distribution of NDA-ALN was examined in Ros 17/2.8 osteoblast-like osteosarcoma cells and freshly isolated neonatal rat osteoclasts by fluorescence microscopy following 0.5-24 hours of treatment in vitro. Data were collected using a Nikon Diaphot 300 equipped with a 60x planapochromat objective and high N.A. DIC optics. Images captured using a Photometries PXL camera were processed using UIC Metamorph software.Uptake of the bisphosphonate into the cells was rapid and could be detected after 30 minutes of treatment in cells exposed to an external concentration of 10–5M NDA-ALN. Bisphosphonate appeared to accumulate over time within vacuolar, often perinuclear structures similar in appearance to secondary lysosomes (Figure 1). NDA-ALN was retained within cells after washing. These observations are consistent with the uptake of NDA-ALN proceeding via fluid-phase endocytosis. Uptake was greatly reduced when cells were incubated with the bisphosphonate at 20°C rather than 37°C. Freshly isolated osteoclasts also exhibited a noticeable amount of diffuse cytoplasmic staining (Figure 1), possibly indicating the presence of a second path of entry into the cell.
Analysis of Grain-Boundary Structures by Quantitative Hrtem
Authors: Nadarzinski K. , Kienzle O. , Ernst F. 
Published: June 2020

HRTEM (high-resolution transmission electron microscopy) constitutes a powerful technique to investigate the atomistic structure of grain boundaries. However, interpreting HRTEM images of grain boundaries in terms of “projected structure” may lead to errors: Near a boundary, the contrast patterns of atom columns may differ from the corresponding patterns in regions of unfaulted crystal. Even worse, dynamic diffraction and lens aberrations may displace the contrast patterns against the actual (projected) positions of the columns. Nevertheless, it is possible to interpret such images safely by comparing them with simulated images of structure models. This method becomes powerful if one compares experimental and simulated images not merely by visual inspection but quantitatively, by means of digital image processing.For a given HRTEM image of a grain boundary we iterate such quantitative image comparisons to perform an automatic structure refinement, which determines the structure that yields the best-matching simulated image to the experimental image (Fig. 1). While we can refine the positions of atom columns to any numerical precision, the coordinates only have a limited reliability. This arises because it is impossible to simulate HRTEM images perfectly – even if one knew the structure of the specimen. To quantify error limits for the column coordinates we explore how the simulated image of the refined structure changes with small displacements of the columns. It turns out that our method delivers the coordinates of atom columns with a precision in the order of 0.01 nm. The method also accounts for the damage that electron beam irradiation introduces in the specimen. By means of “beam damaging experiments” we estimate the maximum duration of irradiation to be allowed before damaging interferes with determining the structure at a given precision.
Determining Atomic Structure-Property Relationships at Grain Boundaries
Authors: Browning N. D. , Wallis D. J. , Nellist P. D. , Pennycook S. J. 
Published: June 2020

Atomic scale effects at grain boundaries are known to play a dominant role in controlling the bulk properties of many materials. However, a detailed understanding of this role is complicated by the tendency for boundaries to behave in a “non-ideal” manner, i.e. the boundary plane can change on the scale of a few nanometers, altering the number of vacancies and impurities and the presence of second phases. The crucial first step to engineering boundary properties is therefore the ability to observe these changes experimentally with both atomic resolution and sensitivity. Such a capability is provided by the combination of Z-contrast imaging and electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM).The Z-contrast technique generates an incoherent, atomic resolution structural image of a grain boundary which can be used to position the electron probe with atomic precision for spectroscopy. As the spectrum has nearly the same resolution as the image for core-losses >100eV, this arrangement has the unique advantage of allowing compositional fluctuations to be correlated directly with structural features in the boundary plane. Furthermore, multiple-scattering (MS) analysis can be utilized to extract 3- dimensional structural information from the spectrum. MS techniques consider the fine-structure of the spectrum to arise from interference effects occurring when a photoelectron created during the energy loss process is reflected from neighboring atoms. The real-space clusters used in this methodology allow the flexibility to determine whether the contributions to the spectrum arise from single or multiple scattering paths and from which atomic neighbors they originate. This allows the different structural relaxations that occur at boundaries, i.e. vacancies or structural disorder, to be distinguished from the spectrum.
EELS Measurement of the Local Electronic Structure of Copper Atoms Segregated to Aluminum Grain Boundaries
Authors: Splinter S.J. , Bruley J. , Batson P.E. , Smith D.A. , Rosenberg R. 
Published: June 2020

It has long been known that the addition of Cu to Al interconnects improves the resistance to electromigration failure. It is generally accepted that this improvement is the result of Cu segregation to Al grain boundaries. The exact mechanism by which segregated Cu increases service lifetime is not understood, although it has been suggested that the formation of thin layers of θ-CuA12 (or some metastable substoichiometric precursor, θ’ or θ”) at the boundaries may be necessary. This paper reports measurements of the local electronic structure of Cu atoms segregated to Al grain boundaries using spatially resolved EELS in a UHV STEM. It is shown that segregated Cu exists in a chemical environment similar to that of Cu atoms in bulk θ-phase precipitates.Films of 100 nm thickness and nominal composition Al-2.5wt%Cu were deposited by sputtering from alloy targets onto NaCl substrates. The samples were solution heat treated at 748K for 30 min and aged at 523K for 4 h to promote equilibrium grain boundary segregation. EELS measurements were made using a Gatan 666 PEELS spectrometer interfaced to a VG HB501 STEM operating at 100 keV. The probe size was estimated to be 1 nm FWHM. Grain boundaries with the narrowest projected
width were chosen for analysis. EDX measurements of Cu segregation were made using a VG HB603 STEM.
AFM as a Tool for Studying Ceramic Surfaces
Authors: Heffelfinger Jason R. , Bench Michael W. , Johnson Matthew T. , Carter C. Barry 
Published: June 2020

Atomic-force microscopy (AFM), which is a relatively new technique, has found an invaluable niche in the imaging of insulating surfaces. AFM allows for analysis of topographical details at the atomic level with minimum sample preparation. Unlike scanning electron microscopy (SEM), AFM sample preparation requires no conductive coatings that may cover small surface features. The real power of the AFM lies in its ability to directly measure the heights of various surface features such as surface steps and particulates that measure as small as a few tenths of a nanometer in size. This technique does have limitations, and image artifacts, such as broadening of surface structures and ghost images of the tip, arise from the finite size and shape of the contacting probe. In the present investigation, AFM is used to characterize ceramic surfaces in a variety of experiments which range from surface faceting to solid-state reaction studies.AFM studies were performed on a multi-mode, Nanoscope III (Digital Instruments, Santa Barbara, CA) using microfabricated Si3N4 cantilevers. The cantilevers were Cr coated to avoid charging effects between the tip and specimen. All images were recorded in air with a nominal applied force of 10-15 nN. AFM samples which were used to study the effect of surface faceting were prepared from polished single crystals. To remove surface damage and create a faceted surface, these sample were annealed at 1400°C for different amounts of time in air. Special precautions were taken to minimize the exposure of the surfaces to any contamination from the furnace environment during annealing. Solid-state reactions experiments were performed by reacting a cleaved {001} MgO surface with a Fe2O3 powder for 6 hours at 1450°C in air.
The Variation of (1 0-1 0) Surfaces of Sapphire between Different Annealing Time and Temperatures[1] Using Reflection Electron Microscopy (REM) [1]
Authors: HSU Tung , SU Guo Hung , Kim Yootaek 
Published: June 2020

The (1 0-1 0) surface of sapphire (α-Al2O3), one of the prismatic surfaces, is a high energy surface [2,3]- Therefore, upon annealing, this surface breaks down into two sets of facets of lower energies. The two facets have been indexed and have been found to start developing along defects of the polished (1 0-1 0) surfaces [4, 5]. The goal of this study was to observe the very beginning of the development of these facets under various temperatures. The technique employed was reflection electron microscopy (REM) [6, 7] which is very sensitive to irregularity on crystal surfaces and has been successfully applied to the study of other low index surfaces of sapphire [8-10].The sapphire specimens used in this experimental were manufactured with the edge-defined film -fed growth (EFG) method by Saphikon, Inc., Milford, NH. Specimen orientation was confirmed with the reflection Laue camera. The specimens were polished by hand to 0.1 µm. Annealing was done in a Lindberg tube furnace, with a heating rate of 200°C/hr and maximum temperatures of 1000°C to 1400°C maintained for 0.1 hr to 40 hr.
Microscopy Outreach Through Shared Technology
Authors: Walsh Rosemary A. 
Published: June 2020

Educational Outreach at PSU’s EM Facility for the Life Sciences evolved from the consolidation of multi-user laboratories and a growing demand for hands- on laboratory experiences requested by undergraduates, middle and highschool students and their teachers in central Pennsylvania. The EM lab is one of five such shared technology facilities which primarily provide university researchers with services and training.The development of educational outreach programs grew from early work on extension projects with faculty and graduate students in the College for Agricultural Sciences. That experience and a new climate of cooperation permitted our laboratory to promote problem-based learning in funded programs such as undergraduate reasearch (independent study /honors projects) and summer institutes for pre-college students in Biology (Howard Hughes Institute) and Agricultural Sciences (Pennsylvania Governor’s School, PGSAS).
Outreach Opportunities Using the Instructional SEM at Iowa State University
Authors: Chumbley L. S. , Meyer M. , Fredrickson K. , Laabs F.C. 
Published: June 2020

The development of a scanning electron microscope (SEM) suitable for instructional purposes has created a large number of outreach opportunities for the Materials Science and Engineering (MSE) Department at Iowa State University. Several collaborative efforts are presently underway with local schools and the Department of Curriculum and Instruction (C&I) at ISU to bring SEM technology into the classroom in a near live-time, interactive manner. The SEM laboratory is shown in Figure 1.Interactions between the laboratory and the classroom use inexpensive digital cameras and shareware called CU-SeeMe, Figure 2. Developed by Cornell University and available over the internet, CUSeeMe provides inexpensive video conferencing capabilities. The software allows video and audio signals from Quikcam™ cameras to be sent and received between computers. A reflector site has been established in the MSE department that allows eight different computers to be interconnected simultaneously. This arrangement allows us to demonstrate SEM principles in the classroom. An Apple Macintosh has been configured to allow the SEM image to be seen using CU-SeeMe.
Total-Reflection X-Ray Fluorescence Spectrometry (TXRF): Application to Elemental Profiles on Trace Evidence and Microsamples
Authors: Kubic MS, JD Thomas A. , Buscaglia MS JoAnn , Reus Ulrich 
Published: June 2020

Total-Reflection X-ray Fluorescence spectrometry has been available as commercial instrumentation for the past few years. Since that time investigations and research has been conducted on the application of the technique particularly to problems involving micro samples such as in conservation and forensic analysis.Elemental characterization of paint pigments, glass samples, textile fibers and liquid inclusions have been performed.The EXTRA IIA TXRF spectrometer has inherent potential for the microanalysis. This instrumentation allows for simultaneous multi-element analysis for elements Phosphorus to Uranium with instrument detection levels (IDLs) less than or equal to 10 picograms for 50 of these elements.Qualitative and semi-quantitative screening are possible with little sample preparation, while dissolved samples result in improved accuracy and precision with a dynamic range of five orders of magnitude without multiple dilutions.This paper briefly reviews the principal and theory of TXRF, the operation of this instrument and its advantages over other quantitative elemental analysis techniques for these types of samples. Data demonstrating the comparable results obtained with the EXTRA IIA to that of ICP, AA, and NAA methods on samples supplied as proficiency tests will be presented. No difference in the quantitative results was exhibited between the reference and test data at a 95% confidence level.
Corrections for Several Factors that Limit Quantitative Analysis Of 3-D Data Sets Collected using Scanning-Laser Confocal Microscopy
Authors: Kayali S. , Ancin H. , Roysam B. , Szarowski D.H. , Shain W. , Turner J.N. 
Published: June 2020

The confocal microscope collects high contrast 2-D images at different depths from thick (≥100 μm) tissues samples, thus providing data for quantitative measurements of 3-D objects. There are several factors that may limit quanititative analysis including photobleaching of fluors, attenuation of measured signal, mismatch in the various refractive indeces of the sample, and the width of the point spread function. We have addressed the first three of these limitations by using acriflavine-stained 100- [im thick sections of rat hippocampus and our 3-D automated analysis software. The laminar structure of the hippocampus provides tissue sections with areas of high and low nuclear density (pyramidal and extra-pyradmidal cell regions, respectively). Corrections for these limitations were made to samples from rat testes where developing spermatogonia provide nuclei of different DNA content.The contribution of photobleaching to signal degradation was determined by collecting multiple 3-D images (z-series) of the same field. Twenty-one images of 50 planes each were collected (total scans= 1050).
Fundamental parameters for microanalysis
Authors: Joy David C 
Published: June 2020

In order to perform quantitative X-ray microanalysis many parameters, representing the various stages of Xray generation and transport through the specimen at the chosen experimental conditions, must be known for all of the elements that might be encountered. Although ideally quantification is done by reference to standards so that only the functional variation of these parameters is required, in current practice it is increasingly necessary to work in situations where standardization is impossible and consequently where absolute magnitudes must be known. The quality and quantity of data that is now available varies widely.Ionization cross sectionsAlthough the amount of experimental data is limited, particularly in the energy range between 1 and 20keV, a critical assessment has concluded that for K-shell excitations both the magnitude of the cross-section σ and its variation with energy are adequately well known for overvoltages greater than about 2. For L- and M-shell excitations, however, and in all cases when the operational overvoltage is less than 2, the situation is much less satisfactory.
EDS x-ray microcalorimeters with 13 eV energy resolution
Authors: Wollman D. A. , Hilton G. C. , Irwin K. D. , Martinis J. M. 
Published: June 2020

Although Si- and Ge-based Energy Dispersive Spectroscopy (EDS) detectors are by far the most commonly used x-ray spectrometers for microanalysis, they are limited by energy resolutions on the order of 100 eV. This low energy resolution is insufficient to clearly resolve many peak overlaps between Kα x-ray lines of different elements. In addition, many L and M lines of heavier elements fall in the 100 eV to 2 keV energy range, making it difficult in complicated spectra to identify and quantify the presence of technologically important lighter elements. Higher energy resolution and good count rates are necessary to provide improved limits of detectability.We are developing a cryogenic x-ray microcalorimeter with significantly improved energy resolution and a count rate and detector area suitable for EDS microanalysis. In a calorimeter, the energy of an x-ray is converted to heat, and a measurement of the temperature rise of the detector gives the deposited photon energy. Our microcalorimeter detector consists of a normal-metal x-ray absorber which is in thermal and electrical contact with a superconducting transition-edge sensor (TES).
Lead-phase determination and demonstration of contaminated soil remediation mechanism by scanning electron microscopy and characteristic x-ray imaging
Authors: Vander Wood T. B. 
Published: June 2020

The utility of microscopy and microanalysis in the study of contaminated atmospheres is well established. The particulate nature of soils suggests that these methods would be equally useful in the study of contaminated soils and similar materials; however, the focus on bulk contaminant concentrations, solution chemistry and leachability has obscured the role of microanalysis in elucidating the chemistry of contamination and in guiding remediation methods.A case in point is the study of lead contaminated soils and possible remediation strategies. Ma, et al, recognized that reaction of lead with hydroxyapatite provided a possible remediation method for lead contaminated soils by precipitation of hydroxypyromorphite [Pb10(PO4)6(OH)2], proposing that the mechanism of lead immobilization in contaminated soils is congruent alteration, that is, dissolution of hydroxyapatite [Ca10(PO4)6(OH)2]to give phosphate ion in solution, followed by precipitation of dissolved lead ion as hydroxypyromorphite.
Atomic-resolution eels for composition and 3-D coordination determination at interfaces and defects
Authors: Browning N. D. , Wallis D. J. , Sivananthan S. , Nellist P. D. , Pennycook S. J. 
Published: June 2020

Materials properties associated with interfaces and defects are dominated by atomic scale fluctuations in composition, structure and bonding. Although electron energy loss spectroscopy (EELS) provides a powerful tool to probe these features, low signal, lens aberrations, image coherence and specimen drift preclude the use of spectrum imaging and energy filtered imaging for these high-resolution problems. However, by utilizing Z-contrast imaging in conjunction with EELS in the scanning transmission electron microscope (STEM), these limitations are largely overcome and EELS appears capable of providing fudamental 3-D characterization of defect and interface structures with atomic resolution and sensitivity.The main premise in utilizing these combined techniques is that the properties of defects and interfaces must be associated with structural differences relative to the bulk. If those structural differences can be located, then it is only necessary to perform spectroscopy in their vicinity to understand the structure property relationship. For crystalline materials in zone-axis orientations, the Z-contrast image provides this atomic resolution structural map. As this direct image is generated with only the high-angle scattering, it can be used to position the electron probe with atomic precision and does not interfere with the low-angle scattering for spectroscopy.
Plug-in scripts for EFTEM automation
Authors: Evans N. D. , Kundmann M. K. 
Published: June 2020

Post-column energy-filtered transmission electron microscopy (EFTEM) is inherently challenging as it requires the researcher to setup, align, and control both the microscope and the energy-filter. The software behind an EFTEM system is therefore critical to efficient, day-to-day application of this technique. This is particularly the case in a multiple-user environment such as at the Shared Research Equipment (SHaRE) User Facility at Oak Ridge National Laboratory. Here, visiting researchers, who may oe unfamiliar with the details of EFTEM, need to accomplish as much as possible in a relatively short period of time.We describe here our work in extending the base software of a commercially available EFTEM system in order to automate and streamline particular EFTEM tasks. The EFTEM system used is a Philips CM30 fitted with a Gatan Imaging Filter (GIF). The base software supplied with this system consists primarily of two Macintosh programs and a collection of add-ons (plug-ins) which provide instrument control, imaging, and data analysis facilities needed to perform EFTEM.