Energy-selective SESD imaging utilizing a CMA. [Scanning Electron Stimulated Desorption with Cylindrical Mirror Analyzer

NASA Technical Reports Server (NTRS)

Larson, L. A.; Soria, F.; Poppa, H.

1980-01-01

A particularly simple conversion of a scanning Auger system for ESD ion energy distributions and scanning ESD has been developed. This approach combines the advantages of the small spot-size electron guns and mapping systems developed for SAM with the capability of ESD for the detection of hydrogen. Our intended use for the device is detection and mapping of surface concentrations of hydrogen on metals. The characteristics of SESD are illustrated with the preliminary results of an investigation into the ESD properties of hydrogenic adsorbates on Nb. It is shown that the ESDIED exhibit distinct differences indicative of the surface preparation, and that the ESD ion angular distributions have an effect on the observed contrast relationships in SESD.

Environmental scanning electron microscopy gold immunolabeling in cell biology.

PubMed

Rosso, Francesco; Papale, Ferdinando; Barbarisi, Alfonso

2013-01-01

Immunogold labeling (IGL) technique has been utilized by many authors in combination with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to obtain the identification/localization of receptors and antigens, both in cells and tissues. Environmental scanning electron microscopy (ESEM) represents an important tool in biomedical research, since it does not require any severe processing of the sample, lowering the risk of generating artifacts and interfere with the IGL procedure. The absence of metal coating could yield further advantages for our purpose as the labeling detection is based on the atomic number difference between nanogold spheres and the biological material. Using the gaseous secondary electron detector, compositional contrast is easily revealed by the backscattered electron component of the signal. In spite of this fact, only few published papers present a combination of ESEM and IGL. Hereby we present our method, optimized to improve the intensity and the specificity of the labeling signal, in order to obtain a semiquantitative evaluation of the labeling signal.In particular, we used a combination of IGL and ESEM to detect the presence of a protein on the cell surface. To achieve this purpose, we chose as an experimental system 3T3 Swiss albino mouse fibroblasts and galectin-3.

Zeiss ΣIGMA VP-FE-SEM User Guide

EPA Science Inventory

User guide for analyzing carbon based nanomaterials on a Zeiss Sigma microscope. The guide includes helpful steps for sample preparation and loading. Specific topics utilizing the scanning electron microscope are instrumentation startup and imagining. A variety of detectors in...

Solid state optical microscope

DOEpatents

Young, I.T.

1983-08-09

A solid state optical microscope wherein wide-field and high-resolution images of an object are produced at a rapid rate by utilizing conventional optics with a charge-coupled photodiode array. A galvanometer scanning mirror, for scanning in one of two orthogonal directions is provided, while the charge-coupled photodiode array scans in the other orthogonal direction. Illumination light from the object is incident upon the photodiodes, creating packets of electrons (signals) which are representative of the illuminated object. The signals are then processed, stored in a memory, and finally displayed as a video signal. 2 figs.

Solid state optical microscope

DOEpatents

Young, Ian T.

1983-01-01

A solid state optical microscope wherein wide-field and high-resolution images of an object are produced at a rapid rate by utilizing conventional optics with a charge-coupled photodiode array. A galvanometer scanning mirror, for scanning in one of two orthogonal directions is provided, while the charge-coupled photodiode array scans in the other orthogonal direction. Illumination light from the object is incident upon the photodiodes, creating packets of electrons (signals) which are representative of the illuminated object. The signals are then processed, stored in a memory, and finally displayed as a video signal.

Towards the low-dose characterization of beam sensitive nanostructures via implementation of sparse image acquisition in scanning transmission electron microscopy

NASA Astrophysics Data System (ADS)

Hwang, Sunghwan; Han, Chang Wan; Venkatakrishnan, Singanallur V.; Bouman, Charles A.; Ortalan, Volkan

2017-04-01

Scanning transmission electron microscopy (STEM) has been successfully utilized to investigate atomic structure and chemistry of materials with atomic resolution. However, STEM’s focused electron probe with a high current density causes the electron beam damages including radiolysis and knock-on damage when the focused probe is exposed onto the electron-beam sensitive materials. Therefore, it is highly desirable to decrease the electron dose used in STEM for the investigation of biological/organic molecules, soft materials and nanomaterials in general. With the recent emergence of novel sparse signal processing theories, such as compressive sensing and model-based iterative reconstruction, possibilities of operating STEM under a sparse acquisition scheme to reduce the electron dose have been opened up. In this paper, we report our recent approach to implement a sparse acquisition in STEM mode executed by a random sparse-scan and a signal processing algorithm called model-based iterative reconstruction (MBIR). In this method, a small portion, such as 5% of randomly chosen unit sampling areas (i.e. electron probe positions), which corresponds to pixels of a STEM image, within the region of interest (ROI) of the specimen are scanned with an electron probe to obtain a sparse image. Sparse images are then reconstructed using the MBIR inpainting algorithm to produce an image of the specimen at the original resolution that is consistent with an image obtained using conventional scanning methods. Experimental results for down to 5% sampling show consistency with the full STEM image acquired by the conventional scanning method. Although, practical limitations of the conventional STEM instruments, such as internal delays of the STEM control electronics and the continuous electron gun emission, currently hinder to achieve the full potential of the sparse acquisition STEM in realizing the low dose imaging condition required for the investigation of beam-sensitive materials, the results obtained in our experiments demonstrate the sparse acquisition STEM imaging is potentially capable of reducing the electron dose by at least 20 times expanding the frontiers of our characterization capabilities for investigation of biological/organic molecules, polymers, soft materials and nanostructures in general.

Unveiling the Mysteries of Mars with a Miniaturized Variable Pressure Scanning Electron Microscope (MVP-SEM)

NASA Technical Reports Server (NTRS)

Edmunson, J.; Gaskin, J. A.; Doloboff, I. J.

2017-01-01

Development of a miniaturized scanning electron microscope that will utilize the martian atmosphere to dissipate charge during analysis continues. This instrument is expected to be used on a future rover or lander to answer fundamental Mars science questions. To identify the most important questions, a survey was taken at the 47th Lunar and Planetary Science Conference (LPSC). From the gathered information initial topics were identified for a SEM on the martian surface. These priorities are identified and discussed below. Additionally, a concept of operations is provided with the goal of maximizing the science obtained with the minimum amount of communication with the instrument.

Notes on Citrullius spp. and Acanthosicyos naudinianus

USDA-ARS?s Scientific Manuscript database

Scanning electron and light microscopy were utilized to examine pollen of the currently recognized species (and forms) within the genus Citrullus (Cucurbitaceae). Materials examined included: C. lanatus (Thunb.) Matsum. & Nakai including the citron (C. amarus Schrad.) and egusi (C. lanatus subsp. mu...

Tools for a Document Image Utility.

ERIC Educational Resources Information Center

Krishnamoorthy, M.; And Others

1993-01-01

Describes a project conducted at Rensselaer Polytechnic Institute (New York) that developed methods for automatically subdividing pages from technical journals into smaller semantic units for transmission, display, and further processing in an electronic environment. Topics discussed include optical scanning and image compression, digital image…

[application of the analytical transmission electron microscopy techniques for detection, identification and visualization of localization of nanoparticles of titanium and cerium oxides in mammalian cells].

PubMed

Shebanova, A S; Bogdanov, A G; Ismagulova, T T; Feofanov, A V; Semenyuk, P I; Muronets, V I; Erokhina, M V; Onishchenko, G E; Kirpichnikov, M P; Shaitan, K V

2014-01-01

This work represents the results of the study on applicability of the modern methods of analytical transmission electron microscopy for detection, identification and visualization of localization of nanoparticles of titanium and cerium oxides in A549 cell, human lung adenocarcinoma cell line. A comparative analysis of images of the nanoparticles in the cells obtained in the bright field mode of transmission electron microscopy, under dark-field scanning transmission electron microscopy and high-angle annular dark field scanning transmission electron was performed. For identification of nanoparticles in the cells the analytical techniques, energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy, were compared when used in the mode of obtaining energy spectrum from different particles and element mapping. It was shown that the method for electron tomography is applicable to confirm that nanoparticles are localized in the sample but not coated by contamination. The possibilities and fields of utilizing different techniques for analytical transmission electron microscopy for detection, visualization and identification of nanoparticles in the biological samples are discussed.

Backside illuminated CMOS-TDI line scan sensor for space applications

NASA Astrophysics Data System (ADS)

Cohen, Omer; Ofer, Oren; Abramovich, Gil; Ben-Ari, Nimrod; Gershon, Gal; Brumer, Maya; Shay, Adi; Shamay, Yaron

2018-05-01

A multi-spectral backside illuminated Time Delayed Integration Radiation Hardened line scan sensor utilizing CMOS technology was designed for continuous scanning Low Earth Orbit small satellite applications. The sensor comprises a single silicon chip with 4 independent arrays of pixels where each array is arranged in 2600 columns with 64 TDI levels. A multispectral optical filter whose spectral responses per array are adjustable per system requirement is assembled at the package level. A custom 4T Pixel design provides the required readout speed, low-noise, very low dark current, and high conversion gains. A 2-phase internally controlled exposure mechanism improves the sensor's dynamic MTF. The sensor high level of integration includes on-chip 12 bit per pixel analog to digital converters, on-chip controller, and CMOS compatible voltage levels. Thus, the power consumption and the weight of the supporting electronics are reduced, and a simple electrical interface is provided. An adjustable gain provides a Full Well Capacity ranging from 150,000 electrons up to 500,000 electrons per column and an overall readout noise per column of less than 120 electrons. The imager supports line rates ranging from 50 to 10,000 lines/sec, with power consumption of less than 0.5W per array. Thus, the sensor is characterized by a high pixel rate, a high dynamic range and a very low power. To meet a Latch-up free requirement RadHard architecture and design rules were utilized. In this paper recent electrical and electro-optical measurements of the sensor's Flight Models will be presented for the first time.

Three-Dimensional Optical Coherence Tomography

NASA Technical Reports Server (NTRS)

Gutin, Mikhail; Wang, Xu-Ming; Gutin, Olga

2009-01-01

Three-dimensional (3D) optical coherence tomography (OCT) is an advanced method of noninvasive infrared imaging of tissues in depth. Heretofore, commercial OCT systems for 3D imaging have been designed principally for external ophthalmological examination. As explained below, such systems have been based on a one-dimensional OCT principle, and in the operation of such a system, 3D imaging is accomplished partly by means of a combination of electronic scanning along the optical (Z) axis and mechanical scanning along the two axes (X and Y) orthogonal to the optical axis. In 3D OCT, 3D imaging involves a form of electronic scanning (without mechanical scanning) along all three axes. Consequently, the need for mechanical adjustment is minimal and the mechanism used to position the OCT probe can be correspondingly more compact. A 3D OCT system also includes a probe of improved design and utilizes advanced signal- processing techniques. Improvements in performance over prior OCT systems include finer resolution, greater speed, and greater depth of field.

Notes on Citrullus spp.: Pollen morphology, C values, and interspecific hybridization

USDA-ARS?s Scientific Manuscript database

Scanning electron and light microscopy were utilized to examine pollen of the currently recognized species (and forms) within the genus Citrullus (Cucurbitaceae). Materials examined included: C. lanatus (Thunb.) Matsum. & Nakai including the citron (C. amarus Schrad.) and egusi (C. mucosospermus (Fu...

Resolution-enhanced Mapping Spectrometer

NASA Technical Reports Server (NTRS)

Kumer, J. B.; Aubrun, J. N.; Rosenberg, W. J.; Roche, A. E.

1993-01-01

A familiar mapping spectrometer implementation utilizes two dimensional detector arrays with spectral dispersion along one direction and spatial along the other. Spectral images are formed by spatially scanning across the scene (i.e., push-broom scanning). For imaging grating and prism spectrometers, the slit is perpendicular to the spatial scan direction. For spectrometers utilizing linearly variable focal-plane-mounted filters the spatial scan direction is perpendicular to the direction of spectral variation. These spectrometers share the common limitation that the number of spectral resolution elements is given by the number of pixels along the spectral (or dispersive) direction. Resolution enhancement by first passing the light input to the spectrometer through a scanned etalon or Michelson is discussed. Thus, while a detector element is scanned through a spatial resolution element of the scene, it is also temporally sampled. The analysis for all the pixels in the dispersive direction is addressed. Several specific examples are discussed. The alternate use of a Michelson for the same enhancement purpose is also discussed. Suitable for weight constrained deep space missions, hardware systems were developed including actuators, sensor, and electronics such that low-resolution etalons with performance required for implementation would weigh less than one pound.

Electronic reporting of all reference laboratory results: An important step toward a truly all-encompassing, integrated health record.

PubMed

Kratz, Alexander

2016-09-01

Results from reference laboratories are often not easily available in electronic health records. This article describes a multi-pronged, long-term approach that includes bringing send-out tests in-house, upgrading the laboratory information system, interfacing more send-out tests and more reference laboratories, utilizing the "miscellaneous assay" option offered by some reference laboratories, and scanning all remaining paper reports from reference laboratories for display in the electronic health record. This allowed all laboratory results obtained in association with a patient visit, whether performed in-house or at a reference laboratory, to be available in the integrated electronic health record. This was achieved without manual data entry of reference laboratory results, thereby avoiding the risk of transcription errors. A fully integrated electronic health record that contains all laboratory results can be achieved by maximizing the number of interfaced reference laboratory assays and making all non-interfaced results available as scanned documents. © The Author(s) 2015.

Microstructure alterations in beef intramuscular connective tissue caused by hydrodynamic pressure processing

USDA-ARS?s Scientific Manuscript database

Scanning electron microscopy (SEM) was utilized to evaluate microstructural changes in intramuscular connective tissue of beef semimembranosus muscle subjected to hydrodynamic pressure processing (HDP). Samples were HDP treated in a plastic container (HDP-PC) or a steel commercial unit (HDP-CU). C...

New Technique for Fabrication of Scanning Single-Electron Transistor Microscopy Tips

NASA Astrophysics Data System (ADS)

Goodwin, Eric; Tessmer, Stuart

Fabrication of glass tips for Scanning Single-Electron Transistor Microscopy (SSETM) can be expensive, time consuming, and inconsistent. Various techniques have been tried, with varying levels of success in regards to cost and reproducibility. The main requirement for SSETM tips is to have a sharp tip ending in a micron-scale flat face to allow for deposition of a quantum dot. Drawing inspiration from methods used to create tips from optical fibers for Near-Field Scanning Optical Microscopes, our group has come up with a quick and cost effective process for creating SSETM tips. By utilizing hydrofluoric acid to etch the tips and oleic acid to guide the etch profile, optical fiber tips with appropriate shaping can be rapidly prepared. Once etched, electric leads are thermally evaporated onto each side of the tip, while an aluminum quantum dot is evaporated onto the face. Preliminary results using various metals, oxide layers, and lead thicknesses have proven promising.

Progressive fracture of fiber composites

NASA Technical Reports Server (NTRS)

Irvin, T. B.; Ginty, C. A.

1983-01-01

Refined models and procedures are described for determining progressive composite fracture in graphite/epoxy angleplied laminates. Lewis Research Center capabilities are utilized including the Real Time Ultrasonic C Scan (RUSCAN) experimental facility and the Composite Durability Structural Analysis (CODSTRAN) computer code. The CODSTRAN computer code is used to predict the fracture progression based on composite mechanics, finite element stress analysis, and fracture criteria modules. The RUSCAN facility, CODSTRAN computer code, and scanning electron microscope are used to determine durability and identify failure mechanisms in graphite/epoxy composites.

Domain imaging in ferroelectric thin films via channeling-contrast backscattered electron microscopy

DOE PAGES

Ihlefeld, Jon F.; Michael, Joseph R.; McKenzie, Bonnie B.; ...

2016-09-16

We report that ferroelastic domain walls provide opportunities for deterministically controlling mechanical, optical, electrical, and thermal energy. Domain wall characterization in micro- and nanoscale systems, where their spacing may be of the order of 100 nm or less is presently limited to only a few techniques, such as piezoresponse force microscopy and transmission electron microscopy. These respective techniques cannot, however, independently characterize domain polarization orientation and domain wall motion in technologically relevant capacitor structures or in a non-destructive manner, thus presenting a limitation of their utility. In this work, we show how backscatter scanning electron microscopy utilizing channeling contrast yieldmore » can image the ferroelastic domain structure of ferroelectric films with domain wall spacing as narrow as 10 nm.« less

Tropical rain mapping radar on the Space Station

NASA Technical Reports Server (NTRS)

Im, Eastwood; Li, Fuk

1989-01-01

The conceptual design for a tropical rain mapping radar for flight on the manned Space Station is discussed. In this design the radar utilizes a narrow, dual-frequency (9.7 GHz and 24.1 GHz) beam, electronically scanned antenna to achieve high spatial (4 km) and vertical (250 m) resolutions and a relatively large (800 km) cross-track swath. An adaptive scan strategy will be used for better utilization of radar energy and dwell time. Such a system can detect precipitation at rates of up to 100 mm/hr with accuracies of roughly 15 percent. With the proposed space-time sampling strategy, the monthly averaged rainfall rate can be estimated to within 8 percent, which is essential for many climatological studies.

Datasets, Technologies and Products from the NASA/NOAA Electronic Theater 2002

NASA Technical Reports Server (NTRS)

Hasler, A. Fritz; Starr, David (Technical Monitor)

2001-01-01

An in depth look at the Earth Science datasets used in the Etheater Visualizations will be presented. This will include the satellite orbits, platforms, scan patterns, the size, temporal and spatial resolution, and compositing techniques used to obtain the datasets as well as the spectral bands utilized.

Diffusion, convection, and solidification in cw-mode free electron laser nitrided titanium

NASA Astrophysics Data System (ADS)

Höche, Daniel; Shinn, Michelle; Müller, Sven; Schaaf, Peter

2009-04-01

Titanium sheets were irradiated by free electron laser radiation in cw mode in pure nitrogen. Due to the interaction, nitrogen diffusion occurs and titanium nitride was synthesized in the tracks. Overlapping tracks have been utilized to create coatings in order to improve the tribological properties of the sheets. Caused by the local heating and the spatial dimension of the melt pool, convection effects were observed and related to the track properties. Stress, hardness, and nitrogen content were investigated with x-ray diffraction, nanoindention, and resonant nuclear reaction analysis. The measured results were correlated with the scan parameters, especially to the lateral track shift. Cross section micrographs were prepared and investigated by means of scanning electron microscopy. They show the solidification behavior, phase formation, and the nitrogen distribution. The experiments give an insight into the possibilities of materials processing using such a unique heat source.

Revealing the correlation between real-space structure and chiral magnetic order at the atomic scale

NASA Astrophysics Data System (ADS)

Hauptmann, Nadine; Dupé, Melanie; Hung, Tzu-Chao; Lemmens, Alexander K.; Wegner, Daniel; Dupé, Bertrand; Khajetoorians, Alexander A.

2018-03-01

We image simultaneously the geometric, the electronic, and the magnetic structures of a buckled iron bilayer film that exhibits chiral magnetic order. We achieve this by combining spin-polarized scanning tunneling microscopy and magnetic exchange force microscopy (SPEX) to independently characterize the geometric as well as the electronic and magnetic structures of nonflat surfaces. This new SPEX imaging technique reveals the geometric height corrugation of the reconstruction lines resulting from strong strain relaxation in the bilayer, enabling the decomposition of the real-space from the electronic structure at the atomic level and the correlation with the resultant spin-spiral ground state. By additionally utilizing adatom manipulation, we reveal the chiral magnetic ground state of portions of the unit cell that were not previously imaged with spin-polarized scanning tunneling microscopy alone. Using density functional theory, we investigate the structural and electronic properties of the reconstructed bilayer and identify the favorable stoichiometry regime in agreement with our experimental result.

Integrating Elemental Analysis and Chromatography Techniques by Analyzing Metal Oxide and Organic UV Absorbers in Commercial Sunscreens

ERIC Educational Resources Information Center

Quin~ones, Rosalynn; Bayline, Jennifer Logan; Polvani, Deborah A.; Neff, David; Westfall, Tamara D.; Hijazi, Abdullah

2016-01-01

A series of undergraduate laboratory experiments that utilize reversed-phase HPLC separation, inductively coupled plasma spectroscopy (ICP), and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) are described for the analysis of commercial sunscreens. The active ingredients of many sunscreen brands include zinc or titanium…

The Heinz Electronic Library Interactive On-line System (HELIOS): An Update.

ERIC Educational Resources Information Center

Galloway, Edward A.; Michalek, Gabrielle V.

1998-01-01

Describes a project at Carnegie Mellon University libraries to convert the congressional papers of the late Senator John Heinz to digital format and to create an online system to search and retrieve these papers. Highlights include scanning, optical character recognition, and a search engine utilizing natural language processing. (Author/LRW)

FIBER AND INTEGRATED OPTICS, LASER APPLICATIONS, AND OTHER PROBLEMS IN QUANTUM ELECTRONICS: Spectrometer based on injection lasers emitting near-infrared radiation

NASA Astrophysics Data System (ADS)

Avetisov, V. G.; Kosichkin, Yu V.; Malakhova, V. I.; Merkulov, A. V.; Nadezhdinskiĭ, A. I.; Paleĭ, S. L.; Khusnutdinov, A. N.; Yakubovich, S. D.

1989-04-01

A two-beam spectrometer utilizing injection lasers emitting in the near infrared was constructed. The spectrometer utilizes rapid scanning of the laser emission frequency followed by recording with an analog-digital converter. The spectrometer parameters are as follows: a spectral resolution of at least 2 × 10 -3 cm-1, a response time 50 ns, and a detectivity amounting to 0.0003% of the incident power carried by one pulse.

Current–Voltage Characterization of Individual As-Grown Nanowires Using a Scanning Tunneling Microscope

PubMed Central

2013-01-01

Utilizing semiconductor nanowires for (opto)electronics requires exact knowledge of their current–voltage properties. We report accurate on-top imaging and I–V characterization of individual as-grown nanowires, using a subnanometer resolution scanning tunneling microscope with no need for additional microscopy tools, thus allowing versatile application. We form Ohmic contacts to InP and InAs nanowires without any sample processing, followed by quantitative measurements of diameter dependent I–V properties with a very small spread in measured values compared to standard techniques. PMID:24059470

Current-voltage characterization of individual as-grown nanowires using a scanning tunneling microscope.

PubMed

Timm, Rainer; Persson, Olof; Engberg, David L J; Fian, Alexander; Webb, James L; Wallentin, Jesper; Jönsson, Andreas; Borgström, Magnus T; Samuelson, Lars; Mikkelsen, Anders

2013-11-13

Utilizing semiconductor nanowires for (opto)electronics requires exact knowledge of their current-voltage properties. We report accurate on-top imaging and I-V characterization of individual as-grown nanowires, using a subnanometer resolution scanning tunneling microscope with no need for additional microscopy tools, thus allowing versatile application. We form Ohmic contacts to InP and InAs nanowires without any sample processing, followed by quantitative measurements of diameter dependent I-V properties with a very small spread in measured values compared to standard techniques.

Solid-state optical microscope

DOEpatents

Young, I.T.

1981-01-07

A solid state optical microscope is described wherein wide-field and high-resolution images of an object are produced at a rapid rate by utilizing conventional optics with a charge-coupled photodiode array. Means for scanning in one of two orthogonal directions are provided, while the charge-coupled photodiode array scans in the other orthogonal direction. Illumination light from the object is incident upon the photodiodes, creating packets of electrons (signals) which are representative of the illuminated object. The signals are then processed, stored in a memory, and finally displayed as a video signal.

A scanning transmission electron microscopy approach to analyzing large volumes of tissue to detect nanoparticles.

PubMed

Kempen, Paul J; Thakor, Avnesh S; Zavaleta, Cristina; Gambhir, Sanjiv S; Sinclair, Robert

2013-10-01

The use of nanoparticles for the diagnosis and treatment of cancer requires the complete characterization of their toxicity, including accurately locating them within biological tissues. Owing to their size, traditional light microscopy techniques are unable to resolve them. Transmission electron microscopy provides the necessary spatial resolution to image individual nanoparticles in tissue, but is severely limited by the very small analysis volume, usually on the order of tens of cubic microns. In this work, we developed a scanning transmission electron microscopy (STEM) approach to analyze large volumes of tissue for the presence of polyethylene glycol-coated Raman-active-silica-gold-nanoparticles (PEG-R-Si-Au-NPs). This approach utilizes the simultaneous bright and dark field imaging capabilities of STEM along with careful control of the image contrast settings to readily identify PEG-R-Si-Au-NPs in mouse liver tissue without the need for additional time-consuming analytical characterization. We utilized this technique to analyze 243,000 mm³ of mouse liver tissue for the presence of PEG-R-Si-Au-NPs. Nanoparticles injected into the mice intravenously via the tail vein accumulated in the liver, whereas those injected intrarectally did not, indicating that they remain in the colon and do not pass through the colon wall into the systemic circulation.

A Scanning Transmission Electron Microscopy (STEM) Approach to Analyzing Large Volumes of Tissue to Detect Nanoparticles

PubMed Central

Kempen, Paul J.; Thakor, Avnesh S.; Zavaleta, Cristina; Gambhir, Sanjiv S.; Sinclair, Robert

2013-01-01

The use of nanoparticles for the diagnosis and treatment of cancer requires the complete characterization of their toxicity, including accurately locating them within biological tissues. Owing to their size, traditional light microscopy techniques are unable to resolve them. Transmission electron microscopy provides the necessary spatial resolution to image individual nanoparticles in tissue but is severely limited by the very small analysis volume, usually on the order of tens of cubic microns. In this work we developed a scanning transmission electron microscopy (STEM) approach to analyze large volumes of tissue for the presence of polyethylene glycol coated Raman-active-silica-gold-nanoparticles (PEG-R-Si-Au-NPs). This approach utilizes the simultaneous bright and dark field imaging capabilities of STEM along with careful control of the image contrast settings to readily identify PEG-R-Si-Au-NPs in mouse liver tissue without the need for additional time consuming analytical characterization. We utilized this technique to analyze 243,000 µm3 of mouse liver tissue for the presence of PEG-R-Si-Au-NPs. Nanoparticles injected into the mice intravenously via the tail-vein accumulated in the liver while those injected intrarectally did not, indicating that they remain in the colon and do not pass through the colon wall into the systemic circulation. PMID:23803218

Simulation and Characterization of a Miniaturized Scanning Electron Microscope

NASA Technical Reports Server (NTRS)

Gaskin, Jessica A.; Jerman, Gregory A.; Medley, Stephanie; Gregory, Don; Abbott, Terry O.; Sampson, Allen R.

2011-01-01

A miniaturized Scanning Electron Microscope (mSEM) for in-situ lunar investigations is being developed at NASA Marshall Space Flight Center with colleagues from the University of Alabama in Huntsville (UAH), Advanced Research Systems (ARS), the University of Tennessee in Knoxville (UTK) and Case Western Reserve University (CWRU). This effort focuses on the characterization of individual components of the mSEM and simulation of the complete system. SEMs can provide information on the size, shape, morphology and chemical composition of lunar regolith. Understanding these basic properties will allow us to better estimate the challenges associated with In-Situ Resource Utilization and to improve our basic science knowledge of the lunar surface (either precluding the need for sample return or allowing differentiation of unique samples to be returned to Earth.) The main components of the mSEM prototype includes: a cold field emission electron gun (CFEG), focusing lens, deflection/scanning system and backscatter electron detector. Of these, the electron gun development is of particular importance as it dictates much of the design of the remaining components. A CFEG was chosen for use with the lunar mSEM as its emission does not depend on heating of the tungsten emitter (lower power), it offers a long operation lifetime, is orders of magnitude brighter than tungsten hairpin guns, has a small source size and exhibits low beam energy spread.

Cyclotron autoresonant accelerator for electron beam dry scrubbing of flue gases

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaPointe, M. A.; Hirshfield, J. L.; Department of Physics, Yale University, P.O. Box 208124, New Haven, Connecticut 06520-8124

1999-06-10

Design and construction is underway for a novel rf electron accelerator for electron beam dry scrubbing (EBDS) of flue gases emanating from fossil-fuel burners. This machine, a cyclotron autoresonance accelerator (CARA), has already shown itself capable of converting rf power to electron beam power with efficiency values as high as 96%. This proof-of-principle experiment will utilize a 300 kV, 33 A Pierce type electron gun and up to 24 MW of available rf power at 2.856 GHz to produce 1.0 MeV, 33 MW electron beam pulses. The self-scanning conical beam from the high power CARA will be evaluated for EBDSmore » and other possible environmental applications.« less

Fabrication of plasmonic nanopore by using electron beam irradiation for optical bio-sensor

NASA Astrophysics Data System (ADS)

Choi, Seong Soo; Park, Myoung Jin; Han, Chul Hee; Oh, Seh Joong; Park, Nam Kyou; Park, Doo Jae; Choi, Soo Bong; Kim, Yong-Sang

2017-05-01

The Au nano-hole surrounded by the periodic nano-patterns would provide the enhanced optical intensity. Hence, the nano-hole surrounded with periodic groove patterns can be utilized as single molecule nanobio optical sensor device. In this report, the nano-hole on the electron beam induced membrane surrounded by periodic groove patterns were fabricated by focused ion beam technique (FIB), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Initially, the Au films with three different thickness of 40 nm, 60 nm, and 200 nm were deposited on the SiN film by using an electron beam sputter-deposition technique, followed by removal of the supporting SiN film. The nanopore was formed on the electron beam induced membrane under the FESEM electron beam irradiation. Nanopore formation inside the Au aperture was controlled down to a few nanometer, by electron beam irradiations. The optical intensities from the biomolecules on the surfaces including Au coated pyramid with periodic groove patterns were investigated via surface enhanced Raman spectroscopy (SERS). The fabricated nanopore surrounded by periodic patterns can be utilized as a next generation single molecule bio optical sensor.

Cyclotron autoresonant accelerator for electron beam dry scrubbing of flue gases

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaPointe, M.A.; Hirshfield, J.L.; Hirshfield, J.L.

1999-06-01

Design and construction is underway for a novel rf electron accelerator for electron beam dry scrubbing (EBDS) of flue gases emanating from fossil-fuel burners. This machine, a cyclotron autoresonance accelerator (CARA), has already shown itself capable of converting rf power to electron beam power with efficiency values as high as 96{percent}. This proof-of-principle experiment will utilize a 300 kV, 33 A Pierce type electron gun and up to 24 MW of available rf power at 2.856 GHz to produce 1.0 MeV, 33 MW electron beam pulses. The self-scanning conical beam from the high power CARA will be evaluated for EBDSmore » and other possible environmental applications. {copyright} {ital 1999 American Institute of Physics.}« less

Scanning Synchronization of Colliding Bunches for MEIC Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Derbenev, Yaroslav S.; Popov, V. P.; Chernousov, Yu D.

2015-09-01

Synchronization of colliding beams is one of the major issues of an electron-ion collider (EIC) design because of sensitivity of ion revolution frequency to beam energy. A conventional solution for this trouble is insertion of bent chicanes in the arcs space. In our report we consider a method to provide space coincidence of encountering bunches in the crab-crossing orbits Interaction Region (IR) while repetition rates of two beams do not coincide. The method utilizes pair of fast kickers realizing a bypass for the electron bunches as the way to equalize positions of the colliding bunches at the Interaction Point (IP).more » A dipole-mode warm or SRF cavities fed by the magnetron transmitters are used as fast kickers, allowing a broad-band phase and amplitude control. The proposed scanning synchronization method implies stabilization of luminosity at a maximum via a feedback loop. This synchronization method is evaluated as perspective for the Medium Energy Electron-Ion collider (MEIC) project of JLab with its very high bunch repetition rate.« less

Three-dimensional nanoscale imaging by plasmonic Brownian microscopy

NASA Astrophysics Data System (ADS)

Labno, Anna; Gladden, Christopher; Kim, Jeongmin; Lu, Dylan; Yin, Xiaobo; Wang, Yuan; Liu, Zhaowei; Zhang, Xiang

2017-12-01

Three-dimensional (3D) imaging at the nanoscale is a key to understanding of nanomaterials and complex systems. While scanning probe microscopy (SPM) has been the workhorse of nanoscale metrology, its slow scanning speed by a single probe tip can limit the application of SPM to wide-field imaging of 3D complex nanostructures. Both electron microscopy and optical tomography allow 3D imaging, but are limited to the use in vacuum environment due to electron scattering and to optical resolution in micron scales, respectively. Here we demonstrate plasmonic Brownian microscopy (PBM) as a way to improve the imaging speed of SPM. Unlike photonic force microscopy where a single trapped particle is used for a serial scanning, PBM utilizes a massive number of plasmonic nanoparticles (NPs) under Brownian diffusion in solution to scan in parallel around the unlabeled sample object. The motion of NPs under an evanescent field is three-dimensionally localized to reconstruct the super-resolution topology of 3D dielectric objects. Our method allows high throughput imaging of complex 3D structures over a large field of view, even with internal structures such as cavities that cannot be accessed by conventional mechanical tips in SPM.

Moessbauer spectroscopy and scanning electron microscopy of the Murchison meteorite

NASA Technical Reports Server (NTRS)

Brown, Christopher L.; Oliver, Frederick W.; Hammond, Ernest C., Jr.

1989-01-01

Meteorites provide a wealth of information about the solar system's formation, since they have similar building blocks as the Earth's crust but have been virtually unaltered since their formation. Some stony meteorites contain minerals and silicate inclusions, called chondrules, in the matrix. Utilizing Moessbauer spectroscopy, we identified minerals in the Murchison meteorite, a carbonaceous chondritic meteorite, by the gamma ray resonance lines observed. Absorption patterns of the spectra were found due to the minerals olivine and phyllosilicate. We used a scanning electron microscope to describe the structure of the chondrules in the Murchison meteorite. The chondrules were found to be deformed due to weathering of the meteorite. Diameters varied in size from 0.2 to 0.5 mm. Further enhancement of the microscopic imagery using a digital image processor was used to describe the physical characteristics of the inclusions.

Germination and Outgrowth of Single Spores of Saccharomyces cerevisiae Viewed by Scanning Electron and Phase-Contrast Microscopy

PubMed Central

Rousseau, Paul; Halvorson, Harlyn O.; Bulla, Lee A.; Julian, Grant St.

1972-01-01

Single spores of Saccharomyces cerevisiae were examined during germination and outgrowth by scanning electron and phase-contrast microscopy. Also determined were changes in cell weight and light absorbance, trehalose utilization, and synthesis of protein and KOH-soluble carbohydrates. These studies reveal that development of the vegetative cell from a spore follows a definite sequence of events involving dramatic physical and chemical modifications. These changes are: initial rapid loss in cellular absorbance followed later by an abrupt gain in absorbance; reduction in cell weight and a subsequent progressive increase; modification of the spore surface with concomitant diminution in refractility; elongation of the cell and augmentation of surface irregularities; rapid decline in trehalose content of the cell accompanied by extensive formation of KOH-soluble carbohydrates; and bud formation. Images PMID:4551750

Spectroscopic study of Pbs nano-structured layer prepared by Pld utilized as a Hall-effect magnetic sensor

NASA Astrophysics Data System (ADS)

Atwa, D. M.; Aboulfotoh, N.; El-magd, A. Abo; Badr, Y.

2013-10-01

Lead sulfide (PbS) nano-structured films have been grown on quartz substrates using PLD technique. The deposited films were characterized by several structural techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Selected-area electron diffraction patterns (SAED). The results prove the formation of cubic phase of PbS nanocrystals. Elemental analysis of the deposited films compared to the bulk target was obtained via laser induced fluorescence of the produced plasma particles and the energy dispersive X-ray "EDX" technique. The Hall coefficient measurements indicate an efficient performance of the deposited films as a magnetic sensor.

Procedures for analysis of debris relative to Space Shuttle systems

NASA Technical Reports Server (NTRS)

Kim, Hae Soo; Cummings, Virginia J.

1993-01-01

Debris samples collected from various Space Shuttle systems have been submitted to the Microchemical Analysis Branch. This investigation was initiated to develop optimal techniques for the analysis of debris. Optical microscopy provides information about the morphology and size of crystallites, particle sizes, amorphous phases, glass phases, and poorly crystallized materials. Scanning electron microscopy with energy dispersive spectrometry is utilized for information on surface morphology and qualitative elemental content of debris. Analytical electron microscopy with wavelength dispersive spectrometry provides information on the quantitative elemental content of debris.

3D-measurement using a scanning electron microscope with four Everhart-Thornley detectors

NASA Astrophysics Data System (ADS)

Vynnyk, Taras; Scheuer, Renke; Reithmeier, Eduard

2011-06-01

Due to the emerging degree of miniaturization in microstructures, Scanning-Electron-Microscopes (SEM) have become important instruments in the quality assurance of chip manufacturing. With a two- or multiple detector system for secondary electrons, a SEM can be used for the reconstruction of three dimensional surface profiles. Although there are several projects dealing with the reconstruction of three dimensional surfaces using electron microscopes with multiple Everhart-Thornley detectors (ETD), there is no profound knowledge of the behaviour of emitted electrons. Hence, several values, which are used for reconstruction algorithms, such as the photometric method, are only estimates; for instance, the exact collection efficiency of the ETD, which is still unknown. This paper deals with the simulation of electron trajectories in a one-, two- and four-detector system with varying working distances and varying grid currents. For each detector, the collection efficiency is determined by taking the working distance and grid current into account. Based on the gathered information, a new collection grid, which provides a homogenous emission signal for each detector of a multiple detector system, is developed. Finally, the results of the preceding tests are utilized for a reconstruction of a three dimensional surface using the photometric method with a non-lambert intensity distribution.

Two-stages of chiral selectivity in the molecular self-assembly of tryptophan

NASA Astrophysics Data System (ADS)

Guisinger, Nathan

Both chirality and molecular assembly are essential and key components to life. In this study we explore the molecular assembly of the amino acid tryptophan (both L- and D- chiralities) on Cu(111). Our investigation utilizes low temperature scanning tunneling microscopy to observe resulting assemblies at the molecular scale. We find that depositing a racemic mixture of both L- and D- tryptophan results in the assembly of basic 6 molecule ``Lego'' structures that are enantiopure. These enantiopure ``Legos'' further assemble into 1-dimensional chains one block at a time. These resulting chains are also enantiopure with chiral selectivity occurring at two stages of assembly. Utilizing scanning tunneling spectroscopy we are able to probe the electronic structure of the chiral Legos that give insight into the root of the observed selectivity. Two-stages of chiral selectivity in the molecular self-assembly of tryptophan.

Evaluation of environmental scanning electron microscopy for analysis of Proteus mirabilis crystalline biofilms in situ on urinary catheters

PubMed Central

Holling, Nina; Dedi, Cinzia; Jones, Caroline E; Hawthorne, Joseph A; Hanlon, Geoffrey W; Salvage, Jonathan P; Patel, Bhavik A; Barnes, Lara M; Jones, Brian V

2014-01-01

Proteus mirabilis is a common cause of catheter-associated urinary tract infections and frequently leads to blockage of catheters due to crystalline biofilm formation. Scanning electron microscopy (SEM) has proven to be a valuable tool in the study of these unusual biofilms, but entails laborious sample preparation that can introduce artefacts, undermining the investigation of biofilm development. In contrast, environmental scanning electron microscopy (ESEM) permits imaging of unprocessed, fully hydrated samples, which may provide much insight into the development of P. mirabilis biofilms. Here, we evaluate the utility of ESEM for the study of P. mirabilis crystalline biofilms in situ, on urinary catheters. In doing so, we compare this to commonly used conventional SEM approaches for sample preparation and imaging. Overall, ESEM provided excellent resolution of biofilms formed on urinary catheters and revealed structures not observed in standard SEM imaging or previously described in other studies of these biofilms. In addition, we show that energy-dispersive X-ray spectroscopy (EDS) may be employed in conjunction with ESEM to provide information regarding the elemental composition of crystalline structures and demonstrate the potential for ESEM in combination with EDS to constitute a useful tool in exploring the mechanisms underpinning crystalline biofilm formation. PMID:24786314

A versatile atomic force microscope integrated with a scanning electron microscope.

PubMed

Kreith, J; Strunz, T; Fantner, E J; Fantner, G E; Cordill, M J

2017-05-01

A versatile atomic force microscope (AFM), which can be installed in a scanning electron microscope (SEM), is introduced. The flexible design of the instrument enables correlated analysis for different experimental configurations, such as AFM imaging directly after nanoindentation in vacuum. In order to demonstrate the capabilities of the specially designed AFM installed inside a SEM, slip steps emanating around nanoindents in single crystalline brass were examined. This example showcases how the combination of AFM and SEM imaging can be utilized for quantitative dislocation analysis through the measurement of the slip step heights without the hindrance of oxide formation. Finally, an in situ nanoindentation technique is introduced, illustrating the use of AFM imaging during indentation experiments to examine plastic deformation occurring under the indenter tip. The mechanical indentation data are correlated to the SEM and AFM images to estimate the number of dislocations emitted to the surface.

Contextualizing Technology in the Classroom via Remote Access: Using Space Exploration Themes and Scanning Electron Microscopy as Tools to Promote Engagement in Geology/Chemistry Experiments

ERIC Educational Resources Information Center

Rodriguez, Brandon; Jaramillo, Veronica; Wolf, Vanessa; Bautista, Esteban; Portillo, Jennifer; Brouke, Alexandra; Min, Ashley; Melendez, Andrea; Amann, Joseph; Pena-Francesch, Abdon; Ashcroft, Jared

2018-01-01

A multidisciplinary science experiment was performed in K-12 classrooms focusing on the interconnection between technology with geology and chemistry. The engagement and passion for science of over eight hundred students across twenty-one classrooms, utilizing a combination of hands-on activities using relationships between Earth and space rock…

Field emission scanning electron microscopy (FE-SEM) as an approach for nanoparticle detection inside cells.

PubMed

Havrdova, M; Polakova, K; Skopalik, J; Vujtek, M; Mokdad, A; Homolkova, M; Tucek, J; Nebesarova, J; Zboril, R

2014-12-01

When developing new nanoparticles for bio-applications, it is important to fully characterize the nanoparticle's behavior in biological systems. The most common techniques employed for mapping nanoparticles inside cells include transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). These techniques entail passing an electron beam through a thin specimen. STEM or TEM imaging is often used for the detection of nanoparticles inside cellular organelles. However, lengthy sample preparation is required (i.e., fixation, dehydration, drying, resin embedding, and cutting). In the present work, a new matrix (FTO glass) for biological samples was used and characterized by field emission scanning electron microscopy (FE-SEM) to generate images comparable to those obtained by TEM. Using FE-SEM, nanoparticle images were acquired inside endo/lysosomes without disruption of the cellular shape. Furthermore, the initial steps of nanoparticle incorporation into the cells were captured. In addition, the conductive FTO glass endowed the sample with high stability under the required accelerating voltage. Owing to these features of the sample, further analyses could be performed (material contrast and energy-dispersive X-ray spectroscopy (EDS)), which confirmed the presence of nanoparticles inside the cells. The results showed that FE-SEM can enable detailed characterization of nanoparticles in endosomes without the need for contrast staining or metal coating of the sample. Images showing the intracellular distribution of nanoparticles together with cellular morphology can give important information on the biocompatibility and demonstrate the potential of nanoparticle utilization in medicine. Copyright © 2014 Elsevier Ltd. All rights reserved.

Simultaneous Scanning Electron Microscope Imaging of Topographical and Chemical Contrast Using In-Lens, In-Column, and Everhart-Thornley Detector Systems.

PubMed

Zhang, Xinming; Cen, Xi; Ravichandran, Rijuta; Hughes, Lauren A; van Benthem, Klaus

2016-06-01

The scanning electron microscope provides a platform for subnanometer resolution characterization of material morphology with excellent topographic and chemical contrast dependent on the used detectors. For imaging applications, the predominantly utilized signals are secondary electrons (SEs) and backscattered electrons (BSEs) that are emitted from the sample surface. Recent advances in detector technology beyond the traditional Everhart-Thornley geometry have enabled the simultaneous acquisition and discrimination of SE and BSE signals. This study demonstrates the imaging capabilities of a recently introduced new detector system that consists of the combination of two in-lens (I-L) detectors and one in-column (I-C) detector. Coupled with biasing the sample stage to reduce electron-specimen interaction volumes, this trinity of detector geometry allows simultaneous acquisition of signals to distinguish chemical contrast from topographical changes of the sample, including the identification of surface contamination. The I-C detector provides 4× improved topography, whereas the I-L detector closest to the sample offers excellent simultaneous chemical contrast imaging while not limiting the minimization of working distance to obtain optimal lateral resolution. Imaging capabilities and contrast mechanisms for all three detectors are discussed quantitatively in direct comparison to each other and the conventional Everhart-Thornley detector.

Au particle formation on the electron beam induced membrane

NASA Astrophysics Data System (ADS)

Choi, Seong Soo; Park, Myoung Jin; Han, Chul Hee; Oh, Sae-Joong; Kim, Sung-In; Park, Nam Kyou; Park, Doo-Jae; Choi, Soo Bong; Kim, Yong-Sang

2017-02-01

Recently the single molecules such as protein and deoxyribonucleic acid (DNA) have been successfully characterized by using a portable solidstate nanopore (MinION) with an electrical detection technique. However, there have been several reports about the high error rates of the fabricated nanopore device, possibly due to an electrical double layer formed inside the pore channel. The current DNA sequencing technology utilized is based on the optical detection method. In order to utilize the current optical detection technique, we will present the formation of the Au nano-pore with Au particle under the various electron beam irradiations. In order to provide the diffusion of Au atoms, a 2 keV electron beam irradiation has been performed During electron beam irradiations by using field emission scanning electron microscopy (FESEM), Au and C atoms would diffuse together and form the binary mixture membrane. Initially, the Au atoms diffused in the membrane are smaller than 1 nm, below the detection limit of the transmission electron microscopy (TEM), so that we are unable to observe the Au atoms in the formed membrane. However, after several months later, the Au atoms became larger and larger with expense of the smaller particles: Ostwald ripening. Furthermore, we also observe the Au crystalline lattice structure on the binary Au-C membrane. The formed Au crystalline lattice structures were constantly changing during electron beam imaging process due to Spinodal decomposition; the unstable thermodynamic system of Au-C binary membrane. The fabricated Au nanopore with an Au nanoparticle can be utilized as a single molecule nanobio sensor.

Software electron counting for low-dose scanning transmission electron microscopy.

PubMed

Mittelberger, Andreas; Kramberger, Christian; Meyer, Jannik C

2018-05-01

The performance of the detector is of key importance for low-dose imaging in transmission electron microscopy, and counting every single electron can be considered as the ultimate goal. In scanning transmission electron microscopy, low-dose imaging can be realized by very fast scanning, however, this also introduces artifacts and a loss of resolution in the scan direction. We have developed a software approach to correct for artifacts introduced by fast scans, making use of a scintillator and photomultiplier response that extends over several pixels. The parameters for this correction can be directly extracted from the raw image. Finally, the images can be converted into electron counts. This approach enables low-dose imaging in the scanning transmission electron microscope via high scan speeds while retaining the image quality of artifact-free slower scans. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Nanostitched Composites with Improved Interlaminar and Intralaminar Strengths for Advanced Airframes in Sea-based Aviation

DTIC Science & Technology

2017-04-13

experimental  and  engineering  expertise...ex   situ,  and   preliminary  in   situ,   experimental   program   utilizing  optical  microscopy,   scanning  electron...modeling,  as  well  as   through  working  with  NAVAIR   for  guidance  on  several   topics  including   experimental

Space Technology for Palate Surgery

NASA Technical Reports Server (NTRS)

1980-01-01

University of Miami utilized NASA's spacecraft viewing technology to develop the optical profilometer provides more accurate measurements of cleft palate casts than has heretofore been possible, enabling better planning of corrective surgery. Lens like instrument electronically scans a palate cast precisely measuring its irregular contours by detecting minute differences in the intensity of a light beam reflected off the cast. Readings are computer processed and delivered to the surgeon by a teleprinter.

Advanced Electron Holography Applied to Electromagnetic Field Study in Materials Science.

PubMed

Shindo, Daisuke; Tanigaki, Toshiaki; Park, Hyun Soon

2017-07-01

Advances and applications of electron holography to the study of electromagnetic fields in various functional materials are presented. In particular, the development of split-illumination electron holography, which introduces a biprism in the illumination system of a holography electron microscope, enables highly accurate observations of electromagnetic fields and the expansion of the observable area. First, the charge distributions on insulating materials were studied by using split-illumination electron holography and including a mask in the illumination system. Second, the three-dimensional spin configurations of skyrmion lattices in a helimagnet were visualized by using a high-voltage holography electron microscope. Third, the pinning of the magnetic flux lines in a high-temperature superconductor YBa 2 Cu 3 O 7-y was analyzed by combining electron holography and scanning ion microscopy. Finally, the dynamic accumulation and collective motions of electrons around insulating biomaterial surfaces were observed by utilizing the amplitude reconstruction processes of electron holography. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modeling of profilometry with laser focus sensors

NASA Astrophysics Data System (ADS)

Bischoff, Jörg; Manske, Eberhard; Baitinger, Henner

2011-05-01

Metrology is of paramount importance in submicron patterning. Particularly, line width and overlay have to be measured very accurately. Appropriated metrology techniques are scanning electron microscopy and optical scatterometry. The latter is non-invasive, highly accurate and enables optical cross sections of layer stacks but it requires periodic patterns. Scanning laser focus sensors are a viable alternative enabling the measurement of non-periodic features. Severe limitations are imposed by the diffraction limit determining the edge location accuracy. It will be shown that the accuracy can be greatly improved by means of rigorous modeling. To this end, a fully vectorial 2.5-dimensional model has been developed based on rigorous Maxwell solvers and combined with models for the scanning and various autofocus principles. The simulations are compared with experimental results. Moreover, the simulations are directly utilized to improve the edge location accuracy.

Phased Array-Fed Reflector (PAFR) Antenna Architectures for Space-Based Sensors

NASA Technical Reports Server (NTRS)

Cooley, Michael E.

2014-01-01

Communication link and target ranges for satellite communications (SATCOM) and space-based sensors (e.g. radars) vary from approximately 1000 km (for LEO satellites) to 35,800 km (for GEO satellites). At these long ranges, large antenna gains are required and legacy payloads have usually employed large reflectors with single beams that are either fixed or mechanically steered. For many applications, there are inherent limitations that are associated with the use of these legacy antennas/payloads. Hybrid antenna designs using Phased Array Fed Reflectors (PAFRs) provide a compromise between reflectors and Direct Radiating phased Arrays (DRAs). PAFRs provide many of the performance benefits of DRAs while utilizing much smaller, lower cost (feed) arrays. The primary limitation associated with hybrid PAFR architectures is electronic scan range; approximately +/-5 to +/- 10 degrees is typical, but this range depends on many factors. For LEO applications, the earth FOV is approximately +/-55 degrees which is well beyond the range of electronic scanning for PAFRs. However, for some LEO missions, limited scanning is sufficient or the CONOPS and space vehicle designs can be developed to incorporate a combination mechanical slewing and electronic scanning. In this paper, we review, compare and contrast various PAFR architectures with a focus on their general applicability to space missions. We compare the RF performance of various PAFR architectures and describe key hardware design and implementation trades. Space-based PAFR designs are highly multi-disciplinary and we briefly address key hardware engineering design areas. Finally, we briefly describe two PAFR antenna architectures that have been developed at Northrop Grumman.

Evaluation of environmental scanning electron microscopy for analysis of Proteus mirabilis crystalline biofilms in situ on urinary catheters.

PubMed

Holling, Nina; Dedi, Cinzia; Jones, Caroline E; Hawthorne, Joseph A; Hanlon, Geoffrey W; Salvage, Jonathan P; Patel, Bhavik A; Barnes, Lara M; Jones, Brian V

2014-06-01

Proteus mirabilis is a common cause of catheter-associated urinary tract infections and frequently leads to blockage of catheters due to crystalline biofilm formation. Scanning electron microscopy (SEM) has proven to be a valuable tool in the study of these unusual biofilms, but entails laborious sample preparation that can introduce artefacts, undermining the investigation of biofilm development. In contrast, environmental scanning electron microscopy (ESEM) permits imaging of unprocessed, fully hydrated samples, which may provide much insight into the development of P. mirabilis biofilms. Here, we evaluate the utility of ESEM for the study of P. mirabilis crystalline biofilms in situ, on urinary catheters. In doing so, we compare this to commonly used conventional SEM approaches for sample preparation and imaging. Overall, ESEM provided excellent resolution of biofilms formed on urinary catheters and revealed structures not observed in standard SEM imaging or previously described in other studies of these biofilms. In addition, we show that energy-dispersive X-ray spectroscopy (EDS) may be employed in conjunction with ESEM to provide information regarding the elemental composition of crystalline structures and demonstrate the potential for ESEM in combination with EDS to constitute a useful tool in exploring the mechanisms underpinning crystalline biofilm formation. © 2014 The Authors. FEMS Microbiology Letters published by John Wiley & Sons Ltd on behalf of Federation of European Microbiological Societies.

A versatile LabVIEW and field-programmable gate array-based scanning probe microscope for in operando electronic device characterization.

PubMed

Berger, Andrew J; Page, Michael R; Jacob, Jan; Young, Justin R; Lewis, Jim; Wenzel, Lothar; Bhallamudi, Vidya P; Johnston-Halperin, Ezekiel; Pelekhov, Denis V; Hammel, P Chris

2014-12-01

Understanding the complex properties of electronic and spintronic devices at the micro- and nano-scale is a topic of intense current interest as it becomes increasingly important for scientific progress and technological applications. In operando characterization of such devices by scanning probe techniques is particularly well-suited for the microscopic study of these properties. We have developed a scanning probe microscope (SPM) which is capable of both standard force imaging (atomic, magnetic, electrostatic) and simultaneous electrical transport measurements. We utilize flexible and inexpensive FPGA (field-programmable gate array) hardware and a custom software framework developed in National Instrument's LabVIEW environment to perform the various aspects of microscope operation and device measurement. The FPGA-based approach enables sensitive, real-time cantilever frequency-shift detection. Using this system, we demonstrate electrostatic force microscopy of an electrically biased graphene field-effect transistor device. The combination of SPM and electrical transport also enables imaging of the transport response to a localized perturbation provided by the scanned cantilever tip. Facilitated by the broad presence of LabVIEW in the experimental sciences and the openness of our software solution, our system permits a wide variety of combined scanning and transport measurements by providing standardized interfaces and flexible access to all aspects of a measurement (input and output signals, and processed data). Our system also enables precise control of timing (synchronization of scanning and transport operations) and implementation of sophisticated feedback protocols, and thus should be broadly interesting and useful to practitioners in the field.

A versatile LabVIEW and field-programmable gate array-based scanning probe microscope for in operando electronic device characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berger, Andrew J., E-mail: berger.156@osu.edu; Page, Michael R.; Young, Justin R.

Understanding the complex properties of electronic and spintronic devices at the micro- and nano-scale is a topic of intense current interest as it becomes increasingly important for scientific progress and technological applications. In operando characterization of such devices by scanning probe techniques is particularly well-suited for the microscopic study of these properties. We have developed a scanning probe microscope (SPM) which is capable of both standard force imaging (atomic, magnetic, electrostatic) and simultaneous electrical transport measurements. We utilize flexible and inexpensive FPGA (field-programmable gate array) hardware and a custom software framework developed in National Instrument's LabVIEW environment to perform themore » various aspects of microscope operation and device measurement. The FPGA-based approach enables sensitive, real-time cantilever frequency-shift detection. Using this system, we demonstrate electrostatic force microscopy of an electrically biased graphene field-effect transistor device. The combination of SPM and electrical transport also enables imaging of the transport response to a localized perturbation provided by the scanned cantilever tip. Facilitated by the broad presence of LabVIEW in the experimental sciences and the openness of our software solution, our system permits a wide variety of combined scanning and transport measurements by providing standardized interfaces and flexible access to all aspects of a measurement (input and output signals, and processed data). Our system also enables precise control of timing (synchronization of scanning and transport operations) and implementation of sophisticated feedback protocols, and thus should be broadly interesting and useful to practitioners in the field.« less

Investigating the performance of nitrogen-doped graphene photoanode in dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Joseph, Easter; Singh, Balbir Singh Mahinder; Mohamed, Norani Muti; Kait, Chong Fai; Saheed, Mohamed Shuaib Mohamed; Khatani, Mehboob

2016-11-01

In this paper, the atmospheric pressure chemical vapor deposition (AP-CVD) is used to synthesize graphene on a copper substrate by utilizing methane as a precursor and N-doped graphene (NDG) in the presence of ammonia. The performance of pure titanium dioxide (TiO2), TiO2/graphene, and TiO2/NDG as photoanodes in dye-sensitized solar cell (DSSC) were compared. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) showed flakes of few layers with an interrupted layer in both graphene and NDG. DSSC consist of TiO2/NDG photoanode exhibits a better enhancement due to the high conductivity of donor N in graphene which enhances the electron transportation across nanoporous TiO2.

Technology Assessment: 1983 Forecast of Future Test Technology Requirements.

DTIC Science & Technology

1983-06-01

effectively utilizes existing vehicle space , power and support equipment while maintaining critical interfaces with on-board computers and fire control...Scan Converter EAR Electronically Agile Radar E-O Electro-Optics FET Field Effect Transistor FLIR Forward Looking Infrared GaAs Gallium Arsenide HEL...They might be a part of a large ATE system due to such things as the environmental effects on noise and signal/power loss. A summary of meaningful

Line-edge quality optimization of electron beam resist for high-throughput character projection exposure utilizing atomic force microscope analysis

NASA Astrophysics Data System (ADS)

Ikeno, Rimon; Mita, Yoshio; Asada, Kunihiro

2017-04-01

High-throughput electron-beam lithography (EBL) by character projection (CP) and variable-shaped beam (VSB) methods is a promising technique for low-to-medium volume device fabrication with regularly arranged layouts, such as standard-cell logics and memory arrays. However, non-VLSI applications like MEMS and MOEMS may not fully utilize the benefits of CP method due to their wide variety of layout figures including curved and oblique edges. In addition, the stepwise shapes that appear on such irregular edges by VSB exposure often result in intolerable edge roughness, which may degrade performances of the fabricated devices. In our former study, we proposed a general EBL methodology for such applications utilizing a combination of CP and VSB methods, and demonstrated its capabilities in electron beam (EB) shot reduction and edge-quality improvement by using a leading-edge EB exposure tool, ADVANTEST F7000S-VD02, and high-resolution Hydrogen Silsesquioxane resist. Both scanning electron microscope and atomic force microscope observations were used to analyze quality of the resist edge profiles to determine the influence of the control parameters used in the exposure-data preparation process. In this study, we carried out detailed analysis of the captured edge profiles utilizing Fourier analysis, and successfully distinguish the systematic undulation by the exposed CP character profiles from random roughness components. Such capability of precise edge-roughness analysis is useful to our EBL methodology to maintain both the line-edge quality and the exposure throughput by optimizing the control parameters in the layout data conversion.

Corrosion behavior of surface films on boron-implanted high purity iron and stainless steels

NASA Technical Reports Server (NTRS)

Kim, H. J.; Carter, W. B.; Hochman, R. F.; Meletis, E. I.

1985-01-01

Boron (dose, 2 x 10 to the 17th ions/sq cm) was implanted into high purity iron, AISI 316 austenitic stainless steel, and AISI 440C martensitic stainless steel, at 40 keV. The film structure of implanted samples was examined and characterized by contrast and diffraction analyses utilizing transmission electron microscopy. The effect of B(+) ion implantation on the corrosion behavior was studied using the potentiodynamic polarization technique. Tests were performed in deaerated 1 N H2SO4 and 0.1 M NaCl solutions. Scanning electron microscopy was used to examine the morphology of the corroded surfaces after testing.

The effects of acid erosion and remineralization on enamel and three different dental materials: FT-Raman spectroscopy and scanning electron microscopy analysis.

PubMed

Soares, Luís Eduardo Silva; Soares, Ana Lúcia Silva; De Oliveira, Rodrigo; Nahórny, Sidnei

2016-07-01

FT-Raman spectroscopy and scanning electron microscopy (SEM) were employed to test the hypothesis that the beverage consumption or mouthwash utilization would change the chemistry of dental materials and enamel inorganic content. Bovine enamel samples (n = 36) each received two cavity preparations (n = 72), each pair filled with one of three dental materials (R: nanofilled composite resin, GIC: glass-ionomer cement, RMGIC: resin-modified GIC). Furthermore, they were treated with three different solutions (S: artificial saliva, E: erosion/Pepsi Twist or EM: erosion + mouthwash/Colgate Plax). Reduction of carbonate content of enamel was greater in RE than RS (P < 0.01). Increment of carbonate was greater in GICEM than in GICE and GICS (P < 0.01; P < 0.001). Significant material degradation was found in RE, REM, GICE, and GICEM than in RS and GICS (P < 0.01; P < 0.001). SEM showed clear enamel demineralization after erosion. Material degradation was greater after E and EM than S. GIC and RMGIC materials had a positive effect against acid erosion in the adjacent enamel after remineralization with mouthwash. The beverage and mouthwash utilization would change R and GIC chemical properties. A professional should periodically monitor the glass-ionomer and resin restorations, as they degrade over time under erosive challenges and mouthwash utilization. Microsc. Res. Tech., 2016. © 2016 Wiley Periodicals, Inc. Microsc. Res. Tech. 79:646-656, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Characterization of conductive nanobiomaterials derived from viral assemblies by low-voltage STEM imaging and Raman scattering

NASA Astrophysics Data System (ADS)

Plascencia-Villa, Germán; Carreño-Fuentes, Liliana; Bahena, Daniel; José-Yacamán, Miguel; Palomares, Laura A.; Ramírez, Octavio T.

2014-09-01

New technologies require the development of novel nanomaterials that need to be fully characterized to achieve their potential. High-resolution low-voltage scanning transmission electron microscopy (STEM) has proven to be a very powerful technique in nanotechnology, but its use for the characterization of nanobiomaterials has been limited. Rotavirus VP6 self-assembles into nanotubular assemblies that possess an intrinsic affinity for Au ions. This property was exploited to produce hybrid nanobiomaterials by the in situ functionalization of recombinant VP6 nanotubes with gold nanoparticles. In this work, Raman spectroscopy and advanced analytical electron microscopy imaging with spherical aberration-corrected (Cs) STEM and nanodiffraction at low-voltage doses were employed to characterize nanobiomaterials. STEM imaging revealed the precise structure and arrangement of the protein templates, as well as the nanostructure and atomic arrangement of gold nanoparticles with high spatial sub-Angstrom resolution and avoided radiation damage. The imaging was coupled with backscattered electron imaging, ultra-high resolution scanning electron microscopy and x-ray spectroscopy. The hybrid nanobiomaterials that were obtained showed unique properties as bioelectronic conductive devices and showed enhanced Raman scattering by their precise arrangement into superlattices, displaying the utility of viral assemblies as functional integrative self-assembled nanomaterials for novel applications.

Investigation of nanoparticulate silicon as printed layers using scanning electron microscopy, transmission electron microscopy, X-ray absorption spectroscopy and X-ray photoelectron spectroscopy

DOE PAGES

Unuigbe, David M.; Harting, Margit; Jonah, Emmanuel O.; ...

2017-08-21

The presence of native oxide on the surface of silicon nanoparticles is known to inhibit charge transport on the surfaces. Scanning electron microscopy (SEM) studies reveal that the particles in the printed silicon network have a wide range of sizes and shapes. High-resolution transmission electron microscopy reveals that the particle surfaces have mainly the (111)- and (100)-oriented planes which stabilizes against further oxidation of the particles. X-ray absorption spectroscopy (XANES) and X-ray photoelectron spectroscopy (XPS) measurements at the O 1s-edge have been utilized to study the oxidation and local atomic structure of printed layers of silicon nanoparticles which were milledmore » for different times. XANES results reveal the presence of the +4 (SiO 2) oxidation state which tends towards the +2 (SiO) state for higher milling times. Si 2pXPS results indicate that the surfaces of the silicon nanoparticles in the printed layers are only partially oxidized and that all three sub-oxide, +1 (Si 2O), +2 (SiO) and +3 (Si 2O 3), states are present. The analysis of the change in the sub-oxide peaks of the silicon nanoparticles shows the dominance of the +4 state only for lower milling times.« less

Contact detection for nanomanipulation in a scanning electron microscope.

PubMed

Ru, Changhai; To, Steve

2012-07-01

Nanomanipulation systems require accurate knowledge of the end-effector position in all three spatial coordinates, XYZ, for reliable manipulation of nanostructures. Although the images acquired by a scanning electron microscope (SEM) provide high resolution XY information, the lack of depth information in the Z-direction makes 3D nanomanipulation time-consuming. Existing approaches for contact detection of end-effectors inside SEM typically utilize fragile touch sensors that are difficult to integrate into a nanomanipulation system. This paper presents a method for determining the contact between an end-effector and a target surface during nanomanipulation inside SEM, purely based on the processing of SEM images. A depth-from-focus method is used in the fast approach of the end-effector to the substrate, followed by fine contact detection. Experimental results demonstrate that the contact detection approach is capable of achieving an accuracy of 21.5 nm at 50,000× magnification while inducing little end-effector damage. Copyright © 2012 Elsevier B.V. All rights reserved.

WE-EF-207-07: Dual Energy CT with One Full Scan and a Second Sparse-View Scan Using Structure Preserving Iterative Reconstruction (SPIR)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, T; Zhu, L

Purpose: Conventional dual energy CT (DECT) reconstructs CT and basis material images from two full-size projection datasets with different energy spectra. To relax the data requirement, we propose an iterative DECT reconstruction algorithm using one full scan and a second sparse-view scan by utilizing redundant structural information of the same object acquired at two different energies. Methods: We first reconstruct a full-scan CT image using filtered-backprojection (FBP) algorithm. The material similarities of each pixel with other pixels are calculated by an exponential function about pixel value differences. We assume that the material similarities of pixels remains in the second CTmore » scan, although pixel values may vary. An iterative method is designed to reconstruct the second CT image from reduced projections. Under the data fidelity constraint, the algorithm minimizes the L2 norm of the difference between pixel value and its estimation, which is the average of other pixel values weighted by their similarities. The proposed algorithm, referred to as structure preserving iterative reconstruction (SPIR), is evaluated on physical phantoms. Results: On the Catphan600 phantom, SPIR-based DECT method with a second 10-view scan reduces the noise standard deviation of a full-scan FBP CT reconstruction by a factor of 4 with well-maintained spatial resolution, while iterative reconstruction using total-variation regularization (TVR) degrades the spatial resolution at the same noise level. The proposed method achieves less than 1% measurement difference on electron density map compared with the conventional two-full-scan DECT. On an anthropomorphic pediatric phantom, our method successfully reconstructs the complicated vertebra structures and decomposes bone and soft tissue. Conclusion: We develop an effective method to reduce the number of views and therefore data acquisition in DECT. We show that SPIR-based DECT using one full scan and a second 10-view scan can provide high-quality DECT images and accurate electron density maps as conventional two-full-scan DECT.« less

System and method for compressive scanning electron microscopy

DOEpatents

Reed, Bryan W

2015-01-13

A scanning transmission electron microscopy (STEM) system is disclosed. The system may make use of an electron beam scanning system configured to generate a plurality of electron beam scans over substantially an entire sample, with each scan varying in electron-illumination intensity over a course of the scan. A signal acquisition system may be used for obtaining at least one of an image, a diffraction pattern, or a spectrum from the scans, the image, diffraction pattern, or spectrum representing only information from at least one of a select subplurality or linear combination of all pixel locations comprising the image. A dataset may be produced from the information. A subsystem may be used for mathematically analyzing the dataset to predict actual information that would have been produced by each pixel location of the image.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Basavatia, A; Kalnicki, S; Garg, M

Purpose: To implement a clinically useful palm vein pattern recognition biometric system to treat the correct treatment plan to the correct patient each and every time and to check-in the patient into the department to access the correct medical record. Methods: A commercially available hand vein scanning system was paired to Aria and utilized an ADT interface from the hospital electronic health system. Integration at two points in Aria, version 11 MR2, first at the appointment tracker screen for the front desk medical record access and second at the queue screen on the 4D treatment console took place for patientmore » daily time-out. A test patient was utilized to check accuracy of identification as well as to check that no unintended interactions take place between the 4D treatment console and the hand vein scanning system. This system has been in clinical use since December 2013. Results: Since implementation, 445 patients have been enrolled into our biometric system. 95% of patients learn the correct methodology of hand placement on the scanner in the first try. We have had two instances of patient not found because of a bad initial scan. We simply erased the scanned metric and the patient enrolled again in those cases. The accuracy of the match is 100% for each patient, we have not had one patient misidentified. We can state this because we still use patient photo and date of birth as identifiers. A QA test patient is run monthly to check the integrity of the system. Conclusion: By utilizing palm vein scans along with the date of birth and patient photo, another means of patient identification now exits. This work indicates the successful implementation of technology in the area of patient safety by closing the gap of treating the wrong plan to a patient in radiation oncology. FOJP Service Corporation covered some of the costs of the hardware and software of the palm vein pattern recognition biometric system.« less

Compact antenna for two-dimensional beam scan in the JT-60U electron cyclotron heating/current drive system

NASA Astrophysics Data System (ADS)

Moriyama, S.; Kajiwara, K.; Takahashi, K.; Kasugai, A.; Seki, M.; Ikeda, Y.; Fujii, T.

2005-11-01

A compact antenna system was designed and fabricated to enable millimeter-wave beam scanning in the toroidal and poloidal directions of the JT-60U tokamak for electron cyclotron heating (ECH) and electron cyclotron current drive (ECCD) experiments. The antenna consists of a fast movable flat mirror mounted on the tokamak vacuum vessel and a rotary focusing mirror attached at the end of the waveguide that is supported from outside the vacuum vessel. This separate support concept enables a compact structure inside a shallow port (0.68×0.54×0.2m) that is shared with a subport for an independent diagnostic system. During a plasma shot, the flat mirror is driven by a servomotor with a 3-m-long drive shaft to reduce the influence of the high magnetic field on the motor. The focusing mirror is rotated by a simple mechanism utilizing a push rod and an air cylinder. The antenna has been operated reliably for 3 years after a small improvement to the rotary drive mechanism. It has made significant contributions to ECH and ECCD experiments, especially the current profile control in JT-60U.

Nitrogen implantation with a scanning electron microscope.

PubMed

Becker, S; Raatz, N; Jankuhn, St; John, R; Meijer, J

2018-01-08

Established techniques for ion implantation rely on technically advanced and costly machines like particle accelerators that only few research groups possess. We report here about a new and surprisingly simple ion implantation method that is based upon a widespread laboratory instrument: The scanning electron microscope. We show that it can be utilized to ionize atoms and molecules from the restgas by collisions with electrons of the beam and subsequently accelerate and implant them into an insulating sample by the effect of a potential building up at the sample surface. Our method is demonstrated by the implantation of nitrogen ions into diamond and their subsequent conversion to nitrogen vacancy centres which can be easily measured by fluorescence confocal microscopy. To provide evidence that the observed centres are truly generated in the way we describe, we supplied a 98% isotopically enriched 15 N gas to the chamber, whose natural abundance is very low. By employing the method of optically detected magnetic resonance, we were thus able to verify that the investigated centres are actually created from the 15 N isotopes. We also show that this method is compatible with lithography techniques using e-beam resist, as demonstrated by the implantation of lines using PMMA.

Determination of aberration center of Ronchigram for automated aberration correctors in scanning transmission electron microscopy.

PubMed

Sannomiya, Takumi; Sawada, Hidetaka; Nakamichi, Tomohiro; Hosokawa, Fumio; Nakamura, Yoshio; Tanishiro, Yasumasa; Takayanagi, Kunio

2013-12-01

A generic method to determine the aberration center is established, which can be utilized for aberration calculation and axis alignment for aberration corrected electron microscopes. In this method, decentering induced secondary aberrations from inherent primary aberrations are minimized to find the appropriate axis center. The fitness function to find the optimal decentering vector for the axis was defined as a sum of decentering induced secondary aberrations with properly distributed weight values according to the aberration order. Since the appropriate decentering vector is determined from the aberration values calculated at an arbitrary center axis, only one aberration measurement is in principle required to find the center, resulting in /very fast center search. This approach was tested for the Ronchigram based aberration calculation method for aberration corrected scanning transmission electron microscopy. Both in simulation and in experiments, the center search was confirmed to work well although the convergence to find the best axis becomes slower with larger primary aberrations. Such aberration center determination is expected to fully automatize the aberration correction procedures, which used to require pre-alignment of experienced users. This approach is also applicable to automated aperture positioning. Copyright © 2013 Elsevier B.V. All rights reserved.

Laser line scan underwater imaging by complementary metal-oxide-semiconductor camera

NASA Astrophysics Data System (ADS)

He, Zhiyi; Luo, Meixing; Song, Xiyu; Wang, Dundong; He, Ning

2017-12-01

This work employs the complementary metal-oxide-semiconductor (CMOS) camera to acquire images in a scanning manner for laser line scan (LLS) underwater imaging to alleviate backscatter impact of seawater. Two operating features of the CMOS camera, namely the region of interest (ROI) and rolling shutter, can be utilized to perform image scan without the difficulty of translating the receiver above the target as the traditional LLS imaging systems have. By the dynamically reconfigurable ROI of an industrial CMOS camera, we evenly divided the image into five subareas along the pixel rows and then scanned them by changing the ROI region automatically under the synchronous illumination by the fun beams of the lasers. Another scanning method was explored by the rolling shutter operation of the CMOS camera. The fun beam lasers were turned on/off to illuminate the narrow zones on the target in a good correspondence to the exposure lines during the rolling procedure of the camera's electronic shutter. The frame synchronization between the image scan and the laser beam sweep may be achieved by either the strobe lighting output pulse or the external triggering pulse of the industrial camera. Comparison between the scanning and nonscanning images shows that contrast of the underwater image can be improved by our LLS imaging techniques, with higher stability and feasibility than the mechanically controlled scanning method.

Utilization of Additive Manufacturing for Aerospace Heat Exchangers

DTIC Science & Technology

2016-02-29

is made up of flat plates that are layered on top of each other creating air passages in between the plates where the hot liquid and cold liquid flow...electron beam- based) for two-dimensional scanning of the heat source on the powder layer , stages that decrease the build plate and increase the powder...build plate and result in uneven coating of subsequent powder layers or complete failure of the system to recoat. The perturbations in recoater

Quantitative in-situ scanning electron microscope pull-out experiments and molecular dynamics simulations of carbon nanotubes embedded in palladium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartmann, S., E-mail: steffen.hartmann@etit.tu-chemnitz.de; Blaudeck, T.; Hermann, S.

2014-04-14

In this paper, we present our results of experimental and numerical pull-out tests on carbon nanotubes (CNTs) embedded in palladium. We prepared simple specimens by employing standard silicon wafers, physical vapor deposition of palladium and deposition of CNTs with a simple drop coating technique. An AFM cantilever with known stiffness connected to a nanomanipulation system was utilized inside a scanning electron microscope (SEM) as a force sensor to determine forces acting on a CNT during the pull-out process. SEM-images of the cantilever attached to a CNT have been evaluated for subsequent displacement steps with greyscale correlation to determine the cantilevermore » deflection. We compare the experimentally obtained pull-out forces with values of numerical investigations by means of molecular dynamics and give interpretations for deviations according to material impurities or defects and their influence on the pull-out data. We find a very good agreement of force data from simulation and experiment, which is 17 nN and in the range of 10–61 nN, respectively. Our findings contribute to the ongoing research of the mechanical characterization of CNT-metal interfaces. This is of significant interest for the design of future mechanical sensors utilizing the intrinsic piezoresistive effect of CNTs or other future devices incorporating CNT-metal interfaces.« less

Use of fluorescence and scanning electron microscopy as tools in teaching biology

NASA Astrophysics Data System (ADS)

Ghosh, Nabarun; Silva, Jessica; Vazquez, Aracely; Das, A. B.; Smith, Don W.

2011-06-01

Recent nationwide surveys reveal significant decline in students' interest in Math and Sciences. The objective of this project was to inspire young minds in using various techniques involved in Sciences including Scanning Electron Microscopy. We used Scanning Electron Microscope in demonstrating various types of Biological samples. An SEM Tabletop model in the past decade has revolutionized the use of Scanning Electron Microscopes. Using SEM Tabletop model TM 1000 we studied biological specimens of fungal spores, pollen grains, diatoms, plant fibers, dust mites, insect parts and leaf surfaces. We also used fluorescence microscopy to view, to record and analyze various specimens with an Olympus BX40 microscope equipped with FITC and TRITC fluorescent filters, a mercury lamp source, DP-70 digital camera with Image Pro 6.0 software. Micrographs were captured using bright field microscopy, the fluoresceinisothiocyanate (FITC) filter, and the tetramethylrhodamine (TRITC) filter settings at 40X. A high pressure mercury lamp or UV source was used to excite the storage molecules or proteins which exhibited autofluorescence. We used fluorescent microscopy to confirm the localization of sugar beet viruses in plant organs by viewing the vascular bundles in the thin sections of the leaves and other tissues. We worked with the REU summer students on sample preparation and observation on various samples utilizing the SEM. Critical Point Drying (CPD) and metal coating with the sputter coater was followed before observing some cultured specimen and the samples that were soft in textures with high water content. SEM Top allowed investigating the detailed morphological features that can be used for classroom teaching. Undergraduate and graduate researchers studied biological samples of Arthropods, pollen grains and teeth collected from four species of snakes using SEM. This project inspired the research students to pursue their career in higher studies in science and 45% of the undergraduates participated in this project entered Graduate school.

Synchronized voltage contrast display analysis system

NASA Technical Reports Server (NTRS)

Johnston, M. F.; Shumka, A.; Miller, E.; Evans, K. C. (Inventor)

1982-01-01

An apparatus and method for comparing internal voltage potentials of first and second operating electronic components such as large scale integrated circuits (LSI's) in which voltage differentials are visually identified via an appropriate display means are described. More particularly, in a first embodiment of the invention a first and second scanning electron microscope (SEM) are configured to scan a first and second operating electronic component respectively. The scan pattern of the second SEM is synchronized to that of the first SEM so that both simultaneously scan corresponding portions of the two operating electronic components. Video signals from each SEM corresponding to secondary electron signals generated as a result of a primary electron beam intersecting each operating electronic component in accordance with a predetermined scan pattern are provided to a video mixer and color encoder.

Swept Line Electron Beam Annealing of Ion Implanted Semiconductors.

DTIC Science & Technology

1982-07-01

of my research to the mainstream of technology. The techniques used for beam processing are distinguished by their * ~.* beam source and method by...raster scanned CW lasers (CWL), pulsed ion beams (PI), area pulsed electron beams (PEE), raster scanned (RSEB) or multi - scanned electron beams (MSEB...where high quality or tailored profiles are required. Continuous wave lasers and multi -scanned or swept-line electron beams are the most likely candidates

Scanning Transmission Electron Microscopy | Materials Science | NREL

Science.gov Websites

mode by collecting the EDS and EELS signals point-by-point as one scans the electron probe across the . Examples of Scanning Transmission Electron Microscopy Capabilities Z-contrast image microphoto taken by

Application of environmental scanning electron microscopy to determine biological surface structure.

PubMed

Kirk, S E; Skepper, J N; Donald, A M

2009-02-01

The use of environmental scanning electron microscopy in biology is growing as more becomes understood about the advantages and limitations of the technique. These are discussed and we include new evidence about the effect of environmental scanning electron microscopy imaging on the viability of mammalian cells. We show that although specimen preparation for high-vacuum scanning electron microscopy introduces some artefacts, there are also challenges in the use of environmental scanning electron microscopy, particularly at higher resolutions. This suggests the two technologies are best used in combination. We have used human monocyte-derived macrophages as a test sample, imaging their complicated and delicate membrane ruffles and protrusions. We have also explored the possibility of using environmental scanning electron microscopy for dynamic experiments, finding that mammalian cells cannot be imaged and kept alive in the environmental scanning electron microscopy. The dehydration step in which the cell surface is exposed causes irreversible damage, probably via loss of membrane integrity during liquid removal in the specimen chamber. Therefore, mammalian cells should be imaged after fixation where possible to protect against damage as a result of chamber conditions.

Accurate Virus Quantitation Using a Scanning Transmission Electron Microscopy (STEM) Detector in a Scanning Electron Microscope

DTIC Science & Technology

2017-06-29

Accurate Virus Quantitation Using a Scanning Transmission Electron Microscopy (STEM) Detector in a Scanning Electron Microscope Candace D Blancett1...L Norris2, Cynthia A Rossi4 , Pamela J Glass3, Mei G Sun1,* 1 Pathology Division, United States Army Medical Research Institute of Infectious...Diseases (USAMRIID), 1425 Porter Street, Fort Detrick, Maryland, 21702 2Biostatistics Division, United States Army Medical Research Institute of

Electron probe X-ray microanalysis of cultured myogenic C2C12 cells with scanning and scanning transmission electron microscopy.

PubMed

Tylko, G; Karasiński, J; Wróblewski, R; Roomans, G M; Kilarski, W M

2000-01-01

Heterogeneity of the elemental content of myogenic C2C12 cultured cells was studied by electron probe X-ray microanalysis (EPXMA) with scanning (SEM EPXMA) and scanning transmission electron microscopy (STEM EPXMA). The best plastic substrate for growing cells was Thermanox. For STEM EPXMA, a Formvar film coated with carbon was found to be suitable substrate. The cells examined by scanning transmission electron microscopy showed great heterogeneity in their elemental content in comparison with the cells examined in the scanning electron microscope despite of an almost identical preparation procedure for EPXMA. Nevertheless the K/Na ratios obtained from both methods of EPXMA were very close (4.1 and 4.3). We conclude that the observed discrepancy in the elemental content obtained by the two methods may be due to differences in instrumentation and this must be taken into account when planning a comparative study.

Flow-induced immobilization of glucose oxidase in nonionic micellar nanogels for glucose sensing.

PubMed

Cardiel, Joshua J; Zhao, Ya; Tonggu, Lige; Wang, Liguo; Chung, Jae-Hyun; Shen, Amy Q

2014-10-21

A simple microfluidic platform was utilized to immobilize glucose oxidase (GOx) in a nonionic micellar scaffold. The immobilization of GOx was verified by using a combination of cryogenic electron microscopy (cryo-EM), scanning electron microscopy (SEM), and ultraviolet spectroscopy (UV) techniques. Chronoamperometric measurements were conducted on nanogel-GOx scaffolds under different glucose concentrations, exhibiting linear amperometric responses. Without impacting the lifetime and denaturation of GOx, the nonionic nanogel provides a favorable microenvironment for GOx in biological media. This flow-induced immobilization method in a nonionic nanogel host matrix opens up new pathways for designing a simple, fast, biocompatible, and cost-effective process to immobilize biomolecules that are averse to ionic environments.

Microstructures and properties of rapidly solidified alloys

NASA Technical Reports Server (NTRS)

Shechtman, D.; Horowitz, E.

1984-01-01

The microstructure and properties of rapidly solidified aluminum alloys were researched. The effects of powder and flake chemistry and morphology and alternative consolidation processing parameters are being conducted. Samples of the powders being utilized were obtained for comprehensive metallurgical characterization. Seven aluminum alloys in the form of thin foils were studied by a variety of techniques including optical metallography, scanning electron microscope, and transmission electron microscope. Details of the microstructural characteristics are presented along with a discussion of the solidification process. A better understanding of the microstructure of the rapidly solidified aluminum alloys prepared by a variety of techniques such as roller quenching, the vacuum atomized procedure, ultrasonically atomized in inert atmospheres, and atomized in flue gas was provided.

Imaging of endodontic biofilms by combined microscopy (FISH/cLSM - SEM).

PubMed

Schaudinn, C; Carr, G; Gorur, A; Jaramillo, D; Costerton, J W; Webster, P

2009-08-01

Scanning electron microscopy is a useful imaging approach for the visualization of bacterial biofilms in their natural environments including their medical and dental habitats, because it allows for the exploration of large surfaces with excellent resolution of topographic features. Most biofilms in nature, however, are embedded in a thick layer of extracellular matrix that prevents a clear identification of individual bacteria by scanning electron microscopy. The use of confocal laser scanning microscopy on the other hand in combination with fluorescence in situ hybridization enables the visualization of matrix embedded bacteria in multi-layered biofilms. In our study, fluorescence in situ hybridization/confocal laser scanning microscopy and scanning electron microscopy were applied to visualize bacterial biofilm in endodontic root canals. The resulting fluorescence in situ hybridization /confocal laser scanning microscopy and scanning electron microscopy and pictures were subsequently combined into one single image to provide high-resolution information on the location of hidden bacteria. The combined use of scanning electron microscopy and fluorescence in situ hybridization / confocal laser scanning microscopy has the potential to overcome the limits of each single technique.

TiO₂ Nanowire Networks Prepared by Titanium Corrosion and Their Application to Bendable Dye-Sensitized Solar Cells.

PubMed

Jin, Saera; Shin, Eunhye; Hong, Jongin

2017-10-12

TiO₂ nanowire networks were prepared, using the corrosion of Ti foils in alkaline (potassium hydroxide, KOH) solution at different temperatures, and then a further ion-exchange process. The prepared nanostructures were characterized by field emission scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The wet corroded foils were utilized as the photoanodes of bendable dye-sensitized solar cells (DSSCs), which exhibited a power conversion efficiency of 1.11% under back illumination.

Application of modern surface analytical tools in the investigation of surface deterioration processes

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1983-01-01

Surface profilometry and scanning electron microscopy were utilized to study changes in the surface of polymers when eroded. The X-ray photoelectron spectroscopy (XPS) and depth profile analysis indicate the corrosion of metal and ceramic surfaces and reveal the diffusion of certain species into the surface to produce a change in mechanical properties. Ion implantation, nitriding and plating and their effects on the surface are characterized. Auger spectroscopy analysis identified morphological properties of coatings applied to surfaces by sputter deposition.

Closed-Form Evaluation of Mutual Coupling in a Planar Array of Circular Apertures

NASA Technical Reports Server (NTRS)

Bailey, M. C.

1996-01-01

The integral expression for the mutual admittance between circular apertures in a planar array is evaluated in closed form. Very good accuracy is realized when compared with values that were obtained by numerical integration. Utilization of this closed-form expression, for all element pairs that are separated by more than one element spacing, yields extremely accurate results and significantly reduces the computation time that is required to analyze the performance of a large electronically scanning antenna array.

Sparse sampling and reconstruction for electron and scanning probe microscope imaging

DOEpatents

Anderson, Hyrum; Helms, Jovana; Wheeler, Jason W.; Larson, Kurt W.; Rohrer, Brandon R.

2015-07-28

Systems and methods for conducting electron or scanning probe microscopy are provided herein. In a general embodiment, the systems and methods for conducting electron or scanning probe microscopy with an undersampled data set include: driving an electron beam or probe to scan across a sample and visit a subset of pixel locations of the sample that are randomly or pseudo-randomly designated; determining actual pixel locations on the sample that are visited by the electron beam or probe; and processing data collected by detectors from the visits of the electron beam or probe at the actual pixel locations and recovering a reconstructed image of the sample.

Compact high-speed scanning lidar system

NASA Astrophysics Data System (ADS)

Dickinson, Cameron; Hussein, Marwan; Tripp, Jeff; Nimelman, Manny; Koujelev, Alexander

2012-06-01

The compact High Speed Scanning Lidar (HSSL) was designed to meet the requirements for a rover GN&C sensor. The eye-safe HSSL's fast scanning speed, low volume and low power, make it the ideal choice for a variety of real-time and non-real-time applications including: 3D Mapping; Vehicle guidance and Navigation; Obstacle Detection; Orbiter Rendezvous; Spacecraft Landing / Hazard Avoidance. The HSSL comprises two main hardware units: Sensor Head and Control Unit. In a rover application, the Sensor Head mounts on the top of the rover while the Control Unit can be mounted on the rover deck or within its avionics bay. An Operator Computer is used to command the lidar and immediately display the acquired scan data. The innovative lidar design concept was a result of an extensive trade study conducted during the initial phase of an exploration rover program. The lidar utilizes an innovative scanner coupled with a compact fiber laser and high-speed timing electronics. Compared to existing compact lidar systems, distinguishing features of the HSSL include its high accuracy, high resolution, high refresh rate and large field of view. Other benefits of this design include the capability to quickly configure scan settings to fit various operational modes.

Preparation and characterization of polyol assisted ultrafine Cu-Ni-Mg-Ca mixed ferrite via co-precipitation method

NASA Astrophysics Data System (ADS)

Boobalan, T.; Pavithradevi, S.; Suriyanarayanan, N.; Manivel Raja, M.; Ranjith Kumar, E.

2017-04-01

Nanocrystalline spinel ferrite of composition Cu0.2Ni0.2Mg0.2Ca0.4Fe2O4 is synthesized by wet hydroxyl co-precipitation method in ethylene glycol as chelating agent and sodium hydroxide as precipitator at pH 8. Ethylene glycol is utilized as the medium which serves as the dissolvable and in addition a complexing specialist. The synthesized particles are annealed at various temperatures. Thermogravimetric investigation affirms that at 280 °C ethylene glycol is dissipated totally and stable phase arrangement happens over 680 °C. FTIR spectra of as synthesized and annealed at 1050 °C recorded between 400 cm-1 and 4000 cm-1. Structural characterizations of all the samples are carried out by X-ray diffraction (XRD) technique. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) affirm that the particles are spherical and cubic shape with the crystallite size of 12 nm to 32 nm. Magnetic measurements are performed utilizing vibrating sample magnetometer at room temperature.

Microwave-Assisted Preparation of Activated Carbon from Eupatorium Adenophorum: Effects of Preparation Parameters

NASA Astrophysics Data System (ADS)

Cheng, Song; Zhang, Shengzhou; Zhang, Libo; Xia, Hongying; Peng, Jinhui; Wang, Shixing

2017-09-01

Eupatorium adenophorum, global exotic weeds, was utilized as feedstock for preparation of activated carbon (AC) via microwave-induced KOH activation. Influences of the three vital process parameters - microwave power, activation time and impregnation ratio (IR) - have been assessed on the adsorption capacity and yield of AC. The process parameters were optimized utilizing the Design Expert software and were identified to be a microwave power of 700 W, an activation time of 15 min and an IR of 4, with the resultant iodine adsorption number and yield being 2,621 mg/g and 28.25 %, respectively. The key parameters that characterize the AC such as the brunauer emmett teller (BET) surface area, total pore volume and average pore diameter were estimated to be 3,918 m2/g, 2,383 ml/g and 2.43 nm, respectively, under the optimized process conditions. The surface characteristics of AC were characterized by Fourier transform infrared spectroscopy, scanning electron microscope and Transmission electron microscope.

Dual passivation of intrinsic defects at the compound semiconductor/oxide interface using an oxidant and a reductant.

PubMed

Kent, Tyler; Chagarov, Evgeniy; Edmonds, Mary; Droopad, Ravi; Kummel, Andrew C

2015-05-26

Studies have shown that metal oxide semiconductor field-effect transistors fabricated utilizing compound semiconductors as the channel are limited in their electrical performance. This is attributed to imperfections at the semiconductor/oxide interface which cause electronic trap states, resulting in inefficient modulation of the Fermi level. The physical origin of these states is still debated mainly because of the difficulty in assigning a particular electronic state to a specific physical defect. To gain insight into the exact source of the electronic trap states, density functional theory was employed to model the intrinsic physical defects on the InGaAs (2 × 4) surface and to model the effective passivation of these defects by utilizing both an oxidant and a reductant to eliminate metallic bonds and dangling-bond-induced strain at the interface. Scanning tunneling microscopy and spectroscopy were employed to experimentally determine the physical and electronic defects and to verify the effectiveness of dual passivation with an oxidant and a reductant. While subsurface chemisorption of oxidants on compound semiconductor substrates can be detrimental, it has been shown theoretically and experimentally that oxidants are critical to removing metallic defects at oxide/compound semiconductor interfaces present in nanoscale channels, oxides, and other nanostructures.

Electronic and mechanical properties of graphene-germanium interfaces grown by chemical vapor deposition

DOE PAGES

Kiraly, Brian T.; Jacobberger, Robert M.; Mannix, Andrew J.; ...

2015-10-27

Epitaxially oriented wafer-scale graphene grown directly on semiconducting Ge substrates is of high interest for both fundamental science and electronic device applications. To date, however, this material system remains relatively unexplored structurally and electronically, particularly at the atomic scale. To further understand the nature of the interface between graphene and Ge, we utilize ultrahigh vacuum scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) along with Raman and X-ray photoelectron spectroscopy to probe interfacial atomic structure and chemistry. STS reveals significant differences in electronic interactions between graphene and Ge(110)/Ge(111), which is consistent with a model of stronger interaction on Ge(110)more » leading to epitaxial growth. Raman spectra indicate that the graphene is considerably strained after growth, with more point-to-point variation on Ge(111). Furthermore, this native strain influences the atomic structure of the interface by inducing metastable and previously unobserved Ge surface reconstructions following annealing. These nonequilibrium reconstructions cover >90% of the surface and, in turn, modify both the electronic and mechanical properties of the graphene overlayer. Finally, graphene on Ge(001) represents the extreme strain case, where graphene drives the reorganization of the Ge surface into [107] facets. From this study, it is clear that the interaction between graphene and the underlying Ge is not only dependent on the substrate crystallographic orientation, but is also tunable and strongly related to the atomic reconfiguration of the graphene–Ge interface.« less

Design and simulation of a 800 Mbit/s data link for magnetic resonance imaging wearables.

PubMed

Vogt, Christian; Buthe, Lars; Petti, Luisa; Cantarella, Giuseppe; Munzenrieder, Niko; Daus, Alwin; Troster, Gerhard

2015-08-01

This paper presents the optimization of electronic circuitry for operation in the harsh electro magnetic (EM) environment during a magnetic resonance imaging (MRI) scan. As demonstrator, a device small enough to be worn during the scan is optimized. Based on finite element method (FEM) simulations, the induced current densities due to magnetic field changes of 200 T s(-1) were reduced from 1 × 10(10) A m(-2) by one order of magnitude, predicting error-free operation of the 1.8V logic employed. The simulations were validated using a bit error rate test, which showed no bit errors during a MRI scan sequence. Therefore, neither the logic, nor the utilized 800 Mbit s(-1) low voltage differential swing (LVDS) data link of the optimized wearable device were significantly influenced by the EM interference. Next, the influence of ferro-magnetic components on the static magnetic field and consequently the image quality was simulated showing a MRI image loss with approximately 2 cm radius around a commercial integrated circuit of 1×1 cm(2). This was successively validated by a conventional MRI scan.

Scanning ultrafast electron microscopy.

PubMed

Yang, Ding-Shyue; Mohammed, Omar F; Zewail, Ahmed H

2010-08-24

Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for which the pulse contains at most one or a few electrons, thus achieving imaging without the space-charge effect between electrons, and still in ten(s) of seconds. For imaging, the secondary electrons from surface structures are detected, as demonstrated here for material surfaces and biological specimens. By recording backscattered electrons, diffraction patterns from single crystals were also obtained. Scanning pulsed-electron microscopy with the acquired spatiotemporal resolutions, and its efficient heat-dissipation feature, is now poised to provide in situ 4D imaging and with environmental capability.

Atom Optics for Bose-Einstein Condensates (BEC)

DTIC Science & Technology

2012-04-25

Electron Micrograph of the Top View of Test Chip A .......................................29 11. A Scanning Electron Micrograph of the Cross...Sectional View of Test Chip A .....................29 12. A Scanning Electron Micrograph of the Top View of Test Chip B...30 13. A Scanning Electron Micrograph of the Cross Sectional View of Test Chip B .....................30 14. Toner Masks for Etching

Data mining graphene: Correlative analysis of structure and electronic degrees of freedom in graphenic monolayers with defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ziatdinov, Maxim A.; Fujii, Shintaro; Kiguchi, Manabu

The link between changes in the material crystal structure and its mechanical, electronic, magnetic, and optical functionalities known as the structure-property relationship is the cornerstone of the contemporary materials science research. The recent advances in scanning transmission electron and scanning probe microscopies (STEM and SPM) have opened an unprecedented path towards examining the materials structure property relationships on the single-impurity and atomic-configuration levels. Lacking, however, are the statistics-based approaches for cross-correlation of structure and property variables obtained in different information channels of the STEM and SPM experiments. Here we have designed an approach based on a combination of sliding windowmore » Fast Fourier Transform, Pearson correlation matrix, linear and kernel canonical correlation, to study a relationship between lattice distortions and electron scattering from the SPM data on graphene with defects. Our analysis revealed that the strength of coupling to strain is altered between different scattering channels which can explain coexistence of several quasiparticle interference patterns in the nanoscale regions of interest. In addition, the application of the kernel functions allowed us extracting a non-linear component of the relationship between the lattice strain and scattering intensity in graphene. Lastly, the outlined approach can be further utilized to analyzing correlations in various multi-modal imaging techniques where the information of interest is spatially distributed and has usually a complex multidimensional nature.« less

Data mining graphene: Correlative analysis of structure and electronic degrees of freedom in graphenic monolayers with defects

DOE PAGES

Ziatdinov, Maxim A.; Fujii, Shintaro; Kiguchi, Manabu; ...

2016-11-09

The link between changes in the material crystal structure and its mechanical, electronic, magnetic, and optical functionalities known as the structure-property relationship is the cornerstone of the contemporary materials science research. The recent advances in scanning transmission electron and scanning probe microscopies (STEM and SPM) have opened an unprecedented path towards examining the materials structure property relationships on the single-impurity and atomic-configuration levels. Lacking, however, are the statistics-based approaches for cross-correlation of structure and property variables obtained in different information channels of the STEM and SPM experiments. Here we have designed an approach based on a combination of sliding windowmore » Fast Fourier Transform, Pearson correlation matrix, linear and kernel canonical correlation, to study a relationship between lattice distortions and electron scattering from the SPM data on graphene with defects. Our analysis revealed that the strength of coupling to strain is altered between different scattering channels which can explain coexistence of several quasiparticle interference patterns in the nanoscale regions of interest. In addition, the application of the kernel functions allowed us extracting a non-linear component of the relationship between the lattice strain and scattering intensity in graphene. Lastly, the outlined approach can be further utilized to analyzing correlations in various multi-modal imaging techniques where the information of interest is spatially distributed and has usually a complex multidimensional nature.« less

Measurement of minority-carrier drift mobility in solar cells using a modulated electron beam

NASA Technical Reports Server (NTRS)

Othmer, S.; Hopkins, M. A.

1980-01-01

A determination of diffusivity on solar cells is here reported which utilizes a one dimensional treatment of diffusion under sinusoidal excitation. An intensity-modulated beam of a scanning electron microscope was used as a source of excitation. The beam was injected into the rear of the cell, and the modulated component of the induced terminal current was recovered phase sensitively. A Faraday cup to measure the modulated component of beam current was mounted next to the sample, and connected to the same electronics. A step up transformer and preamplifier were mounted on the sample holder. Beam currents on the order of 400-pA were used in order to minimize effects of high injection. The beam voltage was 34-kV, and the cell bias was kept at 0-V.

Method and apparatus for a high-resolution three dimensional confocal scanning transmission electron microscope

DOEpatents

de Jonge, Niels [Oak Ridge, TN

2010-08-17

A confocal scanning transmission electron microscope which includes an electron illumination device providing an incident electron beam propagating in a direction defining a propagation axis, and a precision specimen scanning stage positioned along the propagation axis and movable in at least one direction transverse to the propagation axis. The precision specimen scanning stage is configured for positioning a specimen relative to the incident electron beam. A projector lens receives a transmitted electron beam transmitted through at least part of the specimen and focuses this transmitted beam onto an image plane, where the transmitted beam results from the specimen being illuminated by the incident electron beam. A detection system is placed approximately in the image plane.

Development of scanning holographic display using MEMS SLM

NASA Astrophysics Data System (ADS)

Takaki, Yasuhiro

2016-10-01

Holography is an ideal three-dimensional (3D) display technique, because it produces 3D images that naturally satisfy human 3D perception including physiological and psychological factors. However, its electronic implementation is quite challenging because ultra-high resolution is required for display devices to provide sufficient screen size and viewing zone. We have developed holographic display techniques to enlarge the screen size and the viewing zone by use of microelectromechanical systems spatial light modulators (MEMS-SLMs). Because MEMS-SLMs can generate hologram patterns at a high frame rate, the time-multiplexing technique is utilized to virtually increase the resolution. Three kinds of scanning systems have been combined with MEMS-SLMs; the screen scanning system, the viewing-zone scanning system, and the 360-degree scanning system. The screen scanning system reduces the hologram size to enlarge the viewing zone and the reduced hologram patterns are scanned on the screen to increase the screen size: the color display system with a screen size of 6.2 in. and a viewing zone angle of 11° was demonstrated. The viewing-zone scanning system increases the screen size and the reduced viewing zone is scanned to enlarge the viewing zone: a screen size of 2.0 in. and a viewing zone angle of 40° were achieved. The two-channel system increased the screen size to 7.4 in. The 360-degree scanning increases the screen size and the reduced viewing zone is scanned circularly: the display system having a flat screen with a diameter of 100 mm was demonstrated, which generates 3D images viewed from any direction around the flat screen.

Bacteria interface pickering emulsions stabilized by self-assembled bacteria-chitosan network.

PubMed

Wongkongkatep, Pravit; Manopwisedjaroen, Khajohnpong; Tiposoth, Perapon; Archakunakorn, Somwit; Pongtharangkul, Thunyarat; Suphantharika, Manop; Honda, Kohsuke; Hamachi, Itaru; Wongkongkatep, Jirarut

2012-04-03

An oil-in-water Pickering emulsion stabilized by biobased material based on a bacteria-chitosan network (BCN) was developed for the first time in this study. The formation of self-assembled BCN was possible due to the electrostatic interaction between negatively charged bacterial cells and polycationic chitosan. The BCN was proven to stabilize the tetradecane/water interface, promoting formation of highly stable oil-in-water emulsion (o/w emulsion). We characterized and visualized the BCN stabilized o/w emulsions by scanning electron microscopy (SEM) and laser scanning confocal microscopy (LSCM). Due to the sustainability and low environmental impact of chitosan, the BCN-based emulsions open up opportunities for the development of an environmental friendly new interface material as well as the novel type of microreactor utilizing bacterial cells network.

EBSD and TEM characterization of high burn-up mixed oxide fuel

NASA Astrophysics Data System (ADS)

Teague, Melissa; Gorman, Brian; Miller, Brandon; King, Jeffrey

2014-01-01

Understanding and studying the irradiation behavior of high burn-up oxide fuel is critical to licensing of future fast breeder reactors. Advancements in experimental techniques and equipment are allowing for new insights into previously irradiated samples. In this work dual column focused ion beam (FIB)/scanning electron microscope (SEM) was utilized to prepared transmission electron microscope samples from mixed oxide fuel with a burn-up of 6.7% FIMA. Utilizing the FIB/SEM for preparation resulted in samples with a dose rate of <0.5 mRem/h compared to ∼1.1 R/h for a traditionally prepared TEM sample. The TEM analysis showed that the sample taken from the cooler rim region of the fuel pellet had ∼2.5× higher dislocation density than that of the sample taken from the mid-radius due to the lower irradiation temperature of the rim. The dual column FIB/SEM was additionally used to prepared and serially slice ∼25 μm cubes. High quality electron back scatter diffraction (EBSD) were collected from the face at each step, showing, for the first time, the ability to obtain EBSD data from high activity irradiated fuel.

Extracting the Bosonic Spectra of Pb Using Superconducting-Tip STS and Comparing it with the Cuprates

NASA Astrophysics Data System (ADS)

Niestemski, F. C.; Johnston, S.; Contryman, A. W.; Camp, C. D.; Devereaux, T. P.; Manoharan, H. C.

2012-02-01

In high-temperature superconductors the meaning of the common feature labeled ``peak-dip-hump'' is still a point of great debate. In terms of scanning tunneling spectroscopy (STS) this refers to the shape of satellite features that occur outside the coherence peaks in the dI/dV spectra. There are many conflicting interpretations and labeling schemes for this feature in both the hole- and electron-doped cuprates. The path to resolving this confusion is to study a well-understood BCS superconductor to better observe the way that the STM measures bosonic information. Utilizing the ultra-low electronic noise of our home-built low-temperature STM, and utilizing a superconducting tip for increased spectral resolution, we recreate the original McMillan and Rowell S-I-S junctionootnotetextW. L. McMillan and J. M. Rowell Phys. Rev. Lett., 14, 108-112 (1965) with the STM equivalent (S-Vacuum-S). This method provides very high energy resolution for both the filled and empty electronic states in both the superconducting and normal state. We compare this data to first-principle Eliashberg calculations and relate this data to ``peak-dip-hump'' in the high Tc case.

EBSD and TEM Characterization of High Burn-up Mixed Oxide Fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Teague, Melissa C.; Gorman, Brian P.; Miller, Brandon D.

2014-01-01

Understanding and studying the irradiation behavior of high burn-up oxide fuel is critical to licensing of future fast breeder reactors. Advancements in experimental techniques and equipment are allowing for new insights into previously irradiated samples. In this work dual column focused ion beam (FIB)/scanning electron microscope (SEM) was utilized to prepared transmission electron microscope samples from mixed oxide fuel with a burn-up of 6.7% FIMA. Utilizing the FIB/SEM for preparation resulted in samples with a dose rate of <0.5 mRem/h compared to approximately 1.1 R/h for a traditionally prepared TEM sample. The TEM analysis showed that the sample taken frommore » the cooler rim region of the fuel pellet had approximately 2.5x higher dislocation density than that of the sample taken from the mid-radius due to the lower irradiation temperature of the rim. The dual column FIB/SEM was additionally used to prepared and serially slice approximately 25 um cubes. High quality electron back scatter diffraction (EBSD) were collected from the face at each step, showing, for the first time, the ability to obtain EBSD data from high activity irradiated fuel.« less

Development of a fast framing detector for electron microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Ian J.; Bustillo, Karen C.; Ciston, Jim

2016-10-01

A high frame rate detector system is described that enables fast real-time data analysis of scanning diffraction experiments in scanning transmission electron microscopy (STEM). This is an end-to-end development that encompasses the data producing detector, data transportation, and real-time processing of data. The detector will consist of a central pixel sensor that is surrounded by annular silicon diodes. Both components of the detector system will synchronously capture data at almost 100 kHz frame rate, which produces an approximately 400 Gb/s data stream. Low-level preprocessing will be implemented in firmware before the data is streamed from the National Center for Electronmore » Microscopy (NCEM) to the National Energy Research Scientific Computing Center (NERSC). Live data processing, before it lands on disk, will happen on the Cori supercomputer and aims to present scientists with prompt experimental feedback. This online analysis will provide rough information of the sample that can be utilized for sample alignment, sample monitoring and verification that the experiment is set up correctly. Only a compressed version of the relevant data is then selected for more in-depth processing.« less

Biocompatibility enhancement of rare earth magnesium alloy by laser surface processing

NASA Astrophysics Data System (ADS)

Nie, Shilin; Wang, Yuqing; Liu, Haifeng; Guan, Yingchun

2018-01-01

Although magnesium and magnesium alloys are considered biocompatible and biodegradable, insufficient biocompatibility in body fluid environment is still the major drawback of magnesium alloys for their successful applications as biodegradable orthopaedic implants. In this work, magnesium alloy surface with both enhanced corrosion resistance and better cell adhesion property was directly fabricated by laser surface processing. Laser surface melting was used to improve corrosion resistance of Mg-6Gd-0.6Ca alloy. After laser surface melting, laser surface texturing was utilized on melted surface for better cell adhesion property. The corrosion resistance of laser-treated and as-received samples were evaluated using electrochemical technique. The effect of laser surface treatment on phase and microstructure evolution was evaluated using scanning electron microscopy, optical microscopy and X-ray diffraction. This work investigated the effect of laser treatment on cell distribution across the surface of magnesium alloy substrates. Osteoblast was cultured on the laser-treated surface and as-received surface. Cell morphology was observed with a scanning electron microscopy, and cell viability was evaluated by optical density measurement.

A simple method for detection of gunshot residue particles from hands, hair, face, and clothing using scanning electron microscopy/wavelength dispersive X-ray (SEM/WDX).

PubMed

Kage, S; Kudo, K; Kaizoji, A; Ryumoto, J; Ikeda, H; Ikeda, N

2001-07-01

We devised a simple and rapid method for detection of gunshot residue (GSR) particles, using scanning electron microscopy/wavelength dispersive X-ray (SEM/WDX) analysis. Experiments were done on samples containing GSR particles obtained from hands, hair, face, and clothing, using double-sided adhesive coated aluminum stubs (tape-lift method). SEM/WDX analyses for GSR were carried out in three steps: the first step was map analysis for barium (Ba) to search for GSR particles from lead styphnate primed ammunition, or tin (Sn) to search for GSR particles from mercury fulminate primed ammunition. The second step was determination of the location of GSR particles by X-ray imaging of Ba or Sn at a magnification of x 1000-2000 in the SEM, using data of map analysis, and the third step was identification of GSR particles, using WDX spectrometers. Analysis of samples from each primer of a stub took about 3 h. Practical applications were shown for utility of this method.

Atmospheric scanning electron microscope observes cells and tissues in open medium through silicon nitride film.

PubMed

Nishiyama, Hidetoshi; Suga, Mitsuo; Ogura, Toshihiko; Maruyama, Yuusuke; Koizumi, Mitsuru; Mio, Kazuhiro; Kitamura, Shinichi; Sato, Chikara

2010-03-01

Direct observation of subcellular structures and their characterization is essential for understanding their physiological functions. To observe them in open environment, we have developed an inverted scanning electron microscope with a detachable, open-culture dish, capable of 8 nm resolution, and combined with a fluorescence microscope quasi-simultaneously observing the same area from the top. For scanning electron microscopy from the bottom, a silicon nitride film window in the base of the dish maintains a vacuum between electron gun and open sample dish while allowing electrons to pass through. Electrons are backscattered from the sample and captured by a detector under the dish. Cells cultured on the open dish can be externally manipulated under optical microscopy, fixed, and observed using scanning electron microscopy. Once fine structures have been revealed by scanning electron microscopy, their component proteins may be identified by comparison with separately prepared fluorescence-labeled optical microscopic images of the candidate proteins, with their heavy-metal-labeled or stained ASEM images. Furthermore, cell nuclei in a tissue block stained with platinum-blue were successfully observed without thin-sectioning, which suggests the applicability of this inverted scanning electron microscope to cancer diagnosis. This microscope visualizes mesoscopic-scale structures, and is also applicable to non-bioscience fields including polymer chemistry. (c) 2010 Elsevier Inc. All rights reserved.

Transmission Kikuchi diffraction and transmission electron forescatter imaging of electropolished and FIB manufactured TEM specimens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zieliński, W., E-mail: wiziel@inmat.pw.edu.pl; Płociński, T.; Kurzydłowski, K.J.

2015-06-15

We present a study of the efficiency of the utility of scanning electron microscope (SEM)-based transmission methods for characterizing grain structure in thinned bulk metals. Foils of type 316 stainless steel were prepared by two methods commonly used for transmission electron microscopy — double-jet electropolishing and focused ion beam milling. A customized holder allowed positioning of the foils in a configuration appropriate for both transmission electron forward scatter diffraction, and for transmission imaging by the use of a forescatter detector with two diodes. We found that both crystallographic orientation maps and dark-field transmitted images could be obtained for specimens preparedmore » by either method. However, for both methods, preparation-induced artifacts may affect the quality or accuracy of transmission SEM data, especially those acquired by the use of transmission Kikuchi diffraction. Generally, the quality of orientation data was better for specimens prepared by electropolishing, due to the absence of ion-induced damage. - Highlights: • The transmission imaging and diffraction techniques are emerging in scanning electron microscopy (SEM) as promising new field of materials characterization. • The manuscript titled: “Transmission Kikuchi Diffraction and Transmission Electron Forescatter Imaging of Electropolished and FIB Manufactured TEM Specimens” documents how different specimen thinning procedures can effect efficiency of transmission Kikuchi diffraction and transmission electron forescatter imaging. • The abilities to make precision crystallographic orientation maps and dark-field images in transmission was studied on electropolished versus focus ion beam manufactured TEM specimens. • Depending on the need, electropolished and focused ion beam technique may produce suitable specimens for transmission imaging and diffraction in SEM.« less

Disruption of methicillin-resistant Staphylococcus aureus protein synthesis by tannins

PubMed Central

Adnan, Siti-Noor-Adnalizawati; Ibrahim, Nazlina; Yaacob, Wan Ahmad

2017-01-01

Introduction Methicillin-resistant Staphylococcus aureus (MRSA) is a worldwide public health threat, displaying multiple antibiotic resistance that causes morbidity and mortality. Management of multidrug-resistant (MDR) MRSA infections is extremely difficult due to their inherent resistance to currently used antibiotics. New antibiotics are needed to combat the emergence of antimicrobial resistance. Methods The in vitro effect of tannins was studied against MRSA reference strain (ATCC 43300) and MRSA clinical strains utilizing antimicrobial assays in conjunction with both scanning and transmission electron microscopy. To reveal the influence of tannins in MRSA protein synthesis disruption, we utilized next-generation sequencing (NGS) to provide further insight into the novel protein synthesis transcriptional response of MRSA exposed to these compounds. Results Tannins possessed both bacteriostatic and bactericidal activity with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 0.78 and 1.56 mg/mL, respectively, against all tested MRSA. Scanning and transmission electron microscopy of MRSA treated with tannins showed decrease in cellular volume, indicating disruption of protein synthesis. Conclusion Analysis of a genome-wide transcriptional profile of the reference strain ATCC 43300 MRSA in response to tannins has led to the finding that tannins induced significant modulation in essential ribosome pathways, which caused a reduction in the translation processes that lead to inhibition of protein synthesis and obviation of bacterial growth. These findings highlight the potential of tannins as new promising anti-MRSA agents in clinical application such as body wash and topical cream or ointments. PMID:29264356

Preparation of porous palladium nanowire arrays and their catalytic performance for hydrogen peroxide electroreduction in acid medium

NASA Astrophysics Data System (ADS)

Wang, Xin; Ye, Ke; Gao, Yinyi; Zhang, Hongyu; Cheng, Kui; Xiao, Xue; Wang, Guiling; Cao, Dianxue

2016-01-01

Nanoporous palladium supported on the carbon coated titanium carbide (C@TiC) nanowire arrays (Pd NP/C@TiC) are successfully prepared by a facile chemical vapor deposition of three-dimensional (3D) C@TiC substrate, followed by electrochemical codeposition of Pd-Ni and removal of Ni via dealloying. The structure and morphology of the obtained Pd NP/C@TiC electrodes are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) are used to examine the catalytic performances of the electrodes for H2O2 electroreduction in H2SO4 solution. The Pd NP/C@TiC electrode exhibits a largely effective specific surface area owing to its open nanoporous structure allowing the full utilization of Pd surface active sites. At the potential of 0.2 V in 2.0 mol L-1 H2O2 and 2 mol L-1 H2SO4 solutions, the reduction current density reaches 3.47 A mg-1, which is significantly higher than the catalytic activity of H2O2 electroreduction achieved previously with precious metals as catalysts.

Full cycle rapid scan EPR deconvolution algorithm.

PubMed

Tseytlin, Mark

2017-08-01

Rapid scan electron paramagnetic resonance (RS EPR) is a continuous-wave (CW) method that combines narrowband excitation and broadband detection. Sinusoidal magnetic field scans that span the entire EPR spectrum cause electron spin excitations twice during the scan period. Periodic transient RS signals are digitized and time-averaged. Deconvolution of absorption spectrum from the measured full-cycle signal is an ill-posed problem that does not have a stable solution because the magnetic field passes the same EPR line twice per sinusoidal scan during up- and down-field passages. As a result, RS signals consist of two contributions that need to be separated and postprocessed individually. Deconvolution of either of the contributions is a well-posed problem that has a stable solution. The current version of the RS EPR algorithm solves the separation problem by cutting the full-scan signal into two half-period pieces. This imposes a constraint on the experiment; the EPR signal must completely decay by the end of each half-scan in order to not be truncated. The constraint limits the maximum scan frequency and, therefore, the RS signal-to-noise gain. Faster scans permit the use of higher excitation powers without saturating the spin system, translating into a higher EPR sensitivity. A stable, full-scan algorithm is described in this paper that does not require truncation of the periodic response. This algorithm utilizes the additive property of linear systems: the response to a sum of two inputs is equal the sum of responses to each of the inputs separately. Based on this property, the mathematical model for CW RS EPR can be replaced by that of a sum of two independent full-cycle pulsed field-modulated experiments. In each of these experiments, the excitation power equals to zero during either up- or down-field scan. The full-cycle algorithm permits approaching the upper theoretical scan frequency limit; the transient spin system response must decay within the scan period. Separation of the interfering up- and down-field scan responses remains a challenge for reaching the full potential of this new method. For this reason, only a factor of two increase in the scan rate was achieved, in comparison with the standard half-scan RS EPR algorithm. It is important for practical use that faster scans not necessarily increase the signal bandwidth because acceleration of the Larmor frequency driven by the changing magnetic field changes its sign after passing the inflection points on the scan. The half-scan and full-scan algorithms are compared using a LiNC-BuO spin probe of known line-shape, demonstrating that the new method produces stable solutions when RS signals do not completely decay by the end of each half-scan. Copyright © 2017 Elsevier Inc. All rights reserved.

Full cycle rapid scan EPR deconvolution algorithm

NASA Astrophysics Data System (ADS)

Tseytlin, Mark

2017-08-01

Rapid scan electron paramagnetic resonance (RS EPR) is a continuous-wave (CW) method that combines narrowband excitation and broadband detection. Sinusoidal magnetic field scans that span the entire EPR spectrum cause electron spin excitations twice during the scan period. Periodic transient RS signals are digitized and time-averaged. Deconvolution of absorption spectrum from the measured full-cycle signal is an ill-posed problem that does not have a stable solution because the magnetic field passes the same EPR line twice per sinusoidal scan during up- and down-field passages. As a result, RS signals consist of two contributions that need to be separated and postprocessed individually. Deconvolution of either of the contributions is a well-posed problem that has a stable solution. The current version of the RS EPR algorithm solves the separation problem by cutting the full-scan signal into two half-period pieces. This imposes a constraint on the experiment; the EPR signal must completely decay by the end of each half-scan in order to not be truncated. The constraint limits the maximum scan frequency and, therefore, the RS signal-to-noise gain. Faster scans permit the use of higher excitation powers without saturating the spin system, translating into a higher EPR sensitivity. A stable, full-scan algorithm is described in this paper that does not require truncation of the periodic response. This algorithm utilizes the additive property of linear systems: the response to a sum of two inputs is equal the sum of responses to each of the inputs separately. Based on this property, the mathematical model for CW RS EPR can be replaced by that of a sum of two independent full-cycle pulsed field-modulated experiments. In each of these experiments, the excitation power equals to zero during either up- or down-field scan. The full-cycle algorithm permits approaching the upper theoretical scan frequency limit; the transient spin system response must decay within the scan period. Separation of the interfering up- and down-field scan responses remains a challenge for reaching the full potential of this new method. For this reason, only a factor of two increase in the scan rate was achieved, in comparison with the standard half-scan RS EPR algorithm. It is important for practical use that faster scans not necessarily increase the signal bandwidth because acceleration of the Larmor frequency driven by the changing magnetic field changes its sign after passing the inflection points on the scan. The half-scan and full-scan algorithms are compared using a LiNC-BuO spin probe of known line-shape, demonstrating that the new method produces stable solutions when RS signals do not completely decay by the end of each half-scan.

Electronic noise in CT detectors: Impact on image noise and artifacts.

PubMed

Duan, Xinhui; Wang, Jia; Leng, Shuai; Schmidt, Bernhard; Allmendinger, Thomas; Grant, Katharine; Flohr, Thomas; McCollough, Cynthia H

2013-10-01

The objective of our study was to evaluate in phantoms the differences in CT image noise and artifact level between two types of commercial CT detectors: one with distributed electronics (conventional) and one with integrated electronics intended to decrease system electronic noise. Cylindric water phantoms of 20, 30, and 40 cm in diameter were scanned using two CT scanners, one equipped with integrated detector electronics and one with distributed detector electronics. All other scanning parameters were identical. Scans were acquired at four tube potentials and 10 tube currents. Semianthropomorphic phantoms were scanned to mimic the shoulder and abdominal regions. Images of two patients were also selected to show the clinical values of the integrated detector. Reduction of image noise with the integrated detector depended on phantom size, tube potential, and tube current. Scans that had low detected signal had the greatest reductions in noise, up to 40% for a 30-cm phantom scanned using 80 kV. This noise reduction translated into up to 50% in dose reduction to achieve equivalent image noise. Streak artifacts through regions of high attenuation were reduced by up to 45% on scans obtained using the integrated detector. Patient images also showed superior image quality for the integrated detector. For the same applied radiation level, the use of integrated electronics in a CT detector showed a substantially reduced level of electronic noise, resulting in reductions in image noise and artifacts, compared with detectors having distributed electronics.

Utilizing the M-Scan to Measure Standards-Based Mathematics Teaching Practices: Affordances and Limitations

ERIC Educational Resources Information Center

Walkowiak, Temple A.; Berry, Robert Q.; Pinter, Holly H.; Jacobson, Erik D.

2018-01-01

The Mathematics Scan (M-Scan), a content-specific observational measure, was utilized to examine the extent to which "standards-based mathematics teaching practices" were present in three focal lessons. While previous studies have provided evidence of validity of the inferences drawn from M-Scan data, no prior work has investigated the…

Scanning ultrafast electron microscopy

PubMed Central

Yang, Ding-Shyue; Mohammed, Omar F.; Zewail, Ahmed H.

2010-01-01

Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for which the pulse contains at most one or a few electrons, thus achieving imaging without the space-charge effect between electrons, and still in ten(s) of seconds. For imaging, the secondary electrons from surface structures are detected, as demonstrated here for material surfaces and biological specimens. By recording backscattered electrons, diffraction patterns from single crystals were also obtained. Scanning pulsed-electron microscopy with the acquired spatiotemporal resolutions, and its efficient heat-dissipation feature, is now poised to provide in situ 4D imaging and with environmental capability. PMID:20696933

Materials Characterization of Electron Beam Melted Ti-6Al-4V

NASA Technical Reports Server (NTRS)

Draper, Susan; Lerch, Brad; Rogers, Richard; Martin, Richard; Locci, Ivan; Garg, Anita

2015-01-01

An in-depth material characterization of Electron Beam Melted (EBM) Ti-6Al-4V material has been completed. Hot Isostatic Pressing (HIP) was utilized to close porosity from fabrication and also served as a material heat treatment to obtain the desired microstructure. The changes in the microstructure and chemistry from the powder to pre-HIP and post-HIP material have been analyzed. Computed tomography (CT) scans indicated porosity closure during HIP and high-density inclusions scattered throughout the specimens. The results of tensile and high cycle fatigue (HCF) testing are compared to conventional Ti-6Al-4V. The EBM Ti-6Al-4V had similar or superior mechanical properties compared to conventionally manufactured Ti-6Al-4V.

SRB seawater corrosion project

NASA Technical Reports Server (NTRS)

Bozack, M. J.

1991-01-01

The corrosion behavior of 2219 aluminum when exposed to seawater was characterized. Controlled corrosion experiments at three different temperatures (30, 60 and 100 C) and two different environments (seawater and 3.5 percent salt solution) were designed to elucidate the initial stages in the corrosion process. It was found that 2219 aluminum is an active catalytic surface for growth of Al2O3, NaCl, and MgO. Formation of Al2O3 is favored at lower temperatures, while MgO is favored at higher temperatures. Visible corrosion products are formed within 30 minutes after seawater exposure. Corrosion characteristics in 3.5 percent salt solution are different than corrosion in seawater. Techniques utilized were: (1) scanning electron microscopy, (2) energy dispersive x-ray spectroscopy, and (3) Auger electron spectroscopy.

Scanning electron microscopy of hepatic ultrastructure: secondary, backscattered, and transmitted electron imaging.

PubMed

Miyai, K; Abraham, J L; Linthicum, D S; Wagner, R M

1976-10-01

Several methods of tissue preparation and different modes of operation of the scanning electron microscope were used to study the ultrastructure of rat liver. Rat livers were perfusion fixed with buffered 2 per cent paraformaldehyde or a mixture of 1.5 per cent paraformaldehyde and 1 per cent glutaraldehyde and processed as follows. Tissue blocks were postfixed in buffered 2 per cent osmium tetroxide followed sequentially by the ligand-mediated osmium binding technique, dehydration and cryofracture in ethanol, and critical point drying. They were then examined without metal coating in the scanning electron microscope operating in the secondary electron and backscattered electron modes. Fifty-micrometer sections were cut with a tissue sectioner, stained with lead citrate, postfixed with osmium, dehydrated, critical point dried, and examined in the secondary electron and back-scattered electron modes. Frozen sections (0.25 to 0.75 mum. thick) were cut by the method of Tokuyasu (Toluyasu KT: J Cell Biol 57:551, 1973) and their scanning transmission electron microscope images were examined either with a scanning transmission electron microscope detector or with a conversion stub using the secondary electron detector. Secondary electron images of the liver prepared by ligand-mediated osmium binding and subsequent cryofracture revealed such intracellular structures as cisternae of the endoplasmic reticulum, lysosomes, mitochondria, lipid droplets, nucleolus and nuclear chromatin, as well as the usual surface morphology, Lipocytes in the perisinusoidal space were readily identified. Backscattered electron images. Unembedded frozen sections had little drying artifact and were virtually free of freezing damage. The scanning transmission electron microscope image revealed those organelles visualized by the secondary electron mode in the ligand-mediated osmium binding-treated tissue.

Laser scanning endoscope for diagnostic medicine

NASA Astrophysics Data System (ADS)

Ouimette, Donald R.; Nudelman, Sol; Spackman, Thomas; Zaccheo, Scott

1990-07-01

A new type of endoscope is being developed which utilizes an optical raster scanning system for imaging through an endoscope. The optical raster scanner utilizes a high speed, multifaceted, rotating polygon mirror system for horizontal deflection, and a slower speed galvanometer driven mirror as the vertical deflection system. When used in combination, the optical raster scanner traces out a raster similar to an electron beam raster used in television systems. This flying spot of light can then be detected by various types of photosensitive detectors to generate a video image of the surface or scene being illuminated by the scanning beam. The optical raster scanner has been coupled to an endoscope. The raster is projected down the endoscope, thereby illuminating the object to be imaged at the distal end of the endoscope. Elemental photodetectors are placed at the distal or proximal end of the endoscope to detect the reflected illumination from the flying spot of light. This time sequenced signal is captured by an image processor for display and processing. This technique offers the possibility for very small diameter endoscopes since illumination channel requirements are eliminated. Using various lasers, very specific spectral selectivity can be achieved to optimum contrast of specific lesions of interest. Using several laser lines, or a white light source, with detectors of specific spectral response, multiple spectrally selected images can be acquired simultaneously. The potential for co-linear therapy delivery while imaging is also possible.

Characterization of two-dimensional hexagonal boron nitride using scanning electron and scanning helium ion microscopy

NASA Astrophysics Data System (ADS)

Guo, Hongxuan; Gao, Jianhua; Ishida, Nobuyuki; Xu, Mingsheng; Fujita, Daisuke

2014-01-01

Characterization of the structural and physical properties of two-dimensional (2D) materials, such as layer number and inelastic mean free path measurements, is very important to optimize their synthesis and application. In this study, we characterize the layer number and morphology of hexagonal boron nitride (h-BN) nanosheets on a metallic substrate using field emission scanning electron microscopy (FE-SEM) and scanning helium ion microscopy (HIM). Using scanning beams of various energies, we could analyze the dependence of the intensities of secondary electrons on the thickness of the h-BN nanosheets. Based on the interaction between the scanning particles (electrons and helium ions) and h-BN nanosheets, we deduced an exponential relationship between the intensities of secondary electrons and number of layers of h-BN. With the attenuation factor of the exponential formula, we calculate the inelastic mean free path of electrons and helium ions in the h-BN nanosheets. Our results show that HIM is more sensitive and consistent than FE-SEM for characterizing the number of layers and morphology of 2D materials.

Electron beams scanning: A novel method

NASA Astrophysics Data System (ADS)

Askarbioki, M.; Zarandi, M. B.; Khakshournia, S.; Shirmardi, S. P.; Sharifian, M.

2018-06-01

In this research, a spatial electron beam scanning is reported. There are various methods for ion and electron beam scanning. The best known of these methods is the wire scanning wherein the parameters of beam are measured by one or more conductive wires. This article suggests a novel method for e-beam scanning without the previous errors of old wire scanning. In this method, the techniques of atomic physics are applied so that a knife edge has a scanner role and the wires have detector roles. It will determine the 2D e-beam profile readily when the positions of the scanner and detectors are specified.

Scanning Microscopes Using X Rays and Microchannels

NASA Technical Reports Server (NTRS)

Wang, Yu

2003-01-01

Scanning microscopes that would be based on microchannel filters and advanced electronic image sensors and that utilize x-ray illumination have been proposed. Because the finest resolution attainable in a microscope is determined by the wavelength of the illumination, the xray illumination in the proposed microscopes would make it possible, in principle, to achieve resolutions of the order of nanometers about a thousand times as fine as the resolution of a visible-light microscope. Heretofore, it has been necessary to use scanning electron microscopes to obtain such fine resolution. In comparison with scanning electron microscopes, the proposed microscopes would likely be smaller, less massive, and less expensive. Moreover, unlike in scanning electron microscopes, it would not be necessary to place specimens under vacuum. The proposed microscopes are closely related to the ones described in several prior NASA Tech Briefs articles; namely, Miniature Microscope Without Lenses (NPO-20218), NASA Tech Briefs, Vol. 22, No. 8 (August 1998), page 43; and Reflective Variants of Miniature Microscope Without Lenses (NPO-20610), NASA Tech Briefs, Vol. 26, No. 9 (September 2002) page 6a. In all of these microscopes, the basic principle of design and operation is the same: The focusing optics of a conventional visible-light microscope are replaced by a combination of a microchannel filter and a charge-coupled-device (CCD) image detector. A microchannel plate containing parallel, microscopic-cross-section holes much longer than they are wide is placed between a specimen and an image sensor, which is typically the CCD. The microchannel plate must be made of a material that absorbs the illuminating radiation reflected or scattered from the specimen. The microchannels must be positioned and dimensioned so that each one is registered with a pixel on the image sensor. Because most of the radiation incident on the microchannel walls becomes absorbed, the radiation that reaches the image sensor consists predominantly of radiation that was launched along the longitudinal direction of the microchannels. Therefore, most of the radiation arriving at each pixel on the sensor must have traveled along a straight line from a corresponding location on the specimen. Thus, there is a one-to-one mapping from a point on a specimen to a pixel in the image sensor, so that the output of the image sensor contains image information equivalent to that from a microscope.

Reprint of: Atmospheric scanning electron microscope observes cells and tissues in open medium through silicon nitride film.

PubMed

Nishiyama, Hidetoshi; Suga, Mitsuo; Ogura, Toshihiko; Maruyama, Yuusuke; Koizumi, Mitsuru; Mio, Kazuhiro; Kitamura, Shinichi; Sato, Chikara

2010-11-01

Direct observation of subcellular structures and their characterization is essential for understanding their physiological functions. To observe them in open environment, we have developed an inverted scanning electron microscope with a detachable, open-culture dish, capable of 8 nm resolution, and combined with a fluorescence microscope quasi-simultaneously observing the same area from the top. For scanning electron microscopy from the bottom, a silicon nitride film window in the base of the dish maintains a vacuum between electron gun and open sample dish while allowing electrons to pass through. Electrons are backscattered from the sample and captured by a detector under the dish. Cells cultured on the open dish can be externally manipulated under optical microscopy, fixed, and observed using scanning electron microscopy. Once fine structures have been revealed by scanning electron microscopy, their component proteins may be identified by comparison with separately prepared fluorescence-labeled optical microscopic images of the candidate proteins, with their heavy-metal-labeled or stained ASEM images. Furthermore, cell nuclei in a tissue block stained with platinum-blue were successfully observed without thin-sectioning, which suggests the applicability of this inverted scanning electron microscope to cancer diagnosis. This microscope visualizes mesoscopic-scale structures, and is also applicable to non-bioscience fields including polymer chemistry. Copyright © 2010 Elsevier Inc. All rights reserved.

Analyzing indirect secondary electron contrast of unstained bacteriophage T4 based on SEM images and Monte Carlo simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogura, Toshihiko, E-mail: t-ogura@aist.go.jp

2009-03-06

The indirect secondary electron contrast (ISEC) condition of the scanning electron microscopy (SEM) produces high contrast detection with minimal damage of unstained biological samples mounted under a thin carbon film. The high contrast image is created by a secondary electron signal produced under the carbon film by a low acceleration voltage. Here, we show that ISEC condition is clearly able to detect unstained bacteriophage T4 under a thin carbon film (10-15 nm) by using high-resolution field emission (FE) SEM. The results show that FE-SEM provides higher resolution than thermionic emission SEM. Furthermore, we investigated the scattered electron area within themore » carbon film under ISEC conditions using Monte Carlo simulation. The simulations indicated that the image resolution difference is related to the scattering width in the carbon film and the electron beam spot size. Using ISEC conditions on unstained virus samples would produce low electronic damage, because the electron beam does not directly irradiate the sample. In addition to the routine analysis, this method can be utilized for structural analysis of various biological samples like viruses, bacteria, and protein complexes.« less

A new apparatus for electron tomography in the scanning electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morandi, V., E-mail: morandi@bo.imm.cnr.it; Maccagnani, P.; Masini, L.

2015-06-23

The three-dimensional reconstruction of a microscopic specimen has been obtained by applying the tomographic algorithm to a set of images acquired in a Scanning Electron Microscope. This result was achieved starting from a series of projections obtained by stepwise rotating the sample under the beam raster. The Scanning Electron Microscope was operated in the scanning-transmission imaging mode, where the intensity of the transmitted electron beam is a monotonic function of the local mass-density and thickness of the specimen. The detection strategy has been implemented and tailored in order to maintain the projection requirement over the large tilt range, as requiredmore » by the tomographic workflow. A Si-based electron detector and an eucentric-rotation specimen holder have been specifically developed for the purpose.« less

Age and growth of the brick soldierfish, Myripristis amaena

NASA Astrophysics Data System (ADS)

Dee, Anderson J.; Radtke, Richard L.

1989-09-01

Otoliths (sagittae) of the coral reef fish, Myripristis amaena, the brick solderfish were examined internally by Scanning Electron Microscope methods to observe microincrements. The daily nature of increment deposition was validated through tetracycline and acetazolamide marking experiments. Utilization of multivariant mathematical models relating age to otolith size and fish size demonstrated that age could be reliably determined from body measurements and otolith weight measurements. Consequently, M. amaena grows slowly, maturing at about 6 years of age, lives at least 14 years and reaches at least 215 mm SL.

Detection and mapping of trace explosives on surfaces under ambient conditions using multiphoton electron extraction spectroscopy (MEES).

PubMed

Tang, Shisong; Vinerot, Nataly; Fisher, Danny; Bulatov, Valery; Yavetz-Chen, Yehuda; Schechter, Israel

2016-08-01

Multiphoton electron extraction spectroscopy (MEES) is an analytical method in which UV laser pulses are utilized for extracting electrons from solid surfaces in multiphoton processes under ambient conditions. Counting the emitted electrons as a function of laser wavelength results in detailed spectral features, which can be used for material identification. The method has been applied to detection of trace explosives on a variety of surfaces. Detection was possible on dusty swabs spiked with explosives and also in the standard dry-transfer contamination procedure. Plastic explosives could also be detected. The analytical limits of detection (LODs) are in the sub pmole range, which indicates that MEES is one of the most sensitive detection methods for solid surface under ambient conditions. Scanning the surface with the laser allows for its imaging, such that explosives (as well as other materials) can be located. The imaging mode is also useful in forensic applications, such as detection of explosives in human fingerprints. Copyright © 2016 Elsevier B.V. All rights reserved.

Subsurface examination of a foliar biofilm using scanning electron- and focused-ion-beam microscopy

USDA-ARS?s Scientific Manuscript database

The dual beam scanning electron microscope, equipped with both a focused ion- and scanning electron- beam (FIB SEM) is a novel tool for the exploration of the subsurface structure of biological tissues. The FIB is capable of removing small cross sections to view the subsurface features and may be s...

Spatial Resolution in Scanning Electron Microscopy and Scanning Transmission Electron Microscopy Without a Specimen Vacuum Chamber.

PubMed

Nguyen, Kayla X; Holtz, Megan E; Richmond-Decker, Justin; Muller, David A

2016-08-01

A long-standing goal of electron microscopy has been the high-resolution characterization of specimens in their native environment. However, electron optics require high vacuum to maintain an unscattered and focused probe, a challenge for specimens requiring atmospheric or liquid environments. Here, we use an electron-transparent window at the base of a scanning electron microscope's objective lens to separate column vacuum from the specimen, enabling imaging under ambient conditions, without a specimen vacuum chamber. We demonstrate in-air imaging of specimens at nanoscale resolution using backscattered scanning electron microscopy (airSEM) and scanning transmission electron microscopy. We explore resolution and contrast using Monte Carlo simulations and analytical models. We find that nanometer-scale resolution can be obtained at gas path lengths up to 400 μm, although contrast drops with increasing gas path length. As the electron-transparent window scatters considerably more than gas at our operating conditions, we observe that the densities and thicknesses of the electron-transparent window are the dominant limiting factors for image contrast at lower operating voltages. By enabling a variety of detector configurations, the airSEM is applicable to a wide range of environmental experiments including the imaging of hydrated biological specimens and in situ chemical and electrochemical processes.

Spatial Resolution in Scanning Electron Microscopy and Scanning Transmission Electron Microscopy Without a Specimen Vacuum Chamber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Kayla X.; Holtz, Megan E.; Richmond-Decker, Justin

2016-07-25

Abstract A long-standing goal of electron microscopy has been the high-resolution characterization of specimens in their native environment. However, electron optics require high vacuum to maintain an unscattered and focused probe, a challenge for specimens requiring atmospheric or liquid environments. Here, we use an electron-transparent window at the base of a scanning electron microscope’s objective lens to separate column vacuum from the specimen, enabling imaging under ambient conditions, without a specimen vacuum chamber. We demonstrate in-air imaging of specimens at nanoscale resolution using backscattered scanning electron microscopy (airSEM) and scanning transmission electron microscopy. We explore resolution and contrast using Montemore » Carlo simulations and analytical models. We find that nanometer-scale resolution can be obtained at gas path lengths up to 400μm, although contrast drops with increasing gas path length. As the electron-transparent window scatters considerably more than gas at our operating conditions, we observe that the densities and thicknesses of the electron-transparent window are the dominant limiting factors for image contrast at lower operating voltages. By enabling a variety of detector configurations, the airSEM is applicable to a wide range of environmental experiments including the imaging of hydrated biological specimens andin situchemical and electrochemical processes.« less

Shape control VO2 nanorods prepared by soft chemistry and electrochemical method

NASA Astrophysics Data System (ADS)

Simo, A.; Sibanyoni, J.; Fuku, X.; Numan, N.; Omorogbe, S.; Maaza, M.

2018-07-01

"Bottom up" approach is of primary interest for chemistry and materials science because the fundamental building blocks are atoms. Thus colloidal chemical synthetic methods can be utilized to prepare uniform nanocrystals with controlled particle size. In the following work of study, thermochromic VO2 nanostructures were prepared by hydrothermal technique soft chemistry. We concentrate on solution phase synthetic methods that enable a proper shape and size control of metal oxide nanocrystals. Their structural properties were studied by Scanning Electron Microscopy (SEM), Fourier Transform IR (FTIR) and Differential Scanning Calorimetry (DSC). It is demonstrated that the surfactant assistance (NaOH) has great influence on the morphology-control of the material. Electrochemical properties of the nanospheres show good stability after 20 cycles and the surface diffusion coefficient was calculated to be 5 × 10-6 cm2 s-1.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sasaki, David; Rickey, Daniel; Dubey, Arbind

Purpose: We describe the process by which our centre is currently implementing 3D printing and scanning technology for treatment accessory fabrication. This technology can increase efficiency and accuracy of accessory design, production and placement during daily use. Methods: A low-cost 3D printer and 3D optical scanner have been purchased and are being commissioned for clinical use. Commissioning includes assessing: the accuracy of the 3D scanner through comparison with high resolution CT images; the dosimetric characteristics of polylactic acid (PLA) for electron beams; the clinical utility of the technology, and; methods for quality assurance. Results: The agreement between meshes generated usingmore » the 3D scanner and CT data was within 2 millimeters for an anthropomorphic head phantom. In terms of electron beam attenuation, 1 centimetre of printed PLA was found equivalent to 1.17 cm of water. In proof-of-concept tests, several types of treatment accessories have been prototyped to date that will benefit from this technology. These include electron and photon bolus for areas with complex surface contours including the ear for electron treatments, the extremities for photon treatments and lead shielding for orthovoltage treatments. Imaging with CT and x-ray showed minimal defects, which will have no significant clinical impact. Geometric fidelity and fit to volunteers and patients was found to be excellent. Conclusions: 3D Printing and scanning can increase efficiency in the clinic for treatments requiring custom accessories. Customized boluses and shielding had excellent fit and reduced uncertainty in positioning.« less

A scanning electron microscopy study of the macro-crystalline structure of 2-(2,4-dinitrobenzyl) pyridine

NASA Technical Reports Server (NTRS)

Ware, Jacqueline; Hammond, Ernest C., Jr.

1989-01-01

The compound, 2-(2,4-dinitrobenzyl) pyridine, was synthesized in the laboratory; an introductory level electron microscopy study of the macro-crystalline structure was conducted using the scanning electron microscope (SEM). The structure of these crystals was compared with the macrostructure of the crystal of 2-(2,4-dinitrobenzyl) pyridinium bromide, the hydrobromic salt of the compound which was also synthesized in the laboratory. A scanning electron microscopy crystal study was combined with a study of the principle of the electron microscope.

Thermally managed fs Z-scan methods investigation of the size-dependent nonlinearity of Graphene Oxide in different solvents

NASA Astrophysics Data System (ADS)

Burkins, Paul; Basaldua, Isaac; Kuis, Robinson; Johnson, Anthony; Swaminathan, Sivaram; Zhang, Daije; Trivedi, Sudhir; University of Maryland, Baltimore Maryland Team; Brimrose Corporation of America Collaboration

Acoustic and thermal diffusion effects are often ignored in Z-scan measurements resulting in misinterpretation of the nonlinear index of refraction and nonlinear absorption. Thermally managed Z-scan using a modified chopper was compared to utilizing a pulsepicker with the common calibration material CS2 and then extended to Graphene Oxide (GO) in different solvents. The chopper reveals properties of the material in time and is an inexpensive alternative to changing the repetition rate with a pulsepicker. The pulsepicker allows for much faster rise-times and therefore measurements can be taken before thermal effects have overwhelmed the nonlinear electronic response. GO in DI water using pulsepicked fs laser excitation yielded a value of (-1.79 +/-.6)x10-15 cm2/W for nanometer particles and (-1.09 +/-.6)x10-15 cm2/W for micrometer sized particles. Open aperture Z-scan of GO in THF using the modified chopper shows a flip from reverse saturable absorption to saturable absorption in time, previously shown to be intensity dependent, potentially resulting from thermal effects. Both measurements indicate smaller particles have larger negative nonlinearities originating from thermal effects or from defects in lattice structure at the edges.

U-10Mo Sample Preparation and Examination using Optical and Scanning Electron Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prabhakaran, Ramprashad; Joshi, Vineet V.; Rhodes, Mark A.

2016-10-01

The purpose of this document is to provide guidelines to prepare specimens of uranium alloyed with 10 weight percent molybdenum (U-10Mo) for optical metallography and scanning electron microscopy. This document also provides instructions to set up an optical microscope and a scanning electron microscope to analyze U-10Mo specimens and to obtain the required information.

U-10Mo Sample Preparation and Examination using Optical and Scanning Electron Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prabhakaran, Ramprashad; Joshi, Vineet V.; Rhodes, Mark A.

2016-03-30

The purpose of this document is to provide guidelines to prepare specimens of uranium alloyed with 10 weight percent molybdenum (U-10Mo) for optical metallography and scanning electron microscopy. This document also provides instructions to set up an optical microscope and a scanning electron microscope to analyze U-10Mo specimens and to obtain the required information.

Electrical transport in AZO nanorods

NASA Astrophysics Data System (ADS)

Yildiz, A.; Cansizoglu, H.; Karabacak, T.

2015-10-01

Al-doped ZnO (AZO) nanorods (NRs) with different lengths were deposited by utilizing glancing angle deposition (GLAD) technique in a DC sputter system at room temperature. The structural and optical characteristics of the NRs were investigated by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-vis-NIR spectroscopy measurements. A band gap of about 3.5 eV was observed for the NRs. A novel capping process utilizing varying deposition angles was used to introduce a blanket metal top contact for the electrical characterization of NRs. Current-voltage (I-V) measurements were used to properly evaluate the approximate resistivity of a single NR. The electrical conduction was found to be governed by the thermally activated transport mechanism. Activation energy was determined as 0.14 eV from temperature dependent resistivity data.

Direct observation of in-plane anisotropy of the superconducting critical current density in Ba (Fe1-xCox) 2As2 crystals

NASA Astrophysics Data System (ADS)

Hecher, J.; Ishida, S.; Song, D.; Ogino, H.; Iyo, A.; Eisaki, H.; Nakajima, M.; Kagerbauer, D.; Eisterer, M.

2018-01-01

The phase diagram of iron-based superconductors exhibits structural transitions, electronic nematicity, and magnetic ordering, which are often accompanied by an electronic in-plane anisotropy and a sharp maximum of the superconducting critical current density (Jc) near the phase boundary of the tetragonal and the antiferromagnetic-orthorhombic phase. We utilized scanning Hall-probe microscopy to visualize the Jc of twinned and detwinned Ba (Fe1-xCox) 2As2 (x =5 %-8 % ) crystals to compare the electronic normal state properties with superconducting properties. We find that the electronic in-plane anisotropy continues into the superconducting state. The observed correlation between the electronic and the Jc anisotropy agrees qualitatively with basic models, however, the Jc anisotropy is larger than predicted from the resistivity data. Furthermore, our measurements show that the maximum of Jc at the phase boundary does not vanish when the crystals are detwinned. This shows that twin boundaries are not responsible for the large Jc, suggesting an exotic pinning mechanism.

Synthesis of 3D iron and carbon-based composite as a bifunctional sorbent and catalyst for remediation of organic pollutants

NASA Astrophysics Data System (ADS)

Li, Ling; Shen, Yi; Wang, Zhaomei

2017-07-01

We prepared a 3D monolith by integrating graphite nanosheet encapsulated iron nanoparticles (Fe@GNS) into graphite felt (GF) supports. The structural properties of the resulting Fe@GNS/GF monolith are characterized by x-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy and N2 adsorption-desorption isotherms. The Fe@GNS/GF monoliths are utilized as a bifunctional sorbent and catalyst for water remediation. Using Congo red and methyl violet 2B as model pollutants, the sorption and catalytic performance of the Fe@GNS/GF composite are examined. The Fe@GNS/GF monolith possesses maximum sorption capacities of 177 and 142 mg g-1 for the sorption of CR and MV-2B, respectively. It also exhibits rate constants of 0.0563 and 0.0464 min-1 for the catalytic degradation of CR and MV-2B, respectively. As a proof of concept, the Fe@GNS/GF is successfully utilized to decontaminate simulated organic waste water via a combination of sorption and catalytic degradation processes.

Improving Secondary Ion Mass Spectrometry Image Quality with Image Fusion

NASA Astrophysics Data System (ADS)

Tarolli, Jay G.; Jackson, Lauren M.; Winograd, Nicholas

2014-12-01

The spatial resolution of chemical images acquired with cluster secondary ion mass spectrometry (SIMS) is limited not only by the size of the probe utilized to create the images but also by detection sensitivity. As the probe size is reduced to below 1 μm, for example, a low signal in each pixel limits lateral resolution because of counting statistics considerations. Although it can be useful to implement numerical methods to mitigate this problem, here we investigate the use of image fusion to combine information from scanning electron microscope (SEM) data with chemically resolved SIMS images. The advantage of this approach is that the higher intensity and, hence, spatial resolution of the electron images can help to improve the quality of the SIMS images without sacrificing chemical specificity. Using a pan-sharpening algorithm, the method is illustrated using synthetic data, experimental data acquired from a metallic grid sample, and experimental data acquired from a lawn of algae cells. The results show that up to an order of magnitude increase in spatial resolution is possible to achieve. A cross-correlation metric is utilized for evaluating the reliability of the procedure.

Correcting nonlinear drift distortion of scanning probe and scanning transmission electron microscopies from image pairs with orthogonal scan directions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ophus, Colin; Ciston, Jim; Nelson, Chris T.

Unwanted motion of the probe with respect to the sample is a ubiquitous problem in scanning probe and scanning transmission electron microscopies, causing both linear and nonlinear artifacts in experimental images. We have designed a procedure to correct these artifacts by using orthogonal scan pairs to align each measurement line-by-line along the slow scan direction, by fitting contrast variation along the lines. We demonstrate the accuracy of our algorithm on both synthetic and experimental data and provide an implementation of our method.

Correcting nonlinear drift distortion of scanning probe and scanning transmission electron microscopies from image pairs with orthogonal scan directions

DOE PAGES

Ophus, Colin; Ciston, Jim; Nelson, Chris T.

2015-12-10

Unwanted motion of the probe with respect to the sample is a ubiquitous problem in scanning probe and scanning transmission electron microscopies, causing both linear and nonlinear artifacts in experimental images. We have designed a procedure to correct these artifacts by using orthogonal scan pairs to align each measurement line-by-line along the slow scan direction, by fitting contrast variation along the lines. We demonstrate the accuracy of our algorithm on both synthetic and experimental data and provide an implementation of our method.

Surface characterization of Nb samples electropolished together with real superconducting rf accelerator cavities

DOE PAGES

Xin Zhao; Geng, Rong -Li; Tyagi, P. V.; ...

2010-12-30

Here, we report the results of surface characterizations of niobium (Nb) samples electropolished together with a single cell superconducting radio-frequency accelerator cavity. These witness samples were located in three regions of the cavity, namely at the equator, the iris and the beam-pipe. Auger electron spectroscopy (AES) was utilized to probe the chemical composition of the topmost four atomic layers. Scanning electron microscopy with energy dispersive X-ray for elemental analysis (SEM/EDX) was used to observe the surface topography and chemical composition at the micrometer scale. A few atomic layers of sulfur (S) were found covering the samples non-uniformly. Niobium oxide granulesmore » with a sharp geometry were observed on every sample. Some Nb-O granules appeared to also contain sulfur.« less

Tip-induced local strain on Mo S 2 / graphite detected by inelastic electron tunneling spectroscopy

DOE PAGES

Ko, Wonhee; Hus, Saban M.; Li, Xufan; ...

2018-03-02

We report the detection of tip-induced local strain applied to the monolayer MoS 2 grown on a graphite substrate by scanning tunneling microscope. Monolayer MoS 2 behaves as both mechanical and tunneling barriers that prevent the tip from contacting the graphite while maintaining the tunneling current. Inelastic tunneling electron spectroscopy (IETS) is utilized to probe the phonon modes in graphite. As the tip pushes the sample, IETS reveals a continuous phonon softening in graphite, corroborated by a downward shift of the phonon energy as calculated by density-functional theory. Finally, our results demonstrate a way to apply local mechanical strain andmore » simultaneously detect the induced change in phonon modes by unitizing IETS with two-dimensional materials as a tunneling barrier.« less

Tip-induced local strain on Mo S 2 / graphite detected by inelastic electron tunneling spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ko, Wonhee; Hus, Saban M.; Li, Xufan

We report the detection of tip-induced local strain applied to the monolayer MoS 2 grown on a graphite substrate by scanning tunneling microscope. Monolayer MoS 2 behaves as both mechanical and tunneling barriers that prevent the tip from contacting the graphite while maintaining the tunneling current. Inelastic tunneling electron spectroscopy (IETS) is utilized to probe the phonon modes in graphite. As the tip pushes the sample, IETS reveals a continuous phonon softening in graphite, corroborated by a downward shift of the phonon energy as calculated by density-functional theory. Finally, our results demonstrate a way to apply local mechanical strain andmore » simultaneously detect the induced change in phonon modes by unitizing IETS with two-dimensional materials as a tunneling barrier.« less

Electrodeposition of actinide compounds from an aqueous ammonium acetate matrix. Experimental development and optimization

DOE PAGES

Boll, Rose Ann; Matos, Milan; Torrico, Matthew N.

2015-03-27

Electrodeposition is a technique that is routinely employed in nuclear research for the preparation of thin solid films of actinide materials which can be used in accelerator beam bombardments, irradiation studies, or as radioactive sources. The present study investigates the deposition of both lanthanides and actinides from an aqueous ammonium acetate electrolyte matrix. Electrodepositions were performed primarily on stainless steel disks; with yield analysis evaluated using -spectroscopy. Experimental parameters were studied and modified in order to optimize the uniformity and adherence of the deposition while maximizing the yield. The initial development utilized samarium as the plating material, with and withoutmore » a radioactive tracer. As a result, surface characterization studies were performed by scanning electron microscopy, electron microprobe analysis, radiographic imaging, and x-ray diffraction.« less

Tip-induced local strain on Mo S2/graphite detected by inelastic electron tunneling spectroscopy

NASA Astrophysics Data System (ADS)

Ko, Wonhee; Hus, Saban M.; Li, Xufan; Berlijn, Tom; Nguyen, Giang D.; Xiao, Kai; Li, An-Ping

2018-03-01

We report the detection of tip-induced local strain applied to the monolayer Mo S2 grown on a graphite substrate by scanning tunneling microscope. Monolayer Mo S2 behaves as both mechanical and tunneling barriers that prevent the tip from contacting the graphite while maintaining the tunneling current. Inelastic tunneling electron spectroscopy (IETS) is utilized to probe the phonon modes in graphite. As the tip pushes the sample, IETS reveals a continuous phonon softening in graphite, corroborated by a downward shift of the phonon energy as calculated by density-functional theory. Our results demonstrate a way to apply local mechanical strain and simultaneously detect the induced change in phonon modes by unitizing IETS with two-dimensional materials as a tunneling barrier.

Preparation of poly(2-amino thiophenol) nanodiscs by a "combined hard-soft template" approach and characterization.

PubMed

Komathi, Shanmugasundaram; Palaniappan, Subramanian; Manisankar, Paramasivam; Gopalan, Anantha Iyengar; Lee, Kwang-Pill

2010-12-15

A seed induced chemical oxidative polymerization was used for the preparation of pure poly(2-amino thiophenol) nanodiscs (P2AT-NDs (P)). Two templates, (hard (MCM-41) and soft (β-napthalene sulfonic acid), were utilized for the preparation of the seed, P2AT nanostructures loaded MCM-41. The field emission scanning electron microscopy reveals nanodisc morphology for P2AT (P). X-ray diffraction, current-potential characteristics and electrochemical impedance spectroscopy were used to evaluate the physicochemical properties of P2AT-ND (P). The P2AT-ND (P) exhibits semicrystalline behaviour, good electron transport and lesser charge transfer resistance at the interface as compared to simple P2AT prepared by conventional chemical route. Copyright © 2010 Elsevier Inc. All rights reserved.

High-resolution, high-throughput imaging with a multibeam scanning electron microscope

PubMed Central

EBERLE, AL; MIKULA, S; SCHALEK, R; LICHTMAN, J; TATE, ML KNOTHE; ZEIDLER, D

2015-01-01

Electron–electron interactions and detector bandwidth limit the maximal imaging speed of single-beam scanning electron microscopes. We use multiple electron beams in a single column and detect secondary electrons in parallel to increase the imaging speed by close to two orders of magnitude and demonstrate imaging for a variety of samples ranging from biological brain tissue to semiconductor wafers. Lay Description The composition of our world and our bodies on the very small scale has always fascinated people, making them search for ways to make this visible to the human eye. Where light microscopes reach their resolution limit at a certain magnification, electron microscopes can go beyond. But their capability of visualizing extremely small features comes at the cost of a very small field of view. Some of the questions researchers seek to answer today deal with the ultrafine structure of brains, bones or computer chips. Capturing these objects with electron microscopes takes a lot of time – maybe even exceeding the time span of a human being – or new tools that do the job much faster. A new type of scanning electron microscope scans with 61 electron beams in parallel, acquiring 61 adjacent images of the sample at the same time a conventional scanning electron microscope captures one of these images. In principle, the multibeam scanning electron microscope’s field of view is 61 times larger and therefore coverage of the sample surface can be accomplished in less time. This enables researchers to think about large-scale projects, for example in the rather new field of connectomics. A very good introduction to imaging a brain at nanometre resolution can be found within course material from Harvard University on http://www.mcb80x.org/# as featured media entitled ‘connectomics’. PMID:25627873

Novel high power impulse magnetron sputtering enhanced by an auxiliary electrical field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Chunwei, E-mail: lcwnefu@126.com, E-mail: xiubotian@163.com; State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001; Tian, Xiubo, E-mail: lcwnefu@126.com, E-mail: xiubotian@163.com

2016-08-15

The high power impulse magnetron sputtering (HIPIMS) technique is a novel highly ionized physical vapor deposition method with a high application potential. However, the electron utilization efficiency during sputtering is rather low and the metal particle ionization rate needs to be considerably improved to allow for a large-scale industrial application. Therefore, we enhanced the HIPIMS technique by simultaneously applying an electric field (EF-HIPIMS). The effect of the electric field on the discharge process was studied using a current sensor and an optical emission spectrometer. Furthermore, the spatial distribution of the electric potential and electric field during the EF-HIPIMS process wasmore » simulated using the ANSYS software. The results indicate that a higher electron utilization efficiency and a higher particle ionization rate could be achieved. The auxiliary anode obviously changed the distribution of the electric potential and the electric field in the discharge region, which increased the plasma density and enhanced the degree of ionization of the vanadium and argon gas. Vanadium films were deposited to further compare both techniques, and the morphology of the prepared films was investigated by scanning electron microscopy. The films showed a smaller crystal grain size and a denser growth structure when the electric field was applied during the discharge process.« less

Electronic Photography at the NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Holm, Jack; Judge, Nancianne

1995-01-01

An electronic photography facility has been established in the Imaging & Photographic Technology Section, Visual Imaging Branch, at the NASA Langley Research Center (LaRC). The purpose of this facility is to provide the LaRC community with access to digital imaging technology. In particular, capabilities have been established for image scanning, direct image capture, optimized image processing for storage, image enhancement, and optimized device dependent image processing for output. Unique approaches include: evaluation and extraction of the entire film information content through scanning; standardization of image file tone reproduction characteristics for optimal bit utilization and viewing; education of digital imaging personnel on the effects of sampling and quantization to minimize image processing related information loss; investigation of the use of small kernel optimal filters for image restoration; characterization of a large array of output devices and development of image processing protocols for standardized output. Currently, the laboratory has a large collection of digital image files which contain essentially all the information present on the original films. These files are stored at 8-bits per color, but the initial image processing was done at higher bit depths and/or resolutions so that the full 8-bits are used in the stored files. The tone reproduction of these files has also been optimized so the available levels are distributed according to visual perceptibility. Look up tables are available which modify these files for standardized output on various devices, although color reproduction has been allowed to float to some extent to allow for full utilization of output device gamut.

A highly sensitive electron spectrometer for crossed-beam collisional ionization: A retarding-type magnetic bottle analyzer and its application to collision-energy resolved Penning ionization electron spectroscopy

NASA Astrophysics Data System (ADS)

Yamakita, Yoshihiro; Tanaka, Hideyasu; Maruyama, Ryo; Yamakado, Hideo; Misaizu, Fuminori; Ohno, Koichi

2000-08-01

A highly sensitive electron energy analyzer which utilizes a "magnetic bottle" combined with a retarding electrostatic field has been developed for Penning ionization electron spectroscopy. A beam of metastable rare-gas atoms is crossed with a continuous supersonic sample beam in the source region of the analyzer. The emitted electrons are collected by an inhomogeneous magnetic field (the magnetic bottle effect) with a high efficiency of nearly 4π solid angle, which is more than 103 times higher than that of a conventional hemispherical analyzer. The kinetic energy of electrons is analyzed by scanning the retarding field in a flight tube of the analyzer in the presence of a weak magnetic field. The velocity of the metastable atoms can also be resolved by a time-of-flight method in the present instrument. Examples of Penning ionization electron energy spectra as a function of collision energy are presented for Ar and N2 with metastable He*(2 3S) atoms. This instrument has opened the possibility for extensive studies of Penning ionization electron spectroscopy for low-density species, such as clusters, ions, electronically excited species, unstable or transient species, and large molecules with low volatility.

Anomalous transport in the H-mode pedestal of Alcator C-Mod discharges

NASA Astrophysics Data System (ADS)

Pankin, A. Y.; Hughes, J. W.; Greenwald, M. J.; Kritz, A. H.; Rafiq, T.

2017-02-01

Anomalous transport in the H-mode pedestal region of five Alcator C-Mod discharges, representing a collisionality scan is analyzed. The understanding of anomalous transport in the pedestal region is important for the development of a comprehensive model for the H-mode pedestal slope. In this research, a possible role of the drift resistive inertial ballooning modes (Rafiq et al 2010 Phys. Plasmas 17 082511) in the edge of Alcator C-Mod discharges is analyzed. The stability analysis, carried out using the TRANSP code, indicates that the DRIBM modes are strongly unstable in Alcator C-Mod discharges with large electron collisionality. An improved interpretive analysis of H-mode pedestal experimental data is carried out utilizing the additive flux minimization technique (Pankin et al 2013 Phys. Plasmas 20 102501) together with the guiding-center neoclassical kinetic XGC0 code. The neoclassical and neutral physics are simulated in the XGC0 code and the anomalous fluxes are computed using the additive flux minimization technique. The anomalous fluxes are reconstructed and compared with each other for the collisionality scan Alcator C-Mod discharges. It is found that the electron thermal anomalous diffusivities at the pedestal top increase with the electron collisionality. This dependence can also point to the drift resistive inertial ballooning modes as the modes that drive the anomalous transport in the plasma edge of highly collisional discharges.

High-resolution scanning precession electron diffraction: Alignment and spatial resolution.

PubMed

Barnard, Jonathan S; Johnstone, Duncan N; Midgley, Paul A

2017-03-01

Methods are presented for aligning the pivot point of a precessing electron probe in the scanning transmission electron microscope (STEM) and for assessing the spatial resolution in scanning precession electron diffraction (SPED) experiments. The alignment procedure is performed entirely in diffraction mode, minimising probe wander within the bright-field (BF) convergent beam electron diffraction (CBED) disk and is used to obtain high spatial resolution SPED maps. Through analysis of the power spectra of virtual bright-field images extracted from the SPED data, the precession-induced blur was measured as a function of precession angle. At low precession angles, SPED spatial resolution was limited by electronic noise in the scan coils; whereas at high precession angles SPED spatial resolution was limited by tilt-induced two-fold astigmatism caused by the positive spherical aberration of the probe-forming lens. Copyright © 2016 Elsevier B.V. All rights reserved.

The application of scanning electron microscopy to fractography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brooks, C.R.; McGill, B.L.

1994-10-01

Many failures involve fracture, and determination of the fracture process is a key factor in understanding the failure. This is frequently accomplished by characterizing the topography of the fracture surface. Scanning electron microscopy has a prominent role in fractography due to three features of the scanning electron microscope (SEM): high resolution, great depth of field, and the ability to obtain chemical information via analysis of the X-rays generated by the electrons. A qualitative treatment is presented of the interaction of electrons with a sample and the effect of the SEM operating parameters on image formation, quality, and X-ray analysis. Fractographsmore » are presented to illustrate these features of scanning electron microscopy and to illustrate the limitations and precautions in obtaining fractographs and x-ray analyses. The review is concluded with examples of fracture surface features of metallic, ceramic, and polymeric materials.« less

On the Progress of Scanning Transmission Electron Microscopy (STEM) Imaging in a Scanning Electron Microscope.

PubMed

Sun, Cheng; Müller, Erich; Meffert, Matthias; Gerthsen, Dagmar

2018-04-01

Transmission electron microscopy (TEM) with low-energy electrons has been recognized as an important addition to the family of electron microscopies as it may avoid knock-on damage and increase the contrast of weakly scattering objects. Scanning electron microscopes (SEMs) are well suited for low-energy electron microscopy with maximum electron energies of 30 keV, but they are mainly used for topography imaging of bulk samples. Implementation of a scanning transmission electron microscopy (STEM) detector and a charge-coupled-device camera for the acquisition of on-axis transmission electron diffraction (TED) patterns, in combination with recent resolution improvements, make SEMs highly interesting for structure analysis of some electron-transparent specimens which are traditionally investigated by TEM. A new aspect is correlative SEM, STEM, and TED imaging from the same specimen region in a SEM which leads to a wealth of information. Simultaneous image acquisition gives information on surface topography, inner structure including crystal defects and qualitative material contrast. Lattice-fringe resolution is obtained in bright-field STEM imaging. The benefits of correlative SEM/STEM/TED imaging in a SEM are exemplified by structure analyses from representative sample classes such as nanoparticulates and bulk materials.

Imaging of Norway spruce early somatic embryos with the ESEM, Cryo-SEM and laser scanning microscope.

PubMed

Neděla, Vilém; Hřib, Jiří; Havel, Ladislav; Hudec, Jiří; Runštuk, Jiří

2016-05-01

This article describes the surface structure of Norway spruce early somatic embryos (ESEs) as a typical culture with asynchronous development. The microstructure of extracellular matrix covering ESEs were observed using the environmental scanning electron microscope as a primary tool and using the scanning electron microscope with cryo attachment and laser electron microscope as a complementary tool allowing our results to be proven independently. The fresh samples were observed in conditions of the air environment of the environmental scanning electron microscope (ESEM) with the pressure from 550Pa to 690Pa and the low temperature of the sample from -18°C to -22°C. The samples were studied using two different types of detector to allow studying either the thin surface structure or material composition. The scanning electron microscope with cryo attachment was used for imaging frozen extracellular matrix microstructure with higher resolution. The combination of both electron microscopy methods was suitable for observation of "native" plant samples, allowing correct evaluation of our results, free of error and artifacts. Copyright © 2016 Elsevier Ltd. All rights reserved.

A correlative optical microscopy and scanning electron microscopy approach to locating nanoparticles in brain tumors.

PubMed

Kempen, Paul J; Kircher, Moritz F; de la Zerda, Adam; Zavaleta, Cristina L; Jokerst, Jesse V; Mellinghoff, Ingo K; Gambhir, Sanjiv S; Sinclair, Robert

2015-01-01

The growing use of nanoparticles in biomedical applications, including cancer diagnosis and treatment, demands the capability to exactly locate them within complex biological systems. In this work a correlative optical and scanning electron microscopy technique was developed to locate and observe multi-modal gold core nanoparticle accumulation in brain tumor models. Entire brain sections from mice containing orthotopic brain tumors injected intravenously with nanoparticles were imaged using both optical microscopy to identify the brain tumor, and scanning electron microscopy to identify the individual nanoparticles. Gold-based nanoparticles were readily identified in the scanning electron microscope using backscattered electron imaging as bright spots against a darker background. This information was then correlated to determine the exact location of the nanoparticles within the brain tissue. The nanoparticles were located only in areas that contained tumor cells, and not in the surrounding healthy brain tissue. This correlative technique provides a powerful method to relate the macro- and micro-scale features visible in light microscopy with the nanoscale features resolvable in scanning electron microscopy. Copyright © 2014 Elsevier Ltd. All rights reserved.

Crystal Structure, Magnetic and Optical Properties of Mn-Doped BiFeO₃ by Hydrothermal Synthesis.

PubMed

Zhang, Ning; Wei, Qinhua; Qin, Laishun; Chen, Da; Chen, Zhi; Niu, Feng; Wang, Jiangying; Huanag, Yuexiang

2017-01-01

In this paper, Mn doped BiFeO₃ were firstly synthesized by hydrothermal process. The influence of Mn doping on structural, optical and magnetic properties of BiFeO₃ was studied. The different amounts of Mn doping in BiFeO₃ were characterized by X-ray diffraction, Scanning Electron Microscope, Energy Dispersive X-ray Spectroscope, UV-Vis diffuse reflectance spectroscopy and magnetic measurements. The X-ray diffraction (XRD) patterns confirmed the formation of pure phase rhombohedral structure in BiFe(1−x) Mn (x) O₃ (x = 0.01, 0.03, 0.05, 0.07) samples. The morphologies and chemical compositions of as-prepared samples could be observed by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscope (EDS). A relative large saturated magnetization (Ms) of 0.53 emu/g for x = 0.07 sample was obtained at room temperature, which is considered to be Mn ions doping. UV-Vis diffuse reflectance spectroscopy showed strong absorption of light in the range of 200–1000 nm, indicating the optical band gap in the visible region for these samples. This implied that BiFe(1−x) Mn(x)O₃ may be a potential photocatalyst for utilizing solar energy.

New developments in electron microscopy for serial image acquisition of neuronal profiles.

PubMed

Kubota, Yoshiyuki

2015-02-01

Recent developments in electron microscopy largely automate the continuous acquisition of serial electron micrographs (EMGs), previously achieved by laborious manual serial ultrathin sectioning using an ultramicrotome and ultrastructural image capture process with transmission electron microscopy. The new systems cut thin sections and capture serial EMGs automatically, allowing for acquisition of large data sets in a reasonably short time. The new methods are focused ion beam/scanning electron microscopy, ultramicrotome/serial block-face scanning electron microscopy, automated tape-collection ultramicrotome/scanning electron microscopy and transmission electron microscope camera array. In this review, their positive and negative aspects are discussed. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Feasibility of utilizing a commercial eye tracker to assess electronic health record use during patient simulation.

PubMed

Gold, Jeffrey Allen; Stephenson, Laurel E; Gorsuch, Adriel; Parthasarathy, Keshav; Mohan, Vishnu

2016-09-01

Numerous reports describe unintended consequences of electronic health record implementation. Having previously described physicians' failures to recognize patient safety issues within our electronic health record simulation environment, we now report on our use of eye and screen-tracking technology to understand factors associated with poor error recognition during an intensive care unit-based electronic health record simulation. We linked performance on the simulation to standard eye and screen-tracking readouts including number of fixations, saccades, mouse clicks and screens visited. In addition, we developed an overall Composite Eye Tracking score which measured when, where and how often each safety item was viewed. For 39 participants, the Composite Eye Tracking score correlated with performance on the simulation (p = 0.004). Overall, the improved performance was associated with a pattern of rapid scanning of data manifested by increased number of screens visited (p = 0.001), mouse clicks (p = 0.03) and saccades (p = 0.004). Eye tracking can be successfully integrated into electronic health record-based simulation and provides a surrogate measure of cognitive decision making and electronic health record usability. © The Author(s) 2015.

Development of a Multi-Band Shared Aperture Reflectarray/Reflector Antenna Design for NASA

NASA Technical Reports Server (NTRS)

Spence, Thomas; Cooley, Michael; Stenger, Peter; Park, Richard; Li, Lihua; Racette, Paul; Heymsfield, Gerald; Mclinden, Matthew

2016-01-01

A dual-band (Ka/W) shared-aperture antenna system design has been developed as a proposed solution to meet the needs of NASA's planned Aerosol, Clouds, and Ecosystem (ACE) mission. The design is comprised of a compact Cassegrain reflector/reflect array with a fixed W-band feed and a cross track scanned Ka-band Active Electronically Scanned Array (AESA). Critical Sub-scale prototype testing and flight tests have validated some of the key aspects of this innovative antenna design, including the low loss reflector/reflect array surface. More recently the science community has expressed interest in a mission that offers the ability to measure precipitation (Ku- band with scanning) in addition to clouds and aerosols. In this paper we present findings from a design study that explores options for realizing a tri-frequency (Ku/Ka/W), shared-aperture antenna system to meet these science objectives. Design considerations included meeting performance requirements while striving to minimize payload size, weight, prime power, and cost. The extensive trades and lessons learned from the ACE system development were utilized as the foundation for this work.

Precision controlled atomic resolution scanning transmission electron microscopy using spiral scan pathways

NASA Astrophysics Data System (ADS)

Sang, Xiahan; Lupini, Andrew R.; Ding, Jilai; Kalinin, Sergei V.; Jesse, Stephen; Unocic, Raymond R.

2017-03-01

Atomic-resolution imaging in an aberration-corrected scanning transmission electron microscope (STEM) can enable direct correlation between atomic structure and materials functionality. The fast and precise control of the STEM probe is, however, challenging because the true beam location deviates from the assigned location depending on the properties of the deflectors. To reduce these deviations, i.e. image distortions, we use spiral scanning paths, allowing precise control of a sub-Å sized electron probe within an aberration-corrected STEM. Although spiral scanning avoids the sudden changes in the beam location (fly-back distortion) present in conventional raster scans, it is not distortion-free. “Archimedean” spirals, with a constant angular frequency within each scan, are used to determine the characteristic response at different frequencies. We then show that such characteristic functions can be used to correct image distortions present in more complicated constant linear velocity spirals, where the frequency varies within each scan. Through the combined application of constant linear velocity scanning and beam path corrections, spiral scan images are shown to exhibit less scan distortion than conventional raster scan images. The methodology presented here will be useful for in situ STEM imaging at higher temporal resolution and for imaging beam sensitive materials.

Precision controlled atomic resolution scanning transmission electron microscopy using spiral scan pathways.

PubMed

Sang, Xiahan; Lupini, Andrew R; Ding, Jilai; Kalinin, Sergei V; Jesse, Stephen; Unocic, Raymond R

2017-03-08

Atomic-resolution imaging in an aberration-corrected scanning transmission electron microscope (STEM) can enable direct correlation between atomic structure and materials functionality. The fast and precise control of the STEM probe is, however, challenging because the true beam location deviates from the assigned location depending on the properties of the deflectors. To reduce these deviations, i.e. image distortions, we use spiral scanning paths, allowing precise control of a sub-Å sized electron probe within an aberration-corrected STEM. Although spiral scanning avoids the sudden changes in the beam location (fly-back distortion) present in conventional raster scans, it is not distortion-free. "Archimedean" spirals, with a constant angular frequency within each scan, are used to determine the characteristic response at different frequencies. We then show that such characteristic functions can be used to correct image distortions present in more complicated constant linear velocity spirals, where the frequency varies within each scan. Through the combined application of constant linear velocity scanning and beam path corrections, spiral scan images are shown to exhibit less scan distortion than conventional raster scan images. The methodology presented here will be useful for in situ STEM imaging at higher temporal resolution and for imaging beam sensitive materials.

Point Relay Scanner Utilizing Ellipsoidal Mirrors

NASA Technical Reports Server (NTRS)

Manhart, Paul K. (Inventor); Pagano, Robert J. (Inventor)

1997-01-01

A scanning system uses a polygonal mirror assembly with each facet of the polygon having an ellipsoidal mirror located thereon. One focal point of each ellipsoidal mirror is located at a common point on the axis of rotation of the polygonal mirror assembly. As the mirror assembly rotates. a second focal point of the ellipsoidal mirrors traces out a scan line. The scanner can be utilized for scanned output display of information or for scanning information to be detected.

Knowledge Extraction from Atomically Resolved Images.

PubMed

Vlcek, Lukas; Maksov, Artem; Pan, Minghu; Vasudevan, Rama K; Kalinin, Sergei V

2017-10-24

Tremendous strides in experimental capabilities of scanning transmission electron microscopy and scanning tunneling microscopy (STM) over the past 30 years made atomically resolved imaging routine. However, consistent integration and use of atomically resolved data with generative models is unavailable, so information on local thermodynamics and other microscopic driving forces encoded in the observed atomic configurations remains hidden. Here, we present a framework based on statistical distance minimization to consistently utilize the information available from atomic configurations obtained from an atomically resolved image and extract meaningful physical interaction parameters. We illustrate the applicability of the framework on an STM image of a FeSe x Te 1-x superconductor, with the segregation of the chalcogen atoms investigated using a nonideal interacting solid solution model. This universal method makes full use of the microscopic degrees of freedom sampled in an atomically resolved image and can be extended via Bayesian inference toward unbiased model selection with uncertainty quantification.

Physicochemical and mechanical properties of paracetamol cocrystal with 5-nitroisophthalic acid.

PubMed

Hiendrawan, Stevanus; Veriansyah, Bambang; Widjojokusumo, Edward; Soewandhi, Sundani Nurono; Wikarsa, Saleh; Tjandrawinata, Raymond R

2016-01-30

We report novel pharmaceutical cocrystal of a popular antipyretic drug paracetamol (PCA) with coformer 5-nitroisophhthalic acid (5NIP) to improve its tabletability. The cocrystal (PCA-5NIP at molar ratio of 1:1) was synthesized by solvent evaporation technique using methanol as solvent. The physicochemical properties of cocrystal were characterized by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), fourier transform infrared spectroscopy (FTIR), hot stage polarized microscopy (HSPM) and scanning electron microscopy (SEM). Stability of the cocrystal was assessed by storing them at 40°C/75% RH for one month. Compared to PCA, the cocrystal displayed superior tableting performance. PCA-5NIP cocrystal showed a similar dissolution profile as compared to PCA and exhibited good stability. This study showed the utility of PCA-5NIP cocrystal for improving mechanical properties of PCA. Copyright © 2015 Elsevier B.V. All rights reserved.

Multiple microscopic approaches demonstrate linkage between chromoplast architecture and carotenoid composition in diverse Capsicum annuum fruit.

PubMed

Kilcrease, James; Collins, Aaron M; Richins, Richard D; Timlin, Jerilyn A; O'Connell, Mary A

2013-12-01

Increased accumulation of specific carotenoids in plastids through plant breeding or genetic engineering requires an understanding of the limitations that storage sites for these compounds may impose on that accumulation. Here, using Capsicum annuum L. fruit, we demonstrate directly the unique sub-organellar accumulation sites of specific carotenoids using live cell hyperspectral confocal Raman microscopy. Further, we show that chromoplasts from specific cultivars vary in shape and size, and these structural variations are associated with carotenoid compositional differences. Live-cell imaging utilizing laser scanning confocal (LSCM) and confocal Raman microscopy, as well as fixed tissue imaging by scanning and transmission electron microscopy (SEM and TEM), all demonstrated morphological differences with high concordance for the measurements across the multiple imaging modalities. These results reveal additional opportunities for genetic controls on fruit color and carotenoid-based phenotypes. © 2013 The Authors The Plant Journal © 2013 John Wiley & Sons Ltd.

Thermal Storage Properties of Molten Nitrate Salt-Based Nanofluids with Graphene Nanoplatelets.

PubMed

Xie, Qiangzhi; Zhu, Qunzhi; Li, Yan

2016-12-01

In this study, the effect of concentration of nanoparticles on the thermal storage properties of molten nitrate salt-based nanofluids with graphene nanoplatelets (GNPs) was investigated. Solar salt consisting of sodium nitrate and potassium nitrate was utilized as the base material for the nanofluids. Homogeneous dispersion of GNPs within the solar salt was observed through scanning electron microscopy analysis. For both solar salt and resultant nanofluids, differential scanning calorimetry was employed to measure the thermal storage properties, including characteristic temperatures of phase change, startup heat, and specific heat capacity (SHC). A maximum increase of 16.7 % in SHC at the liquid phase was found at an optimal concentration of 1 wt% of GNPs. At the same concentration, the onset temperature decreased by 10.4 °C, the endset temperature decreased by 4.7 °C, and the startup heat decreased by 9 %.

[Effects of Gravity on Attachment of Tendon to Bone

NASA Technical Reports Server (NTRS)

Johnson, Roger B.

1997-01-01

We have received and processed all samples for either light or scanning electron microscopic analysis and have completed the histomorphometric analysis. We have characterized the changes caused by spaceflight to tendon attachments to the calcaneus, tibia, fibula and femur and compared them to hindlimbs and forelimbs from NIH.RZ. Soleus muscle histomorphometry has also been completed. Our results suggest severe osteoporosis in the femur, fibula and tibia of animals coincident to spaceflight, which had not resolved after 4-5 days following return to earth. This was evident at all sites, including sites of tendon attachments. This atrophy was not evident in the calcaneus. No muscle atrophy was evident. Comparison of scanning photomicrographs of flight animals with other lactating animals demonstrated structural similarities and suggested that it might be worthwhile to assess whether lactation is a factor in development of the osteoporosis in the spaceflight animals. In addition, evaluation of total calcium utilization by spaceflight animals would be beneficial.

The Scanning Electron Microscope and the Archaeologist

ERIC Educational Resources Information Center

Ponting, Matthew

2004-01-01

Images from scanning electron microscopy are now quite common and they can be of great value in archaeology. Techniques such as secondary electron imaging, backscattered electron imaging and energy-dispersive x-ray analysis can reveal information such as the presence of weevils in grain in Roman Britain, the composition of Roman coins and the…

Area-selective atomic layer deposition of Ru on electron-beam-written Pt(C) patterns versus SiO2 substratum

NASA Astrophysics Data System (ADS)

Junige, Marcel; Löffler, Markus; Geidel, Marion; Albert, Matthias; Bartha, Johann W.; Zschech, Ehrenfried; Rellinghaus, Bernd; van Dorp, Willem F.

2017-09-01

Area selectivity is an emerging sub-topic in the field of atomic layer deposition (ALD), which employs opposite nucleation phenomena to distinct heterogeneous starting materials on a surface. In this paper, we intend to grow Ru exclusively on locally pre-defined Pt patterns, while keeping a SiO2 substratum free from any deposition. In a first step, we study in detail the Ru ALD nucleation on SiO2 and clarify the impact of the set-point temperature. An initial incubation period with actually no growth was revealed before a formation of minor, isolated RuO x islands; clearly no continuous Ru layer formed on SiO2. A lower temperature was beneficial in facilitating a longer incubation and consequently a wider window for (inherent) selectivity. In a second step, we write C-rich Pt micro-patterns on SiO2 by focused electron-beam-induced deposition (FEBID), varying the number of FEBID scans at two electron beam acceleration voltages. Subsequently, the localized Pt(C) deposits are pre-cleaned in O2 and overgrown by Ru ALD. Already sub-nanometer-thin Pt(C) patterns, which were supposedly purified into some form of Pt(O x ), acted as very effective activation for the locally restricted, thus area-selective ALD growth of a pure, continuous Ru covering, whereas the SiO2 substratum sufficiently inhibited towards no growth. FEBID at lower electron energy reduced unwanted stray deposition and achieved well-resolved pattern features. We access the nucleation phenomena by utilizing a hybrid metrology approach, which uniquely combines in-situ real-time spectroscopic ellipsometry, in-vacuo x-ray photoelectron spectroscopy, ex-situ high-resolution scanning electron microscopy, and mapping energy-dispersive x-ray spectroscopy.

Safety and utility of magnetic resonance imaging in patients with cardiac implantable electronic devices.

PubMed

Strom, Jordan B; Whelan, Jill B; Shen, Changyu; Zheng, Shuang Qi; Mortele, Koenraad J; Kramer, Daniel B

2017-08-01

Off-label magnetic resonance imaging (MRI) for patients with cardiac implantable electrical devices has been limited owing to concerns about safety and unclear diagnostic and prognostic utility. The purpose of this study was to define major and minor adverse events with off-label MRI scans. We prospectively evaluated patients with non-MRI-conditional cardiac implantable electrical devices referred for MRI scans under a strict clinical protocol. The primary safety outcome was incidence of major adverse events (loss of pacing, inappropriate shock or antitachycardia pacing, need for system revision, or death) or minor adverse events (inappropriate pacing, arrhythmias, power-on-reset events, heating at the generator site, or changes in device parameters at baseline or at 6 months). A total of 189 MRI scans were performed in 123 patients (63.1% [78] men; median age 70 ± 18.5 years; 56.9% [70] patients with implantable cardioverter-defibrillators; 33.3% [41] pacemaker-dependent patients) predominantly for brain or spinal conditions. A minority of scans (22.7% [43]) were performed for urgent or emergent indications. Major adverse events were rare: 1 patient with loss of pacing, no deaths, or system revisions (overall rate 0.5%; 95% confidence interval 0.01-2.91). Minor adverse events were similarly rare (overall rate 1.6%; 95% confidence interval 0.3-4.6). Nearly all studies (98.4% [186]) were interpretable, while 75.1% [142] were determined to change management according to the prespecified criteria. No clinically significant changes were observed in device parameters acutely after MRI or at 6 months as compared with baseline across all patient and device categories. Off-label MRI scans performed under a strict protocol demonstrated excellent short- and medium-term safety while providing interpretable imaging that frequently influenced clinical care. Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Safety and utility of magnetic resonance imaging in patients with cardiac implantable electronic devices

PubMed Central

Strom, Jordan B.; Whelan, Jill B.; Shen, Changyu; Zheng, Shuang Qi; Mortele, Koenraad J.; Kramer, Daniel B.

2017-01-01

BACKGROUND Off-label magnetic resonance imaging (MRI) for patients with cardiac implantable electrical devices has been limited owing to concerns about safety and unclear diagnostic and prognostic utility. OBJECTIVE The purpose of this study was to define major and minor adverse events with off-label MRI scans. METHODS We prospectively evaluated patients with non–MRI-conditional cardiac implantable electrical devices referred for MRI scans under a strict clinical protocol. The primary safety outcome was incidence of major adverse events (loss of pacing, inappropriate shock or antitachycardia pacing, need for system revision, or death) or minor adverse events (inappropriate pacing, arrhythmias, power-on-reset events, heating at the generator site, or changes in device parameters at baseline or at 6 months). RESULTS A total of 189 MRI scans were performed in 123 patients (63.1% [78] men; median age 70 ± 18.5 years; 37.0% [70] patients with implantable cardioverter-defibrillators; 21.8% [41] pacemaker-dependent patients) predominantly for brain or spinal conditions. A minority of scans (22.7% [43]) were performed for urgent or emergent indications. Major adverse events were rare: 1 patient with loss of pacing, no deaths, or system revisions (overall rate 0.5%; 95% confidence interval 0.01–2.91). Minor adverse events were similarly rare (overall rate 1.6%; 95% confidence interval 0.3–4.6). Nearly all studies (98.4% [186]) were interpretable, while 74.9% [142] were determined to change management according to the prespecified criteria. No clinically significant changes were observed in device parameters acutely after MRI or at 6 months as compared with baseline across all patient and device categories. CONCLUSION Off-label MRI scans performed under a strict protocol demonstrated excellent short- and medium-term safety while providing interpretable imaging that frequently influenced clinical care. PMID:28385671

Probing Individual Ice Nucleation Events with Environmental Scanning Electron Microscopy

NASA Astrophysics Data System (ADS)

Wang, Bingbing; China, Swarup; Knopf, Daniel; Gilles, Mary; Laskin, Alexander

2016-04-01

Heterogeneous ice nucleation is one of the processes of critical relevance to a range of topics in the fundamental and the applied science and technologies. Heterogeneous ice nucleation initiated by particles proceeds where microscopic properties of particle surfaces essentially control nucleation mechanisms. Ice nucleation in the atmosphere on particles governs the formation of ice and mixed phase clouds, which in turn influence the Earth's radiative budget and climate. Heterogeneous ice nucleation is still insufficiently understood and poses significant challenges in predictive understanding of climate change. We present a novel microscopy platform allowing observation of individual ice nucleation events at temperature range of 193-273 K and relative humidity relevant for ice formation in the atmospheric clouds. The approach utilizes a home built novel ice nucleation cell interfaced with Environmental Scanning Electron Microscope (IN-ESEM system). The IN-ESEM system is applied for direct observation of individual ice formation events, determining ice nucleation mechanisms, freezing temperatures, and relative humidity onsets. Reported microanalysis of the ice nucleating particles (INP) include elemental composition detected by the energy dispersed analysis of X-rays (EDX), and advanced speciation of the organic content in particles using scanning transmission x-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). The performance of the IN-ESEM system is validated through a set of experiments with kaolinite particles with known ice nucleation propensity. We demonstrate an application of the IN-ESEM system to identify and characterize individual INP within a complex mixture of ambient particles.

Scanning Electron Microscopy (SEM) Procedure for HE Powders on a Zeiss Sigma HD VP SEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zaka, F.

This method describes the characterization of inert and HE materials by the Zeiss Sigma HD VP field emission Scanning Electron Microscope (SEM). The SEM uses an accelerated electron beam to generate high-magnification images of explosives and other materials. It is fitted with five detectors (SE, Inlens, STEM, VPSE, HDBSD) to enable imaging of the sample via different secondary electron signatures, angles, and energies. In addition to imaging through electron detection, the microscope is also fitted with two Oxford Instrument Energy Dispersive Spectrometer (EDS) 80 mm detectors to generate elemental constituent spectra and two-dimensional maps of the material being scanned.

Comparative study of image contrast in scanning electron microscope and helium ion microscope.

PubMed

O'Connell, R; Chen, Y; Zhang, H; Zhou, Y; Fox, D; Maguire, P; Wang, J J; Rodenburg, C

2017-12-01

Images of Ga + -implanted amorphous silicon layers in a 110 n-type silicon substrate have been collected by a range of detectors in a scanning electron microscope and a helium ion microscope. The effects of the implantation dose and imaging parameters (beam energy, dwell time, etc.) on the image contrast were investigated. We demonstrate a similar relationship for both the helium ion microscope Everhart-Thornley and scanning electron microscope Inlens detectors between the contrast of the images and the Ga + density and imaging parameters. These results also show that dynamic charging effects have a significant impact on the quantification of the helium ion microscope and scanning electron microscope contrast. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Utilization of fish bone as adsorbent of Fe3+ ion by controllable removal of its carbonaceous component

NASA Astrophysics Data System (ADS)

Nurhadi, M.; Kusumawardani, R.; Widiyowati, I. I.; Wirhanuddin; Nur, H.

2018-05-01

The performance of fish bone to adsorb Fe3+ ion in solution was studied. Powdered fish bone and carbonized fish bone were used as adsorbent. All absorbents were characterized by X-ray diffraction (XRD), IR spectroscopy, nitrogen adsorption, scanning electron microscopy (SEM) and TG analysis. Powdered fish bone and carbonized fish bone were effective as adsorbent for removing Fe3+ ion in solution. The metal adsorptions of Fe3+ ion were 94 and 98% for powdered fish bone and fish bone which carbonized at 400 and 500 °C.

Investigation on thermo physical characteristics of ethylene glycol based Al:ZnO nanofluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kiruba, R., E-mail: krbranjini@gmail.com, E-mail: drkingson@karunya.edu; George, Ritty; Gopalakrishnan, M.

2015-06-24

The present work describes the experimental aspects of viscosity and thermal conductivity characteristics of nanofluids. Aluminium doped zinc oxide nanostructures were synthesized by chemical precipitation method. Ultrasonic technique is used to disperse the nanostructures in ethylene glycol. Structural and morphological properties of Al doped ZnO nanostructures are characterized using X-ray diffractometer and scanning electron microscopic technique. The effect of concentration and temperature on thermo-physical properties of Al/ZnO nanofluids is also investigated. The experimental results showed there is enhancement in thermal conductivity with rise in temperature which can be utilized for coolant application.

Lamb wave tomographic imaging system for aircraft structural health assessment

NASA Astrophysics Data System (ADS)

Schwarz, Willi G.; Read, Michael E.; Kremer, Matthew J.; Hinders, Mark K.; Smith, Barry T.

1999-01-01

A tomographic imaging system using ultrasonic Lamb waves for the nondestructive inspection of aircraft components such as wings and fuselage is being developed. The computer-based system provides large-area inspection capability by electronically scanning an array of transducers that can be easily attached to flat and curved surface without moving parts. Images of the inspected area are produced in near real time employing a tomographic reconstruction method adapted from seismological applications. Changes in material properties caused by structural flaws such as disbonds, corrosion, and fatigue cracks can be effectively detected and characterized utilizing this fast NDE technique.

Synthesis, characteristics and antimicrobial activity of ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Janaki, A. Chinnammal; Sailatha, E.; Gunasekaran, S.

2015-06-01

The utilization of various plant resources for the bio synthesis of metallic nano particles is called green technology and it does not utilize any harmful protocols. Present study focuses on the green synthesis of ZnO nano particles by Zinc Carbonate and utilizing the bio-components of powder extract of dry ginger rhizome (Zingiber officinale). The ZnO nano crystallites of average size range of 23-26 nm have been synthesized by rapid, simple and eco friendly method. Zinc oxide nano particles were characterized by using X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray spectroscopy (EDX). FTIR spectra confirmed the adsorption of surfactant molecules at the surface of ZnO nanoparticles and the presence of ZnO bonding. Antimicrobial activity of ZnO nano particles was done by well diffusion method against pathogenic organisms like Klebsiella pneumonia, Staphylococcus aureus and Candida albicans and Penicillium notatum. It is observed that the ZnO synthesized in the process has the efficient antimicrobial activity.

Nitrogen-Doped Diamond Film for Optical Investigation of Hemoglobin Concentration

PubMed Central

Majchrowicz, Daria; Kosowska, Monika; Struk, Przemysław; Sobaszek, Michał; Jędrzejewska-Szczerska, Małgorzata

2018-01-01

In this work we present the fabrication and characterization of a diamond film which can be utilized in the construction of optical sensors for the investigation of biological samples. We produced a nitrogen-doped diamond (NDD) film using a microwave plasma enhanced chemical vapor deposition (MWPECVD) system. The NDD film was investigated with the use of scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman spectroscopy. The NDD film was used in the construction of the fiber optic sensor. This sensor is based on the Fabry–Pérot interferometer working in a reflective mode and the NDD film is utilized as a reflective layer of this interferometer. Application of the NDD film allowed us to obtain the sensor of hemoglobin concentration with linear work characteristics with a correlation coefficient (R2) equal to 0.988. PMID:29324715

Fabrication of PDMS-Based Microfluidic Devices: Application for Synthesis of Magnetic Nanoparticles

NASA Astrophysics Data System (ADS)

Thu, Vu Thi; Mai, An Ngoc; Le The Tam; Van Trung, Hoang; Thu, Phung Thi; Tien, Bui Quang; Thuat, Nguyen Tran; Lam, Tran Dai

2016-05-01

In this work, we have developed a convenient approach to synthesize magnetic nanoparticles with relatively high magnetization and controllable sizes. This was realized by combining the traditional co-precipitation method and microfluidic techniques inside microfluidic devices. The device was first designed, and then fabricated using simplified soft-lithography techniques. The device was utilized to synthesize magnetite nanoparticles. The synthesized nanomaterials were thoroughly characterized using field emission scanning electron microscopy and a vibrating sample magnetometer. The results demonstrated that the as-prepared device can be utilized as a simple and effective tool to synthesize magnetic nanoparticles with the sizes less than 10 nm and magnetization more than 50 emu/g. The development of these devices opens new strategies to synthesize nanomaterials with more precise dimensions at narrow size-distribution and with controllable behaviors.

Fast ultra-wideband microwave spectral scanning utilizing photonic wavelength- and time-division multiplexing.

PubMed

Li, Yihan; Kuse, Naoya; Fermann, Martin

2017-08-07

A high-speed ultra-wideband microwave spectral scanning system is proposed and experimentally demonstrated. Utilizing coherent dual electro-optical frequency combs and a recirculating optical frequency shifter, the proposed system realizes wavelength- and time-division multiplexing at the same time, offering flexibility between scan speed and size, weight and power requirements (SWaP). High-speed spectral scanning spanning from ~1 to 8 GHz with ~1.2 MHz spectral resolution is achieved experimentally within 14 µs. The system can be easily scaled to higher bandwidth coverage, faster scanning speed or finer spectral resolution with suitable hardware.

Correction of image drift and distortion in a scanning electron microscopy.

PubMed

Jin, P; Li, X

2015-12-01

Continuous research on small-scale mechanical structures and systems has attracted strong demand for ultrafine deformation and strain measurements. Conventional optical microscope cannot meet such requirements owing to its lower spatial resolution. Therefore, high-resolution scanning electron microscope has become the preferred system for high spatial resolution imaging and measurements. However, scanning electron microscope usually is contaminated by distortion and drift aberrations which cause serious errors to precise imaging and measurements of tiny structures. This paper develops a new method to correct drift and distortion aberrations of scanning electron microscope images, and evaluates the effect of correction by comparing corrected images with scanning electron microscope image of a standard sample. The drift correction is based on the interpolation scheme, where a series of images are captured at one location of the sample and perform image correlation between the first image and the consequent images to interpolate the drift-time relationship of scanning electron microscope images. The distortion correction employs the axial symmetry model of charged particle imaging theory to two images sharing with the same location of one object under different imaging fields of view. The difference apart from rigid displacement between the mentioned two images will give distortion parameters. Three-order precision is considered in the model and experiment shows that one pixel maximum correction is obtained for the employed high-resolution electron microscopic system. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

High-resolution, high-throughput imaging with a multibeam scanning electron microscope.

PubMed

Eberle, A L; Mikula, S; Schalek, R; Lichtman, J; Knothe Tate, M L; Zeidler, D

2015-08-01

Electron-electron interactions and detector bandwidth limit the maximal imaging speed of single-beam scanning electron microscopes. We use multiple electron beams in a single column and detect secondary electrons in parallel to increase the imaging speed by close to two orders of magnitude and demonstrate imaging for a variety of samples ranging from biological brain tissue to semiconductor wafers. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Dynamic scan control in STEM: Spiral scans

DOE PAGES

Lupini, Andrew R.; Borisevich, Albina Y.; Kalinin, Sergei V.; ...

2016-06-13

Here, scanning transmission electron microscopy (STEM) has emerged as one of the foremost techniques to analyze materials at atomic resolution. However, two practical difficulties inherent to STEM imaging are: radiation damage imparted by the electron beam, which can potentially damage or otherwise modify the specimen and slow-scan image acquisition, which limits the ability to capture dynamic changes at high temporal resolution. Furthermore, due in part to scan flyback corrections, typical raster scan methods result in an uneven distribution of dose across the scanned area. A method to allow extremely fast scanning with a uniform residence time would enable imaging atmore » low electron doses, ameliorating radiation damage and at the same time permitting image acquisition at higher frame-rates while maintaining atomic resolution. The practical complication is that rastering the STEM probe at higher speeds causes significant image distortions. Non-square scan patterns provide a solution to this dilemma and can be tailored for low dose imaging conditions. Here, we develop a method for imaging with alternative scan patterns and investigate their performance at very high scan speeds. A general analysis for spiral scanning is presented here for the following spiral scan functions: Archimedean, Fermat, and constant linear velocity spirals, which were tested for STEM imaging. The quality of spiral scan STEM images is generally comparable with STEM images from conventional raster scans, and the dose uniformity can be improved.« less

Dynamic scan control in STEM: Spiral scans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lupini, Andrew R.; Borisevich, Albina Y.; Kalinin, Sergei V.

Here, scanning transmission electron microscopy (STEM) has emerged as one of the foremost techniques to analyze materials at atomic resolution. However, two practical difficulties inherent to STEM imaging are: radiation damage imparted by the electron beam, which can potentially damage or otherwise modify the specimen and slow-scan image acquisition, which limits the ability to capture dynamic changes at high temporal resolution. Furthermore, due in part to scan flyback corrections, typical raster scan methods result in an uneven distribution of dose across the scanned area. A method to allow extremely fast scanning with a uniform residence time would enable imaging atmore » low electron doses, ameliorating radiation damage and at the same time permitting image acquisition at higher frame-rates while maintaining atomic resolution. The practical complication is that rastering the STEM probe at higher speeds causes significant image distortions. Non-square scan patterns provide a solution to this dilemma and can be tailored for low dose imaging conditions. Here, we develop a method for imaging with alternative scan patterns and investigate their performance at very high scan speeds. A general analysis for spiral scanning is presented here for the following spiral scan functions: Archimedean, Fermat, and constant linear velocity spirals, which were tested for STEM imaging. The quality of spiral scan STEM images is generally comparable with STEM images from conventional raster scans, and the dose uniformity can be improved.« less

Expansion of Shockley stacking fault observed by scanning electron microscope and partial dislocation motion in 4H-SiC

NASA Astrophysics Data System (ADS)

Yamashita, Yoshifumi; Nakata, Ryu; Nishikawa, Takeshi; Hada, Masaki; Hayashi, Yasuhiko

2018-04-01

We studied the dynamics of the expansion of a Shockley-type stacking fault (SSF) with 30° Si(g) partial dislocations (PDs) using a scanning electron microscope. We observed SSFs as dark lines (DLs), which formed the contrast at the intersection between the surface and the SSF on the (0001) face inclined by 8° from the surface. We performed experiments at different electron-beam scanning speeds, observing magnifications, and irradiation areas. The results indicated that the elongation of a DL during one-frame scanning depended on the time for which the electron beam irradiated the PD segment in the frame of view. From these results, we derived a formula to express the velocity of the PD using the elongation rate of the corresponding DL during one-frame scanning. We also obtained the result that the elongation velocity of the DL was not influenced by changing the direction in which the electron beam irradiates the PD. From this result, we deduced that the geometrical kink motion of the PD was enhanced by diffusing carriers that were generated by the electron-beam irradiation.

Three-dimensional imaging of adherent cells using FIB/SEM and STEM.

PubMed

Villinger, Clarissa; Schauflinger, Martin; Gregorius, Heiko; Kranz, Christine; Höhn, Katharina; Nafeey, Soufi; Walther, Paul

2014-01-01

In this chapter we describe three different approaches for three-dimensional imaging of electron microscopic samples: serial sectioning transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) tomography, and focused ion beam/scanning electron microscopy (FIB/SEM) tomography. With these methods, relatively large volumes of resin-embedded biological structures can be analyzed at resolutions of a few nm within a reasonable expenditure of time. The traditional method is serial sectioning and imaging the same area in all sections. Another method is TEM tomography that involves tilting a section in the electron beam and then reconstruction of the volume by back projection of the images. When the scanning transmission (STEM) mode is used, thicker sections (up to 1 μm) can be analyzed. The third approach presented here is focused ion beam/scanning electron microscopy (FIB/SEM) tomography, in which a sample is repeatedly milled with a focused ion beam (FIB) and each newly produced block face is imaged with the scanning electron microscope (SEM). This process can be repeated ad libitum in arbitrary small increments allowing 3D analysis of relatively large volumes such as eukaryotic cells. We show that resolution of this approach is considerably improved when the secondary electron signal is used. However, the most important prerequisite for three-dimensional imaging is good specimen preparation. For all three imaging methods, cryo-fixed (high-pressure frozen) and freeze-substituted samples have been used.

A facile synthesis of lipid stabilized gold nanoparticles: a step towards biodegradable biosensors.

PubMed

Abraham, Sinoj; Narine, Suresh S

2011-08-01

A new class of polylactone was successfully synthesized and utilized for the encapsulation and stabilization of gold nanoparticles. Core/shell nanoparticle architecture, in which a layer of this polymer surrounds the nanoparticle core have been investigated both as a means to improve the stability and surface chemistry and as a way of accessing unique physical properties that are not possible from one nano-material alone. Given the fact that only few systems has so far been developed for the encapsulation of nanoparticles, our success in using a new biodegradable biopolymer with inbuilt functionality reveals the robustness of this work. The biodegradability of this polylactone was evaluated using scanning electron microscopy (SEM). The morphology and stability of these gold-polymer hybrids were evaluated by using the transmission electron microscopy (TEM) and UV-VIS spectroscopy.

Morphological study of fluorescent carbon Nanoparticles (F-CNPs) from ground coffee waste soot oxidation by diluted acid

NASA Astrophysics Data System (ADS)

Gea, S.; Tjandra, S.; Joshua, J.; Wirjosentono, B.

2018-02-01

Coffee ground waste utilization for fluorescent carbon nanoparticles (F-CNPs) through soot oxidation with diluted HNO3 has been conducted. Soot was obtained through three different treatments to coffee ground waste; which was burned in furnaceat 550°C and 650°C and directly burned in a heat-proofcontainer. Then they were analyzed morphologically with Scanning Electron Microscope (SEM) instrument. Soot from direct burning indicated the optimum result where it has denser pores compared to other two soots. Soot obtained from direct burning was refluxed in diluted HNO3 for 12 hours to perform the oxidation. Yellowish brown supernatant was later observed which lead to green fluorescent under the UV light. F-CNPs characterization was done in Transmission Electron Microscopy, which showed that 7.4-23.4 nm of particle size were distributed.

Analysis of improvement in performance and design parameters for enhancing resolution in an atmospheric scanning electron microscope.

PubMed

Yoon, Yeo Hun; Kim, Seung Jae; Kim, Dong Hwan

2015-12-01

The scanning electron microscope is used in various fields to go beyond diffraction limits of the optical microscope. However, the electron pathway should be conducted in a vacuum so as not to scatter electrons. The pretreatment of the sample is needed for use in the vacuum. To directly observe large and fully hydrophilic samples without pretreatment, the atmospheric scanning electron microscope (ASEM) is needed. We developed an electron filter unit and an electron detector unit for implementation of the ASEM. The key of the electron filter unit is that electrons are transmitted while air molecules remain untransmitted through the unit. The electron detector unit collected the backscattered electrons. We conducted experiments using the selected materials with Havar foil, carbon film and SiN film. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

High Dynamic Range Pixel Array Detector for Scanning Transmission Electron Microscopy.

PubMed

Tate, Mark W; Purohit, Prafull; Chamberlain, Darol; Nguyen, Kayla X; Hovden, Robert; Chang, Celesta S; Deb, Pratiti; Turgut, Emrah; Heron, John T; Schlom, Darrell G; Ralph, Daniel C; Fuchs, Gregory D; Shanks, Katherine S; Philipp, Hugh T; Muller, David A; Gruner, Sol M

2016-02-01

We describe a hybrid pixel array detector (electron microscope pixel array detector, or EMPAD) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128×128 pixel detector consists of a 500 µm thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit. The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as local sample thickness can be directly determined. This paper describes the detector architecture, data acquisition system, and preliminary results from experiments with 80-200 keV electron beams.

Precision controlled atomic resolution scanning transmission electron microscopy using spiral scan pathways

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sang, Xiahan; Lupini, Andrew R.; Ding, Jilai

Atomic-resolution imaging in an aberration-corrected scanning transmission electron microscope (STEM) can enable direct correlation between atomic structure and materials functionality. The fast and precise control of the STEM probe is, however, challenging because the true beam location deviates from the assigned location depending on the properties of the deflectors. To reduce these deviations, i.e. image distortions, we use spiral scanning paths, allowing precise control of a sub-Å sized electron probe within an aberration-corrected STEM. Although spiral scanning avoids the sudden changes in the beam location (fly-back distortion) present in conventional raster scans, it is not distortion-free. “Archimedean” spirals, with amore » constant angular frequency within each scan, are used to determine the characteristic response at different frequencies. We then show that such characteristic functions can be used to correct image distortions present in more complicated constant linear velocity spirals, where the frequency varies within each scan. Through the combined application of constant linear velocity scanning and beam path corrections, spiral scan images are shown to exhibit less scan distortion than conventional raster scan images. The methodology presented here will be useful for in situ STEM imaging at higher temporal resolution and for imaging beam sensitive materials.« less

Precision controlled atomic resolution scanning transmission electron microscopy using spiral scan pathways

DOE PAGES

Sang, Xiahan; Lupini, Andrew R.; Ding, Jilai; ...

2017-03-08

Atomic-resolution imaging in an aberration-corrected scanning transmission electron microscope (STEM) can enable direct correlation between atomic structure and materials functionality. The fast and precise control of the STEM probe is, however, challenging because the true beam location deviates from the assigned location depending on the properties of the deflectors. To reduce these deviations, i.e. image distortions, we use spiral scanning paths, allowing precise control of a sub-Å sized electron probe within an aberration-corrected STEM. Although spiral scanning avoids the sudden changes in the beam location (fly-back distortion) present in conventional raster scans, it is not distortion-free. “Archimedean” spirals, with amore » constant angular frequency within each scan, are used to determine the characteristic response at different frequencies. We then show that such characteristic functions can be used to correct image distortions present in more complicated constant linear velocity spirals, where the frequency varies within each scan. Through the combined application of constant linear velocity scanning and beam path corrections, spiral scan images are shown to exhibit less scan distortion than conventional raster scan images. The methodology presented here will be useful for in situ STEM imaging at higher temporal resolution and for imaging beam sensitive materials.« less

Characterization of Deposits on Glass Substrate as a Tool in Failure Analysis: The Orbiter Vehicle Columbia Case Study

NASA Technical Reports Server (NTRS)

Olivas, J. D.; Melroy, P.; McDanels, S.; Wallace, T.; Zapata, M. C.

2006-01-01

In connection with the accident investigation of the space shuttle Columbia, an analysis methodology utilizing well established microscopic and spectroscopic techniques was implemented for evaluating the environment to which the exterior fused silica glass was exposed. Through the implementation of optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, and electron diffraction, details emerged regarding the manner in which a charred metallic deposited layer formed on top of the exposed glass. Due to nature of the substrate and the materials deposited, the methodology proved to allow for a more detailed analysis of the vehicle breakup. By contrast, similar analytical methodologies on metallic substrates have proven to be challenging due to strong potential for error resulting from substrate contamination. This information proved to be valuable to not only those involved in investigating the break up of Columbia, but also provides a potential guide for investigating future high altitude and high energy accidents.

Tip/tilt-compensated through-focus scanning optical microscopy

NASA Astrophysics Data System (ADS)

Lee, Jun Ho; Park, Jun Hyung; Jeong, Dohwan; Shin, Eun Ji; Park, Chris

2016-11-01

Through-Focus Optical Microscopy (TSOM), with nanometer scale lateral and vertical sensitivity matching those of scanning electron microscopy, has been demonstrated to be utilized for 3D inspection and metrology. There have been sensitivity and instability issues in acquiring through-focus images because TSOM 3D information is indirectly extracted by differentiating a target TSOM image from reference TSOM images. This paper first reports on the optical axis instability that occurs during the scanning process of TSOM when implemented in an existing patterned wafer inspection tool by moving the wafer plane; this is followed by quantitative confirmation of the optical/mechanical instability using a new TSOM tool on an optical bench with a Shack-Hartmann wavefront sensor and a tip/tilt sensor. Then, this paper proposes two tip/tilt compensated TSOM optical acquisition methods that can be applied with adaptive optics. The first method simply adopts a tip/tilt mirror with a quad cell in a simple closed loop, while the second method adopts a highorder deformable mirror with a Shack-Hartmann sensor. The second method is able to correct high-order residual aberrations as well as to perform through-focus scanning without z-axis movement, while the first method is easier to implement in pre-existing wafer inspection systems with only minor modification.

Fast and low-dose computed laminography using compressive sensing based technique

NASA Astrophysics Data System (ADS)

Abbas, Sajid; Park, Miran; Cho, Seungryong

2015-03-01

Computed laminography (CL) is well known for inspecting microstructures in the materials, weldments and soldering defects in high density packed components or multilayer printed circuit boards. The overload problem on x-ray tube and gross failure of the radio-sensitive electronics devices during a scan are among important issues in CL which needs to be addressed. The sparse-view CL can be one of the viable option to overcome such issues. In this work a numerical aluminum welding phantom was simulated to collect sparsely sampled projection data at only 40 views using a conventional CL scanning scheme i.e. oblique scan. A compressive-sensing inspired total-variation (TV) minimization algorithm was utilized to reconstruct the images. It is found that the images reconstructed using sparse view data are visually comparable with the images reconstructed using full scan data set i.e. at 360 views on regular interval. We have quantitatively confirmed that tiny structures such as copper and tungsten slags, and copper flakes in the reconstructed images from sparsely sampled data are comparable with the corresponding structure present in the fully sampled data case. A blurring effect can be seen near the edges of few pores at the bottom of the reconstructed images from sparsely sampled data, despite the overall image quality is reasonable for fast and low-dose NDT.

The utility of computed tomography in the management of fever and neutropenia in pediatric oncology.

PubMed

Rao, Avani D; Sugar, Elizabeth A; Barrett, Neil; Mahesh, Mahadevappa; Arceci, Robert J

2015-10-01

Despite the frequent use and radiation exposure of computed tomography (CT) scans, there is little information on patterns of CT use and their utility in the management of pediatric patients with fever and neutropenia (FN). We examined the contribution of either the commonly employed pan-CT (multiple anatomical locations) or targeted CT (single location) scanning to identify possible infectious etiologies in this challenging clinical scenario. Procedure Pediatric patients with an underlying malignancy admitted for fever (temperature ≥ 38.3 °C) and an absolute neutrophil count <500 cells/μL from 2003-2009 were included. Risk factors associated with utilization, results, and effects on clinical management of CT scans were identified. Results Charts for 635 admissions for FN from 263 patients were reviewed. Overall, 139 (22%) admissions (93 individuals) had at least one scan. Of 188 scans, 103 (55%) were pan-scans. Changes in management were most strongly associated with the identification of evidence consistent with infection (OR = 12.64, 95% CI: 5.05-31.60, P < 0.001). Seventy-eight (41%) of all CT scans led to a change in clinical management, most commonly relating to use of antibiotic (N = 41, 53%) or antifungal/antiviral medications (N = 33, 42%). The odds of a change in clinical management did not differ for those receiving a pan-scan compared to those receiving a targeted scan (OR = 1.23; 95% CI, 0.61-2.46; P = 0.57). Conclusions When CT is clinically indicated, it is important for clinicians to strongly consider utilizing a targeted scan to reduce radiation exposure to patients as well as to decrease costs without compromising care. © 2015 Wiley Periodicals, Inc.

Large area fabrication of plasmonic nanoparticle grating structure by conventional scanning electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Rai, V. N.

Plasmonic nanoparticle grating (PNG) structure of different periods has been fabricated by electron beam lithography using silver halide based transmission electron microscope film as a substrate. Conventional scanning electron microscope is used as a fabrication tool for electron beam lithography. Optical microscope and energy dispersive spectroscopy (EDS) have been used for its morphological and elemental characterization. Optical characterization is performed by UV-Vis absorption spectroscopic technique.

Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope.

PubMed

Li, Meng; Xu, Chunkai; Zhang, Panke; Li, Zhean; Chen, Xiangjun

2016-08-01

We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam.

Analysis of the EBT3 Gafchromic film irradiated with 6 MV photons and 6 MeV electrons using reflective mode scanners.

PubMed

Farah, Nicolas; Francis, Ziad; Abboud, Marie

2014-09-01

We explore in our study the effects of electrons and X-rays irradiations on the newest version of the Gafchromic EBT3 film. Experiments are performed using the Varian "TrueBeam 1.6" medical accelerator delivering 6 MV X-ray photons and 6 MeV electron beams as desired. The main interest is to compare the responses of EBT3 films exposed to two separate beams of electrons and photons, for radiation doses ranging up to 500 cGy. The analysis is done on a flatbed EPSON 10000 XL scanner and cross checked on a HP Scanjet 4850 scanner. Both scanners are used in reflection mode taking into account landscape and portrait scanning positions. After thorough verifications, the reflective scanning method can be used on EBT3 as an economic alternative to the transmission method which was also one of the goals of this study. A comparison is also done between single scan configuration including all samples in a single A4 (HP) or A3 (EPSON) format area and multiple scan procedure where each sample is scanned separately on its own. The images analyses are done using the ImageJ software. Results show significant influence of the scanning configuration but no significant differences between electron and photon irradiations for both single and multiple scan configurations. In conclusion, the film provides a reliable relative dose measurement method for electrons and photons irradiations in the medical field applications. Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Writing silica structures in liquid with scanning transmission electron microscopy.

PubMed

van de Put, Marcel W P; Carcouët, Camille C M C; Bomans, Paul H H; Friedrich, Heiner; de Jonge, Niels; Sommerdijk, Nico A J M

2015-02-04

Silica nanoparticles are imaged in solution with scanning transmission electron microscopy (STEM) using a liquid cell with silicon nitride (SiN) membrane windows. The STEM images reveal that silica structures are deposited in well-defined patches on the upper SiN membranes upon electron beam irradiation. The thickness of the deposits is linear with the applied electron dose. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) demonstrate that the deposited patches are a result of the merging of the original 20 nm-diameter nanoparticles, and that the related surface roughness depends on the electron dose rate used. Using this approach, sub-micrometer scale structures are written on the SiN in liquid by controlling the electron exposure as function of the lateral position. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Examination of Surveyor 3 parts with the scanning electron microscope and electron microprobe

NASA Technical Reports Server (NTRS)

Chodos, A. A.; Devaney, J. R.; Evens, K. C.

1972-01-01

Two screws and two washers, several small chips of tubing, and a fiber removed from a third screw were examined with the scanning electron microscope and the electron microprobe. The purpose of the examination was to determine the nature of the material on the surface of these samples and to search for the presence of meteoritic material.

Observations on the Role of Hydrogen in Facet Formation in Near-alpha Titanium (Preprint)

DTIC Science & Technology

2011-05-01

using quantitative tilt fractography and electron backscatter diffraction while facet topography was examined using ultra high resolution scanning...quantitative tilt fractography and electron backscatter diffraction while facet topography was examined using ultra high resolution scanning electron...tilt fractography / electron backscatter diffraction (EBSD) technique in which both the crystallographic orientation of the fractured grain and the

Nondestructive determination of the depth of planar p-n junctions by scanning electron microscopy

NASA Technical Reports Server (NTRS)

Chi, J.-Y.; Gatos, H. C.

1977-01-01

A method was developed for measuring nondestructively the depth of planar p-n junctions in simple devices as well as in integrated-circuit structures with the electron-beam induced current (EBIC) by scanning parallel to the junction in a scanning electron microscope (SEM). The results were found to be in good agreement with those obtained by the commonly used destructive method of lapping at an angle to the junction and staining to reveal the junction.

Use of scanning electron microscopy and microanalysis to determine chloride content of concrete and raw materials.

DOT National Transportation Integrated Search

2013-02-01

Standard sample sets of cement and mortar formulations with known levels of Cl as well as concrete samples subject to Cl diffusion were all prepared for and analyzed with scanning electron microscopy (SEM) and electron microprobe (EPMA). Using x-ray ...

Electronically-Scanned Pressure Sensors

NASA Technical Reports Server (NTRS)

Coe, C. F.; Parra, G. T.; Kauffman, R. C.

1984-01-01

Sensors not pneumatically switched. Electronic pressure-transducer scanning system constructed in modular form. Pressure transducer modules and analog to digital converter module small enough to fit within cavities of average-sized wind-tunnel models. All switching done electronically. Temperature controlled environment maintained within sensor modules so accuracy maintained while ambient temperature varies.

41 CFR 301-71.201 - What are the reviewing official's responsibilities?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 41 Public Contracts and Property Management 4 2013-07-01 2012-07-01 true What are the reviewing official's responsibilities? 301-71.201 Section 301-71.201 Public Contracts and Property Management Federal... implements electronic scanning, the electronic travel claim includes scanned electronic images of such...

41 CFR 301-71.201 - What are the reviewing official's responsibilities?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 41 Public Contracts and Property Management 4 2014-07-01 2014-07-01 false What are the reviewing official's responsibilities? 301-71.201 Section 301-71.201 Public Contracts and Property Management Federal... implements electronic scanning, the electronic travel claim includes scanned electronic images of such...

41 CFR 301-71.201 - What are the reviewing official's responsibilities?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 41 Public Contracts and Property Management 4 2012-07-01 2012-07-01 false What are the reviewing official's responsibilities? 301-71.201 Section 301-71.201 Public Contracts and Property Management Federal... implements electronic scanning, the electronic travel claim includes scanned electronic images of such...

41 CFR 301-71.201 - What are the reviewing official's responsibilities?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 41 Public Contracts and Property Management 4 2011-07-01 2011-07-01 false What are the reviewing official's responsibilities? 301-71.201 Section 301-71.201 Public Contracts and Property Management Federal... implements electronic scanning, the electronic travel claim includes scanned electronic images of such...

Coexistence of two electronic nano-phases on a CH 3NH 3PbI 3–xCl x surface observed in STM measurements

DOE PAGES

Yost, Andrew J.; Pimachev, Artem; Ho, Chun -Chih; ...

2016-10-10

Scanning tunneling microscopy is utilized to investigate the local density of states of a CH 3NH 3PbI 3-xCl x perovskite in cross-sectional geometry. Two electronic phases, 10-20 nm in size, with different electronic properties inside the CH 3NH 3PbI 3-xCl x perovskite layer are observed by the dI/ dV mapping and point spectra. A power law dependence of the dI/dV point spectra is revealed. In addition, the distinct electronic phases are found to have preferential orientations close to the normal direction of the film surface. Density functional theory calculations indicate that the observed electronic phases are associated with local deviationmore » of I/Cl ratio, rather than different orientations of the electric dipole moments in the ferroelectric phases. Furthermore, by comparing the calculated results with experimental data we conclude that phase A (lower contrast in dI/dV mapping at -2.0 V bias) contains a lower I/Cl ratio than that in phase B (higher contrast in dI/dV).« less

Characterizing the Three-Dimensional Structure of Block Copolymers via Sequential Infiltration Synthesis and Scanning Transmission Electron Tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Segal-Peretz, Tamar; Winterstein, Jonathan; Doxastakis, Manolis

Understanding and controlling the three-dimensional structure of block copolymer (BCP) thin films is critical for utilizing these materials for sub-20 nm nanopatterning in semiconductor devices, as well as in membranes and solar cell applications. Combining an atomic layer deposition (ALD) based technique for enhancing the contrast of BCPs in transmission electron microscopy (TEM) together with scanning TEM (STEM) tomography reveals and characterizes the three-dimensional structures of poly(styrene-block-methyl methacrylate) (PS-b-PMMA) thin films with great clarity. Sequential infiltration synthesis (SIS), a block-selective technique for growing inorganic materials in BCPs films in ALD, and an emerging tool for enhancing the etch contrast ofmore » BCPs, was harnessed to significantly enhance the high-angle scattering from the polar domains of BCP films in the TEM. The power of combining SIS and STEM tomography for three dimensional (3D) characterization of BCPs films was demonstrated with the following cases: self-assembled cylindrical, lamellar, and spherical PS-PMMA thin films. In all cases, STEM tomography has revealed 3D structures that were hidden underneath the surface, including: 1) the 3D structure of defects in cylindrical and lamellar phases, 2) non-perpendicular 3D surface of grain boundaries in the cylindrical phase, and 3) the 3D arrangement of spheres in body centered cubic (BCC) and hexagonal closed pack (HCP) morphologies in the spherical phase. The 3D data of the spherical morphologies was compared to coarse-grained simulations and assisted in validating the simulations’ parameters. STEM tomography of SIS-treated BCP films enables the characterization of the exact structure used for pattern transfer, and can lead to better understating of the physics which is utilized in BCP lithography.« less

Cellulose decomposition and larval biomass production from the co-digestion of dairy manure and chicken manure by mini-livestock (Hermetia illucens L.).

PubMed

Rehman, Kashif Ur; Cai, Minmin; Xiao, Xiaopeng; Zheng, Longyu; Wang, Hui; Soomro, Abdul Aziz; Zhou, Yusha; Li, Wu; Yu, Ziniu; Zhang, Jibin

2017-07-01

World trends toward the modern dairies intensification on large production units cause massive animal manure production and accumulation. Improper handling of manure produced by industrial farm operation greatly deteriorates the major environmental media including air, water and soil. The black soldier fly utilizes organic waste and converts it into larvae biomass to be used as livestock feed and into residues to be used as bio-fertilizer. However, due to the high ratio of cellulose, hemicellulose and lignin in dairy manure, this conversion is difficult. Therefore, dairy manure treated with chicken manure was digested by Hermetia illucens. In this paper, we found that the co-digestion process significantly enhanced the larval production, waste mass reduction, rate of larvae conversion, feed conversion ratio, nutrient reduction and fibers utilization. Whereas 40% dairy manure and 60% chicken manure group show better results than other manure mixtures and had a significantly increased the cellulose consumption by 61.19%, hemicellulose consumption by 53.22% and lignin consumption by 42.23% compared with 49.89%, 49.77% and 31.95%, respectively, in the dairy-only manure group. Finally, scanning electron microscopy was used to analyze the structural changes of dairy manure, chicken manure and their co-digestion mixtures. The scan electron microscopy showed the deterioration in the structure of dairy and chicken manure fibers by Hermetia illucens. Moreover, the carbon-nitrogen ratio was decreased in all end products of post vermicomposting. The results suggest that the co-digestion of 40% dairy manure with 60% chicken manure is an appropriate proportion for dairy manure management with the black soldier fly. Copyright © 2017 Elsevier Ltd. All rights reserved.

The co-evolution of microstructure features in self-ion irradiated HT9 at very high damage levels

NASA Astrophysics Data System (ADS)

Getto, E.; Vancoevering, G.; Was, G. S.

2017-02-01

Understanding the void swelling and phase evolution of reactor structural materials at very high damage levels is essential to maintaining safety and longevity of components in Gen IV fast reactors. A combination of ion irradiation and modeling was utilized to understand the microstructure evolution of ferritic-martensitic alloy HT9 at high dpa. Self-ion irradiation experiments were performed on alloy HT9 to determine the co-evolution of voids, dislocations and precipitates up to 650 dpa at 460 °C. Modeling of microstructure evolution was conducted using the modified Radiation Induced Microstructure Evolution (RIME) model, which utilizes a mean field rate theory approach with grouped cluster dynamics. Irradiations were performed with 5 MeV raster-scanned Fe2+ ions on samples pre-implanted with 10 atom parts per million He. The swelling, dislocation and precipitate evolution at very high dpa was determined using Analytical Electron Microscopy in Scanning Transmission Electron Microscopy (STEM) mode. Experimental results were then interpreted using the RIME model. A microstructure consisting only of dislocations and voids is insufficient to account for the swelling evolution observed experimentally at high damage levels in a complicated microstructure such as irradiated alloy HT9. G phase was found to have a minimal effect on either void or dislocation evolution. M2X played two roles; a variable biased sink for defects, and as a vehicle for removal of carbon from solution, thus promoting void growth. When accounting for all microstructure interactions, swelling at high damage levels is a dynamic process that continues to respond to other changes in the microstructure as long as they occur.

Vertically aligned carbon nanotubes/carbon fiber paper composite to support Pt nanoparticles for direct methanol fuel cell application

NASA Astrophysics Data System (ADS)

Zhang, Jing; Yi, Xi-bin; Liu, Shuo; Fan, Hui-Li; Ju, Wei; Wang, Qi-Chun; Ma, Jie

2017-03-01

Vertically aligned carbon nanotubes (VACNTs) grown on carbon fiber paper (CFP) by plasma enhanced chemical vapor deposition is introduced as a catalyst support material for direct methanol fuel cells (DMFCs). Well dispersed Pt nanoparticles on VACNTs surface are prepared by impregnation-reduction method. The VACNTs on CFP possess well-maintained alignment, large surface area and good electrical conductivity, which leading to the formation of Pt particles with a smaller size and enhance the Pt utilization rate. The structure and nature of resulting Pt/VACNTs/CFP catalysts for methanol oxidation are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and scanning electron microscope (SEM). With the aid of VACNTs, well-dispersed Pt catalysts enable the reversibly rapid redox kinetic since electron transport efficiently passes through a one-dimensional pathway, which leads to enhance the catalytic activity and Pt utilization rate. Compared with the Pt/XC-72/CFP electrode, the electrochemical measurements results display that the Pt/VACNTs/CFP catalyst shows much higher electrocatalytic activity and better stability for methanol oxidation. In addition, the oxidation current from 200 to 1200 s decayed more slowly for the Pt/VACNTs/CFP than that of the Pt/XC-72/CFP catalysts, indicating less accumulation of adsorbed CO species. All those results imply that the Pt/VACNTs/CFP has a great potential for applications in DMFCs.

Chemical mapping and quantification at the atomic scale by scanning transmission electron microscopy.

PubMed

Chu, Ming-Wen; Chen, Cheng Hsuan

2013-06-25

With innovative modern material-growth methods, a broad spectrum of fascinating materials with reduced dimensions-ranging from single-atom catalysts, nanoplasmonic and nanophotonic materials to two-dimensional heterostructural interfaces-is continually emerging and extending the new frontiers of materials research. A persistent central challenge in this grand scientific context has been the detailed characterization of the individual objects in these materials with the highest spatial resolution, a problem prompting the need for experimental techniques that integrate both microscopic and spectroscopic capabilities. To date, several representative microscopy-spectroscopy combinations have become available, such as scanning tunneling microscopy, tip-enhanced scanning optical microscopy, atom probe tomography, scanning transmission X-ray microscopy, and scanning transmission electron microscopy (STEM). Among these tools, STEM boasts unique chemical and electronic sensitivity at unparalleled resolution. In this Perspective, we elucidate the advances in STEM and chemical mapping applications at the atomic scale by energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy with a focus on the ultimate challenge of chemical quantification with atomic accuracy.

Publications - GMC 357 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 357 Publication Details Title: Thin Section and Scanning Electron Microscopy summary Laboratories, Inc., 2008, Thin Section and Scanning Electron Microscopy summary photographs from plugs taken

Effect of Homogenization on Microstructure Characteristics, Corrosion and Biocompatibility of Mg-Zn-Mn-xCa Alloys

PubMed Central

Li, Jingyuan; Lai, Huiying; Xu, Yuzhao

2018-01-01

The corrosion behaviors of Mg-2Zn-0.2Mn-xCa (denoted as MZM-xCa alloys) in homogenization state have been investigated by immersion test and electrochemical techniques in a simulated physiological condition. The microstructure features were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA), and the corrosion mechanism was illustrated using atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and confocal laser scanning microscopy (CLSM). The electrochemical and immersion test verify the MZM-0.38% Ca owns the best corrosion performance with the corrosion rate of 6.27 mm/year. Furthermore, the film layer of MZM-0.38% Ca is more compact and denser than that of others. This improvement could be associated with the combined effects of the suitable content of Zn/Ca dissolving into the α-Mg matrix and the modification of Ca-containing compounds by heat-treatment. However, the morphologies were transformed from uniform corrosion to localized pitting corrosion with Ca further addition. It could be explained that the excessive Ca addition can strengthen the nucleation driving force for the second phase formation, and the large volumes fraction of micro-galvanic present interface sites accelerate the nucleation driving force for corrosion propagation. In addition, in vitro biocompatibility tests also show the MZM-0.38% Ca was safe to bone mesenchymal stem cells (BMSCs) and was promising to be utilized as implant materials. PMID:29389894

Direct Observation of Protein Microcrystals in Crystallization Buffer by Atmospheric Scanning Electron Microscopy

PubMed Central

Maruyama, Yuusuke; Ebihara, Tatsuhiko; Nishiyama, Hidetoshi; Konyuba, Yuji; Senda, Miki; Numaga-Tomita, Takuro; Senda, Toshiya; Suga, Mitsuo; Sato, Chikara

2012-01-01

X-ray crystallography requires high quality crystals above a given size. This requirement not only limits the proteins to be analyzed, but also reduces the speed of the structure determination. Indeed, the tertiary structures of many physiologically important proteins remain elusive because of the so-called “crystallization bottleneck”. Once microcrystals have been obtained, crystallization conditions can be optimized to produce bigger and better crystals. However, the identification of microcrystals can be difficult due to the resolution limit of optical microscopy. Electron microscopy has sometimes been utilized instead, with the disadvantage that the microcrystals usually must be observed in vacuum, which precludes the usage for crystal screening. The atmospheric scanning electron microscope (ASEM) allows samples to be observed in solution. Here, we report the use of this instrument in combination with a special thin-membrane dish with a crystallization well. It was possible to observe protein crystals of lysozyme, lipase B and a histone chaperone TAF-Iβ in crystallization buffers, without the use of staining procedures. The smallest crystals observed with ASEM were a few μm in width, and ASEM can be used with non-transparent solutions. Furthermore, the growth of salt crystals could be monitored in the ASEM, and the difference in contrast between salt and protein crystals made it easy to distinguish between these two types of microcrystals. These results indicate that the ASEM could be an important new tool for the screening of protein microcrystals. PMID:22949879

Direct observation of protein microcrystals in crystallization buffer by atmospheric scanning electron microscopy.

PubMed

Maruyama, Yuusuke; Ebihara, Tatsuhiko; Nishiyama, Hidetoshi; Konyuba, Yuji; Senda, Miki; Numaga-Tomita, Takuro; Senda, Toshiya; Suga, Mitsuo; Sato, Chikara

2012-01-01

X-ray crystallography requires high quality crystals above a given size. This requirement not only limits the proteins to be analyzed, but also reduces the speed of the structure determination. Indeed, the tertiary structures of many physiologically important proteins remain elusive because of the so-called "crystallization bottleneck". Once microcrystals have been obtained, crystallization conditions can be optimized to produce bigger and better crystals. However, the identification of microcrystals can be difficult due to the resolution limit of optical microscopy. Electron microscopy has sometimes been utilized instead, with the disadvantage that the microcrystals usually must be observed in vacuum, which precludes the usage for crystal screening. The atmospheric scanning electron microscope (ASEM) allows samples to be observed in solution. Here, we report the use of this instrument in combination with a special thin-membrane dish with a crystallization well. It was possible to observe protein crystals of lysozyme, lipase B and a histone chaperone TAF-Iβ in crystallization buffers, without the use of staining procedures. The smallest crystals observed with ASEM were a few μm in width, and ASEM can be used with non-transparent solutions. Furthermore, the growth of salt crystals could be monitored in the ASEM, and the difference in contrast between salt and protein crystals made it easy to distinguish between these two types of microcrystals. These results indicate that the ASEM could be an important new tool for the screening of protein microcrystals.

Improving Secondary Ion Mass Spectrometry Image Quality with Image Fusion

PubMed Central

Tarolli, Jay G.; Jackson, Lauren M.; Winograd, Nicholas

2014-01-01

The spatial resolution of chemical images acquired with cluster secondary ion mass spectrometry (SIMS) is limited not only by the size of the probe utilized to create the images, but also by detection sensitivity. As the probe size is reduced to below 1 µm, for example, a low signal in each pixel limits lateral resolution due to counting statistics considerations. Although it can be useful to implement numerical methods to mitigate this problem, here we investigate the use of image fusion to combine information from scanning electron microscope (SEM) data with chemically resolved SIMS images. The advantage of this approach is that the higher intensity and, hence, spatial resolution of the electron images can help to improve the quality of the SIMS images without sacrificing chemical specificity. Using a pan-sharpening algorithm, the method is illustrated using synthetic data, experimental data acquired from a metallic grid sample, and experimental data acquired from a lawn of algae cells. The results show that up to an order of magnitude increase in spatial resolution is possible to achieve. A cross-correlation metric is utilized for evaluating the reliability of the procedure. PMID:24912432

3D Buried Utility Location Using A Marching-Cross-Section Algorithm for Multi-Sensor Data Fusion

PubMed Central

Dou, Qingxu; Wei, Lijun; Magee, Derek R.; Atkins, Phil R.; Chapman, David N.; Curioni, Giulio; Goddard, Kevin F.; Hayati, Farzad; Jenks, Hugo; Metje, Nicole; Muggleton, Jennifer; Pennock, Steve R.; Rustighi, Emiliano; Swingler, Steven G.; Rogers, Christopher D. F.; Cohn, Anthony G.

2016-01-01

We address the problem of accurately locating buried utility segments by fusing data from multiple sensors using a novel Marching-Cross-Section (MCS) algorithm. Five types of sensors are used in this work: Ground Penetrating Radar (GPR), Passive Magnetic Fields (PMF), Magnetic Gradiometer (MG), Low Frequency Electromagnetic Fields (LFEM) and Vibro-Acoustics (VA). As part of the MCS algorithm, a novel formulation of the extended Kalman Filter (EKF) is proposed for marching existing utility tracks from a scan cross-section (scs) to the next one; novel rules for initializing utilities based on hypothesized detections on the first scs and for associating predicted utility tracks with hypothesized detections in the following scss are introduced. Algorithms are proposed for generating virtual scan lines based on given hypothesized detections when different sensors do not share common scan lines, or when only the coordinates of the hypothesized detections are provided without any information of the actual survey scan lines. The performance of the proposed system is evaluated with both synthetic data and real data. The experimental results in this work demonstrate that the proposed MCS algorithm can locate multiple buried utility segments simultaneously, including both straight and curved utilities, and can separate intersecting segments. By using the probabilities of a hypothesized detection being a pipe or a cable together with its 3D coordinates, the MCS algorithm is able to discriminate a pipe and a cable close to each other. The MCS algorithm can be used for both post- and on-site processing. When it is used on site, the detected tracks on the current scs can help to determine the location and direction of the next scan line. The proposed “multi-utility multi-sensor” system has no limit to the number of buried utilities or the number of sensors, and the more sensor data used, the more buried utility segments can be detected with more accurate location and orientation. PMID:27827836

3D Buried Utility Location Using A Marching-Cross-Section Algorithm for Multi-Sensor Data Fusion.

PubMed

Dou, Qingxu; Wei, Lijun; Magee, Derek R; Atkins, Phil R; Chapman, David N; Curioni, Giulio; Goddard, Kevin F; Hayati, Farzad; Jenks, Hugo; Metje, Nicole; Muggleton, Jennifer; Pennock, Steve R; Rustighi, Emiliano; Swingler, Steven G; Rogers, Christopher D F; Cohn, Anthony G

2016-11-02

We address the problem of accurately locating buried utility segments by fusing data from multiple sensors using a novel Marching-Cross-Section (MCS) algorithm. Five types of sensors are used in this work: Ground Penetrating Radar (GPR), Passive Magnetic Fields (PMF), Magnetic Gradiometer (MG), Low Frequency Electromagnetic Fields (LFEM) and Vibro-Acoustics (VA). As part of the MCS algorithm, a novel formulation of the extended Kalman Filter (EKF) is proposed for marching existing utility tracks from a scan cross-section (scs) to the next one; novel rules for initializing utilities based on hypothesized detections on the first scs and for associating predicted utility tracks with hypothesized detections in the following scss are introduced. Algorithms are proposed for generating virtual scan lines based on given hypothesized detections when different sensors do not share common scan lines, or when only the coordinates of the hypothesized detections are provided without any information of the actual survey scan lines. The performance of the proposed system is evaluated with both synthetic data and real data. The experimental results in this work demonstrate that the proposed MCS algorithm can locate multiple buried utility segments simultaneously, including both straight and curved utilities, and can separate intersecting segments. By using the probabilities of a hypothesized detection being a pipe or a cable together with its 3D coordinates, the MCS algorithm is able to discriminate a pipe and a cable close to each other. The MCS algorithm can be used for both post- and on-site processing. When it is used on site, the detected tracks on the current scs can help to determine the location and direction of the next scan line. The proposed "multi-utility multi-sensor" system has no limit to the number of buried utilities or the number of sensors, and the more sensor data used, the more buried utility segments can be detected with more accurate location and orientation.

Microcircuit testing and fabrication, using scanning electron microscopes

NASA Technical Reports Server (NTRS)

Nicolas, D. P.

1975-01-01

Scanning electron microscopes are used to determine both user-induced damages and manufacturing defects subtle enough to be missed by conventional light microscopy. Method offers greater depth of field and increased working distances.

Imaging of high-angle annular dark-field scanning transmission electron microscopy and observations of GaN-based violet laser diodes.

PubMed

Shiojiri, M; Saijo, H

2006-09-01

The first part of this paper is devoted to physics, to explain high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging and to interpret why HAADF-STEM imaging is incoherent, instructing a strict definition of interference and coherence of electron waves. Next, we present our recent investigations of InGaN/GaN multiple quantum wells and AlGaN/GaN strained-layer superlattice claddings in GaN-based violet laser diodes, which have been performed by HAADF-STEM and high-resolution field-emission gun scanning electron microscopy.

Scanning electron microscope observation of dislocations in semiconductor and metal materials.

PubMed

Kuwano, Noriyuki; Itakura, Masaru; Nagatomo, Yoshiyuki; Tachibana, Shigeaki

2010-08-01

Scanning electron microscope (SEM) image contrasts have been investigated for dislocations in semiconductor and metal materials. It is revealed that single dislocations can be observed in a high contrast in SEM images formed by backscattered electrons (BSE) under the condition of a normal configuration of SEM. The BSE images of dislocations were compared with those of the transmission electron microscope and scanning transmission electron microscope (STEM) and the dependence of BSE image contrast on the tilting of specimen was examined to discuss the origin of image contrast. From the experimental results, it is concluded that the BSE images of single dislocations are attributed to the diffraction effect and related with high-angle dark-field images of STEM.

Attainment of 40.5 pm spatial resolution using 300 kV scanning transmission electron microscope equipped with fifth-order aberration corrector.

PubMed

Morishita, Shigeyuki; Ishikawa, Ryo; Kohno, Yuji; Sawada, Hidetaka; Shibata, Naoya; Ikuhara, Yuichi

2018-02-01

The achievement of a fine electron probe for high-resolution imaging in scanning transmission electron microscopy requires technological developments, especially in electron optics. For this purpose, we developed a microscope with a fifth-order aberration corrector that operates at 300 kV. The contrast flat region in an experimental Ronchigram, which indicates the aberration-free angle, was expanded to 70 mrad. By using a probe with convergence angle of 40 mrad in the scanning transmission electron microscope at 300 kV, we attained the spatial resolution of 40.5 pm, which is the projected interatomic distance between Ga-Ga atomic columns of GaN observed along [212] direction.

Note: Electron energy spectroscopy mapping of surface with scanning tunneling microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Meng; Xu, Chunkai, E-mail: xuck@ustc.edu.cn, E-mail: xjun@ustc.edu.cn; Zhang, Panke

We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than themore » size of the incident electron beam.« less

Measurement of Strain and Stress Distributions in Structural Materials by Electron Moiré Method

NASA Astrophysics Data System (ADS)

Kishimoto, Satoshi; Xing, Yougming; Tanaka, Yoshihisa; Kagawa, Yutaka

A method for measuring the strain and stress distributions in structural materials has been introduced. Fine model grids were fabricated by electron beam lithography, and an electron beam scan by a scanning electron microscope (SEM) was used as the master grid. Exposure of the electron beam scan onto the model grid in an SEM produced the electron beam moiré fringes of bright and dark parts caused by the different amounts of the secondary electrons per a primary electron. For demonstration, the micro-creep deformation of pure copper was observed. The creep strain distribution and the grain boundary sliding were analyzed. The residual strain and stress at the interface between a fiber and a matrix of a fiber reinforced plastic (FRP) were measured using the pushing-out test and this electron moiré method. Also, a non-uniform deformation around the boundary of 3-point bended laminated steel was observed and the strain distribution analyzed.

Insights into radiation damage from atomic resolution scanning transmission electron microscopy imaging of mono-layer CuPcCl16 films on graphene.

PubMed

Mittelberger, Andreas; Kramberger, Christian; Meyer, Jannik C

2018-03-19

Atomically resolved images of monolayer organic crystals have only been obtained with scanning probe methods so far. On the one hand, they are usually prepared on surfaces of bulk materials, which are not accessible by (scanning) transmission electron microscopy. On the other hand, the critical electron dose of a monolayer organic crystal is orders of magnitudes lower than the one for bulk crystals, making (scanning) transmission electron microscopy characterization very challenging. In this work we present an atomically resolved study on the dynamics of a monolayer CuPcCl 16 crystal under the electron beam as well as an image of the undamaged molecules obtained by low-dose electron microscopy. The results show the dynamics and the radiation damage mechanisms in the 2D layer of this material, complementing what has been found for bulk crystals in earlier studies. Furthermore, being able to image the undamaged molecular crystal allows the characterization of new composites consisting of 2D materials and organic molecules.

Surface topography characterization using 3D stereoscopic reconstruction of SEM images

NASA Astrophysics Data System (ADS)

Vedantha Krishna, Amogh; Flys, Olena; Reddy, Vijeth V.; Rosén, B. G.

2018-06-01

A major drawback of the optical microscope is its limitation to resolve finer details. Many microscopes have been developed to overcome the limitations set by the diffraction of visible light. The scanning electron microscope (SEM) is one such alternative: it uses electrons for imaging, which have much smaller wavelength than photons. As a result high magnification with superior image resolution can be achieved. However, SEM generates 2D images which provide limited data for surface measurements and analysis. Often many research areas require the knowledge of 3D structures as they contribute to a comprehensive understanding of microstructure by allowing effective measurements and qualitative visualization of the samples under study. For this reason, stereo photogrammetry technique is employed to convert SEM images into 3D measurable data. This paper aims to utilize a stereoscopic reconstruction technique as a reliable method for characterization of surface topography. Reconstructed results from SEM images are compared with coherence scanning interferometer (CSI) results obtained by measuring a roughness reference standard sample. This paper presents a method to select the most robust/consistent surface texture parameters that are insensitive to the uncertainties involved in the reconstruction technique itself. Results from the two-stereoscopic reconstruction algorithms are also documented in this paper.

Design of hydrophobic polyoxometalate hybrid assemblies beyond surfactant encapsulation.

PubMed

Song, Yu-Fei; McMillan, Nicola; Long, De-Liang; Thiel, Johannes; Ding, Yulong; Chen, Haisheng; Gadegaard, Nikolaj; Cronin, Leroy

2008-01-01

Grafting of C-6, C-16 and C-18 alkyl chains onto the hydrophilic Mn-Anderson clusters (compounds 2-4) has been achieved. Exchange of the tetrabutyl ammonium (TBA) with dimethyldioctadecyl ammonium (DMDOA) results in the formation of new polyoxometalate (POM) assemblies (compounds 5-6), in which the POM cores are covalently functionalized by hydrophilic alkyl-chains and enclosed by surfactant of DMDOABr. As a result, we have been able to design and synthesize POM-containing hydrophobic materials beyond surfactant encapsulation. In solid state, scanning electron and transmission electron microscopy (SEM and TEM) studies of the TBA salts of compounds 3 and 4 show highly ordered, uniform, reproducible assemblies with unique segmented rodlike morphology. SEM and TEM studies of the DMDOA salts of compounds 5 and 6 show that they form spherical and sea urchin 3D objects in different solvent systems. In solution, the physical properties of compound 5 and 6 (combination of surfactant-encapsulated cluster (SEC) and surface-grafted cluster (SGC)) show a liquid-to-gel phase transition in pure chloroform below 0 degrees C, which are much lower than other reported SECs. By utilizing light scattering measurements, the nanoparticle size for compounds 5 and 6 were measured at 5 degrees C and 30 degrees C, respectively. Other physical properties including differential scanning calorimetry have been reported.

Ultrasound-assisted facile synthesis of a new tantalum(V) metal-organic framework nanostructure: Design, characterization, systematic study, and CO2 adsorption performance

NASA Astrophysics Data System (ADS)

Sargazi, Ghasem; Afzali, Daryoush; Mostafavi, Ali; Ebrahimipour, S. Yousef

2017-06-01

This work presents a fast route for the preparation of a new Ta(V) metal-organic framework nanostructure with high surface area, significant porosity, and small size distribution. X-ray diffraction (XRD), scanning electron microscopy (SEM), Transition electron microscopy (TEM), energy dispersive spectrometer (EDS), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), CHNS/O elemental analyser, and Brunauer-Emmett-Teller (BET) surface area analysis were applied to characterize the synthesized product. Moreover, the influences of ultrasonic irradiation including temperature, time, and power on different features of the final products were systematically studied using 2k-1 factorial design experiments, and the response surface optimization was used for determining the best welding parameter combination. The results obtained from analyses of variances showed that ultrasonic parameters affected the size distribution, thermal behaviour, and surface area of Ta-MOF samples. Based on response surface methodology, Ta-MOF could be obtained with mean diameter of 55 nm, thermal stability of 228 °C, and high surface area of 2100 m2/g. The results revealed that the synthesized products could be utilized in various applications such as a novel candidate for CO2 adsorption.

The Application of Scanning Electron Microscopy with Energy-Dispersive X-Ray Spectroscopy (SEM-EDX) in Ancient Dental Calculus for the Reconstruction of Human Habits.

PubMed

Fialová, Dana; Skoupý, Radim; Drozdová, Eva; Paták, Aleš; Piňos, Jakub; Šín, Lukáš; Beňuš, Radoslav; Klíma, Bohuslav

2017-12-01

The great potential of scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) is in detection of unusual chemical elements included in ancient human dental calculus to verify hypotheses about life and burial habits of historic populations and individuals. Elemental spectra were performed from archeological samples of three chosen individuals from different time periods. The unusual presence of magnesium, aluminum, and silicon in the first sample could confirm the hypothesis of high degree of dental abrasion caused by particles from grinding stones in flour. In the second sample, presence of copper could confirm that bronze jewelery could lie near the buried body. The elemental composition of the third sample with the presence of lead and copper confirms the origin of individual to Napoleonic Wars because the damage to his teeth could be explained by the systematic utilization of the teeth for the opening of paper cartridges (a charge with a dose of gunpowder and a bullet), which were used during the 18th and the 19th century AD. All these results contribute to the reconstruction of life (first and third individual) and burial (second individual) habits of historic populations and individuals.

The Evaluation of Hydroxyapatite (HA) Coated and Uncoated Porous Tantalum for Biomedical Material Applications

NASA Astrophysics Data System (ADS)

Safuan, Nadia; Sukmana, Irza; Kadir, Mohammed Rafiq Abdul; Noviana, Deni

2014-04-01

Porous tantalum has been used as an orthopedic implant for bone defects as it has a good corrosion resistance and fatigue behaviour properties. However, there are some reports on the rejection of porous Ta after the implantation. Those clinical cases refer to the less bioactivity of metallic-based materials. This study aims to evaluate hydroxyapatite coated and uncoated porous Tantalum in order to improve the biocompatibility of porous tantalum implant and osseointegration. Porous tantalum was used as metallic-base substrate and hydroxyapatite coating has been done using plasma-spraying technique. Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FESEM) techniques were utilizes to investigate the coating characteristics while Confocal Raman Microscopy to investigate the interface and image. The effect of coating to the corrosion behaviour was assessed by employing potentiodynamic polarization tests in simulated body fluid at 37±1 °C. Based on SEM and FESEM results, the morphologies as well the weight element consists in the uncoated and hydroxyapatite coated porous tantalum were revealed. The results indicated that the decrease in corrosion current density for HA coated porous Ta compared to the uncoated porous Ta. This study concluded that by coating porous tantalum with HA supports to decrease the corrosion rate of pure porous.

Encapsulation of anticancer drug and magnetic particles in biodegradable polymer nanospheres

NASA Astrophysics Data System (ADS)

Koneracká, M.; Múčková, M.; Závišová, V.; Tomašovičová, N.; Kopčanský, P.; Timko, M.; Juríková, A.; Csach, K.; Kavečanský, V.; Lancz, G.

2008-05-01

In this study, we have prepared PLGA (poly-D,L-lactide-co-glycolide) nanospheres loaded with biocompatible magnetic fluid and anticancer drug taxol by a modified nanoprecipitation technique and investigated their magnetic properties. A magnetic fluid, MF-PEG, with a biocompatible layer of polyethylene glycol (PEG), was chosen as a magnetic carrier. The PLGA, whose copolymer ratio of D,L-lactide to glycolide is 85:15, was utilized as a capsulation material. Taxol, as an important anticancer drug, was chosen for its significant role against a wide range of tumours. The morphology and particle size distributions of the prepared nanospheres were investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and showed a spherical shape of prepared nanospheres with size 250 nm. Infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetry (TGA) analysis confirmed incorporation of magnetic particles and taxol into the PLGA polymer. The results showed good encapsulation with magnetite content 21.5 wt% and taxol 0.5 wt%. Magnetic properties of magnetic fluids and taxol within the PLGA polymer matrix were investigated by SQUID magnetometry from 4.2 to 300 K. The SQUID measurements showed superparamagnetism of prepared nanospheres with a blocking temperature of 160 K and saturation magnetization 1.4 mT.

Accurate virus quantitation using a Scanning Transmission Electron Microscopy (STEM) detector in a scanning electron microscope.

PubMed

Blancett, Candace D; Fetterer, David P; Koistinen, Keith A; Morazzani, Elaine M; Monninger, Mitchell K; Piper, Ashley E; Kuehl, Kathleen A; Kearney, Brian J; Norris, Sarah L; Rossi, Cynthia A; Glass, Pamela J; Sun, Mei G

2017-10-01

A method for accurate quantitation of virus particles has long been sought, but a perfect method still eludes the scientific community. Electron Microscopy (EM) quantitation is a valuable technique because it provides direct morphology information and counts of all viral particles, whether or not they are infectious. In the past, EM negative stain quantitation methods have been cited as inaccurate, non-reproducible, and with detection limits that were too high to be useful. To improve accuracy and reproducibility, we have developed a method termed Scanning Transmission Electron Microscopy - Virus Quantitation (STEM-VQ), which simplifies sample preparation and uses a high throughput STEM detector in a Scanning Electron Microscope (SEM) coupled with commercially available software. In this paper, we demonstrate STEM-VQ with an alphavirus stock preparation to present the method's accuracy and reproducibility, including a comparison of STEM-VQ to viral plaque assay and the ViroCyt Virus Counter. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Correlation of live-cell imaging with volume scanning electron microscopy.

PubMed

Lucas, Miriam S; Günthert, Maja; Bittermann, Anne Greet; de Marco, Alex; Wepf, Roger

2017-01-01

Live-cell imaging is one of the most widely applied methods in live science. Here we describe two setups for live-cell imaging, which can easily be combined with volume SEM for correlative studies. The first procedure applies cell culture dishes with a gridded glass support, which can be used for any light microscopy modality. The second approach is a flow-chamber setup based on Ibidi μ-slides. Both live-cell imaging strategies can be followed up with serial blockface- or focused ion beam-scanning electron microscopy. Two types of resin embedding after heavy metal staining and dehydration are presented making best use of the particular advantages of each imaging modality: classical en-bloc embedding and thin-layer plastification. The latter can be used only for focused ion beam-scanning electron microscopy, but is advantageous for studying cell-interactions with specific substrates, or when the substrate cannot be removed. En-bloc embedding has diverse applications and can be applied for both described volume scanning electron microscopy techniques. Finally, strategies for relocating the cell of interest are discussed for both embedding approaches and in respect to the applied light and scanning electron microscopy methods. Copyright © 2017 Elsevier Inc. All rights reserved.

Scanning electron microscope fractography in failure analysis of steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wouters, R.; Froyen, L.

1996-04-01

For many failure cases, macroscopic examination of the fracture surface permits discrimination of fatigue fractures from overload fractures. For clarifying fatigue fractures, the practical significance of microfractography is limited to an investigation of the crack initiation areas. Scanning electron microscopy is successfully used in tracing local material abnormalities that act as fatigue crack initiators. The task for the scanning electron microscope, however, is much more substantial in failure analysis of overload fractures, especially for steels. By revealing specific fractographic characteristics, complemented by information about the material and the loading conditions, scanning electron microscopy provides a strong indication of the probablemore » cause of failure. A complete dimple fracture is indicative of acceptable bulk material properties; overloading, by subdimensioning or excessive external loading, has to be verified. The presence of cleavage fracture makes the material properties questionable if external conditions causing embrittlement are absent. Intergranular brittle fracture requires verification of grain-boundary weakening conditions--a sensitized structure, whether or not combined with a local stress state or a specific environment. The role of scanning electron microscopy in failure analysis is illustrated by case histories of the aforementioned fracture types.« less

Method of achieving ultra-wideband true-time-delay beam steering for active electronically scanned arrays

DOEpatents

Loui, Hung; Brock, Billy C.

2016-10-25

The various embodiments presented herein relate to beam steering an array antenna by modifying intermediate frequency (IF) waveforms prior to conversion to RF signals. For each channel, a direct digital synthesis (DDS) component can be utilized to generate a waveform or modify amplitude, timing and phase of a waveform relative to another waveform, whereby the generation/modification can be performed prior to the IF input port of a mixer on each channel. A local oscillator (LO) signal can be utilized to commonly drive each of the mixers. After conversion at the RF output port of each of the mixers, each RF signal can be transmitted by a respective antenna element in the antenna array. Initiation of transmission of each RF signal can be performed simultaneously at each antenna. The process can be reversed during receive whereby timing, amplitude, and phase of the received can be modified digitally post ADC conversion.

Magnetic field controlled graphene oxide-based origami with enhanced surface area and mechanical properties.

PubMed

Park, Ok-Kyung; Tiwary, Chandra Sekhar; Yang, Yang; Bhowmick, Sanjit; Vinod, Soumya; Zhang, Qingbo; Colvin, Vicki L; Asif, S A Syed; Vajtai, Robert; Penev, Evgeni S; Yakobson, Boris I; Ajayan, Pulickel M

2017-06-01

One can utilize the folding of paper to build fascinating 3D origami architectures with extraordinary mechanical properties and surface area. Inspired by the same, the morphology of 2D graphene can be tuned by addition of magnetite (Fe 3 O 4 ) nanoparticles in the presence of a magnetic field. The innovative 3D architecture with enhanced mechanical properties also shows a high surface area (∼2500 m 2 g -1 ) which is utilized for oil absorption. Detailed microscopy and spectroscopy reveal rolling of graphene oxide (GO) sheets due to the magnetic field driven action of magnetite particles, which is further supported by molecular dynamics (MD) simulations. The macroscopic and local deformation resulting from in situ mechanical loading inside a scanning electron microscope reveals a change in the mechanical response due to a change internal morphology, which is further supported by MD simulation.

Effect of natural fibers on mechanical properties of green cement mortar

NASA Astrophysics Data System (ADS)

AL-Zubaidi, Aseel B.

2018-05-01

Natural fibers of banana, reed, palm and coconut were used to reinforce cement composite. Optical microscopy showed that the prepared fibers are different in size and morphology. Nearly equiaxed, ribbon-like and nearly cylindrical morphologies were observed. Each of the utilized natural fibers was incorporated in the cement matrix at 0, 0.25, 0.5, 0.75 and 1.0 wt% and cured for 28 days. The scanning electron micrographs for the 1.0 wt% -reinforced composite showed differences in porosity, grain size and shape. Each of the utilized fibers has different effect on the microstructure of the cement composite that depends on the fiber size and morphology. Water absorption, thermal conductivity, bending strength, hardness and compression strengths were measured for the reinforced cement composite. It is found that the final physical and mechanical properties of the set cement composite depend on the fiber content and fiber type through the differences in their sizes and morphologies.

Development and (evidence for) destruction of biofilm with Pseudomonas aeruginosa as architect

NASA Technical Reports Server (NTRS)

Uzcategui, Valerie N.; Donadeo, John J.; Lombardi, Daniel R.; Costello, Michael J.; Sauer, Richard L.

1991-01-01

Disinfection and maintenance of an acceptable level of asepsis in spacecraft potable water delivery systems is a formidable task. The major area of research for this project has been to monitor the formation and growth of biofilm, and biofilm attached microorganisms, on stainless steel surfaces (specifically coupons), and the use of ozone for the elimination of these species in a closed loop system. A number of different techniques have been utilized during the course of a typical run. Scraping and sonication of coupon surfaces with subsequent plating as well as epifluorescence microscopy have been utilized to enumerate biofilm protected Pseudomonas aeruginosa. In addition, scanning electron microscopy is the method of choice to examine the integrity of the biofilm. For ozone determinations, the indigo decolorization spectrophotometric method seems most reliable. Both high- and low-nutrient cultured P. aeruginosa organisms were the target species for the ozone disinfection experiments.

A novel process for comprehensive utilization of vanadium slag

NASA Astrophysics Data System (ADS)

Liu, Li-ying; Du, Tao; Tan, Wen-jun; Zhang, Xin-pu; Yang, Fan

2016-02-01

Traditional processes for treating vanadium slag generate a huge volume of solid residue and a large amount of harmful gas, which cause serious environmental problems. In this study, a new process for the comprehensive utilization of vanadium slag was proposed, wherein zeolite A and a V2O5/TiO2 system were synthesized. The structural properties of the as-synthesized zeolite A and the V2O5/TiO2 system were characterized using various experimental techniques, including X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and infrared spectroscopy. The results reveal that zeolite A and the V2O5/TiO2 system are successfully obtained with high purity. The results of gas adsorption measurements indicate that the prepared zeolite A exhibits high selectivity for CO2 over N2 and is a candidate material for CO2 capture from flue-gas streams.

Sensitivity to detect small coronary artery calcium lesions with varying slice thickness using electron beam tomography.

PubMed

Mao, Songshou; Child, Janis; Carson, Sivi; Liu, Steve C K; Oudiz, Ronald J; Budoff, Matthew J

2003-03-01

To estimate the sensitivity to find small coronary artery calcium lesions with use of different slice widths with electron beam tomography. Two studies were performed. Study 1 utilized double scanning of a stationary cork phantom with three different slice thickness (1.5, 3, and 6 mm). Fifty different calcific lesions (all <20 mm2 in area) fitted in 10 cork coronary arteries were utilized. The calcium foci area, peak value and score were measured and compared. In group 2, 30 patients underwent coronary artery calcium (CAC) screen studies. Each patient was scanned with both 3-mm and 6-mm scan widths in a same study time. Lesions with < 20 mm2 of area of CAC were measured on both 3-mm and 6-mm images. The mean and peak Hounsfield unit measure, and Agatston score were compared between both images. In the cork study, the sensitivity to detect small calcium foci were 96% (48/50), 82% (41/50), and 34% (17/50) in images with 1.5-, 3-, and 6-mm slice thickness, respectively. There is a smaller value in mass, and calcium volume in 6-mm images than 1.5-mm and 3-mm images ( P< 0.001). There was no significant difference between the true value and measured value from 1.5-mm and 3-mm images. In the human study, 18 (30%) of 60 CAC lesions with an area < 20 mm2 defined on 3 mm images were not visible on 6-mm images. Sensitivity of small lesions (P< 5 mm2) was 48% using 6-mm slices. There was a smaller value in CAC area, mean and peak Hounsfield units and score measured from 6-mm images, as compared with 3 mm slices ( P< 0.05). Thinner slice imaging has a higher sensitivity to detect small calcium focus. There was no significant change in score between 3 mm and 1.5 mm on the cork phantom study. However, the use of 6-mm slices should be discouraged, as this protocol both underestimates calcific mass and misses a significant number of calcific lesions in both a phantom and human study.

An audit of imaging test utilization for the management of lymphoma in an oncology hospital: implications for resource planning?

PubMed

Schwartz, A; Gospodarowicz, M K; Khalili, K; Pintilie, M; Goddard, S; Keller, A; Tsang, R W

2006-02-01

The purpose of this study was to assist with resource planning by examining the pattern of physician utilization of imaging procedures for lymphoma patients in a dedicated oncology hospital. The proportion of imaging tests ordered for routine follow up with no specific clinical indication was quantified, with specific attention to CT scans. A 3-month audit was performed. The reasons for ordering all imaging procedures (X-rays, CT scans, ultrasound, nuclear scan and MRI) were determined through a retrospective chart review. 411 lymphoma patients had 686 assessments (sets of imaging tests) and 981 procedures (individual imaging tests). Most procedures were CT scans (52%) and chest radiographs (30%). The most common reasons for ordering imaging were assessing response (23%), and investigating new symptoms (19%). Routine follow up constituted 21% of the assessments (142/686), and of these, 82% were chest radiographs (116/142), while 24% (34/142) were CT scans. With analysis restricted to CT scans (296 assessments in 248 patients), the most common reason for ordering CT scans were response evaluation (40%), and suspicion of recurrence and/or new symptom (23%). Follow-up CT scans done with no clinical indication comprised 8% (25/296) of all CT assessments. Staging CT scans were under-represented at 6% of all assessments. Imaging with CT scans for follow up of asymptomatic patients is infrequent. However, scans done for staging new lymphoma patients were unexpectedly low in frequency, due to scans done elsewhere prior to referral. This analysis uncovered utilization patterns, helped resource planning and provided data to reduce unnecessary imaging procedures.

Field Emission Auger Electron Spectroscopy with Scanning Auger Microscopy |

Science.gov Websites

0.5 at.% for elements from lithium to uranium. Depth Profiling Removes successive layers by using size (> ~25 nm). Imaging Obtains SEM micrographs with up to 20,000x magnification by using raster scanning with a highly focused electron beam ≥25 nm in diameter. Using the same raster scan, SAM can

Effects of Digitization and JPEG Compression on Land Cover Classification Using Astronaut-Acquired Orbital Photographs

NASA Technical Reports Server (NTRS)

Robinson, Julie A.; Webb, Edward L.; Evangelista, Arlene

2000-01-01

Studies that utilize astronaut-acquired orbital photographs for visual or digital classification require high-quality data to ensure accuracy. The majority of images available must be digitized from film and electronically transferred to scientific users. This study examined the effect of scanning spatial resolution (1200, 2400 pixels per inch [21.2 and 10.6 microns/pixel]), scanning density range option (Auto, Full) and compression ratio (non-lossy [TIFF], and lossy JPEG 10:1, 46:1, 83:1) on digital classification results of an orbital photograph from the NASA - Johnson Space Center archive. Qualitative results suggested that 1200 ppi was acceptable for visual interpretive uses for major land cover types. Moreover, Auto scanning density range was superior to Full density range. Quantitative assessment of the processing steps indicated that, while 2400 ppi scanning spatial resolution resulted in more classified polygons as well as a substantially greater proportion of polygons < 0.2 ha, overall agreement between 1200 ppi and 2400 ppi was quite high. JPEG compression up to approximately 46:1 also did not appear to have a major impact on quantitative classification characteristics. We conclude that both 1200 and 2400 ppi scanning resolutions are acceptable options for this level of land cover classification, as well as a compression ratio at or below approximately 46:1. Auto range density should always be used during scanning because it acquires more of the information from the film. The particular combination of scanning spatial resolution and compression level will require a case-by-case decision and will depend upon memory capabilities, analytical objectives and the spatial properties of the objects in the image.

Electronic structure of the La 1 + xBa 2 - xCu 3O 7 + δ system studied by photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Lindberg, P. A. P.; Shen, Z.-X.; Hwang, J.; Shih, C. K.; Lindau, I.; Spicer, W. E.; Mitzi, D. B.; Kapitulnik, A.

1989-01-01

Photoemission experiments utilizing synchrotron radiation have been carried out on the high temperature superconductor La 1.075Ba 1.925Cu 3O 7.0. The valence band spectra show similar spectral features as those of YBa 2Cu 3O 6.9, even though large differences in relative peak intensities are observed. Oxygen-related states are identified by scanning the photon energy through the O2 s → O2 p absorption edge. The stability of the sample surface, and changes in the valence band spectra after annealing in ultrahigh vacuum are also briefly discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tyagi, Mukta; Agrawal, V. V.; Chandran, Achu

A unique cholesterol oxidase (ChOx) liquid crystal (LC) biosensor, based on the disruption of orientation in LCs, is developed for cholesterol detection. A self-assembled monolayer (SAM) of Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP) and (3-Aminopropyl)trimethoxy-silane (APTMS) is prepared on a glass plate by adsorption. The enzyme (ChOx) is immobilized on SAM surface for 12 h before utilizing the film for biosensing purpose. LC based biosensing study is conducted on SAM/ChOx/LC (5CB) cells for cholesterol concentrations ranging from 10 mg/dl to 250 mg/dl. The sensing mechanism has been verified through polarizing optical microscopy, scanning electron microscopy, and spectrometric techniques.

Thermal analysis and microstructural characterization of Mg-Al-Zn system alloys

NASA Astrophysics Data System (ADS)

Król, M.; Tański, T.; Sitek, W.

2015-11-01

The influence of Zn amount and solidification rate on the characteristic temperature of the evaluation of magnesium dendrites during solidification at different cooling rates (0.6-2.5°C) were examined by thermal derivative analysis (TDA). The dendrite coherency point (DCP) is presented with a novel approach based on second derivative cooling curve. Solidification behavior was examined via one thermocouple thermal analysis method. Microstructural assessments were described by optical light microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. These studies showed that utilization of d2T/dt2 vs. the time curve methodology provides for analysis of the dendrite coherency point

Microwave assisted combustion synthesis of nanocrystalline CoFe2O4 for LPG sensing

NASA Astrophysics Data System (ADS)

Chaudhari, Prashant; Acharya, S. A.; Darunkar, S. S.; Gaikwad, V. M.

2015-08-01

A microwave-assisted citrate precursor method has been utilized for synthesis of nanocrystalline powders of CoFe2O4. The process takes only a few minutes to obtain as-synthesized CoFe2O4. Structural properties of the synthesized material were investigated by X-ray diffraction; scanning electron microscopy, Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy. The gas sensing properties of thick film of CoFe2O4 prepared by screen printing towards Liquid Petroleum Gas (LPG) revealed that CoFe2O4 thick films are sensitive and shows maximum sensitivity at 350°C for 2500 ppm of LPG.

SEM observation on microbial like structure in the ferromanganese crust from the western Pacific Magellan Seamount

NASA Astrophysics Data System (ADS)

Yang, K.; Park, H.; Baik, H.; Kim, J.; Park, K. R.; Yoon, J.; Kim, J. W.

2016-12-01

Understanding the biogeochemical process in the Fe-Mn crust layer is important to reconstruct the paleo-environment when the Fe-Mn crust layer forms. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Electron Energy Loss Spectroscopy (EELS), and Polymerase Chain Reaction (PCR) were utilized to determine the redox states of Fe/Mn and microbial diversity at each layer. Samples were dredged from the western Pacific Magellan Seamount (OSM11) that consists of five well-defined layers from the rim (L1) to the core (L5). Some microbial like structures of sheath-like with filaments (L1 - L3), capsule-shaped (L2), fossilized coccolith mounds with phosphatized globules (L4), and bean-shaped (L4) were detected in entire layers. The cross sectional observation of bean-shaped microbe like structures encrusted with Fe-vernadite (L3) by Scanning Transmission Electron Microscopy (STEM) and Focused Ion Beam (FIB) technique revealed 1-μm diameter cavity in the center and porous structures of encrusting Fe-vernadite in periphery. Moreover, the organic carbon in the center cavity compared with inorganic C (from carbonate) in periphery was differentiated by C-K edge EELS spectra, suggesting that the microbe used to occupy. Indeed, the PCR analysis indicated the presence of functional gene (cumA; 1056bp & coxC; 810bp) association with Mn & Fe oxidizer that promote the formation of the crust. The cloning and sequencing of DNA PCR fragments revealed the appearance of geobacter species in L3 (G. sulfurreducens and G. lovleyi). The DNA molecular biological analysis and SEM direct observations suggest the evidence of biotic process in the formation of Fe-Mn crust.

Refixation of Osteochondral Fractures by an Ultrasound-Activated Pin System - An Ovine In Vivo Examination Using CT and Scanning Electron Microscope.

PubMed

H, Neumann; A P, Schulz; S, Breer; A, Unger; B, Kienast

2015-01-01

Osteochondral injuries, if not treated appropriately, often lead to severe osteoarthritis of the affected joint. Without refixation of the osteochondral fragment, human cartilage only repairs these defects imperfectly. All existing refixation systems for chondral defects have disadvantages, for instance bad MRI quality in the postoperative follow-up or low anchoring forces. To address the problem of reduced stability in resorbable implants, ultrasound-activated pins were developed. By ultrasound-activated melting of the tip of these implants a higher anchoring is assumed. Aim of the study was to investigate, if ultrasound-activated pins can provide a secure refixation of osteochondral fractures comparing to conventional screw and conventional, resorbable pin osteosynthesis. CT scans and scanning electron microscopy should proovegood refixation results with no further tissue damage by the melting of the ultrasound-activated pins in comparison to conventional osteosynthesis. Femoral osteochondral fragments in sheep were refixated with ultrasound-activated pins (SonicPin™), Ethipins(®) and screws (Asnis™). The quality of the refixated fragments was examined after three month of full weight bearing by CT scans and scanning electron microscopy of the cartilage surface. The CT examination found almost no statistically significant difference in the quality of refixation between the three different implants used. Concerning the CT morphology, ultrasound-activated pins demonstrated at least the same quality in refixation of osteochondral fragments as conventional resorbable pins or screws. The scanning electron microscopy showed no major surface damage by the three implants, especially any postulated cartilage damage induced by the heat of the ultrasound-activated pin. The screws protruded above the cartilage surface, which may affect the opposingtibial surface. Using CT scans and scanning electron microscopy, the SonicPin™, the Ethipin(®) and screws were at least equivalent in refixation quality of osteochondral fragments.

Analytical and numerical analysis of imaging mechanism of dynamic scanning electron microscopy.

PubMed

Schröter, M-A; Holschneider, M; Sturm, H

2012-11-02

The direct observation of small oscillating structures with the help of a scanning electron beam is a new approach to study the vibrational dynamics of cantilevers and microelectromechanical systems. In the scanning electron microscope, the conventional signal of secondary electrons (SE, dc part) is separated from the signal response of the SE detector, which is correlated to the respective excitation frequency for vibration by means of a lock-in amplifier. The dynamic response is separated either into images of amplitude and phase shift or into real and imaginary parts. Spatial resolution is limited to the diameter of the electron beam. The sensitivity limit to vibrational motion is estimated to be sub-nanometer for high integration times. Due to complex imaging mechanisms, a theoretical model was developed for the interpretation of the obtained measurements, relating cantilever shapes to interaction processes consisting of incident electron beam, electron-lever interaction, emitted electrons and detector response. Conclusions drawn from this new model are compared with numerical results based on the Euler-Bernoulli equation.

The effect of grain size on aluminum anodes for Al-air batteries in alkaline electrolytes

NASA Astrophysics Data System (ADS)

Fan, Liang; Lu, Huimin

2015-06-01

Aluminum is an ideal material for metallic fuel cells. In this research, different grain sizes of aluminum anodes are prepared by equal channel angular pressing (ECAP) at room temperature. Microstructure of the anodes is examined by electron backscatter diffraction (EBSD) in scanning electron microscope (SEM). Hydrogen corrosion rates of the Al anodes in 4 mol L-1 NaOH are determined by hydrogen collection method. The electrochemical properties of the aluminum anodes are investigated in the same electrolyte using electrochemical impedance spectroscopy (EIS) and polarization curves. Battery performance is also tested by constant current discharge at different current densities. Results confirm that the electrochemical properties of the aluminum anodes are related to grain size. Finer grain size anode restrains hydrogen evolution, improves electrochemical activity and increases anodic utilization rate. The proposed method is shown to effectively improve the performance of Al-air batteries.

Ag(I)-bovine serum albumin hydrosol-mediated formation of Ag3PO4/reduced graphene oxide composites for visible-light degradation of Rhodamine B solution.

PubMed

Ma, Peiyan; Chen, Anliang; Wu, Yan; Fu, Zhengyi; Kong, Wei; Che, Liyuan; Ma, Ruifang

2014-03-01

A cost-effective Ag(I)-bovine serum albumin (BSA) supramolecular hydrosol strategy was utilized to assemble Ag3PO4 nanospheres onto reduced graphene oxide (rGO) sheets. The obtained composites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy and Fourier transform infrared spectroscopy. Compared with the pure Ag3PO4 crystals and Ag3PO4 particles prepared with Ag(I)-BSA hydrosol as precursor, the Ag3PO4/rGO composites obtained with different content of graphene oxide indicated improved visible-light-driven photocatalysis activity for the decomposition of Rhodamine B aqueous solution. The results pointed to the possibility of synthesizing graphene-based photocatalysts by metal ion-BSA hydrosol. Copyright © 2013 Elsevier Inc. All rights reserved.

Near-field spectroscopic investigation of dual-band heavy fermion metamaterials.

PubMed

Gilbert Corder, Stephanie N; Chen, Xinzhong; Zhang, Shaoqing; Hu, Fengrui; Zhang, Jiawei; Luan, Yilong; Logan, Jack A; Ciavatti, Thomas; Bechtel, Hans A; Martin, Michael C; Aronson, Meigan; Suzuki, Hiroyuki S; Kimura, Shin-Ichi; Iizuka, Takuya; Fei, Zhe; Imura, Keiichiro; Sato, Noriaki K; Tao, Tiger H; Liu, Mengkun

2017-12-22

Broadband tunability is a central theme in contemporary nanophotonics and metamaterials research. Combining metamaterials with phase change media offers a promising approach to achieve such tunability, which requires a comprehensive investigation of the electromagnetic responses of novel materials at subwavelength scales. In this work, we demonstrate an innovative way to tailor band-selective electromagnetic responses at the surface of a heavy fermion compound, samarium sulfide (SmS). By utilizing the intrinsic, pressure sensitive, and multi-band electron responses of SmS, we create a proof-of-principle heavy fermion metamaterial, which is fabricated and characterized using scanning near-field microscopes with <50 nm spatial resolution. The optical responses at the infrared and visible frequency ranges can be selectively and separately tuned via modifying the occupation of the 4f and 5d band electrons. The unique pressure, doping, and temperature tunability demonstrated represents a paradigm shift for nanoscale metamaterial and metasurface design.

γ' Precipitation Study of a Co-Ni-Based Alloy

NASA Astrophysics Data System (ADS)

Locq, D.; Martin, M.; Ramusat, C.; Fossard, F.; Perrut, M.

2018-05-01

A Co-Ni-based alloy strengthened by γ'-(L12) precipitates was utilized to investigate the precipitation evolution after various cooling rates and several aging conditions. In this study, the precipitate size and volume fraction have been studied via scanning electron microscopy and transmission electron microscopy. The influence of the precipitation evolution was measured via microhardness tests. The cooling rate study shows a more sluggish γ' precipitation reaction compared to that observed in a Ni-based superalloy. Following a rapid cooling rate, the application of appropriate double aging treatments allows for the increase of the γ' volume fraction as well as the control of the size and distribution of the precipitates. The highest hardness values reach those measured on supersolvus cast and wrought Ni-based superalloys. The observed γ' precipitation behavior should have implications for the production, the heat treatment, the welding, or the additive manufacturing of this new class of high-temperature materials.

Effects of Nb Modification and Cooling Rate on the Microstructure in an Ultrahigh Carbon Steel

NASA Astrophysics Data System (ADS)

Hecht, Matthew D.; Webler, Bryan A.; Picard, Yoosuf N.

2018-04-01

In this study, two different melting methods were used to investigate effects of Nb modification on microstructure in ultrahigh carbon steel (UHCS). Nb-free and Nb-modified UHCS samples were produced by melting and resolidifying an industrially produced base UHCS with and without addition of Nb powder. Microstructure was characterized using scanning electron microscopy, X-ray diffraction, and electron dispersive spectroscopy. Equilibrium computations of phase fractions and compositions were utilized to help describe microstructural changes caused by the Nb additions. Nb combined with C to form NbC structures before and during austenite solidification, reducing the effective amount of carbon available for the other phases. Cementite network spacing in the Nb-free samples was controlled by the cooling rate during solidification (faster cooling led to a more refined network). Network spacing in the Nb-modified UHCS could be enlarged by NbC structures that formed cooperatively with austenite.

High performance organic transistor active-matrix driver developed on paper substrate

NASA Astrophysics Data System (ADS)

Peng, Boyu; Ren, Xiaochen; Wang, Zongrong; Wang, Xinyu; Roberts, Robert C.; Chan, Paddy K. L.

2014-09-01

The fabrication of electronic circuits on unconventional substrates largely broadens their application areas. For example, green electronics achieved through utilization of biodegradable or recyclable substrates, can mitigate the solid waste problems that arise at the end of their lifespan. Here, we combine screen-printing, high precision laser drilling and thermal evaporation, to fabricate organic field effect transistor (OFET) active-matrix (AM) arrays onto standard printer paper. The devices show a mobility and on/off ratio as high as 0.56 cm2V-1s-1 and 109 respectively. Small electrode overlap gives rise to a cut-off frequency of 39 kHz, which supports that our AM array is suitable for novel practical applications. We demonstrate an 8 × 8 AM light emitting diode (LED) driver with programmable scanning and information display functions. The AM array structure has excellent potential for scaling up.

Effects of charge inhomogeneities on elementary excitations in La 2-xSr xCuO₄

DOE PAGES

Park, S. R.; Hamann, A.; Pintschovius, L.; ...

2011-12-12

Purely local experimental probes of many copper oxide superconductors show that their electronic states are inhomogeneous in real space. For example, scanning tunneling spectroscopic imaging shows strong variations in real space, and according to nuclear quadrupole resonance (NQR) studies, the charge distribution in the bulk varies on the nanoscale. However, the analysis of the experimental results utilizing spatially averaged probes often ignores this fact. We have performed a detailed investigation of the doping dependence of the energy and linewidth of the zone-boundary Cu-O bond-stretching vibration in La 2-xSr xCuO₄ by inelastic neutron scattering. Both our results as well as previouslymore » reported angle-dependent momentum widths of the electronic spectral function detected by angle-resolved photoemission can be reproduced by including the same distribution of local environments extracted from the NQR analysis.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gilbert Corder, Stephanie N.; Chen, Xinzhong; Zhang, Shaoqing

Broadband tunability is a central theme in contemporary nanophotonics and metamaterials research. Combining metamaterials with phase change media offers a promising approach to achieve such tunability, which requires a comprehensive investigation of the electromagnetic responses of novel materials at subwavelength scales. In this work, we demonstrate an innovative way to tailor band-selective electromagnetic responses at the surface of a heavy fermion compound, samarium sulfide (SmS). By utilizing the intrinsic, pressure sensitive, and multi-band electron responses of SmS, we create a proof-of-principle heavy fermion metamaterial, which is fabricated and characterized using scanning near-field microscopes with < 50 nm spatial resolution. Themore » optical responses at the infrared and visible frequency ranges can be selectively and separately tuned via modifying the occupation of the 4f and 5d band electrons. The unique pressure, doping, and temperature tunability demonstrated represents a paradigm shift for nanoscale metamaterial and metasurface design.« less

Near-field spectroscopic investigation of dual-band heavy fermion metamaterials

DOE PAGES

Gilbert Corder, Stephanie N.; Chen, Xinzhong; Zhang, Shaoqing; ...

2017-12-22

Broadband tunability is a central theme in contemporary nanophotonics and metamaterials research. Combining metamaterials with phase change media offers a promising approach to achieve such tunability, which requires a comprehensive investigation of the electromagnetic responses of novel materials at subwavelength scales. In this work, we demonstrate an innovative way to tailor band-selective electromagnetic responses at the surface of a heavy fermion compound, samarium sulfide (SmS). By utilizing the intrinsic, pressure sensitive, and multi-band electron responses of SmS, we create a proof-of-principle heavy fermion metamaterial, which is fabricated and characterized using scanning near-field microscopes with < 50 nm spatial resolution. Themore » optical responses at the infrared and visible frequency ranges can be selectively and separately tuned via modifying the occupation of the 4f and 5d band electrons. The unique pressure, doping, and temperature tunability demonstrated represents a paradigm shift for nanoscale metamaterial and metasurface design.« less

Fabrication of Te@Au core-shell hybrids for efficient ethanol oxidation

NASA Astrophysics Data System (ADS)

Jin, Huile; Wang, Demeng; Zhao, Yuewu; Zhou, Huan; Wang, Shun; Wang, Jichang

2012-10-01

Using Au nanoparticles to catalyze the oxidation of alcohols has garnered increasing attention due to its potential application in direct alcohol fuel cells. In this research Te@Au core-shell hybrids were fabricated for the catalytic oxidation of ethanol, where the preparation procedure involved the initial production of Te crystals with different microstructures and the subsequent utilization of the Te crystal as a template and reducing agent for the production of Te@Au hybrids. The as-prepared core-shell hybrids were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction techniques. Electrochemical measurements illustrate that the hybrids have great electrocatalytic activity and stability toward ethanol oxidation in alkaline media. The enhanced electrocatalytic property may be attributed to the cooperative effects between the metal and semiconductor and the presence of a large number of active sites on the hybrids surface.

Toward Optical Sensors: Review and Applications

NASA Astrophysics Data System (ADS)

Sabri, Naseer; Aljunid, S. A.; Salim, M. S.; Ahmad, R. B.; Kamaruddin, R.

2013-04-01

Recent advances in fiber optics (FOs) and the numerous advantages of light over electronic systems have boosted the utility and demand for optical sensors in various military, industry and social fields. Environmental and atmospheric monitoring, earth and space sciences, industrial chemical processing and biotechnology, law enforcement, digital imaging, scanning, and printing are exemplars of them. The ubiquity of photonic technologies could drive down prices which reduced the cost of optical fibers and lasers. Fiber optic sensors (FOSs) offer a wide spectrum of advantages over traditional sensing systems, such as small size and longer lifetime. Immunity to electromagnetic interference, amenability to multiplexing, and high sensitivity make FOs the sensor technology of choice in several fields, including the healthcare and aerospace sectors. FOSs show reliable and rigid sensing tasks over conventional electrical and electronic sensors. This paper presents an executive review of optical fiber sensors and the most beneficial applications.

Tribological properties of graphene oxide and carbon spheres as lubricating additives

NASA Astrophysics Data System (ADS)

Song, Haojie; Wang, Zhiqiang; Yang, Jin

2016-10-01

The purpose of this paper was to investigate the tribological properties of carbon materials with various morphologies [i.e., graphene oxide (GO) and carbon spheres (CSs)] utilized as lubricating additives on a ball-plate tribotester. The morphology and spectroscopy characterization of GO and CSs were investigated by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrometry, and thermogravimetric analysis. Friction and wear properties of the sunflower seed oil filled with GO and CSs were investigated by using a MS-T3000 ball-on-disk apparatus. Results show that the sunflower seed oil containing 0.3 wt% GO nanosheets exhibited a substantial diminution in friction and wear compared with the 3.0 wt% CSs as sunflower seed oil additives. Formation of low-shear strength tribofilms containing GO and its self-lubricating behavior was the key factor in reduction of the friction and prevention from wear and deformation. In addition, friction mechanism of CSs was also discussed.

Joining of Silicon Carbide: Diffusion Bond Optimization and Characterization

NASA Technical Reports Server (NTRS)

Halbig, Michael C.; Singh, Mrityunjay

2008-01-01

Joining and integration methods are critically needed as enabling technologies for the full utilization of advanced ceramic components in aerospace and aeronautics applications. One such application is a lean direct injector for a turbine engine to achieve low NOx emissions. In the application, several SiC substrates with different hole patterns to form fuel and combustion air channels are bonded to form the injector. Diffusion bonding is a joining approach that offers uniform bonds with high temperature capability, chemical stability, and high strength. Diffusion bonding was investigated with the aid of titanium foils and coatings as the interlayer between SiC substrates to aid bonding. The influence of such variables as interlayer type, interlayer thickness, substrate finish, and processing time were investigated. Optical microscopy, scanning electron microscopy, and electron microprobe analysis were used to characterize the bonds and to identify the reaction formed phases.

Joining of Silicon Carbide Through the Diffusion Bonding Approach

NASA Technical Reports Server (NTRS)

Halbig, Michael .; Singh, Mrityunjay

2009-01-01

In order for ceramics to be fully utilized as components for high-temperature and structural applications, joining and integration methods are needed. Such methods will allow for the fabrication the complex shapes and also allow for insertion of the ceramic component into a system that may have different adjacent materials. Monolithic silicon carbide (SiC) is a ceramic material of focus due to its high temperature strength and stability. Titanium foils were used as an interlayer to form diffusion bonds between chemical vapor deposited (CVD) SiC ceramics with the aid of hot pressing. The influence of such variables as interlayer thickness and processing time were investigated to see which conditions contributed to bonds that were well adhered and crack free. Optical microscopy, scanning electron microscopy, and electron microprobe analysis were used to characterize the bonds and to identify the reaction formed phases.

XAP, a program for deconvolution and analysis of complex X-ray spectra

USGS Publications Warehouse

Quick, James E.; Haleby, Abdul Malik

1989-01-01

The X-ray analysis program (XAP) is a spectral-deconvolution program written in BASIC and specifically designed to analyze complex spectra produced by energy-dispersive X-ray analytical systems (EDS). XAP compensates for spectrometer drift, utilizes digital filtering to remove background from spectra, and solves for element abundances by least-squares, multiple-regression analysis. Rather than base analyses on only a few channels, broad spectral regions of a sample are reconstructed from standard reference spectra. The effects of this approach are (1) elimination of tedious spectrometer adjustments, (2) removal of background independent of sample composition, and (3) automatic correction for peak overlaps. Although the program was written specifically to operate a KEVEX 7000 X-ray fluorescence analytical system, it could be adapted (with minor modifications) to analyze spectra produced by scanning electron microscopes, electron microprobes, and probes, and X-ray defractometer patterns obtained from whole-rock powders.

Effects of Nb Modification and Cooling Rate on the Microstructure in an Ultrahigh Carbon Steel

NASA Astrophysics Data System (ADS)

Hecht, Matthew D.; Webler, Bryan A.; Picard, Yoosuf N.

2018-06-01

In this study, two different melting methods were used to investigate effects of Nb modification on microstructure in ultrahigh carbon steel (UHCS). Nb-free and Nb-modified UHCS samples were produced by melting and resolidifying an industrially produced base UHCS with and without addition of Nb powder. Microstructure was characterized using scanning electron microscopy, X-ray diffraction, and electron dispersive spectroscopy. Equilibrium computations of phase fractions and compositions were utilized to help describe microstructural changes caused by the Nb additions. Nb combined with C to form NbC structures before and during austenite solidification, reducing the effective amount of carbon available for the other phases. Cementite network spacing in the Nb-free samples was controlled by the cooling rate during solidification (faster cooling led to a more refined network). Network spacing in the Nb-modified UHCS could be enlarged by NbC structures that formed cooperatively with austenite.

Structural “ δ Doping” to Control Local Magnetization in Isovalent Oxide Heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moon, E. J.; He, Q.; Ghosh, S.

Modulation and δ-doping strategies, in which atomically thin layers of charged dopants are precisely deposited within a heterostructure, have played enabling roles in the discovery of new physical behavior in electronic materials. Here in this paper, we demonstrate a purely structural “δ-doping” strategy in complex oxide heterostructures, in which atomically thin manganite layers are inserted into an isovalent manganite host, thereby modifying the local rotations of corner-connected MnO 6 octahedra. Combining scanning transmission electron microscopy, polarized neutron reflectometry, and density functional theory, we reveal how local magnetic exchange interactions are enhanced within the spatially confined regions of suppressed octahedral rotations.more » Finally, the combined experimental and theoretical results illustrate the potential to utilize noncharge-based approaches to “doping” in order to enhance or suppress functional properties within spatially confined regions of oxide heterostructures.« less

High performance organic transistor active-matrix driver developed on paper substrate

PubMed Central

Peng, Boyu; Ren, Xiaochen; Wang, Zongrong; Wang, Xinyu; Roberts, Robert C.; Chan, Paddy K. L.

2014-01-01

The fabrication of electronic circuits on unconventional substrates largely broadens their application areas. For example, green electronics achieved through utilization of biodegradable or recyclable substrates, can mitigate the solid waste problems that arise at the end of their lifespan. Here, we combine screen-printing, high precision laser drilling and thermal evaporation, to fabricate organic field effect transistor (OFET) active-matrix (AM) arrays onto standard printer paper. The devices show a mobility and on/off ratio as high as 0.56 cm2V−1s−1 and 109 respectively. Small electrode overlap gives rise to a cut-off frequency of 39 kHz, which supports that our AM array is suitable for novel practical applications. We demonstrate an 8 × 8 AM light emitting diode (LED) driver with programmable scanning and information display functions. The AM array structure has excellent potential for scaling up. PMID:25234244

Structural “ δ Doping” to Control Local Magnetization in Isovalent Oxide Heterostructures

DOE PAGES

Moon, E. J.; He, Q.; Ghosh, S.; ...

2017-11-08

Modulation and δ-doping strategies, in which atomically thin layers of charged dopants are precisely deposited within a heterostructure, have played enabling roles in the discovery of new physical behavior in electronic materials. Here in this paper, we demonstrate a purely structural “δ-doping” strategy in complex oxide heterostructures, in which atomically thin manganite layers are inserted into an isovalent manganite host, thereby modifying the local rotations of corner-connected MnO 6 octahedra. Combining scanning transmission electron microscopy, polarized neutron reflectometry, and density functional theory, we reveal how local magnetic exchange interactions are enhanced within the spatially confined regions of suppressed octahedral rotations.more » Finally, the combined experimental and theoretical results illustrate the potential to utilize noncharge-based approaches to “doping” in order to enhance or suppress functional properties within spatially confined regions of oxide heterostructures.« less

Publications - GMC 58 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 58 Publication Details Title: X-ray diffraction and scanning electron microscopy mineral , Michael, and Core Laboratories, 1985, X-ray diffraction and scanning electron microscopy mineral analyses

Scanning electron microscope fine tuning using four-bar piezoelectric actuated mechanism

NASA Astrophysics Data System (ADS)

Hatamleh, Khaled S.; Khasawneh, Qais A.; Al-Ghasem, Adnan; Jaradat, Mohammad A.; Sawaqed, Laith; Al-Shabi, Mohammad

2018-01-01

Scanning Electron Microscopes are extensively used for accurate micro/nano images exploring. Several strategies have been proposed to fine tune those microscopes in the past few years. This work presents a new fine tuning strategy of a scanning electron microscope sample table using four bar piezoelectric actuated mechanisms. The introduced paper presents an algorithm to find all possible inverse kinematics solutions of the proposed mechanism. In addition, another algorithm is presented to search for the optimal inverse kinematic solution. Both algorithms are used simultaneously by means of a simulation study to fine tune a scanning electron microscope sample table through a pre-specified circular or linear path of motion. Results of the study shows that, proposed algorithms were able to minimize the power required to drive the piezoelectric actuated mechanism by a ratio of 97.5% for all simulated paths of motion when compared to general non-optimized solution.

STEM VQ Method, Using Scanning Transmission Electron Microscopy (STEM) for Accurate Virus Quantification

DTIC Science & Technology

2017-02-02

Corresponding Author Abstract Accurate virus quantification is sought, but a perfect method still eludes the scientific community. Electron...unlimited. UNCLASSIFIED 2 provides morphology data and counts all viral particles, including partial or noninfectious particles; however, EM methods ...consistent, reproducible virus quantification method called Scanning Transmission Electron Microscopy – Virus Quantification (STEM-VQ) which simplifies

Direct observation of iron-induced conformational changes of mitochondrial DNA by high-resolution field-emission in-lens scanning electron microscopy.

PubMed Central

Yaffee, M; Walter, P; Richter, C; Müller, M

1996-01-01

When respiring rat liver mitochondria are incubated in the presence of Fe(III) gluconate, their DNA (mtDNA) relaxes from the supercoiled to the open circular form dependent on the iron dose. Anaerobiosis or antioxidants fail to completely inhibit the unwinding. High-resolution field-emission in-lens scanning electron microscopy imaging, in concert with backscattered electron detection, pinpoints nanometer-range iron colloids bound to mtDNA isolated from iron-exposed mitochondria. High-resolution field-emission in-lens scanning electron microscopy with backscattered electron detection imaging permits simultaneous detailed visual analysis of DNA topology, iron dose-dependent mtDNA unwinding, and assessment of iron colloid formation on mtDNA strands. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8643576

Sub-nanometre resolution imaging of polymer-fullerene photovoltaic blends using energy-filtered scanning electron microscopy.

PubMed

Masters, Robert C; Pearson, Andrew J; Glen, Tom S; Sasam, Fabian-Cyril; Li, Letian; Dapor, Maurizio; Donald, Athene M; Lidzey, David G; Rodenburg, Cornelia

2015-04-24

The resolution capability of the scanning electron microscope has increased immensely in recent years, and is now within the sub-nanometre range, at least for inorganic materials. An equivalent advance has not yet been achieved for imaging the morphologies of nanostructured organic materials, such as organic photovoltaic blends. Here we show that energy-selective secondary electron detection can be used to obtain high-contrast, material-specific images of an organic photovoltaic blend. We also find that we can differentiate mixed phases from pure material phases in our data. The lateral resolution demonstrated is twice that previously reported from secondary electron imaging. Our results suggest that our energy-filtered scanning electron microscopy approach will be able to make major inroads into the understanding of complex, nano-structured organic materials.

Scanning measurement of Seebeck coefficient of a heated sample

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snyder, G. Jeffrey; Iwanaga, Shiho

2016-04-19

A novel scanning Seebeck coefficient measurement technique is disclosed utilizing a cold scanning thermocouple probe tip on heated bulk and thin film samples. The system measures variations in the Seebeck coefficient within the samples. The apparatus may be used for two dimensional mapping of the Seebeck coefficient on the bulk and thin film samples. This technique can be utilized for detection of defective regions, as well as phase separations in the sub-mm range of various thermoelectric materials.

External morphogenesis of the tardigrade Hypsibius dujardini as revealed by scanning electron microscopy.

PubMed

Gross, Vladimir; Minich, Irene; Mayer, Georg

2017-04-01

Tardigrada, commonly called water bears, is a taxon of microscopic panarthropods with five-segmented bodies and four pairs of walking legs. Although tardigrades have been known to science for several centuries, questions remain regarding many aspects of their biology, such as embryogenesis. Herein, we used scanning electron microscopy to document the external changes that occur during embryonic development in the tardigrade Hypsibius dujardini (Eutardigrada, Parachela, Hypsibiidae). Our results show an accelerated development of external features, with approximately 30 hrs separating the point at which external structures first become recognizable and a fully formed embryo. All segments appear to arise simultaneously between ∼20 and 25 hrs of development, and no differences in the degree of development could be detected between the limb buds at any stage. Claws emerge shortly after the limb buds and are morphologically similar to those of adults. The origin of the claws is concurrent with that of the sclerotized parts of the mouth, suggesting that all cuticular structures arise simultaneously at ∼30 hrs. The mouth arises as an invagination in the terminal region of the head at ∼25 hrs, closes later in development, and opens again shortly before hatching. The anlagen of the peribuccal lobes arise as one dorsal and one ventral row, each consisting of three lobes, and later form a ring in the late embryo, whereas there is no indication of a labrum anlage at any point during development. Furthermore, we describe limited postembryonic development in the form of cuticular pores that are absent in juveniles but present in adults. This study represents the first scanning electron micrographs of tardigrade embryos, demonstrating the utility of this technique for studying embryogenesis in tardigrades. This work further adds an external morphological perspective to the developmental data already available for H. dujardini, facilitating future comparisons to related panarthropod taxa. J. Morphol. 278:563-573, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Implementation of a CT Scan Practice Guideline for Pediatric Trauma Patients Reduces Unnecessary Scans Without Impacting Outcomes.

PubMed

McGrew, Patrick R; Chestovich, Paul J; Fisher, Jay D; Kuhls, Deborah A; Fraser, Douglas R; Patel, Purvi P; Katona, Chad W; Saquib, Syed; Fildes, John J

2018-05-04

Computed Tomography (CT) scans are useful in the evaluation of trauma patients, but are costly and pose risks from ionizing radiation in children. Recent literature has demonstrated the utility of CT scan guidelines in the management of pediatric trauma. This study objective is to review our treatment of pediatric blunt trauma patients and evaluate CT utilization before and after CT-guideline implementation. Our Pediatric Level 2 Trauma Center (TC) implemented a CT scan practice guideline for pediatric trauma patients in March 2014. The guideline recommended for or against CT of the head and abdomen/pelvis utilizing published criteria from the Pediatric Emergency Care and Research Network (PECARN). There was no chest CT guideline. We reviewed all pediatric trauma patients for CT scans obtained during initial evaluation before and after guideline implementation, excluding inpatient scans. The Trauma Registry Database was queried to include all pediatric (age<15) trauma patients seen in our TC from 2010-2016, excluding penetrating mechanism and deaths in the TC. Scans were considered positive if organ injury was detected. Primary outcome was the proportion of patients undergoing CT and percent positive CTs. Secondary outcomes were hospital length of stay (LOS), readmissions, and mortality. Categorical and continuous variables were analyzed with Chi-square and Wilcoxon rank-sum tests, respectively. P<0.05 was considered significant. We identified 1934 patients: 1106 pre- and 828 post-guideline. Absolute reductions in head, chest, and abdomen/pelvis CT scans were 17.7%, 11.5%, and 18.8% respectively (p<0.001). Percent positive head CTs were equivalent, but percent positive chest and abdomen CT increased after implementation. Secondary outcomes were unchanged. Implementation of a pediatric CT guideline significantly decreases CT utilization, reducing the radiation exposure without a difference in outcome. Trauma centers treating pediatric patients should adopt similar guidelines to decrease unnecessary CT scans in children. Level IV, Therapeutic Study.

Qualitative and quantitative interpretation of SEM image using digital image processing.

PubMed

Saladra, Dawid; Kopernik, Magdalena

2016-10-01

The aim of the this study is improvement of qualitative and quantitative analysis of scanning electron microscope micrographs by development of computer program, which enables automatic crack analysis of scanning electron microscopy (SEM) micrographs. Micromechanical tests of pneumatic ventricular assist devices result in a large number of micrographs. Therefore, the analysis must be automatic. Tests for athrombogenic titanium nitride/gold coatings deposited on polymeric substrates (Bionate II) are performed. These tests include microshear, microtension and fatigue analysis. Anisotropic surface defects observed in the SEM micrographs require support for qualitative and quantitative interpretation. Improvement of qualitative analysis of scanning electron microscope images was achieved by a set of computational tools that includes binarization, simplified expanding, expanding, simple image statistic thresholding, the filters Laplacian 1, and Laplacian 2, Otsu and reverse binarization. Several modifications of the known image processing techniques and combinations of the selected image processing techniques were applied. The introduced quantitative analysis of digital scanning electron microscope images enables computation of stereological parameters such as area, crack angle, crack length, and total crack length per unit area. This study also compares the functionality of the developed computer program of digital image processing with existing applications. The described pre- and postprocessing may be helpful in scanning electron microscopy and transmission electron microscopy surface investigations. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

Using the scanning electron microscope on the production line to assure quality semiconductors

NASA Technical Reports Server (NTRS)

Adolphsen, J. W.; Anstead, R. J.

1972-01-01

The use of the scanning electron microscope to detect metallization defects introduced during batch processing of semiconductor devices is discussed. A method of determining metallization integrity was developed which culminates in a procurement specification using the scanning microscope on the production line as a quality control tool. Batch process control of the metallization operation is monitored early in the manufacturing cycle.

Scanning electron microscopy combined with image processing technique: Analysis of microstructure, texture and tenderness in Semitendinous and Gluteus Medius bovine muscles.

PubMed

Pieniazek, Facundo; Messina, Valeria

2016-11-01

In this study the effect of freeze drying on the microstructure, texture, and tenderness of Semitendinous and Gluteus Medius bovine muscles were analyzed applying Scanning Electron Microscopy combined with image analysis. Samples were analyzed by Scanning Electron Microscopy at different magnifications (250, 500, and 1,000×). Texture parameters were analyzed by Texture analyzer and by image analysis. Tenderness by Warner-Bratzler shear force. Significant differences (p < 0.05) were obtained for image and instrumental texture features. A linear trend with a linear correlation was applied for instrumental and image features. Image texture features calculated from Gray Level Co-occurrence Matrix (homogeneity, contrast, entropy, correlation and energy) at 1,000× in both muscles had high correlations with instrumental features (chewiness, hardness, cohesiveness, and springiness). Tenderness showed a positive correlation in both muscles with image features (energy and homogeneity). Combing Scanning Electron Microscopy with image analysis can be a useful tool to analyze quality parameters in meat.Summary SCANNING 38:727-734, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

Flat panel ferroelectric electron emission display system

DOEpatents

Sampayan, Stephen E.; Orvis, William J.; Caporaso, George J.; Wieskamp, Ted F.

1996-01-01

A device which can produce a bright, raster scanned or non-raster scanned image from a flat panel. Unlike many flat panel technologies, this device does not require ambient light or auxiliary illumination for viewing the image. Rather, this device relies on electrons emitted from a ferroelectric emitter impinging on a phosphor. This device takes advantage of a new electron emitter technology which emits electrons with significant kinetic energy and beam current density.

Three-dimensional electron microscopy simulation with the CASINO Monte Carlo software.

PubMed

Demers, Hendrix; Poirier-Demers, Nicolas; Couture, Alexandre Réal; Joly, Dany; Guilmain, Marc; de Jonge, Niels; Drouin, Dominique

2011-01-01

Monte Carlo softwares are widely used to understand the capabilities of electron microscopes. To study more realistic applications with complex samples, 3D Monte Carlo softwares are needed. In this article, the development of the 3D version of CASINO is presented. The software feature a graphical user interface, an efficient (in relation to simulation time and memory use) 3D simulation model, accurate physic models for electron microscopy applications, and it is available freely to the scientific community at this website: www.gel.usherbrooke.ca/casino/index.html. It can be used to model backscattered, secondary, and transmitted electron signals as well as absorbed energy. The software features like scan points and shot noise allow the simulation and study of realistic experimental conditions. This software has an improved energy range for scanning electron microscopy and scanning transmission electron microscopy applications. Copyright © 2011 Wiley Periodicals, Inc.

Three-Dimensional Electron Microscopy Simulation with the CASINO Monte Carlo Software

PubMed Central

Demers, Hendrix; Poirier-Demers, Nicolas; Couture, Alexandre Réal; Joly, Dany; Guilmain, Marc; de Jonge, Niels; Drouin, Dominique

2011-01-01

Monte Carlo softwares are widely used to understand the capabilities of electron microscopes. To study more realistic applications with complex samples, 3D Monte Carlo softwares are needed. In this paper, the development of the 3D version of CASINO is presented. The software feature a graphical user interface, an efficient (in relation to simulation time and memory use) 3D simulation model, accurate physic models for electron microscopy applications, and it is available freely to the scientific community at this website: www.gel.usherbrooke.ca/casino/index.html. It can be used to model backscattered, secondary, and transmitted electron signals as well as absorbed energy. The software features like scan points and shot noise allow the simulation and study of realistic experimental conditions. This software has an improved energy range for scanning electron microscopy and scanning transmission electron microscopy applications. PMID:21769885

The spatial coherence function in scanning transmission electron microscopy and spectroscopy.

PubMed

Nguyen, D T; Findlay, S D; Etheridge, J

2014-11-01

We investigate the implications of the form of the spatial coherence function, also referred to as the effective source distribution, for quantitative analysis in scanning transmission electron microscopy, and in particular for interpreting the spatial origin of imaging and spectroscopy signals. These questions are explored using three different source distribution models applied to a GaAs crystal case study. The shape of the effective source distribution was found to have a strong influence not only on the scanning transmission electron microscopy (STEM) image contrast, but also on the distribution of the scattered electron wavefield and hence on the spatial origin of the detected electron intensities. The implications this has for measuring structure, composition and bonding at atomic resolution via annular dark field, X-ray and electron energy loss STEM imaging are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

Experimental investigation on the electrical contact behavior of rolling contact connector.

PubMed

Chen, Junxing; Yang, Fei; Luo, Kaiyu; Zhu, Mingliang; Wu, Yi; Rong, Mingzhe

2015-12-01

Rolling contact connector (RCC) is a new technology utilized in high performance electric power transfer systems with one or more rotating interfaces, such as radars, satellites, wind generators, and medical computed tomography machines. Rolling contact components are used in the RCC instead of traditional sliding contacts to transfer electrical power and/or signal. Since the requirement of the power transmission is increasing in these years, the rolling electrical contact characteristics become more and more important for the long-life design of RCC. In this paper, a typical form of RCC is presented. A series of experimental work are carried out to investigate the rolling electrical contact characteristics during its lifetime. The influence of a variety of factors on the electrical contact degradation behavior of RCC is analyzed under both vacuum and air environment. Based on the surface morphology and elemental composition changes in the contact zone, which are assessed by field emission scanning electron microscope and confocal laser scanning microscope, the mechanism of rolling electrical contact degradation is discussed.

Evaluations of Silica Aerogel-Based Flexible Blanket as Passive Thermal Control Element for Spacecraft Applications

NASA Astrophysics Data System (ADS)

Hasan, Mohammed Adnan; Rashmi, S.; Esther, A. Carmel Mary; Bhavanisankar, Prudhivi Yashwantkumar; Sherikar, Baburao N.; Sridhara, N.; Dey, Arjun

2018-03-01

The feasibility of utilizing commercially available silica aerogel-based flexible composite blankets as passive thermal control element in applications such as extraterrestrial environments is investigated. Differential scanning calorimetry showed that aerogel blanket was thermally stable over - 150 to 126 °C. The outgassing behavior, e.g., total mass loss, collected volatile condensable materials, water vapor regained and recovered mass loss, was within acceptable range recommended for the space applications. ASTM tension and tear tests confirmed the material's mechanical integrity. The thermo-optical properties remained nearly unaltered in simulated space environmental tests such as relative humidity, thermal cycling and thermo-vacuum tests and confirmed the space worthiness of the aerogel. Aluminized Kapton stitched or anchored to the blanket could be used to control the optical transparency of the aerogel. These outcomes highlight the potential of commercial aerogel composite blankets as passive thermal control element in spacecraft. Structural and chemical characterization of the material was also done using scanning electron microscopy, Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy.

A simple route to develop transparent doxorubicin-loaded nanodiamonds/cellulose nanocomposite membranes as potential wound dressings.

PubMed

Luo, Xiaogang; Zhang, Hao; Cao, Zhenni; Cai, Ning; Xue, Yanan; Yu, Faquan

2016-06-05

The objective of this study is to develop transparent porous nanodiamonds/cellulose nanocomposite membranes with controlled release of doxorubicin for potential applications as wound dressings, which were fabricated by tape casting method from dispersing carboxylated nanodiamonds and dissolving cellulose homogeneously in 7 wt% NaOH/12 wt% urea aqueous solution. By adjusting the carboxylated nanodiamonds content, various nanocomposite membranes were obtained. The structure and properties of these membranes have been investigated by light transmittance measurements, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), tensile tests, water loss analyses, etc. The drug loading and release was investigated using doxorubicin hydrochloride as a model drug. In vitro cytotoxicity assay of the membranes was also studied. This work presented a proof-of-concept utility of these membranes for loading and release of bioactive compounds to be employed as a candidate for wound dressing. Copyright © 2016 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Junxing; Yang, Fei, E-mail: yfei2007@mail.xjtu.edu.cn; Luo, Kaiyu

Rolling contact connector (RCC) is a new technology utilized in high performance electric power transfer systems with one or more rotating interfaces, such as radars, satellites, wind generators, and medical computed tomography machines. Rolling contact components are used in the RCC instead of traditional sliding contacts to transfer electrical power and/or signal. Since the requirement of the power transmission is increasing in these years, the rolling electrical contact characteristics become more and more important for the long-life design of RCC. In this paper, a typical form of RCC is presented. A series of experimental work are carried out to investigatemore » the rolling electrical contact characteristics during its lifetime. The influence of a variety of factors on the electrical contact degradation behavior of RCC is analyzed under both vacuum and air environment. Based on the surface morphology and elemental composition changes in the contact zone, which are assessed by field emission scanning electron microscope and confocal laser scanning microscope, the mechanism of rolling electrical contact degradation is discussed.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henry, Michael David; Young, Travis R.; Griffin, Ben

Here, this work reports the utilization of a recently developed film, ScAlN, as a silicon etch mask offering significant improvements in high etch selectivity to silicon. Utilization of ScAlN as a fluorine chemistry based deep reactive ion etch mask demonstrated etch selectivity at 23 550:1, four times better than AlN, 11 times better than Al 2O 3, and 148 times better than silicon dioxide with significantly less resputtering at high bias voltage than either Al 2O 3 or AlN. Ellipsometry film thickness measurements show less than 0.3 nm/min mask erosion rates for ScAlN. Micromasking of resputtered Al for Al 2Omore » 3, AlN, and ScAlN etch masks is also reported here, utilizing cross-sectional scanning electron microscope and confocal microscope roughness measurements. With lower etch bias, the reduced etch rate can be optimized to achieve a trench bottom surface roughness that is comparable to SiO 2 etch masks. Etch mask selectivity enabled by ScAlN is likely to make significant improvements in microelectromechanical systems, wafer level packaging, and plasma dicing of silicon.« less

Fast and low-dose computed laminography using compressive sensing based technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abbas, Sajid, E-mail: scho@kaist.ac.kr; Park, Miran, E-mail: scho@kaist.ac.kr; Cho, Seungryong, E-mail: scho@kaist.ac.kr

2015-03-31

Computed laminography (CL) is well known for inspecting microstructures in the materials, weldments and soldering defects in high density packed components or multilayer printed circuit boards. The overload problem on x-ray tube and gross failure of the radio-sensitive electronics devices during a scan are among important issues in CL which needs to be addressed. The sparse-view CL can be one of the viable option to overcome such issues. In this work a numerical aluminum welding phantom was simulated to collect sparsely sampled projection data at only 40 views using a conventional CL scanning scheme i.e. oblique scan. A compressive-sensing inspiredmore » total-variation (TV) minimization algorithm was utilized to reconstruct the images. It is found that the images reconstructed using sparse view data are visually comparable with the images reconstructed using full scan data set i.e. at 360 views on regular interval. We have quantitatively confirmed that tiny structures such as copper and tungsten slags, and copper flakes in the reconstructed images from sparsely sampled data are comparable with the corresponding structure present in the fully sampled data case. A blurring effect can be seen near the edges of few pores at the bottom of the reconstructed images from sparsely sampled data, despite the overall image quality is reasonable for fast and low-dose NDT.« less

Symposium N: Materials and Devices for Thermal-to-Electric Energy Conversion

DTIC Science & Technology

2010-08-24

X - ray diffraction, transmission electron microscopy, scanning electron microscopy, and dynamic light scattering. Thermal conductivity measurements...SEM), X - ray diffraction (XRD) measurements as well as Raman spectroscopy. The results from these techniques indicate a clear modification...was examined by using scanning electron microscope (SEM; HITACHI S-4500 model) attached with an energy dispersive x - ray spectroscopy. The electrical

Electron tomography of HEK293T cells using scanning electron microscope-based scanning transmission electron microscopy.

PubMed

You, Yun-Wen; Chang, Hsun-Yun; Liao, Hua-Yang; Kao, Wei-Lun; Yen, Guo-Ji; Chang, Chi-Jen; Tsai, Meng-Hung; Shyue, Jing-Jong

2012-10-01

Based on a scanning electron microscope operated at 30 kV with a homemade specimen holder and a multiangle solid-state detector behind the sample, low-kV scanning transmission electron microscopy (STEM) is presented with subsequent electron tomography for three-dimensional (3D) volume structure. Because of the low acceleration voltage, the stronger electron-atom scattering leads to a stronger contrast in the resulting image than standard TEM, especially for light elements. Furthermore, the low-kV STEM yields less radiation damage to the specimen, hence the structure can be preserved. In this work, two-dimensional STEM images of a 1-μm-thick cell section with projection angles between ±50° were collected, and the 3D volume structure was reconstructed using the simultaneous iterative reconstructive technique algorithm with the TomoJ plugin for ImageJ, which are both public domain software. Furthermore, the cross-sectional structure was obtained with the Volume Viewer plugin in ImageJ. Although the tilting angle is constrained and limits the resulting structural resolution, slicing the reconstructed volume generated the depth profile of the thick specimen with sufficient resolution to examine cellular uptake of Au nanoparticles, and the final position of these nanoparticles inside the cell was imaged.

Anisotropic Shape Changes of Silica Nanoparticles Induced in Liquid with Scanning Transmission Electron Microscopy.

PubMed

Zečević, Jovana; Hermannsdörfer, Justus; Schuh, Tobias; de Jong, Krijn P; de Jonge, Niels

2017-01-01

Liquid-phase transmission electron microscopy (TEM) is used for in-situ imaging of nanoscale processes taking place in liquid, such as the evolution of nanoparticles during synthesis or structural changes of nanomaterials in liquid environment. Here, it is shown that the focused electron beam of scanning TEM (STEM) brings about the dissolution of silica nanoparticles in water by a gradual reduction of their sizes, and that silica redeposites at the sides of the nanoparticles in the scanning direction of the electron beam, such that elongated nanoparticles are formed. Nanoparticles with an elongation in a different direction are obtained simply by changing the scan direction. Material is expelled from the center of the nanoparticles at higher electron dose, leading to the formation of doughnut-shaped objects. Nanoparticles assembled in an aggregate gradually fuse, and the electron beam exposed section of the aggregate reduces in size and is elongated. Under TEM conditions with a stationary electron beam, the nanoparticles dissolve but do not elongate. The observed phenomena are important to consider when conducting liquid-phase STEM experiments on silica-based materials and may find future application for controlled anisotropic manipulation of the size and the shape of nanoparticles in liquid. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mangum, John S.; Chan, Lisa H.; Schmidt, Ute

Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In thismore » work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice.« less

Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs.

PubMed

Mangum, John S; Chan, Lisa H; Schmidt, Ute; Garten, Lauren M; Ginley, David S; Gorman, Brian P

2018-05-01

Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In this work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice. Copyright © 2018 Elsevier B.V. All rights reserved.

Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs

DOE PAGES

Mangum, John S.; Chan, Lisa H.; Schmidt, Ute; ...

2018-02-23

Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In thismore » work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice.« less

Strain mapping in TEM using precession electron diffraction

DOEpatents

Taheri, Mitra Lenore; Leff, Asher Calvin

2017-02-14

A sample material is scanned with a transmission electron microscope (TEM) over multiple steps having a predetermined size at a predetermined angle. Each scan at a predetermined step and angle is compared to a template, wherein the template is generated from parameters of the material and the scanning. The data is then analyzed using local mis-orientation mapping and/or Nye's tensor analysis to provide information about local strain states.

Sparse imaging for fast electron microscopy

NASA Astrophysics Data System (ADS)

Anderson, Hyrum S.; Ilic-Helms, Jovana; Rohrer, Brandon; Wheeler, Jason; Larson, Kurt

2013-02-01

Scanning electron microscopes (SEMs) are used in neuroscience and materials science to image centimeters of sample area at nanometer scales. Since imaging rates are in large part SNR-limited, large collections can lead to weeks of around-the-clock imaging time. To increase data collection speed, we propose and demonstrate on an operational SEM a fast method to sparsely sample and reconstruct smooth images. To accurately localize the electron probe position at fast scan rates, we model the dynamics of the scan coils, and use the model to rapidly and accurately visit a randomly selected subset of pixel locations. Images are reconstructed from the undersampled data by compressed sensing inversion using image smoothness as a prior. We report image fidelity as a function of acquisition speed by comparing traditional raster to sparse imaging modes. Our approach is equally applicable to other domains of nanometer microscopy in which the time to position a probe is a limiting factor (e.g., atomic force microscopy), or in which excessive electron doses might otherwise alter the sample being observed (e.g., scanning transmission electron microscopy).

A Boundary Scan Test Vehicle for Direct Chip Attach Testing

NASA Technical Reports Server (NTRS)

Parsons, Heather A.; DAgostino, Saverio; Arakaki, Genji

2000-01-01

To facilitate the new faster, better and cheaper spacecraft designs, smaller more mass efficient avionics and instruments are using higher density electronic packaging technologies such as direct chip attach (DCA). For space flight applications, these technologies need to have demonstrated reliability and reasonably well defined fabrication and assembly processes before they will be accepted as baseline designs in new missions. As electronics shrink in size, not only can repair be more difficult, but 49 probing" circuitry can be very risky and it becomes increasingly more difficult to identify the specific source of a problem. To test and monitor these new technologies, the Direct Chip Attach Task, under NASA's Electronic Parts and Packaging Program (NEPP), chose the test methodology of boundary scan testing. The boundary scan methodology was developed for interconnect integrity and functional testing at hard to access electrical nodes. With boundary scan testing, active devices are used and failures can be identified to the specific device and lead. This technology permits the incorporation of "built in test" into almost any circuit and thus gives detailed test access to the highly integrated electronic assemblies. This presentation will describe boundary scan, discuss the development of the boundary scan test vehicle for DCA and current plans for testing of direct chip attach configurations.

Sub-nanometre resolution imaging of polymer–fullerene photovoltaic blends using energy-filtered scanning electron microscopy

PubMed Central

Masters, Robert C.; Pearson, Andrew J.; Glen, Tom S.; Sasam, Fabian-Cyril; Li, Letian; Dapor, Maurizio; Donald, Athene M.; Lidzey, David G.; Rodenburg, Cornelia

2015-01-01

The resolution capability of the scanning electron microscope has increased immensely in recent years, and is now within the sub-nanometre range, at least for inorganic materials. An equivalent advance has not yet been achieved for imaging the morphologies of nanostructured organic materials, such as organic photovoltaic blends. Here we show that energy-selective secondary electron detection can be used to obtain high-contrast, material-specific images of an organic photovoltaic blend. We also find that we can differentiate mixed phases from pure material phases in our data. The lateral resolution demonstrated is twice that previously reported from secondary electron imaging. Our results suggest that our energy-filtered scanning electron microscopy approach will be able to make major inroads into the understanding of complex, nano-structured organic materials. PMID:25906738

Flat panel ferroelectric electron emission display system

DOEpatents

Sampayan, S.E.; Orvis, W.J.; Caporaso, G.J.; Wieskamp, T.F.

1996-04-16

A device is disclosed which can produce a bright, raster scanned or non-raster scanned image from a flat panel. Unlike many flat panel technologies, this device does not require ambient light or auxiliary illumination for viewing the image. Rather, this device relies on electrons emitted from a ferroelectric emitter impinging on a phosphor. This device takes advantage of a new electron emitter technology which emits electrons with significant kinetic energy and beam current density. 6 figs.

Manganese oxide octahedral molecular sieves: Synthesis, self-assembly, control over morphologies and tunnel structure

NASA Astrophysics Data System (ADS)

Yuan, Jikang

Direct architecture of complex nanostructures is desirable and still remains a challenge in areas of materials science. Due to their size-, shape-dependent electronic and optical properties, much effort has been made to control morphologies of transition metal oxide nanoparticles and to organize them into complicated 3D structures using templates. In particular, manganese oxides have attracted much attention because they have extensive applications in many chemical processes due to their porous structures, acidity, ionexchange, separation, catalysis, and energy storage in secondary batteries. Using organic templates such as trimethylamine (TMA), manganese oxides have been successfully organized into macroscopic rings and helices via sol-gel processes. However, the methods mentioned above all need further purification, so impurities will be avoided. Subsequent procedures are needed to obtain pure products. Thus facile and template-free methods are highly desired for synthesis of manganese oxide nanaoparticles with complex 3D structures. Manganese oxide octahedral molecular sieves (OMS) are a class of microporous transition metallic oxides with various kinds of tunnel structures that can be synthesized via controlling synthetic conditions such as temperature, concentration, pH, and cations. Manganese oxide molecular sieves are semiconducting mixed-valence catalysts that utilize electron transport to catalyze reactions such as selective oxidation of alcohols. OMS has distinct advantages over aluminosilicate molecular sieve materials for applications in catalysis due to the mixed valence character. The synthesis of manganese oxide OMS materials will be much more complicated than those of main group metallic oxides because of different coordination numbers and oxidation states. OMS-type materials with desirable morphologies formed under mild synthetic conditions are highly desirable. Herein, we report a template-free, low temperature preparation of porous cryptomelane-type manganese oxide (OMS-2) 3D nanostructures. The objectives of this research include exploration of new methods to oxidize Mn2+ in aqueous solution either under low-temperature reflux or hydrothermal conditions. Various oxidants were used with precisely controlled synthetic parameters such as temperature, concentrations of starting materials, pH, and kinds of templates. A variety of techniques including powder X-ray diffraction and transmission electron microscopy (TEM) scanning electron microscopy are used to investigate the structures of synthesized materials. Atomic force microscopy (AFM) and scanning electron microscopy are utilized to studying the morphology and topography. The surface areas of the materials is measured by the BET method. Inductively coupled argon plasma atomic emission spectrometer (ICP-AES) are utilized to investigate the chemical composition of the materials. Thermal-stability of the materials is investigated by thermal gravimetric analysis (TGA). The objectives of this research includes exploring new synthetic approach such as oxidation of Mn2+ in aqueous solution by selecting suitable oxidants so as to control redox potential, varying pH of reaction systems, and controlling tunnel structures using hard templates (cations) under hydrothermal conditions.

Tunneling rates in electron transport through double-barrier molecular junctions in a scanning tunneling microscope

PubMed Central

Nazin, G. V.; Wu, S. W.; Ho, W.

2005-01-01

The scanning tunneling microscope enables atomic-scale measurements of electron transport through individual molecules. Copper phthalocyanine and magnesium porphine molecules adsorbed on a thin oxide film grown on the NiAl(110) surface were probed. The single-molecule junctions contained two tunneling barriers, vacuum gap, and oxide film. Differential conductance spectroscopy shows that electron transport occurs via vibronic states of the molecules. The intensity of spectral peaks corresponding to the individual vibronic states depends on the relative electron tunneling rates through the two barriers of the junction, as found by varying the vacuum gap tunneling rate by changing the height of the scanning tunneling microscope tip above the molecule. A simple, sequential tunneling model explains the observed trends. PMID:15956189

Tunneling rates in electron transport through double-barrier molecular junctions in a scanning tunneling microscope.

PubMed

Nazin, G V; Wu, S W; Ho, W

2005-06-21

The scanning tunneling microscope enables atomic-scale measurements of electron transport through individual molecules. Copper phthalocyanine and magnesium porphine molecules adsorbed on a thin oxide film grown on the NiAl(110) surface were probed. The single-molecule junctions contained two tunneling barriers, vacuum gap, and oxide film. Differential conductance spectroscopy shows that electron transport occurs via vibronic states of the molecules. The intensity of spectral peaks corresponding to the individual vibronic states depends on the relative electron tunneling rates through the two barriers of the junction, as found by varying the vacuum gap tunneling rate by changing the height of the scanning tunneling microscope tip above the molecule. A simple, sequential tunneling model explains the observed trends.

Utilization of nuclear medicine scintigraphy in Taiwan, 1997-2009.

PubMed

Hung, Mao-Chin; Hsieh, Wanhua Annie; Chang, Peter Wushou; Hwang, Jeng-Jong

2011-12-01

To analyze the utilization of nuclear medicine scintigraphy in the Taiwanese population within the national health-care system between 1997 and 2009. Based on the Taiwan's National Health Insurance Research Database of 1997-2009, a retrospective population-based analysis was conducted. Descriptive statistics and regression analysis were employed to analyze the frequencies and longitudinal trends in the utilization of diagnostic nuclear medicine procedures during the period. In addition, correlation analysis was applied to determine the correlated factors in the utility of nuclear medicine scintigraphy. The annual total nuclear medicine scintigraphy was estimated to be 256,389 on average in 1997-2009 and 11.7 per 1,000 population over the period. The frequency had increased by 67% over the years, from 8.2 per 1,000 population in 1997 to 13.7 per 1,000 population in 2009. The most frequently performed procedures were whole-body bone scans (33.4% of total) and myocardial perfusion scans (29.4% of total), with 4,615 and 5,620 increments per year, respectively. Most patients were in the age group of 41-65 years old when taking examinations. In addition, male subjects were slightly more than female patients (51.5 vs. 48.5%). Furthermore, the frequencies of whole-body bone scans and PET scans were proportional to the incidences of cancers (correlation coefficients were 0.96 and 0.94, respectively). The utilization of nuclear medicine scintigraphy with the National Health Insurance system in Taiwan has been changed considerably in the past 13 years. Both whole-body bone scan and myocardial perfusion scan were performed most often with significantly increases. The trend of nuclear medicine scintigraphy may have potential impact on making health-care policy in Taiwan.

EVALUATION OF COMPUTER-CONTROLLED SCANNING ELECTRON MICROSCOPY APPLIED TO AN AMBIENT URBAN AEROSOL SAMPLE

EPA Science Inventory

Concerns about the environmental and public health effects of particulate matter (PM) have stimulated interest in analytical techniques capable of measuring the size and chemical composition of individual aerosol particles. Computer-controlled scanning electron microscopy (CCSE...

Scanning electron microscopy of dentition: methodology and ultrastructural morphology of tooth wear.

PubMed

Shkurkin, G V; Almquist, A J; Pfeihofer, A A; Stoddard, E L

1975-01-01

Scanning electron micrographs were taken of sets of human molars-those of paleo-Indians used in mastication of, ostensibly, a highly abrasive diet, and those of contemporary Americans. Different ultrastructural patterns of enamel wear were observed between the groups.

Scanning-electron-microscope used in real-time study of friction and wear

NASA Technical Reports Server (NTRS)

Brainard, W. A.; Buckley, D. H.

1975-01-01

Small friction and wear apparatus built directly into scanning-electron-microscope provides both dynamic observation and microscopic view of wear process. Friction and wear tests conducted using this system have indicated that considerable information can readily be gained.

Nanoscale-Barrier Formation Induced by Low-Dose Electron-Beam Exposure in Ultrathin MoS2 Transistors.

PubMed

Matsunaga, Masahiro; Higuchi, Ayaka; He, Guanchen; Yamada, Tetsushi; Krüger, Peter; Ochiai, Yuichi; Gong, Yongji; Vajtai, Robert; Ajayan, Pulickel M; Bird, Jonathan P; Aoki, Nobuyuki

2016-10-05

Utilizing an innovative combination of scanning-probe and spectroscopic techniques, supported by first-principles calculations, we demonstrate how electron-beam exposure of field-effect transistors, implemented from ultrathin molybdenum disulfide (MoS 2 ), may cause nanoscale structural modifications that in turn significantly modify the electrical operation of these devices. Quite surprisingly, these modifications are induced by even the relatively low electron doses used in conventional electron-beam lithography, which are found to induce compressive strain in the atomically thin MoS 2 . Likely arising from sulfur-vacancy formation in the exposed regions, the strain gives rise to a local widening of the MoS 2 bandgap, an idea that is supported both by our experiment and by the results of first-principles calculations. A nanoscale potential barrier develops at the boundary between exposed and unexposed regions and may cause extrinsic variations in the resulting electrical characteristics exhibited by the transistor. The widespread use of electron-beam lithography in nanofabrication implies that the presence of such strain must be carefully considered when seeking to harness the potential of atomically thin transistors. At the same time, this work also promises the possibility of exploiting the strain as a means to achieve "bandstructure engineering" in such devices.

Detection of magnetic circular dichroism in amorphous materials utilizing a single-crystalline overlayer

DOE PAGES

Lin, J.; Zhong, X. Y.; Song, C.; ...

2017-12-27

Physicists are fascinated with topological defects in solid-state materials, because by breaking the translational symmetry they offer emerging properties that are not present in their parental phases. For example, edge dislocations—the 2π phase-winding topological defects—in antiferromagnetic NiO crystals can exhibit ferromagnetic behaviors. Herein, we study how these defects could give rise to exotic topological orders when they interact with a high energy electron beam. To probe this interaction, we formed a coherent electron nanobeam in a scanning transmission electron microscope and recorded the far-field transmitted patterns as the beam steps through the edge dislocation core in [001] NiO. Surprisingly, wemore » found the amplitude patterns of the <020> Bragg disks evolve in a similar manner to the evolution of an annular solar eclipse. Using the ptychographic technique, we recovered the missing phase information in the diffraction plane and revealed the topological phase vortices in the diffracted beams. Through atomic topological defects, the wave function of electrons can be converted from plane wave to electron vortex. This approach provides a new perspective for boosting the collection efficiency of magnetic circular dichroism spectra with high spatial resolution and understanding the relationship between symmetry breaking and exotic property of individual topological defect at atomic level.« less

Detection of magnetic circular dichroism in amorphous materials utilizing a single-crystalline overlayer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, J.; Zhong, X. Y.; Song, C.

Physicists are fascinated with topological defects in solid-state materials, because by breaking the translational symmetry they offer emerging properties that are not present in their parental phases. For example, edge dislocations—the 2π phase-winding topological defects—in antiferromagnetic NiO crystals can exhibit ferromagnetic behaviors. Herein, we study how these defects could give rise to exotic topological orders when they interact with a high energy electron beam. To probe this interaction, we formed a coherent electron nanobeam in a scanning transmission electron microscope and recorded the far-field transmitted patterns as the beam steps through the edge dislocation core in [001] NiO. Surprisingly, wemore » found the amplitude patterns of the <020> Bragg disks evolve in a similar manner to the evolution of an annular solar eclipse. Using the ptychographic technique, we recovered the missing phase information in the diffraction plane and revealed the topological phase vortices in the diffracted beams. Through atomic topological defects, the wave function of electrons can be converted from plane wave to electron vortex. This approach provides a new perspective for boosting the collection efficiency of magnetic circular dichroism spectra with high spatial resolution and understanding the relationship between symmetry breaking and exotic property of individual topological defect at atomic level.« less

Beam distribution reconstruction simulation for electron beam probe

NASA Astrophysics Data System (ADS)

Feng, Yong-Chun; Mao, Rui-Shi; Li, Peng; Kang, Xin-Cai; Yin, Yan; Liu, Tong; You, Yao-Yao; Chen, Yu-Cong; Zhao, Tie-Cheng; Xu, Zhi-Guo; Wang, Yan-Yu; Yuan, You-Jin

2017-07-01

An electron beam probe (EBP) is a detector which makes use of a low-intensity and low-energy electron beam to measure the transverse profile, bunch shape, beam neutralization and beam wake field of an intense beam with small dimensions. While it can be applied to many aspects, we limit our analysis to beam distribution reconstruction. This kind of detector is almost non-interceptive for all of the beam and does not disturb the machine environment. In this paper, we present the theoretical aspects behind this technique for beam distribution measurement and some simulation results of the detector involved. First, a method to obtain a parallel electron beam is introduced and a simulation code is developed. An EBP as a profile monitor for dense beams is then simulated using the fast scan method for various target beam profiles, including KV distribution, waterbag distribution, parabolic distribution, Gaussian distribution and halo distribution. Profile reconstruction from the deflected electron beam trajectory is implemented and compared with the actual profile, and the expected agreement is achieved. Furthermore, as well as fast scan, a slow scan, i.e. step-by-step scan, is considered, which lowers the requirement for hardware, i.e. Radio Frequency deflector. We calculate the three-dimensional electric field of a Gaussian distribution and simulate the electron motion in this field. In addition, a fast scan along the target beam direction and slow scan across the beam are also presented, and can provide a measurement of longitudinal distribution as well as transverse profile simultaneously. As an example, simulation results for the China Accelerator Driven Sub-critical System (CADS) and High Intensity Heavy Ion Accelerator Facility (HIAF) are given. Finally, a potential system design for an EBP is described.

The birth and evolution of surface science: child of the union of science and technology.

PubMed

Duke, C B

2003-04-01

This article is an account of the birth and evolution of surface science as an interdisciplinary research area. Surface science emanated from the confluence of concepts and tools in physics and chemistry with technological innovations that made it possible to determine the structure and properties of surfaces and interfaces and the dynamics of chemical reactions at surfaces. The combination in the 1960s and 1970s of ultra-high-vacuum (i.e., P < 10(-7) Pascal or 10(-9) Torr) technology with the recognition that electrons in the energy range from 50 to 500 eV exhibited inelastic collision mean free paths of the order of a few angstroms fostered an explosion of activity. The results were a reformulation of the theory of electron solid scattering, the nearly universal use of electron spectroscopies for surface characterization, the rise of surface science as an independent interdisciplinary research area, and the emergence of the American Vacuum Society (AVS) as a major international scientific society. The rise of microelectronics in the 1970s and 1980s resulted in huge increases in computational power. These increases enabled more complex experiments and the utilization of density functional theory for the quantitative prediction of surface structure and dynamics. Development of scanning-probe microscopies in the 1990s led to atomic-resolution images of macroscopic surfaces and interfaces as well as videos of atoms moving about on surfaces during growth and diffusion. Scanning probes have since brought solid-liquid interfaces into the realm of atomic-level surface science, expanding its scope to more complex systems, including fragile biological materials and processes.

Antibacterial and antibiofilm properties of yttrium fluoride nanoparticles

PubMed Central

Lellouche, Jonathan; Friedman, Alexandra; Gedanken, Aharon; Banin, Ehud

2012-01-01

Antibiotic resistance has prompted the search for new agents that can inhibit bacterial growth. Moreover, colonization of abiotic surfaces by microorganisms and the formation of biofilms is a major cause of infections associated with medical implants, resulting in prolonged hospitalization periods and patient mortality. In this study we describe a water-based synthesis of yttrium fluoride (YF3) nanoparticles (NPs) using sonochemistry. The sonochemical irradiation of an aqueous solution of yttrium (III) acetate tetrahydrate [Y(Ac)3 · (H2O)4], containing acidic HF as the fluorine ion source, yielded nanocrystalline needle-shaped YF3 particles. The obtained NPs were characterized by scanning electron microscopy and X-ray elemental analysis. NP crystallinity was confirmed by electron and powder X-ray diffractions. YF3 NPs showed antibacterial properties against two common bacterial pathogens (Escherichia coli and Staphylococcus aureus) at a μg/mL range. We were also able to demonstrate that antimicrobial activity was dependent on NP size. In addition, catheters were surface modified with YF3 NPs using a one-step synthesis and coating process. The coating procedure yielded a homogeneous YF3 NP layer on the catheter, as analyzed by scanning electron microscopy and energy dispersive spectroscopy. These YF3 NP-modified catheters were investigated for their ability to restrict bacterial biofilm formation. The YF3 NP-coated catheters were able to significantly reduce bacterial colonization compared to the uncoated surface. Taken together, our results highlight the potential to further develop the concept of utilizing these metal fluoride NPs as novel antimicrobial and antibiofilm agents, taking advantage of their low solubility and providing extended protection. PMID:23152681

Low vacuum scanning electron microscopy for paraffin sections utilizing the differential stainability of cells and tissues with platinum blue.

PubMed

Inaga, Sumire; Hirashima, Sayuri; Tanaka, Keiichi; Katsumoto, Tetsuo; Kameie, Toshio; Nakane, Hironobu; Naguro, Tomonori

2009-07-01

The present study introduces a novel method for the direct observation of histological paraffin sections by low vacuum scanning electron microscopy (LVSEM) with platinum blue (Pt-blue) treatment. Pt-blue was applied not only as a backscattered electron (BSE) signal enhancer but also as a histologically specific stain. In this method, paraffin sections of the rat tongue prepared for conventional light microscopy (LM) were stained on glass slides with a Pt-blue staining solution (pH 9) and observed in a LVSEM using BSE detector. Under LVSEM, overviews of whole sections as well as three-dimensional detailed observations of individual cells and tissues could be easily made at magnifications from x40 to x10,000. Each kind of cell and tissue observed in the section could be clearly distinguished due to the different yields of BSE signals, which depended on the surface structures and different affinities to Pt-blue. Thus, we roughly classified cellular and tissue components into three groups according to the staining intensity of Pt-blue observed by LM and LVSEM: 1) a strongly stained (deep blue by LM and brightest by LVSEM) group which included epithelial tissue, endothelium and mast cells; 2) a moderately stained (light blue and bright) group which included muscular tissue and nervous tissue; 3) an unstained or weakly stained (colorless and dark) group which included elastic fibers and collagen fibers. We expect that this method will prove useful for the three-dimensional direct observation of histological paraffin sections of various tissues by LVSEM with higher resolutions than LM.

Hydrothermal preparation of ZnO-reduced graphene oxide hybrid with high performance in photocatalytic degradation

NASA Astrophysics Data System (ADS)

Zhou, Xun; Shi, Tiejun; Zhou, Haiou

2012-06-01

Hydrothermal method was utilized to prepare reduced graphene oxide (RGO) and fabricate ZnO-RGO hybrid (ZnO-RGO) with zinc nitrate hexahydrate and graphene oxide (GO) as raw materials under pH value of 11 adjusted by ammonia water. During the process of reduction of GO, hydrothermal condition with ammonia provided thermal and chemical factors to synthesize RGO. The retained functional groups on RGO planes played an important role in anchoring ZnO to RGO, which was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopy and photoluminescence spectra. The various mass ratios of zinc nitrate hexahydrate to GO used to prepare ZnO-RGO impacted significantly on the morphology of ZnO nanostructures such as nanoparticles and nanorods. And, the RGO sheets wrapped ZnO nanoparticles and nanorods very tightly. After the emission of photo electrons from ZnO, RGO in ZnO-RGO can effectively transfer the photo electrons to exhibit a high performance and reproducibility in photocatalytic degradation toward methylene blue (MB) absorbed on the surface of RGO through π-π conjugation.

Synthesis of LaVO4/TiO2 heterojunction nanotubes by sol-gel coupled with hydrothermal method for photocatalytic air purification.

PubMed

Zou, Xuejun; Li, Xinyong; Zhao, Qidong; Liu, Shaomin

2012-10-01

With the aim of improving the effective utilization of visible light, the LaVO(4)/TiO(2) heterojunction nanotubes were fabricated by sol-gel coupled with hydrothermal method. The photocatalytic ability was demonstrated through catalytic removal of gaseous toluene species. The nanotube samples were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), surface photovoltage (SPV), Raman spectra and N(2) adsorption-desorption measurements. The characterization results showed that the samples with high specific surface areas were of typical nanotubular morphology, which would lead to the high separation and transfer efficiency of photo induced electron-hole pairs. The as-prepared nanotubes exhibited high photocatalytic activity in decomposing toluene species under visible light irradiation with fine photochemical stability. The enhanced photocatalytic performance of LaVO(4)/TiO(2) nanotubes might be attributed to the matching band potentials, the interconnected heterojunction of LaVO(4) versus TiO(2), and the large specific surface areas of nanotubes. Copyright © 2012 Elsevier Inc. All rights reserved.

Hierarchically porous carbon with manganese oxides as highly efficient electrode for asymmetric supercapacitors.

PubMed

Chou, Tsu-Chin; Doong, Ruey-An; Hu, Chi-Chang; Zhang, Bingsen; Su, Dang Sheng

2014-03-01

A promising energy storage material, MnO2 /hierarchically porous carbon (HPC) nanocomposites, with exceptional electrochemical performance and ultrahigh energy density was developed for asymmetric supercapacitor applications. The microstructures of MnO2 /HPC nanocomposites were characterized by transmission electron microscopy, scanning transmission electron microscopy, and electron dispersive X-ray elemental mapping analysis. The 3-5 nm MnO2 nanocrystals at mass loadings of 7.3-10.8 wt % are homogeneously distributed onto the HPCs, and the utilization efficiency of MnO2 on specific capacitance can be enhanced to 94-96 %. By combining the ultrahigh utilization efficiency of MnO2 and the conductive and ion-transport advantages of HPCs, MnO2 /HPC electrodes can achieve higher specific capacitance values (196 F g(-1) ) than those of pure carbon electrodes (60.8 F g(-1) ), and maintain their superior rate capability in neutral electrolyte solutions. The asymmetric supercapacitor consisting of a MnO2 /HPC cathode and a HPC anode shows an excellent performance with energy and power densities of 15.3 Wh kg(-1) and 19.8 kW kg(-1) , respectively, at a cell voltage of 2 V. Results obtained herein demonstrate the excellence of MnO2 /HPC nanocomposites as energy storage material and open an avenue to fabricate the next generation supercapacitors with both high power and energy densities. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recombinant Reflectin-Based Optical Materials

DTIC Science & Technology

2012-01-01

sili- con substrates were placed in a sealed plastic box. The RH was controlled using a Dydra electronic cigar humidifier and monitored using a Fisher...diffraction gratings to generate diffraction patterns. Nano-spheres and la- mellar microstructures of refCBA samples were observed by scanning electron ...samples were observed by scanning electron microscopy and atomic force microscopy. Despite the reduced complexity of the refCBA protein compared to natural

Scanning Electron Microanalysis and Analytical Challenges of Mapping Elements in Urban Atmospheric Particles

EPA Science Inventory

Elemental mapping with energy-dispersive X-ray spectroscopy (EDX) associated with scanning electron microscopy is highly useful for studying internally mixed atmospheric particles. Presented is a study of individual particles from urban airsheds and the analytical challenges in q...

Microstructure of milk

USDA-ARS?s Scientific Manuscript database

The fat and protein in milk may be examined by scanning electron microscopy, transmission electron microscopy, and confocal laser scanning microscopy, and any bacteria present may be viewed by light microscopy. The fat exists as globules, the bulk of the protein is in the form of casein micelles, a...

Three-Dimensional Intercalated Porous Graphene on Si(111)

NASA Astrophysics Data System (ADS)

Pham, Trung T.; Sporken, Robert

2018-02-01

Three-dimensional intercalated porous graphene has been formed on Si(111) by electron beam evaporation under appropriate conditions and its structural and electronic properties investigated in detail by reflection high-energy electron diffraction, x-ray photoemission spectroscopy, Raman spectroscopy, high-resolution scanning electron microscopy, atomic force microscopy, and scanning tunneling microscopy. The results show that the crystalline quality of the porous graphene depended not only on the substrate temperature but also on the SiC layer thickness during carbon atom deposition.

Scanning electron microscope/energy dispersive x ray analysis of impact residues in LDEF tray clamps

NASA Technical Reports Server (NTRS)

Bernhard, Ronald P.; Durin, Christian; Zolensky, Michael E.

1993-01-01

Detailed optical scanning of tray clamps is being conducted in the Facility for the Optical Inspection of Large Surfaces at JSC to locate and document impacts as small as 40 microns in diameter. Residues from selected impacts are then being characterized by Scanning Electron Microscopy/Energy Dispersive X-ray Analysis at CNES. Results from this analysis will be the initial step to classifying projectile residues into specific sources.

Comparison of macroscopic and microscopic (stereomicroscopy and scanning electron microscopy) features of bone lesions due to hatchet hacking trauma.

PubMed

Nogueira, Luísa; Quatrehomme, Gérald; Bertrand, Marie-France; Rallon, Christophe; Ceinos, Romain; du Jardin, Philippe; Adalian, Pascal; Alunni, Véronique

2017-03-01

This experimental study examined the lesions produced by a hatchet on human bones (tibiae). A total of 30 lesions were produced and examined macroscopically (naked eye) and by stereomicroscopy. 13 of them were also analyzed using scanning electron microscopy. The general shape of the lesion, both edges, both walls, the kerf floor and the extremities were described. The length and maximum width of the lesions were also recorded. The microscopic analysis of the lesions led to the description of a sharp-blunt mechanism. Specific criteria were identified (lateral pushing back, fragmentation of the upraising, fossa dug laterally to the edge and vertical striae) enabling the forensic expert to conclude that a hacking instrument was used. These criteria are easily identifiable using scanning electron microscopy, but can also be observed with stereomicroscopy. Overall, lateral pushing back and vertical striae visible using stereomicroscopy and scanning electron microscopy signal the use of a hacking tool.

Laser-scanning techniques for rapid ballistics identification

NASA Technical Reports Server (NTRS)

Woodburgy, R. C.; Nakich, R. B.

1974-01-01

Two different laser-scanning methods may be utilized. In each case scanned cylindrical bullet surface is displayed ""unwrapped'' on oscilloscope screen. Bullets are compared by photographing each display and superimposing negatives of two images. With some modifications bullets can be scanned and compared by superimposing images on screen of dual-beam oscilloscope.

Nanoscale patterning of two metals on silicon surfaces using an ABC triblock copolymer template.

PubMed

Aizawa, Masato; Buriak, Jillian M

2006-05-03

Patterning technologically important semiconductor interfaces with nanoscale metal films is important for applications such as metallic interconnects and sensing applications. Self-assembling block copolymer templates are utilized to pattern an aqueous metal reduction reaction, galvanic displacement, on silicon surfaces. Utilization of a triblock copolymer monolayer film, polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO), with two blocks capable of selective transport of different metal complexes to the surface (PEO and P2VP), allows for chemical discrimination and nanoscale patterning. Different regions of the self-assembled structure discriminate between metal complexes at the silicon surface, at which time they undergo the spontaneous reaction at the interface. Gold deposition from gold(III) compounds such as HAuCl4(aq) in the presence of hydrofluoric acid mirrors the parent block copolymer core structure, whereas silver deposition from Ag(I) salts such as AgNO3(aq) does the opposite, localizing exclusively under the corona. By carrying out gold deposition first and silver second, sub-100-nm gold features surrounded by silver films can be produced. The chemical selectivity was extended to other metals, including copper, palladium, and platinum. The interfaces were characterized by a variety of methods, including scanning electron microscopy, scanning Auger microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy.

Enhanced Imaging of Corrosion in Aircraft Structures with Reverse Geometry X-ray(registered tm)

NASA Technical Reports Server (NTRS)

Winfree, William P.; Cmar-Mascis, Noreen A.; Parker, F. Raymond

2000-01-01

The application of Reverse Geometry X-ray to the detection and characterization of corrosion in aircraft structures is presented. Reverse Geometry X-ray is a unique system that utilizes an electronically scanned x-ray source and a discrete detector for real time radiographic imaging of a structure. The scanned source system has several advantages when compared to conventional radiography. First, the discrete x-ray detector can be miniaturized and easily positioned inside a complex structure (such as an aircraft wing) enabling images of each surface of the structure to be obtained separately. Second, using a measurement configuration with multiple detectors enables the simultaneous acquisition of data from several different perspectives without moving the structure or the measurement system. This provides a means for locating the position of flaws and enhances separation of features at the surface from features inside the structure. Data is presented on aircraft specimens with corrosion in the lap joint. Advanced laminographic imaging techniques utilizing data from multiple detectors are demonstrated to be capable of separating surface features from corrosion in the lap joint and locating the corrosion in multilayer structures. Results of this technique are compared to computed tomography cross sections obtained from a microfocus x-ray tomography system. A method is presented for calibration of the detectors of the Reverse Geometry X-ray system to enable quantification of the corrosion to within 2%.

The utilization of drug-polymer interactions for improving the chemical stability of hot-melt extruded solid dispersions.

PubMed

Guo, Zhefei; Lu, Ming; Li, Yongcheng; Pang, Huishi; Lin, Ling; Liu, Xu; Wu, Chuanbin

2014-02-01

Interactions between drugs and polymers were utilized to lower the processing temperature of hot-melt extrusion (HME), and thus minimize the thermal degradation of heat-sensitive drugs during preparation of amorphous solid dispersions. Diflunisal (DIF), which would degrade upon melting, was selected as a model drug. Hydrogen bonds between DIF and polymeric carriers (PVP K30, PVP VA64, hydroxypropyl methylcellulose and Soluplus) were revealed by differential scanning calorimetry and Fourier transform infrared spectroscopy. The hot-melt extruded solid dispersion was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-performance liquid chromatography (HPLC). The results of hot-stage polar microscopy indicated that DIF was dissolved in molten polymers at 160°C, much lower than the melting point of DIF (215°C). At this temperature, amorphous solid dispersions were successfully produced by HME, as confirmed by XRD and SEM. The related impurities in amorphous solid dispersions detected by HPLC were lower than 0.3%, indicating that thermal degradation was effectively minimized. The dissolution of DIF from amorphous solid dispersions was significantly enhanced as compared with the pure crystalline drug. This technique based on drug-polymer interactions to prepare chemically stable amorphous solid dispersions by HME provides an attractive opportunity for development of heat-sensitive drugs. © 2013 Royal Pharmaceutical Society.

Two-dimensional simulation and modeling in scanning electron microscope imaging and metrology research.

PubMed

Postek, Michael T; Vladár, András E; Lowney, Jeremiah R; Keery, William J

2002-01-01

Traditional Monte Carlo modeling of the electron beam-specimen interactions in a scanning electron microscope (SEM) produces information about electron beam penetration and output signal generation at either a single beam-landing location, or multiple landing positions. If the multiple landings lie on a line, the results can be graphed in a line scan-like format. Monte Carlo results formatted as line scans have proven useful in providing one-dimensional information about the sample (e.g., linewidth). When used this way, this process is called forward line scan modeling. In the present work, the concept of image simulation (or the first step in the inverse modeling of images) is introduced where the forward-modeled line scan data are carried one step further to construct theoretical two-dimensional (2-D) micrographs (i.e., theoretical SEM images) for comparison with similar experimentally obtained micrographs. This provides an ability to mimic and closely match theory and experiment using SEM images. Calculated and/or measured libraries of simulated images can be developed with this technique. The library concept will prove to be very useful in the determination of dimensional and other properties of simple structures, such as integrated circuit parts, where the shape of the features is preferably measured from a single top-down image or a line scan. This paper presents one approach to the generation of 2-D simulated images and presents some suggestions as to their application to critical dimension metrology.

The Cost-Utility Analysis of PET-Scan in Diagnosis and Treatment of Non-Small Cell Lung Carcinoma in Iran.

PubMed

Akbari Sari, Ali; Ravaghi, Hamid; Mobinizadeh, Mohammadreza; Sarvari, Sima

2013-06-01

PET scan is a non-invasive, complex and expensive medical imaging technology that is normally used for the diagnosis and treatment of various diseases including lung cancer. The purpose of this study is to assess the cost effectiveness of this technology in the diagnosis and treatment of non- small cell lung carcinoma (NSCLC) in Iran. The main electronic databases including The Cochrane Library and Medline were searched to identify available evidence about the performance and effectiveness of technology. A standard decision tree model with seven strategies was used to perform the economic evaluation. Retrieved studies and expert opinion were used to estimate the cost of each treatment strategy in Iran. The costs were divided into three categories including capital costs (depreciation costs of buildings and equipment), staff costs and other expenses (including cost of consumables, running and maintenance costs). The costs were estimated in both IR-Rials and US-Dollars with an exchange rate of 10.000 IR Rials per one US Dollar according to the exchange rate in 2008. The total annual running cost of a PET scan was about 8850 to 13000 million Rials, (0.9 to 1.3 million US$). The average cost of performing a PET scan varied between 3 and 4.5 million Rials (300 to 450US$). The strategies 3 (mediastinoscopy alone) and 7 (mediastinoscopy after PET scan) were more cost-effective than other strategies, especially when the result of the CT-scan performed before PET scan was negative. The technical performance of PET scan is significantly higher than similar technologies for staging and treatment of NSCLC. In addition, it might slightly improve the treatment process and lead to a small level of increase in the quality adjusted life year (QALY) gained by these patients making it cost-effective for the treatment of NSCLC.

Neuroanatomy from Mesoscopic to Nanoscopic Scales: An Improved Method for the Observation of Semithin Sections by High-Resolution Scanning Electron Microscopy

PubMed Central

Rodríguez, José-Rodrigo; Turégano-López, Marta; DeFelipe, Javier; Merchán-Pérez, Angel

2018-01-01

Semithin sections are commonly used to examine large areas of tissue with an optical microscope, in order to locate and trim the regions that will later be studied with the electron microscope. Ideally, the observation of semithin sections would be from mesoscopic to nanoscopic scales directly, instead of using light microscopy and then electron microscopy (EM). Here we propose a method that makes it possible to obtain high-resolution scanning EM images of large areas of the brain in the millimeter to nanometer range. Since our method is compatible with light microscopy, it is also feasible to generate hybrid light and electron microscopic maps. Additionally, the same tissue blocks that have been used to obtain semithin sections can later be used, if necessary, for transmission EM, or for focused ion beam milling and scanning electron microscopy (FIB-SEM). PMID:29568263

Neuroanatomy from Mesoscopic to Nanoscopic Scales: An Improved Method for the Observation of Semithin Sections by High-Resolution Scanning Electron Microscopy.

PubMed

Rodríguez, José-Rodrigo; Turégano-López, Marta; DeFelipe, Javier; Merchán-Pérez, Angel

2018-01-01

Semithin sections are commonly used to examine large areas of tissue with an optical microscope, in order to locate and trim the regions that will later be studied with the electron microscope. Ideally, the observation of semithin sections would be from mesoscopic to nanoscopic scales directly, instead of using light microscopy and then electron microscopy (EM). Here we propose a method that makes it possible to obtain high-resolution scanning EM images of large areas of the brain in the millimeter to nanometer range. Since our method is compatible with light microscopy, it is also feasible to generate hybrid light and electron microscopic maps. Additionally, the same tissue blocks that have been used to obtain semithin sections can later be used, if necessary, for transmission EM, or for focused ion beam milling and scanning electron microscopy (FIB-SEM).

Study on the parameters of the scanning system for the 300 keV electron accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leo, K. W.; Chulan, R. M., E-mail: leo@nm.gov.my; Hashim, S. A.

2016-01-22

This paper describes the method to identify the magnetic coil parameters of the scanning system. This locally designed low energy electron accelerator with the present energy of 140 keV will be upgraded to 300 keV. In this accelerator, scanning system is required to deflect the energetic electron beam across a titanium foil in vertical and horizontal direction. The excitation current of the magnetic coil is determined by the energy of the electron beam. Therefore, the magnetic coil parameters must be identified to ensure the matching of the beam energy and excitation coil current. As the result, the essential parameters ofmore » the effective lengths for X-axis and Y-axis have been found as 0.1198 m and 0.1134 m and the required excitation coil currents which is dependenton the electron beam energies have be identified.« less

EBIC spectroscopy - A new approach to microscale characterization of deep levels in semi-insulating GaAs

NASA Technical Reports Server (NTRS)

Li, C.-J.; Sun, Q.; Lagowski, J.; Gatos, H. C.

1985-01-01

The microscale characterization of electronic defects in (SI) GaAs has been a challenging issue in connection with materials problems encountered in GaAs IC technology. The main obstacle which limits the applicability of high resolution electron beam methods such as Electron Beam-Induced Current (EBIC) and cathodoluminescence (CL) is the low concentration of free carriers in semiinsulating (SI) GaAs. The present paper provides a new photo-EBIC characterization approach which combines the spectroscopic advantages of optical methods with the high spatial resolution and scanning capability of EBIC. A scanning electron microscope modified for electronic characterization studies is shown schematically. The instrument can operate in the standard SEM mode, in the EBIC modes (including photo-EBIC and thermally stimulated EBIC /TS-EBIC/), and in the cathodo-luminescence (CL) and scanning modes. Attention is given to the use of CL, Photo-EBIC, and TS-EBIC techniques.

Refixation of Osteochondral Fractures by an Ultrasound-Activated Pin System – An Ovine In Vivo Examination Using CT and Scanning Electron Microscope

PubMed Central

H, Neumann; A.P, Schulz; S, Breer; A, Unger; B, Kienast

2015-01-01

Background: Osteochondral injuries, if not treated appropriately, often lead to severe osteoarthritis of the affected joint. Without refixation of the osteochondral fragment, human cartilage only repairs these defects imperfectly. All existing refixation systems for chondral defects have disadvantages, for instance bad MRI quality in the postoperative follow-up or low anchoring forces. To address the problem of reduced stability in resorbable implants, ultrasound-activated pins were developed. By ultrasound-activated melting of the tip of these implants a higher anchoring is assumed. Aim of the study was to investigate, if ultrasound-activated pins can provide a secure refixation of osteochondral fractures comparing to conventional screw and conventional, resorbable pin osteosynthesis. CT scans and scanning electron microscopy should proovegood refixation results with no further tissue damage by the melting of the ultrasound-activated pins in comparison to conventional osteosynthesis. Methods: Femoral osteochondral fragments in sheep were refixated with ultrasound-activated pins (SonicPin™), Ethipins® and screws (Asnis™). The quality of the refixated fragments was examined after three month of full weight bearing by CT scans and scanning electron microscopy of the cartilage surface. Results: The CT examination found almost no statistically significant difference in the quality of refixation between the three different implants used. Concerning the CT morphology, ultrasound-activated pins demonstrated at least the same quality in refixation of osteochondral fragments as conventional resorbable pins or screws. The scanning electron microscopy showed no major surface damage by the three implants, especially any postulated cartilage damage induced by the heat of the ultrasound-activated pin. The screws protruded above the cartilage surface, which may affect the opposingtibial surface. Conclusion: Using CT scans and scanning electron microscopy, the SonicPin™, the Ethipin® and screws were at least equivalent in refixation quality of osteochondral fragments. PMID:25674184

Design and performance of a beetle-type double-tip scanning tunneling microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaschinsky, Philipp; Coenen, Peter; Pirug, Gerhard

2006-09-15

A combination of a double-tip scanning tunneling microscope with a scanning electron microscope in ultrahigh vacuum environment is presented. The compact beetle-type design made it possible to integrate two independently driven scanning tunneling microscopes in a small space. Moreover, an additional level for coarse movement allows the decoupling of the translation and approach of the tunneling tip. The position of the two tips can be controlled from the millimeter scale down to 50 nm with the help of an add-on electron microscope. The instrument is capable of atomic resolution imaging with each tip.

[Scanning electron microscope study of chemically disinfected endodontic files].

PubMed

Navarro, G; Mateos, M; Navarro, J L; Canalda, C

1991-01-01

Forty stainless steel endodontic files were observed at scanning electron microscopy after being subjected to ten disinfection cycles of 10 minutes each one, immersed in different chemical disinfectants. Corrosion was not observed on the surface of the files in circumstances that this study was made.

Keggin-type polyoxometalate nanosheets: synthesis and characterization via scanning transmission electron microscopy.

PubMed

Hiyoshi, Norihito

2018-05-17

Polyoxometalate nanosheets were synthesized at the gas/liquid interface of an aqueous solution of Keggin-type silicotungstic acid, cesium chloride, and n-octylamine. The structure of the nanosheets was elucidated via aberration-corrected scanning transmission electron microscopy at the atomic and molecular levels.

Scanning electron microscopy analysis of corrosion degradation on tinplate substrates.

PubMed

Zumelzu, E; Cabezas, C; Vera, A

2003-01-01

The degradation of electrolytic tinplate used in food containers was analysed and evaluated, using scanning electron microscopy and electrochemical measurements of microcorrosion and ion dissolution by atomic absorption to prevent food contamination caused by metal traces and to increase the durability of such tinplates.

EVALUATION OF COMPUTER-CONTROLLED SCANNING ELECTRON MICROSCOPY APPLIED TO AN AMBIENT URBAN AEROSOL SAMPLE

EPA Science Inventory

Recent interest in monitoring and speciation of particulate matter has led to increased application of scanning electron microscopy (SEM) coupled with energy-dispersive x-ray analysis (EDX) to individual particle analysis. SEM/EDX provides information on the size, shape, co...

Path-separated electron interferometry in a scanning transmission electron microscope

NASA Astrophysics Data System (ADS)

Yasin, Fehmi S.; Harvey, Tyler R.; Chess, Jordan J.; Pierce, Jordan S.; McMorran, Benjamin J.

2018-05-01

We report a path-separated electron interferometer within a scanning transmission electron microscope. In this setup, we use a nanofabricated grating as an amplitude-division beamsplitter to prepare multiple spatially separated, coherent electron probe beams. We achieve path separations of 30 nm. We pass the  +1 diffraction order probe through amorphous carbon while passing the 0th and  ‑1 orders through vacuum. The probes are then made to interfere via imaging optics, and we observe an interference pattern at the CCD detector with up to 39.7% fringe visibility. We show preliminary experimental results in which the interference pattern was recorded during a 1D scan of the diffracted probes across a test phase object. These results qualitatively agree with a modeled interference predicted by an independent measurement of the specimen thickness. This experimental design can potentially be applied to phase contrast imaging and fundamental physics experiments, such as an exploration of electron wave packet coherence length.

Crystallization kinetics of the Cu{sub 50}Zr{sub 50} metallic glass under isothermal conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Qian; Jian, Zengyun, E-mail: jianzengyun@xatu.edu.cn; Xu, Junfeng

2016-12-15

Amorphous structure of the melt-spun Cu{sub 50}Zr{sub 50} amorphous alloy ribbons were confirmed by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). Isothermal crystallization kinetics of these alloy ribbons were investigated using differential scanning calorimetry (DSC). Besides, Arrhenius and Johnson-Mehl-Avrami (JMA) equations were utilized to obtain the isothermal crystallization kinetic parameters. As shown in the results, the local activation energy E{sub α} decreases by a large margin at the crystallized volume fraction α<0.1, which proves that crystallization process is increasingly easy. In addition, the local activation energy E{sub α} is basically constant at 0.1

The Effect of Baggase Ash on Fly Ash-Based Geopolimer Binder

NASA Astrophysics Data System (ADS)

Bayuaji, R.; Darmawan, M. S.; Husin, N. A.; Banugraha, R.; Alfi, M.; Abdullah, M. M. A. B.

2018-06-01

Geopolymer concrete is an environmentally friendly concrete. However, the geopolymer binder has a problem with setting time; mainly the composition comprises high calcium fly ash. This study utilized bagasse ash to improve setting time on fly ash-based geopolymer binder. The characterization of bagasse ash was carried out by using chemical and phase analysis, while the morphology characterization was examined by scanning electron microscope (SEM). The setting time test and the compressive strength test used standard ASTM C 191-04 and ASTM C39 / C39M respectively. The compressive strength of the samples determined at 3, 28 and 56 days. The result compared the requirement of the standards.

Fiducial marker application method for position alignment of in situ multimodal X-ray experiments and reconstructions

DOE PAGES

Shade, Paul A.; Menasche, David B.; Bernier, Joel V.; ...

2016-03-01

An evolving suite of X-ray characterization methods are presently available to the materials community, providing a great opportunity to gain new insight into material behavior and provide critical validation data for materials models. Two critical and related issues are sample repositioning during anin situexperiment and registration of multiple data sets after the experiment. To address these issues, a method is described which utilizes a focused ion-beam scanning electron microscope equipped with a micromanipulator to apply gold fiducial markers to samples for X-ray measurements. The method is demonstrated with a synchrotron X-ray experiment involvingin situloading of a titanium alloy tensile specimen.

Repulsive Interaction of Sulfide Layers on Compressor Impeller Blades Remanufactured Through Plasma Spray Welding

NASA Astrophysics Data System (ADS)

Chang, Y.; Zhou, D.; Wang, Y. L.; Huang, H. H.

2016-12-01

This study investigated the repulsive interaction of sulfide layers on compressor impeller blades remanufactured through plasma spray welding (PSW). Sulfide layers on the blades made of FV(520)B steel were prepared through multifarious corrosion experiments, and PSW was utilized to remanufacture blade specimens. The specimens were evaluated through optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, 3D surface topography, x-ray diffraction, ImageJ software analysis, Vicker's micro-hardness test and tensile tests. Results showed a large number of sulfide inclusions in the fusion zone generated by sulfide layers embodied into the molten pool during PSW. These sulfide inclusions seriously degraded the mechanical performance of the blades remanufactured through PSW.

Sub-nA spatially resolved conductivity profiling of surface and interface defects in ceria films

DOE PAGES

Farrow, Tim; Yang, Nan; Doria, Sandra; ...

2015-03-17

Spatial variability of conductivity in ceria is explored using scanning probe microscopy with galvanostatic control. Ionically blocking electrodes are used to probe the conductivity under opposite polarities to reveal possible differences in the defect structure across a thin film of CeO2. Data suggest the existence of a large spatial inhomogeneity that could give rise to constant phase elements during standard electrochemical characterization, potentially affecting the overall conductivity of films on the macroscale. The approach discussed here can also be utilized for other mixed ionic electronic conductor systems including memristors and electroresistors, as well as physical systems such as ferroelectric tunnelingmore » barriers« less

Electrical properties of Al-, Cu-, Zn- rice husk charcoal junctions

NASA Astrophysics Data System (ADS)

Dahonog, L. A.; Tapia, A. K. G.

2017-04-01

Rice husk in the Philippines is considered as an agricultural waste. In order to utilize the material, one common technique is to carbonize these rice husks to produce charcoal briquettes. These materials are porous in nature exhibiting electrical properties from carbon structures. In this study, rice husk charcoals (RHC) were deposited on different metal substrates (Al, Cu, Zn) via a simple solution casting method. The deposited RHC on metal substrates was observed using Scanning Electron Microscopy (SEM). The films were characterized using two-point probe technique and the I-V curves were plotted. Al-RHC films appear to deviate from an ohmic behaviour while Zn-RHC and Cu-RHC showed diode-like behaviours.

Morphological investigations of cells that adhered to the irregular patterned polydimethylsiloxane (PDMS) surface without reagents.

PubMed

Chung, Sung Hee; Min, Junhong

2009-07-01

Polydimethylsiloxane (PDMS) surface consisting irregular pattern was investigated to develop cell-based biochip using PDMS. PDMS surface was modified with nano- and micro-combined patterns using surface deformation technology. Hydrophobicity of nano-patterned PDMS surface was sustained. Nevertheless it has irregular patterns consisting of micro- and nano-patterns. According to atomic force microscopy (AFM), scanning electron microscopy (SEM) and confocal microscopy results by immunostaining method, human mammary epithelial cells (HMEC) adhered well on irregularly patterned surface without any reagents such as gelatin and collagen, compared to commercial culture dish. It implies PDMS material can be utilized as template for cell-based biochip without any reagents.

Phased Array Antenna Testbed Development at the NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Lambert, Kevin M.; Kubat, Gregory; Johnson, Sandra K.; Anzic, Godfrey

2003-01-01

Ideal phased array antennas offer advantages for communication systems, such as wide-angle scanning and multibeam operation, which can be utilized in certain NASA applications. However, physically realizable, electronically steered, phased array antennas introduce additional system performance parameters, which must be included in the evaluation of the system. The NASA Glenn Research Center (GRC) is currently conducting research to identify these parameters and to develop the tools necessary to measure them. One of these tools is a testbed where phased array antennas may be operated in an environment that simulates their use. This paper describes the development of the testbed and its use in characterizing a particular K-Band, phased array antenna.

Nanopore fabrication and characterization by helium ion microscopy

NASA Astrophysics Data System (ADS)

Emmrich, D.; Beyer, A.; Nadzeyka, A.; Bauerdick, S.; Meyer, J. C.; Kotakoski, J.; Gölzhäuser, A.

2016-04-01

The Helium Ion Microscope (HIM) has the capability to image small features with a resolution down to 0.35 nm due to its highly focused gas field ionization source and its small beam-sample interaction volume. In this work, the focused helium ion beam of a HIM is utilized to create nanopores with diameters down to 1.3 nm. It will be demonstrated that nanopores can be milled into silicon nitride, carbon nanomembranes, and graphene with well-defined aspect ratio. To image and characterize the produced nanopores, helium ion microscopy and high resolution scanning transmission electron microscopy were used. The analysis of the nanopores' growth behavior allows inferring on the profile of the helium ion beam.

Hybrid Dispersion Laser Scanner

PubMed Central

Goda, K.; Mahjoubfar, A.; Wang, C.; Fard, A.; Adam, J.; Gossett, D. R.; Ayazi, A.; Sollier, E.; Malik, O.; Chen, E.; Liu, Y.; Brown, R.; Sarkhosh, N.; Di Carlo, D.; Jalali, B.

2012-01-01

Laser scanning technology is one of the most integral parts of today's scientific research, manufacturing, defense, and biomedicine. In many applications, high-speed scanning capability is essential for scanning a large area in a short time and multi-dimensional sensing of moving objects and dynamical processes with fine temporal resolution. Unfortunately, conventional laser scanners are often too slow, resulting in limited precision and utility. Here we present a new type of laser scanner that offers ∼1,000 times higher scan rates than conventional state-of-the-art scanners. This method employs spatial dispersion of temporally stretched broadband optical pulses onto the target, enabling inertia-free laser scans at unprecedented scan rates of nearly 100 MHz at 800 nm. To show our scanner's broad utility, we use it to demonstrate unique and previously difficult-to-achieve capabilities in imaging, surface vibrometry, and flow cytometry at a record 2D raster scan rate of more than 100 kHz with 27,000 resolvable points. PMID:22685627

Local electric field direct writing – Electron-beam lithography and mechanism

DOE PAGES

Jiang, Nan; Su, Dong; Spence, John C. H.

2017-08-24

Local electric field induced by a focused electron probe in silicate glass thin films is evaluated in this paper by the migration of cations. Extremely strong local electric fields can be obtained by the focused electron probe from a scanning transmission electron microscope. As a result, collective atomic displacements occur. This newly revised mechanism provides an efficient tool to write patterned nanostructures directly, and thus overcome the low efficiency of the conventional electron-beam lithography. Applying this technique to silicate glass thin films, as an example, a grid of rods of nanometer dimension can be efficiently produced by rapidly scanning amore » focused electron probe. This nanopatterning is achieved through swift phase separation in the sample, without any post-development processes. The controlled phase separation is induced by massive displacements of cations (glass modifiers) within the glass-former network, driven by the strong local electric fields. The electric field is induced by accumulated charge within the electron probed region, which is generated by the excitation of atomic electrons by the incident electron. Throughput is much improved compared to other scanning probe techniques. Finally, the half-pitch spatial resolution of nanostructure in this particular specimen is 2.5 nm.« less

Local electric field direct writing – Electron-beam lithography and mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Nan; Su, Dong; Spence, John C. H.

Local electric field induced by a focused electron probe in silicate glass thin films is evaluated in this paper by the migration of cations. Extremely strong local electric fields can be obtained by the focused electron probe from a scanning transmission electron microscope. As a result, collective atomic displacements occur. This newly revised mechanism provides an efficient tool to write patterned nanostructures directly, and thus overcome the low efficiency of the conventional electron-beam lithography. Applying this technique to silicate glass thin films, as an example, a grid of rods of nanometer dimension can be efficiently produced by rapidly scanning amore » focused electron probe. This nanopatterning is achieved through swift phase separation in the sample, without any post-development processes. The controlled phase separation is induced by massive displacements of cations (glass modifiers) within the glass-former network, driven by the strong local electric fields. The electric field is induced by accumulated charge within the electron probed region, which is generated by the excitation of atomic electrons by the incident electron. Throughput is much improved compared to other scanning probe techniques. Finally, the half-pitch spatial resolution of nanostructure in this particular specimen is 2.5 nm.« less

Electronic properties of conductive pili of the metal-reducing bacterium Geobacter sulfurreducens probed by scanning tunneling microscopy.

PubMed

Veazey, Joshua P; Reguera, Gemma; Tessmer, Stuart H

2011-12-01

The metal-reducing bacterium Geobacter sulfurreducens produces conductive protein appendages known as "pilus nanowires" to transfer electrons to metal oxides and to other cells. These processes can be harnessed for the bioremediation of toxic metals and the generation of electricity in bioelectrochemical cells. Key to these applications is a detailed understanding of how these nanostructures conduct electrons. However, to the best of our knowledge, their mechanism of electron transport is not known. We used the capability of scanning tunneling microscopy (STM) to probe conductive materials with higher spatial resolution than other scanning probe methods to gain insights into the transversal electronic behavior of native, cell-anchored pili. Despite the presence of insulating cellular components, the STM topography resolved electronic molecular substructures with periodicities similar to those reported for the pilus shaft. STM spectroscopy revealed electronic states near the Fermi level, consistent with a conducting material, but did not reveal electronic states expected for cytochromes. Furthermore, the transversal conductance was asymmetric, as previously reported for assemblies of helical peptides. Our results thus indicate that the Geobacter pilus shaft has an intrinsic electronic structure that could play a role in charge transport.

The Effect of Scan Length on the Structure and Mechanical Properties of Electron Beam-Melted Ti-6Al-4V

NASA Astrophysics Data System (ADS)

Everhart, Wesley; Dinardo, Joseph; Barr, Christian

2017-02-01

Electron beam melting (EBM) is a powder bed fusion-based additive manufacturing process in which selective areas of a layer of powder are melted with an electron beam and a part is built layer by layer. EBM scanning strategies within the Arcam AB® A2X EBM system rely upon governing relationships between the scan length of the beam path, the beam current, and speed. As a result, a large parameter process window exists for Ti-6Al-4V. Many studies have reviewed various properties of EBM materials without accounting for this effect. The work performed in this study demonstrates the relationship between scan length and the resulting density, microstructure, and mechanical properties of EBM-produced Ti-6Al-4V using the scanning strategies set by the EBM control software. This emphasizes the criticality of process knowledge and careful experimental design, and provides an alternate explanation for reported orientation-influenced strength differences.

Development of a c-scan photoacoutsic imaging probe for prostate cancer detection

NASA Astrophysics Data System (ADS)

Valluru, Keerthi S.; Chinni, Bhargava K.; Rao, Navalgund A.; Bhatt, Shweta; Dogra, Vikram S.

2011-03-01

Prostate cancer is the second leading cause of death in American men after lung cancer. The current screening procedures include Digital Rectal Exam (DRE) and Prostate Specific Antigen (PSA) test, along with Transrectal Ultrasound (TRUS). All suffer from low sensitivity and specificity in detecting prostate cancer in early stages. There is a desperate need for a new imaging modality. We are developing a prototype transrectal photoacoustic imaging probe to detect prostate malignancies in vivo that promises high sensitivity and specificity. To generate photoacoustic (PA) signals, the probe utilizes a high energy 1064 nm laser that delivers light pulses onto the prostate at 10Hz with 10ns duration through a fiber optic cable. The designed system will generate focused C-scan planar images using acoustic lens technology. A 5 MHz custom fabricated ultrasound sensor array located in the image plane acquires the focused PA signals, eliminating the need for any synthetic aperture focusing. The lens and sensor array design was optimized towards this objective. For fast acquisition times, a custom built 16 channel simultaneous backend electronics PCB has been developed. It consists of a low-noise variable gain amplifier and a 16 channel ADC. Due to the unavailability of 2d ultrasound arrays, in the current implementation several B-scan (depth-resolved) data is first acquired by scanning a 1d array, which is then processed to reconstruct either 3d volumetric images or several C-scan planar images. Experimental results on excised tissue using a in-vitro prototype of this technology are presented to demonstrate the system capability in terms of resolution and sensitivity.

Heart CT scan

MedlinePlus

... Computed tomography scan - heart; Calcium scoring; Multi-detector CT scan - heart; Electron beam computed tomography - heart; Agatston ... table that slides into the center of the CT scanner. You will lie on your back with ...

An inexpensive approach for bright-field and dark-field imaging by scanning transmission electron microscopy in scanning electron microscopy.

PubMed

Patel, Binay; Watanabe, Masashi

2014-02-01

Scanning transmission electron microscopy in scanning electron microscopy (STEM-in-SEM) is a convenient technique for soft materials characterization. Various specimen-holder geometries and detector arrangements have been used for bright-field (BF) STEM-in-SEM imaging. In this study, to further the characterization potential of STEM-IN-SEM, a new specimen holder has been developed to facilitate direct detection of BF signals and indirect detection of dark-field (DF) signals without the need for substantial instrument modification. DF imaging is conducted with the use of a gold (Au)-coated copper (Cu) plate attached to the specimen holder which directs highly scattered transmitted electrons to an off-axis yttrium-aluminum-garnet (YAG) detector. A hole in the copper plate allows for BF imaging with a transmission electron (TE) detector. The inclusion of an Au-coated Cu plate enhanced DF signal intensity. Experiments validating the acquisition of true DF signals revealed that atomic number (Z) contrast may be achieved for materials with large lattice spacing. However, materials with small lattice spacing still exhibit diffraction contrast effects in this approach. The calculated theoretical fine probe size is 1.8 nm. At 30 kV, in this indirect approach, DF spatial resolution is limited to 3.2 nm as confirmed experimentally.

Sample preparation methods for scanning electron microscopy of homogenized Al-Mg-Si billets: A comparative study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Österreicher, Johannes Albert; Kumar, Manoj

Characterization of Mg-Si precipitates is crucial for optimizing the homogenization heat treatment of Al-Mg-Si alloys. Although sample preparation is key for high quality scanning electron microscopy imaging, most common methods lead to dealloying of Mg-Si precipitates. In this article we systematically evaluate different sample preparation methods: mechanical polishing, etching with various reagents, and electropolishing using different electrolytes. We demonstrate that the use of a nitric acid and methanol electrolyte for electropolishing a homogenized Al-Mg-Si alloy prevents the dissolution of Mg-Si precipitates, resulting in micrographs of higher quality. This preparation method is investigated in depth and the obtained scanning electron microscopymore » images are compared with transmission electron micrographs: the shape and size of Mg-Si precipitates appear very similar in either method. The scanning electron micrographs allow proper identification and measurement of the Mg-Si phases including needles with lengths of roughly 200 nm. These needles are β″ precipitates as confirmed by high resolution transmission electron microscopy. - Highlights: •Secondary precipitation in homogenized 6xxx Al alloys is crucial for extrudability. •Existing sample preparation methods for SEM are improvable. •Electropolishing with nitric acid/methanol yields superior quality in SEM. •The obtained micrographs are compared to TEM micrographs.« less

Scanning electron microscopy of adult Echinoparyphium recurvatum (Von Linstow, 1873) (Digenea: Echinostomatidae) from Britain.

PubMed

McCarthy, A M

2011-12-01

The surface topography of 15-day-old adult Echinoparyphium recurvatum (Von Linstow, 1873) sensu stricto, from an isolate of the parasite utilizing Lymnaea peregra as first intermediate host in southern England, is described and illustrated using scanning electron microscopy, and is compared to those of other Echinoparyphium species from Europe, and with those of E. recurvatum of East Asian origin. The general morphology of tegumental features was found to be very similar to that of worms of the same age observed in a previous study on a Korean isolate of E. recurvatum. Comparison of collar and body spination of E. recurvatum with other 45-collar-spined members of the genus in Europe revealed some significant differences in morphology. Collar spines of E. recurvatum were found to be shorter and more pointed than those of Echinoparyphium mordwilkoi. The body spines of E. recurvatum are rounded and scale-like, extending just beyond the ventral sucker, contrasting with the pointed, thorn-shaped body spines of E. mordwilkoi, extending posteriorly to the level of the second testis. Body spine shape and distribution in E. recurvatum were found to be more similar to those of Echinoparyphium pseudorecurvatum. The value of SEM studies in elucidating the relationship between members of the genus Echinoparyphium in Britain/Europe and those in Africa, Asia and North America is suggested.

An in-vitro evaluation of the effect of 980 nm diode laser irradiation on intra-canal dentin surface and dentinal tubule openings after biomechanical preparation: Scanning electron microscopic study

PubMed Central

Jhingan, Pulkit; Sandhu, Meera; Jindal, Garima; Goel, Deepti; Sachdev, Vinod

2015-01-01

Context: Very recently, diode laser has been used for disinfecting the root canals in endodontic treatment and increasing its success rate and longevity utilizing the thermal effect of laser on surrounding tissues. Aims: The aim of this study is to evaluate the effect of 980 nm laser irradiation on intra-canal dentin surface – scanning electron microscopic (SEM) - in-vitro study. Methods: A total of 40 single-rooted freshly extracted permanent teeth were collected. Teeth were sectioned at the cemento-enamel junction using diamond disc. Root canals of all samples were prepared using hand ProTaper, which were randomly assigned into two groups (n = 20 each). Group 1: Receiving no treatment after biomechanical preparation; Group 2: 980 nm diode laser-treated root canals. Teeth were prepared for SEM analysis to check the size of intra-canal dentinal tubule openings. Statistical Analysis Used: Data were analyzed using SPSS V.16 software and compared using Levene's and independent t-test. Results: On statistical analysis, width of intracanal dentinal tubule openings in Group 1 (control) was significantly higher than those observed in Group 2 (diode laser-treated) (P < 0.001). Conclusion: This study showed that the application of 980 nm diode laser on intra-radicular dentin resulted in ultrastructural alterations resulting in melting of dentin. PMID:26097338

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Bingbing; Knopf, Daniel A.; China, Swarup

Heterogeneous ice nucleation is a physical chemistry process of critical relevance to a range of topics in the fundamental and the applied sciences and technologies. Heterogeneous ice nucleation remains insufficiently understood. This is in part due to the lack of experimental methods capable of in situ visualization of ice formation over nucleating substrates with microscopically characterized morphology and composition. We present development, validation and first applications of a novel electron microscopy platform allowing observation of individual ice nucleation events at temperature and relative humidity (RH) relevant for ice formation in a broad range of environmental and applied technology processes. Themore » approach utilizes a custom-built ice nucleation cell, interfaced with an Environmental Scanning Electron Microscope (IN-ESEM system). The IN-ESEM system allows dynamic observations of individual ice formation events over particles of atmospheric relevance and determination of the ice nucleation mechanisms. Additional IN-ESEM experiments allow examination of the location of ice formation on the surface of individual particles and micro-spectroscopy analysis of the ice nucleating particles (INPs). This includes elemental composition detected by the energy dispersed analysis of X-rays (EDX), speciation of the organic content in particles using scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS), and Helium ion microscopy (HeIM). The capabilities of the IN-ESEM experimental platform are demonstrated first on laboratory standards and then by chemical imaging of INPs using a complex sample of ambient particles.« less

Analysis of Mesa Dislocation Gettering in HgCdTe/CdTe/Si(211) by Scanning Transmission Electron Microscopy

NASA Astrophysics Data System (ADS)

Jacobs, R. N.; Stoltz, A. J.; Benson, J. D.; Smith, P.; Lennon, C. M.; Almeida, L. A.; Farrell, S.; Wijewarnasuriya, P. S.; Brill, G.; Chen, Y.; Salmon, M.; Zu, J.

2013-11-01

Due to its strong infrared absorption and variable band-gap, HgCdTe is the ideal detector material for high-performance infrared focal-plane arrays (IRFPAs). Next-generation IRFPAs will utilize dual-color high-definition formats on large-area substrates such as Si or GaAs. However, heteroepitaxial growth on these substrates is plagued by high densities of lattice-mismatch-induced threading dislocations (TDs) that ultimately reduce IRFPA operability. Previously we demonstrated a postgrowth technique with the potential to eliminate or move TDs such that they have less impact on detector operability. In this technique, highly reticulated mesa structures are produced in as-grown HgCdTe epilayers, and then subjected to thermal cycle annealing. To fully exploit this technique, better understanding of the inherent mechanism is required. In this work, we employ scanning transmission electron microscopy (STEM) analysis of HgCdTe/CdTe/Si(211) samples prepared by focused ion beam milling. A key factor is the use of defect-decorated samples, which allows for a correlation of etch pits observed on the surface with underlying dislocation segments viewed in cross-section STEM images. We perform an analysis of these dislocations in terms of the general distribution, density, and mobility at various locations within the mesa structures. Based on our observations, we suggest factors that contribute to the underlying mechanism for dislocation gettering.

Co- and Ce/Co-coated ferritic stainless steel as interconnect material for Intermediate Temperature Solid Oxide Fuel Cells

NASA Astrophysics Data System (ADS)

Falk-Windisch, Hannes; Claquesin, Julien; Sattari, Mohammad; Svensson, Jan-Erik; Froitzheim, Jan

2017-03-01

Chromium species volatilization, oxide scale growth, and electrical scale resistance were studied at 650 and 750 °C for thin metallic Co- and Ce/Co-coated steels intended to be utilized as the interconnect material in Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFC). Mass gain was recorded to follow oxidation kinetics, chromium evaporation was measured using the denuder technique and Area Specific Resistance (ASR) measurements were carried out on 500 h pre-exposed samples. The microstructure of thermally grown oxide scales was characterized using Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), and Energy Dispersive X-Ray Analysis (EDX). The findings of this study show that a decrease in temperature not only leads to thinner oxide scales and less Cr vaporization but also to a significant change in the chemical composition of the oxide scale. Very low ASR values (below 10 mΩ cm2) were measured for both Co- and Ce/Co-coated steel at 650 and 750 °C, indicating that the observed change in the chemical composition of the Co spinel does not have any noticeable influence on the ASR. Instead it is suggested that the Cr2O3 scale is expected to be the main contributor to the ASR, even at temperatures as low as 650 °C.

Transfer doping of single isolated nanodiamonds, studied by scanning probe microscopy techniques.

PubMed

Bolker, Asaf; Saguy, Cecile; Kalish, Rafi

2014-09-26

The transfer doping of diamond surfaces has been applied in various novel two-dimensional electronic devices. Its extension to nanodiamonds (ND) is essential for ND-based applications in many fields. In particular, understanding the influence of the crystallite size on transfer doping is desirable. Here, we report the results of a detailed study of the electronic energetic band structure of single, isolated transfer-doped nanodiamonds with nanometric resolution using a combination of scanning tunneling spectroscopy and Kelvin force microscopy measurements. The results show how the band gap, the valence band maximum, the electron affinity and the work function all depend on the ND's size and nanoparticle surface properties. The present analysis, which combines information from both scanning tunneling spectroscopy and Kelvin force microscopy, should be applicable to any nanoparticle or surface that can be measured with scanning probe techniques.

Differences between Subjective Balanced Occlusion and Measurements Reported With T-Scan III

PubMed Central

Lila-Krasniqi, Zana; Shala, Kujtim; Krasniqi, Teuta Pustina; Bicaj, Teuta; Ahmedi, Enis; Dula, Linda; Dragusha, Arlinda Tmava; Guguvcevski, Ljuben

2017-01-01

BACKGROUND: The aetiology of Temporomandibular disorder is multifactorial, and numerous studies have addressed that occlusion may be of great importance in the pathogenesis of Temporomandibular disorder. AIM: The aim of this study is to determine if any direct relationship exists between balanced occlusion and Temporomandibular disorder and to evaluate the differences between subjective balanced occlusion and measurements reported with T-scan III electronic system. MATERIAL AND METHODS: A total of 54 subjects were divided into three groups, selection based on anamnesis-responded to a Fonseca questionnaire and clinical measurements analysed with electronic system T-scan III. In the I study group were participants with fixed dentures with prosthetic ceramic restorations. In the II study group were symptomatic participants with TMD. In the third control group were healthy participants with full arch dentition that completed a subjective questionnaire that documented the absence of jaw pain, joint noise, locking and subjects without a history of TMD. The occlusal balance was reported subjectively through Fonseca questionnaire and compared with occlusion analysed with electronic system T-scan III. RESULTS: For attributive data were used percentage of the structure. Differences in P < 0.05 were considered significant. After distributing attributive data of occlusal balance subjectively reported and compared with measurements analysed with electronic system T-scan III were found significant difference P < 0.001 in all three groups. CONCLUSION: In our study, it was concluded that there were statistically significant differences of balanced occlusion in all three groups. Also it was concluded that subjective data are not exact with measurements reported with electronic device T-scan III. PMID:28932311

Low-Temperature Scanning Capacitance Probe for Imaging Electron Motion

NASA Astrophysics Data System (ADS)

Bhandari, S.; Westervelt, R. M.

2014-12-01

Novel techniques to probe electronic properties at the nanoscale can shed light on the physics of nanoscale devices. In particular, studying the scattering of electrons from edges and apertures at the nanoscale and imaging the electron profile in a quantum dot, have been of interest [1]. In this paper, we present the design and implementation of a cooled scanning capacitance probe that operates at liquid He temperatures to image electron waves in nanodevices. The conducting tip of a scanned probe microscope is held above the nanoscale structure, and an applied sample-to-tip voltage creates an image charge that is measured by a cooled charge amplifier [2] adjacent to the tip. The circuit is based on a low-capacitance, high- electron-mobility transistor (Fujitsu FHX35X). The input is a capacitance bridge formed by a low capacitance pinched-off HEMT transistor and tip-sample capacitance. We have achieved low noise level (0.13 e/VHz) and high spatial resolution (100 nm) for this technique, which promises to be a useful tool to study electronic behavior in nanoscale devices.

The Effect of Electron Beam Irradiation in Environmental Scanning Transmission Electron Microscopy of Whole Cells in Liquid.

PubMed

Hermannsdörfer, Justus; Tinnemann, Verena; Peckys, Diana B; de Jonge, Niels

2016-06-01

Whole cells can be studied in their native liquid environment using electron microscopy, and unique information about the locations and stoichiometry of individual membrane proteins can be obtained from many cells thus taking cell heterogeneity into account. Of key importance for the further development of this microscopy technology is knowledge about the effect of electron beam radiation on the samples under investigation. We used environmental scanning electron microscopy (ESEM) with scanning transmission electron microscopy (STEM) detection to examine the effect of radiation for whole fixed COS7 fibroblasts in liquid. The main observation was the localization of nanoparticle labels attached to epidermal growth factor receptors (EGFRs). It was found that the relative distances between the labels remained mostly unchanged (<1.5%) for electron doses ranging from the undamaged native state at 10 e-/Å2 toward 103 e-/Å2. This dose range was sufficient to determine the EGFR locations with nanometer resolution and to distinguish between monomers and dimers. Various different forms of radiation damage became visible at higher doses, including severe dislocation, and the dissolution of labels.

Fast imaging with inelastically scattered electrons by off-axis chromatic confocal electron microscopy.

PubMed

Zheng, Changlin; Zhu, Ye; Lazar, Sorin; Etheridge, Joanne

2014-04-25

We introduce off-axis chromatic scanning confocal electron microscopy, a technique for fast mapping of inelastically scattered electrons in a scanning transmission electron microscope without a spectrometer. The off-axis confocal mode enables the inelastically scattered electrons to be chromatically dispersed both parallel and perpendicular to the optic axis. This enables electrons with different energy losses to be separated and detected in the image plane, enabling efficient energy filtering in a confocal mode with an integrating detector. We describe the experimental configuration and demonstrate the method with nanoscale core-loss chemical mapping of silver (M4,5) in an aluminium-silver alloy and atomic scale imaging of the low intensity core-loss La (M4,5@840  eV) signal in LaB6. Scan rates up to 2 orders of magnitude faster than conventional methods were used, enabling a corresponding reduction in radiation dose and increase in the field of view. If coupled with the enhanced depth and lateral resolution of the incoherent confocal configuration, this offers an approach for nanoscale three-dimensional chemical mapping.

Ultra-thin resin embedding method for scanning electron microscopy of individual cells on high and low aspect ratio 3D nanostructures.

PubMed

Belu, A; Schnitker, J; Bertazzo, S; Neumann, E; Mayer, D; Offenhäusser, A; Santoro, F

2016-07-01

The preparation of biological cells for either scanning or transmission electron microscopy requires a complex process of fixation, dehydration and drying. Critical point drying is commonly used for samples investigated with a scanning electron beam, whereas resin-infiltration is typically used for transmission electron microscopy. Critical point drying may cause cracks at the cellular surface and a sponge-like morphology of nondistinguishable intracellular compartments. Resin-infiltrated biological samples result in a solid block of resin, which can be further processed by mechanical sectioning, however that does not allow a top view examination of small cell-cell and cell-surface contacts. Here, we propose a method for removing resin excess on biological samples before effective polymerization. In this way the cells result to be embedded in an ultra-thin layer of epoxy resin. This novel method highlights in contrast to standard methods the imaging of individual cells not only on nanostructured planar surfaces but also on topologically challenging substrates with high aspect ratio three-dimensional features by scanning electron microscopy. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

TU-F-18A-06: Dual Energy CT Using One Full Scan and a Second Scan with Very Few Projections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, T; Zhu, L

Purpose: The conventional dual energy CT (DECT) requires two full CT scans at different energy levels, resulting in dose increase as well as imaging errors from patient motion between the two scans. To shorten the scan time of DECT and thus overcome these drawbacks, we propose a new DECT algorithm using one full scan and a second scan with very few projections by preserving structural information. Methods: We first reconstruct a CT image on the full scan using a standard filtered-backprojection (FBP) algorithm. We then use a compressed sensing (CS) based iterative algorithm on the second scan for reconstruction frommore » very few projections. The edges extracted from the first scan are used as weights in the Objectives: function of the CS-based reconstruction to substantially improve the image quality of CT reconstruction. The basis material images are then obtained by an iterative image-domain decomposition method and an electron density map is finally calculated. The proposed method is evaluated on phantoms. Results: On the Catphan 600 phantom, the CT reconstruction mean error using the proposed method on 20 and 5 projections are 4.76% and 5.02%, respectively. Compared with conventional iterative reconstruction, the proposed edge weighting preserves object structures and achieves a better spatial resolution. With basis materials of Iodine and Teflon, our method on 20 projections obtains similar quality of decomposed material images compared with FBP on a full scan and the mean error of electron density in the selected regions of interest is 0.29%. Conclusion: We propose an effective method for reducing projections and therefore scan time in DECT. We show that a full scan plus a 20-projection scan are sufficient to provide DECT images and electron density with similar quality compared with two full scans. Our future work includes more phantom studies to validate the performance of our method.« less

Nondestructive Testing As a Tool in the Space Shuttle Columbia Accident Investigation

NASA Technical Reports Server (NTRS)

McDanels, Steve

2008-01-01

Nondestructive testing (NDT) played a crucial role in determining the Columbia tragedy's cause. Over 84,000 pieces of debris were recovered; hundreds were subsequently subjected to NDT and materials analysis. Visual NDT of the debris revealed localized areas of damage such as erosion, excessive heating, knife edging and mechanical damage. Three-dimensional reconstructions were made of the left wing leading edge, utilizing a tripod-mounted laser scanning head and focused laser beam, and an advanced topometric optical scanner (ATOS) with digital white light to scan complex-shaped debris, producing monochrome 3-D models. Texture mapping provided a means to capture true colors of the debris and superimpose them on the scanned images. Uniform deposits were found over large portions of debris, obscuring underlying materials. To determine what was beneath, inverse radiography was enlisted. The radiographs guided investigators to where samples should be taken. To ascertain compositions, these samples were subjected to analytical testing, including energy dispersive X-ray spectroscopy and electron microprobe analysis. This combination of visual evidence, radiography, virtual reconstruction, and materials analysis allowed the forensic scientists to verify that a breach occurred in the leading edge of the left wing, the path the plasma followed, and the sequence of events that led to the loss.

The research on calibration methods of dual-CCD laser three-dimensional human face scanning system

NASA Astrophysics Data System (ADS)

Wang, Jinjiang; Chang, Tianyu; Ge, Baozhen; Tian, Qingguo; Yang, Fengting; Shi, Shendong

2013-09-01

In this paper, on the basis of considering the performance advantages of two-step method, we combines the stereo matching of binocular stereo vision with active laser scanning to calibrate the system. Above all, we select a reference camera coordinate system as the world coordinate system and unity the coordinates of two CCD cameras. And then obtain the new perspective projection matrix (PPM) of each camera after the epipolar rectification. By those, the corresponding epipolar equation of two cameras can be defined. So by utilizing the trigonometric parallax method, we can measure the space point position after distortion correction and achieve stereo matching calibration between two image points. Experiments verify that this method can improve accuracy and system stability is guaranteed. The stereo matching calibration has a simple process with low-cost, and simplifies regular maintenance work. It can acquire 3D coordinates only by planar checkerboard calibration without the need of designing specific standard target or using electronic theodolite. It is found that during the experiment two-step calibration error and lens distortion lead to the stratification of point cloud data. The proposed calibration method which combining active line laser scanning and binocular stereo vision has the both advantages of them. It has more flexible applicability. Theory analysis and experiment shows the method is reasonable.

Direct measurement of the Goos-Hänchen shift using a scanning quadrant detector and a polarization maintaining fiber.

PubMed

Yallapragada, Venkata Jayasurya; Mulay, Gajendra L; Rao, Ch N; Ravishankar, Ajith P; Achanta, Venu Gopal

2016-10-01

High precision measurements of optical beam shifts are important in various fields including sensing, atomic force microscopy, and measuring beam shifts at interfaces. Sub-micron shifts are generally measured by indirect techniques such as weak measurements. We demonstrate a straightforward and robust measurement scheme for the shift, based on a scanning quadrant photodiode (QPD) that is biased using a low noise electronic circuit. The shift is measured with respect to a reference beam that is co-propagating with the signal beam. Thus, the shift of the signal beam is readout directly as the difference between the x-intercepts of the QPD scan plot of the signal and reference beams versus the position of the detector. To measure the beam shift, we use polarization multiplexing scheme where the p-polarized signal and s-polarized reference beams are modulated at two different frequencies and co-launched into a polarization-maintaining fiber. Both the signal and reference beam positions are readout by two lock-in amplifiers simultaneously. In order to demonstrate the utility of this method, we perform a direct measurement of Goos-Hänchen shift of a beam that is reflected from a plane gold surface. Accuracy of 150 nm is achieved using this technique.

Direct measurement of the Goos-Hänchen shift using a scanning quadrant detector and a polarization maintaining fiber

NASA Astrophysics Data System (ADS)

Yallapragada, Venkata Jayasurya; Mulay, Gajendra L.; Rao, Ch. N.; Ravishankar, Ajith P.; Achanta, Venu Gopal

2016-10-01

High precision measurements of optical beam shifts are important in various fields including sensing, atomic force microscopy, and measuring beam shifts at interfaces. Sub-micron shifts are generally measured by indirect techniques such as weak measurements. We demonstrate a straightforward and robust measurement scheme for the shift, based on a scanning quadrant photodiode (QPD) that is biased using a low noise electronic circuit. The shift is measured with respect to a reference beam that is co-propagating with the signal beam. Thus, the shift of the signal beam is readout directly as the difference between the x-intercepts of the QPD scan plot of the signal and reference beams versus the position of the detector. To measure the beam shift, we use polarization multiplexing scheme where the p-polarized signal and s-polarized reference beams are modulated at two different frequencies and co-launched into a polarization-maintaining fiber. Both the signal and reference beam positions are readout by two lock-in amplifiers simultaneously. In order to demonstrate the utility of this method, we perform a direct measurement of Goos-Hänchen shift of a beam that is reflected from a plane gold surface. Accuracy of 150 nm is achieved using this technique.

Minority carrier diffusion length and edge surface-recombination velocity in InP

NASA Technical Reports Server (NTRS)

Hakimzadeh, Roshanak; Bailey, Sheila G.

1993-01-01

A scanning electron microscope was used to obtain the electron-beam-induced current (EBIC) profiles in InP specimens containing a Schottky barrier perpendicular to the scanned (edge) surface. An independent technique was used to measure the edge surface-recombination velocity. These values were used in a fit of the experimental EBIC data with a theoretical expression for normalized EBIC (Donolato, 1982) to obtain the electron (minority carrier) diffusion length.

Choice of range-energy relationship for the analysis of electron-beam-induced-current line scans

NASA Astrophysics Data System (ADS)

Luke, Keung, L.

1994-07-01

The electron range in a material is an important parameter in the analysis of electron-beam-induced-current (EBIC) line scans. Both the Kanaya-Okayama (KO) and Everhart-Hoff (EH) range-energy relationships have been widely used by investigators for this purpose. Although the KO range is significantly larer than the EH range, no study has been done to examine the effect of choosing one range over the other on the values of the surface recombination velocity S(sub T) and minority-carrier diffusion length L evaluated from EBICF line scans. Such a study has been carried out, focusing on two major questions: (1) When the KO range is used in different reported methods to evaluate either or both S(sub T) and L from EBIC line scans, how different are their values thus determined in comparison to those using the EH range?; (2) from EBIC line scans of a given material, is there a way to discriminate between the KO and the EH ranges which should be used to analyze these scans? Answers to these questions are presented to assist investigators in extracting more reliable values of either or both S(sub T) and L and in finding the right range to use in the analysis of these line scans.

Serial block face scanning electron microscopy--the future of cell ultrastructure imaging.

PubMed

Hughes, Louise; Hawes, Chris; Monteith, Sandy; Vaughan, Sue

2014-03-01

One of the major drawbacks in transmission electron microscopy has been the production of three-dimensional views of cells and tissues. Currently, there is no one suitable 3D microscopy technique that answers all questions and serial block face scanning electron microscopy (SEM) fills the gap between 3D imaging using high-end fluorescence microscopy and the high resolution offered by electron tomography. In this review, we discuss the potential of the serial block face SEM technique for studying the three-dimensional organisation of animal, plant and microbial cells.

Realistic representation of Bacillus subtilis biofilms architecture using combined microscopy (CLSM, ESEM and FESEM).

PubMed

Bridier, A; Meylheuc, T; Briandet, R

2013-05-01

In this contribution, we used a set of microscopic techniques including confocal laser scanning microscopy (CLSM), environmental scanning electron microscopy (ESEM) and field emission scanning electron microscopy (FESEM) to analyze the three-dimensional spatial arrangement of cells and their surrounding matrix in Bacillus subtilis biofilm. The combination of the different techniques enabled a deeper and realistic deciphering of biofilm architecture by providing the opportunity to overcome the limits of each single technique. Copyright © 2013 Elsevier Ltd. All rights reserved.

Low-temperature and conventional scanning electron microscopy of human urothelial neoplasms.

PubMed

Hopkins, D M; Morris, J A; Oates, K; Huddart, H; Staff, W G

1989-05-01

The appearance of neoplastic human urothelium viewed by low-temperature scanning electron microscopy (LTSEM) and conventional scanning electron microscopy (CSEM) was compared. Fixed, dehydrated neoplastic cells viewed by CSEM had well-defined, often raised cell junctions; no intercellular gaps; and varying degrees of pleomorphic surface microvilli. The frozen hydrated material viewed by LTSEM, however, was quite different. The cells had a flat or dimpled surface, but no microvilli. There were labyrinthine lateral processes which interdigitated with those of adjacent cells and outlined large intercellular gaps. The process of fixation and dehydration will inevitably distort cell contours and on theoretical grounds, the images of frozen hydrated material should more closely resemble the in vivo appearance.

Use of light, scanning electron microscopy and bioassays to evaluate parasitism by entomopathogenic fungi of the red scale insect of palms (Phoenicococcus marlatti Ckll., 1899).

PubMed

Asensio, L; Lopez-Llorca, L V; López-Jiménez, J A

2005-01-01

We have evaluated the parasitism of the red scale insect of the date palm (Phoenicococcus marlatti) by entomopathogenic fungi, using light microscopy (LM), scanning electron microscopy (SEM) and low temperature scanning electron microscopy (LTSEM). Beauveria bassiana, Lecanicillium dimorphum and Lecanicillium cf. psalliotae, were inoculated directly on the scale insects or on insect infested plant material. We found that L. dimorphum and L. cf. psalliotae developed on plant material and on scale insects, making infection structures. B. bassiana was a bad colonizer of date palm leaves (Phoenix dactylifera L.) and did not parasite the scale insects.

Further description of Cruzia tentaculata (Rudolphi, 1819) Travassos, 1917 (Nematoda: Cruzidae) by light and scanning electron microscopy.

PubMed

Adnet, F A O; Anjos, D H S; Menezes-Oliveira, A; Lanfredi, R M

2009-04-01

Species of Cruzia are parasites of the large intestine of marsupials, reptiles, amphibians, and mammalians. Cruzia tentaculata specimens were collected from the large intestine of Didelphis marsupialis (Mammalia: Didelphidae) from Colombia (new geographical record) and from Brazil and analyzed by light and scanning electron microscopy. The morphology of males and females by light microscopy corroborated most of the previous description and the ultrastructure by scanning electron microscopy evidence: the topography of the cuticle, deirids, amphids, phasmids in both sexes, a pair of papillae near the vulva opening, and the number and location of male caudal papillae, adding new features for species identification only observed by this technique.

Transmission environmental scanning electron microscope with scintillation gaseous detection device.

PubMed

Danilatos, Gerasimos; Kollia, Mary; Dracopoulos, Vassileios

2015-03-01

A transmission environmental scanning electron microscope with use of a scintillation gaseous detection device has been implemented. This corresponds to a transmission scanning electron microscope but with addition of a gaseous environment acting both as environmental and detection medium. A commercial type of low vacuum machine has been employed together with appropriate modifications to the detection configuration. This involves controlled screening of various emitted signals in conjunction with a scintillation gaseous detection device already provided with the machine for regular surface imaging. Dark field and bright field imaging has been obtained along with other detection conditions. With a progressive series of modifications and tests, the theory and practice of a novel type of microscopy is briefly shown now ushering further significant improvements and developments in electron microscopy as a whole. Copyright © 2014 Elsevier B.V. All rights reserved.

Development of scanning electron and x-ray microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsumura, Tomokazu, E-mail: tomokzau.matsumura@etd.hpk.co.jp; Hirano, Tomohiko, E-mail: tomohiko.hirano@etd.hpk.co.jp; Suyama, Motohiro, E-mail: suyama@etd.hpk.co.jp

We have developed a new type of microscope possessing a unique feature of observing both scanning electron and X-ray images under one unit. Unlike former X-ray microscopes using SEM [1, 2], this scanning electron and X-ray (SELX) microscope has a sample in vacuum, thus it enables one to observe a surface structure of a sample by SEM mode, to search the region of interest, and to observe an X-ray image which transmits the region. For the X-ray observation, we have been focusing on the soft X-ray region from 280 eV to 3 keV to observe some bio samples and softmore » materials. The resolutions of SEM and X-ray modes are 50 nm and 100 nm, respectively, at the electron energy of 7 keV.« less

A compilation of cold cases using scanning electron microscopy at the University of Rhode Island

NASA Astrophysics Data System (ADS)

Platek, Michael J.; Gregory, Otto J.

2015-10-01

Scanning electron microscopy combined with microchemical analysis has evolved into one of the most widely used instruments in forensic science today. In particular, the environmental scanning electron microscope (SEM) in conjunction with energy dispersive spectroscopy (EDS), has created unique opportunities in forensic science in regard to the examination of trace evidence; i.e. the examination of evidence without altering the evidence with conductive coatings, thereby enabling criminalists to solve cases that were previously considered unsolvable. Two cold cases were solved at URI using a JEOL 5900 LV SEM in conjunction with EDS. A cold case murder and a cold missing person case will be presented from the viewpoint of the microscopist and will include sample preparation, as well as image and chemical analysis of the trace evidence using electron microscopy and optical microscopy.

Mechanical Characteristics of SiC Coating Layer in TRISO Fuel Particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

P. Hosemann; J. N. Martos; D. Frazer

2013-11-01

Tristructural isotropic (TRISO) particles are considered as advanced fuel forms for a variety of fission platforms. While these fuel structures have been tested and deployed in reactors, the mechanical properties of these structures as a function of production parameters need to be investigated in order to ensure their reliability during service. Nanoindentation techniques, indentation crack testing, and half sphere crush testing were utilized in order to evaluate the integrity of the SiC coating layer that is meant to prevent fission product release in the coated particle fuel form. The results are complimented by scanning electron microscopy (SEM) of the grainmore » structure that is subject to change as a function of processing parameters and can alter the mechanical properties such as hardness, elastic modulus, fracture toughness and fracture strength. Through utilization of these advanced techniques, subtle differences in mechanical properties that can be important for in-pile fuel performance can be distinguished and optimized in iteration with processing science of coated fuel particle production.« less

Methane-producing microbial community in a coal bed of the Illinois basin.

PubMed

Strapoc, Dariusz; Picardal, Flynn W; Turich, Courtney; Schaperdoth, Irene; Macalady, Jennifer L; Lipp, Julius S; Lin, Yu-Shih; Ertefai, Tobias F; Schubotz, Florence; Hinrichs, Kai-Uwe; Mastalerz, Maria; Schimmelmann, Arndt

2008-04-01

A series of molecular and geochemical studies were performed to study microbial, coal bed methane formation in the eastern Illinois Basin. Results suggest that organic matter is biodegraded to simple molecules, such as H(2) and CO(2), which fuel methanogenesis and the generation of large coal bed methane reserves. Small-subunit rRNA analysis of both the in situ microbial community and highly purified, methanogenic enrichments indicated that Methanocorpusculum is the dominant genus. Additionally, we characterized this methanogenic microorganism using scanning electron microscopy and distribution of intact polar cell membrane lipids. Phylogenetic studies of coal water samples helped us develop a model of methanogenic biodegradation of macromolecular coal and coal-derived oil by a complex microbial community. Based on enrichments, phylogenetic analyses, and calculated free energies at in situ subsurface conditions for relevant metabolisms (H(2)-utilizing methanogenesis, acetoclastic methanogenesis, and homoacetogenesis), H(2)-utilizing methanogenesis appears to be the dominant terminal process of biodegradation of coal organic matter at this location.

Alternative approach for cavitation damage study utilizing repetitive laser pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Fei; Wang, Jy-An John; Wang, Hong

2010-01-01

Cavitation is a common phenomenon in fluid systems that can lead to dramatic degradation of solid materials surface in contact with the cavitating media. Study of cavitation damage has great significance in many engineering fields. Current techniques for cavitation damage study either require large scale equipments or tend to introduce damages from other mechanisms. In this project, we utilized the cavitation phenomenon induced by laser optical breakdown and developed a prototype apparatus for cavitation damage study. In our approach, cavitation was generated by the repetitive pressure waves induced by high-power laser pulses. As proof of principal study, stainless steel andmore » aluminum samples were tested using the novel apparatus. Surface characterization via scanning electron microscopy revealed damages such as indentation and surface pitting, which were similar to those reported in literature using other state-of-the-art techniques. These preliminary results demonstrated the new device was capable of generating cavitation damages and could be used as an alternative method for cavitation damage study.« less

Transfer doping of single isolated nanodiamonds, studied by scanning probe microscopy techniques

NASA Astrophysics Data System (ADS)

Bolker, Asaf; Saguy, Cecile; Kalish, Rafi

2014-09-01

The transfer doping of diamond surfaces has been applied in various novel two-dimensional electronic devices. Its extension to nanodiamonds (ND) is essential for ND-based applications in many fields. In particular, understanding the influence of the crystallite size on transfer doping is desirable. Here, we report the results of a detailed study of the electronic energetic band structure of single, isolated transfer-doped nanodiamonds with nanometric resolution using a combination of scanning tunneling spectroscopy and Kelvin force microscopy measurements. The results show how the band gap, the valence band maximum, the electron affinity and the work function all depend on the ND’s size and nanoparticle surface properties. The present analysis, which combines information from both scanning tunneling spectroscopy and Kelvin force microscopy, should be applicable to any nanoparticle or surface that can be measured with scanning probe techniques.

Thickness determination of few-layer hexagonal boron nitride films by scanning electron microscopy and Auger electron spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sutter, P., E-mail: psutter@bnl.gov; Sutter, E.

2014-09-01

We assess scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) for thickness measurements on few-layer hexagonal boron nitride (h-BN), the layered dielectric of choice for integration with graphene and other two-dimensional materials. Observations on h-BN islands with large, atomically flat terraces show that the secondary electron intensity in SEM reflects monolayer height changes in films up to least 10 atomic layers thickness. From a quantitative analysis of AES data, the energy-dependent electron escape depth in h-BN films is deduced. The results show that AES is suitable for absolute thickness measurements of few-layer h-BN of 1 to 6 layers.

Design of a bioresorbable polymeric scaffold for osteoblast culture

NASA Astrophysics Data System (ADS)

Ditaranto, Vincent M., Jr.

Bioresorbable polymeric scaffolds were designed for the purpose of growing rat osteosarcoma cells (ROS 17/2.8) using the compression molding method. The material used in the construction of the scaffolds was a mixture of polycaprolactone (PCL), Hydroxyapatite (HA), Glycerin (GL) and salt (NaCl) for porosity. The concentration of the several materials utilized, was determined by volume. Past research at the University of Massachusetts Lowell (UML) has successfully utilized the compression molding method for the construction of scaffolds, but was unable to accomplish the goal of long term cell survival and complete cellular proliferation throughout a three dimensional scaffold. This research investigated various concentrations of the materials and molding temperatures used for the manufacture of scaffolds in order to improve the scaffold design and address those issues. The design of the scaffold using the compression molding process is detailed in the Method and Materials section of this thesis. The porogen (salt) used for porosity was suspected as a possible source of contamination causing cell apoptosis in past studies. This research addressed the issues for cell survival and proliferation throughout a three dimensional scaffold. The leaching of the salt was one major design modification. This research successfully used ultrasonic leaching in addition to the passive method. Prior to cell culture, the scaffolds were irradiated to 2.75 Mrad, with cobalt-60 gamma radionuclide. The tissue culture consisted of two trials: (1) cell culture in scaffolds cleaned with passive leaching; (2) cell culture with scaffolds cleaned with ultrasonic leaching. Cell survival and proliferation was accomplished only with the addition of ultrasonic leaching of the scaffolds. Analysis of the scaffolds included Scanning Electron Microscopy (SEM), Nikon light microscopy and x-ray mapping of the calcium, sodium and chloride ion distribution. The cells were analyzed by Environmental Scanning Electron Microscopy (ESEM) and Nikon light microscopy. The high magnification of ESEM up to 60,000 x revealed an unexpected discovery. The osteoblasts appeared to be remodeling the PCL scaffold shown in the last two figures of this research.

Health information exchange associated with improved emergency department care through faster accessing of patient information from outside organizations.

PubMed

Everson, Jordan; Kocher, Keith E; Adler-Milstein, Julia

2017-04-01

To assess whether electronic health information exchange (HIE) is associated with improved emergency department (ED) care processes and utilization through more timely clinician viewing of information from outside organizations. Our data included 2163 patients seen in the ED of a large academic medical center for whom clinicians requested and viewed outside information from February 14, 2014, to February 13, 2015. Outside information requests w.ere fulfilled via HIE (Epic's Care Everywhere) or fax/scan to the electronic health record (EHR). We used EHR audit data to capture the time between the information request and when a clinician accessed the data. We assessed whether the relationship between method of information return and ED outcomes (length of visit, odds of imaging [computed tomography (CT), magnetic resonance imaging (MRI), radiographs] and hospitalization, and total charges) was mediated by request-to-access time, controlling for patient demographics, case mix, and acuity. In multivariate analysis, there was no direct association between return of information via HIE vs fax/scan and ED outcomes. HIE was associated with faster outside information access (58.5 minutes on average), and faster access was associated with changes in ED care. For each 1-hour reduction in access time, visit length was 52.9 minutes shorter, the likelihood of imaging was lower (by 2.5, 1.6, and 2.4 percentage points for CT, MRI, and radiographs, respectively), the likelihood of admission was 2.4 percentage points lower, and average charges were $1187 lower ( P  ≤ .001 for all). The relationship between HIE and improved care processes and reduced utilization in the ED is mediated by faster accessing of information from outside organizations. © The Author 2016. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Using Medical Claims for Policy Effectiveness Surveillance: Reimbursement and Utilization of Abdomen/Pelvis Computed Tomography Scans.

PubMed

Horný, Michal; Morgan, Jake R; Merker, Vanessa L

2015-12-01

To quantify changes in private insurance payments for and utilization of abdominal/pelvic computed tomography scans (CTs) after 2011 changes in CPT coding and Medicare reimbursement rates, which were designed to reduce costs stemming from misvalued procedures. TruvenHealth Analytics MarketScan Commercial Claims and Encounters database. We used difference-in-differences models to compare combined CTs of the abdomen/pelvis to CTs of the abdomen or pelvis only. Our main outcomes were inflation-adjusted log payments per procedure, daily utilization rates, and total annual payments. Claims data were extracted for all abdominal/pelvic CTs performed in 2009-2011 within noncapitated, employer-sponsored private plans. Adjusted payments per combined CTs of the abdomen/pelvis dropped by 23.8 percent (p < .0001), and their adjusted daily utilization rate accelerated by 0.36 percent (p = .034) per month after January 2011. Utilization rate of abdominal-only or pelvic-only CTs dropped by 5.0 percent (p < .0001). Total annual payments for combined CTs of the abdomen/pelvis decreased in 2011 despite the increased utilization. Private insurance payments for combined CTs of the abdomen/pelvis declined and utilization accelerated significantly after 2011 policy changes. While growth in total annual payments was contained in 2011, it may not be sustained if 2011 utilization trends persist. © Health Research and Educational Trust.

Provider Distribution Changes in Dual-Energy X-Ray Absorptiometry in the Medicare Population Over the Past Decade.

PubMed

Intenzo, Charles M; Parker, Laurence; Levin, David C; Kim, Sung M; Rao, Vijay M

2016-01-01

Both radiologists as well as nonimaging physicians perform dual-energy X-ray absorptiometry (DXA) imaging in the United States. This study aims to compare provider distribution between these physician groups on the Medicare population, which is the predominant age group of patients evaluated by this imaging procedure. Using the 2 relevant Current Procedural Terminology, Fourth Edition codes for DXA scans, source data were obtained from the CMS Physician Supplier Procedure Summary Master Files from 2003 through 2013. DXA scan procedure volumes for radiologists and nonradiologists on Medicare patients were tabulated. Utilization rates were calculated. From 2003 to 2013, the total number of DXA scans performed on Medicare patients decreased by 2%. However, over the same period, the number of scans performed by radiologists had increased by 25% over nonimaging specialists, whose utilization had declined by approximately the same amount. From 2003 to 2013, the rate of utilization of DXA scans in the Medicare fee-for-service population declined somewhat. However, radiologists continue to gain market share from other specialists and now predominate in this type of imaging by a substantial margin. Copyright © 2016 International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.

75 FR 32860 - Regulatory Guidance Concerning the Preparation of Drivers' Record of Duty Status To Document...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-10

... motor carrier of a scanned image of the original record; the driver would retain the original while the carrier maintains the electronic scanned electronic image along with any supporting documents. [[Page... plans to implement a new approach for receiving and processing RODS. Its drivers would complete their...

77 FR 16158 - Current Good Manufacturing Practice in Manufacturing, Processing, Packing, or Holding of Drugs...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-20

... ``cut'' from a sheet or roll of labels--is used. Persistent problems with drug product mislabeling and... believe that development and use of advanced code scanning equipment has made many current electronic... and other advanced scanning techniques have made current electronic systems reliable to the 100...

Scanning electron microscope view of iron crystal growing on pyroxene crystal

NASA Technical Reports Server (NTRS)

1972-01-01

A scanning electron microscope photograph of a four-micron size iron crystal growing on a pyroxene crystal (calcium-magnesium-iron silicate) from the Apollo 15 Hadley-Apennino lunar landing site. The well developed crystal faces indicate that the crystal was formed from a hot vapor as the rock was cooling.

Low temperature–scanning electron microscopy to evaluate morphology and predation of Scolothrips sexmaculatus Pergande (Thysanoptera: Thripidae) against spider mites (Acari: Tetranychidae: Tetranychus species)

USDA-ARS?s Scientific Manuscript database

This paper evaluates the potential usefulness of low temperature-scanning electron microscopy (LT-SEM) to evaluate morphology and predation behavior of the six-spotted thrips (Scolothrips sexmaculatus Pergande) against the two-spotted spider mite (Tetranychus urticae (Koch)). Morphological features...

Arc-melting preparation of single crystal LaB.sub.6 cathodes

DOEpatents

Gibson, Edwin D.; Verhoeven, John D.

1977-06-21

A method for preparing single crystals of lanthanum hexaboride (LaB.sub.6) by arc melting a rod of compacted LaB.sub.6 powder. The method is especially suitable for preparing single crystal LaB.sub.6 cathodes for use in scanning electron microscopes (SEM) and scanning transmission electron microscopes (STEM).

Monte Carlo simulation for scanning technique with scattering foil free electron beam: A proof of concept study

PubMed Central

Sung, Wonmo; Park, Jong In; Kim, Jung-in; Carlson, Joel; Ye, Sung-Joon

2017-01-01

This study investigated the potential of a newly proposed scattering foil free (SFF) electron beam scanning technique for the treatment of skin cancer on the irregular patient surfaces using Monte Carlo (MC) simulation. After benchmarking of the MC simulations, we removed the scattering foil to generate SFF electron beams. Cylindrical and spherical phantoms with 1 cm boluses were generated and the target volume was defined from the surface to 5 mm depth. The SFF scanning technique with 6 MeV electrons was simulated using those phantoms. For comparison, volumetric modulated arc therapy (VMAT) plans were also generated with two full arcs and 6 MV photon beams. When the scanning resolution resulted in a larger separation between beams than the field size, the plan qualities were worsened. In the cylindrical phantom with a radius of 10 cm, the conformity indices, homogeneity indices and body mean doses of the SFF plans (scanning resolution = 1°) vs. VMAT plans were 1.04 vs. 1.54, 1.10 vs. 1.12 and 5 Gy vs. 14 Gy, respectively. Those of the spherical phantom were 1.04 vs. 1.83, 1.08 vs. 1.09 and 7 Gy vs. 26 Gy, respectively. The proposed SFF plans showed superior dose distributions compared to the VMAT plans. PMID:28493940

Monte Carlo simulation for scanning technique with scattering foil free electron beam: A proof of concept study.

PubMed

Sung, Wonmo; Park, Jong In; Kim, Jung-In; Carlson, Joel; Ye, Sung-Joon; Park, Jong Min

2017-01-01

This study investigated the potential of a newly proposed scattering foil free (SFF) electron beam scanning technique for the treatment of skin cancer on the irregular patient surfaces using Monte Carlo (MC) simulation. After benchmarking of the MC simulations, we removed the scattering foil to generate SFF electron beams. Cylindrical and spherical phantoms with 1 cm boluses were generated and the target volume was defined from the surface to 5 mm depth. The SFF scanning technique with 6 MeV electrons was simulated using those phantoms. For comparison, volumetric modulated arc therapy (VMAT) plans were also generated with two full arcs and 6 MV photon beams. When the scanning resolution resulted in a larger separation between beams than the field size, the plan qualities were worsened. In the cylindrical phantom with a radius of 10 cm, the conformity indices, homogeneity indices and body mean doses of the SFF plans (scanning resolution = 1°) vs. VMAT plans were 1.04 vs. 1.54, 1.10 vs. 1.12 and 5 Gy vs. 14 Gy, respectively. Those of the spherical phantom were 1.04 vs. 1.83, 1.08 vs. 1.09 and 7 Gy vs. 26 Gy, respectively. The proposed SFF plans showed superior dose distributions compared to the VMAT plans.

Scanning system for angle-resolved low-coherence interferometry.

PubMed

Steelman, Zachary A; Ho, Derek; Chu, Kengyeh K; Wax, Adam

2017-11-15

Angle-resolved low-coherence interferometry (a/LCI) detects precancer by enabling depth-resolved measurements of nuclear morphology in vivo. A significant limitation of a/LCI is the point-probe nature of the method, sampling <0.5  mm 2 before probe relocation is necessary. In this work, we demonstrate a scanning method capable of assessing an area >100  mm 2 without repositioning. By utilizing a reflection-only three-optic rotator prism and a two-axis scanning mirror, we demonstrate radial scans of a sample with a linear range of 12 mm and a full rotational range of 180°. Use of this design will improve the diagnostic utility of a/LCI for wide-area screening of tissue health.

A scanning system for angle-resolved low-coherence interferometry

PubMed Central

Steelman, Zachary A.; Ho, Derek; Chu, Kengyeh K.; Wax, Adam

2018-01-01

Angle-resolved low-coherence interferometry (a/LCI) detects precancer by enabling depth-resolved measurements of nuclear morphology in vivo. A significant limitation of a/LCI is the point-probe nature of the method, sampling <0.5 mm2 before probe relocation is necessary. In this work, we demonstrate a scanning method capable of assessing an area >100 mm2 without repositioning. By utilizing a reflection-only three-optic rotator (ROTOR) prism and two-axis scanning mirror, we demonstrate radial scans of a sample with a linear range of 12 mm and a full rotational range of 180°. Use of this design will improve the diagnostic utility of a/LCI for wide-area screening of tissue health. PMID:29140317

Clinical utility of MRI and SPECT in the diagnosis of cognitive impairment referred to memory clinic.

PubMed

Guinane, John; Ng, Boon Lung

2018-05-01

ABSTRACTBackground:Despite of their limited availability and potential for significant variation between and within each modality, this is the first study to prospectively measure the clinical utility of MRI and/or SPECT brain scanning in addition to the routine diagnostic workup of patients presenting to memory clinic. A single center study was conducted over a convenience of 12-month sampling period. For each patient referred for MRI and/or SPECT scanning, the primary geriatrician or psychogeriatrician was asked to assign an initial diagnosis. The initial diagnosis was then compared with the final consensus diagnosis after any scans or neuropsychology testing had been completed. During the 12-month study period, 66 patients (26%) were referred for scans out of a total of 253 patients included in the study. There were 16/44 (36%) positive MRI outcomes and 13/35 (37%) positive SPECT outcomes. The diagnosis changed consistent with the MRI scan findings in 11/44 (25%) and changed consistent with the SPECT scan findings in 9/35 (26%). Potentially reversible pathology was identified in a single patient, 1/50 (2%), via an MRI scan that suggested normal pressure hydrocephalus. The number needed to test for one positive outcome was 3.8 (95% CI 2.0-23.3), 6.0 (95% CI NA), and 1.7 (95% CI 1.3-2.5) for MRI only, SPECT only, and MRI and SPECT together, respectively. The clinical utility of MRI and/or SPECT scanning in this study may be broadly superior to the available international evidence, and further research is needed to identify predictors of positive scan outcomes.

Fabrication and properties of nanoscale multiferroic heterostructures for application in magneto-electric random access memory (MERAM) devices

NASA Astrophysics Data System (ADS)

Kim, Gunwoo

Magnetoelectric random access memory (MERAM) has emerged as a promising new class of non-volatile solid-state memory device. It offers nondestructive reading along with low power consumption during the write operation. A common implementation of MERAM involves use of multiferroic tunneling junctions (MFTJs), which besides offering non-volatility are both electrically and magnetically tunable. Fundamentally, a MFTJ consists of a heterostructure of an ultrathin multiferroic or ferroelectric material as the active tunneling barrier sandwiched between ferromagnetic electrodes. Thereby, the MFTJ exhibits both tunnel electroresistance (TER) and tunnel magnetoresistance (TMR) effects with application of an electric and magnetic field, respectively. In this thesis work, we have developed two-dimensional (2D) thin-film multiferroic heterostructure METJ prototypes consisting of ultrathin ferroelectric BaTiO3 (BTO) layer and a conducting ferromagnetic La0.67Sr 0.33MnO3 (LSMO) electrode. The heteroepitaxial films are grown using the pulsed laser deposition (PLD) technique. This oxide heterostructure offers the opportunity to study the nano-scale details of the tunnel electroresistance (TER) effect using scanning probe microscopy techniques. We performed the measurements using the MFP-3D (Asylum Research) scanning probe microscope. The ultrathin BTO films (1.2-2.0 nm) grown on LSMO electrodes display both ferro- and piezo-electric properties and exhibit large tunnel resistance effect. We have explored the growth and properties of one-dimensional (1D) heterostructures, referred to as multiferoric nanowire (NW) heterostructures. The ferromagnetic/ferroelectric composite heterostructures are grown as sheath layers using PLD on lattice-matched template NWs, e.g. MgO, that are deposited by chemical vapor deposition utilizing the vapor-liquid-solid (VLS) mechanism. The one-dimensional geometry can substantially overcome the clamping effect of the substrate present in two-dimensional structures because of the reduced volume of the template. This leads to minimum constraint of displacements at the interface and thereby significantly enhances the magnetoelectric (ME) effect. We characterized the nanostructures using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results of our studies utilizing multiferroic 2-D thin films and 1-D NW architectures clearly demonstrate the potential of these heterostructures for future device applications, such as in MERAM, data storage, magneto-electric field sensors, etc.

Molecular tips for scanning tunneling microscopy: intermolecular electron tunneling for single-molecule recognition and electronics.

PubMed

Nishino, Tomoaki

2014-01-01

This paper reviews the development of molecular tips for scanning tunneling microscopy (STM). Molecular tips offer many advantages: first is their ability to perform chemically selective imaging because of chemical interactions between the sample and the molecular tip, thus improving a major drawback of conventional STM. Rational design of the molecular tip allows sophisticated chemical recognition; e.g., chiral recognition and selective visualization of atomic defects in carbon nanotubes. Another advantage is that they provide a unique method to quantify electron transfer between single molecules. Understanding such electron transfer is mandatory for the realization of molecular electronics.

Two-dimensional mapping of polarizations of rhombohedral nanostructures in the orthorhombic phase of KNbO3 by the combined use of scanning transmission electron microscopy and convergent-beam electron diffraction

NASA Astrophysics Data System (ADS)

Tsuda, Kenji; Tanaka, Michiyoshi

2015-08-01

Rhombohedral nanostructures previously found in the orthorhombic phase of KNbO3, by convergent-beam electron diffraction [Tsuda et al., Appl. Phys. Lett. 102, 051913 (2013)], have been investigated by the combined use of scanning transmission electron microscopy and convergent-beam electron diffraction. Two-dimensional distributions of the rhombohedral nanostructures, or nanometer-scale spatial fluctuations of polarization clusters, have been successfully visualized. The correlation length of the observed spatial fluctuations of local polarizations is related to the cpc/apc ratio and the transition entropy.

A scanning electron microscopic study of 34 cases of acute granulocytic, myelomonocytic, monoblastic and histiocytic leukemia.

PubMed

Polliack, A; McKenzie, S; Gee, T; Lampen, N; de Harven, E; Clarkson, B D

1975-09-01

This report describes the surface architecture of leukemic cells, as seen by scanning electron microscopy in 34 patients with acute nonlymphoblastic leukemia. Six patients with myeloblastic, 4 with promyelocytic, 10 with myelomonocytic, 8 with monocytic, 4 with histiocytic and 2 with undifferentiated leukemia were studied. Under the scanning electron microscope most leukemia histiocytes and monocytes appeared similar and were characterized by the presence of large, well developed broad-based ruffled membranes or prominent raised ridge-like profiles, resembling ithis respect normal monocytes. Most cells from patients with acute promyelocytic or myeloblastic leukemia exhibited narrower ridge-like profiles whereas some showed ruffles or microvilli. Patients with myelomonocytic leukemia showed mixed populations of cells with ridge-like profiles and ruffled membranes whereas cells from two patients with undifferentiated leukemia had smooth surfaces, similar to those encountered in cells from patients with acute lymphoblastic leukemia. It appears that nonlymphoblastic and lymphoblastic leukemia cells (particularly histiocytes and monocytes) can frequently be distinquished on the basis of their surface architecture. The surface features of leukemic histiocytes and monocytes are similar, suggesting that they may belong to the same cell series. The monocytes seem to have characteristic surface features recognizable with the scanning electron microscope and differ from most cells from patients with acute granulocytic leukemia. Although overlap of surface features and misidentification can occur, scanning electron microscopy is a useful adjunct to other modes of microscopy in the study and diagnosis of acute leukemia.

Imaging electron motion in graphene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhandari, Sagar; Westervelt, Robert M.

A cooled scanning probe microscope (SPM) is an ideal tool to image electronic motion in graphene: the SPM tip acts as a scanning gate, which interacts with the electron gas below. We introduce the technique using our group's previous work on imaging electron flow from a quantum point contact in a GaAs 2DEG and tuning an InAs quantum dot in an InAs/InP nanowire. Carriers in graphene have very different characteristics: electrons and holes travel at a constant speed with no bandgap, and they pass through potential barriers via Klein tunneling. In this paper, we review the extension of SPM imagingmore » techniques to graphene. We image the cyclotron orbits passing between two narrow contacts in a single-atomic-layer graphene device in a perpendicular magnetic field. Magnetic focusing produces a peak in transmission between the contacts when the cyclotron diameter is equal to the contact spacing. The charged SPM tip deflects electrons passing from one contact to the other, changing the transmission when it interrupts the flow. By displaying the change in transmission as the tip is raster scanned above the sample, an image of flow is obtained. In addition, we have developed a complementary technique to image electronic charge using a cooled scanning capacitance microscope (SCM) that uses a sensitive charge preamplifier near the SPM tip to achieve a charge noise level 0.13 e Hz -1/2 with high spatial resolution 100 nm. The cooled SPM and SCM can be used to probe the motion of electrons on the nanoscale in graphene devices.« less

Imaging electron motion in graphene

DOE PAGES

Bhandari, Sagar; Westervelt, Robert M.

2017-01-05

A cooled scanning probe microscope (SPM) is an ideal tool to image electronic motion in graphene: the SPM tip acts as a scanning gate, which interacts with the electron gas below. We introduce the technique using our group's previous work on imaging electron flow from a quantum point contact in a GaAs 2DEG and tuning an InAs quantum dot in an InAs/InP nanowire. Carriers in graphene have very different characteristics: electrons and holes travel at a constant speed with no bandgap, and they pass through potential barriers via Klein tunneling. In this paper, we review the extension of SPM imagingmore » techniques to graphene. We image the cyclotron orbits passing between two narrow contacts in a single-atomic-layer graphene device in a perpendicular magnetic field. Magnetic focusing produces a peak in transmission between the contacts when the cyclotron diameter is equal to the contact spacing. The charged SPM tip deflects electrons passing from one contact to the other, changing the transmission when it interrupts the flow. By displaying the change in transmission as the tip is raster scanned above the sample, an image of flow is obtained. In addition, we have developed a complementary technique to image electronic charge using a cooled scanning capacitance microscope (SCM) that uses a sensitive charge preamplifier near the SPM tip to achieve a charge noise level 0.13 e Hz -1/2 with high spatial resolution 100 nm. The cooled SPM and SCM can be used to probe the motion of electrons on the nanoscale in graphene devices.« less

Atmospheric pressure scanning transmission electron microscopy.

PubMed

de Jonge, Niels; Bigelow, Wilbur C; Veith, Gabriel M

2010-03-10

Scanning transmission electron microscope (STEM) images of gold nanoparticles at atmospheric pressure have been recorded through a 0.36 mm thick mixture of CO, O2, and He. This was accomplished using a reaction cell consisting of two electron-transparent silicon nitride membranes. Gold nanoparticles of a full width at half-maximum diameter of 1.0 nm were visible above the background noise, and the achieved edge resolution was 0.4 nm in accordance with calculations of the beam broadening.

Atom Chips on Direct Bonded Copper Substrates (Postprint)

DTIC Science & Technology

2012-01-19

joining of a thin sheet of pure copper to a ceramic substrate14 and is commonly used in power electronics due to its high current handling and heat...Squires et al. Rev. Sci. Instrum. 82, 023101 (2011) FIG. 1. A scanning electron micrograph of the top view of test chip A. the photolithographically...the etching pro- cesses and masking methods were quantified using a scanning electron microscope. Two test chips (A and B) are presented below and are

Epitaxial Growth and Electronic Structure of Half Heuslers Co1-xNixTiSb (001), Ni1-xCoxTiSn, and PtLuSb

DTIC Science & Technology

2016-01-09

studied in detail using scanning tunneling microscopy and angle resolved photoemission. For the doping levels achieved in cobalt titanium antimony, the...angle resolved photoemission. For the doping levels achieved in cobalt titanium antimony, the electron mobility at room temperature was comparable...scanning tunneling microscopy and angle resolved photoemission. For the doping levels achieved in cobalt titanium antimony, the electron mobility at room

Sparsity-Based Super Resolution for SEM Images.

PubMed

Tsiper, Shahar; Dicker, Or; Kaizerman, Idan; Zohar, Zeev; Segev, Mordechai; Eldar, Yonina C

2017-09-13

The scanning electron microscope (SEM) is an electron microscope that produces an image of a sample by scanning it with a focused beam of electrons. The electrons interact with the atoms in the sample, which emit secondary electrons that contain information about the surface topography and composition. The sample is scanned by the electron beam point by point, until an image of the surface is formed. Since its invention in 1942, the capabilities of SEMs have become paramount in the discovery and understanding of the nanometer world, and today it is extensively used for both research and in industry. In principle, SEMs can achieve resolution better than one nanometer. However, for many applications, working at subnanometer resolution implies an exceedingly large number of scanning points. For exactly this reason, the SEM diagnostics of microelectronic chips is performed either at high resolution (HR) over a small area or at low resolution (LR) while capturing a larger portion of the chip. Here, we employ sparse coding and dictionary learning to algorithmically enhance low-resolution SEM images of microelectronic chips-up to the level of the HR images acquired by slow SEM scans, while considerably reducing the noise. Our methodology consists of two steps: an offline stage of learning a joint dictionary from a sequence of LR and HR images of the same region in the chip, followed by a fast-online super-resolution step where the resolution of a new LR image is enhanced. We provide several examples with typical chips used in the microelectronics industry, as well as a statistical study on arbitrary images with characteristic structural features. Conceptually, our method works well when the images have similar characteristics, as microelectronics chips do. This work demonstrates that employing sparsity concepts can greatly improve the performance of SEM, thereby considerably increasing the scanning throughput without compromising on analysis quality and resolution.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strelcov, Evgheni; Cothren, Joshua E.; Leonard, Donovan N.

Progress in rational engineering of Li-ion batteries requires better understanding of the electrochemical processes and accompanying transformations in the electrode materials on multiple length scales. In spite of recent progress in utilizing transmission electron microscopy (TEM) to analyze these materials, in situ scanning electron microscopy (SEM) was mostly overlooked as a powerful tool that allows probing these phenomena on the nano and mesoscale. In this paper, we report on in situ SEM study of lithiation in a V 2O 5-based single-nanobelt battery with ionic liquid electrolyte. Coupled with cyclic voltammetry measurements, in situ SEM revealed the peculiarities of subsurface intercalation,more » formation of solid-electrolyte interface (SEI) and electromigration of liquid. We observed that single-crystalline vanadia nanobelts do not undergo large-scale amorphization or fracture during electrochemical cycling, but rather transform topochemically with only a slight shape distortion. Lastly, the SEI layer seems to have significant influence on the lithium ion diffusion and overall capacity of the single-nanobelt battery.« less

Development of graphite/copper composites utilizing engineered interfaces. M.S. Thesis Final Report

NASA Technical Reports Server (NTRS)

Devincent, Sandra M.

1991-01-01

In situ measurements of graphite/copper alloy contact angles were made using the sessile drop method. The interfacial energy values obtained from these measurements were then applied to a model for the fiber matrix interfacial debonding phenomenon found in graphite/copper composites. The formation obtained from the sessile drop tests led to the development of a copper alloy that suitably wets graphite. Characterization of graphite/copper alloy interfaces subjected to elevated temperatures was conducted using Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Auger Electron Spectroscopy, and X Ray Diffraction analyses. These analyses indicated that during sessile drop tests conducted at 1130 C for 1 hour, copper alloys containing greater than 0.98 at pct chromium form continuous reaction layers of approx. 10 microns in thickness. The reaction layers are adherent to the graphite surface. The copper wets the reaction layer to form a contact angle of 60 deg or less. X ray diffraction results indicate that the reaction layer is Cr3C2.

Polyaniline modified graphene and carbon nanotube composite electrode for asymmetric supercapacitors of high energy density

NASA Astrophysics Data System (ADS)

Cheng, Qian; Tang, Jie; Shinya, Norio; Qin, Lu-Chang

2013-11-01

Graphene and single-walled carbon nanotube (CNT) composites are explored as the electrodes for supercapacitors by coating polyaniline (PANI) nano-cones onto the graphene/CNT composite to obtain graphene/CNT-PANI composite electrode. The graphene/CNT-PANI electrode is assembled with a graphene/CNT electrode into an asymmetric pseudocapacitor and a highest energy density of 188 Wh kg-1 and maximum power density of 200 kW kg-1 are achieved. The structure and morphology of the graphene/CNT composite and the PANI nano-cone coatings are characterized by both scanning electron microscopy and transmission electron microscopy. The excellent performance of the assembled supercapacitors is also discussed and it is attributed to (i) effective utilization of the large surface area of the three-dimensional network structure of graphene-based composite, (ii) the presence of CNT in the composite preventing graphene from re-stacking, and (ii) uniform and vertically aligned PANI coating on graphene offering increased electrical conductivity.

The functionalization of limonite to prepare NZVI and its application in decomposition of p-nitrophenol

NASA Astrophysics Data System (ADS)

Liu, Haibo; Chen, Tianhu; Xie, Qiaoqin; Zou, Xuehua; Chen, Chen; Frost, Ray L.

2015-09-01

Nano zero valent iron (NZVI) was prepared by reducing natural limonite using hydrogen. X-ray fluorescence, thermogravimetry, X-ray diffraction, transmission electron microscope, temperature programmed reduction (TPR), field emission scanning electron microscope/energy disperse spectroscopy (FESEM/EDS) were utilized to characterize the natural limonite and reduced limonite. The ratios of Fe:O before and after reducing was determined using EDS. The reactivity of the NZVI was assessed by decomposition of p-nitrophenol ( p-NP) and was compared with commercial iron powder. In this study, the results of TPR and FESEM/EDS indicated that NZVI can be prepared by reducing natural limonite using hydrogen. Most importantly, this NZVI was proved to have a good performance on decomposition of p-NP and the process of p-NP decomposition agreed well with the pseudo-first-order kinetic model. The reactivity of this NZVI for decomposition of p-NP was greatly superior to that of commercial iron powder.

Formation of Supported Graphene Oxide: Evidence for Enolate Species.

PubMed

Novotny, Zbynek; Nguyen, Manh-Thuong; Netzer, Falko P; Glezakou, Vassiliki-Alexandra; Rousseau, Roger; Dohnálek, Zdenek

2018-04-18

Graphene oxides are promising materials for novel electronic devices or anchoring of the active sites for catalytic applications. Here we focus on understanding the atomic oxygen (AO) binding and mobility on different regions of graphene (Gr) on Ru(0001). Differences in the Gr/Ru lattices result in the superstructure, which offers an array of distinct adsorption sites. We employ scanning tunneling microscopy and density functional theory to map out the chemical identity and stability of prepared AO functionalities in different Gr regions. The AO diffusion is utilized to establish that in the regions that are close to the metal substrate the terminally bonded enolate groups are strongly preferred over bridge-bonded epoxy groups. No oxygen species are observed on the graphene regions that are far from the underlying Ru, indicating their low relative stability. This study provides a clear fundamental basis for understanding the local structural, electronic factors and C-Ru bond strengthening/weakening processes that affect the stability of enolate and epoxy species.

Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors.

PubMed

He, Tao; Wu, Yanfei; D'Avino, Gabriele; Schmidt, Elliot; Stolte, Matthias; Cornil, Jérôme; Beljonne, David; Ruden, P Paul; Würthner, Frank; Frisbie, C Daniel

2018-05-30

Understanding relationships between microstructure and electrical transport is an important goal for the materials science of organic semiconductors. Combining high-resolution surface potential mapping by scanning Kelvin probe microscopy (SKPM) with systematic field effect transport measurements, we show that step edges can trap electrons on the surfaces of single crystal organic semiconductors. n-type organic semiconductor crystals exhibiting positive step edge surface potentials display threshold voltages that increase and carrier mobilities that decrease with increasing step density, characteristic of trapping, whereas crystals that do not have positive step edge surface potentials do not have strongly step density dependent transport. A device model and microelectrostatics calculations suggest that trapping can be intrinsic to step edges for crystals of molecules with polar substituents. The results provide a unique example of a specific microstructure-charge trapping relationship and highlight the utility of surface potential imaging in combination with transport measurements as a productive strategy for uncovering microscopic structure-property relationships in organic semiconductors.

Electron petrography of silica polymorphs associated with pseudotachylite, Vredefort structure, South Africa

NASA Technical Reports Server (NTRS)

White, J. C.

1992-01-01

High-pressure silica polymorphs (coesite and stishovite) were described from the Vredefort structure in association with pseudotachylite veinlets. In addition to the fundamental significance of the polymorphs to genetic interpretations of the structure, it was additionally argued that the type of pseudotachylite with which they occur forms during the compressional phase of the shock process, while the larger, classic pseudotachylite occurrences are barren of polymorphs and formed during passage of the rarefaction wave. This identification of temporal relationships among transient shock features at a regional scale is similar to observations from the Manicouagan structure, Quebec, where texturally distinct diaplectic plagioclase glasses formed during both compressional and decompressional phases of the shock process. The clarification of such relationships impinges directly on interpretations of natural shock processes and the identification of high probability targets for polymorph searches. Detailed analytical scanning (SEM) and transmission electron microscopy (TEM) were utilized to further establish the nature of both the pseudotachylite and the silica polymorph occurrences in the Vredefort rocks. The results of this investigation are discussed.

Optical and structural properties of cobalt-permalloy slanted columnar heterostructure thin films

NASA Astrophysics Data System (ADS)

Sekora, Derek; Briley, Chad; Schubert, Mathias; Schubert, Eva

2017-11-01

Optical and structural properties of sequential Co-column-NiFe-column slanted columnar heterostructure thin films with an Al2O3 passivation coating are reported. Electron-beam evaporated glancing angle deposition is utilized to deposit the sequential multiple-material slanted columnar heterostructure thin films. Mueller matrix generalized spectroscopic ellipsometry data is analyzed with a best-match model approach employing the anisotropic Bruggeman effective medium approximation formalism to determine bulk-like and anisotropic optical and structural properties of the individual Co and NiFe slanted columnar material sub-layers. Scanning electron microscopy is applied to image the Co-NiFe sequential growth properties and to verify the results of the ellipsometric analysis. Comparisons to single-material slanted columnar thin films and optically bulk solid thin films are presented and discussed. We find that the optical and structural properties of each material sub-layer of the sequential slanted columnar heterostructure film are distinct from each other and resemble those of their respective single-material counterparts.

Detailed Investigation of Core-Shell Precipitates in a Cu-Containing High Entropy Alloy

NASA Astrophysics Data System (ADS)

Alam, T.; Gwalani, B.; Viswanathan, G.; Fraser, H.; Banerjee, R.

2018-05-01

Due to the competing influences of configurational entropy and enthalpy of mixing, in recent years, secondary (including intermetallic) phases have been reported in many high entropy alloy (HEA) systems. These secondary phases offer great potential in terms of strengthening the HEA beyond the solid solution strengthening effects, and as such are of great interest in regards to alloy design for engineering applications. The present research investigates novel nano-scale core-shell precipitates forming within the disordered bcc matrix phase of an Al2CrCuFeNi2 HEA, utilizing complementary high-resolution microscopy techniques of atom probe tomography (APT) and transmission electron microscopy (TEM). The size, morphology, and local chemistry of these core-shell precipitates was measured by APT, and the composition was further corroborated by high-resolution scanning transmission electron microscopy-energy dispersive spectroscopy in an aberration-corrected TEM. Furthermore, high-resolution TEM imaging of the core-shell structure indicates that the Cu-rich core exhibits a bcc crystal structure.

Study of the optical properties of CuAlS2 thin films prepared by two methods

NASA Astrophysics Data System (ADS)

Ahmad, S. M.

2017-04-01

CuAlS2 thin films were successfully deposited on glass substrates using two methods: chemical spray pyrolysis (CSP) and chemical bath deposition (CBD). It was confirmed from the X-ray diffraction (XRD) analysis that CSP films exhibited a polycrystalline nature while amorphous nature was diagnosed for CBD films. Also XRD analysis was utilized to compute grain size, strain and dislocation density. Surface morphology was characterized using scanning electron microscope and photomicroscope images. The optical absorption measurement revealed that the direct allowed electronic transition with band gaps 2.8 eV and 3.0 eV for CBD and CSP methods, respectively. The optical constants, such as extinction coefficient ( k), refractive index ( n), real and imaginary dielectric constants ( ɛ 1, ɛ 2) were discussed. The photoluminescence (PL) spectra of CuAlS2 thin films appeared as a single peak for each of them, and this is attributed to band-to-band transition.

Atom-Dependent Edge-Enhanced Second-Harmonic Generation on MoS2 Monolayers.

PubMed

Lin, Kuang-I; Ho, Yen-Hung; Liu, Shu-Bai; Ciou, Jian-Jhih; Huang, Bo-Ting; Chen, Christopher; Chang, Han-Ching; Tu, Chien-Liang; Chen, Chang-Hsiao

2018-02-14

Edge morphology and lattice orientation of single-crystal molybdenum disulfide (MoS 2 ) monolayers, a transition metal dichalcogenide (TMD), possessing a triangular shape with different edges grown by chemical vapor deposition are characterized by atomic force microscopy and transmission electron microscopy. Multiphoton laser scanning microscopy is utilized to study one-dimensional atomic edges of MoS 2 monolayers with localized midgap electronic states, which result in greatly enhanced optical second-harmonic generation (SHG). Microscopic S-zigzag edge and S-Mo Klein edge (bare Mo atoms protruding from a S-zigzag edge) terminations and the edge-atom dependent resonance energies can therefore be deduced based on SHG images. Theoretical calculations based on density functional theory clearly explain the lower energy of the S-zigzag edge states compared to the corresponding S-Mo Klein edge states. Characterization of the atomic-scale variation of edge-enhanced SHG is a step forward in this full-optical and high-yield technique of atomic-layer TMDs.

Nano-textured high sensitivity ion sensitive field effect transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hajmirzaheydarali, M.; Sadeghipari, M.; Akbari, M.

2016-02-07

Nano-textured gate engineered ion sensitive field effect transistors (ISFETs), suitable for high sensitivity pH sensors, have been realized. Utilizing a mask-less deep reactive ion etching results in ultra-fine poly-Si features on the gate of ISFET devices where spacing of the order of 10 nm and less is achieved. Incorporation of these nano-sized features on the gate is responsible for high sensitivities up to 400 mV/pH in contrast to conventional planar structures. The fabrication process for this transistor is inexpensive, and it is fully compatible with standard complementary metal oxide semiconductor fabrication procedure. A theoretical modeling has also been presented to predict themore » extension of the diffuse layer into the electrolyte solution for highly featured structures and to correlate this extension with the high sensitivity of the device. The observed ultra-fine features by means of scanning electron microscopy and transmission electron microscopy tools corroborate the theoretical prediction.« less

Scanning electron microscopic appearance of rat otocyst of the twelfth postcoital day: elaboration of a method.

PubMed

Marovitz, W F; Khan, K M

1977-01-01

A method for removal, fixation, microdissection, and drying of early rat otocyst for examination by the scanning electron microscope is elaborated. Tissues were dissected, fixed as for conventional transmission electron microscopy and dried by critical point evaporation using amylacetate as the transitional fluid and carbon dioxide as the pressure head. Otocysts were either dissected at the time of initial fixation, or subsequent to drying. The otocyst of the 12th postcoital day was used as a model system in this preliminary report. Critical point drying retained the overall configuration and the fine ultrastructural detail of the otocyst. The interior otocystic surface was visualized and cilia bearing cells of the luminal surface were identified. Most if not all of these cells had a comspicuous, but short kinocillum which terminated in an ovoid bulb. The scanning electron microscopic appearance was correlated to the transmission electron microscopic image seen in the second paper in this Supplement.

Environmental scanning electron microscopy in cell biology.

PubMed

McGregor, J E; Staniewicz, L T L; Guthrie Neé Kirk, S E; Donald, A M

2013-01-01

Environmental scanning electron microscopy (ESEM) (1) is an imaging technique which allows hydrated, insulating samples to be imaged under an electron beam. The resolution afforded by this technique is higher than conventional optical microscopy but lower than conventional scanning electron microscopy (CSEM). The major advantage of the technique is the minimal sample preparation needed, making ESEM quick to use and the images less susceptible to the artifacts that the extensive sample preparation usually required for CSEM may introduce. Careful manipulation of both the humidity in the microscope chamber and the beam energy are nevertheless essential to prevent dehydration and beam damage artifacts. In some circumstances it is possible to image live cells in the ESEM (2).In the following sections we introduce the fundamental principles of ESEM imaging before presenting imaging protocols for plant epidermis, mammalian cells, and bacteria. In the first two cases samples are imaged using the secondary electron (topographic) signal, whereas a transmission technique is employed to image bacteria.

Correlative scanning-transmission electron microscopy reveals that a chimeric flavivirus is released as individual particles in secretory vesicles.

PubMed

Burlaud-Gaillard, Julien; Sellin, Caroline; Georgeault, Sonia; Uzbekov, Rustem; Lebos, Claude; Guillaume, Jean-Marc; Roingeard, Philippe

2014-01-01

The intracellular morphogenesis of flaviviruses has been well described, but flavivirus release from the host cell remains poorly documented. We took advantage of the optimized production of an attenuated chimeric yellow fever/dengue virus for vaccine purposes to study this phenomenon by microscopic approaches. Scanning electron microscopy (SEM) showed the release of numerous viral particles at the cell surface through a short-lived process. For transmission electron microscopy (TEM) studies of the intracellular ultrastructure of the small number of cells releasing viral particles at a given time, we developed a new correlative microscopy method: CSEMTEM (for correlative scanning electron microscopy - transmission electron microscopy). CSEMTEM analysis suggested that chimeric flavivirus particles were released as individual particles, in small exocytosis vesicles, via a regulated secretory pathway. Our morphological findings provide new insight into interactions between flaviviruses and cells and demonstrate that CSEMTEM is a useful new method, complementary to SEM observations of biological events by intracellular TEM investigations.

Strain distributions and their influence on electronic structures of WSe2-MoS2 laterally strained heterojunctions

NASA Astrophysics Data System (ADS)

Zhang, Chendong; Li, Ming-Yang; Tersoff, Jerry; Han, Yimo; Su, Yushan; Li, Lain-Jong; Muller, David A.; Shih, Chih-Kang

2018-02-01

Monolayer transition metal dichalcogenide heterojunctions, including vertical and lateral p-n junctions, have attracted considerable attention due to their potential applications in electronics and optoelectronics. Lattice-misfit strain in atomically abrupt lateral heterojunctions, such as WSe2-MoS2, offers a new band-engineering strategy for tailoring their electronic properties. However, this approach requires an understanding of the strain distribution and its effect on band alignment. Here, we study a WSe2-MoS2 lateral heterojunction using scanning tunnelling microscopy and image its moiré pattern to map the full two-dimensional strain tensor with high spatial resolution. Using scanning tunnelling spectroscopy, we measure both the strain and the band alignment of the WSe2-MoS2 lateral heterojunction. We find that the misfit strain induces type II to type I band alignment transformation. Scanning transmission electron microscopy reveals the dislocations at the interface that partially relieve the strain. Finally, we observe a distinctive electronic structure at the interface due to hetero-bonding.

Atmospheric scanning electron microscope for correlative microscopy.

PubMed

Morrison, Ian E G; Dennison, Clare L; Nishiyama, Hidetoshi; Suga, Mitsuo; Sato, Chikara; Yarwood, Andrew; O'Toole, Peter J

2012-01-01

The JEOL ClairScope is the first truly correlative scanning electron and optical microscope. An inverted scanning electron microscope (SEM) column allows electron images of wet samples to be obtained in ambient conditions in a biological culture dish, via a silicon nitride film window in the base. A standard inverted optical microscope positioned above the dish holder can be used to take reflected light and epifluorescence images of the same sample, under atmospheric conditions that permit biochemical modifications. For SEM, the open dish allows successive staining operations to be performed without moving the holder. The standard optical color camera used for fluorescence imaging can be exchanged for a high-sensitivity monochrome camera to detect low-intensity fluorescence signals, and also cathodoluminescence emission from nanophosphor particles. If these particles are applied to the sample at a suitable density, they can greatly assist the task of perfecting the correlation between the optical and electron images. Copyright © 2012 Elsevier Inc. All rights reserved.

A Miniaturized Variable Pressure Scanning Electron Microscope (MVP-SEM) for the Surface of Mars: An Instrument for the Planetary Science Community

NASA Technical Reports Server (NTRS)

Edmunson, J.; Gaskin, J. A.; Danilatos, G.; Doloboff, I. J.; Effinger, M. R.; Harvey, R. P.; Jerman, G. A.; Klein-Schoder, R.; Mackie, W.; Magera, B.;

Correlative Scanning-Transmission Electron Microscopy Reveals that a Chimeric Flavivirus Is Released as Individual Particles in Secretory Vesicles

PubMed Central

Burlaud-Gaillard, Julien; Sellin, Caroline; Georgeault, Sonia; Uzbekov, Rustem; Lebos, Claude; Guillaume, Jean-Marc; Roingeard, Philippe

2014-01-01

The intracellular morphogenesis of flaviviruses has been well described, but flavivirus release from the host cell remains poorly documented. We took advantage of the optimized production of an attenuated chimeric yellow fever/dengue virus for vaccine purposes to study this phenomenon by microscopic approaches. Scanning electron microscopy (SEM) showed the release of numerous viral particles at the cell surface through a short-lived process. For transmission electron microscopy (TEM) studies of the intracellular ultrastructure of the small number of cells releasing viral particles at a given time, we developed a new correlative microscopy method: CSEMTEM (for correlative scanning electron microscopy - transmission electron microscopy). CSEMTEM analysis suggested that chimeric flavivirus particles were released as individual particles, in small exocytosis vesicles, via a regulated secretory pathway. Our morphological findings provide new insight into interactions between flaviviruses and cells and demonstrate that CSEMTEM is a useful new method, complementary to SEM observations of biological events by intracellular TEM investigations. PMID:24681578

Characterization of Discontinuous Coarsening Reaction Products in INCONEL® Alloy 740H® Fusion Welds

NASA Astrophysics Data System (ADS)

Bechetti, Daniel H.; Dupont, John N.; Watanabe, Masashi; de Barbadillo, John J.

2017-04-01

Characterization of γ' coarsened zones (CZs) in alloy 740H fusion welds via a variety of electron microscopy techniques was conducted. The effects of solute partitioning during nonequilibrium solidification on the amount of strengthening precipitates along the grain boundaries were evaluated via electron-probe microanalysis and scanning electron microscopy. Electron backscatter diffraction was used to present evidence for the preferential growth of CZs toward regions of lower γ' content, even if growth in that direction increases grain boundary area. Scanning electron microscopy and image analysis were used to quantify the propensity for CZs to develop along certain segments of the grain boundaries, as governed by the local variations in γ' content. Scanning transmission electron microscopy with X-ray energy-dispersive spectrometry (XEDS) was used to assess the compositions of the matrix and precipitate phases within the CZs and to quantify the segregation of alloying components to the reaction front. Thermodynamic and kinetic modeling were used to compare calculated and experimental compositions. The work presented here provides new insight into the progression of the discontinuous coarsening (DC) reaction in a complex engineering alloy.

Helium ion microscopy and energy selective scanning electron microscopy - two advanced microscopy techniques with complementary applications

NASA Astrophysics Data System (ADS)

Rodenburg, C.; Jepson, M. A. E.; Boden, Stuart A.; Bagnall, Darren M.

2014-06-01

Both scanning electron microscopes (SEM) and helium ion microscopes (HeIM) are based on the same principle of a charged particle beam scanning across the surface and generating secondary electrons (SEs) to form images. However, there is a pronounced difference in the energy spectra of the emitted secondary electrons emitted as result of electron or helium ion impact. We have previously presented evidence that this also translates to differences in the information depth through the analysis of dopant contrast in doped silicon structures in both SEM and HeIM. Here, it is now shown how secondary electron emission spectra (SES) and their relation to depth of origin of SE can be experimentally exploited through the use of energy filtering (EF) in low voltage SEM (LV-SEM) to access bulk information from surfaces covered by damage or contamination layers. From the current understanding of the SES in HeIM it is not expected that EF will be as effective in HeIM but an alternative that can be used for some materials to access bulk information is presented.

Ultrasonic irradiation and its application for improving the corrosion resistance of phosphate coatings on aluminum alloys.

PubMed

Sheng, Minqi; Wang, Chao; Zhong, Qingdong; Wei, Yinyin; Wang, Yi

2010-01-01

In this paper, ultrasonic irradiation was utilized for improving the corrosion resistance of phosphate coatings on aluminum alloys. The chemical composition and morphology of the coatings were analyzed by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The effect of ultrasonic irradiation on the corrosion resistance of phosphate coatings was investigated by polarization curves and electrochemical impedance spectroscopy (EIS). Various effects of the addition of Nd(2)O(3) in phosphating bath on the performance of the coatings were also investigated. Results show that the composition of phosphate coating were Zn(3)(PO(4))(2).4H(2)O(hopeite) and Zn crystals. The phosphate coatings became denser with fewer microscopic holes by utilizing ultrasonic irradiation treatment. The addition of Nd(2)O(3) reduced the crystallinity of the coatings, with the additional result that the crystallites were increasingly nubby and spherical. The corrosion resistance of the coatings was also significantly improved by ultrasonic irradiation treatment; both the anodic and cathodic processes of corrosion taking place on the aluminum alloy substrate were suppressed consequently. In addition, the electrochemical impedance of the coatings was also increased by utilizing ultrasonic irradiation treatment compared with traditional treatment.

Development of Processing Techniques for Advanced Thermal Protection Materials

NASA Technical Reports Server (NTRS)

Selvaduray, Guna; Cox, Michael; Srinivasan, Vijayakumar

1997-01-01

Thermal Protection Materials Branch (TPMB) has been involved in various research programs to improve the properties and structural integrity of the existing aerospace high temperature materials. Specimens from various research programs were brought into the analytical laboratory for the purpose of obtaining and refining the material characterization. The analytical laboratory in TPMB has many different instruments which were utilized to determine the physical and chemical characteristics of materials. Some of the instruments that were utilized by the SJSU students are: Scanning Electron Microscopy (SEM), Energy Dispersive X-ray analysis (EDX), X-ray Diffraction Spectrometer (XRD), Fourier Transform-Infrared Spectroscopy (FTIR), Ultra Violet Spectroscopy/Visible Spectroscopy (UV/VIS), Particle Size Analyzer (PSA), and Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). The above mentioned analytical instruments were utilized in the material characterization process of the specimens from research programs such as: aerogel ceramics (I) and (II), X-33 Blankets, ARC-Jet specimens, QUICFIX specimens and gas permeability of lightweight ceramic ablators. In addition to analytical instruments in the analytical laboratory at TPMB, there are several on-going experiments. One particular experiment allows the measurement of permeability of ceramic ablators. From these measurements, physical characteristics of the ceramic ablators can be derived.

ScAlN etch mask for highly selective silicon etching

DOE PAGES

Henry, Michael David; Young, Travis R.; Griffin, Ben

2017-09-08

Here, this work reports the utilization of a recently developed film, ScAlN, as a silicon etch mask offering significant improvements in high etch selectivity to silicon. Utilization of ScAlN as a fluorine chemistry based deep reactive ion etch mask demonstrated etch selectivity at 23 550:1, four times better than AlN, 11 times better than Al 2O 3, and 148 times better than silicon dioxide with significantly less resputtering at high bias voltage than either Al 2O 3 or AlN. Ellipsometry film thickness measurements show less than 0.3 nm/min mask erosion rates for ScAlN. Micromasking of resputtered Al for Al 2Omore » 3, AlN, and ScAlN etch masks is also reported here, utilizing cross-sectional scanning electron microscope and confocal microscope roughness measurements. With lower etch bias, the reduced etch rate can be optimized to achieve a trench bottom surface roughness that is comparable to SiO 2 etch masks. Etch mask selectivity enabled by ScAlN is likely to make significant improvements in microelectromechanical systems, wafer level packaging, and plasma dicing of silicon.« less

Graphene-supporting films and low-voltage STEM in SEM toward imaging nanobio materials without staining: Observation of insulin amyloid fibrils.

PubMed

Ogawa, Takashi; Gang, Geun Won; Thieu, Minh Thu; Kwon, Hyuksang; Ahn, Sang Jung; Ha, Tai Hwan; Cho, Boklae

2017-05-01

Utilization of graphene-supporting films and low-voltage scanning transmission electron microscopy (LV-STEM) in scanning electron microscopy (SEM) is shown to be an effective means of observing unstained nanobio materials. Insulin amyloid fibrils, which are implicated as a cause of type II diabetes, are formed in vitro and observed without staining at room temperature. An in-lens cold field-emission SEM, equipped with an additional homemade STEM detector, provides dark field (DF)-STEM images in the low energy range of 5-30keV, together with secondary electron (SE) images. Analysis based on Lenz's theory is used to interpret the experimental results. Graphene films, where the fibrils are deposited, reduce the background level of the STEM images compared with instances when conventional amorphous carbon films are used. Using 30keV, which is lower than that for conventional TEM (100-300keV), together with low detection angles (15-55mrad) enhances the signals from the fibrils. These factors improve image quality, which enables observation of thin fibrils with widths of 7-8nm. STEM imaging clearly reveals a twisted-ribbon structure of a fibril, and SE imaging shows an emphasized striped pattern of the fibril. The LV-STEM in SEM enables acquisition of two types of images of an identical fibril in a single instrument, which is useful for understanding the structure. This study expands the application of SEM to other systems of interest, which is beneficial to a large number of users. The method in this study can be applied to the observation of various nanobio materials and analysis of their native structures, thus contributing to research in materials and life sciences. Copyright © 2017 Elsevier Ltd. All rights reserved.

Structural, optical and dielectric investigation of CdFe2O4 nanoparticles

NASA Astrophysics Data System (ADS)

Sagadevan, Suresh; Pal, Kaushik; Zaman Chowdhury, Zaira; Enamul Hoque, Md

2017-07-01

A simple thermal decomposition technique has been executed for the synthesis of cadmium ferrite (CdFe2O4) nanoparticles. With the help of x-ray diffraction; scanning electron microscopy, energy-dispersive x-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy the prepared nanoparticles were identified. The crystal size of the average particles aggregated and was found approximately to be 10-14 nm by means of XRD studies. However, the results of high-resolution transmission electron microscopy (HR-TEM) investigation ensured distinguished nanoparticles, and also the polycrystalline nature of those nanoparticles was confirmed by selected area diffraction (SAED) patterns. The scanning electron microscopy (SEM) images explored a random distribution of grains within the sample. Thin film surface topology of roughness and surface current measurement were studied by atomic force microscopy (TP-AFM, C-AFM). Hence, from the ultraviolet-visible (UV) spectroscopic absorption illustrated significant optical properties. Moreover, the optical energy band gap (E g) of CdFe2O4 nanoparticle was determined to be 1.74 eV. By studying the variation of dielectric constant and dielectric loss with respect to frequency, the CdFe2O4 nanoparticles electrical properties were analyzed. Analysis in the real and imaginary part of impedance explained their frequency and temperature dependence of the CdFe2O4 nanoparticles. The traditional solution-phase organometallic approach provides an effective way to synthesize high quality hydrophobic semiconductor-CdFe2O4 nanoparticles. Our simple, cost-effective approach is quite general, which is applicable to other nanomaterials, and it utilizes the currently mature in Nano-chemistry. The nanocomposite assemblies’ exhibit strong anisotropic optical and electrical properties are open up new possibilities in remarkable applications for optoelectronics in the near future.

The birth and evolution of surface science: Child of the union of science and technology

PubMed Central

Duke, C. B.

2003-01-01

This article is an account of the birth and evolution of surface science as an interdisciplinary research area. Surface science emanated from the confluence of concepts and tools in physics and chemistry with technological innovations that made it possible to determine the structure and properties of surfaces and interfaces and the dynamics of chemical reactions at surfaces. The combination in the 1960s and 1970s of ultra-high-vacuum (i.e., P < 10−7 Pascal or 10−9 Torr) technology with the recognition that electrons in the energy range from 50 to 500 eV exhibited inelastic collision mean free paths of the order of a few angstroms fostered an explosion of activity. The results were a reformulation of the theory of electron solid scattering, the nearly universal use of electron spectroscopies for surface characterization, the rise of surface science as an independent interdisciplinary research area, and the emergence of the American Vacuum Society (AVS) as a major international scientific society. The rise of microelectronics in the 1970s and 1980s resulted in huge increases in computational power. These increases enabled more complex experiments and the utilization of density functional theory for the quantitative prediction of surface structure and dynamics. Development of scanning-probe microscopies in the 1990s led to atomic-resolution images of macroscopic surfaces and interfaces as well as videos of atoms moving about on surfaces during growth and diffusion. Scanning probes have since brought solid–liquid interfaces into the realm of atomic-level surface science, expanding its scope to more complex systems, including fragile biological materials and processes. PMID:12651946

Serial sectioning methods for 3D investigations in materials science.

PubMed

Zankel, Armin; Wagner, Julian; Poelt, Peter

2014-07-01

A variety of methods for the investigation and 3D representation of the inner structure of materials has been developed. In this paper, techniques based on slice and view using scanning microscopy for imaging are presented and compared. Three different methods of serial sectioning combined with either scanning electron or scanning ion microscopy or atomic force microscopy (AFM) were placed under scrutiny: serial block-face scanning electron microscopy, which facilitates an ultramicrotome built into the chamber of a variable pressure scanning electron microscope; three-dimensional (3D) AFM, which combines an (cryo-) ultramicrotome with an atomic force microscope, and 3D FIB, which delivers results by slicing with a focused ion beam. These three methods complement one another in many respects, e.g., in the type of materials that can be investigated, the resolution that can be obtained and the information that can be extracted from 3D reconstructions. A detailed review is given about preparation, the slice and view process itself, and the limitations of the methods and possible artifacts. Applications for each technique are also provided. Copyright © 2014 Elsevier Ltd. All rights reserved.

Real-Time Electronic Dashboard Technology and Its Use to Improve Pediatric Radiology Workflow.

PubMed

Shailam, Randheer; Botwin, Ariel; Stout, Markus; Gee, Michael S

The purpose of our study was to create a real-time electronic dashboard in the pediatric radiology reading room providing a visual display of updated information regarding scheduled and in-progress radiology examinations that could help radiologists to improve clinical workflow and efficiency. To accomplish this, a script was set up to automatically send real-time HL7 messages from the radiology information system (Epic Systems, Verona, WI) to an Iguana Interface engine, with relevant data regarding examinations stored in an SQL Server database for visual display on the dashboard. Implementation of an electronic dashboard in the reading room of a pediatric radiology academic practice has led to several improvements in clinical workflow, including decreasing the time interval for radiologist protocol entry for computed tomography or magnetic resonance imaging examinations as well as fewer telephone calls related to unprotocoled examinations. Other advantages include enhanced ability of radiologists to anticipate and attend to examinations requiring radiologist monitoring or scanning, as well as to work with technologists and operations managers to optimize scheduling in radiology resources. We foresee increased utilization of electronic dashboard technology in the future as a method to improve radiology workflow and quality of patient care. Copyright © 2017 Elsevier Inc. All rights reserved.

Characterization of Thin Film Materials using SCAN meta-GGA, an Accurate Nonempirical Density Functional

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buda, I. G.; Lane, C.; Barbiellini, B.

We discuss self-consistently obtained ground-state electronic properties of monolayers of graphene and a number of ’beyond graphene’ compounds, including films of transition-metal dichalcogenides (TMDs), using the recently proposed strongly constrained and appropriately normed (SCAN) meta-generalized gradient approximation (meta-GGA) to the density functional theory. The SCAN meta-GGA results are compared with those based on the local density approximation (LDA) as well as the generalized gradient approximation (GGA). As expected, the GGA yields expanded lattices and softened bonds in relation to the LDA, but the SCAN meta-GGA systematically improves the agreement with experiment. Our study suggests the efficacy of the SCAN functionalmore » for accurate modeling of electronic structures of layered materials in high-throughput calculations more generally.« less

Characterization of Thin Film Materials using SCAN meta-GGA, an Accurate Nonempirical Density Functional

DOE PAGES

Buda, I. G.; Lane, C.; Barbiellini, B.; ...

2017-03-23

We discuss self-consistently obtained ground-state electronic properties of monolayers of graphene and a number of ’beyond graphene’ compounds, including films of transition-metal dichalcogenides (TMDs), using the recently proposed strongly constrained and appropriately normed (SCAN) meta-generalized gradient approximation (meta-GGA) to the density functional theory. The SCAN meta-GGA results are compared with those based on the local density approximation (LDA) as well as the generalized gradient approximation (GGA). As expected, the GGA yields expanded lattices and softened bonds in relation to the LDA, but the SCAN meta-GGA systematically improves the agreement with experiment. Our study suggests the efficacy of the SCAN functionalmore » for accurate modeling of electronic structures of layered materials in high-throughput calculations more generally.« less

Electronic Inventory Systems and Barcode Technology: Impact on Pharmacy Technical Accuracy and Error Liability

PubMed Central

Oldland, Alan R.; May, Sondra K.; Barber, Gerard R.; Stolpman, Nancy M.

2015-01-01

Purpose: To measure the effects associated with sequential implementation of electronic medication storage and inventory systems and product verification devices on pharmacy technical accuracy and rates of potential medication dispensing errors in an academic medical center. Methods: During four 28-day periods of observation, pharmacists recorded all technical errors identified at the final visual check of pharmaceuticals prior to dispensing. Technical filling errors involving deviations from order-specific selection of product, dosage form, strength, or quantity were documented when dispensing medications using (a) a conventional unit dose (UD) drug distribution system, (b) an electronic storage and inventory system utilizing automated dispensing cabinets (ADCs) within the pharmacy, (c) ADCs combined with barcode (BC) verification, and (d) ADCs and BC verification utilized with changes in product labeling and individualized personnel training in systems application. Results: Using a conventional UD system, the overall incidence of technical error was 0.157% (24/15,271). Following implementation of ADCs, the comparative overall incidence of technical error was 0.135% (10/7,379; P = .841). Following implementation of BC scanning, the comparative overall incidence of technical error was 0.137% (27/19,708; P = .729). Subsequent changes in product labeling and intensified staff training in the use of BC systems was associated with a decrease in the rate of technical error to 0.050% (13/26,200; P = .002). Conclusions: Pharmacy ADCs and BC systems provide complementary effects that improve technical accuracy and reduce the incidence of potential medication dispensing errors if this technology is used with comprehensive personnel training. PMID:25684799

Electronic inventory systems and barcode technology: impact on pharmacy technical accuracy and error liability.

PubMed

Oldland, Alan R; Golightly, Larry K; May, Sondra K; Barber, Gerard R; Stolpman, Nancy M

2015-01-01

To measure the effects associated with sequential implementation of electronic medication storage and inventory systems and product verification devices on pharmacy technical accuracy and rates of potential medication dispensing errors in an academic medical center. During four 28-day periods of observation, pharmacists recorded all technical errors identified at the final visual check of pharmaceuticals prior to dispensing. Technical filling errors involving deviations from order-specific selection of product, dosage form, strength, or quantity were documented when dispensing medications using (a) a conventional unit dose (UD) drug distribution system, (b) an electronic storage and inventory system utilizing automated dispensing cabinets (ADCs) within the pharmacy, (c) ADCs combined with barcode (BC) verification, and (d) ADCs and BC verification utilized with changes in product labeling and individualized personnel training in systems application. Using a conventional UD system, the overall incidence of technical error was 0.157% (24/15,271). Following implementation of ADCs, the comparative overall incidence of technical error was 0.135% (10/7,379; P = .841). Following implementation of BC scanning, the comparative overall incidence of technical error was 0.137% (27/19,708; P = .729). Subsequent changes in product labeling and intensified staff training in the use of BC systems was associated with a decrease in the rate of technical error to 0.050% (13/26,200; P = .002). Pharmacy ADCs and BC systems provide complementary effects that improve technical accuracy and reduce the incidence of potential medication dispensing errors if this technology is used with comprehensive personnel training.

Quasi-parallel precession diffraction: Alignment method for scanning transmission electron microscopes.

PubMed

Plana-Ruiz, S; Portillo, J; Estradé, S; Peiró, F; Kolb, Ute; Nicolopoulos, S

2018-06-06

A general method to set illuminating conditions for selectable beam convergence and probe size is presented in this work for Transmission Electron Microscopes (TEM) fitted with µs/pixel fast beam scanning control, (S)TEM, and an annular dark field detector. The case of interest of beam convergence and probe size, which enables diffraction pattern indexation, is then used as a starting point in this work to add 100 Hz precession to the beam while imaging the specimen at a fast rate and keeping the projector system in diffraction mode. The described systematic alignment method for the adjustment of beam precession on the specimen plane while scanning at fast rates is mainly based on the sharpness of the precessed STEM image. The complete alignment method for parallel condition and precession, Quasi-Parallel PED-STEM, is presented in block diagram scheme, as it has been tested on a variety of instruments. The immediate application of this methodology is that it renders the TEM column ready for the acquisition of Precessed Electron Diffraction Tomographies (EDT) as well as for the acquisition of slow Precessed Scanning Nanometer Electron Diffraction (SNED). Examples of the quality of the Precessed Electron Diffraction (PED) patterns and PED-STEM alignment images are presented with corresponding probe sizes and convergence angles. Copyright © 2018. Published by Elsevier B.V.

Effects of sintering atmosphere on the physical and mechanical properties of modified BOF slag glass

NASA Astrophysics Data System (ADS)

Dai, Wen-bin; Li, Yu; Cang, Da-qiang; Zhou, Yuan-yuan; Fan, Yong

2014-05-01

This study proposes an efficient way to utilize all the chemical components of the basic oxygen furnace (BOF) slag to prepare high value-added glass-ceramics. A molten modified BOF slag was converted from the melting BOF slag by reducing it and separating out iron component in it, and the modified BOF slag was then quenched in water to form glasses with different basicities. The glasses were subsequently sintered in the temperature range of 600-1000°C in air or nitrogen atmosphere for 1 h. The effects of different atmospheres on the physical and mechanical properties of sintered samples were studied by using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) and by conducting experiment on evaluating the sintering shrinkage, water absorption and bulk density. It is found that the kinetics of the sintering process is significantly affected by sintering atmosphere. In particular, compared with sintering in air atmosphere, sintering in N2 atmosphere promotes the synergistic growth of pyroxene and melilite crystalline phases, which can contribute to better mechanical properties and denser microstructure.

Chemically prepared La2Se3 nanocubes thin film for supercapacitor application.

PubMed

Patil, S J; Lokhande, V C; Chodankar, N R; Lokhande, C D

2016-05-01

Lanthanum selenide (La2Se3) nanocubes thin film is prepared via successive ionic layer adsorption and reaction (SILAR) method and utilized for energy storage application. The prepared La2Se3 thin film is characterized by X-ray diffraction, field emission scanning electron microscopy and contact angle measurement techniques for structural, surface morphological and wettability studies, respectively. Energy dispersive X-ray microanalysis (EDAX) is performed in order to obtain the elemental composition of the thin film. The La2Se3 film electrode shows a maximum specific capacitance of 363 F g(-1) in a 0.8 M LiClO4/PC electrolyte at a scan rate of 5 mV s(-1) within 1.3 V/SCE potential range. The specific capacitive retention of 83 % of La2Se3 film electrode is obtained over 1000 cyclic voltammetry cycles. The predominant performance, such as high energy (80 Wh kg(-1)) and power density (2.5 kW kg(-1)), indicates that La2Se3 film electrode facilitates fast ion diffusion during redox processes. Copyright © 2016 Elsevier Inc. All rights reserved.

The New Microwave Temperature and Humidity Profiler (MTHP) Airborne Instrument

NASA Astrophysics Data System (ADS)

Lim, B.; Bendig, R.; Denning, R.; Pandian, P.; Read, W. G.; Tanner, A.

2016-12-01

The Jet Propulsion Laboratory (JPL) has developed a next generation sensor, the Microwave Temperature and Humidity Profiler (MTHP) for use on airborne platforms. The instrument measures the 60 GHz oxygen band and 183 GHz water vapor band, and scans ahead of the aircraft flight path, allowing for atmospheric retrievals above and below the aircraft, to generate vertical profiles. The millimeter wave microwave receivers utilize low noise amplifiers made on the 35 nm indium phosphide (InP) High Electron Mobility Transistors (HEMTs) process that offer low noise figures ( 4 dB). Continuous calibration is performed with a novel rotating drum, through an aperture matched to the measurement frequencies, with two external targets - one at ambient and another heated to 55oC. The instrument performs a scan of the vertical structure of the atmosphere and calibration targets every 1.5 seconds The instrument has recently flown on the Gulfstream 2 in June 2016 and participated in the NCAR ARISTO C-130 flight test campaign in August 2016. The performance of the instrument during these campaigns, will be presented.

Efficient phase contrast imaging in STEM using a pixelated detector. Part 1: Experimental demonstration at atomic resolution

DOE PAGES

Pennycook, Timothy J.; Lupini, Andrew R.; Yang, Hao; ...

2014-10-15

In this paper, we demonstrate a method to achieve high efficiency phase contrast imaging in aberration corrected scanning transmission electron microscopy (STEM) with a pixelated detector. The pixelated detector is used to record the Ronchigram as a function of probe position which is then analyzed with ptychography. Ptychography has previously been used to provide super-resolution beyond the diffraction limit of the optics, alongside numerically correcting for spherical aberration. Here we rely on a hardware aberration corrector to eliminate aberrations, but use the pixelated detector data set to utilize the largest possible volume of Fourier space to create high efficiency phasemore » contrast images. The use of ptychography to diagnose the effects of chromatic aberration is also demonstrated. In conclusion, the four dimensional dataset is used to compare different bright field detector configurations from the same scan for a sample of bilayer graphene. Our method of high efficiency ptychography produces the clearest images, while annular bright field produces almost no contrast for an in-focus aberration-corrected probe.« less

Multimodal hard x-ray imaging with resolution approaching 10 nm for studies in material science

NASA Astrophysics Data System (ADS)

Yan, Hanfei; Bouet, Nathalie; Zhou, Juan; Huang, Xiaojing; Nazaretski, Evgeny; Xu, Weihe; Cocco, Alex P.; Chiu, Wilson K. S.; Brinkman, Kyle S.; Chu, Yong S.

2018-03-01

We report multimodal scanning hard x-ray imaging with spatial resolution approaching 10 nm and its application to contemporary studies in the field of material science. The high spatial resolution is achieved by focusing hard x-rays with two crossed multilayer Laue lenses and raster-scanning a sample with respect to the nanofocusing optics. Various techniques are used to characterize and verify the achieved focus size and imaging resolution. The multimodal imaging is realized by utilizing simultaneously absorption-, phase-, and fluorescence-contrast mechanisms. The combination of high spatial resolution and multimodal imaging enables a comprehensive study of a sample on a very fine length scale. In this work, the unique multimodal imaging capability was used to investigate a mixed ionic-electronic conducting ceramic-based membrane material employed in solid oxide fuel cells and membrane separations (compound of Ce0.8Gd0.2O2‑x and CoFe2O4) which revealed the existence of an emergent material phase and quantified the chemical complexity at the nanoscale.

Concept Design of a Multi-Band Shared Aperture Reflectarray/Reflector Antenna

NASA Technical Reports Server (NTRS)

Spence, Thomas; Cooley, Michael E.; Stenger, Peter; Park, Richard; Li, Lihua; Racette, Paul; Heymsfield, Gerald; Mclinden, Matthew

2016-01-01

A scalable dual-band (Ka/W) shared-aperture antenna system design has been developed as a proposed solution to meet the needs of the planned NASA Earth Science Aerosol, Clouds, and Ecosystem (ACE) mission. The design is comprised of a compact Cassegrain reflector/reflectarray with a fixed pointing W-band feed and a cross track scanned Ka-band Active Electronically Scanned Array (AESA). Critical Sub-scale prototype testing and flight tests have validated some of the key aspects of this innovative antenna design, including the low loss reflector/reflectarray surface. More recently the science community has expressed interest in a mission that offers the ability to measure precipitation in addition to clouds and aerosols. In this paper we present summaries of multiple designs that explore options for realizing a tri-frequency (Ku/Ka/W), shared-aperture antenna system to meet these science objectives. Design considerations include meeting performance requirements while emphasizing payload size, weight, prime power, and cost. The extensive trades and lessons learned from our previous dual-band ACE system development were utilized as the foundation for this work.

Thermal Characterization of Lauric-Stearic Acid/Expanded Graphite Eutectic Mixture as Phase Change Materials.

PubMed

Zhu, Hua; Zhang, Peng; Meng, Zhaonan; Li, Ming

2015-04-01

The eutectic mixture of lauric acid (LA) and stearic acid (SA) is a desirable phase change material (PCM) due to the constant melting temperature and large latent heat. However, its poor thermal conductivity has hampered its broad utilization. In the present study, pure LA, SA and the mixtures with various mass fractions of LA-SA were used as the basic PCMs, and 10 wt% expanded graphite (EG) was added to enhance the thermal conductivities. The phase change behaviors, microstructural analysis, thermal conductivities and thermal stabilities of the mixtures of PCMs were investigated by differential scanning calorimetry (DSC), scanning electronic microscope (SEM), transient plane source (TPS) and thermogravimetric analysis (TGA), respectively. The results show that the LA-SA binary mixture of mixture ratio of 76.3 wt%: 23.7 wt% forms an eutectic mixture, which melts at 38.99 °C and has a latent heat of 159.94 J/g. The melted fatty acids are well absorbed by the porous network of EG and they have a good thermal stability. Furthermore, poor thermal conductivities can be well enhanced by the addition of EG.

Linkages Between Clinical Practices and Community Organizations for Prevention: A Literature Review and Environmental Scan

PubMed Central

Hinnant, Laurie W.; Kane, Heather; Horne, Joseph; McAleer, Kelly; Roussel, Amy

2012-01-01

Objectives. We conducted a literature review and environmental scan to develop a framework for interventions that utilize linkages between clinical practices and community organizations for the delivery of preventive services, and to identify and characterize these efforts. Methods. We searched 4 major health services and social science electronic databases and conducted an Internet search to identify examples of linkage interventions in the areas of tobacco cessation, obesity, nutrition, and physical activity. Results. We identified 49 interventions, of which 18 examples described their evaluation methods or reported any intervention outcomes. Few conducted evaluations that were rigorous enough to capture changes in intermediate or long-term health outcomes. Outcomes in these evaluations were primarily patient-focused and did not include organizational or linkage characteristics. Conclusions. An attractive option to increase the delivery of preventive services is to link primary care practices to community organizations; evidence is not yet conclusive, however, that such linkage interventions are effective. Findings provide recommendations to researchers and organizations that fund research, and call for a framework and metrics to study linkage interventions. PMID:22690974

Lipase-inorganic hybrid nanoflower constructed through biomimetic mineralization: A new support for biodiesel synthesis.

PubMed

Jiang, Wei; Wang, Xinghuo; Yang, Jiebing; Han, Haobo; Li, Quanshun; Tang, Jun

2018-03-15

We reported a facile, economic and green method based on biomimetic mineralization to acquire lipase-inorganic hybrid nanoflower, which was then employed as a biocatalyst for biodiesel production. In the hybrid nanoflower, enzyme molecules and Cu 2+ ions were utilized as the organic and inorganic components, respectively. The morphology of nanoflower and the distribution and loading of proteins were systematically characterized by scanning electron microscopy, confocal laser scanning microscopy and ultraviolet-visible spectroscopy, which indicated the successful encapsulation of lipase in the hybrid nanoflower. Using the hydrolysis of p-nitrophenyl caprylate as a model, lipase-inorganic hybrid nanoflower was observed to possess favorable catalytic activity and stability in the ester hydrolysis. Further, the hybrid nanoflower was used as a catalyst for biodiesel production, in which it could convert sunflower oil to biodiesel with 96.5% conversion and remain 72.5% conversion after being used for 5 cycles. Thus, the lipase-inorganic hybrid nanoflower is potential to be used as an economically viable biocatalyst for the production of biofuel as the future petrol-fuel replacement. Copyright © 2017 Elsevier Inc. All rights reserved.

Cellular compatibility of highly degradable bioactive ceramics for coating of metal implants.

PubMed

Radetzki, F; Wohlrab, D; Zeh, A; Delank, K S; Mendel, T; Berger, G; Syrowatka, F; Mayr, O; Bernstein, A

2011-01-01

Resorbable ceramics can promote the bony integration of implants. Their rate of degradation should ideally be synchronized with bone regeneration. This study examined the effect of rapidly resorbable calcium phosphate ceramics 602020, GB14, 305020 on adherence, proliferation and morphology of human bone-derived cells (HBDC) in comparison to β-TCP. The in vitro cytotoxicity was determined by the microculture tetrazolium (MTT) assay. HBDC were grown on the materials for 3, 7, 11, 15 and 19 days and counted. Cell morphology, cell attachment, cell spreading and the cytoskeletal organization of HBDC cultivated on the substrates were investigated using laser scanning microscopy and environmental scanning electron microscopy. All substrates supported sufficient cellular growth for 19 days and showed no cytotoxicity. On each material an identical cell colonisation of well communicating, polygonal, vital cells with strong focal contacts was verified. HBDC showed numerous well defined stress fibres which give proof of well spread and strongly anchored cells. Porous surfaces encouraged the attachment and spreading of HBDC. Further investigations regarding long term biomaterial/cell interactions in vitro and in vivo are required to confirm the utility of the new biomaterials.

Concept Design of a Multi-Band Shared Aperture Reflectarray/Reflector Antenna

NASA Technical Reports Server (NTRS)

Spence, Thomas; Cooley, Michael; Stenger, Peter; Park, Richard; Li, Lihua; Racette, Paul; Heymsfield, Gerald; Mclinden, Matthew

2016-01-01

A scalable dual-band (KaW) shared-aperture antenna system design has been developed as a proposed solution to meet the needs of the planned NASA Earth Science Aerosol, Clouds, and Ecosystem (ACE) mission. The design is comprised of a compact Cassegrain reflector/reflectarray with a fixed pointing W-band feed and a cross track scanned Ka-band Active Electronically Scanned Array (AESA). Critical Sub-scale prototype testing and flight tests have validated some of the key aspects of this innovative antenna design, including the low loss reflector/reflectarray surface.More recently the science community has expressed interest in a mission that offers the ability to measure precipitation in addition to clouds and aerosols. In this paper we present summaries of multiple designs that explore options for realizing a tri-frequency (KuKaW), shared-aperture antenna system to meet these science objectives. Design considerations include meeting performance requirements while emphasizing payload size, weight, prime power, and cost. The extensive trades and lessons learned from our previous dual-band ACE system development were utilized as the foundation for this work.

Characterization of non-conductive materials using field emission scanning electron microscopy

NASA Astrophysics Data System (ADS)

Cao, Cong; Gao, Ran; Shang, Huayan; Peng, Tingting

2016-01-01

With the development of science and technology, field emission scanning electron microscope (FESEM) plays an important role in nano-material measurements because of its advantages of high magnification, high resolution and easy operation. A high-quality secondary electron image is a significant prerequisite for accurate and precise length measurements. In order to obtain high-quality secondary electron images, the conventional treatment method for non-conductive materials is coating conductive films with gold, carbon or platinum to reduce charging effects, but this method will cover real micro structures of materials, change the sample composition properties and meanwhile introduce a relatively big error to nano-scale microstructure measurements. This paper discusses how to reduce or eliminate the impact of charging effects on image quality to the greatest extent by changing working conditions, such as voltage, stage bias, scanning mode and so on without treatment of coating, to obtain real and high-quality microstructure information of materials.

cnvScan: a CNV screening and annotation tool to improve the clinical utility of computational CNV prediction from exome sequencing data.

PubMed

Samarakoon, Pubudu Saneth; Sorte, Hanne Sørmo; Stray-Pedersen, Asbjørg; Rødningen, Olaug Kristin; Rognes, Torbjørn; Lyle, Robert

2016-01-14

With advances in next generation sequencing technology and analysis methods, single nucleotide variants (SNVs) and indels can be detected with high sensitivity and specificity in exome sequencing data. Recent studies have demonstrated the ability to detect disease-causing copy number variants (CNVs) in exome sequencing data. However, exonic CNV prediction programs have shown high false positive CNV counts, which is the major limiting factor for the applicability of these programs in clinical studies. We have developed a tool (cnvScan) to improve the clinical utility of computational CNV prediction in exome data. cnvScan can accept input from any CNV prediction program. cnvScan consists of two steps: CNV screening and CNV annotation. CNV screening evaluates CNV prediction using quality scores and refines this using an in-house CNV database, which greatly reduces the false positive rate. The annotation step provides functionally and clinically relevant information using multiple source datasets. We assessed the performance of cnvScan on CNV predictions from five different prediction programs using 64 exomes from Primary Immunodeficiency (PIDD) patients, and identified PIDD-causing CNVs in three individuals from two different families. In summary, cnvScan reduces the time and effort required to detect disease-causing CNVs by reducing the false positive count and providing annotation. This improves the clinical utility of CNV detection in exome data.

The utility of repeat sestamibi scans in patients with primary hyperparathyroidism after an initial negative scan.

PubMed

Krishnamurthy, Vikram D; Sound, Sara; Okoh, Alexis K; Yazici, Pinar; Yigitbas, Hakan; Neumann, Donald; Doshi, Krupa; Berber, Eren

2017-06-01

We analyzed the utility of repeated sestambi scans in patients with primary hyperparathyroidism and its effects on operative referral. We carried out a retrospective review of patients with primary hyperparathyroidism who underwent repeated sestambi scans exclusively within our health system between 1996-2015. Patient demographic, presentation, laboratory, imaging, operative, and pathologic data were reviewed. Univariate analysis with JMP Pro v12 was used to identify factors associated with conversion from an initial negative to a subsequent positive scan. After exclusion criteria (including reoperations), we identified 49 patients in whom 59% (n = 29) of subsequent scans remained negative and 41% (n = 20) converted to positive. Factors associated with an initial negative to a subsequent positive scan included classic presentation and second scans with iodine subtraction (P = .04). Nonsurgeons were less likely to order an iodine-subtraction scan (P < .05). Fewer patients with negative imaging were referred to surgery (33% vs 100%, P = .005), and median time to operation after the first negative scan was 25 months (range 1.4-119). Surgeon-performed ultrasonography had greater sensitivity and positive predictive value than repeated sestamibi scans. Negative sestambi scans decreased and delayed operative referral. Consequently, we identified several process improvement initiatives, including education regarding superior institutional imaging. Combining all findings, we created an algorithm for evaluating patients with primary hyperparathyroidism after initially negative sestamibi scans, which incorporates surgeon-performed ultrasonography. Copyright © 2016 Elsevier Inc. All rights reserved.

High-resolution low-dose scanning transmission electron microscopy.

PubMed

Buban, James P; Ramasse, Quentin; Gipson, Bryant; Browning, Nigel D; Stahlberg, Henning

2010-01-01

During the past two decades instrumentation in scanning transmission electron microscopy (STEM) has pushed toward higher intensity electron probes to increase the signal-to-noise ratio of recorded images. While this is suitable for robust specimens, biological specimens require a much reduced electron dose for high-resolution imaging. We describe here protocols for low-dose STEM image recording with a conventional field-emission gun STEM, while maintaining the high-resolution capability of the instrument. Our findings show that a combination of reduced pixel dwell time and reduced gun current can achieve radiation doses comparable to low-dose TEM.

Characterizing individual particles on tree leaves using computer automated scanning electron microscopy

Treesearch

D. L. Johnson; D. J. Nowak; V. A. Jouraeva

1999-01-01

Leaves from twenty-three deciduous tree species and five conifer species were collected within a limited geographic range (1 km radius) and evaluated for possible application of scanning electron microscopy and X-ray microanalysis techniques of individual particle analysis (IPA). The goal was to identify tree species with leaves suitable for the automated...

Observing Tin-Lead Alloys by Scanning Electron Microscopy: A Physical Chemistry Experiment Investigating Macro-Level Behaviors and Micro-Level Structures

ERIC Educational Resources Information Center

Wang, Yue; Xu, Xinhua; Wu, Meifen; Hu, Huikang; Wang, Xiaogang

2015-01-01

Scanning electron microscopy (SEM) was introduced into undergraduate physical chemistry laboratory curriculum to help students observe the phase composition and morphology characteristics of tin-lead alloys and thus further their understanding of binary alloy phase diagrams. The students were captivated by this visual analysis method, which…

A fast image simulation algorithm for scanning transmission electron microscopy.

PubMed

Ophus, Colin

2017-01-01

Image simulation for scanning transmission electron microscopy at atomic resolution for samples with realistic dimensions can require very large computation times using existing simulation algorithms. We present a new algorithm named PRISM that combines features of the two most commonly used algorithms, namely the Bloch wave and multislice methods. PRISM uses a Fourier interpolation factor f that has typical values of 4-20 for atomic resolution simulations. We show that in many cases PRISM can provide a speedup that scales with f 4 compared to multislice simulations, with a negligible loss of accuracy. We demonstrate the usefulness of this method with large-scale scanning transmission electron microscopy image simulations of a crystalline nanoparticle on an amorphous carbon substrate.

A fast image simulation algorithm for scanning transmission electron microscopy

DOE PAGES

Ophus, Colin

2017-05-10

Image simulation for scanning transmission electron microscopy at atomic resolution for samples with realistic dimensions can require very large computation times using existing simulation algorithms. Here, we present a new algorithm named PRISM that combines features of the two most commonly used algorithms, namely the Bloch wave and multislice methods. PRISM uses a Fourier interpolation factor f that has typical values of 4-20 for atomic resolution simulations. We show that in many cases PRISM can provide a speedup that scales with f 4 compared to multislice simulations, with a negligible loss of accuracy. We demonstrate the usefulness of this methodmore » with large-scale scanning transmission electron microscopy image simulations of a crystalline nanoparticle on an amorphous carbon substrate.« less

Effect of reinforcing particle type on morphology and age-hardening behavior of Al–4.5 wt.% Cu based nanocomposites synthesized through mechanical milling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mostaed, A., E-mail: alimostaed@yahoo.com; Saghafian, H.; Mostaed, E.

2013-02-15

The effects of reinforcing particle type (SiC and TiC) on morphology and precipitation hardening behavior of Al–4.5%Cu based nanocomposites synthesized via mechanical milling were investigated in the current work. In order to study the microstructure and morphology of mechanically milled powder, X-ray diffraction technique, scanning electron microscopy and high resolution transmission electron microscopy were utilized. Results revealed that at the early stages of mechanical milling, when reinforcing particles are polycrystal, the alloying process is enhanced more in the case of using the TiC particles as reinforcement. But, at the final stages of mechanical milling, when reinforcing particles are single crystal,more » the alloying process is enhanced more in the case of using the SiC ones. Transmission electron microscopy results demonstrated that Al–4.5 wt.%Cu based nanocomposite powders were synthesized and confirmed that the mutual diffusion of aluminum and copper occurs through the interfacial plane of (200). The hardness results showed that not only does introducing 4 vol.% of reinforcing particles (SiC or TiC) considerably decrease the porosity of the bulk composite samples, but also it approximately doubles the hardness of Al–4.5 wt.%Cu alloy (53.4 HB). Finally, apart from TEM and scanning electron microscopy observation which are localized, a decline in hardness in the TiC and SiC contained samples, respectively, after 1.5 and 2 h aging time at 473 K proves the fact that the size of SiC particles is smaller than the size of the TiC ones. - Highlights: ► HRTEM results show mutual diffusion of Al and Cu occurs through the (200) planes. ► TiC particles enhance alloying process more than the SiC ones at the early stages of MM. ► SiC particles enhance alloying process more than the TiC ones at the final stages of MM.« less

Evaluating the effectiveness of integrating food science lessons in high school Biology curriculum in comparison to high school Chemistry curriculum

NASA Astrophysics Data System (ADS)

Ilogebe, Amamchukwu Bernard

Binder-jet 3D printing has been one of the additive manufacturing techniques employed in fabrication of intricate parts, by utilizing metal powders. Liquid metal infiltration of bronze into binder-jet printed structural amorphous metal resulted in a net shape, fully-dense parts were made. The final part was characterized by means of scanning electron microscopy, electron dispersive x-ray spectroscopy and computed tomography. The densification in the binder-jet samples was also compared to die-pressed ones, and was found to be 3.96g/cm 3 and 3.89g/cm3. Thus, binder-jet can be used to model a die-pressed part. Scanning electron micrograph displayed the presence of considerable porosity in the sintered binder-jet samples, as well as some limited porosity in the infiltrated samples. Evident also from SEM analysis was the presence of internal powder micro pores. Electron dispersive spectroscopy results show that the bronze filled out the pores as was expected. According to the computed tomography results, the un-infiltrated sample has an average porosity of 34%, while the bronze-infiltrated samples have an average porosity of 1%. Micro-indentation was also performed on the infiltrated and uninfiltrated samples to evaluate the mechanical properties. The un-infiltrated sample had 2.98GPa hardness, while bronze infiltrated sample had 4.00GPa hardness using Vickers hardness method. Generally, it was found that infiltration of bronze into structural amorphous metal improved homogeneity of the material, as well as the mechanical properties. Further research needs to be done on the mechanical properties of binder-jet printed parts of SAM alloy, infiltrated with bronze. Variation of thickness needs to be included for further research to ascertain the critical achievable depth of infiltration using bronze as the reinforcement material.