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

Cooke, Gary A.; Pestovich, John A.; Huber, Heinz J.

This report presents the results for solid phase characterization (SPC) of solid samples removed from tank 241-C-108 (C-108) on August 12-13,2012, using the off-riser sampler. Samples were received at the 222-S Laboratory on August 13 and were described and photographed. The SPC analyses that were performed include scanning electron microscopy (SEM) using the ASPEX(R)l scanning electron microscope, X-ray diffraction (XRD) using the Rigaku(R) 2 MiniFlex X-ray diffractometer, and polarized light microscopy (PLM) using the Nikon(R) 3 Eclipse Pol optical microscope. The SEM is equipped with an energy dispersive X-ray spectrometer (EDS) to provide chemical information. Gary A. Cooke conducted themore » SEM analysis, John A. Pestovich performed the XRD analysis, and Dr. Heinz J. Huber performed the PLM examination. The results of these analyses are presented here.« less

A conceptual design study for a two-dimensional, electronically scanned thinned array radiometer

NASA Technical Reports Server (NTRS)

Mutton, Philip; Chromik, Christopher C.; Dixon, Iain; Statham, Richard B.; Stillwagen, Frederic H.; Vontheumer, Alfred E.; Sasamoto, Washito A.; Garn, Paul A.; Cosgrove, Patrick A.; Ganoe, George G.

1993-01-01

A conceptual design for the Two-Dimensional, Electronically Steered Thinned Array Radiometer (ESTAR) is described. This instrument is a synthetic aperture microwave radiometer that operates in the L-band frequency range for the measurement of soil moisture and ocean salinity. Two auxiliary instruments, an 8-12 micron, scanning infrared radiometer and a 0.4-1.0 micron, charge coupled device (CCD) video camera, are included to provided data for sea surface temperature measurements and spatial registration of targets respectively. The science requirements were defined by Goddard Space Flight Center. Instrument and the spacecraft configurations are described for missions using the Pegasus and Taurus launch vehicles. The analyses and design trades described include: estimations of size, mass and power, instrument viewing coverage, mechanical design trades, structural and thermal analyses, data and communications performance assessments, and cost estimation.

Forensic tools for the diagnosis of electrocution death: Case study and literature review.

PubMed

Mondello, Cristina; Micali, Antonio; Cardia, Luigi; Argo, Antonina; Zerbo, Stefania; Spagnolo, Elvira Ventura

2018-06-01

Diagnosis of death by electrocution may be difficult when electric marking is not visible or unclear. Accordingly, the body of a man who appeared to have died from accidental electrocution was carefully forensically analysed. Macroscopic and microscopic analysis of the current mark was carried out using a variable-pressure scanning electron microscope equipped with energy dispersive X-ray microanalyser to highlight skin metallisation, indicating the presence of iron and zinc. The histological findings of electrocution myocardial damage were supported by the results of biochemical analysis which demonstrated the creatine kinase-MB and cardiac troponin I elevation. The effects of electric current flow were also highlighted by perforations of endothelial surface of a pulmonary artery using scanning electron microscope, and all the results were analysed by the main tools suggested in the literature.

Synthesis of irregular graphene oxide tubes using green chemistry and their potential use as reinforcement materials for biomedical applications.

PubMed

Serrano-Aroca, Ángel; Deb, Sanjukta

2017-01-01

Micrometer length tubes of graphene oxide (GO) with irregular form were synthesised following facile and green metal complexation reactions. These materials were obtained by crosslinking of GO with calcium, zinc or strontium chlorides at three different temperatures (24, 34 and 55°C) using distilled water as solvent for the compounds and following a remarkably simple and low-cost synthetic method, which employs no hazardous substances and is conducted without consumption of thermal or sonic energy. These irregular continuous GO networks showed a very particular interconnected structure by Field Emission Scanning Electron Microscopy with Energy-Disperse X-Ray Spectroscopy for elemental analysis and High-resolution Transmission Electron Microscopy with Scanning Transmission Electron Microscope Dark Field Imaging, and were analysed by Raman Spectroscopy. To demonstrate the potential use of these 3D GO networks as reinforcement materials for biomedical applications, two composites of calcium alginate with irregular tubes of GO and with single GO nanosheets were prepared with the same amount of GO and divalent atoms and analysed. Thus, the dynamic-mechanical modulus of the composites synthesised with the 3D crosslinked GO networks showed a very significant mechanical improvement due to marked microstructural changes confirmed by confocal microscopy, differential scanning calorimetry and Fourier transform infrared spectroscopy.

Silicifying Biofilm Exopolymers on a Hot-Spring Microstromatolite: Templating Nanometer-Thick Laminae

NASA Astrophysics Data System (ADS)

Handley, Kim M.; Turner, Sue J.; Campbell, Kathleen A.; Mountain, Bruce W.

2008-08-01

Exopolymeric substances (EPS) are an integral component of microbial biofilms; however, few studies have addressed their silicification and preservation in hot-spring deposits. Through comparative analyses with the use of a range of microscopy techniques, we identified abundant EPS significant to the textural development of spicular, microstromatolitic, siliceous sinter at Champagne Pool, Waiotapu, New Zealand. Examination of biofilms coating sinter surfaces by confocal laser scanning microscopy (CLSM), environmental scanning electron microscopy (ESEM), cryo-scanning electron microscopy (cryo-SEM), and transmission electron microscopy (TEM) revealed contraction of the gelatinous EPS matrix into films (approximately 10 nm thick) or fibrillar structures, which is common in conventional SEM analyses and analogous to products of naturally occurring desiccation. Silicification of fibrillar EPS contributed to the formation of filamentous sinter. Matrix surfaces or dehydrated films templated sinter laminae (nanometers to microns thick) that, in places, preserved fenestral voids beneath. Laminae of similar thickness are, in general, common to spicular geyserites. This is the first report to demonstrate EPS templation of siliceous stromatolite laminae. Considering the ubiquity of biofilms on surfaces in hot-spring environments, EPS silicification studies are likely to be important to a better understanding of the origins of laminae in other modern and ancient stromatolitic sinters, and EPS potentially may serve as biosignatures in extraterrestrial rocks.

Synthesis of irregular graphene oxide tubes using green chemistry and their potential use as reinforcement materials for biomedical applications

PubMed Central

Deb, Sanjukta

2017-01-01

Micrometer length tubes of graphene oxide (GO) with irregular form were synthesised following facile and green metal complexation reactions. These materials were obtained by crosslinking of GO with calcium, zinc or strontium chlorides at three different temperatures (24, 34 and 55°C) using distilled water as solvent for the compounds and following a remarkably simple and low-cost synthetic method, which employs no hazardous substances and is conducted without consumption of thermal or sonic energy. These irregular continuous GO networks showed a very particular interconnected structure by Field Emission Scanning Electron Microscopy with Energy-Disperse X-Ray Spectroscopy for elemental analysis and High-resolution Transmission Electron Microscopy with Scanning Transmission Electron Microscope Dark Field Imaging, and were analysed by Raman Spectroscopy. To demonstrate the potential use of these 3D GO networks as reinforcement materials for biomedical applications, two composites of calcium alginate with irregular tubes of GO and with single GO nanosheets were prepared with the same amount of GO and divalent atoms and analysed. Thus, the dynamic-mechanical modulus of the composites synthesised with the 3D crosslinked GO networks showed a very significant mechanical improvement due to marked microstructural changes confirmed by confocal microscopy, differential scanning calorimetry and Fourier transform infrared spectroscopy. PMID:28934354

HANFORD WASTE MINERALOGY REFERENCE REPORT

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

DISSELKAMP RS

2010-06-29

This report lists the observed mineral phases present in the Hanford tanks. This task was accomplished by performing a review of numerous reports that used experimental techniques including, but not limited to: x-ray diffraction, polarized light microscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, electron energy loss spectroscopy, and particle size distribution analyses. This report contains tables that can be used as a quick reference to identify the crystal phases observed in Hanford waste.

HANFORD WASTE MINEROLOGY REFERENCE REPORT

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

DISSELKAMP RS

2010-06-18

This report lists the observed mineral phase phases present in the Hanford tanks. This task was accomplished by performing a review of numerous reports using experimental techniques including, but not limited to: x-ray diffraction, polarized light microscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, electron energy loss spectroscopy, and particle size distribution analyses. This report contains tables that can be used as a quick reference to identify the crystal phases present observed in Hanford waste.

Realization of a four-step molecular switch in scanning tunneling microscope manipulation of single chlorophyll-a molecules

PubMed Central

Iancu, Violeta; Hla, Saw-Wai

2006-01-01

Single chlorophyll-a molecules, a vital resource for the sustenance of life on Earth, have been investigated by using scanning tunneling microscope manipulation and spectroscopy on a gold substrate at 4.6 K. Chlorophyll-a binds on Au(111) via its porphyrin unit while the phytyl-chain is elevated from the surface by the support of four CH3 groups. By injecting tunneling electrons from the scanning tunneling microscope tip, we are able to bend the phytyl-chain, which enables the switching of four molecular conformations in a controlled manner. Statistical analyses and structural calculations reveal that all reversible switching mechanisms are initiated by a single tunneling-electron energy-transfer process, which induces bond rotation within the phytyl-chain. PMID:16954201

Morphology of glochidia of Lampsilis higginsi (Bivalvia: Unionidae) compared with three related species

USGS Publications Warehouse

Waller, D.L.; Holland Bartels, L. E.; Mitchell, L.G.

1988-01-01

Glochidia of the endangered unionid mussel Lampsilis higginsi (Lea) are morphologically similar to those of several other species in the upper Mississippi River. Life history details, such as the timing of reproduction and identity of host fish, can be readily studied if the glochidia of L. higginsi can be distinguished from those of related species. Authors used light and scanning electron microscopy and statistical analyses of three shell measurements, shell length, shell height, and hinge length, to compare the glochidia of L. higginsi with those of L. radiata siliquoidea (Barnes), L. ventricosa (Barnes), and Ligumia recta (Lamarck). Glochidia of L. higginsi were differentiated by scanning electron microscopy on the basis of a combined examination of the position of the hinge ligament and the width of dorsal ridges, but were indistinguishable by light microscope examination or by statistical analyses of measurements.

Chemical synthesis of oriented ferromagnetic LaSr-2 × 4 manganese oxide molecular sieve nanowires

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

Carretero-Genevrier, Adrián; Gazquez, Jaume; Magen, Cesar

2012-04-25

Here we report a chemical solution based method using nanoporous track-etched polymer templates for producing long and oriented LaSr-2 × 4 manganese oxide molecular sieve nanowires. Scanning transmission electron microscopy and electron energy loss spectroscopy analyses show that the nanowires are ferromagnetic at room temperature, single crystalline, epitaxially grown and self-aligned.

An endolithic microbial community in dolomite rock in central Switzerland: characterization by reflection spectroscopy, pigment analyses, scanning electron microscopy, and laser scanning microscopy.

PubMed

Horath, T; Neu, T R; Bachofen, R

2006-04-01

A community of endolithic microorganisms dominated by phototrophs was found as a distinct band a few millimeters below the surface of bare exposed dolomite rocks in the Piora Valley in the Alps. Using in situ reflectance spectroscopy, we detected chlorophyll a (Chl a), phycobilins, carotenoids, and an unknown type of bacteriochlorophyll-like pigment absorbing in vivo at about 720 nm. In cross sections, the data indicated a defined distribution of different groups of organisms perpendicular to the rock surface. High-performance liquid chromatography analyses of pigments extracted with organic solvents confirmed the presence of two types of bacteriochlorophylls besides chlorophylls and various carotenoids. Spherical organisms of varying sizes and small filaments were observed in situ with scanning electron microscopy and confocal laser scanning microscopy (one- and two-photon technique). The latter allowed visualization of the distribution of phototrophic microorganisms by the autofluorescence of their pigments within the rock. Coccoid cyanobacteria of various sizes predominated over filamentous ones. Application of fluorescence-labeled lectins demonstrated that most cyanobacteria were embedded in an exopolymeric matrix. Nucleic acid stains revealed a wide distribution of small heterotrophs. Some biological structures emitting a green autofluorescence remain to be identified.

Analysis of liquid suspensions using scanning electron microscopy in transmission: estimation of the water film thickness using Monte-Carlo simulations.

PubMed

Xiao, J; Foray, G; Masenelli-Varlot, K

2018-02-01

Environmental scanning electron microscopy (ESEM) allows the observation of liquids under specific conditions of pressure and temperature. Moreover, when working in the transmission mode, that is in scanning transmission electron microscopy (STEM), nano-objects can be analysed inside a liquid. The contrast in the images is mass-thickness dependent as in STEM-in-TEM (transmission electron microscopy) using closed cells. However, in STEM-in-ESEM, as the liquid-vapour equilibrium is kept dynamically, the thickness of the water droplet remains unknown. In this paper, the contrasts measured in the experimental images are compared with calculations using Monte-Carlo simulations in order to estimate the thickness of water. Two examples are given. On gold nanoparticles, the thickness of a thick film can be estimated thanks to a contrast inversion. On core-shell latex particles, the grey level of the shell compared with those of the core and of the water film gives a relatively precise measurement of the water film thickness. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Synthesis, spectroscopic, thermal and anticancer studies of metal-antibiotic chelations: Ca(II), Fe(III), Pd(II) and Au(III) chloramphenicol complexes

NASA Astrophysics Data System (ADS)

Al-Khodir, Fatima A. I.; Refat, Moamen S.

2016-09-01

Four Ca(II), Fe(III), Pd(II) and Au(III) complexes of chloramphenicol drug have been synthesized and well characterized using elemental analyses, (infrared, electronic, and 1H-NMR) spectra, magnetic susceptibility measurement, and thermal analyses. Infrared spectral data show that the chloramphenicol drug coordinated to Ca(II), Pd(II) and Au(III) metal ions through two hydroxyl groups with 1:1 or 1:2 M ratios, but Fe(III) ions chelated towards chloramphenicol drug via the oxygen and nitrogen atoms of amide group with 1:2 ratio based on presence of keto↔enol form. The X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) techniques were used to identify the nano-size particles of both iron(III) and gold(III) chloramphenicol complexes. The antimicrobial assessments of the chloramphenicol complexes were scanned and collected the results against of some kind of bacteria and fungi. The cytotoxic activity of the gold(III) complex was tested against the human colon carcinoma (HCT-116) and human hepatocellular carcinoma (HepG-2) tumor cell lines.

Electron Beam/Laser Glazing of Iron-Base Materials.

DTIC Science & Technology

1981-07-01

alloy (-l. 5wt %Cr) steels after laser and electron beam glazing. In this work it is shown that the dramatic difference in microstructure and hardness...highly alloyed tool steels can be critical in determining the complexity of the solidification route. The analyses of M2, M42 and M7 are given in...the type described in Fe- Ni alloys (1). This con- clusion is based on optical and scanning electron microscope observation unambig- uously showing

Optimizing use of the structural chemical analyser (variable pressure FESEM-EDX Raman spectroscopy) on micro-size complex historical paintings characterization.

PubMed

Guerra, I; Cardell, C

2015-10-01

The novel Structural Chemical Analyser (hyphenated Raman spectroscopy and scanning electron microscopy equipped with an X-ray detector) is gaining popularity since it allows 3-D morphological studies and elemental, molecular, structural and electronic analyses of a single complex micro-sized sample without transfer between instruments. However, its full potential remains unexploited in painting heritage where simultaneous identification of inorganic and organic materials in paintings is critically yet unresolved. Despite benefits and drawbacks shown in literature, new challenges have to be faced analysing multifaceted paint specimens. SEM-Structural Chemical Analyser systems differ since they are fabricated ad hoc by request. As configuration influences the procedure to optimize analyses, likewise analytical protocols have to be designed ad hoc. This paper deals with the optimization of the analytical procedure of a Variable Pressure Field Emission scanning electron microscopy equipped with an X-ray detector Raman spectroscopy system to analyse historical paint samples. We address essential parameters, technical challenges and limitations raised from analysing paint stratigraphies, archaeological samples and loose pigments. We show that accurate data interpretation requires comprehensive knowledge of factors affecting Raman spectra. We tackled: (i) the in-FESEM-Raman spectroscopy analytical sequence, (ii) correlations between FESEM and Structural Chemical Analyser/laser analytical position, (iii) Raman signal intensity under different VP-FESEM vacuum modes, (iv) carbon deposition on samples under FESEM low-vacuum mode, (v) crystal nature and morphology, (vi) depth of focus and (vii) surface-enhanced Raman scattering effect. We recommend careful planning of analysis strategies prior to research which, although time consuming, guarantees reliable results. The ultimate goal of this paper is to help to guide future users of a FESEM-Structural Chemical Analyser system in order to increase applications. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Miniaturized Environmental Scanning Electron Microscope for In Situ Planetary Studies

NASA Technical Reports Server (NTRS)

Gaskin, Jessica; Abbott, Terry; Medley, Stephanie; Gregory, Don; Thaisen, Kevin; Taylor , Lawrence; Ramsey, Brian; Jerman, Gregory; Sampson, Allen; Harvey, Ralph

2010-01-01

The exploration of remote planetary surfaces calls for the advancement of low power, highly-miniaturized instrumentation. Instruments of this nature that are capable of multiple types of analyses will prove to be particularly useful as we prepare for human return to the moon, and as we continue to explore increasingly remote locations in our Solar System. To this end, our group has been developing a miniaturized Environmental-Scanning Electron Microscope (mESEM) capable of remote investigations of mineralogical samples through in-situ topographical and chemical analysis on a fine scale. The functioning of an SEM is well known: an electron beam is focused to nanometer-scale onto a given sample where resulting emissions such as backscattered and secondary electrons, X-rays, and visible light are registered. Raster scanning the primary electron beam across the sample then gives a fine-scale image of the surface topography (texture), crystalline structure and orientation, with accompanying elemental composition. The flexibility in the types of measurements the mESEM is capable of, makes it ideally suited for a variety of applications. The mESEM is appropriate for use on multiple planetary surfaces, and for a variety of mission goals (from science to non-destructive analysis to ISRU). We will identify potential applications and range of potential uses related to planetary exploration. Over the past few of years we have initiated fabrication and testing of a proof-of-concept assembly, consisting of a cold-field-emission electron gun and custom high-voltage power supply, electrostatic electron-beam focusing column, and scanning-imaging electronics plus backscatter detector. Current project status will be discussed. This effort is funded through the NASA Research Opportunities in Space and Earth Sciences - Planetary Instrument Definition and Development Program.

Flexible foils formed by a prolonged electron beam irradiation in scanning electron microscope

NASA Astrophysics Data System (ADS)

Čechal, Jan; Šikola, Tomáš

2017-11-01

The ubiquitous presence of hydrocarbon contamination on solid surfaces alters their inherent physical properties and complicates the surface analyses. An irradiation of sample surface with electron beam can lead to the chemical transformation of the hydrocarbon layer to carbon films, which are flexible and capable of acting as a barrier for chemical etching of an underlying material. The growth of these foils is limited by supply of hydrocarbons to the writing beam position rather than the electron dose or electron beam current. The prepared films can find their applications in fabrication of surface nanostructures without a need of an electron sensitive resist material.

Quantitative fractography by digital image processing: NIH Image macro tools for stereo pair analysis and 3-D reconstruction.

PubMed

Hein, L R

2001-10-01

A set of NIH Image macro programs was developed to make qualitative and quantitative analyses from digital stereo pictures produced by scanning electron microscopes. These tools were designed for image alignment, anaglyph representation, animation, reconstruction of true elevation surfaces, reconstruction of elevation profiles, true-scale elevation mapping and, for the quantitative approach, surface area and roughness calculations. Limitations on time processing, scanning techniques and programming concepts are also discussed.

Detection of titanium in human tissues after craniofacial surgery.

PubMed

Jorgenson, D S; Mayer, M H; Ellenbogen, R G; Centeno, J A; Johnson, F B; Mullick, F G; Manson, P N

1997-04-01

Generally, titanium fixation plates are not removed after osteosynthesis, because they have high biocompatability and high corrosion resistance characteristics. Experiments with laboratory animals, and limited studies of analyses of human tissues, have reported evidence of titanium release into local and distant tissues. This study summarizes our results of the analysis of soft tissues for titanium in four patients with titanium microfixation plates. Energy dispersive x-ray analysis, scanning electron microscopy, and electrothermal atomic absorption spectrophotometry were used to detect trace amounts of titanium in surrounding soft tissues. A single metal inclusion was detected by scanning electron microscopy and energy dispersive x-ray analysis in one patient, whereas, electrothermal atomic absorption spectrophotometry analyses revealed titanium present in three of four specimens in levels ranging from 7.92 to 31.8 micrograms/gm of dry tissue. Results from this study revealed trace amounts of titanium in tissues surrounding craniofacial plates. At the atomic level, electrothermal atomic absorption spectrophotometry appears to be a sensitive tool to quantitatively detect ultra-trace amounts of metal in human tissue.

Systematic analyses of vibration noise of a vibration isolation system for high-resolution scanning tunneling microscopes.

PubMed

Iwaya, Katsuya; Shimizu, Ryota; Hashizume, Tomihiro; Hitosugi, Taro

2011-08-01

We designed and constructed an effective vibration isolation system for stable scanning tunneling microscopy measurements using a separate foundation and two vibration isolation stages (i.e., a combination of passive and active vibration isolation dampers). Systematic analyses of vibration data along the horizontal and vertical directions are present, including the vibration transfer functions of each stage and the overall vibration isolation system. To demonstrate the performance of the system, tunneling current noise measurements are conducted with and without the vibration isolation. Combining passive and active vibration isolation dampers successfully removes most of the vibration noise in the tunneling current up to 100 Hz. These comprehensive vibration noise data, along with details of the entire system, can be used to establish a clear guideline for building an effective vibration isolation system for various scanning probe microscopes and electron microscopes.

Scanning electron microscopy and X-ray energy dispersive spectroscopy - useful tools in the analysis of pharmaceutical products

NASA Astrophysics Data System (ADS)

Sarecka-Hujar, Beata; Balwierz, Radoslaw; Ostrozka-Cieslik, Aneta; Dyja, Renata; Lukowiec, Dariusz; Jankowski, Andrzej

2017-11-01

The quality of the drug, its purity and identification of degradation products provide the highest quality of pharmaceutical products. The energy dispersive spectroscopy (EDS) method analyses the percentage of each element form as well as their distribution, and morphological characteristics of the drug form. We analysed the usefulness of EDS method in testing orally disintegrating tablets (ODT) with trimetazidine hydrochloride with high resolution scanning electron microscopy (SEM, SUPRA25 Carl Zeiss company) with spectrophotometer equipped with an X-ray energy dispersion (EDAX Company). The samples of the analysed tablets were imaged after applying conductive layers of gold on their surface. In the EDS analysis the compositions of each sample of the obtained tablets were observed to be virtually identical. The differences in the content of carbon and oxygen came from differences in the composition of particular tablets. The presence of gold in the composition resulted from the sputtering the surface of tablets with gold during the analysis. Knowing the composition of the tablet, SEM-EDS method helps to locate and identify the impurities and degradation products of the compounds, leading to a better understanding of the mechanisms of their formation.

Cement lines of secondary osteons in human bone are not mineral-deficient: new data in a historical perspective.

PubMed

Skedros, John G; Holmes, Jennifer L; Vajda, Eric G; Bloebaum, Roy D

2005-09-01

Using qualitative backscattered electron (BSE) imaging and quantitative energy dispersive X-ray (EDX) spectroscopy, some investigators have concluded that cement (reversal) lines located at the periphery of secondary osteons are poorly mineralized viscous interfaces with respect to surrounding bone. This conclusion contradicts historical observations of apparent highly mineralized (or collagen-deficient) cement lines in microradiographs. Such conclusions, however, may stem from unrecognized artifacts that can occur during scanning electron microscopy. These include specimen degradation due to high-energy beams and the sampling of electron interaction volumes that extend beyond target locations during EDX analysis. This study used quantitative BSE imaging and EDX analysis, each with relatively lower-energy beams, to test the hypothesis that cement lines are poorly mineralized. Undemineralized adult human femoral diaphyses (n = 8) and radial diaphyses (n = 5) were sectioned transversely, embedded in polymethyl methacrylate, and imaged in a scanning electron microscope for BSE and EDX analyses. Unembedded samples were also evaluated. Additional thin embedded samples were stained and evaluated with light microscopy and correlated BSE imaging. BSE analyses showed the consistent presence of a bright line (higher atomic number) coincident with the classical location and description of the cement line. This may represent relative hypermineralization or, alternatively, collagen deficiency with respect to surrounding bone. EDX analyses of cement lines showed either higher Ca content or equivalent Ca content when compared to distant osteonal and interstitial bone. These data reject the hypothesis that cement lines of secondary osteons are poorly mineralized. Copyright 2005 Wiley-Liss, Inc

Total-scattering pair-distribution function of organic material from powder electron diffraction data.

PubMed

Gorelik, Tatiana E; Schmidt, Martin U; Kolb, Ute; Billinge, Simon J L

2015-04-01

This paper shows that pair-distribution function (PDF) analyses can be carried out on organic and organometallic compounds from powder electron diffraction data. Different experimental setups are demonstrated, including selected area electron diffraction and nanodiffraction in transmission electron microscopy or nanodiffraction in scanning transmission electron microscopy modes. The methods were demonstrated on organometallic complexes (chlorinated and unchlorinated copper phthalocyanine) and on purely organic compounds (quinacridone). The PDF curves from powder electron diffraction data, called ePDF, are in good agreement with PDF curves determined from X-ray powder data demonstrating that the problems of obtaining kinematical scattering data and avoiding beam damage of the sample are possible to resolve.

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

McCormac, Kathleen; Byrd, Ian; Brannen, Rodney

We prepared highly porous Si/TiO 2 composite nanofibres using a unique sulphur-templating method combined with electrospinning. The structure, morphology, surface area, phase and composition of these nanofibres were characterized using Raman spectroscopy, scanning electron microscopy, powder X-ray diffraction, surface area analyser and thermogravimetric analyser. The specific surface area of Si/TiO 2 porous NFs is as large as 387m 2g -1, whose silicon capacity can be maintained above 1580mAhg -1 in 180 cycles.

Thickness dependence of scattering cross-sections in quantitative scanning transmission electron microscopy.

PubMed

Martinez, G T; van den Bos, K H W; Alania, M; Nellist, P D; Van Aert, S

2018-04-01

In quantitative scanning transmission electron microscopy (STEM), scattering cross-sections have been shown to be very sensitive to the number of atoms in a column and its composition. They correspond to the integrated intensity over the atomic column and they outperform other measures. As compared to atomic column peak intensities, which saturate at a given thickness, scattering cross-sections increase monotonically. A study of the electron wave propagation is presented to explain the sensitivity of the scattering cross-sections. Based on the multislice algorithm, we analyse the wave propagation inside the crystal and its link to the scattered signal for the different probe positions contained in the scattering cross-section for detector collection in the low-, middle- and high-angle regimes. The influence to the signal from scattering of neighbouring columns is also discussed. Copyright © 2018 Elsevier B.V. All rights reserved.

Characterizing the residual glass in a MgO/Al2O3/SiO2/ZrO2/Y2O3 glass-ceramic

PubMed Central

Seidel, Sabrina; Patzig, Christian; Wisniewski, Wolfgang; Gawronski, Antje; Hu, Yongfeng; Höche, Thomas; Rüssel, Christian

2016-01-01

The non-isochemical crystallization of glasses leads to glass-ceramics in which the chemical composition of the amorphous matrix differs from that of the parent glass. It is challenging to solely analyse the properties of these residual glassy phases because they frequently contain finely dispersed crystals. In this study, the composition of the residual glass matrix after the crystallization of a glass with the mol% composition 50.6 SiO2 · 20.7 MgO · 20.7 Al2O3 · 5.6 ZrO2 · 2.4 Y2O3 is analysed by scanning transmission electron microscopy (STEM) including energy dispersive X-ray analysis (EDXS). A batch of the residual glass with the determined composition is subsequently melted and selected properties are analysed. Furthermore, the crystallization behaviour of this residual glass is studied by X-ray diffraction, scanning electron microscopy including electron backscatter diffraction and STEM-EDXS analyses. The residual glass shows sole surface crystallization of indialite and multiple yttrium silicates while bulk nucleation does not occur. This is in contrast to the crystallization behaviour of the parent glass, in which a predominant bulk nucleation of spinel and ZrO2 is observed. The crystallization of the residual glass probably leads to different crystalline phases when it is in contact to air, rather than when it is enclosed within the microstructure of the parent glass-ceramics. PMID:27734918

Oscheius wisconsinensis n. sp. (Nematoda: Rhabditidae), a potential entomopathogenic nematode from the marshlands of Wisconsin

USDA-ARS?s Scientific Manuscript database

Oscheius wisconsinensis n. sp. (Rhabditidae) was recovered through the Galleria bait method from a wild cranberry marsh in Jackson County, Wisconsin, USA. Morphological studies with light microscopy and scanning electron microscopy, as well as molecular analyses of the near-full-length small subunit...

Photosynthetic microorganism-mediated synthesis of akaganeite (beta-FeOOH) nanorods.

PubMed

Brayner, Roberta; Yéprémian, Claude; Djediat, Chakib; Coradin, Thibaud; Herbst, Fréderic; Livage, Jacques; Fiévet, Fernand; Couté, Alain

2009-09-01

Common Anabaena and Calothrix cyanobacteria and Klebsormidium green algae are shown to form intracellularly akaganeite beta-FeOOH nanorods of well-controlled size and unusual morphology at room temperature. X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy X-ray energy dispersive spectrometry (SEM-EDS) analyses are used to investigate particle structure, size, and morphology. A mechanism involving iron-siderophore complex formation is proposed and compared with iron biomineralization in magnetotactic bacteria.

Electron tomography and cryo-SEM characterization reveals novel ultrastructural features of host-parasite interaction during Chlamydia abortus infection.

PubMed

Wilkat, M; Herdoiza, E; Forsbach-Birk, V; Walther, P; Essig, A

2014-08-01

Chlamydia (C.) abortus is a widely spread pathogen among ruminants that can be transmitted to women during pregnancy leading to severe systemic infection with consecutive abortion. As a member of the Chlamydiaceae, C. abortus shares the characteristic feature of an obligate intracellular biphasic developmental cycle with two morphological forms including elementary bodies (EBs) and reticulate bodies (RBs). In contrast to other chlamydial species, C. abortus ultrastructure has not been investigated yet. To do so, samples were fixed by high-pressure freezing and processed by different electron microscopic methods. Freeze-substituted samples were analysed by transmission electron microscopy, scanning transmission electron microscopical tomography and immuno-electron microscopy, and freeze-fractured samples were analysed by cryo-scanning electron microscopy. Here, we present three ultrastructural features of C. abortus that have not been reported up to now. Firstly, the morphological evidence that C. abortus is equipped with the type three secretion system. Secondly, the accumulation and even coating of whole inclusion bodies by membrane complexes consisting of multiple closely adjacent membranes which seems to be a C. abortus specific feature. Thirdly, the formation of small vesicles in the periplasmic space of RBs in the second half of the developmental cycle. Concerning the time point of their formation and the fact that they harbour chlamydial components, these vesicles might be morphological correlates of an intermediate step during the process of redifferentiation of RBs into EBs. As this feature has also been shown for C. trachomatis and C. pneumoniae, it might be a common characteristic of the family of Chlamydiaceae.

Highly patterned growth of SnO2 nanowires using a sub-atmospheric vapor-liquid-solid deposition

NASA Astrophysics Data System (ADS)

Akbari, M.; Mohajerzadeh, S.

2017-08-01

We report the realization of tin-oxide nanowires on patterned structures using a vapor-liquid-solid (VLS) process. While gold acts as the catalyst for the growth of wires, a tin-oxide containing sol-gel solution is spin coated on silicon substrate to act as the source for SnO vapor. The growth of tin-oxide nano-structures occurs mostly at the vicinity of the pre-deposited solution. By patterning the gold as the catalyst material, one is able to observe the growth at desired places. The growth of nanowires is highly dense within 100 µm away from such in situ source and their length is of the order of 5 µm. By further distancing from the source, the growth becomes more limited and nanowires become shorter and more sparsely distributed. The growth of nanowires has been studied using scanning and transmission electron microscopy tools while their composition has been investigated using XRD and EDS analyses. As a novel application, we have employed the grown nanowires as electron detection elements to measure the emitted electrons from electron sources. This configuration can be further used as electron detectors for scanning electron microscopes.

HAADF-STEM atom counting in atom probe tomography specimens: Towards quantitative correlative microscopy.

PubMed

Lefebvre, W; Hernandez-Maldonado, D; Moyon, F; Cuvilly, F; Vaudolon, C; Shinde, D; Vurpillot, F

2015-12-01

The geometry of atom probe tomography tips strongly differs from standard scanning transmission electron microscopy foils. Whereas the later are rather flat and thin (<20 nm), tips display a curved surface and a significantly larger thickness. As far as a correlative approach aims at analysing the same specimen by both techniques, it is mandatory to explore the limits and advantages imposed by the particular geometry of atom probe tomography specimens. Based on simulations (electron probe propagation and image simulations), the possibility to apply quantitative high angle annular dark field scanning transmission electron microscopy to of atom probe tomography specimens has been tested. The influence of electron probe convergence and the benefice of deconvolution of electron probe point spread function electron have been established. Atom counting in atom probe tomography specimens is for the first time reported in this present work. It is demonstrated that, based on single projections of high angle annular dark field imaging, significant quantitative information can be used as additional input for refining the data obtained by correlative analysis of the specimen in APT, therefore opening new perspectives in the field of atomic scale tomography. Copyright © 2015 Elsevier B.V. All rights reserved.

Tailoring oxidation of aluminum nanoparticles reinforced with carbon nanotubes

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

Sharma, Manjula; Sharma, Vimal, E-mail: manjula.physics@gmail.com

2016-05-23

In this report, the oxidation temperature and reaction enthalpy of Aluminum (Al) nanoparticles has been controlled by reinforcing with carbon nanotubes. The physical mixing method with ultrasonication was employed to synthesize CNT/Al nanocomposite powders. The micro-morphology of nanoconmposite powders has been analysed by scanning electron microscopy, energy dispersive spectroscopy, Raman spectroscopy and X-ray diffraction techniques. The oxidation behavior of nanocomposite powders analyzed by thermogravimetry/differential scanning calorimertry showed improvement in the exothermic enthalpy. Largest exothermic enthalpy of-1251J/g was observed for CNT (4 wt%)/Al nanocomposite.

Total-scattering pair-distribution function of organic material from powder electron diffraction data

DOE PAGES

Gorelik, Tatiana E.; Billinge, Simon J. L.; Schmidt, Martin U.; ...

2015-04-01

This paper shows for the first time that pair-distribution function analyses can be carried out on organic and organo-metallic compounds from powder electron diffraction data. Different experimental setups are demonstrated, including selected area electron diffraction (SAED) and nanodiffraction in transmission electron microscopy (TEM) or nanodiffraction in scanning transmission electron microscopy (STEM) modes. The methods were demonstrated on organo-metallic complexes (chlorinated and unchlorinated copper-phthalocyanine) and on purely organic compounds (quinacridone). The PDF curves from powder electron diffraction data, called ePDF, are in good agreement with PDF curves determined from X-ray powder data demonstrating that the problems of obtaining kinematical scattering datamore » and avoiding beam-damage of the sample are possible to resolve.« less

Tannin bark Melalauca cajuputi powell (gelam) as green corrosion inhibitor of mild steel

NASA Astrophysics Data System (ADS)

Talib, Nur Atiqah Abu; Zakaria, Sarani; Hua, Chia Chin; Othman, Norinsan Kamil

2014-09-01

Tannin was extracted from gelam bark and used to produce corrosion inhibitor for mild steel. Tannin was extracted from gelam bark using 70% aqueous acetone for 6 hour. Tannin powder was characterization using fourier transform infrared spectroscopy to analyse chemical component in tannin and Scanning electron microscope (SEM) for tannin physical structure. The tannin effect on the corrosion inhibition of mild steel has been investigated in 1Mol HCl solution for 6 hour followed ASTM. The weight loss method were applied to study the mild steel corrosion behavior in the present and absend of different concentration of tannin (250, 300, 350)ppm. Tannin act good inhibitor as corrosion inhibitor for mild steel in acid medium. Surface morphology of carbon steel with and without inhibitor was investigated by scanning electron microscopy.

Metallurgical characterization of a new nickel-titanium wire for rotary endodontic instruments.

PubMed

Alapati, Satish B; Brantley, William A; Iijima, Masahiro; Clark, William A T; Kovarik, Libor; Buie, Caesar; Liu, Jie; Ben Johnson, William

2009-11-01

A novel thermomechanical processing procedure has been developed that yields a superelastic (SE) nickel-titanium (NiTi) wire (M-Wire) that laboratory testing shows has improved mechanical properties compared with conventional SE austenitic NiTi wires used for manufacture of rotary instruments. The objective of this study was to determine the origin of the improved mechanical properties. Specimens from 2 batches of M-Wire prepared under different processing conditions and from 1 batch of standard-processed SE wire for rotary instruments were examined by scanning transmission electron microscopy, temperature-modulated differential scanning calorimetry, micro-x-ray diffraction, and scanning electron microscopy with x-ray energy-dispersive spectrometric analyses. The processing for M-Wire yields a microstructure containing martensite, that the proportions of NiTi phases depend on processing conditions, and that the microstructure exhibits pronounced evidence of alloy strengthening. The presence of Ti(2)Ni precipitates in both microstructures indicates that M-Wire and the conventional SE wire for rotary instruments are titanium-rich.

Characterisation of Oscheius onirici (Nematoda: Rhabditidae), a hermaphroditic nematode from the marshlands of Wisconsin

USDA-ARS?s Scientific Manuscript database

An Oscheius (Rhabditidae) was recovered through the Galleria bait method from a wild cranberry marsh in Jackson County, Wisconsin, USA. Morphological studies with light microscopy and scanning electron microscopy, as well as molecular analyses of the near-full-length small subunit rDNA gene (SSU), D...

Differentiation of Aedes aegypti and Aedes notoscriptus (Diptera: Culicidae) eggs using scanning electron microscopy.

PubMed

Faull, Katherine J; Williams, Craig R

2016-05-01

Aedes notoscriptus and Aedes aegypti are both peri-domestic, invasive container-breeding mosquitoes. While the two potential arboviral vectors are bionomically similar, their sympatric distribution in Australia is limited. In this study, analyses of Ae. aegypti and Ae. notoscriptus eggs were enabled using scanning electron microscopy. Significant variations in egg length to width ratio and outer chorionic cell field morphology between Ae. aegypti and Ae. notoscriptus enabled distinction of the two species. Intraspecific variations in cell field morphology also enabled differentiation of the separate populations of both species, highlighting regional and global variation. Our study provides a comprehensive comparative analysis of inter- and intraspecific egg morphological and morphometric variation between two invasive container-breeding mosquitoes. The results indicate a high degree of intraspecific variation in Ae. notoscriptus egg morphology when compared to the eggs of Ae. aegypti. Comparative morphological analyses of Ae. aegypti and Ae. notoscriptus egg attributes using SEM allows differentiation of the species and may be helpful in understanding egg biology in relation to biotope of origin. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantitative and structural analyses of the in vitro and ex vivo biofilm-forming ability of dermatophytes.

PubMed

Brilhante, Raimunda Sâmia Nogueira; Correia, Edmilson Emanuel Monteiro; Guedes, Glaucia Morgana de Melo; Pereira, Vandbergue Santos; Oliveira, Jonathas Sales de; Bandeira, Silviane Praciano; Alencar, Lucas Pereira de; Andrade, Ana Raquel Colares de; Castelo-Branco, Débora de Souza Collares Maia; Cordeiro, Rossana de Aguiar; Pinheiro, Adriana de Queiroz; Chaves, Lúcio Jackson Queiroz; Pereira Neto, Waldemiro de Aquino; Sidrim, José Júlio Costa; Rocha, Marcos Fábio Gadelha

2017-07-01

The aim of this study was to evaluate the in vitro and ex vivo biofilm-forming ability of dermatophytes on a nail fragment. Initially, four isolates of Trichophyton rubrum, six of Trichophyton tonsurans, three of Trichophyton mentagrophytes, ten of Microsporum canis and three of Microsporum gypseum were tested for production biomass by crystal violet assay. Then, one strain per species presenting the best biofilm production was chosen for further studies by optical microscopy (Congo red staining), confocal laser scanning (LIVE/DEAD staining) and scanning electron (secondary electron) microscopy. Biomass quantification by crystal violet assay, optical microscope images of Congo red staining, confocal microscope and scanning electron microscope images revealed that all species studied are able to form biofilms both in vitro and ex vivo, with variable density and architecture. M. gypseum, T. rubrum and T. tonsurans produced robust biofilms, with abundant matrix and biomass, while M. canis produced the weakest biofilms compared to other species. This study sheds light on biofilms of different dermatophyte species, which will contribute to a better understanding of the pathophysiology of dermatophytosis. Further studies of this type are necessary to investigate the processes involved in the formation and composition of dermatophyte biofilms.

Nanoscale observation of the natural structure of milk-fat globules and casein micelles in the liquid condition using a scanning electron assisted dielectric microscopy.

PubMed

Ogura, Toshihiko; Okada, Tomoko

2017-09-30

Recently, aqueous nanoparticles have been used in drug-delivery systems for new type medicines. In particular, milk-casein micelles have been used as drug nanocarriers for targeting cancer cells. Therefore, nanostructure observation of particles and micelles in their native liquid condition is indispensable for analysing their function and mechanisms. However, traditional optical and scanning electron microscopy have difficulty observing the nanostructures of aqueous micelles. Recently, we developed a novel imaging technique called scanning electron-assisted dielectric microscopy (SE-ADM) that enables observation of various biological specimens in water with very little radiation damage and high-contrast imaging without staining or fixation at an 8-nm spatial resolution. In this study, for the first time, we show that the SE-ADM system is capable of high-resolution observation of whole-milk specimens in their natural state. Moreover, we successfully observe the casein micelles and milk-fat globules in an intact liquid condition. Our SE-ADM system can be applied to various biological particles and micelles in a native liquid state. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Crystal growth of carbonate apatite using a CaCO3 flux.

PubMed

Suetsugu, Y; Tanaka, J

1999-09-01

Single crystals of carbonate apatite were grown using a CaCO3 flux under an Ar gas pressure of 55 MPa. The crystals obtained were observed by scanning electron microscopy, optical microscopy and X-ray diffraction. Electron probe microanalyses and thermal analyses were performed. CO3 ions in planar triangle form replaced both OH sites and PO4 tetrahedral sites in the apatite structure: in particular, the OH sites were perfectly substituted by CO3 ions using this method.

Surfactant-Templated Mesoporous Metal Oxide Nanowires

DOE PAGES

Luo, Hongmei; Lin, Qianglu; Baber, Stacy; ...

2010-01-01

We demore » monstrate two approaches to prepare mesoporous metal oxide nanowires by surfactant assembly and nanoconfinement via sol-gel or electrochemical deposition. For example, mesoporous Ta 2 O 5 and zeolite nanowires are prepared by block copolymer Pluronic 123-templated sol-gel method, and mesoporous ZnO nanowires are prepared by electrodeposition in presence of anionic surfactant sodium dodecyl sulfate (SDS) surfactant, in porous membranes. The morphologies of porous nanowires are studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses.« less

In-situ observation of recrystallization in an AlMgScZr alloy using confocal laser scanning microscopy

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

Taendl, J., E-mail: johannes.taendl@tugraz.atl; Nambu, S.; Orthacker, A.

2015-10-15

In this work we present a novel in-situ approach to study the recrystallization behavior of age hardening alloys. We use confocal laser scanning microscopy (CLSM) at 400 °C to investigate the static recrystallization of an AlMg4Sc0.4Zr0.12 alloy in-situ. The results are combined with electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analyses. It was found that CLSM is a powerful tool to visualize both the local initiation and temporal sequence of recrystallization. After fast nucleation and initial growth, the grain growth rate decreases and the grain boundary migration stops after some minutes due to Zener pinning from Al{sub 3}(Sc,Zr)more » precipitates produced during the heat treatment. EBSD and TEM analyses confirm both the boundary movements and the particle-boundary interactions. - Highlights: • First time that CLSM is used to study recrystallization in-situ. • The start and end of recrystallization can be directly observed. • The procedure is easy to apply and requires only simple data interpretation. • In-situ observations on the surface correlate to modifications inside the bulk. • In-situ observations correlate to EBSD and EFTEM analyses.« less

Precipitation in a lead calcium tin anode

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

Perez-Gonzalez, Francisco A., E-mail: fco.aurelio@inbox.com; Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon; Camurri, Carlos G., E-mail: ccamurri@udec.cl

Samples from a hot rolled sheet of a tin and calcium bearing lead alloy were solution heat treated at 300 Degree-Sign C and cooled down to room temperature at different rates; these samples were left at room temperature to study natural precipitation of CaSn{sub 3} particles. The samples were aged for 45 days before analysing their microstructure, which was carried out in a scanning electron microscope using secondary and backscattered electron detectors. Selected X-ray spectra analyses were conducted to verify the nature of the precipitates. Images were taken at different magnifications in both modes of observation to locate the precipitatesmore » and record their position within the images and calculate the distance between them. Differential scanning calorimeter analyses were conducted on selected samples. It was found that the mechanical properties of the material correlate with the minimum average distance between precipitates, which is related to the average cooling rate from solution heat treatment. - Highlights: Black-Right-Pointing-Pointer The distance between precipitates in a lead alloy is recorded. Black-Right-Pointing-Pointer The relationship between the distance and the cooling rate is established. Black-Right-Pointing-Pointer It is found that the strengthening of the alloy depends on the distance between precipitates.« less

Scanning electron microscopic and X-ray micro analysis on tooth enamel exposed to alkaline agents.

PubMed

Taubee, Fabian; Steiniger, Frank; Nietzsche, Sandor; Norén, Jörgen G

2010-01-01

The background of this study comprises two clinical cases, where patients exposed to aerosols of an alkaline and surface active cleaning agent developed loss of enamel substance on their teeth, further resulting in loss of teeth and partially destroyed soft tissues. The alkaline cleaning agent consisted of potassium hydroxide and various surfactants. The purpose of this study was to investigate possible changes in morphology and composition in human teeth enamel exposed to alkaline solutions, by means of X-ray micro analysis (XRMA), FTIR-spectroscopic analyses and scanning electron microscopy (SEM). Extracted premolars, exposed to potassium hydroxide solutions and alkaline cleaning solution,were analyzed by means of XRMA and SEM. Enamel powder, exposed to cleaning solution, was analyzed by means of FTIR. The SEM analysis revealed an increased porosity of the enamel surface and partially loss of enamel substance after exposure to alkaline solutions. The XRMA analyses revealed a decrease in carbon concentration while phosphorous and calcium showed no marked changes. The FTIR analyses showed no significant changes in peak heights or peak positions for phosphate, carbonate or hydroxide. It was concluded that human teeth enamel exposed to alkaline solutions showed loss of organic substance, marked pores in enamel surface and loss of substance in the enamel surface.

Removal of aqueous chromium and environmental CO2 by using photocatalytic TiO2 doped with tungsten.

PubMed

Trejo-Valdez, M; Hernández-Guzmán, S R; Manriquez-Ramírez, M E; Sobral, H; Martínez-Gutiérrez, H; Torres-Torres, C

2018-05-15

Removal of hexavalent chromium was accomplished by using photocatalyst materials of TiO 2 doped with tungsten oxide, environmental air as oxygen supply and white light as irradiation source. Dichromate anions in concentration ranges of 50 to 1000 μg/L were removed by means of aqueous dispersions of TiO 2 doped with tungsten. The aqueous chromium analyses were performed by Differential Pulse Voltammetry technique. Additionally, mineralization of CO 2 gas was promoted by the photocatalysis process, as was clearly shown by Raman spectroscopy and X-ray Photoelectron Spectroscopy (XPS) analyses obtained from the TiO 2 samples recovered after photocatalytic experiments. Results of sample analyses by Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HRTEM) are presented and discussed. Copyright © 2018 Elsevier B.V. All rights reserved.

Solid-phase data from cores at the proposed Dewey Burdock uranium in-situ recovery mine, near Edgemont, South Dakota

USGS Publications Warehouse

Johnson, Raymond H.; Diehl, Sharon F.; Benzel, William M.

2013-01-01

This report releases solid-phase data from cores at the proposed Dewey Burdock uranium in-situ recovery site near Edgemont, South Dakota. These cores were collected by Powertech Uranium Corporation, and material not used for their analyses were given to the U.S. Geological Survey for additional sampling and analyses. These additional analyses included total carbon and sulfur, whole rock acid digestion for major and trace elements, 234U/238U activity ratios, X-ray diffraction, thin sections, scanning electron microscopy analyses, and cathodoluminescence. This report provides the methods and data results from these analyses along with a short summary of observations.

3D correlative light and electron microscopy of cultured cells using serial blockface scanning electron microscopy

PubMed Central

Lerner, Thomas R.; Burden, Jemima J.; Nkwe, David O.; Pelchen-Matthews, Annegret; Domart, Marie-Charlotte; Durgan, Joanne; Weston, Anne; Jones, Martin L.; Peddie, Christopher J.; Carzaniga, Raffaella; Florey, Oliver; Marsh, Mark; Gutierrez, Maximiliano G.

2017-01-01

ABSTRACT The processes of life take place in multiple dimensions, but imaging these processes in even three dimensions is challenging. Here, we describe a workflow for 3D correlative light and electron microscopy (CLEM) of cell monolayers using fluorescence microscopy to identify and follow biological events, combined with serial blockface scanning electron microscopy to analyse the underlying ultrastructure. The workflow encompasses all steps from cell culture to sample processing, imaging strategy, and 3D image processing and analysis. We demonstrate successful application of the workflow to three studies, each aiming to better understand complex and dynamic biological processes, including bacterial and viral infections of cultured cells and formation of entotic cell-in-cell structures commonly observed in tumours. Our workflow revealed new insight into the replicative niche of Mycobacterium tuberculosis in primary human lymphatic endothelial cells, HIV-1 in human monocyte-derived macrophages, and the composition of the entotic vacuole. The broad application of this 3D CLEM technique will make it a useful addition to the correlative imaging toolbox for biomedical research. PMID:27445312

Structural, Morphological, Differential Scanning Calorimetric and Thermogravimetric Studies of Ball Milled Fe Doped Nanoscale La0.67Sr0.33MnO3 Manganite

NASA Astrophysics Data System (ADS)

Astik, Nidhi; Jha, Prafulla K.; Pratap, Arun

2018-03-01

The ball milling route has been used to produce the La0.67Sr0.33Mn0.85Fe0.15O3 (LSMFO) nanocrystalline sample from oxide precursors. The sample was characterized using x-ray diffraction (XRD), a scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDAX), differential scanning calorimetry (DSC) and thermogravimetric (TGA) measurements. The x-ray diffraction confirms the phase purity of sample and shows that the sample crystallizes in the rhombohedral perovskite structure with a R-3c space group. The scanning electron micrograph shows the presence of well-faceted crystallites of LSMFO. The EDAX spectrum demonstrates the molar ratio of different elements of nanocrystalline LSMFO. Furthermore, the crystallite size using the Debye-Scherrer formula and William-Hall analysis has been found as 24 nm and 29 nm, respectively. Our results support the idea that a good quality nanocrystalline LSMFO sample can be obtained using the ball milling route. We also discuss the DSC and TGA curves and analyse the results in terms of phase transition, calcination temperature and activation barrier energies.

Some strategies for quantitative scanning Auger electron microscopy

NASA Technical Reports Server (NTRS)

Browning, R.; Peacock, D. C.; Prutton, M.

1985-01-01

The general applicability of power law forms of the background in electron spectra is pointed out and exploited for background removal from under Auger peaks. This form of B(E) is found to be extremely sensitive to instrumental alignment and to fault-free construction - an observation which can be used to set up analyser configurations in an accurate way. Also, differences between N(E) and B(E) can be used to derive a spectrometer transmission function T(E). The questions of information density in an energy-analysing spatially-resolving instrument are addressed after reliable instrumental characterization has been established. Strategies involving ratio histograms, showing the population distribution of the ratio of a pair of Auger peak heights, composition scatter diagrams and windowed imaging are discussed and illustrated.

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.

Tannin bark Melalauca cajuputi powell (gelam) as green corrosion inhibitor of mild steel

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

Talib, Nur Atiqah Abu; Zakaria, Sarani; Hua, Chia Chin

Tannin was extracted from gelam bark and used to produce corrosion inhibitor for mild steel. Tannin was extracted from gelam bark using 70% aqueous acetone for 6 hour. Tannin powder was characterization using fourier transform infrared spectroscopy to analyse chemical component in tannin and Scanning electron microscope (SEM) for tannin physical structure. The tannin effect on the corrosion inhibition of mild steel has been investigated in 1Mol HCl solution for 6 hour followed ASTM. The weight loss method were applied to study the mild steel corrosion behavior in the present and absend of different concentration of tannin (250, 300, 350)ppm.more » Tannin act good inhibitor as corrosion inhibitor for mild steel in acid medium. Surface morphology of carbon steel with and without inhibitor was investigated by scanning electron microscopy.« less

LiCoPO4 cathode from a CoHPO4·xH2O nanoplate precursor for high voltage Li-ion batteries

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

Choi, Daiwon; Li, Xiaolin; Henderson, Wesley A.

2016-02-01

Highly crystalline LiCoPO4/C cathode has been synthesized without any impurities via single step solid-state reaction using CoHPO4xH2O nanoplates as a precursor obtained by simple precipitation route. The electrochemical test shows specific capacity as high as 125mAh/g at charge/discharge rate of C/10. Synthesis approach for obtaining CoHPO4xH2O nanoplate precursor and final LiCoPO4/C cathode using single step solid-state reaction have been characterized using X-ray diffraction, thermos gravimetric analyses (TGA) – differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The electrochemical test and cycling stability using different electrolytes, additive and separator have been investigated.

Synthesis and Characterization of the First Liquid Single Source Precursors for the Deposition of Ternary Chalcopyrite (CuInS2) Thin Film Materials

NASA Technical Reports Server (NTRS)

Banger, Kulbinder K.; Cowen, Jonathan; Hepp, Aloysius

2002-01-01

Molecular engineering of ternary single source precursors based on the [{PBu3}2Cu(SR')2In(SR')2] architecture have afforded the first liquid CIS ternary single source precursors (when R = Et, n-Pr), which are suitable for low temperature deposition (< 350 C). Thermogravimetric analyses (TGA) and modulated-differential scanning calorimetry (DSC) confirm their liquid phase and reduced stability. X-ray diffraction studies, energy dispersive analyzer (EDS), and scanning electron microscopy (SEM) support the formation of the single-phase chalcopyrite CuInS2 at low temperatures.

Effect of autoclaving on the surfaces of TiN -coated and conventional nickel-titanium rotary instruments.

PubMed

Spagnuolo, G; Ametrano, G; D'Antò, V; Rengo, C; Simeone, M; Riccitiello, F; Amato, M

2012-12-01

To evaluate the effects of repeated autoclave sterilization cycles on surface topography of conventional nickel-titanium ( NiTi ) and titanium nitride ( TiN )-coated rotary instruments. A total of 60 NiTi rotary instruments, 30 ProTaper (Dentsply Maillefer) and 30 TiN -coated AlphaKite (Komet/Gebr. Brasseler), were analysed. Instruments were evaluated in the as-received condition and after 1, 5 and 10 sterilization cycles. After sterilization, the samples were observed using scanning electron microscope (SEM), and surface chemical analysis was performed on each instrument with energy dispersive X-ray spectroscopy (EDS). Moreover, the samples were analysed by atomic force microscopy (AFM), and roughness average (Ra) and the root mean square value (RMS) of the scanned surface profiles were recorded. Data were analysed by means of anova followed by Tukey's test. Scanning electron microscope observations revealed the presence of pitting and deep milling marks in all instruments. EDS analysis confirmed that both types of instruments were composed mainly of nickel and titanium, whilst AlphaKite had additional nitride. After multiple autoclave sterilization cycles, SEM examinations revealed an increase in surface alterations, and EDS values indicated changes in chemical surface composition in all instruments. Ra and RMS values of ProTaper significantly increased after 5 (P = 0.006) and 10 cycles (P = 0.002) with respect to the as-received instruments, whilst AlphaKite showed significant differences compared with the controls after 10 cycles (P = 0.03). Multiple autoclave sterilization cycles modified the surface topography and chemical composition of conventional and TiN -coated NiTi rotary instruments. © 2012 International Endodontic Journal.

Studies on the annealing and antibacterial properties of the silver-embedded aluminum/silica nanospheres

PubMed Central

2014-01-01

Substantial silver-embedded aluminum/silica nanospheres with uniform diameter and morphology were successfully synthesized by sol-gel technique. After various annealing temperatures, the surface mechanisms of each sample were analyzed using scanning electron microscope, transmission electron microscope, and X-ray photoelectron spectroscopy. The chemical durability examinations and antibacterial tests of each sample were also carried out for the confirmation of its practical usage. Based on the result of the above analyses, the silver-embedded aluminum/silica nanospheres are eligible for fabricating antibacterial utensils. PMID:25136275

Photoisomerisation and light-induced morphological switching of a polyoxometalate-azobenzene hybrid.

PubMed

Markiewicz, Grzegorz; Pakulski, Dawid; Galanti, Agostino; Patroniak, Violetta; Ciesielski, Artur; Stefankiewicz, Artur R; Samorì, Paolo

2017-06-29

The functionalization of a spherical Keplerate-type polyoxometalate {Mo 72 V 30 } with a cationic azobenzene surfactant has been achieved through ionic self-assembly. The photoisomerisation reaction of this complex, which emerges in a light-triggered aggregation-disaggregation process, has been followed by 1 H NMR spectroscopy, dynamic light scattering, absorption spectroscopy and scanning electron microscopy analyses.

Electron microscopy analyses and electrical properties of the layered Bi{sub 2}WO{sub 6} phase

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

Taoufyq, A.; Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir, Maroc; Département d‘Études des Réacteurs, Laboratoire Dosimétrie Capteurs Instrumentation, CEA Cadarache

2013-07-15

The bismuth tungstate Bi{sub 2}WO{sub 6} was synthesized using a classical coprecipitation method followed by a calcination process at different temperatures. The samples were characterized by X-ray diffraction, simultaneous thermogravimetry and differential thermal analysis (TGA/DTA), scanning and transmission electron microscopy (SEM, TEM) analyses. The Rietveld analysis and electron diffraction clearly confirmed the Pca2{sub 1} non centrosymmetric space group previously proposed for this phase. The layers Bi{sub 2}O{sub 2}{sup 2+} and WO{sub 4}{sup 2−} have been directly evidenced from the HRTEM images. The electrical properties of Bi{sub 2}WO{sub 6} compacted pellets systems were determined from electrical impedance spectrometry (EIS) and directmore » current (DC) analyses, under air and argon, between 350 and 700 °C. The direct current analyses showed that the conduction observed from EIS analyses was mainly ionic in this temperature range, with a small electronic contribution. Electrical change above the transition temperature of 660 °C is observed under air and argon atmospheres. The strong conductivity increase observed under argon is interpreted in terms of formation of additional oxygen vacancies coupled with electron conduction. - Graphical abstract: High resolution transmission electron microscopy: inverse fast Fourier transform giving the layered structure of the Bi{sub 2}WO{sub 6} phase, with a representation of the cell dimensions (b and c vectors). The Bi{sub 2}O{sub 2}{sup 2+} and WO{sub 4}{sup 2−} sandwiches are visible in the IFFT image. - Highlights: • Using transmission electron microscopy, we visualize the layered structure of Bi{sub 2}WO{sub 6}. • Electrical analyses under argon gas show some increase in conductivity. • The phase transition at 660 °C is evidenced from electrical modification.« less

Keratitis-associated fungi form biofilms with reduced antifungal drug susceptibility.

PubMed

Zhang, Xiaoyan; Sun, Xuguang; Wang, Zhiqun; Zhang, Yang; Hou, Wenbo

2012-11-21

To investigate the biofilm-forming capacity of Fusarium solani, Cladosporium sphaerospermum, and Acremonium implicatum, and the activities of antifungal agents against the three keratitis-associated fungi. The architecture of biofilms was analyzed using scanning electron microscopy and confocal scanning laser microscopy (CSLM). Susceptibility against six antifungal drugs was measured using the CLSI M38-A method and XTT reduction assay. Time course analyses of CSLM revealed that biofilm formation occurred in an organized fashion through four distinct developmental phases: adhesion, germling formation, microcolony formation, and biofilm maturation. Scanning electron microscopy revealed that mature biofilms displayed a complex three-dimensional structure, consisting of coordinated network of hyphal structures glued by the extracellular matrix (ECM). The antifungal susceptibility testing demonstrated a time-dependent decrease in efficacy for all six antifungal agents as the complexity of fungal hyphal structures developed. Natamycin (NAT), amphotericin B (AMB), and NAT were the most effective against F. solani, C. sphaerospermum, and A. implicatum biofilm, respectively. Corneal isolates of F. solani, C. sphaerospermum, and A. implicatum could produce biofilms that were resistant to antifungal agents in vitro.

Microstructural and thermal study of Al-Si-Mg/melon shell ash particulate composite

NASA Astrophysics Data System (ADS)

Abdulwahab, M.; Umaru, O. B.; Bawa, M. A.; Jibo, H. A.

The microstructural study via scanning electron microscope (SEM) and thermal study via differential scanning calorimetric (DSC) study of Al-7%Si-0.3Mg/melon shell ash particulate composite has been carried out. The melon shell ash was used in the production of MMC ranging from 5% to 20% at interval of 5% addition using stir casting method. The melon shell ash was characterized using X-ray fluorescent (XRF) that reveal the presence of CaO, SiO2, Al2O3, MgO, and TiO2 as major compounds. The composite was machined and subjected to heat treatment. Microstructural analyses of the composite produced were done using scanning electron microscope (SEM). The microstructure obtained reveals a dark ceramic (reinforcer) and white metallic phase. Equally, the 5 wt% DSC result gives better thermal conductivity than other proportions (10 wt%, 15 wt%, and 20 wt%). These results showed that an improved property of Al-Si-Mg alloy was achieved using melon shell ash particles as reinforcement up to a maximum of 20 wt% for microstructural and 5% wt DSC respectively.

Novel porous CuO microrods: synthesis, characterization, and their photocatalysis property

NASA Astrophysics Data System (ADS)

Huang, Jiarui; Fu, Guijun; Shi, Chengcheng; Wang, Xinyue; Zhai, Muheng; Gu, Cuiping

2014-09-01

Porous copper oxide microrods have been synthesized via calcining copper glycinate monohydrate microrod precursor which was prepared in mild conditions without any template or additive. Several techniques, such as X-ray diffraction, field emission scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller (BET) N2 adsorption-desorption analyses, were used to characterize the structure and morphology of the products. Scanning electron microscopy (SEM) analyses show that the precursor consists of a large quantity of uniform rod-like micro/nanostructures with typical lengths in the range of 25-40 μm and diameters in the range of 0.1-0.35 μm. The microrod-like precursors transformed into porous microrod products after calcination at 450 °C in flow air for 2 h. The BET surface area of the porous CuO microrods was calculated to be 8.5 m² g-1. In addition, the obtained porous CuO microrods were used as catalysts to photodegrade rhodamine B (RhB), methyl orange, methylene blue, eosin B, and p-nitrophenol. Compared with commercial CuO powders, the as-prepared porous CuO microrods exhibit superior properties on photocatalytic decomposition of RhB due to their porous hierarchical structures.

Preparation of porous Si and TiO 2 nanofibres using a sulphur-templating method for lithium storage

DOE PAGES

McCormac, Kathleen; Byrd, Ian; Brannen, Rodney; ...

2015-02-03

We prepared highly porous Si/TiO 2 composite nanofibres using a unique sulphur-templating method combined with electrospinning. The structure, morphology, surface area, phase and composition of these nanofibres were characterized using Raman spectroscopy, scanning electron microscopy, powder X-ray diffraction, surface area analyser and thermogravimetric analyser. The specific surface area of Si/TiO 2 porous NFs is as large as 387m 2g -1, whose silicon capacity can be maintained above 1580mAhg -1 in 180 cycles.

Forensic microanalysis of Manhattan Project legacy radioactive wastes in St. Louis, MO.

PubMed

Kaltofen, Marco; Alvarez, Robert; Hixson, Lucas W

2018-06-01

Radioactive particulate matter (RPM) in St Louis, MO, area surface soils, house dusts and sediments was examined by scanning electron microscopy with energy dispersive X-ray analysis. Analyses found RPM containing 238 U and decay products (up to 46 wt%), and a distinct second form of RPM containing 230 Th and decay products (up to 15.6 wt%). The SEM-EDS analyses found similar RPM in Manhattan Project-era radioactive wastes and indoor dusts in surrounding homes. Copyright © 2018 Elsevier Ltd. All rights reserved.

Spine micromorphology of normal and hyperhydric Mammillaria gracilis Pfeiff. (Cactaceae) shoots.

PubMed

Peharec, P; Posilović, H; Balen, B; Krsnik-Rasol, M

2010-07-01

Artificial conditions of tissue culture affect growth and physiology of crassulacean acid metabolism plants which often results in formation of hyperhydric shoots. In in vitro conditions Mammillaria gracilis Pfeiff. (Cactaceae) growth switches from organized to unorganized way, producing a habituated organogenic callus which simultaneously regenerates morphologically normal as well as altered hyperhydric shoots. In this study, influence of tissue culture conditions on morphology of cactus spines of normal and hyperhydric shoots was investigated. Spines of pot-grown Mammillaria plants and of in vitro regenerated shoots were examined with stereo microscope and scanning electron microscope. The pot-grown plants had 16-17 spines per areole. In vitro grown normal shoots, even though they kept typical shoot morphology, had lower number of spines (11-12) and altered spine morphology. This difference was even more pronounced in spine number (six to seven) and morphology of the hyperhydric shoots. Scanning electron microscopy analysis revealed remarkable differences in micromorphology of spine surface between pot-grown and in vitro grown shoots. Spines of in vitro grown normal shoots showed numerous long trichomes, which were more elongated on spines of the hyperhydric shoots; the corresponding structures on spine surface of pot-grown plants were noticed only as small protrusions. Scanning electron microscopy morphometric studies showed that the spines of pot-grown plants were significantly longer compared to the spines of shoots grown in tissue culture. Moreover, transverse section shape varies from elliptical in pot-grown plants to circular in normal and hyperhydric shoots grown in vitro. Cluster and correspondence analyses performed on the scanning electron microscope obtained results suggest great variability among spines of pot-grown plants. Spines of in vitro grown normal and hyperhydric shoots showed low level of morphological variation among themselves despite the significant difference in shoot morphology.

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.

Imaging of surface spin textures on bulk crystals by scanning electron microscopy

NASA Astrophysics Data System (ADS)

Akamine, Hiroshi; Okumura, So; Farjami, Sahar; Murakami, Yasukazu; Nishida, Minoru

2016-11-01

Direct observation of magnetic microstructures is vital for advancing spintronics and other technologies. Here we report a method for imaging surface domain structures on bulk samples by scanning electron microscopy (SEM). Complex magnetic domains, referred to as the maze state in CoPt/FePt alloys, were observed at a spatial resolution of less than 100 nm by using an in-lens annular detector. The method allows for imaging almost all the domain walls in the mazy structure, whereas the visualisation of the domain walls with the classical SEM method was limited. Our method provides a simple way to analyse surface domain structures in the bulk state that can be used in combination with SEM functions such as orientation or composition analysis. Thus, the method extends applications of SEM-based magnetic imaging, and is promising for resolving various problems at the forefront of fields including physics, magnetics, materials science, engineering, and chemistry.

Cryo-Scanning Electron Microscopy of Captured Cirrus Ice Particles

NASA Astrophysics Data System (ADS)

Magee, N. B.; Boaggio, K.; Bandamede, M.; Bancroft, L.; Hurler, K.

2016-12-01

We present the latest collection of high-resolution cryo-scanning electron microscopy images and microanalysis of cirrus ice particles captured by high-altitude balloon (ICE-Ball, see abstracts by K. Boaggio and M. Bandamede). Ice particle images and sublimation-residues are derived from particles captured during approximately 15 balloon flights conducted in Pennsylvania and New Jersey over the past 12 months. Measurements include 3D digital elevation model reconstructions of ice particles, and associated statistical analyses of entire particles and particle sub-facets and surfaces. This 3D analysis reveals that morphologies of most ice particles captured deviate significantly from ideal habits, and display geometric complexity and surface roughness at multiple measureable scales, ranging from 100's nanometers to 100's of microns. The presentation suggests potential a path forward for representing scattering from a realistically complex array of ice particle shapes and surfaces.

Holographic maps of quasiparticle interference

NASA Astrophysics Data System (ADS)

Dalla Torre, Emanuele G.; He, Yang; Demler, Eugene

2016-11-01

The analysis of Fourier-transformed scanning tunnelling microscopy images with subatomic resolution is a common tool for studying the properties of quasiparticle excitations in strongly correlated materials. Although Fourier amplitudes are generally complex valued, earlier analysis primarily focused on their absolute values. Their complex phases were often deemed random, and thus irrelevant, due to the unknown positions of the impurities in the sample. Here we show how to factor out these random phases by analysing overlaps between Fourier amplitudes that differ by reciprocal lattice vectors. The resulting holographic maps provide important and previously unknown information about the electronic structures. When applied to superconducting cuprates, our method solves a long-standing puzzle of the dichotomy between equivalent wavevectors. We show that d-wave Wannier functions of the conduction band provide a natural explanation for experimental results that were interpreted as evidence for competing unconventional charge modulations. Our work opens a new pathway to identify the nature of electronic states in scanning tunnelling microscopy.

Effect of fat types on the structural and textural properties of dough and semi-sweet biscuit.

PubMed

Mamat, Hasmadi; Hill, Sandra E

2014-09-01

Fat is an important ingredient in baking products and it plays many roles in providing desirable textural properties of baking products, particularly biscuit. In this study, the effect of fat types on dough rheological properties and quality of semi-sweet biscuit (rich tea type) were investigated using various techniques. Texture profile and extensibility analysis were used to study the dough rheology, while three-point bend test and scanning electron microscopy were used to analyse the textural characteristics of final product. TPA results showed that the type of fat significantly influenced dough textural properties. Biscuit produced with higher solid fat oil showed higher breaking force but this was not significantly different when evaluated by sensory panel. Scanning electron microscopy showed that biscuit produced with palm mid-fraction had an open internal microstructure and heterogeneous air cells as compared to other samples.

Proteomic profile of Mycobacterium tuberculosis after eupomatenoid-5 induction reveals potential drug targets.

PubMed

Ghiraldi-Lopes, Luciana D; Campanerut-Sá, Paula Az; Meneguello, Jean E; Seixas, Flávio Av; Lopes-Ortiz, Mariana A; Scodro, Regiane Bl; Pires, Claudia Ta; da Silva, Rosi Z; Siqueira, Vera Ld; Nakamura, Celso V; Cardoso, Rosilene F

2017-08-01

We investigated a proteome profile, protein-protein interaction and morphological changes of Mycobacterium tuberculosis after different times of eupomatenoid-5 (EUP-5) induction to evaluate the cellular response to the drug-induced damages. The bacillus was induced to sub-minimal inhibitory concentration of EUP-5 at 12 h, 24 h and 48 h. The proteins were separated by 2D gel electrophoresis, identified by LC/MS-MS. Scanning electron microscopy and Search Tool for the Retrieval of Interacting Genes/Proteins analyses were performed. EUP-5 impacts mainly in M. tuberculosis proteins of intermediary metabolism and interactome suggests a multisite disturbance that contributes to bacilli death. Scanning electron microscopy revealed the loss of bacillary form. Some of the differentially expressed proteins have the potential to be drug targets such as citrate synthase (Rv0896), phosphoglycerate kinase (Rv1437), ketol-acid reductoisomerase (Rv3001c) and ATP synthase alpha chain (Rv1308).

Surface-functionalized cockle shell–based calcium carbonate aragonite polymorph as a drug nanocarrier

PubMed Central

Mohd Abd Ghafar, Syairah Liyana; Hussein, Mohd Zobir; Rukayadi, Yaya; Abu Bakar Zakaria, Md Zuki

2017-01-01

Calcium carbonate aragonite polymorph nanoparticles derived from cockle shells were prepared using surface functionalization method followed by purification steps. Size, morphology, and surface properties of the nanoparticles were characterized using transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, zetasizer, X-ray powder diffraction, and Fourier transform infrared spectrometry techniques. The potential of surface-functionalized calcium carbonate aragonite polymorph nanoparticle as a drug-delivery agent were assessed through in vitro drug-loading test and drug-release test. Transmission electron microscopy, field emission scanning electron microscopy, and particle size distribution analyses revealed that size, morphology, and surface characterization had been improved after surface functionalization process. Zeta potential of the nanoparticles was found to be increased, thereby demonstrating better dispersion among the nanoparticles. Purification techniques showed a further improvement in the overall distribution of nanoparticles toward more refined size ranges <100 nm, which specifically favored drug-delivery applications. The purity of the aragonite phase and their chemical analyses were verified by X-ray powder diffraction and Fourier transform infrared spectrometry studies. In vitro biological response of hFOB 1.19 osteoblast cells showed that surface functionalization could improve the cytotoxicity of cockle shell–based calcium carbonate aragonite nanocarrier. The sample was also sensitive to pH changes and demonstrated good abilities to load and sustain in vitro drug. This study thus indicates that calcium carbonate aragonite polymorph nanoparticles derived from cockle shells, a natural biomaterial, with modified surface characteristics are promising and can be applied as efficient carriers for drug delivery. PMID:28572724

Development of an environmental high-voltage electron microscope for reaction science.

PubMed

Tanaka, Nobuo; Usukura, Jiro; Kusunoki, Michiko; Saito, Yahachi; Sasaki, Katuhiro; Tanji, Takayoshi; Muto, Shunsuke; Arai, Shigeo

2013-02-01

Environmental transmission electron microscopy and ultra-high resolution electron microscopic observation using aberration correctors have recently emerged as topics of great interest. The former method is an extension of the so-called in situ electron microscopy that has been performed since the 1970s. Current research in this area has been focusing on dynamic observation with atomic resolution under gaseous atmospheres and in liquids. Since 2007, Nagoya University has been developing a new 1-MV high voltage (scanning) transmission electron microscope that can be used to observe nanomaterials under conditions that include the presence of gases, liquids and illuminating lights, and it can be also used to perform mechanical operations to nanometre-sized areas as well as electron tomography and elemental analysis by electron energy loss spectroscopy. The new instrument has been used to image and analyse various types of samples including biological ones.

Electron microscopy observations of radiation damage in irradiated and annealed tungsten

NASA Astrophysics Data System (ADS)

Grzonka, J.; Ciupiński, Ł.; Smalc-Koziorowska, J.; Ogorodnikova, O. V.; Mayer, M.; Kurzydłowski, K. J.

2014-12-01

In the present work tungsten samples were irradiated with W6+ ions with a kinetic energy of 20 MeV in order to simulate radiation damage by fast neutrons. Two samples with cumulative damage of 2.3 and 6.36 displacements per atom were produced. The scanning transmission electron microscopy investigations were carried out in order to determine structure changes resulting from the irradiation. The evolution of the damage with post implantation annealing in the temperature range 673-1100 K was also assessed. Damage profiles were studied at cross-sections. Scanning transmission electron microscopy studies of the lamellae after annealing revealed aggregation of defects and rearrangement as well as partial healing of dislocations at higher temperatures. The results confirm the higher density of radiation-induced dislocations in the near surface area of the sample (1.8 * 1014 m-2) in comparison with a deeper damage area (1.5 * 1014 m-2). Significant decrease of dislocation density was observed after annealing with a concurrent growth of dislocation loops. Transmission electron microscopy analyses show that the dislocation loops are perfect dislocations with the Burgers vectors of b = ½[ 1 1 1].

Detection of local chemical states of lithium and their spatial mapping by scanning transmission electron microscopy, electron energy-loss spectroscopy and hyperspectral image analysis.

PubMed

Muto, Shunsuke; Tatsumi, Kazuyoshi

2017-02-08

Advancements in the field of renewable energy resources have led to a growing demand for the analysis of light elements at the nanometer scale. Detection of lithium is one of the key issues to be resolved for providing guiding principles for the synthesis of cathode active materials, and degradation analysis after repeated use of those materials. We have reviewed the different techniques currently used for the characterization of light elements such as high-resolution transmission electron microscopy, scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). In the present study, we have introduced a methodology to detect lithium in solid materials, particularly for cathode active materials used in lithium-ion battery. The chemical states of lithium were isolated and analyzed from the overlapping multiple spectral profiles, using a suite of STEM, EELS and hyperspectral image analysis. The method was successfully applied in the chemical state analyses of hetero-phases near the surface and grain boundary regions of the active material particles formed by chemical reactions between the electrolyte and the active materials. © The Author 2016. 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.

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.

Duplex ultrasound surveillance after carotid artery endarterectomy.

PubMed

Al Shakarchi, Julien; Lowry, Danielle; Nath, Jay; Khawaja, Aurangzaib Z; Inston, Nicholas; Tiwari, Alok

2016-06-01

After carotid endarterectomy (CEA), patients have been regularly followed up by duplex ultrasound imaging. However, the evidence for long-term follow-up is not clear, especially if the results from an early duplex scan are normal. This study assessed and systematically reviewed the evidence base for long-term surveillance after CEA and a normal early scan. Electronic databases were searched for studies assessing duplex surveillance after CEA in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The primary outcome for this study was the incidence of restenosis after a normal early scan. The secondary outcome was the number of reinterventions after a normal early scan. The review included seven studies that reported 2317 procedures. Of those patients with a normal early scan, 2.8% (95% confidence interval, 0.7%-6%) developed a restenosis, and 0.4% (95% confidence interval, 0%-0.9%) underwent a reintervention for their restenosis during the follow-up period. This review confirms that routine postoperative duplex ultrasound surveillance after CEA is not necessary if the early duplex scan is normal. Copyright © 2016 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

High-resolution imaging of living mammalian cells bound by nanobeads-connected antibodies in a medium using scanning electron-assisted dielectric microscopy

NASA Astrophysics Data System (ADS)

Okada, Tomoko; Ogura, Toshihiko

2017-02-01

Nanometre-scale-resolution imaging technologies for liquid-phase specimens are indispensable tools in various scientific fields. In biology, observing untreated living cells in a medium is essential for analysing cellular functions. However, nanoparticles that bind living cells in a medium are hard to detect directly using traditional optical or electron microscopy. Therefore, we previously developed a novel scanning electron-assisted dielectric microscope (SE-ADM) capable of nanoscale observations. This method enables observation of intact cells in aqueous conditions. Here, we use this SE-ADM system to clearly observe antibody-binding nanobeads in liquid-phase. We also report the successful direct detection of streptavidin-conjugated nanobeads binding to untreated cells in a medium via a biotin-conjugated anti-CD44 antibody. Our system is capable of obtaining clear images of cellular organelles and beads on the cells at the same time. The direct observation of living cells with nanoparticles in a medium allowed by our system may contribute the development of carriers for drug delivery systems (DDS).

Ternary bulk heterojunction for wide spectral range organic photodetectors

NASA Astrophysics Data System (ADS)

Shin, Hojung; Kim, Jaehoon; Lee, Changhee

2017-08-01

Ternary bulk heterojunction (BHJ) system, dual electron donors and an acceptor, was studied for developing wide spectral range organic photodetectors (OPDs). With two electron donor polymers with different bandgaps and an efficient electron acceptor of [6,6]-Phenyl-C71-butyric acid methyl ester (PC70BM), different blend ratios for ternary BHJ OPD were examined to achieve high photoresponsivity over a wide spectral range. OPDs based on ternary BHJ showed improved photovoltage response compared to binary BHJ. Current-voltage (J-V) characteristics as a function of external bias and light illumination were measured to reveal the underlying charge recombination mechanism which is found to be dominantly ruled by space charge limit (SCL) effect. Additional in-depth analyses including absorbance, cross-section scanning electron microscope (SEM), incident photon-to-electron conversion efficiency (IPCE) were performed.

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

First evidence of tyre debris characterization at the nanoscale by focused ion beam

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

Milani, M.; Pucillo, F.P.; Ballerini, M.

2004-07-15

In this paper, we present a novel technique for the nanoscale characterization of the outer and inner structure of tyre debris. Tyre debris is produced by the normal wear of tyres. In previous studies, the microcharacterization and identification were performed by analytical electron microscopy. This study is a development of the characterization of surface and microstructure of tyre debris. For the first time, tyre debris was analysed by focused ion beam (FIB), a technique with 2- to 5-nm resolution that does not require any sample preparation. We studied tyre debris produced in the laboratory. We made electron and ionic imagingmore » of the surface of the material, and after a ionic cut, we studied the internal microstructure of the same sample. The tyre debris was analysed by FIB without any sample preparations unlike the case of scanning and transmission electron microscopy (SEM and TEM). Useful information was derived to improve detection and monitoring techniques of pollution by tyre degradation processes.« less

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.

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

Zhao, Donghui; Key Lab of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi, Changning, Shanghai 200050; Zhu, Yingchun, E-mail: yzhu@mail.sic.ac.cn

In this article, the polymorph selection of calcium carbonate has been successfully achieved in water-soluble carboxymethyl chitosan aqueous solution at different temperatures (25-95 {sup o}C). Vaterite is formed in carboxymethyl chitosan solution 25 {sup o}C accompanied with trace of calcite, whereas pure aragonite is obtained at 95 {sup o}C. Scanning electron microscopy and transmission electron microscopy analyses show that the products are formed from the recrystallization of nanometer crystallites. Thermodynamic and kinetic analyses reveal that the polymorph of calcium carbonate is controlled and selected by kinetics in various temperatures. As a heterogeneous nucleator and stabilizing agent, carboxymethyl chitosan changes themore » nucleation and growth of calcium carbonate from thermodynamic into kinetic control. Under kinetic limitation, the reaction rate of aragonite increases along with the elevating of temperature and surpasses the rate of vaterite above 327 K.« less

Chemical analyses of fossil bone.

PubMed

Zheng, Wenxia; Schweitzer, Mary Higby

2012-01-01

The preservation of microstructures consistent with soft tissues, cells, and other biological components in demineralized fragments of dinosaur bone tens of millions of years old was unexpected, and counter to current hypotheses of tissue, cellular, and molecular degradation. Although the morphological similarity of these tissues to extant counterparts was unmistakable, after at least 80 million years exposed to geochemical influences, morphological similarity is insufficient to support an endogenous source. To test this hypothesis, and to characterize these materials at a molecular level, we applied multiple independent chemical, molecular, and microscopic analyses to identify the presence of original components produced by the extinct organisms. Microscopic techniques included field emission scanning electron microscopy, analytical transmission electron microscopy, transmitted light microscopy (LM), and fluorescence microscopy (FM). The chemical and molecular techniques include enzyme-linked immunosorbant assay, sodium dodecyl sulfate polyacrylamide gel electrophoresis, western blot (immunoblot), and attenuated total reflectance infrared spectroscopy. In situ analyses performed directly on tissues included immunohistochemistry and time-of-flight secondary ion mass spectrometry. The details of sample preparation and methodology are described in detail herein.

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.

Coordinated in Situ Analyses of Organic Nanoglobules in the Sutter's Mill Meteorite

NASA Technical Reports Server (NTRS)

Nakamura-Messenger, K.; Messenger, S.; Keller, L. P.; Clemett, S. J.; Nguyen, A. N.; Gibson, E. K.

2013-01-01

The Sutter's Mill meteorite is a newly fallen carbonaceous chondrite that was collected and curated quickly after its fall. Preliminary petrographic and isotopic investigations suggest affinities to the CM2 carbonaceous chondrites. The primitive nature of this meteorite and its rapid recovery provide an opportunity to investigate primordial solar system organic matter in a unique new sample. Here we report in-situ analyses of organic nanoglobules in the Sutter's Mill meteorite using UV fluorescence imaging, Fourier-transform infrared spectroscopy (FTIR), scanning transmission electron microscopy (STEM), NanoSIMS, and ultrafast two-step laser mass spectrometry (ultra-L2MS).

Effect of the scanning speed on microstructural evolution and wear behaviors of laser cladding NiCrBSi composite coatings

NASA Astrophysics Data System (ADS)

Chen, J. L.; Li, J.; Song, R.; Bai, L. L.; Shao, J. Z.; Qu, C. C.

2015-09-01

Laser cladding composite coatings were fabricated on the surface of the Ti6Al4V substrate by fiber laser cladding the NiCrBSi alloy powder. The influences of scanning speed on the dilution rate and microstructure of the coatings were investigated in detail by X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). Combined with the analyses of microhardness and fracture toughness, the wear behaviors of the coatings obtained at different scanning speeds were revealed. Results indicated that the dilution rates of the coatings were similar (about 64.23%) with variations in scanning speed ranging from 5 mm/s to 15 mm/s. An abrupt decrease in dilution rate (37.06%) was observed at the scanning speed of 20 mm/s. Microstructural observation showed that the blocky TiB2 and the cellular dendrite TiC particles were uniformly dispersed in the TiNi-Ti2Ni dual-phase intermetallic compound matrix at scanning speeds of 5-15 mm/s. When the scanning speed was further increased to 20 mm/s, the stripe-shaped CrB, gray irregular-shaped Cr3C2 and black blocky TiC particles uniformly dispersed in the γ(Ni) matrix were synthesized in situ. The particles became finer with the increase in scanning speed. The average microhardness of the coating (1026.5 HV0.2) at the scanning speed of 20 mm/s was enhanced significantly compared with that of the other three coatings (about 886.4 HV0.2). The lowest average friction coefficient (about 0.371) was obtained at the scanning speed of 20 mm/s and was relatively stable with the change in sliding time. The lowest wear loss of the coating was also obtained at the scanning speed of 20 mm/s. Analyses of the worn surfaces showed that the coating prepared at the scanning speed of 20 mm/s was in good condition because of its excellent combination of resistance to micro-cutting and brittle debonding. Comparatively speaking, the coating produced at the scanning speed of 20 mm/s possessed excellent comprehensive mechanical properties.

New method for characterizing paper coating structures using argon ion beam milling and field emission scanning electron microscopy.

PubMed

Dahlström, C; Allem, R; Uesaka, T

2011-02-01

We have developed a new method for characterizing microstructures of paper coating using argon ion beam milling technique and field emission scanning electron microscopy. The combination of these two techniques produces extremely high-quality images with very few artefacts, which are particularly suited for quantitative analyses of coating structures. A new evaluation method has been developed by using marker-controlled watershed segmentation technique of the secondary electron images. The high-quality secondary electron images with well-defined pores makes it possible to use this semi-automatic segmentation method. One advantage of using secondary electron images instead of backscattered electron images is being able to avoid possible overestimation of the porosity because of the signal depth. A comparison was made between the new method and the conventional method using greyscale histogram thresholding of backscattered electron images. The results showed that the conventional method overestimated the pore area by 20% and detected around 5% more pores than the new method. As examples of the application of the new method, we have investigated the distributions of coating binders, and the relationship between local coating porosity and base sheet structures. The technique revealed, for the first time with direct evidence, the long-suspected coating non-uniformity, i.e. binder migration, and the correlation between coating porosity versus base sheet mass density, in a straightforward way. © 2010 The Authors Journal compilation © 2010 The Royal Microscopical Society.

An electron beam linear scanning mode for industrial limited-angle nano-computed tomography.

PubMed

Wang, Chengxiang; Zeng, Li; Yu, Wei; Zhang, Lingli; Guo, Yumeng; Gong, Changcheng

2018-01-01

Nano-computed tomography (nano-CT), which utilizes X-rays to research the inner structure of some small objects and has been widely utilized in biomedical research, electronic technology, geology, material sciences, etc., is a high spatial resolution and non-destructive research technique. A traditional nano-CT scanning model with a very high mechanical precision and stability of object manipulator, which is difficult to reach when the scanned object is continuously rotated, is required for high resolution imaging. To reduce the scanning time and attain a stable and high resolution imaging in industrial non-destructive testing, we study an electron beam linear scanning mode of nano-CT system that can avoid mechanical vibration and object movement caused by the continuously rotated object. Furthermore, to further save the scanning time and study how small the scanning range could be considered with acceptable spatial resolution, an alternating iterative algorithm based on ℓ 0 minimization is utilized to limited-angle nano-CT reconstruction problem with the electron beam linear scanning mode. The experimental results confirm the feasibility of the electron beam linear scanning mode of nano-CT system.

An electron beam linear scanning mode for industrial limited-angle nano-computed tomography

NASA Astrophysics Data System (ADS)

Wang, Chengxiang; Zeng, Li; Yu, Wei; Zhang, Lingli; Guo, Yumeng; Gong, Changcheng

2018-01-01

Nano-computed tomography (nano-CT), which utilizes X-rays to research the inner structure of some small objects and has been widely utilized in biomedical research, electronic technology, geology, material sciences, etc., is a high spatial resolution and non-destructive research technique. A traditional nano-CT scanning model with a very high mechanical precision and stability of object manipulator, which is difficult to reach when the scanned object is continuously rotated, is required for high resolution imaging. To reduce the scanning time and attain a stable and high resolution imaging in industrial non-destructive testing, we study an electron beam linear scanning mode of nano-CT system that can avoid mechanical vibration and object movement caused by the continuously rotated object. Furthermore, to further save the scanning time and study how small the scanning range could be considered with acceptable spatial resolution, an alternating iterative algorithm based on ℓ0 minimization is utilized to limited-angle nano-CT reconstruction problem with the electron beam linear scanning mode. The experimental results confirm the feasibility of the electron beam linear scanning mode of nano-CT system.

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.

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.

Three-dimensional ultrastructural analyses of anterior pituitary gland expose spatial relationships between endocrine cell secretory granule localization and capillary distribution.

PubMed

Yoshitomi, Munetake; Ohta, Keisuke; Kanazawa, Tomonoshin; Togo, Akinobu; Hirashima, Shingo; Uemura, Kei-Ichiro; Okayama, Satoko; Morioka, Motohiro; Nakamura, Kei-Ichiro

2016-10-31

Endocrine and endothelial cells of the anterior pituitary gland frequently make close appositions or contacts, and the secretory granules of each endocrine cell tend to accumulate at the perivascular regions, which is generally considered to facilitate secretory functions of these cells. However, three-dimensional relationships between the localization pattern of secretory granules and blood vessels are not fully understood. To define and characterize these spatial relationships, we used scanning electron microscopy (SEM) three-dimensional reconstruction method based on focused ion-beam slicing and scanning electron microscopy (FIB/SEM). Full three-dimensional cellular architectures of the anterior pituitary tissue at ultrastructural resolution revealed that about 70% of endocrine cells were in apposition to the endothelial cells, while almost 30% of endocrine cells were entirely isolated from perivascular space in the tissue. Our three-dimensional analyses also visualized the distribution pattern of secretory granules in individual endocrine cells, showing an accumulation of secretory granules in regions in close apposition to the blood vessels in many cases. However, secretory granules in cells isolated from the perivascular region tended to distribute uniformly in the cytoplasm of these cells. These data suggest that the cellular interactions between the endocrine and endothelial cells promote an uneven cytoplasmic distribution of the secretory granules.

Experimental Characterization of Electron Beam Welded SAE 5137H Thick Steel Plate

NASA Astrophysics Data System (ADS)

Kattire, Prakash; Bhawar, Valmik; Thakare, Sandeep; Patil, Sachin; Mane, Santosh; Singh, Rajkumar, Dr.

2017-09-01

Electron beam welding is known for its narrow weld zone with high depth to width ratio, less heat affected zone, less distortion and contamination. Electron beam welding is fusion welding process, where high velocity electrons impinge on material joint to be welded and kinetic energy of this electron is transformed into heat upon impact to fuse the material. In the present work electron beam welding of 60 mm thick SAE 5137H steel is studied. Mechanical and metallurgical properties of electron beam welded joint of SAE 5137H were evaluated. Mechanical properties are analysed by tensile, impact and hardness test. Metallurgical properties are investigated through optical and scanning electron microscope. The hardness traverse across weld zone shows HV 370-380, about 18% increase in the tensile strength and very low toughness of weld joint compared to parent metal. Microstructural observation shows equiaxed dendrite in the fusion zone and partial grain refinement was found in the HAZ.

Sonochemical synthesis, characterization, and effects of temperature, power ultrasound and reaction time on the morphological properties of two new nanostructured mercury(II) coordination supramolecule compounds.

PubMed

Hayati, Payam; Rezvani, Ali Reza; Morsali, Ali; Molina, Daniel Ruiz; Geravand, Samira; Suarez-Garcia, Salvio; Villaecija, Miguel Angel Moreno; García-Granda, S; Mendoza-Meroño, Rafael; Retailleau, Pascal

2017-07-01

Two new mercury(II) coordination supramolecular compounds (CSCs) (1D and 0D), [Hg(L)(I) 2 ] n (1) and [Hg 2 (L') 2 (SCN) 2 ]·2H 2 O (2) (L=2-amino-4-methylpyridine and L'=2,6-pyridinedicarboxlic acid), have been synthesized under different experimental conditions. Micrometric crystals (bulk) or nano-sized materials have been obtained depending on using the branch tube method or sonochemical irradiation. All materials have been characterized by field emission scanning electron microscope (FESEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and FT-IR spectroscopy. Single crystal X-ray analyses on compounds 1 and 2 show that Hg 2+ ions are 4-coordinated and 5-coordinated, respectively. Topological analysis shows that the compound 1 and 2 have 2C1, sql net. The thermal stability of compounds 1 and 2 in bulk and nano-size has been studied by thermal gravimetric (TG), differential thermal analyses (DTA) for 1 and differential scanning calorimetry (DSC) for 2, respectively. Also, by changing counter ions were obtained various structures 1 and 2 (1D and 0D, respectively). The role of different parameters like power of ultrasound irradiation, reaction time and temperature on the growth and morphology of the nano-structures are studied. Results suggest that increasing power ultrasound irradiation and temperature together with reducing reaction time and concentration of initial reagents leads to a decrease in particle size. Copyright © 2017 Elsevier B.V. All rights reserved.

Highly spatially resolved structural and optical investigation of Bi nanoparticles in Y-Er disilicate thin films

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

Scarangella, A.; Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, 95123 Catania; Amiard, G.

2016-08-08

Er-containing silicon compatible materials have been widely used as infrared emitters for microphotonics application. In this field, the additional introduction of a proper sensitizer permits to increase the Er excitation cross sections, thus increasing its optical efficiency. This work aims to investigate the influence of a post-transition metal, bismuth, on the optical properties of erbium-yttrium disilicate thin films synthesized by magnetron co-sputtering. After thermal treatments at 1000 °C in O{sub 2} or N{sub 2} environment, the presence of small precipitates, about 6 nm in diameter, was evidenced by transmission electron microscopy analyses. The spatially resolved chemical nature of the nanoparticles was discernedmore » in the Si and O rich environments by means of scanning transmission electron microscopy–energy dispersive X-ray and scanning transmission electron microscopy–electron energy loss spectroscopy analyses performed with nanometric resolution. In particular, metallic Bi nanoparticles were stabilized in the N{sub 2} environment, being strongly detrimental for the Er emission. A different scenario was instead observed in O{sub 2}, where the formation of Bi silicate nanoparticles was demonstrated with the support of photoluminescence excitation spectroscopy. In particular, a broad band peaked at 255 nm, correlated to the excitation band of Bi silicate nanoparticles, was identified in Er excitation spectrum. Thus Bi silicate clusters act as sensitizer for Er ions, permitting to improve Er emission up to 250 times with respect to the resonant condition. Moreover, the Er decay time increases in the presence of the Bi silicate nanoparticles that act as cages for Er ions. These last results permit to further increase Er optical efficiency in the infrared range, suggesting (Bi + Er)-Y disilicate as a good candidate for applications in microphotonics.« less

Subgrain boundary analyses in deformed orthopyroxene by TEM/STEM with EBSD-FIB sample preparation technique

NASA Astrophysics Data System (ADS)

Kogure, Toshihiro; Raimbourg, Hugues; Kumamoto, Akihito; Fujii, Eiko; Ikuhara, Yuichi

2014-12-01

High-resolution structure analyses using electron beam techniques have been performed for the investigation of subgrain boundaries (SGBs) in deformed orthopyroxene (Opx) in mylonite from Hidaka Metamorphic Belt, Hokkaido, Japan, to understand ductile deformation mechanism of silicate minerals in shear zones. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) analysis of Opx porphyroclasts in the mylonitic rock indicated that the crystal orientation inside the Opx crystals gradually changes by rotation about the b-axis by SGBs and crystal folding. In order to observe the SGBs along the b-axis by transmission electron microscopy (TEM) or scanning TEM (STEM), the following sample preparation protocol was adopted. First, petrographic thin sections were slightly etched with hydrofluoric acid to identify SGBs in SEM. The Opx crystals whose b-axes were oriented close to the normal of the surface were identified by EBSD, and the areas containing SGBs were picked and thinned for (S) TEM analysis with a focused ion beam instrument with micro-sampling system. High-resolution TEM imaging of the SGBs in Opx revealed various boundary structures from a periodic array of dissociated (100) [001] edge dislocations to partially or completely incoherent crystals, depending on the misorientation angle. Atomic-resolution STEM imaging clearly confirmed the formation of clinopyroxene (Cpx) structure between the dissociated partial dislocations. Moreover, X-ray microanalysis in STEM revealed that the Cpx contains a considerable amount of calcium replacing iron. Such chemical inhomogeneity may limit glide motion of the dislocation and eventually the plastic deformation of the Opx porphyroclasts at a low temperature. Chemical profiles across the high-angle incoherent SGB also showed an enrichment of the latter in calcium at the boundary, suggesting that SGBs are an efficient diffusion pathway of calcium out of host Opx grain during cooling.

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.

Surface modification of boron nitride nanosheets by polyelectrolytes via atom transfer radical polymerization

NASA Astrophysics Data System (ADS)

Wu, Yuanpeng; Guo, Meiling; Liu, Guanfei; Xue, Shishan; Xia, Yuanmeng; Liu, Dan; Lei, Weiwei

2018-04-01

In this study, the surface modification of boron nitride nanosheets (BNNSs) with poly 2-acrylamido-2-methyl- propanesulfonate (PAMPS) brushes is achieved through electron transfer atom transfer radical polymerization (ARGET ATRP). BNNSs surface was first modified with α-bromoisobutyryl bromide (BIBB) via hydroxyl groups, then PAMPS brushes were grown on the surface through ARGET ATRP. Polyelectrolyte brushes modified BNNSs were further characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyses (TGA), x-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The concentraction of water-dispersion of BNNSs have been enhanced significantly by PAMPS and the high water-dispersible functional BNNSs/PAMPS composites are expected to have potential applications in biomedical and thermal management in electronics.

A facile thermal decomposition route to synthesise CoFe2O4 nanostructures

NASA Astrophysics Data System (ADS)

Kalpanadevi, K.; Sinduja, C. R.; Manimekalai, R.

2014-01-01

The synthesis of CoFe2O4 nanoparticles has been achieved by a simple thermal decomposition method from an inorganic precursor, cobalt ferrous cinnamate hydrazinate (CoFe2(cin)3(N2H4)3) which was obtained by a novel precipitation method from the corresponding metal salts, cinnamic acid and hydrazine hydrate. The precursor was characterized by hydrazine and metal analyses, infrared spectral analysis and thermo gravimetric analysis. Under appropriate annealing, CoFe2(cin)3(N2H4)3 yielded CoFe2O4 nanoparticles, which were characterized for their size and structure using X-Ray diffraction (XRD), high resolution transmission electron microscopic (HRTEM), selected area electron diffraction (SAED) and scanning electron microscopic (SEM) techniques.

Electron Spectroscopy for Chemical Analysis (ESCA) study of atmospheric particles

NASA Technical Reports Server (NTRS)

Dillard, J. G.; Seals, R. D.; Wightman, J. P.

1979-01-01

The results of analyses by ESCA (Electron Spectroscopy for Chemical Analysis) on several Nuclepore filters which were exposed during air pollution studies are presented along with correlative measurements by Neutron Activation Analysis and Scanning Electron Microscopy. Samples were exposed during air pollution studies at Norfolk, Virginia and the NASA Kennedy Space Center (KSC). It was demonstrated that with the ESCA technique it was possible to identify the chemical (bonding) state of elements contained in the atmospheric particulate matter collected on Nuclepore filters. Sulfur, nitrogen, mercury, chlorine, alkali, and alkaline earth metal species were identified in the Norfolk samples. ESCA binding energy data for aluminum indicated that three chemically different types of aluminum are present in the launch and background samples from NASA-KSC.

KOH concentration effect on the cycle life of nickel-hydrogen cells. Part 4: Results of failure analyses

NASA Technical Reports Server (NTRS)

Lim, H. S.; Verzwyvelt, S. A.

1989-01-01

KOH concentration effects on cycle life of a Ni/H2 cell have been studied by carrying out a cycle life test of ten Ni/H2 boiler plate cells which contain electrolytes of various KOH concentrations. Failure analyses of these cells were carried out after completion of the life test which accumulated up to 40,000 cycles at an 80 percent depth of discharge over a period of 3.7 years. These failure analyses included studies on changes of electrical characteristics of test cells and component analyses after disassembly of the cell. The component analyses included visual inspections, dimensional changes, capacity measurements of nickel electrodes, scanning electron microscopy, BET surface area measurements, and chemical analyses. Results have indicated that failure mode and change in the nickel electrode varied as the concentration was varied, especially, when the concentration was changed from 31 percent or higher to 26 percent or lower.

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

Scanning transmission ion micro-tomography (STIM-T) of biological specimens.

PubMed

Schwertner, Micheal; Sakellariou, Arthur; Reinert, Tilo; Butz, Tilman

2006-05-01

Computed tomography (CT) was applied to sets of Scanning Transmission Ion Microscopy (STIM) projections recorded at the LIPSION ion beam laboratory (Leipzig) in order to visualize the 3D-mass distribution in several specimens. Examples for a test structure (copper grid) and for biological specimens (cartilage cells, cygospore) are shown. Scanning Transmission Micro-Tomography (STIM-T) at a resolution of 260 nm was demonstrated for the first time. Sub-micron features of the Cu-grid specimen were verified by scanning electron microscopy. The ion energy loss measured during a STIM-T experiment is related to the mass density of the specimen. Typically, biological specimens can be analysed without staining. Only shock freezing and freeze-drying is required to preserve the ultra-structure of the specimen. The radiation damage to the specimen during the experiment can be neglected. This is an advantage compared to other techniques like X-ray micro-tomography. At present, the spatial resolution is limited by beam position fluctuations and specimen vibrations.

Analysis of FIB-induced damage by electron channelling contrast imaging in the SEM.

PubMed

Gutierrez-Urrutia, Ivan

2017-01-01

We have investigated the Ga + ion-damage effect induced by focused ion beam (FIB) milling in a [001] single crystal of a 316 L stainless steel by the electron channelling contrast imaging (ECCI) technique. The influence of FIB milling on the characteristic electron channelling contrast of surface dislocations was analysed. The ECCI approach provides sound estimation of the damage depth produced by FIB milling. For comparison purposes, we have also studied the same milled surface by a conventional electron backscatter diffraction (EBSD) approach. We observe that the ECCI approach provides further insight into the Ga + ion-damage phenomenon than the EBSD technique by direct imaging of FIB artefacts in the scanning electron microscope. We envisage that the ECCI technique may be a convenient tool to optimize the FIB milling settings in applications where the surface crystal defect content is relevant. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

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.

External cervical resorption: an analysis using cone beam and microfocus computed tomography and scanning electron microscopy.

PubMed

Gunst, V; Mavridou, A; Huybrechts, B; Van Gorp, G; Bergmans, L; Lambrechts, P

2013-09-01

To provide a three-dimensional representation of external cervical resorption (ECR) with microscopy, stereo microscopy, cone beam computed tomography (CT), microfocus CT and scanning electron microscopy (SEM). External cervical resorption is an aggressive form of root resorption, leading to a loss of dental hard tissues. This is due to clastic action, activated by a damage of the covering cementum and stimulated probably by infection. Clinically, it is a challenging situation as it is characterized by a late symptomatology. This is due to the pericanalar protection from a resorption-resistant sheet, composed of pre-dentine and surrounding dentine. The clastic activity is often associated with an attempt to repair, seen by the formation of osteoid tissue. Cone beam CT is extremely useful in the diagnoses and treatment planning of ECR. SEM analyses provide a better insight into the activity of osteoclasts. The root canal is surrounded by a layer of dentine that is resistant to resorption. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Mineralogy of mine waste at the Vermont Asbestos Group mine, Belvidere Mountain, Vermont

USGS Publications Warehouse

Levitan, D.M.; Hammarstrom, J.M.; Gunter, M.E.; Seal, R.R.; Chou, I.-Ming; Piatak, N.M.

2009-01-01

Samples from the surfaces of waste piles at the Vermont Asbestos Group mine in northern Vermont were studied to determine their mineralogy, particularly the presence and morphology of amphiboles. Analyses included powder X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and Raman spectroscopy. Minerals identified by XRD were serpentine-group minerals, magnetite, chlorite, quartz, olivine, pyroxene, and brucite; locally, mica and carbonates were also present. Raman spectroscopy distinguished antigorite and chrysotile, which could not be differentiated using XRD. Long-count, short-range XRD scans of the (110) amphibole peak showed trace amounts of amphibole in most samples. Examination of amphiboles in tailings by optical microscopy, SEM, and EPMA revealed non-fibrous amphiboles compositionally classified as edenite, magnesiohornblende, magnesiokatophorite, and pargasite. No fibrous amphibole was found in the tailings, although fibrous tremolite was identified in a sample of host rock. Knowledge of the mineralogy at the site may lead to better understanding of potential implications for human health and aid in designing a remediation plan.

Luminescent properties under X-ray excitation of Ba(1-x)PbxWO4 disordered solid solution

NASA Astrophysics Data System (ADS)

Bakiz, B.; Hallaoui, A.; Taoufyq, A.; Benlhachemi, A.; Guinneton, F.; Villain, S.; Ezahri, M.; Valmalette, J.-C.; Arab, M.; Gavarri, J.-R.

2018-02-01

A series of polycrystalline barium-lead tungstate Ba1-xPbxWO4 with 0 ≤ x ≤ 1 was synthesized using a classical solid-state method with thermal treatment at 1000 °C. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Raman (FT-Raman) spectroscopy. X-ray diffraction profile analyses were performed using Rietveld method. These materials crystallized in the scheelite tetragonal structure and behaved as quasi ideal solid solution. Raman spectroscopy confirmed the formation of the solid solution. Structural distortions were evidenced in X-ray diffraction profiles and in vibration Raman spectra. The scanning electron microscopy experiments showed large and rounded irregular grains. Luminescence experiments were performed under X-ray excitation. The luminescence emission profiles have been interpreted in terms of four Gaussian components, with a major contribution of blue emission. The integrated intensity of luminescence reached a maximum value in the composition range x = 0.3-0.6, in relation with distortions of crystal lattice.

A novel fibrinogen variant--Liberec: dysfibrinogenaemia associated with gamma Tyr262Cys substitution.

PubMed

Kotlín, Roman; Sobotková, Alzbeta; Suttnar, Jirí; Salaj, Peter; Walterová, Lenka; Riedel, Tomás; Reicheltová, Zuzana; Dyr, Jan Evangelista

2008-08-01

A 22-yr-old woman had abnormal preoperative coagulation test results and congenital dysfibrinogenaemia was suspected. The patient from Liberec (Czech Republic) had a low fibrinogen plasma level as determined by Clauss method, normal fibrinogen level as determined by immunoturbidimetrical method, and prolonged thrombin time. To identify the genetic mutation responsible for this dysfibrinogen, genomic DNA extracted from the blood was analysed. Fibrin polymerisation measurement, kinetics of fibrinopeptide release, fibrinogen clottability measurement and scanning electron microscopy were performed. DNA sequencing showed the heterozygous fibrinogen gamma Y262C mutation. Kinetics of fibrinopeptide release was normal, however fibrin polymerisation was impaired. Fibrinogen clottability measurement showed that only about 45% molecules of fibrinogen are involved in the clot formation. Scanning electron microscopy revealed thicker fibres, which were significantly different from the normal control. A case of dysfibrinogenaemia, found by routine coagulation testing, was genetically identified as a novel fibrinogen variant (gamma Y262C) that has been named Liberec.

The low-temperature method for study of coniferous tissues in the environmental scanning electron microscope.

PubMed

Neděla, Vilém; Tihlaříková, Eva; Hřib, Jiří

2015-01-01

The use of non-standard low-temperature conditions in environmental scanning electron microscopy might be promising for the observation of coniferous tissues in their native state. This study is aimed to analyse and evaluate the method based on the principle of low-temperature sample stabilization. We demonstrate that the upper mucous layer is sublimed and a microstructure of the sample surface can be observed with higher resolution at lower gas pressure conditions, thanks to a low-temperature method. An influence of the low-temperature method on sample stability was also studied. The results indicate that high-moisture conditions are not suitable for this method and often cause the collapse of samples. The potential improvement of stability to beam damage has been demonstrated by long-time observation at different operation parameters. We finally show high applicability of the low-temperature method on different types of conifers and Oxalis acetosella. © 2014 Wiley Periodicals, Inc.

Synthesis of porous SnO2 nanocubes via selective leaching and enhanced gas-sensing properties

NASA Astrophysics Data System (ADS)

Li, Yining; Wei, Qi; Song, Peng; Wang, Qi

2016-01-01

Porous micro-/nanostructures are of great interest in many current and emerging areas of technology. In this paper, porous SnO2 nanocubes have been successfully fabricated via a selective leaching strategy using CoSn(OH)6 as precursor. The structure and morphology of as-prepared samples were investigated by several techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric and differential scanning calorimeter analysis (TG⿿DSC), transmission electron microscopy (TEM) and N2 adsorption⿿desorption analyses. On the basis of those characterizations, the mechanism for the formation of porous SnO2 nanocubes has been proposed. Owing to the well-defined and uniform porous structures, porous SnO2 nanocubes possessing more adsorbent amount of analytic gas and accelerate the transmission speed so as to enhance the gas-sensing properties. Gas sensing investigation showed that the sensor based on porous SnO2 nanocubes exhibited high response, short response⿿recovery times and good selectivity to ethanol gas.

In search of the elusive IrB 2: Can mechanochemistry help?

DOE PAGES

Xie, Zhilin; Blair, Richard G.; Orlovskaya, Nina; ...

2015-10-20

We produced hexagonal ReB 2-type IrB 2 diboride and orthorhombic IrB monoboride phases, that were previously unknown and saw them produced by mechanochemical syntheses. High energy ball milling of elemental Ir and B powder for 30 h, followed by annealing of the powder at 1050 °C for 48 h, resulted in the formation of the desired phases. Both traditional laboratory and high resolution synchrotron X-ray diffraction (XRD) analyses were used for phase identification of the synthesized powder. Additionally, scanning electron microscopy and transmission electron microscopy were employed, along with XRD, to further characterize the microstructure of the phases produced.

In search of the elusive IrB 2: Can mechanochemistry help?

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

Xie, Zhilin; Blair, Richard G.; Orlovskaya, Nina

We produced hexagonal ReB 2-type IrB 2 diboride and orthorhombic IrB monoboride phases, that were previously unknown and saw them produced by mechanochemical syntheses. High energy ball milling of elemental Ir and B powder for 30 h, followed by annealing of the powder at 1050 °C for 48 h, resulted in the formation of the desired phases. Both traditional laboratory and high resolution synchrotron X-ray diffraction (XRD) analyses were used for phase identification of the synthesized powder. Additionally, scanning electron microscopy and transmission electron microscopy were employed, along with XRD, to further characterize the microstructure of the phases produced.

Development of 1500mm Wide Wrought Magnesium Alloys by Twin Roll Casting Technique in Turkey

NASA Astrophysics Data System (ADS)

Duygulu, Ozgur; Ucuncuoglu, Selda; Oktay, Gizem; Temur, Deniz Sultan; Yucel, Onuralp; Kaya, Ali Arslan

Magnesium alloy AZ31, AZ61, AZ91, AM50 and AM60 sheets were produced by twin roll casting first time in Turkey. Sheets of 4.5-6.5mm thick and 1500mm width were successfully achieved. Microstructure of the sheet was analyzed by optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). Semi-quantitative analyses were performed by SEM-EDS. In addition, X-ray studies were performed for both characterization and texture purposes. Mechanical properties were investigated by tensile tests and also hardness measurements. Homogenization and annealing heat treatments were performed on the produced sheets.

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.

One-Pot Silver Nanoring Synthesis

NASA Astrophysics Data System (ADS)

Drogat, Nicolas; Granet, Robert; Sol, Vincent; Krausz, Pierre

2010-03-01

Silver colloidal nanorings have been synthesized by reducing silver ions with NaBH4 in trisodium citrate buffers. pH increase, by addition of NaOH, was used to speed up reduction reaction. The UV-vis absorption spectra of resulting silver nanorings showed two peaks accounting for transverse and longitudinal surface plasmon resonance, at ≈400 nm, and between 600 and 700 nm, respectively. The shapes of these silver nanoparticles (nanorings) depended on AgNO3/NaBH4 ratio, pH and reaction temperature. Particles were analysed by transmission electron microscopy, scanning electron microscopy and X-ray diffraction. A reaction pathway is proposed to explain silver nanoring formation.

One-pot silver nanoring synthesis.

PubMed

Drogat, Nicolas; Granet, Robert; Sol, Vincent; Krausz, Pierre

2009-12-16

Silver colloidal nanorings have been synthesized by reducing silver ions with NaBH4 in trisodium citrate buffers. pH increase, by addition of NaOH, was used to speed up reduction reaction. The UV-vis absorption spectra of resulting silver nanorings showed two peaks accounting for transverse and longitudinal surface plasmon resonance, at ≈400 nm, and between 600 and 700 nm, respectively. The shapes of these silver nanoparticles (nanorings) depended on AgNO3/NaBH4 ratio, pH and reaction temperature. Particles were analysed by transmission electron microscopy, scanning electron microscopy and X-ray diffraction. A reaction pathway is proposed to explain silver nanoring formation.

One-Pot Silver Nanoring Synthesis

PubMed Central

2010-01-01

Silver colloidal nanorings have been synthesized by reducing silver ions with NaBH4 in trisodium citrate buffers. pH increase, by addition of NaOH, was used to speed up reduction reaction. The UV–vis absorption spectra of resulting silver nanorings showed two peaks accounting for transverse and longitudinal surface plasmon resonance, at ≈400 nm, and between 600 and 700 nm, respectively. The shapes of these silver nanoparticles (nanorings) depended on AgNO3/NaBH4 ratio, pH and reaction temperature. Particles were analysed by transmission electron microscopy, scanning electron microscopy and X-ray diffraction. A reaction pathway is proposed to explain silver nanoring formation. PMID:20672109

Reaction layer formation at the graphite/copper-chromium alloy interface

NASA Technical Reports Server (NTRS)

Devincent, Sandra M.; Michal, Gary M.

1992-01-01

Sessile drop tests were used to obtain information about copper chromium alloys that suitably wet graphite. Characterization of graphite/copper-chromium alloy interfaces subjected to elevated temperatures were conducted using scanning electron micrography, energy dispersive spectroscopy, auger electron spectroscopy, and x ray diffraction analyses. These analyses indicate that during sessile drop tests conducted at 1130 C for one hour, copper alloys containing greater than 0.98 percent chromium form continuous reaction layers of approximately 10 micron thickness. The reaction layers adhere to the graphite surface. The copper wets the reaction layer to form a contact angle of 60 degrees or less. X ray diffraction results indicate that the reaction layer is chromium carbide. The kinetics of reaction layer formation were modelled in terms of bulk diffusion mechanisms. Reaction layer thickness is controlled initially by the diffusion of Cr out of Cu alloy and later by the diffusion of C through chromium carbide.

An in vitro study of the microstructure, composition and nanoindentation mechanical properties of remineralizing human dental enamel

NASA Astrophysics Data System (ADS)

Arsecularatne, J. A.; Hoffman, M.

2014-08-01

This paper describes the results of an in vitro investigation on the interrelations among microstructure, composition and mechanical properties of remineralizing human dental enamel. Polished enamel samples have been demineralized for 10 min in an acetic acid solution (at pH 3) followed by remineralization in human saliva for 30 and 120 min. Microstructure variations of sound, demineralized and remineralized enamel samples have been analysed using focused ion beam, scanning electron microscopy and transmission electron microscopy, while their compositions have been analysed using energy dispersive x-ray. Variations in the mechanical properties of enamel samples have been assessed using nanoindentation. The results reveal that, under the selected conditions, only partial remineralization of the softened enamel surface layer occurs where some pores remain unrepaired. As a result, while the nanoindentation elastic modulus shows an improvement following remineralization, hardness does not.

Reaction layer formation at the graphite/copper-chromium alloy interface

NASA Technical Reports Server (NTRS)

Devincent, Sandra M.; Michal, Gary M.

1993-01-01

Sessile drop tests were used to obtain information about copper chromium alloys that suitably wet graphite. Characterization of graphite/copper-chromium alloy interfaces subjected to elevated temperatures were conducted using scanning electron micrography, energy dispersive spectroscopy, Auger electron spectroscopy, and X-ray diffraction analyses. These analyses indicate that during sessile drop tests conducted at 1130 C for one hour, copper alloys containing greater than 0.98 percent chromium form continuous reaction layers of approximately 10 micron thickness. The reaction layers adhere to the graphite surface. The copper wets the reaction layer to form a contact angle of 60 degrees or less. X-ray diffraction results indicate that the reaction layer is chromium carbide. The kinetics of reaction layer formation were modelled in terms of bulk diffusion mechanisms. Reaction layer thickness is controlled initially by the diffusion of Cr out of Cu alloy and later by the diffusion of C through chromium carbide.

Laser-Induced Breakdown Spectroscopy (LIBS) for Monitoring the Formation of Hydroxyapatite Porous Layers

PubMed Central

Sola, Daniel; Paulés, Daniel; Grima, Lorena

2017-01-01

Laser-induced breakdown spectroscopy (LIBS) is applied to characterize the formation of porous hydroxyapatite layers on the surface of 0.8CaSiO3-0.2Ca3(PO4)2 biocompatible eutectic glass immersed in simulated body fluid (SBF). Compositional and structural characterization analyses were also conducted by field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), and micro-Raman spectroscopy. PMID:29211006

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.

Enhanced Electro-Kinetics of C-C Bond-Splitting during Ethanol Oxidation Reaction using Pt/Rh/Sn Catalyst with a Partially Oxidized Pt and Rh Core and a SnO2 Shell

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

Yang, G.; Su, D.; Frenkel, A. I.

Direct ethanol fuel cell (DEFC) is a promising technology for generating electricity via the electro-oxidation of liquid ethanol. Its implementation requires the development of anode catalysts capable of producing CO 2 and yielding 12-electron transfer through breaking C-C bond of ethanol. Here we presented comprehensive studies of electro-kinetics of the CO 2 generation on Pt/Rh/Sn ternary catalysts. Our studies showed that, for the first time, the tri–phase PtRhOx- SnO 2 catalysts with a partially oxidized Pt and Rh core and a SnO 2 shell, validated by X-ray absorption analyses and scanning transmission electron microscope-electron energy loss spectroscopy line scan, coincidedmore » with a 2.5-fold increase in the CO 2 generation rate towards ethanol oxidation reaction, compared with the bi-phase PtRh-SnO 2 catalysts with a metallic PtRh alloy core and commercial Pt. These studies provided insight on the design of a new genre of electro-catalysts with a partially oxidized noble metal.« less

Ultrastructure of selected struvite-containing urinary calculi from cats.

PubMed

Neumann, R D; Ruby, A L; Ling, G V; Schiffman, P S; Johnson, D L

1996-01-01

To elucidate the ultrastructural details of struvite-containing urinary calculi from cats. Specimens studied were inclusive of the range of textures visible during preliminary analysis by use of a stereoscopic dissecting microscope. Textural types, which were used to infer crystal growth conditions, were differentiated with regard to crystal habit, crystal size, growth orientation, and primary porosity. Thirty specimens were selected from a collection of approximately 1,600 feline urinary calculi: 20 of these were composed entirely of struvite, and 10 consisted of struvite and calcium phosphate (apatite). Qualitative and quantitative analyses of specimens included use of plain and polarized light microscopy, x-ray diffractometry, scanning electron microscopy with backscattered electron imagery, x-ray fluorescence scans, and electron probe microanalysis. Four textural types were recognized among struvite calculi, whereas 2 textural types of struvite-apatite calculi were described. The presence of minute, well interconnected primary pores in struvite-containing urinary calculi from cats is an important feature, which may promote possible interaction of calculi with changes in urine composition. Primary porosity, which can facilitate interaction between the calculus and changing urine composition, may explain the efficacy of dietary or medicinal manipulations to promote the dissolution of struvite-containing uroliths from this species.

Enhanced Electro-Kinetics of C-C Bond-Splitting during Ethanol Oxidation Reaction using Pt/Rh/Sn Catalyst with a Partially Oxidized Pt and Rh Core and a SnO2 Shell

DOE PAGES

Yang, G.; Su, D.; Frenkel, A. I.; ...

2016-09-04

Direct ethanol fuel cell (DEFC) is a promising technology for generating electricity via the electro-oxidation of liquid ethanol. Its implementation requires the development of anode catalysts capable of producing CO 2 and yielding 12-electron transfer through breaking C-C bond of ethanol. Here we presented comprehensive studies of electro-kinetics of the CO 2 generation on Pt/Rh/Sn ternary catalysts. Our studies showed that, for the first time, the tri–phase PtRhOx- SnO 2 catalysts with a partially oxidized Pt and Rh core and a SnO 2 shell, validated by X-ray absorption analyses and scanning transmission electron microscope-electron energy loss spectroscopy line scan, coincidedmore » with a 2.5-fold increase in the CO 2 generation rate towards ethanol oxidation reaction, compared with the bi-phase PtRh-SnO 2 catalysts with a metallic PtRh alloy core and commercial Pt. These studies provided insight on the design of a new genre of electro-catalysts with a partially oxidized noble metal.« less

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.

A multifunctional cotton fabric using TiO2 and PCMs: introducing thermal comfort and self-cleaning properties

NASA Astrophysics Data System (ADS)

Scacchetti, F. A. P.; Pinto, E.; Soares, G.

2017-10-01

The development of materials with multiple functionalities is a market imperative that places new challenges on textile processing. The purpose of this study was to establish the conditions to obtain a cotton material that is comfortable, with self-cleaning and antimicrobial properties. For this purpose, microcapsules of phase change materials (mPCM) and titanium dioxide nanoparticles (TiO2 NP) were applied. The resulting fabrics were characterized with resource to infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), contact angle and scanning electron microscopy (SEM). The self-cleaning properties of treated fabrics were also analysed based on the photocatalytic ability of coated fabrics. Therefore, the decomposition of methyl orange (MO) and the degradation of red wine and curry spots under the irradiation of a solar simulator were analysed. Thus, the incorporation of TiO2 particles into the cotton fabric promoted self-cleaning and antibacterial characteristics, but the presence of PCM combined with TiO2 increases the bioactivity of materials.

Electron microscopic evaluation of a gold glaucoma micro shunt after explantation.

PubMed

Berk, Thomas A; Tam, Diamond Y; Werner, Liliana; Mamalis, Nick; Ahmed, Iqbal Ike K

2015-03-01

We present a case of an explanted gold glaucoma micro shunt (GMS Plus) and the subsequent light and electron microscopic analyses. The shunt was implanted in a patient with medically refractive glaucoma. The intraocular pressure (IOP) was stable at 12 mm Hg 6 months postoperatively but spiked to 26 mm Hg 6 months later; membranous growth was visible on the implant gonioscopically. A second gold micro shunt was placed 2 years after the first. The IOP was 7 mm Hg 1 week postoperatively but increased to 23 mm Hg 3 weeks later; similar membranous growth was visible on this implant. One of the shunts was explanted, and light and scanning electron microscopic analyses revealed encapsulation around the shunt exterior and connective tissue invasion of the microstructure. This represents the first electron microscopic analysis of an explanted gold glaucoma micro shunt and the first unequivocal images of the fibrotic pseudo-capsule traversing its microchannels and fenestrations. Dr. Ahmed is a consultant to and has received research grants from Solx, Inc. No other author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

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

Iba Techniques to Study Renaissance Pottery Techniques

NASA Astrophysics Data System (ADS)

Bouquillon, A.; Castaing, J.; Salomon, J.; Zucchiatti, A.; Lucarelli, F.; Mando, P. A.; Prati, P.; Lanterna, G.; Vaccari, M. G.

2001-09-01

The application of Ion Beam Analysis, associated to Scanning Electron Microscopy is examined in connection with an extensive program on structural and chemical analyses of glazed terracotta's from the Italian Renaissance, launched by a French-Italian collaboration in the framework of the European COST-G1 scientific action. The objectives of the collaboration are reviewed. The compatibility of data from different specimen and various laboratories are discussed. Examples of the PIXE and statistical analyses on some artefacts of the "Robbiesche" type, supplied by the Louvre Museum of Paris and the Opificio delle Pietre Dure of Florence, are given to illustrate the performances of IBA in this particular field.

Scanning electron microscopy analysis of hair index on Karachi's population for social and professional appearance enhancement.

PubMed

Ali, N; Zohra, R R; Qader, S A U; Mumtaz, M

2015-06-01

Hair texture, appearance and pigment play an important role in social and professional communication and maintaining an overall appearance. This study was especially designed for morphological assessment of hair damage caused to Karachi's population due to natural factors and cosmetic treatments using scanning electron microscopy (SEM) technique. Hair samples under the study of synthetic factor's effect were given several cosmetic treatments (hot straightened, bleached, synthetic dyed and henna dyed) whereas samples under natural factor's effect (variation in gender, age and pigmentation) were left untreated. Morphological assessment was performed using SEM technique. Results obtained were statistically analysed using minitab 16 and spss 18 softwares. Scanning electron microscopy images revealed less number of cuticular scales in males than females of same age although size of cuticular scales was found to be larger in males than in females. Mean hair index of white hair was greater than black hair of the same head as it is comparatively newly originated. Tukey's method revealed that among cosmetic treatments, bleaching and synthetic henna caused most of the damage to the hair. Statistical evaluation of results obtained from SEM analysis revealed that human scalp hair index show morphological variation with respect to age, gender, hair pigmentation, chemical and physical treatments. Individuals opting for cosmetic treatments could clearly visualize the extent of hair damage these may cause in long run. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

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.

Impact of the introduction of emergency ultrasound to one large UK emergency department: the REBUS study.

PubMed

Kwok, T'ng Choong; Johnson, Sue; Reed, Matthew James

2013-02-01

Firstly, to detail the experiences of one UK training region in establishing an emergency ultrasound (EU) training programme and secondly, to report the initial 30 months of EU scanning experience. Prospective study of all documented emergency department (ED) ultrasound scans. Results were extracted from written paper reports and/or electronically saved images. Details of scan date, time, type of scan, grade of operator, supervision status (whether supervised by a level 1 competent scanner) and whether the scan was clinical (performed or supervised by a level 1 operator) or training, were recorded. EU scans were reviewed for quality (internal quality assurance) and for diagnostic accuracy (external quality assurance). Between 14 January 2009 and 4 July 2011, 626 scans were performed by 41 operators. 263 (42%) scans were completed outside of normal working hours (09:00 to 17:00). There were 251 abdominal aorta and inferior vena cava scans (40% of all scans) and 198 focused assessment with sonography in trauma scans (32%). The number of scans performed by each operator varied widely. 87 scans (14%) were supervised but the majority (459; 73%) were not. 484 (77%) scans were for training purposes, 124 (20%) were clinical scans and the majority (401; 63%) were performed by either speciality registrars (ST4-6) or specialist registrars (SpR). When the three commonest types of scans performed were analysed, eight false positives and 11 false negatives were identified. Only seven of these were deemed of poor quality and none led to poor patient outcome. Since the acquisition of our ED ultrasound machine and the development of a quality assured training programme, on average 20 scans per month have been performed in the ED, with no known adverse patient outcomes.

Correlated Raman micro-spectroscopy and scanning electron microscopy analyses of flame retardants in environmental samples: a micro-analytical tool for probing chemical composition, origin and spatial distribution.

PubMed

Ghosal, Sutapa; Wagner, Jeff

2013-07-07

We present correlated application of two micro-analytical techniques: scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) and Raman micro-spectroscopy (RMS) for the non-invasive characterization and molecular identification of flame retardants (FRs) in environmental dusts and consumer products. The SEM/EDS-RMS technique offers correlated, morphological, molecular, spatial distribution and semi-quantitative elemental concentration information at the individual particle level with micrometer spatial resolution and minimal sample preparation. The presented methodology uses SEM/EDS analyses for rapid detection of particles containing FR specific elements as potential indicators of FR presence in a sample followed by correlated RMS analyses of the same particles for characterization of the FR sub-regions and surrounding matrices. The spatially resolved characterization enabled by this approach provides insights into the distributional heterogeneity as well as potential transfer and exposure mechanisms for FRs in the environment that is typically not available through traditional FR analysis. We have used this methodology to reveal a heterogeneous distribution of highly concentrated deca-BDE particles in environmental dust, sometimes in association with identifiable consumer materials. The observed coexistence of deca-BDE with consumer material in dust is strongly indicative of its release into the environment via weathering/abrasion of consumer products. Ingestion of such enriched FR particles in dust represents a potential for instantaneous exposure to high FR concentrations. Therefore, correlated SEM/RMS analysis offers a novel investigative tool for addressing an area of important environmental concern.

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.

Energy dispersive X-ray analyses of organelles of NaCI-treated maize root cells

NASA Astrophysics Data System (ADS)

Stelzer, Ralf

1984-04-01

NaCl sensitive plants of Zea mays cv. ADOUR were grown in nutrient solutions with or without NaCl. Frozen, hydrated root-tip tissues were investigated by means of an ETEC scanning electron microscope fitted with a KEVEX energy dispersive X-ray analyser. Morphological details of the gently etched but non-coated surface of the cross fractured specimen were easy to identify and to analyse using an electron beam with a low intensity at 10 kV. X-ray data obtained from cell compartments and organelles as nuclei, nucleoli and mitochondria within individual cells establish typical X-ray spectra. Comparisons of these spectra support the hypothesis that Na + ions are predominantly localized in vacuoles and also to a lesser extent in the cytoplasm, e.g. in small vesicles, but not in other cell organelles. Furthermore the analysed cell compartments show differences in the distribution of Mg, P, S, Cl, K and Ca effected by the addition of NaCl to the growth medium. The X-ray data are discussed in relation to the physiological meaning of a NaCl induced redistribution of elements within individual maize root cells.

Study on processing immiscible materials in zero gravity

NASA Technical Reports Server (NTRS)

Reger, J. L.; Mendelson, R. A.

1975-01-01

An experimental investigation was conducted to evaluate mixing immiscible metal combinations under several process conditions. Under one-gravity, these included thermal processing, thermal plus electromagnetic mixing, and thermal plus acoustic mixing. The same process methods were applied during free fall on the MSFC drop tower facility. The design is included of drop tower apparatus to provide the electromagnetic and acoustic mixing equipment, and a thermal model was prepared to design the specimen and cooling procedure. Materials systems studied were Ca-La, Cd-Ga and Al-Bi; evaluation of the processed samples included the morphology and electronic property measurements. The morphology was developed using optical and scanning electron microscopy and microprobe analyses. Electronic property characterization of the superconducting transition temperatures were made using an impedance change-tuned coil method.

Synthesis, characterization, antimicrobial activity and DFT studies of 2-(pyrimidin-2-ylamino)naphthalene-1,4-dione and its Mn(II), Co(II), Ni(II) and Zn(II) complexes

NASA Astrophysics Data System (ADS)

Chioma, Festus; Ekennia, Anthony C.; Ibeji, Collins U.; Okafor, Sunday N.; Onwudiwe, Damian C.; Osowole, Aderoju A.; Ujam, Oguejiofo T.

2018-07-01

A pyrimidine-based ligand, 2-(pyrimidin-2-ylamino)naphthalene-1,4-dione (L), has been synthesized by the reaction of 2-aminopyrimidine with 2-hydroxy-1,4-napthoquinone. Reaction of the ligand with Ni(II), Co(II), Mn(II) and Zn(II) acetate gave the corresponding metal complexes which were characterized by spectroscopic techniques, (infrared, electronic), elemental analysis, room-temperature magnetometry, conductance measurements and thermogravimetry-differential scanning calorimetry (TG-DSC) analyses. The room-temperature magnetic data and electronic spectral measurements of the complexes gave evidence of 4-coordinate square planar/tetrahedral geometry. The thermal analyses values obtained indicated the monohydrate complexes. The antimicrobial screening of the compounds showed mild to very good results. The Mn(II) complex showed the best result within in the range of 11.5-29 mm. The electronic, structural and spectroscopic properties of the complexes were further discussed using density functional theory. Molecular docking studies showed significant binding affinity with the drug targets and the metal complexes have potentials to be used as drugs.

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.

Comparison of nitrogen adsorption and transmission electron microscopy analyses for structural characterization of carbon nanotubes

NASA Astrophysics Data System (ADS)

Abbaslou, Reza Malek; Vosoughi, Vahid; Dalai, Ajay K.

2017-10-01

Carbon nanotubes (CNTs) are different from other porous substrates such as activated carbon due to their high external surfaces. This structural feature can lead in some uncertainties in the results of nitrogen adsorption analysis for characterization of CNTs. In this paper, the results of microscopic analyses and nitrogen adsorption method for characterization of carbon nanotubes were compared. Five different types of CNTs with different structures were either synthesized or purchased. The CNT samples were characterized by high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) and N2 adsorption analysis. The comparisons between the results from the microscopic analyses and N2 adsorption showed that the total pore volume and BET surface measurements include the internal and external porosity of CNTs. Therefore, the interpretation of N2 adsorption data required accurate TEM analysis. In addition, the evaluation of pore size distribution curves from all CNT samples in this study and several instances in the literature revealed the presence of a common peak in the range of 2-5 nm. This peak does not explain the inner pore size distribution. The presence of this common peak can be attributed to the strong adsorption of N2 on the junction of touched and crossed nanotubes.

TAKASAGO-6 apparatus for cryogenic coherent X-ray diffraction imaging of biological non-crystalline particles using X-ray free electron laser at SACLA.

PubMed

Kobayashi, Amane; Sekiguchi, Yuki; Takayama, Yuki; Oroguchi, Tomotaka; Shirahama, Keiya; Torizuka, Yasufumi; Manoda, Masahiro; Nakasako, Masayoshi; Yamamoto, Masaki

2016-05-01

Coherent X-ray diffraction imaging (CXDI) is a technique for structure analyses of non-crystalline particles with dimensions ranging from micrometer to sub-micrometer. We have developed a diffraction apparatus named TAKASAGO-6 for use in single-shot CXDI experiments of frozen-hydrated non-crystalline biological particles at cryogenic temperature with X-ray free electron laser pulses provided at a repetition rate of 30 Hz from the SPring-8 Angstrom Compact free-electron LAser. Specimen particles are flash-cooled after being dispersed on thin membranes supported by specially designed disks. The apparatus is equipped with a high-speed translation stage with a cryogenic pot for raster-scanning of the disks at a speed higher than 25 μm/33 ms. In addition, we use devices assisting the easy transfer of cooled specimens from liquid-nitrogen storages to the cryogenic pot. In the current experimental procedure, more than 20 000 diffraction patterns can be collected within 1 h. Here we report the key components and performance of the diffraction apparatus. Based on the efficiency of the diffraction data collection and the structure analyses of metal particles, biological cells, and cellular organelles, we discuss the future application of this diffraction apparatus for structure analyses of biological specimens.

Gas chromatography/chemical ionization triple quadrupole mass spectrometry analysis of anabolic steroids: ionization and collision-induced dissociation behavior.

PubMed

Polet, Michael; Van Gansbeke, Wim; Van Eenoo, Peter; Deventer, Koen

2016-02-28

The detection of new anabolic steroid metabolites and new designer steroids is a challenging task in doping analysis. Switching from electron ionization gas chromatography triple quadrupole mass spectrometry (GC/EI-MS/MS) to chemical ionization (CI) has proven to be an efficient way to increase the sensitivity of GC/MS/MS analyses and facilitate the detection of anabolic steroids. CI also extends the possibilities of GC/MS/MS analyses as the molecular ion is retained in its protonated form due to the softer ionization. In EI it can be difficult to find previously unknown but expected metabolites due to the low abundance or absence of the molecular ion and the extensive (and to a large extent unpredictable) fragmentation. The main aim of this work was to study the CI and collision-induced dissociation (CID) behavior of a large number of anabolic androgenic steroids (AAS) as their trimethylsilyl derivatives in order to determine correlations between structures and CID fragmentation. Clarification of these correlations is needed for the elucidation of structures of unknown steroids and new metabolites. The ionization and CID behavior of 65 AAS have been studied using GC/CI-MS/MS with ammonia as the reagent gas. Glucuronidated AAS reference standards were first hydrolyzed to obtain their free forms. Afterwards, all the standards were derivatized to their trimethylsilyl forms. Full scan and product ion scan analyses were used to examine the ionization and CID behavior. Full scan and product ion scan analyses revealed clear correlations between AAS structure and the obtained mass spectra. These correlations were confirmed by analysis of multiple hydroxylated, methylated, chlorinated and deuterated analogs. AAS have been divided into three groups according to their ionization behavior and into seven groups according to their CID behavior. Correlations between fragmentation and structure were revealed and fragmentation pathways were postulated. Copyright © 2016 John Wiley & Sons, Ltd.

3-dimensional electron microscopic imaging of the zebrafish olfactory bulb and dense reconstruction of neurons.

PubMed

Wanner, Adrian A; Genoud, Christel; Friedrich, Rainer W

2016-11-08

Large-scale reconstructions of neuronal populations are critical for structural analyses of neuronal cell types and circuits. Dense reconstructions of neurons from image data require ultrastructural resolution throughout large volumes, which can be achieved by automated volumetric electron microscopy (EM) techniques. We used serial block face scanning EM (SBEM) and conductive sample embedding to acquire an image stack from an olfactory bulb (OB) of a zebrafish larva at a voxel resolution of 9.25×9.25×25 nm 3 . Skeletons of 1,022 neurons, 98% of all neurons in the OB, were reconstructed by manual tracing and efficient error correction procedures. An ergonomic software package, PyKNOSSOS, was created in Python for data browsing, neuron tracing, synapse annotation, and visualization. The reconstructions allow for detailed analyses of morphology, projections and subcellular features of different neuron types. The high density of reconstructions enables geometrical and topological analyses of the OB circuitry. Image data can be accessed and viewed through the neurodata web services (http://www.neurodata.io). Raw data and reconstructions can be visualized in PyKNOSSOS.

3-dimensional electron microscopic imaging of the zebrafish olfactory bulb and dense reconstruction of neurons

PubMed Central

Wanner, Adrian A.; Genoud, Christel; Friedrich, Rainer W.

2016-01-01

Large-scale reconstructions of neuronal populations are critical for structural analyses of neuronal cell types and circuits. Dense reconstructions of neurons from image data require ultrastructural resolution throughout large volumes, which can be achieved by automated volumetric electron microscopy (EM) techniques. We used serial block face scanning EM (SBEM) and conductive sample embedding to acquire an image stack from an olfactory bulb (OB) of a zebrafish larva at a voxel resolution of 9.25×9.25×25 nm3. Skeletons of 1,022 neurons, 98% of all neurons in the OB, were reconstructed by manual tracing and efficient error correction procedures. An ergonomic software package, PyKNOSSOS, was created in Python for data browsing, neuron tracing, synapse annotation, and visualization. The reconstructions allow for detailed analyses of morphology, projections and subcellular features of different neuron types. The high density of reconstructions enables geometrical and topological analyses of the OB circuitry. Image data can be accessed and viewed through the neurodata web services (http://www.neurodata.io). Raw data and reconstructions can be visualized in PyKNOSSOS. PMID:27824337

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

Analysis of rare earth elements in coal fly ash using laser ablation inductively coupled plasma mass spectrometry and scanning electron microscopy

NASA Astrophysics Data System (ADS)

Thompson, Robert L.; Bank, Tracy; Montross, Scott; Roth, Elliot; Howard, Bret; Verba, Circe; Granite, Evan

2018-05-01

Reference standard NIST SRM 1633b and FA 345, a fly ash sample from an eastern U.S. coal power plant, were analyzed to determine and quantify the mineralogical association of rare earth elements (REE). These analyses were completed using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and a scanning electron microscope, equipped with an energy-dispersive X-ray spectrometer (SEM-EDS). Internal standardization was avoided by quantifying elemental concentrations by normalizing to 100% oxides. Mineral grains containing elevated REE concentrations were found in diverse chemical environments, but were most commonly found in regions where Al and Si were predominant. Dividing the spot analyses into time segments yielded plots that showed the REE content changing over time as individual mineral grains were being ablated. SEM-EDS images of FA 345 confirmed the trends that were found in the LA-ICP-MS results. Small grains of apatite, monazite, or zircon were frequently observed as free mineral grains or embedded in amorphous aluminosilicate glass and were not associated with ferrous particles. This finding is consistent with previous reports that magnetic enrichment may be an effective way of concentrating non-magnetic REE phases. Furthermore, aggressive mechanical and chemical-based separation schemes will be required to separate and recover REE from aluminosilicate glass.

Development and characterization of decellularized human nasoseptal cartilage matrix for use in tissue engineering.

PubMed

Graham, M Elise; Gratzer, Paul F; Bezuhly, Michael; Hong, Paul

2016-10-01

Reconstruction of cartilage defects in the head and neck can require harvesting of autologous cartilage grafts, which can be associated with donor site morbidity. To overcome this limitation, tissue-engineering approaches may be used to generate cartilage grafts. The objective of this study was to decellularize and characterize human nasoseptal cartilage with the aim of generating a biological scaffold for cartilage tissue engineering. Laboratory study using nasoseptal cartilage. Remnant human nasoseptal cartilage specimens were collected and subjected to a novel decellularization treatment. The decellularization process involved several cycles of enzymatic detergent treatments. For characterization, decellularized and fresh (control) specimens underwent histological, biochemical, and mechanical analyses. Scanning electron microscopy and biocompatibility assay were also performed. The decellularization process had minimal effect on glycosaminoglycan content of the cartilage extracellular matrix. Deoxyribonucleic acid (DNA) analysis revealed the near-complete removal of genomic DNA from decellularized tissues. The effectiveness of the decellularization process was also confirmed on histological and scanning electron microscopic analyses. Mechanical testing results showed that the structural integrity of the decellularized tissue was maintained, and biocompatibility was confirmed. Overall, the current decellularization treatment resulted in significant reduction of genetic/cellular material with preservation of the underlying extracellular matrix structure. This decellularized material may serve as a potential scaffold for cartilage tissue engineering. N/A. Laryngoscope, 126:2226-2231, 2016. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

Development of core-shell coaxially electrospun composite PCL/chitosan scaffolds.

PubMed

Surucu, Seda; Turkoglu Sasmazel, Hilal

2016-11-01

This study was related to combining of synthetic Poly (ε-caprolactone) (PCL) and natural chitosan polymers to develop three dimensional (3D) PCL/chitosan core-shell scaffolds for tissue engineering applications. The scaffolds were fabricated with coaxial electrospinning technique and the characterizations of the samples were done by thickness and contact angle (CA) measurements, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray Photoelectron Spectroscopy (XPS) analyses, mechanical and PBS absorption and shrinkage tests. The average inter-fiber diameter values were calculated for PCL (0.717±0.001μm), chitosan (0.660±0.007μm) and PCL/chitosan core-shell scaffolds (0.412±0.003μm), also the average inter-fiber pore size values exhibited decreases of 66.91% and 61.90% for the PCL and chitosan scaffolds respectively, compared to PCL/chitosan core-shell ones. XPS analysis of the PCL/chitosan core-shell structures exhibited the characteristic peaks of PCL and chitosan polymers. The cell culture studies (MTT assay, Confocal Laser Scanning Microscope (CLSM) and SEM analyses) carried out with L929 ATCC CCL-1 mouse fibroblast cell line proved that the biocompatibility performance of the scaffolds. The obtained results showed that the created micro/nano fibrous structure of the PCL/chitosan core-shell scaffolds in this study increased the cell viability and proliferation on/within scaffolds. 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

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.

Raman-in-SEM, a multimodal and multiscale analytical tool: performance for materials and expertise.

PubMed

Wille, Guillaume; Bourrat, Xavier; Maubec, Nicolas; Lahfid, Abdeltif

2014-12-01

The availability of Raman spectroscopy in a powerful analytical scanning electron microscope (SEM) allows morphological, elemental, chemical, physical and electronic analysis without moving the sample between instruments. This paper documents the metrological performance of the SEMSCA commercial Raman interface operated in a low vacuum SEM. It provides multiscale and multimodal analyses as Raman/EDS, Raman/cathodoluminescence or Raman/STEM (STEM: scanning transmission electron microscopy) as well as Raman spectroscopy on nanomaterials. Since Raman spectroscopy in a SEM can be influenced by several SEM-related phenomena, this paper firstly presents a comparison of this new tool with a conventional micro-Raman spectrometer. Then, some possible artefacts are documented, which are due to the impact of electron beam-induced contamination or cathodoluminescence contribution to the Raman spectra, especially with geological samples. These effects are easily overcome by changing or adapting the Raman spectrometer and the SEM settings and methodology. The deletion of the adverse effect of cathodoluminescence is solved by using a SEM beam shutter during Raman acquisition. In contrast, this interface provides the ability to record the cathodoluminescence (CL) spectrum of a phase. In a second part, this study highlights the interest and efficiency of the coupling in characterizing micrometric phases at the same point. This multimodal approach is illustrated with various issues encountered in geosciences. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enhancement of Spartium junceum L. fibres properties

NASA Astrophysics Data System (ADS)

Kovačević, Z.; Bischof, S.; Antonović, A.

2017-10-01

Properties of lignocellulosic Spartium junceum L. (SJL) fibres were investigated in order to use them as reinforcement in composite material production. The fibres were obtained by microwave maceration process and additionally modified with NaOH, nanoclay and citric acid with the aim to improve their mechanical, thermal and other physical-chemical properties. Tensile and thermal properties of these natural fibres were enhanced by the different modification treatment which is investigated by the Vibrodyn/Vibroskop method and thermogravimetric analysis (TGA), whilst determination of chemical composition and fibre’s surface properties were explored using scanning electron microscope (SEM), electron dispersive spectroscopy (EDS) and elektrokinetic analyser. All the results show great improvement of nanoclay/citric acid modified SJL properties.

Preparation and characterization of oriented silica nanowires

NASA Astrophysics Data System (ADS)

Sun, S. H.; Meng, G. W.; Zhang, M. G.; Tian, Y. T.; Xie, T.; Zhang, L. D.

2003-11-01

Large-scale of oriented closely packed silica nanowire bunches have been synthesized by using large size (1-10 μm in diameter), low melting point tin droplets as catalyst on silicon wafers at 980 °C. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses show that the amorphous silica nanowires have lengths of 50-100 μm and diameters of 100-200 nm. Unlike any previous observed results using high melting point metal (such as gold and iron) as catalyst, the Sn catalyst growth exhibits many interesting phenomena. Each Sn ball can simultaneously catalyze the growth of many silica nanowires, which is quite different from the conventional vapor-liquid-solid process.

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.

Strain analysis from nano-beam electron diffraction: Influence of specimen tilt and beam convergence.

PubMed

Grieb, Tim; Krause, Florian F; Schowalter, Marco; Zillmann, Dennis; Sellin, Roman; Müller-Caspary, Knut; Mahr, Christoph; Mehrtens, Thorsten; Bimberg, Dieter; Rosenauer, Andreas

2018-07-01

Strain analyses from experimental series of nano-beam electron diffraction (NBED) patterns in scanning transmission electron microscopy are performed for different specimen tilts. Simulations of NBED series are presented for which strain analysis gives results that are in accordance with experiment. This consequently allows to study the relation between measured strain and actual underlying strain. A two-tilt method which can be seen as lowest-order electron beam precession is suggested and experimentally implemented. Strain determination from NBED series with increasing beam convergence is performed in combination with the experimental realization of a probe-forming aperture with a cross inside. It is shown that using standard evaluation techniques, the influence of beam convergence on spatial resolution is lower than the influence of sharp rings around the diffraction disc which occur at interfaces and which are caused by the tails of the intensity distribution of the electron probe. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of Electron Beam Irradiation on Structural and Optical Properties of Cu-Doped In2O3 Films Prepared by RF Magnetron Sputtering

NASA Astrophysics Data System (ADS)

Krishnan, R. Reshmi; Sanjeev, Ganesh; Prabhu, Radhakrishna; Pillai, V. P. Mahadevan

2018-02-01

Undoped and Cu-doped In2O3 films were prepared by radiofrequency magnetron sputtering technique. The effects of Cu doping and high-energy electron beam irradiation on the structural and optical properties of as-prepared films were investigated using techniques such as x-ray diffraction, x-ray photoelectron spectroscopy (XPS), lateral scanning electron microscopic image analysis, energy-dispersive x-ray (EDX) spectroscopy, micro-Raman, and ultraviolet-visible (UV-vis) spectroscopy. Moderate doping of Cu in In2O3 enhanced the intensity of (222) peak, indicating alignment of crystalline grains along <111>. Electron beam irradiation promoted orientation of crystalline grains along <111> in undoped and moderately Cu-doped films. EDX spectroscopic and XPS analyses revealed incorporation of Cu2+ ions in the lattice. The transmittance of Cu-doped films decreased with e-beam irradiation. Systematic reduction of the bandgap energy with increase in Cu doping concentration was seen in unirradiated and electron-beam-irradiated films.

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.

Structural and optical investigation on the wings of Idea malabarica (Moore, 1877).

PubMed

Sackey, Juliet; Nuru, Zebib Y; Sone, Bertrand Tumbain; Maaza, Malik

2017-02-01

The nanostructures on the wings of Idea malabarica (Moore, 1877) were analysed using scanning electron microscopy, energy dispersive X-ray spectroscopy, atomic force microscopy, Fourier transform-infrared spectroscopy, and reflectance measurements. The chemical and morphological analyses revealed the chitin-based intricate nanostructures. The influence of the nanostructures on the wetting characteristics of the wing was investigated using optical imaging. Applying the Maxwell-Garnet approximation to the porosities within the nanostructures, the refractive indices, which relate the reflectance response, were estimated. It was concluded that the colour seen on the wings of the Idea malabarica originate from the nanostructural configurations of the chitin-based structures and the embedded pigment.

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

Multivariate statistical analysis of low-voltage EDS spectrum images

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

Anderson, I.M.

1998-03-01

Whereas energy-dispersive X-ray spectrometry (EDS) has been used for compositional analysis in the scanning electron microscope for 30 years, the benefits of using low operating voltages for such analyses have been explored only during the last few years. This paper couples low-voltage EDS with two other emerging areas of characterization: spectrum imaging and multivariate statistical analysis. The specimen analyzed for this study was a finished Intel Pentium processor, with the polyimide protective coating stripped off to expose the final active layers.

Studies of Al-Ti Alloys by SEM

NASA Astrophysics Data System (ADS)

Yildiz, K.; Atici, Y.; Keşlİ Oǧlu, K.; Yaşar, E.

2007-04-01

Al-Ti (1, 2 wt. %) alloys were investigated by Scanning Electron Microscopy (SEM). SEM observations and energy-dispersive x-ray analyses (EDX) showed that the phase structure of Al-Ti (1 %) alloy at 165 μm/s is composed of Al matrix and C, Ni, Fe and Si particles and the Al-Ti (1 %) alloys at 16 and 8 μm/s have only the Al matrix and C particles. It was also found that the Al-Ti (2 %) form the Al matrix and intermetallic TiAl.

Studies of the Ossicles from the Ciliate Protozoan Spirostomum ambiguum

NASA Astrophysics Data System (ADS)

Takagui, Regina; Silveira, Marina

1999-09-01

Spirostomum ambiguum is able to concentrate intracellular deposits of calcium phosphate. This mineralization process is dependent on the age of the culture and can be stimulated by an applied piezoelectric potential. Crystalline deposits induced to form in laboratory cultures were analysed both in situ and after isolation from the cells, using transmission and scanning electron microscopies, energy dispersive microanalysis, and optical spectrophotometry. The ratio of Ca:P (1.57±0.01) fits with the expected value for hydroxyapatite.

Formation of nanoparticles from thin silver films irradiated by laser pulses in air

NASA Astrophysics Data System (ADS)

Nastulyavichus, A. A.; Smirnov, N. A.; Kudryashov, S. I.; Ionin, A. A.; Saraeva, I. N.; Busleev, N. I.; Rudenko, A. A.; Khmel'nitskii, R. A.; Zayarnyi, D. A.

2018-03-01

Some specific features of the transport of silver nanoparticles onto a SiO2 substrate under focused nanosecond IR laser pulses is experimentally investigated. A possibility of obtaining silver coatings is demonstrated. The formation of silver nanostructures as a result of pulsed laser ablation in air is studied. Nanoparticles are formed by exposing a silver film to radiation of an HTF MARK (Bulat) laser marker (λ = 1064 nm). The thus prepared nanoparticles are analysed using scanning electron microscopy and optical spectroscopy.

Coarsening behaviour of M23C6 carbides in creep-resistant steel exposed to high temperatures

NASA Astrophysics Data System (ADS)

Godec, M.; Skobir Balantič, D. A.

2016-07-01

High operating temperatures can have very deleterious effects on the long-term performance of high-Cr, creep-resistant steels used, for example, in the structural components of power plants. For the popular creep-resistant steel X20CrMoV12.1 we analysed the processes of carbide growth using a variety of analytical techniques: transmission electron microscopy (TEM) and diffraction (TED), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). The evolution of the microstructure after different aging times was the basis for a much better understanding of the boundary-migration processes and the growth of the carbides. We present an explanation as to why some locations are preferential for this growth, and using EBSD we were able to define the proper orientational relationship between the carbides and the matrix.

APPLICATIONS OF CATHODOLUMINESCENCE OF QUARTZ AND FELDSPAR TO SEDIMENTARY PETROLOGY.

USGS Publications Warehouse

Ruppert, Leslie F.

1987-01-01

Cathodoluminescence (CL), the emission of visible light during electron bombardment, was first used in sandstone petrology in the mid-1960's. CL techniques are especially useful for determining the origin and source of quartz and feldspar, two of the most common constituents in clastic rocks. CL properties of both minerals are dependent on their temperature of crystallization, duration of cooling, and/or history of deformation. Detrital quartz and feldspar are typically derived from igneous and metamorphic sources and luminesce in the visible range whereas authigenic quartz and feldspar form at low temperatures and do not luminesce. Quantification of luminescent and non-luminescent quartz and feldspar with the scanning electron microscope, electron microprobe, or a commercial CL device can allow for the determination of origin, diagenesis, and source of clastic rocks when used in conjunction with field and other petrographic analyses.

Balamuthia mandrillaris: Further morphological observations of trophozoites by light, scanning and transmission electron microscopy.

PubMed

González-Robles, Arturo; Lares-Villa, Fernando; Lares-Jiménez, Luis Fernando; Omaña-Molina, Maritza; Salazar-Villatoro, Lizbeth; Martínez-Palomo, Adolfo

2015-10-01

Additional morphological features of Balamuthia mandrillaris observed by light and electron microscopy are reported. Trophozoites were extremely pleomorphic: their cell shapes ranged from rounded to elongated and sometimes they appeared exceptionally stretched out and branched. By transmission electron microscopy it was possible to observe two different cytoplasmic areas, the ectoplasm and the endoplasm and often sections of rough endoplasmic reticulum were found in the transition zone. The cytoplasm was very fibrogranular and most of the organelles typically found in eukaryotic cells were observed. A particular finding was the presence of numerous mitochondria with a different structure from those of other free-living amoebae. The observations reported here may reinforce the morphological knowledge of this amoeba and provide a background for further analyses. Copyright © 2015 Elsevier Inc. All rights reserved.

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.

New Cu-Free Ti-Based Composites with Residual Amorphous Matrix

PubMed Central

Nicoara, Mircea; Locovei, Cosmin; Șerban, Viorel Aurel; Parthiban, R.; Calin, Mariana; Stoica, Mihai

2016-01-01

Titanium-based bulk metallic glasses (BMGs) are considered to have potential for biomedical applications because they combine favorable mechanical properties and good biocompatibility. Copper represents the most common alloying element, which provides high amorphization capacity, but reports emphasizing cytotoxic effects of this element have risen concerns about possible effects on human health. A new copper-free alloy with atomic composition Ti42Zr10Pd14Ag26Sn8, in which Cu is completely replaced by Ag, was formulated based on Morinaga’s d-electron alloy design theory. Following this theory, the actual amount of alloying elements, which defines the values of covalent bond strength Bo and d-orbital energy Md, situates the newly designed alloy inside the BMG domain. By mean of centrifugal casting, cylindrical rods with diameters between 2 and 5 mm were fabricated from this new alloy. Differential scanning calorimetry (DSC) and X-rays diffraction (XRD), as well as microstructural analyses using optical and scanning electron microscopy (OM/SEM) revealed an interesting structure characterized by liquid phase-separated formation of crystalline Ag, as well as metastable intermetallic phases embedded in residual amorphous phases. PMID:28773455

Submolecular resolution in scanning probe images of Sn-phthalocyanines on Cu(1 0 0) using metal tips

NASA Astrophysics Data System (ADS)

Buchmann, Kristof; Hauptmann, Nadine; Foster, Adam S.; Berndt, Richard

2017-10-01

Single Sn-phthalocyanine (SnPc) molecules adsorb on Cu(1 0 0) with the Sn ion above (Sn-up) or below (Sn-down) the molecular plane. Here we use a combination of atomic force microscopy (AFM), scanning tunnelling microscopy (STM) and first principles calculations to understand the adsorption configuration and origin of observed contrast of molecules in the Sn-down state. AFM with metallic tips images the pyrrole nitrogen atoms in these molecules as attractive features while STM reveals a chirality of the electronic structure of the molecules close to the Fermi level E_F, which is not observed in AFM. Using density functional theory calculations, the origin of the submolecular contrast is analysed and, while the electrostatic forces turn out to be negligible, the van der Waals interaction between the phenyl rings of SnPc and the substrate deform the molecule, push the pyrrole nitrogen atoms away from the substrate and thus induce the observed submolecular contrast. Simulated STM images reproduce the chirality of the electronic structure near E_F.

Synthesis of TiO2 Nanoparticle and its phase Transition

NASA Astrophysics Data System (ADS)

Mangrola, M. H.; Joshi, V. G.; Parmar, B. H.

2011-12-01

Here we report the synthesis of titanium dioxide (TiO2) nanoparticles and study of its phase transition from anataze to rutile. Titanium dioxide (TiO2) nanoparticles have been prepared by hydrolysis of Titanium isopropoxide an aqueous solution with constant value of pH 2 and peptizing the resultant suspension gel(white-Blue) and calcinate gel at different temperature. Structures of synthetic samples of TiO2 have been examined by X-ray diffraction (XRD) and scanning electron microscope (SEM). The anatase-rutile transition has been a popular topic due to its interest to scientific and engineering fields. . Here we have seen that the 100 °C calcinate powder consist of anatase fine crystalline phase with a particle size 14 to 15 nm. The prepared TiO2 nanoparticles have uniform size and morphology, and the phase transformation kinetics of obtained material was studied by interpretation of the X-ray diffraction patterns peaks. The phase transform occurred from anatase to rutile at calcinate temperature up to 600 °C. A very fine network texture made from uniform nanoparticles was revealed by scanning electron microscopy (SEM) analyses.

Electrodeposition of Ni and CeO₂/Ni Nanotubes for Hydrogen Evolution Reaction Electrode.

PubMed

Du, Xiaoqing; Yang, Yumeng; Yi, Chenxi; Chen, Yu; Cai, Chao; Zhang, Zhao

2018-07-01

Ni NTs and CeO2-Ni nanotubes (NTs) have been prepared by galvanostatic electrodeposition in anodic aluminum oxide (AAO) Templates. Scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopic (EDS) and X-ray Diffraction (XRD) are used to characterize the prepared NTs. The results showed that the preparation process of CeO2-Ni NTs was accompanied by the formation of many new phases CeNix (x = 1, 2, 3.5 or 5) and preferential orientation crystal face of Ni in CeO2-Ni NTs is 〈111〉, which is different from that Ni 〈200〉 in Ni NTs. Then linear scan voltammetry (LSV) is applied to test the electrocatalytic activity for hydrogen revolution reaction (HER) of the two electrodes in 1 M NaCl aqueous solution and find that both of the two materials exhibited good performance. Finally, the kinetics analyses from the HER process showed that Tafel slope b was mainly dependent on phase composition and electric conductivity of the electrode, while j0 was mainly dependent on its real specific surface area.

Nanostructures formed by cyclodextrin covered procainamide through supramolecular self assembly - Spectral and molecular modeling study

NASA Astrophysics Data System (ADS)

Rajendiran, N.; Mohandoss, T.; Sankaranarayanan, R. K.

2015-02-01

Inclusion complexation behavior of procainamide (PCA) with two cyclodextrins (α-CD and β-CD) were analyzed by absorption, fluorescence, scanning electron microscope (SEM), transmission electron microscope (TEM), Raman image, FT-IR, differential scanning colorimeter (DSC), Powder X ray diffraction (XRD) and 1H NMR. Blue shift was observed in β-CD whereas no significant spectral shift observed in α-CD. The inclusion complex formation results suggest that water molecules also present in the inside of the CD cavity. The present study revealed that the phenyl ring of the PCA drug is entrapped in the CD cavity. Cyclodextrin studies show that PCA forms 1:2 inclusion complex with α-CD and β-CD. PCA:α-CD complex form nano-sized particles (46 nm) and PCA:β-CD complex form self-assembled to micro-sized tubular structures. The shape-shifting of 2D nanosheets into 1D microtubes by simple rolling mechanism were analysed by micro-Raman and TEM images. Thermodynamic parameters (ΔH, ΔG and ΔS) of inclusion process were determined from semiempirical PM3 calculations.

Study of the surfactant role in latex-aerogel systems by scanning transmission electron microscopy on aqueous suspensions.

PubMed

Perret, A; Foray, G; Masenelli-Varlot, K; Maire, E; Yrieix, B

2018-01-01

For insulation applications, boards thinner than 2 cm are under design with specific thermal conductivities lower than 15 mW m -1  K -1 . This requires binding slightly hydrophobic aerogels which are highly nanoporous granular materials. To reach this step and ensure insulation board durability at the building scale, it is compulsory to design, characterise and analyse the microstructure at the nanoscale. It is indeed necessary to understand how the solid material is formed from a liquid suspension. This issue is addressed in this paper through wet-STEM experiments carried out in an Environmental Scanning Electron Microscope (ESEM). Latex-surfactant binary blends and latex-surfactant-aerogel ternary systems are studied, with two different surfactants of very different chemical structures. Image analysis is used to distinguish the different components and get quantitative morphological parameters which describe the sample architecture. The evolution of such morphological parameters during water evaporation permits a good understanding of the role of the surfactant. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Crystalline gamma-Al2O3 physical vapour deposition-coating for steel thixoforging tools.

PubMed

Bobzin, K; Hirt, G; Bagcivan, N; Khizhnyakova, L; Ewering, M

2011-10-01

The process of thixoforming, which has been part of many researches during the last decades, combines the advantages of forging and casting for the shaping of metallic components. But due to the high temperatures of semi-solid steel alloys high demands on the tools are requested. To resists the thermal and mechanical loads (wear, friction, thermal and thermomechanical fatigue) protecting thin films are necessary. In this regard crystalline gamma-Al2O3 deposited via Physical Vapour Deposition (PVD) is a promising candidate: It exhibits high thermal stability, high oxidation resistance and high hot hardness. In the present work the application of a (Ti, Al)N/gamma-Al2O3 coating deposited by means of Magnetron Sputter Ion Plating in an industrial coating unit is presented. The coating was analysed by means of Rockwell test, nanoindentation, and Scanning Electron Microscopy (SEM). The coated tool was tested in thixoforging experiments with steel grade X210CrW12 (AlSI D6). The surface of the coated dies was examined with Scanning Electron Microscope (SEM) after 22, 42, 90 and 170 forging cycles.

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.

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.

Alkali-aggregate reaction under the influence of deicing salts in the Hokuriku district, Japan

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

Katayama, Tetsuya; Tagami, Masahiko; Sarai, Yoshinori

2004-11-15

Concrete cores taken from highway bridges and culverts undergoing alkali-silica reaction (ASR) were investigated petrographically by means of core scanning, point counting, polarizing microscopy, scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), electron-probe microanalysis with energy-dispersive spectrometry, in conjunction with wet chemical analyses and expansion tests. Field damage was roughly proportional to the content of andesite in the gravel aggregates due to the presence of highly reactive cristobalite and tridymite. Electron-probe microanalyzer analysis of unhydrated cement phases in the concrete revealed that the cement used had contained at least 0.5% to 1.0% alkali (Na{sub 2}Oeq) and that both the aggregatesmore » and the deicing salts had supplied part of the water-soluble alkali to concrete toward the threshold of producing ASR (Na{sub 2}O{sub eq} 3.0 kg/m{sup 3}). An accelerated concrete core expansion test (1 M NaOH, 80 deg. C) of the damaged structures mostly gave core expansions of >0.10% at 21 days (or >0.05% at 14 days), nearly comparable to those of a slow expansion test with saturated NaCl solution (50 deg. C, 91 days) which produced Cl-containing ASR gel.« less

Electron transport in stepped Bi2Se3 thin films

NASA Astrophysics Data System (ADS)

Bauer, S.; Bobisch, C. A.

2017-08-01

We analyse the electron transport in a 16 quintuple layer thick stepped Bi2Se3 film grown on Si(1 1 1) by means of scanning tunnelling potentiometry (STP) and multi-point probe measurements. Scanning tunnelling microscopy images reveal that the local structure of the Bi2Se3 film is dominated by terrace steps and domain boundaries. From a microscopic study on the nm scale by STP, we find a mostly linear gradient of the voltage on the Bi2Se3 terraces which is interrupted by voltage drops at the position of the domain boundaries. The voltage drops indicate that the domain boundaries are scatterers for the electron transport. Macroscopic resistance measurements (2PP and in-line 4PP measurement) on the µm scale support the microscopic results. An additional rotational square 4PP measurement shows an electrical anisotropy of the sheet conductance parallel and perpendicular to the Bi2Se3 steps of about 10%. This is a result of the anisotropic step distribution at the stepped Bi2Se3 surface while domain boundaries are distributed isotropically. The determined value of the conductivity of the Bi2Se3 steps of about 1000 S cm-1 verifies the value of an earlier STP study.

Focussed Ion Beam Milling and Scanning Electron Microscopy of Brain Tissue

PubMed Central

Knott, Graham; Rosset, Stéphanie; Cantoni, Marco

2011-01-01

This protocol describes how biological samples, like brain tissue, can be imaged in three dimensions using the focussed ion beam/scanning electron microscope (FIB/SEM). The samples are fixed with aldehydes, heavy metal stained using osmium tetroxide and uranyl acetate. They are then dehydrated with alcohol and infiltrated with resin, which is then hardened. Using a light microscope and ultramicrotome with glass knives, a small block containing the region interest close to the surface is made. The block is then placed inside the FIB/SEM, and the ion beam used to roughly mill a vertical face along one side of the block, close to this region. Using backscattered electrons to image the underlying structures, a smaller face is then milled with a finer ion beam and the surface scrutinised more closely to determine the exact area of the face to be imaged and milled. The parameters of the microscope are then set so that the face is repeatedly milled and imaged so that serial images are collected through a volume of the block. The image stack will typically contain isotropic voxels with dimenions as small a 4 nm in each direction. This image quality in any imaging plane enables the user to analyse cell ultrastructure at any viewing angle within the image stack. PMID:21775953

Characterisation of metals in the electronic waste of complex mixtures of end-of-life ICT products for development of cleaner recovery technology.

PubMed

Sun, Z H I; Xiao, Y; Sietsma, J; Agterhuis, H; Visser, G; Yang, Y

2015-01-01

Recycling of valuable metals from electronic waste, especially complex mixtures of end-of-life information and communication technology (ICT) products, is of great difficulty due to their complexity and heterogeneity. One of the important reasons is the lack of comprehensive characterisation on such materials, i.e. accurate compositions, physical/chemical properties. In the present research, we focus on developing methodologies for the characterisation of metals in an industrially processed ICT waste. The morphology, particle size distribution, compositional distribution, occurrence, liberation as well as the thermo-chemical properties of the ICT waste were investigated with various characterisation techniques, including X-ray Fluorescence Spectrometry (XRF), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) with energy dispersed spectroscopy (EDS). Due to the high heterogeneity of the material, special sample preparation procedures were introduced to minimise the discrepancies during compositional analyses. As a result, a clearer overview of the ICT waste has been reached. This research provides better understanding of the extractability of each metal and improves the awareness of potential obstacles for extraction. It will lead to smarter decisions during further development of a clean and effective recovery process. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Miniaturized Variable Pressure Scanning Electron Microscope (MVP-SEM) for In-Situ Mars Surface Sample Analysis

NASA Technical Reports Server (NTRS)

Edmunson, J.; Gaskin, J. A.; Jerman, G. A.; Harvey, R. P.; Doloboff, I. J.; Neidholdt, E. L.

2016-01-01

The Miniaturized Variable Pressure Scanning Electron Microscope (MVP-SEM) project, funded by the NASA Planetary Instrument Concepts for the Advancement of Solar System Observations (PICASSO) Research Opportunities in Space and Earth Sciences (ROSES), will build upon previous miniaturized SEM designs and recent advancements in variable pressure SEM's to design and build a SEM to complete analyses of samples on the surface of Mars using the atmosphere as an imaging medium. This project is a collaboration between NASA Marshall Space Flight Center (MSFC), the Jet Propulsion Laboratory (JPL), electron gun and optics manufacturer Applied Physics Technologies, and small vacuum system manufacturer Creare. Dr. Ralph Harvery and environmental SEM (ESEM) inventor Dr. Gerry Danilatos serve as advisors to the team. Variable pressure SEMs allow for fine (nm-scale) resolution imaging and micron-scale chemical study of materials without sample preparation (e.g., carbon or gold coating). Charging of a sample is reduced or eliminated by the gas surrounding the sample. It is this property of ESEMs that make them ideal for locations where sample preparation is not yet feasible, such as the surface of Mars. In addition, the lack of sample preparation needed here will simplify the sample acquisition process and allow caching of the samples for future complementary payload use.

Nanometer-scale characterization of exceptionally preserved bacterial fossils in Paleocene phosphorites from Ouled Abdoun (Morocco).

PubMed

Cosmidis, J; Benzerara, K; Gheerbrant, E; Estève, I; Bouya, B; Amaghzaz, M

2013-03-01

Micrometer-sized spherical and rod-shaped forms have been reported in many phosphorites and often interpreted as microbes fossilized by apatite, based on their morphologic resemblance with modern bacteria inferred by scanning electron microscopy (SEM) observations. This interpretation supports models involving bacteria in the formation of phosphorites. Here, we studied a phosphatic coprolite of Paleocene age originating from the Ouled Abdoun phosphate basin (Morocco) down to the nanometer-scale using focused ion beam milling, transmission electron microscopy (TEM), and scanning transmission x-ray microscopy (STXM) coupled with x-ray absorption near-edge structure spectroscopy (XANES). The coprolite, exclusively composed of francolite (a carbonate-fluroapatite), is formed by the accumulation of spherical objects, delimited by a thin envelope, and whose apparent diameters are between 0.5 and 3 μm. The envelope of the spheres is composed of a continuous crown dense to electrons, which measures 20-40 nm in thickness. It is surrounded by two thinner layers that are more porous and transparent to electrons and enriched in organic carbon. The observed spherical objects are very similar with bacteria encrusting in hydroxyapatite as observed in laboratory experiments. We suggest that they are Gram-negative bacteria fossilized by francolite, the precipitation of which started within the periplasm of the cells. We discuss the role of bacteria in the fossilization mechanism and propose that they could have played an active role in the formation of francolite. This study shows that ancient phosphorites can contain fossil biological subcellular structures as fine as a bacterial periplasm. Moreover, we demonstrate that while morphological information provided by SEM analyses is valuable, the use of additional nanoscale analyses is a powerful approach to help inferring the biogenicity of biomorphs found in phosphorites. A more systematic use of this approach could considerably improve our knowledge and understanding of the microfossils present in the geological record. © 2012 Blackwell Publishing Ltd.

Biocompatibility of bio based calcium carbonate nanocrystals aragonite polymorph on NIH 3T3 fibroblast cell line.

PubMed

Kamba, Abdullahi Shafiu; Ismail, Maznah; Ibrahim, Tengku Azmi Tengku; Zakaria, Zuki Abu Bakar

2014-01-01

Currently, there has been extensive research interest for inorganic nanocrystals such as calcium phosphate, iron oxide, silicone, carbon nanotube and layered double hydroxide as a drug delivery system especially in cancer therapy. However, toxicological screening of such particles is paramount importance before use as delivery carrier. In this study we examine the biocompatibility of CaCO3 nanocrystal on NIH 3T3 cell line. Transmission and field emission scanning electron microscopy (TEM and FESEM) were used for the characterisation of CaCO3 nanocrystals. Cytotoxicity and genotoxic effect of calcium carbonate nanocrystals in cultured mouse embryonic fibroblast NIH 3T3 cell line using various bioassays including MTT, and Neutral red/Trypan blue double-staining assays. LDH, BrdU and reactive oxygen species were used for toxicity analysis. Cellular morphology was examined by scanning electron microscopy (SEM) and confocal fluorescence microscope. The outcome of the analyses revealed a clear rod-shaped aragonite polymorph of calcium carbonate nanocrystal. The analysed cytotoxic and genotoxicity of CaCO3 nanocrystal on NIH 3T3 cells using different bioassays revealed no significance differences as compared to control. A slight decrease in cell viability was noticed when the cells were exposed to higher concentrations of 200 to 400 µg/ml, while increase in ROS generation and LDH released at 200 and 400 µg/ml was observed. The study has shown that CaCO3 nanocrystal is biocompatible and non toxic to NIH 3T3 fibroblast cells. The analysed results offer a promising potential of CaCO3 nanocrystal for the development of intracellular drugs, genes and other macromolecule delivery systems.

Assessment of technical condition of concrete pavement by the example of district road

NASA Astrophysics Data System (ADS)

Linek, M.; Nita, P.; Żebrowski, W.; Wolka, P.

2018-05-01

The article presents the comprehensive assessment of concrete pavement condition. Analyses included the district road located in the swietokrzyskie province, used for 11 years. Comparative analyses were conducted twice. The first analysis was carried out after 9 years of pavement operation, in 2015. In order to assess the extent of pavement degradation, the tests were repeated in 2017. Within the scope of field research, the traffic intensity within the analysed road section was determined. Visual assessment of pavement condition was conducted, according to the guidelines included in SOSN-B. Visual assessment can be extended by ground-penetrating radar measurements which allow to provide comprehensive assessment of the occurred structure changes within its entire thickness and length. The assessment included also performance parameters, i.e. pavement regularity, surface roughness and texture. Extension of test results by the assessment of changes in internal structure of concrete composite and structure observations by means of Scanning Electron Microscope allow for the assessment of parameters of internal structure of hardened concrete. Supplementing the observations of internal structure by means of computed tomography scan provides comprehensive information of possible discontinuities and composite structure. According to the analysis of the obtained results, conclusions concerning the analysed pavement condition were reached. It was determined that the pavement is distinguished by high performance parameters, its condition is good and it does not require any repairs. Maintenance treatment was suggested in order to extend the period of proper operation of the analysed pavement.

The role of biomineralization in microbiologically influenced corrosion

NASA Technical Reports Server (NTRS)

Little, B.; Wagner, P.; Hart, K.; Ray, R.; Lavoie, D.; Nealson, K.; Aguilar, C.

1998-01-01

Synthetic iron oxides (goethite, alpha-FeO.OH; hematite, Fe2O3; and ferrihydrite, Fe(OH)3) were used as model compounds to simulate the mineralogy of surface films on carbon steel. Dissolution of these oxides exposed to pure cultures of the metal-reducing bacterium, Shewanella putrefaciens, was followed by direct atomic absorption spectroscopy measurement of ferrous iron coupled with microscopic analyses using confocal laser scanning and environmental scanning electron microscopies. During an 8-day exposure the organism colonized mineral surfaces and reduced solid ferric oxides to soluble ferrous ions. Elemental composition, as monitored by energy dispersive x-ray spectroscopy, indicated mineral replacement reactions with both ferrihydrite and goethite as iron reduction occurred. When carbon steel electrodes were exposed to S. putrefaciens, microbiologically influenced corrosion was demonstrated electrochemically and microscopically.

Destructive and non-destructive evaluation of cu/cu diffusion bonding with interlayer aluminum

NASA Astrophysics Data System (ADS)

Santosh Kumar, A.; Mohan, T.; Kumar, S. Suresh; Ravisankar, B.

2018-03-01

The current study is established an inspection procedure for assessing quality of diffusion bonded joints using destructive and non-destructive method. Diffusion bonding of commercially pure copper with aluminium interlayer was carried out uniaxial load at 15MPa for different temperatures under holding time 60 min in vacuum atmosphere. The bond qualities were determined by destructive and non-destructive testing method (ultrasonic C- scan). The bond interface and bonded samples were analysed using optical and scanning electron microscopy (SEM). The element composition of the fractured and bonded area is determined using the Energy Dispersive Spectrometry (EDS). The bond quality obtained by both testing methods and its parameters are correlated. The optimized bonding parameter for best bonding characteristics for copper diffusion bonding with aluminum interlayer is reported.

Ultrastructure and molecular phylogenetic position of a novel phagotrophic stramenopile from low oxygen environments: Rictus lutensis gen. et sp. nov. (Bicosoecida, incertae sedis).

PubMed

Yubuki, Naoji; Leander, Brian S; Silberman, Jeffrey D

2010-04-01

A novel free free-living phagotrophic flagellate, Rictus lutensis gen. et sp. nov., with two heterodynamic flagella, a permanent cytostome and a cytopharynx was isolated from muddy, low oxygen coastal sediments in Cape Cod, MA, USA. We cultivated and characterized this flagellate with transmission electron microscopy, scanning electron microscopy and molecular phylogenetic analyses inferred from small subunit (SSU) rDNA sequences. These data demonstrated that this organism has the key ultrastructural characters of the Bicosoecida, including similar transitional zones and a similar overall flagellar apparatus consisting of an x fiber and an L-shape microtubular root 2 involved in food capture. Although the molecular phylogenetic analyses were concordant with the ultrastructural data in placing R. lutensis with the bicosoecid clade, the internal position of this relatively divergent sequence within the clade was not resolved. Therefore, we interpret R. lutensis gen. et sp. nov. as a novel bicosoecid incertae sedis. Copyright 2009 Elsevier GmbH. All rights reserved.

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.

CdO-NPs; synthesis from 1D new nano Cd coordination polymer, characterization and application as anti-cancer drug for reducing the viability of cancer cells

NASA Astrophysics Data System (ADS)

Afzalian Mend, Behnaz; Delavar, Mahmoud; Darroudi, Majid

2017-04-01

The hexagonal CdO nano-particles (CdO-NPs) was prepared using new nano Cd coordination polymer, [Cd(NO3)(bipy)(pzca)]n (1) as a precursor, through direct calcination process at 500 °C. The precursor (1) was synthesized by sonochemical method. The new nano compound (1) was characterized by IR spectroscopy, elemental analyses, X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and thermal gravimetric analyses. The structure of nano coordination polymer was determined by comparing the XRD pattern of nano and single-crystal of compound (1). The nano CdO was characterized by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). In addition, the activity and efficiency of nano CdO as an anti-cancer drug was studied on cancer cells with different concentration. The results shows that the viability of cancer cells reduced above 2 μg/mL of CdO-NPs concentration.

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.

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.

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…

1-D Compression Behaviour of Acid Sulphate Soils Treated with Alkali-Activated Slag

PubMed Central

Islam, Shahidul; Haque, Asadul; Bui, Ha Hong

2016-01-01

Improvements of soft soils by mechanically mixing cementitious additives have been widely practised for construction of infrastructure. Mixing of additives improves strength and compressibility properties of soils through the development of soil structure. This study investigates the 1-D compression behaviour of alkali-activated slag treated acid sulphate soils (ASS) cured up to 365 days. The void ratio-logarithm of pressure (e-logσ′) behaviour of treated ASS, including the destructuration behaviour, with additive contents and curing time have been analysed. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses have been undertaken to explain the observed variations of the 1-D compression behaviour. This paper presents the results of these analyses in view of obtaining an insight into the 1-D compression behaviour of treated ASS with the help of mineralogical analysis. PMID:28773415

1-D Compression Behaviour of Acid Sulphate Soils Treated with Alkali-Activated Slag.

PubMed

Islam, Shahidul; Haque, Asadul; Bui, Ha Hong

2016-04-15

Improvements of soft soils by mechanically mixing cementitious additives have been widely practised for construction of infrastructure. Mixing of additives improves strength and compressibility properties of soils through the development of soil structure. This study investigates the 1-D compression behaviour of alkali-activated slag treated acid sulphate soils (ASS) cured up to 365 days. The void ratio-logarithm of pressure (e-logσ') behaviour of treated ASS, including the destructuration behaviour, with additive contents and curing time have been analysed. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses have been undertaken to explain the observed variations of the 1-D compression behaviour. This paper presents the results of these analyses in view of obtaining an insight into the 1-D compression behaviour of treated ASS with the help of mineralogical analysis.

Importance of microscopy in durability studies of solidified and stabilized contaminated soils

USGS Publications Warehouse

Klich, I.; Wilding, L.P.; Drees, L.R.; Landa, E.R.

1999-01-01

Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical, thermal, or biological means. Despite the increased use of S/S technologies, little research has been conducted on the weathering and degradation of solidified and stabilized wastes once the treated materials have been buried. Published data to verify the performance and durability of landfilled treated wastes over time are rare. In this preliminary study, optical and electron microscopy (scanning electron microscopy [SEM], transmission electron microscopy [TEM] and electron probe microanalyses [EPMA]) were used to evaluate weathering features associated with metal-bearing contaminated soil that had been solidified and stabilized with Portland cement and subsequently buried on site, stored outdoors aboveground, or achieved in a laboratory warehouse for up to 6 yr. Physical and chemical alteration processes identified include: freeze-thaw cracking, cracking caused by the formation of expansive minerals such as ettringite, carbonation, and the movement of metals from waste aggregates into the cement micromass. Although the extent of degradation after 6 yr is considered slight to moderate, results of this study show that the same environmental concerns that affect the durability of concrete must be considered when evaluating the durability and permanence of the solidification and stabilization of contaminated soils with cement. In addition, such evaluations cannot be based on leaching and chemical analyses alone. The use of all levels of microscopic analyses must be incorporated into studies of the long-term performance of S/S technologies.Solidification/stabilization (S/S) is recognized by the U.S. EPA as a best demonstrated available technology for the containment of contaminated soils and other hazardous wastes that cannot be destroyed by chemical, thermal, or biological means. Despite the increased use of S/S technologies, little research has been conducted on the weathering and degradation of solidified and stabilized wastes once the treated materials have been buried. Published data to verify the performance and durability of landfilled treated wastes over time are rare. In this preliminary study, optical and electron microscopy (scanning electron microscopy [SEM], transmission electron microscopy [TEM] and electron probe microanalyses [EPMA]) were used to evaluate weathering features associated with metal-bearing contaminated soil that had been solidified and stabilized with Portland cement and subsequently buried on site, stored outdoors aboveground, or archived in a laboratory, warehouse for up to 6 yr. Physical and chemical alteration processes identified include: freeze-thaw cracking, cracking caused by the formation of expansive minerals such as ettringite, carbonation, and the movement of metals from waste aggregates into the cement micromass. Although the extent of degradation after 6 yr is considered slight to moderate, results of this study show that the same environmental concerns that affect the durability of concrete must be considered when evaluating the durability and permanence of the solidification and stabilization of contaminated soils with cement. In addition, such evaluations cannot be based on leaching and chemical analyses alone. The use of all levels of microscopic analyses must be incorporated into studies of the long-term performance of S/S technologies.

TAKASAGO-6 apparatus for cryogenic coherent X-ray diffraction imaging of biological non-crystalline particles using X-ray free electron laser at SACLA

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

Kobayashi, Amane; Sekiguchi, Yuki; Oroguchi, Tomotaka

Coherent X-ray diffraction imaging (CXDI) is a technique for structure analyses of non-crystalline particles with dimensions ranging from micrometer to sub-micrometer. We have developed a diffraction apparatus named TAKASAGO-6 for use in single-shot CXDI experiments of frozen-hydrated non-crystalline biological particles at cryogenic temperature with X-ray free electron laser pulses provided at a repetition rate of 30 Hz from the SPring-8 Angstrom Compact free-electron LAser. Specimen particles are flash-cooled after being dispersed on thin membranes supported by specially designed disks. The apparatus is equipped with a high-speed translation stage with a cryogenic pot for raster-scanning of the disks at a speedmore » higher than 25 μm/33 ms. In addition, we use devices assisting the easy transfer of cooled specimens from liquid-nitrogen storages to the cryogenic pot. In the current experimental procedure, more than 20 000 diffraction patterns can be collected within 1 h. Here we report the key components and performance of the diffraction apparatus. Based on the efficiency of the diffraction data collection and the structure analyses of metal particles, biological cells, and cellular organelles, we discuss the future application of this diffraction apparatus for structure analyses of biological specimens.« less

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.

Characterization of the calcification of cardiac valve bioprostheses by environmental scanning electron microscopy and vibrational spectroscopy.

PubMed

Delogne, Christophe; Lawford, Patricia V; Habesch, Steven M; Carolan, Vikki A

2007-10-01

Bioprosthetic heart valve tissue and associated calcification were studied in their natural state, using environmental scanning electron microscopy (ESEM). Energy dispersive X-ray micro-analysis, X-ray diffraction, Fourier-transform infrared and Raman spectroscopy were used to characterize the various calcific deposits observed with ESEM. The major elements present in calcified valves were also analyzed by inductively coupled plasma-optical emission spectroscopy. To better understand the precursor formation of the calcific deposits, results from the elemental analyses were statistically correlated. ESEM revealed the presence of four broad types of calcium phosphate crystal morphology. In addition, two main patterns of organization of calcific deposits were observed associated with the collagen fibres. Energy dispersive X-ray micro-analysis identified the crystals observed by ESEM as salts containing mainly calcium and phosphate with ratios from 1.340 (possibly octacalcium phosphate, which has a Ca/P ratio of 1.336) to 2.045 (possibly hydroxyapatite with incorporation of carbonate and metal ion contaminants, such as silicon and magnesium, in the crystal lattice). Raman and fourier-transform infrared spectroscopy also identified the presence of carbonate and the analyses showed spectral features very similar to a crystalline hydroxyapatite spectrum, also refuting the presence of precursor phases such as beta-tricalcium phosphate, octacalcium phosphate and dicalcium phosphate dihydrate. The results of this study raised the possibility of the presence of precursor phases associated with the early stages of calcification.

Evaluation of bone loss in antibacterial coated dental implants: An experimental study in dogs.

PubMed

Godoy-Gallardo, Maria; Manzanares-Céspedes, Maria Cristina; Sevilla, Pablo; Nart, José; Manzanares, Norberto; Manero, José M; Gil, Francisco Javier; Boyd, Steven K; Rodríguez, Daniel

2016-12-01

The aim of this study was to evaluate the in vivo effect of antibacterial modified dental implants in the first stages of peri-implantitis. Thirty dental implants were inserted in the mandibular premolar sites of 5 beagle dogs. Sites were randomly assigned to Ti (untreated implants, 10units), Ti_Ag (silver electrodeposition treatment, 10units), and Ti_TSP (silanization treatment, 10units). Coated implants were characterized by scanning electron microscopy, interferometry and X-ray photoelectron spectroscopy. Two months after implant insertion, experimental peri-implantitis was initiated by ligature placement. Ligatures were removed 2months later, and plaque formation was allowed for 2 additional months. Clinical and radiographic analyses were performed during the study. Implant-tissue samples were prepared for micro computed tomography, backscattered scanning electron microscopy, histomorphometric and histological analyses and ion release measurements. X-ray, SEM and histology images showed that vertical bone resorption in treated implants was lower than in the control group (P<0.05). This effect is likely due to the capacity of the treatments to reduce bacteria colonization on the implant surface. Histological analysis suggested an increase of peri-implant bone formation on silanized implants. However, the short post-ligature period was not enough to detect differences in clinical parameters among implant groups. Within the limits of this study, antibacterial surface treatments have a positive effect against bone resorption induced by peri-implantitis. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultrasound-assisted facile synthesis of a new tantalum(V) metal-organic framework nanostructure: Design, characterization, systematic study, and CO{sub 2} adsorption performance

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

Sargazi, Ghasem, E-mail: g.sargazi@gmail.com; Young Researchers Society, Shahid Bahonar University of Kerman, Kerman, Iran; Afzali, Daryoush, E-mail: daryoush_afzali@yahoo.com

2017-06-15

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 2{sup k-1} factorial design experiments, and the response surfacemore » 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 m{sup 2}/g. The results revealed that the synthesized products could be utilized in various applications such as a novel candidate for CO{sub 2} adsorption. - Graphical abstract: A facile route was used for fabrication of a new metal -organic framework based on tantalum nanostructures that have high surface area, considerable porosity, homogenous morphology, and small size distribution.« less

Automated Transmission-Mode Scanning Electron Microscopy (tSEM) for Large Volume Analysis at Nanoscale Resolution

PubMed Central

Kuwajima, Masaaki; Mendenhall, John M.; Lindsey, Laurence F.; Harris, Kristen M.

2013-01-01

Transmission-mode scanning electron microscopy (tSEM) on a field emission SEM platform was developed for efficient and cost-effective imaging of circuit-scale volumes from brain at nanoscale resolution. Image area was maximized while optimizing the resolution and dynamic range necessary for discriminating key subcellular structures, such as small axonal, dendritic and glial processes, synapses, smooth endoplasmic reticulum, vesicles, microtubules, polyribosomes, and endosomes which are critical for neuronal function. Individual image fields from the tSEM system were up to 4,295 µm2 (65.54 µm per side) at 2 nm pixel size, contrasting with image fields from a modern transmission electron microscope (TEM) system, which were only 66.59 µm2 (8.160 µm per side) at the same pixel size. The tSEM produced outstanding images and had reduced distortion and drift relative to TEM. Automated stage and scan control in tSEM easily provided unattended serial section imaging and montaging. Lens and scan properties on both TEM and SEM platforms revealed no significant nonlinear distortions within a central field of ∼100 µm2 and produced near-perfect image registration across serial sections using the computational elastic alignment tool in Fiji/TrakEM2 software, and reliable geometric measurements from RECONSTRUCT™ or Fiji/TrakEM2 software. Axial resolution limits the analysis of small structures contained within a section (∼45 nm). Since this new tSEM is non-destructive, objects within a section can be explored at finer axial resolution in TEM tomography with current methods. Future development of tSEM tomography promises thinner axial resolution producing nearly isotropic voxels and should provide within-section analyses of structures without changing platforms. Brain was the test system given our interest in synaptic connectivity and plasticity; however, the new tSEM system is readily applicable to other biological systems. PMID:23555711

Au functionalized ZnO rose-like hierarchical structures and their enhanced NO2 sensing performance

NASA Astrophysics Data System (ADS)

Shingange, K.; Swart, H. C.; Mhlongo, G. H.

2018-04-01

Herein, we present ZnO rose-like hierarchical nanostructures employed as support to Au nanoparticles to produce Au functionalized three dimensional (3D) ZnO hierarchical nanostructures (Au/ZnO) for NO2 detection using a microwave-assisted method. Comparative analysis of NO2 sensing performance between the pristine ZnO and Au/ZnO rose-like structures at 300 °C revealed improved NO2 response and rapid response-recovery times with Au incorporation owing to a combination of high surface accessibility induced by hierarchical nanostructure design and catalytic activity of the small Au nanoparticles. Structural and optical analyses acquired from X-ray diffraction, scanning electron microscopy, transmission electron microscope and photoluminescence spectroscopy were also performed.

Insights into the prominent effect of mahanimbine on Acanthamoeba castellanii: Cell profiling analysis based on microscopy techniques

NASA Astrophysics Data System (ADS)

Hashim, Fatimah; Amin, Nakisah Mat

2017-02-01

Mahanimbine (MH), has been shown to have antiamoeba properties. Therefore, the aim of this study was to assess the growth inhibitory mechanisms of MH on Acanthamoeba castellanii, a causative agents for Acanthamoeba keratitis. The IC50 value obtained for MH against A. castellanii was 1.18 µg/ml. Light and scanning electron microscopy observation showed that most cells were in cystic appearance. While transmission electron microscopy observation revealed changes at the ultrastructural level and fluorescence microscopy observation indicated the induction of apoptosis and autophagic activity in the amoeba cytoplasms. In conclusion, MH has very potent anti-amoebic properties on A. castellanii as is shown by cytotoxicity analyses based on microscopy techniques.

Micromorphology of trichomes of Thymus malyi (Lamiaceae).

PubMed

Marin, M; Koko, V; Duletić-Lausević, S; Marin, P D

2008-12-01

Micromorphological, ultrastructural and morphometric investigations of the trichomes of Thymus malyi were carried out using a light microscope, a scanning electron microscope and a transmission electron microscope. Unbranched non-glandular trichomes, peltate and capitate glandular trichomes were described. The leaves of Thymus malyi bear non-glandular and glandular trichomes on both sides. Estimates of the volume density (i.e. their volume fraction per unit volume) of non-glandular trichomes were higher as compared to volume density of peltate and capitate glandular trichomes. Estimates of the number of these trichomes per area on sections showed that the capitate trichomes were the most abundant. Ultrastructural analyses of cell inner structure have shown numerous mitochondria, big nuclei and plastids with lipid globules and starch grains.

Synthesis of noble metal/carbon nanotube composites in supercritical methanol.

PubMed

Sun, Zhenyu; Fu, Lei; Liu, Zhimin; Han, Buxing; Liu, Yunqi; Du, Jimin

2006-03-01

A simple and efficient route has been employed to deposit noble metal nanoparticles (Pt, Ru, Pt-Ru, Rh, Ru-Sn) onto carbon nanotubes (CNTs) in supercritical methanol solution. In this method, the inorganic metallic salts acted as metal precursors, and methanol as solvent as well as reductant for the precursors. The as-prepared nanocomposites were structurally and morphologically characterized by X-ray diffraction spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy, and X-ray photoelectron spectroscopy analyses. It was demonstrated that the CNTs were decorated by crystalline metal nanoparticles with uniform sizes and a narrow particle size distribution. The size and loading content of the nanoparticles on CNTs could be tuned by manipulating reaction parameters. Furthermore, the formation mechanism of the composites was also discussed.

Analysis of acute brain slices by electron microscopy: a correlative light-electron microscopy workflow based on Tokuyasu cryo-sectioning.

PubMed

Loussert Fonta, Celine; Leis, Andrew; Mathisen, Cliff; Bouvier, David S; Blanchard, Willy; Volterra, Andrea; Lich, Ben; Humbel, Bruno M

2015-01-01

Acute brain slices are slices of brain tissue that are kept vital in vitro for further recordings and analyses. This tool is of major importance in neurobiology and allows the study of brain cells such as microglia, astrocytes, neurons and their inter/intracellular communications via ion channels or transporters. In combination with light/fluorescence microscopies, acute brain slices enable the ex vivo analysis of specific cells or groups of cells inside the slice, e.g. astrocytes. To bridge ex vivo knowledge of a cell with its ultrastructure, we developed a correlative microscopy approach for acute brain slices. The workflow begins with sampling of the tissue and precise trimming of a region of interest, which contains GFP-tagged astrocytes that can be visualised by fluorescence microscopy of ultrathin sections. The astrocytes and their surroundings are then analysed by high resolution scanning transmission electron microscopy (STEM). An important aspect of this workflow is the modification of a commercial cryo-ultramicrotome to observe the fluorescent GFP signal during the trimming process. It ensured that sections contained at least one GFP astrocyte. After cryo-sectioning, a map of the GFP-expressing astrocytes is established and transferred to correlation software installed on a focused ion beam scanning electron microscope equipped with a STEM detector. Next, the areas displaying fluorescence are selected for high resolution STEM imaging. An overview area (e.g. a whole mesh of the grid) is imaged with an automated tiling and stitching process. In the final stitched image, the local organisation of the brain tissue can be surveyed or areas of interest can be magnified to observe fine details, e.g. vesicles or gold labels on specific proteins. The robustness of this workflow is contingent on the quality of sample preparation, based on Tokuyasu's protocol. This method results in a reasonable compromise between preservation of morphology and maintenance of antigenicity. Finally, an important feature of this approach is that the fluorescence of the GFP signal is preserved throughout the entire preparation process until the last step before electron microscopy. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

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.

Characterizing mineral dusts and other aerosols from the Middle East--Part 1: ambient sampling.

PubMed

Engelbrecht, Johann P; McDonald, Eric V; Gillies, John A; Jayanty, R K M; Casuccio, Gary; Gertler, Alan W

2009-02-01

The purpose of the Enhanced Particulate Matter Surveillance Program was to provide scientifically founded information on the chemical and physical properties of dust collected over a period of approximately 1 year in Djibouti, Afghanistan (Bagram, Khowst), Qatar, United Arab Emirates, Iraq (Balad, Baghdad, Tallil, Tikrit, Taji, Al Asad), and Kuwait (northern, central, coastal, and southern regions). Three collocated low-volume particulate samplers, one each for the total suspended particulate matter, < 10 micro m in aerodynamic diameter (PM(10)) particulate matter, and < 2.5 micro m in aerodynamic diameter (PM(2.5)) particulate matter, were deployed at each of the 15 sites, operating on a '1 in 6' day sampling schedule. Trace-element analysis was performed to measure levels of potentially harmful metals, while major-element and ion-chemistry analyses provided an estimate of mineral components. Scanning electron microscopy with energy dispersive spectroscopy was used to analyze the chemical composition of small individual particles. Secondary electron images provided information on particle size and shape. This study shows the three main air pollutant types to be geological dust, smoke from burn pits, and heavy metal condensates (possibly from metals smelting and battery manufacturing facilities). Non-dust storm events resulted in elevated trace metal concentrations in Baghdad, Balad, and Taji in Iraq. Scanning-electron-microscopy secondary electron images of individual particles revealed no evidence of freshly fractured quartz grains. In all instances, quartz grains had rounded edges and mineral grains were generally coated by clay minerals and iron oxides.

Facile synthesis of ZnPc nanocubes: An electron emitting material for field emission display devices

NASA Astrophysics Data System (ADS)

Samanta, M.; Ghorai, U. K.; Mukherjee, M.; Howli, P.; Chattopadhyay, K. K.

2017-05-01

A simple low temperature water chemical route for synthesizing Zinc Phthalocyanine (ZnPc) nanostructures were reported here. The as-prepared samples were well analysed by X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) technique. The plausible formation mechanism of cube like nanostructures was also explained here. Cold cathode emission properties of ZnPc nanocubes were studied by using an indigenously designed high vacuum system at anode to cathode distance 130 µm. The turn on field and enhancement factor is found to be 5.0 V/μm @ 1µA/cm2 and 1757 respectively. Cold cathode emission properties were further investigated theoretically by finite element method using ANSYS Maxwell simulation package. The obtained results strongly professed that ZnPc nanocubes can act as potential candidate for electron emitter for field emission display devices and many more.

Synthesis and characterization of nanocrystalline Co-Fe-Nb-Ta-B alloy

NASA Astrophysics Data System (ADS)

Raanaei, Hossein; Fakhraee, Morteza

2017-09-01

In this research work, structural and magnetic evolution of Co57Fe13Nb8Ta4B18 alloy, during mechanical alloying process, have been investigated by using, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electron dispersive X-ray spectroscopy, differential thermal analysis and also vibrating sample magnetometer. It is observed that at 120 milling time, the crystallite size reaches to about 7.8 nm. Structural analyses show that, the solid solution of the initial powder mixture occurs at160 h milling time. The coercivity behavior demonstrates a rise, up to 70 h followed by decreasing tendency up to final stage of milling process. Thermal analysis of 160 h milling time sample reveals two endothermic peaks. The characterization of annealed milled sample for 160 h milling time at 427 °C shows crystallite size growth accompanied by increasing in saturation magnetization.

Effects of lead pollution on Ammonia parkinsoniana (foraminifera): ultrastructural and microanalytical approaches.

PubMed

Frontalini, F; Curzi, D; Giordano, F M; Bernhard, J M; Falcieri, E; Coccioni, R

2015-01-30

The responses of Ammonia parkinsoniana (Foraminifera) exposed to different concentrations of lead (Pb) were evaluated at the cytological level. Foraminifera-bearing sediments were placed in mesocosms that were housed in aquaria each with seawater of a different lead concentration. On the basis of transmission electron microscopy and environmental scanning electron microscopy coupled with energy dispersive spectrometer analyses, it was possible to recognize numerous morphological differences between untreated (i.e., control) and treated (i.e., lead enrichment) specimens. In particular, higher concentrations of this pollutant led to numerical increase of lipid droplets characterized by a more electron-dense core, proliferation of residual bodies, a thickening of the organic lining, mitochondrial degeneration, autophagosome proliferation and the development of inorganic aggregates.  All these cytological modifications might be related to the pollutant-induced stress and some of them such as the thickening of organic lining might suggest a potential mechanism of protection adopted by foraminifera.

Modulation of electrical potential and conductivity in an atomic-layer semiconductor heterojunction

PubMed Central

Kobayashi, Yu; Yoshida, Shoji; Sakurada, Ryuji; Takashima, Kengo; Yamamoto, Takahiro; Saito, Tetsuki; Konabe, Satoru; Taniguchi, Takashi; Watanabe, Kenji; Maniwa, Yutaka; Takeuchi, Osamu; Shigekawa, Hidemi; Miyata, Yasumitsu

2016-01-01

Semiconductor heterojunction interfaces have been an important topic, both in modern solid state physics and in electronics and optoelectronics applications. Recently, the heterojunctions of atomically-thin transition metal dichalcogenides (TMDCs) are expected to realize one-dimensional (1D) electronic systems at their heterointerfaces due to their tunable electronic properties. Herein, we report unique conductivity enhancement and electrical potential modulation of heterojunction interfaces based on TMDC bilayers consisted of MoS2 and WS2. Scanning tunneling microscopy/spectroscopy analyses showed the formation of 1D confining potential (potential barrier) in the valence (conduction) band, as well as bandgap narrowing around the heterointerface. The modulation of electronic properties were also probed as the increase of current in conducting atomic force microscopy. Notably, the observed band bending can be explained by the presence of 1D fixed charges around the heterointerface. The present findings indicate that the atomic layer heterojunctions provide a novel approach to realizing tunable 1D electrical potential for embedded quantum wires and ultrashort barriers of electrical transport. PMID:27515115

Facile synthesis of Co3O4 hexagonal plates by flux method

NASA Astrophysics Data System (ADS)

Han, Ji-Long; Meng, Qing-Fen; Gao, Sheng-Li

2018-01-01

Using a novel flux method, a hexagonal plate of Co3O4 was directly synthesized. In this method, CoCl2·6H2O, NaOH, and the cosolvent H3BO3 were heated to 750 °C for 2 h in a corundum crucible. The products were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and high-resolution transmission electron microscope (HRTEM). Furthermore, XRD studies indicated that the product consisted of a cubic phase of Co3O4, and the phase existed in a completely crystalline form. Then, SEM results indicated that these hexagonal plates tiered up and they had diameters in the range of 2-10 μm. According to the results of SAED and HRTEM analyses, the interlayer spacing was about 0.24 nm, which corresponds to the interlayer distance of (3 1 1) crystal plane of cubic Co3O4.

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

A reconnaissance for signs of a Mississippi Valley-type lead-zinc mineralizing system on the eastern flank of the Rutbah Uplift, Anbar Province, Iraq

USGS Publications Warehouse

Hayes, Timothy S.; Mustafa, Mazin; Bennet, Thair

2014-01-01

Reconnaissance field visits and rock sampling were conducted at eight geologically selected locations within Mesozoic rocks on the eastern flank of the Rutbah Uplift, Anbar Province, western Iraq, in an attempt to determine if these rocks have been affected by a Mississippi Valley-Type (MVT) lead-zinc mineralizing system. Samples subsequently were studied by carbonate mineral staining, transmitted and reflected light petrology, and scanning electron microscopy with semi-quantitative energy dispersive elemental analyses. Single samples were studied by each, inductively coupled plasma mass spectrometry analyses of trace elements and fluid inclusion microthermometry. Permissive evidence indicates that there has been a MVT system present, but none of the evidence is considered definitive.

Solidification and Microstructure of Ni-Containing Al-Si-Cu Alloy

NASA Astrophysics Data System (ADS)

Fang, Li; Ren, Luyang; Geng, Xinyu; Hu, Henry; Nie, Xueyuan; Tjong, Jimi

2018-01-01

2 wt. % nickel (Ni) addition was introduced into a conventional cast aluminum alloy A380. The influence of transition alloying element nickel on the solidification behavior of cast aluminum alloy A380 was investigated via thermal analyses based on temperature measurements recorded on cooling curves. The corresponding first and second derivatives of the cooling curves were derived to reveal the details of phase changes during solidification. The nucleation of the primary α-Al phase and eutectic phases were analyzed. The microstructure analyses by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) indicate that different types and amount of eutectic phases are present in the tested two alloys. The introduction of Ni forms the complex Ni-containing intermetallic phases with Cu and Al.

Microstructural characterization and simulation of damage for geared sheet components

NASA Astrophysics Data System (ADS)

Gerstein, G.; Isik, K.; Gutknecht, F.; Sieczkarek, P.; Ewert, J.; Tekkaya, A. E.; Clausmeyer, T.; Nürnberger, F.

2017-09-01

The evolution of damage in geared components manufactured from steel sheets was investigated, to analyse the influence of damage caused by the sheet-bulk-metal forming. Due to the inhomogeneous and multi-axial deformation in the investigated parts, different aspects such as the location-dependent shape and size of voids are analysed by means of various microscopic methods. In particular, a method to characterize the state of damage evolution, i. e. void nucleation, growth and coalescence using scanning electron microscopy (SEM) is applied. The investigations reveal a strong dependence of the void area fraction, shape of voids and thus damage evolution on the loading mode. The microstructural analysis is complemented with FEM simulations using material models which consider the characteristics of the void evolution.

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.

Development of Scanning Ultrafast Electron Microscope Capability.

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

Collins, Kimberlee Chiyoko; Talin, Albert Alec; Chandler, David W.

Modern semiconductor devices rely on the transport of minority charge carriers. Direct examination of minority carrier lifetimes in real devices with nanometer-scale features requires a measurement method with simultaneously high spatial and temporal resolutions. Achieving nanometer spatial resolutions at sub-nanosecond temporal resolution is possible with pump-probe methods that utilize electrons as probes. Recently, a stroboscopic scanning electron microscope was developed at Caltech, and used to study carrier transport across a Si p-n junction [ 1 , 2 , 3 ] . In this report, we detail our development of a prototype scanning ultrafast electron microscope system at Sandia National Laboratoriesmore » based on the original Caltech design. This effort represents Sandia's first exploration into ultrafast electron microscopy.« less

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

Unique isothermal crystallization behavior of novel polyphenylene sulfide/inorganic fullerene-like WS2 nanocomposites.

PubMed

Naffakh, Mohammed; Marco, Carlos; Gómez, Marián A; Jiménez, Ignacio

2008-11-27

The isothermal crystallization of polyphenylene sulfide (PPS) nanocomposites with inorganic fullerene-like tungsten disulfide nanoparticles (IF-WS2) has been studied from a thermal and morphological point of view, using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), polarized optical microscopy (POM) and time-resolved synchrotron X-ray diffraction. All the analyses revealed that the incorporation of the IF-WS2 altered significantly the crystallization behavior of PPS, in a way strongly dependent with the nanocomposite composition. The addition of IF-WS2 in 0.1 wt % proportion retarded the crystallization of PPS by increasing its fold surface free energy in a 10%. However, addition of the nanoparticles in excess of 1 wt % results in a promotion of the crystallization rate with reduction of the fold surface free energy to half the value of pure PPS.

Micromorphological characterization of adhesive interface of sound dentin and total-etch and self-etch adhesives.

PubMed

Drobac, Milan; Stojanac, Igor; Ramić, Bojana; Premović, Milica; Petrović, Ljubomir

2015-01-01

The ultimate goal in restorative dentistry has always been to achieve strong and permanent bond between the dental tissues and filling materials. It is not easy to achieve this task because the bonding process is different for enamel and dentin-dentin is more humid and more organic than enamel. It is moisture and organic nature of dentin that make this hard tissue very complex to achieve adhesive bond. One of the first and most widely used tools for examining the adhesive bond between hard dental tissues and composite restorative materials is scanning electron microscopy. The aim of this study was scanning electron microscopy analyzes the interfacial micro morphology of total-etch and self-etch adhesives. Micro morphological characteristics of interface between total-etch adhesive (Prime & Bond NT) in combination with the corresponding composite (Ceram X Mono) were compared with those of self-etching adhesive (AdheSE One) in, combination with the corresponding composite (Tetric EvoCeram). The specimens were observed under 1000 x magnification of scanning electron microscopy (JEOL, JSM-6460 Low Vacuum). Measurement of the thickness of the hybrid layer of the examined com posite systems was performed with the software of the device used (NIH Image Analyser). Micromorphological analysis of interface showed that the hybrid layer in sound dentin was well formed, its average thickness being 2.68 microm, with a large number of resin tags and a large amount of lateral branches for specimens with a composite system Prime & Bond NT-Ceram X Mono. However, the specimens' with composite systems Adhese One-Tetric EvoCeram did not show the presence of hybrid layer and the resin tags were poorly represented. The results of this study suggest that total-etch adhesives bond better with sound dentin than self-etch adhesive.

Comparative evaluation of topographical data of dental implant surfaces applying optical interferometry and scanning electron microscopy.

PubMed

Kournetas, N; Spintzyk, S; Schweizer, E; Sawada, T; Said, F; Schmid, P; Geis-Gerstorfer, J; Eliades, G; Rupp, F

2017-08-01

Comparability of topographical data of implant surfaces in literature is low and their clinical relevance often equivocal. The aim of this study was to investigate the ability of scanning electron microscopy and optical interferometry to assess statistically similar 3-dimensional roughness parameter results and to evaluate these data based on predefined criteria regarded relevant for a favorable biological response. Four different commercial dental screw-type implants (NanoTite Certain Prevail, TiUnite Brånemark Mk III, XiVE S Plus and SLA Standard Plus) were analyzed by stereo scanning electron microscopy and white light interferometry. Surface height, spatial and hybrid roughness parameters (Sa, Sz, Ssk, Sku, Sal, Str, Sdr) were assessed from raw and filtered data (Gaussian 50μm and 5μm cut-off-filters), respectively. Data were statistically compared by one-way ANOVA and Tukey-Kramer post-hoc test. For a clinically relevant interpretation, a categorizing evaluation approach was used based on predefined threshold criteria for each roughness parameter. The two methods exhibited predominantly statistical differences. Dependent on roughness parameters and filter settings, both methods showed variations in rankings of the implant surfaces and differed in their ability to discriminate the different topographies. Overall, the analyses revealed scale-dependent roughness data. Compared to the pure statistical approach, the categorizing evaluation resulted in much more similarities between the two methods. This study suggests to reconsider current approaches for the topographical evaluation of implant surfaces and to further seek after proper experimental settings. Furthermore, the specific role of different roughness parameters for the bioresponse has to be studied in detail in order to better define clinically relevant, scale-dependent and parameter-specific thresholds and ranges. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Characterization of TiN, TiC and Ti(C,N) in titanium-alloyed ferritic chromium steels focusing on the significance of different particle morphologies

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

Michelic, S.K., E-mail: susanne.michelic@unileoben.ac.at; Loder, D.; Reip, T.

2015-02-15

Titanium-alloyed ferritic chromium steels are a competitive option to classical austenitic stainless steels owing to their similar corrosion resistance. The addition of titanium significantly influences their final steel cleanliness. The present contribution focuses on the detailed metallographic characterization of titanium nitrides, titanium carbides and titanium carbonitrides with regard to their size, morphology and composition. The methods used are manual and automated Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy as well as optical microscopy. Additional thermodynamic calculations are performed to explain the precipitation procedure of the analyzed titanium nitrides. The analyses showed that homogeneous nucleation is decisive at an earlymore » process stage after the addition of titanium. Heterogeneous nucleation gets crucial with ongoing process time and essentially influences the final inclusion size of titanium nitrides. A detailed investigation of the nuclei for heterogeneous nucleation with automated Scanning Electron Microscopy proved to be difficult due to their small size. Manual Scanning Electron Microscopy and optical microscopy have to be applied. Furthermore, it was found that during solidification an additional layer around an existing titanium nitride can be formed which changes the final inclusion morphology significantly. These layers are also characterized in detail. Based on these different inclusion morphologies, in combination with thermodynamic results, tendencies regarding the formation and modification time of titanium containing inclusions in ferritic chromium steels are derived. - Graphical abstract: Display Omitted - Highlights: • The formation and modification of TiN in the steel 1.4520 was examined. • Heterogeneous nucleation essentially influences the final steel cleanliness. • In most cases heterogeneous nuclei in TiN inclusions are magnesium based. • Particle morphology provides important information on inclusion formation.« less

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...

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

Stöber, Laura, E-mail: laura.stoeber@tuwien.ac.at; Patocka, Florian, E-mail: florian.patocka@tuwien.ac.at; Schneider, Michael, E-mail: michael.schneider@tuwien.ac.at

In this paper, the authors report on the high temperature performance of sputter deposited molybdenum (Mo) and molybdenum nitride (Mo{sub 2}N) thin films. Various argon and nitrogen gas compositions are applied for thin film synthetization, and the amount of nitrogen incorporation is determined by Auger measurements. Furthermore, effusion measurements identifying the binding conditions of the nitrogen in the thin film are performed up to 1000 °C. These results are in excellent agreement with film stress and scanning electron microscope analyses, both indicating stable film properties up to annealing temperatures of 500 °C.

Advanced STEM microanalysis of bimetallic nanoparticle catalysts

NASA Astrophysics Data System (ADS)

Lyman, Charles E.; Dimick, Paul S.

2012-05-01

Individual particles within bimetallic nanoparticle populations are not always identical, limiting the usefulness of bulk analysis techniques such as EXAFS. The scanning transmission electron microscope (STEM) is the only instrument able to characterize supported nanoparticle populations on a particle-by-particle basis. Quantitative elemental analyses of sub-5-nm particles reveal phase separations among particles and surface segregation within particles. This knowledge can lead to improvements in bimetallic catalysts. Advanced STEMs with field-emission guns, aberration-corrected optics, and efficient signal detection systems allow analysis of sub-nanometer particles.

Rheological Analysis of Live and Dead Microalgae Suspensions

NASA Astrophysics Data System (ADS)

Song, Young Seok; Kang, Chul; Jeong, Jiwon; Kim, Kyu-Oh; Lim, Eunju

2018-04-01

We investigate the rheological properties of microalgae suspensions that are currently being used in various applications. Two kinds of microalgae, chlorella and Synechococcus, were used for preparation of the suspensions, and their rheological characteristics were analyzed experimentally. In order to evaluate the viability of algae, we performed live and dead tests using trypan blue staining assays. Morphological analyses for the algae were conducted using a scanning electron microscope (SEM) and an optical microscope (OP). We examined the viscoelastic behavior of the live and the dead algae suspensions by performing dynamic oscillatory shear tests.

Hair waving natural product: Dillenia indica seed sap.

PubMed

Saikia, Jyoti Prasad

2013-02-01

Knowing keratin is the main component and mechanical strength of hair a study was performed to evaluate whether Dillenia indica seed sap can affect molecular strength of hair or not. In the present study the human hair collected from barber shop waste were subjected to purified sap for 12 h and then analysed using Fourier transform infrared spectroscopy (FTIR) for documenting evidence for keratin degradation. Further the deterioration was confirmed by thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). Copyright © 2012 Elsevier B.V. All rights reserved.

A New Technique for Preserving the Form of Artificially Inflated Endophalli of Bees.

PubMed

Dutra, A L; Oliveira, R

2017-04-01

We present a simple technique for keeping the form of artificially expanded endophalli in bees (Hymenoptera). Endophalli were inflated using the introduction of low melting-point agarose from a syringe inserted in the anterior opening of the metasoma. Under refrigeration, the endophalli kept their expanded shape for up to three days allowing the description of structure, morphometric analyses, and examination of the external sculpturing of the cuticle under scanning electron microscope. The technique provides new possibilities for the study of functional morphology, sexual selection, and reconstruction of bee phylogeny.

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

Production of intensive negative lithium beam with caesium sputter-type ion source

NASA Astrophysics Data System (ADS)

Lobanov, Nikolai R.

2018-01-01

Compounds of lithium oxide, hydroxide and carbonate, mixed with silver, were prepared for use as a cathode in caesium-sputter ion source. The intention was to determine the procedure which would produce the highest intensity negative lithium beams over extended period and with maximum stability. The chemical composition and properties of the samples were analysed using mass-spectrometry, optical microscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analyses (EDX) and Raman spectroscopy. These analyses showed that the chemical transformations with components resulted from pressing, storage and bake out were qualitatively in agreement with expectations. Intensive negative lithium ion beams >1 μA were delivered using cathodes fabricated from materials with multicomponent chemical composition when the following conditions were met: (i) use of components with moderate enthalpy of formation; (ii) low moisture content at final stage of cathode production and (iii) small concentration of water molecules in hydrate phase in the cathode mixture.

Characterization of blue decorated Renaissance pottery fragments from Caltagirone (Sicily, Italy)

NASA Astrophysics Data System (ADS)

Barilaro, D.; Crupi, V.; Interdonato, S.; Majolino, D.; Venuti, V.; Barone, G.; La Russa, M. F.; Bardelli, F.

2008-07-01

Renaissance blue decorated pottery fragments from the archaeological site of Caltagirone (Sicily, Italy) were analysed by scanning electron microscopy - energy dispersive X-ray spectrometry (SEM/EDS). The samples were dated back to 16th century AD on the basis of archaeological observations. The micro-chemical analyses were performed on the ceramic body and the surface decorated layer of the samples. Particularly, the investigation was addressed the characterization of the coating blue decorations. The obtained results allowed us to clearly identify smalt as pigment. Also the presence of arsenic (As) was revealed and the Co/As ratio values were calculated and related to the different process used for the pigment preparation. Further spectroscopic analyses, performed through X-ray absorbance spectroscopy (XAS), carried out at the Co K-edge, confirmed the micro-analytical results and permitted us to identify the oxidation form and the local environment of cobalt atoms.

Assessment of biofilm changes and concentration-depth profiles during arsenopyrite oxidation by Acidithiobacillus thiooxidans.

PubMed

Ramírez-Aldaba, Hugo; Vazquez-Arenas, Jorge; Sosa-Rodríguez, Fabiola S; Valdez-Pérez, Donato; Ruiz-Baca, Estela; García-Meza, Jessica Viridiana; Trejo-Córdova, Gabriel; Lara, René H

2017-08-01

Biofilm formation and evolution are key factors to consider to better understand the kinetics of arsenopyrite biooxidation. Chemical and surface analyses were carried out using Raman spectroscopy, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), glow discharge spectroscopy (GDS), and protein analysis (i.e., quantification) in order to evaluate the formation of intermediate secondary compounds and any significant changes arising in the biofilm structure of Acidithiobacillus thiooxidans during a 120-h period of biooxidation. Results show that the biofilm first evolves from a low cell density structure (1 to 12 h) into a formation of microcolonies (24 to 120 h) and then finally becomes enclosed by a secondary compound matrix that includes pyrite (FeS 2 )-like, S n 2- /S 0 , and As 2 S 3 compounds, as shown by Raman and SEM-EDS. GDS analyses (concentration-depth profiles, i.e., 12 h) indicate significant differences for depth speciation between abiotic control and biooxidized surfaces, thus providing a quantitative assessment of surface-bulk changes across samples (i.e. reactivity and /or structure-activity relationship). Respectively, quantitative protein analyses and CLSM analyses suggest variations in the type of extracellular protein expressed and changes in the biofilm structure from hydrophilic (i.e., exopolysaccharides) to hydrophobic (i.e., lipids) due to arsenopyrite and cell interactions during the 120-h period of biooxidation. We suggest feasible environmental and industrial implications for arsenopyrite biooxidation based on the findings of this study.

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.

Ultrastructure of selected struvite-containing urinary calculi from dogs.

PubMed

Domingo-Neumann, R A; Ruby, A L; Ling, G V; Schiffman, P S; Johnson, D L

1996-09-01

To elucidate the ultrastructural details of struvite-containing urinary calculi from dogs. 38 specimens were selected from a collection of approximately 13,000 canine urinary calculi: 18 of these were composed entirely of struvite, and 20 consisted of struvite and calcium phosphate (apatite). Qualitative and quantitative analyses of specimens included use of plain and polarized light microscopy, x-ray diffractometry, scanning electron microscopy with backscattered electron imagery, x-ray fluorescence scans, and electron microprobe analysis. 4 textural types were recognized among struvite calculi, and 4 textural types of struvite-apatite calculi were described. Evidences of calculus dissolution were described from 4 calculi studied. The presence of small, well interconnected primary pores in struvite-containing urinary calculi from dogs appears to be a significant factor in determining the possible interaction of calculi with changes in the urine composition. The progress of dissolution from the calculus surface to the calculus interior appears to be largely affected by the primary porosity originally present between crystals forming the calculus framework. Apatite was observed to be more resistant to dissolution than struvite. The prevalence of fine concentric laminations having low porosity, and the common occurrence of apatite among struvite-containing urinary calculi from dogs may be 2 reasons why the efficacy of dietary and medicinal manipulations in dissolving urinary calculi is greater among cats than it is among dogs.

Effect of SiO2, PVA and glycerol concentrations on chemical and mechanical properties of alginate-based films.

PubMed

Yang, Manli; Shi, Jinsheng; Xia, Yanzhi

2018-02-01

Sodium alginate (SA)/polyvinyl alcohol (PVA)/SiO 2 nanocomposite films were prepared by in situ polymerization through solution casting and solvent evaporation. The effect of different SA/PVA ratios, SiO 2 , and glycerol content on the mechanical properties, water content, water solubility, and water vapor permeability were studied. The nanocomposite films were characterized by Fourier transform infrared, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and thermal stability (thermogravimetric analysis/differential thermogravimetry) analyses. The nanocomposites showed the highest values of mechanical properties, such as SA/PVA ratio, SiO 2 , and glycerol content was 7:3, 6wt.%, and 0.25g/g SA, respectively. The tensile strength and elongation at break (E%) of the nanocomposites increased by 525.7% and 90.7%, respectively, compared with those of the pure alginate film. The Fourier transform infrared spectra showed a new SiOC band formed in the SA/PVA/SiO 2 nanocomposite film. The scanning electron microscopy image revealed good adhesion between SiO 2 and SA/PVA matrix. After the incorporation of PVA and SiO 2 , the water resistance of the SA/PVA/SiO 2 nanocomposite film was markedly improved. Transparency decreased with increasing PVA content but was enhanced by adding SiO 2 . Copyright © 2017. Published by Elsevier B.V.

Quantitative Electron-Excited X-Ray Microanalysis of Borides, Carbides, Nitrides, Oxides, and Fluorides with Scanning Electron Microscopy/Silicon Drift Detector Energy-Dispersive Spectrometry (SEM/SDD-EDS) and NIST DTSA-II.

PubMed

Newbury, Dale E; Ritchie, Nicholas W M

2015-10-01

A scanning electron microscope with a silicon drift detector energy-dispersive X-ray spectrometer (SEM/SDD-EDS) was used to analyze materials containing the low atomic number elements B, C, N, O, and F achieving a high degree of accuracy. Nearly all results fell well within an uncertainty envelope of ±5% relative (where relative uncertainty (%)=[(measured-ideal)/ideal]×100%). Quantification was performed with the standards-based "k-ratio" method with matrix corrections calculated based on the Pouchou and Pichoir expression for the ionization depth distribution function, as implemented in the NIST DTSA-II EDS software platform. The analytical strategy that was followed involved collection of high count (>2.5 million counts from 100 eV to the incident beam energy) spectra measured with a conservative input count rate that restricted the deadtime to ~10% to minimize coincidence effects. Standards employed included pure elements and simple compounds. A 10 keV beam was employed to excite the K- and L-shell X-rays of intermediate and high atomic number elements with excitation energies above 3 keV, e.g., the Fe K-family, while a 5 keV beam was used for analyses of elements with excitation energies below 3 keV, e.g., the Mo L-family.

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.

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.

Hyaline cartilage surface study with an environmental scanning electron microscope. An experimental study.

PubMed

Sastre, S; Suso, S; Segur, J M; Bori, G; Carbonell, J A; Agustí, E; Nuñez, M

2009-11-01

To obtain images of the articular surface of fresh osteochondral grafts using an environmental scanning electron microscope (ESEM). To evaluate and compare the main morphological aspects of the chondral surface of the fresh grafts. To develop a validated classification system on the basis of the images obtained via the ESEM. The study was based on osteochondral fragments from the internal condyle of the knee joint of New Zealand rabbits, corresponding to fresh chondral surface. One hundred images were obtained via the ESEM and these were classified by two observers according to a category system. The Kappa index and the corresponding confidence interval (CI) were calculated. Of the samples analysed, 62-72% had an even surface. Among the samples with an uneven surface 17-22% had a hillocky appearance and 12-16% a knobbly appearance. As regards splits, these were not observed in 92-95% of the surfaces; 4-7% showed superficial splits and only 1% deep splits. In 78-82% of cases no lacunae in the surface were observed, while 17-20% showed filled lacunae and only 1-2% presented empty lacunae. The study demonstrates that the ESEM is useful for obtaining and classifying images of osteochondral grafts.

Production of a cellulase-free alkaline xylanase from Bacillus pumilus MTCC 5015 by submerged fermentation and its application in biobleaching.

PubMed

Thomas, Leya; Sindhu, Raveendran; Binod, Parameswaran; Pandey, Ashok

2015-06-01

Here, we described the production of a cellulase-free alkaline xylanase from Bacillus pumilus MTCC 5015 by submerged fermentation and its application in biobleaching. Various process parameters affecting xylanase production by B. pumilus were optimized by adopting a Plackett-Burman design (PBD) as well as Response surface methodology (RSM). These statistical methods aid in improving the enzyme yield by analysing the individual crucial components of the medium. Maximum production was obtained with 4% yeast extract, 0.08% magnesium sulphate, 30 h of inoculum age, incubation temperature of 33.5 degrees C and pH 9.0. Under optimized conditions, the xylanase activity was 372 IU/ml. Media engineering improved a 5-fold increase in the enzyme production. Scanning electron microscopy (SEM) showed significant changes on the surface of xylanase treated pulps as a result of xylan hydrolysis. Increased roughness of paper carton fibres was apparent in scanning electron micrograph due to opening of the micro fibrils present on the surface by xylanase action. The untreated pulp did not show any such change. These results demonstrated that the B. pumilus MTCC 5015 xylanase was effective in bio-bleaching of paper carton.

Wildfires in the Triassic of Gondwana Paraná Basin

NASA Astrophysics Data System (ADS)

Cardoso, Daiane dos Santos; Mizusaki, Ana Maria Pimentel; Guerra-Sommer, Margot; Menegat, Rualdo; Barili, Rosalia; Jasper, André; Uhl, Dieter

2018-03-01

This first report of wildfires from an association of facies containing a Dicroidium flora is made from the Upper Triassic (Carnian age) in the southern part of the Paraná Basin (Santa Maria Supersequence, Rio Grande do Sul state). The geographical extension of the Dicroidium plant assemblage is augmented in Brazilian Gondwana. Field work followed by organic petrography (inertinite reflectance), scanning electron microscopy (SEM) and field emission gun scanning electron microscopy (FEG-SEM), revealed charcoal presence in a section located in Pinheiro Machado town. Macroscopic charcoal is represented by three-dimensional wood specimens assigned to gymnosperms, with coniferous affinities and by flattened, thin, elongated remains corresponding to rachises of Dicroidium. Average reflectance values between 2.80 and 6.61 %Ro measured in the macroscopic charcoals evidence high temperature burning processes, involving fires both in the crown and in the crown-surface interface. The occurrence of charcoal in distinct and subsequent facies of the studied section indicates wildfires, which affected hinterland, meso-xerophyllous coniferous assemblages and marginal hygro-mesophyllous Dicroidium-like assemblages. The integration of results from the charcoal analyses is consistent with an atmospheric oxygen content higher than 18.5% and fuel enough to generate wildfires during the Triassic of Gondwana.

Synthesis and Properties of a Clean and Sustainable Deicing Additive for Asphalt Mixture

PubMed Central

Peng, Chao; Yu, Jianying; Zhao, Zhijie; Dai, Jing; Fu, Jingyi; Zhao, Meiling; Wang, Wei

2015-01-01

A clean and sustainable deicing additive was prepared via the adsorption of acetate anions (Ac-) by magnesium (Mg) and aluminum (Al) calcined layered double hydroxide (Mg/Al-CLDH). Fourier transform infrared spectroscopy spectrums proved that Ac- had intercalated into LDH structure. X-ray diffraction patterns, scanning electron microscopy and transmission electron microscopy images showed that the intercalation spacing and platelet thickness of Mg and Al layered double hydroxide containing Ac- anions (Mg/Al-Ac- LDH) had been enlarged due to substitution of divalent CO3 2- anions by a larger quantity of monovalent Ac– anions. Differential scanning calorimetry tests testified that the insoluble Mg2/Al-Ac- LDH evidently decreased the freeze point (FP) of water to -10.68°C. X-ray photoelectron spectroscopy analyses confirmed that the Ac- were strongly confined by the metal layers of LDHs. FP test of asphalt mixtures confirmed that Mg/Al-Ac- LDHs reduced FP to -5.5°C. Immersion test results indicated that Mg/Al-Ac- LDH had a good deicing durability and Ac- did not released from asphalt mixture. Snow melting observation was conducted further testified that Mg/Al-Ac- LDH melted snow or ice sustainably. PMID:25625279

Synthesis and properties of a clean and sustainable deicing additive for asphalt mixture.

PubMed

Peng, Chao; Yu, Jianying; Zhao, Zhijie; Dai, Jing; Fu, Jingyi; Zhao, Meiling; Wang, Wei

2015-01-01

A clean and sustainable deicing additive was prepared via the adsorption of acetate anions (Ac-) by magnesium (Mg) and aluminum (Al) calcined layered double hydroxide (Mg/Al-CLDH). Fourier transform infrared spectroscopy spectrums proved that Ac- had intercalated into LDH structure. X-ray diffraction patterns, scanning electron microscopy and transmission electron microscopy images showed that the intercalation spacing and platelet thickness of Mg and Al layered double hydroxide containing Ac- anions (Mg/Al-Ac- LDH) had been enlarged due to substitution of divalent CO32- anions by a larger quantity of monovalent Ac- anions. Differential scanning calorimetry tests testified that the insoluble Mg2/Al-Ac- LDH evidently decreased the freeze point (FP) of water to -10.68°C. X-ray photoelectron spectroscopy analyses confirmed that the Ac- were strongly confined by the metal layers of LDHs. FP test of asphalt mixtures confirmed that Mg/Al-Ac- LDHs reduced FP to -5.5°C. Immersion test results indicated that Mg/Al-Ac- LDH had a good deicing durability and Ac- did not released from asphalt mixture. Snow melting observation was conducted further testified that Mg/Al-Ac- LDH melted snow or ice sustainably.

Amoebicidal activity of curcumin on Entamoeba histolytica trophozoites.

PubMed

Rangel-Castañeda, Itzia Azucena; Hernández-Hernández, José Manuel; Pérez-Rangel, Armando; González-Pozos, Sirenia; Carranza-Rosales, Pilar; Charles-Niño, Claudia Lisette; Tapia-Pastrana, Gabriela; Ramírez-Herrera, Mario Alberto; Castillo-Romero, Araceli

2018-03-01

This study was undertaken to investigate the amoebicidal potential of curcumin on Entamoeba histolytica, as well as its synergistic effect with metronidazole. Entamoeba histolytica trophozoites were exposed to 100, 200 and 300 μm of curcumin, for 6, 12 and 24 h. Consequently, the viability of cells was determined by trypan blue exclusion test. All specimens were further analysed by scanning electron microscopy. For drug combination experiment, the Chou-Talalay method was used. Curcumin affected the growth and cell viability in a time- and dose-dependent manner. The higher inhibitory effects were observed with 300 μm at 24 h; 65.5% of growth inhibition and only 28.8% of trophozoites were viable. Additionally, curcumin also altered adhesion and the morphology of the trophozoites. Scanning electron microscopy revealed treated trophozoites with damages on the membrane, size alterations and parasites with loss of cellular integrity. In addition, the combination of curcumin + metronidazole exhibited a synergistic effect; the activity of both drugs was improved. This is the first report evaluating the effectiveness of curcumin against E. histolytica. Our results suggest that CUR could be considered for evaluation in future pharmacological studies as a promising amoebicidal agent or as complementary therapy. © 2018 Royal Pharmaceutical Society.

Hydrogen-enhanced cracking revealed by in situ micro-cantilever bending test inside environmental scanning electron microscope

NASA Astrophysics Data System (ADS)

Deng, Yun; Hajilou, Tarlan; Barnoush, Afrooz

2017-06-01

To evaluate the hydrogen (H)-induced embrittlement in iron aluminium intermetallics, especially the one with stoichiometric composition of 50 at.% Al, a novel in situ micro-cantilever bending test was applied within an environmental scanning electron microscope (ESEM), which provides both a full process monitoring and a clean, in situ H-charging condition. Two sets of cantilevers were analysed in this work: one set of un-notched cantilevers, and the other set with focused ion beam-milled notch laying on two crystallographic planes: (010) and (110). The cantilevers were tested under two environmental conditions: vacuum (approximately 5 × 10-4 Pa) and ESEM (450 Pa water vapour). Crack initiation at stress-concentrated locations and propagation to cause catastrophic failure were observed when cantilevers were tested in the presence of H; while no cracking occurred when tested in vacuum. Both the bending strength for un-notched beams and the fracture toughness for notched beams were reduced under H exposure. The hydrogen embrittlement (HE) susceptibility was found to be orientation dependent: the (010) crystallographic plane was more fragile to HE than the (110) plane. This article is part of the themed issue 'The challenges of hydrogen and metals'.

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

Catalytic properties of Co3O4 nanoparticles for rechargeable Li/air batteries.

PubMed

Kim, Kwan Su; Park, Yong Joon

2012-01-05

Three types of Co3O4 nanoparticles are synthesized and characterized as a catalyst for the air electrode of a Li/air battery. The shape and size of the nanoparticles are observed using scanning electron microscopy and transmission electron microscopy analyses. The formation of the Co3O4 phase is confirmed by X-ray diffraction. The electrochemical property of the air electrodes containing Co3O4 nanoparticles is significantly associated with the shape and size of the nanoparticles. It appears that the capacity of electrodes containing villiform-type Co3O4 nanoparticles is superior to that of electrodes containing cube- and flower-type Co3O4 nanoparticles. This is probably due to the sufficient pore spaces of the villiform-type Co3O4 nanoparticles.

Photocatalytic degradation of Orange G dye under solar light using nanocrystalline semiconductor metal oxide.

PubMed

Thennarasu, G; Kavithaa, S; Sivasamy, A

2011-08-01

The photocatalytic degradation of Orange G (OG) dye has been investigated using synthesised nanocrystalline ZnO as a photocatalyst and sunlight as the irradiation source. The formation of ZnO prepared from its precursor was confirmed through FT-IR and powder X-ray diffraction analyses. Surface morphology was characterised by scanning electron microscope and transmission electron microscope analysis. Band gap energy of synthesised nanocrystalline ZnO was calculated using diffuse reflectance spectroscopy (DRS). Different experimental parameters such as effects of pH, dye concentrations and mass of catalyst were standardised in order to achieve complete degradation of the dye molecules under solar light irradiation. The kinetics of oxidation of OG was also studied. The complete degradation of OG was evident after 90 min of irradiation at an initial pH of 6.86. The degradation of OG was confirmed by UV-Visible spectrophotometer, high-pressure liquid chromatography, ESI-Mass and chemical oxygen demand analyses. The adsorption of dye onto catalytic surface was analysed employing model equations such as Langmuir and Freundlich isotherms, and it was found that the Langmuir isotherm model best fitted the adsorption data. The solar photodegradation of OG followed pseudo-first-order kinetics. HPLC and ESI-Mass analyses of the degraded samples suggested that the dye molecules were readily degraded under solar irradiation with nanocrystalline ZnO.

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

Microstructural studies of 35 degrees C copper Ni-Ti orthodontic wire and TEM confirmation of low-temperature martensite transformation.

PubMed

Brantley, William A; Guo, Wenhua; Clark, William A T; Iijima, Masahiro

2008-02-01

Previous temperature-modulated differential scanning calorimetry (TMDSC) study of nickel-titanium orthodontic wires revealed a large exothermic low-temperature peak that was attributed to transformation within martensitic NiTi. The purpose of this study was to use transmission electron microscopy (TEM) to verify this phase transformation in a clinically popular nickel-titanium wire, identify its mechanism and confirm other phase transformations found by TMDSC, and to provide detailed information about the microstructure of this wire. The 35 degrees C Copper nickel-titanium wire (Ormco) with cross-section dimensions of 0.016 in. x 0.022 in. used in the earlier TMDSC investigation was selected. Foils were prepared for TEM analyses by mechanical grinding, polishing, dimpling, ion milling and plasma cleaning. Standard bright-field and dark-field TEM images were obtained, along with convergent-beam electron diffraction patterns. A cryo-stage with the electron microscope (Phillips CM 200) permitted the specimen to be observed at -187, -45, and 50 degrees C, as well as at room temperature. Microstructures were also observed with an optical microscope and a scanning electron microscope. Room temperature microstructures had randomly oriented, elongated grains that were twinned. Electron diffraction patterns confirmed that phase transformations took place over temperature ranges previously found by TMDSC. TEM observations revealed a high dislocation density and fine-scale oxide particles, and that twinning is the mechanism for the low-temperature transformation in martensitic NiTi. TEM confirmed the low-temperature peak and other phase transformations observed by TMDSC, and revealed that twinning in martensite is the mechanism for the low-temperature peak. The high dislocation density and fine-scale oxide particles in the microstructure are the result of the wire manufacturing process.

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.

Study of corrosion in archaeological gilded irons by Raman imaging and a coupled scanning electron microscope-Raman system.

PubMed

Veneranda, Marco; Costantini, Ilaria; de Vallejuelo, Silvia Fdez-Ortiz; Garcia, Laura; García, Iñaki; Castro, Kepa; Azkarate, Agustín; Madariaga, Juan Manuel

2016-12-13

In this work, analytical and chemical imaging tools have been applied to the study of a gilded spur found in the medieval necropolis of Erenozar (Bizkaia, Spain). As a first step, a lot of portable equipment has been used to study the object in a non-invasive way. The hand-held energy-dispersive X-ray fluorescence equipment allowed us to characterize the artefact as a rare example of an iron matrix item decorated by means of a fire gilding technique. On the other hand, the use of a portable Raman system helped us to detect the main degradation compounds affecting the spur. Afterwards, further information was acquired in the laboratory by analysing detached fragments. The molecular images obtained using confocal Raman microscopy permitted us to characterize the stratigraphic succession of iron corrosions. Furthermore, the combined use of this technique with a scanning electron microscope (SEM) was achieved owing to the use of a structural and chemical analyser interface. In this way, the molecular characterization, enhanced by the magnification feature of the SEM, allowed us to identify several micrometric degradation compounds. Finally, the effectiveness of one of the most used desalination baths (NaOH) was evaluated by comparing its effects with those provided by a reference bath (MilliQ). The comparison proved that basic treatment avoided any side effects on the spur decorated by fire gilding, compensating for the lack of bibliographic documentation in this field.This article is part of the themed issue 'Raman spectroscopy in art and archaeology'. © 2016 The Author(s).

Study of corrosion in archaeological gilded irons by Raman imaging and a coupled scanning electron microscope-Raman system

NASA Astrophysics Data System (ADS)

Veneranda, Marco; Costantini, Ilaria; de Vallejuelo, Silvia Fdez-Ortiz; Garcia, Laura; García, Iñaki; Castro, Kepa; Azkarate, Agustín; Madariaga, Juan Manuel

2016-12-01

In this work, analytical and chemical imaging tools have been applied to the study of a gilded spur found in the medieval necropolis of Erenozar (Bizkaia, Spain). As a first step, a lot of portable equipment has been used to study the object in a non-invasive way. The hand-held energy-dispersive X-ray fluorescence equipment allowed us to characterize the artefact as a rare example of an iron matrix item decorated by means of a fire gilding technique. On the other hand, the use of a portable Raman system helped us to detect the main degradation compounds affecting the spur. Afterwards, further information was acquired in the laboratory by analysing detached fragments. The molecular images obtained using confocal Raman microscopy permitted us to characterize the stratigraphic succession of iron corrosions. Furthermore, the combined use of this technique with a scanning electron microscope (SEM) was achieved owing to the use of a structural and chemical analyser interface. In this way, the molecular characterization, enhanced by the magnification feature of the SEM, allowed us to identify several micrometric degradation compounds. Finally, the effectiveness of one of the most used desalination baths (NaOH) was evaluated by comparing its effects with those provided by a reference bath (MilliQ). The comparison proved that basic treatment avoided any side effects on the spur decorated by fire gilding, compensating for the lack of bibliographic documentation in this field. This article is part of the themed issue "Raman spectroscopy in art and archaeology".

Study of corrosion in archaeological gilded irons by Raman imaging and a coupled scanning electron microscope–Raman system

PubMed Central

Veneranda, Marco; Costantini, Ilaria; de Vallejuelo, Silvia Fdez-Ortiz; Garcia, Laura; García, Iñaki; Azkarate, Agustín; Madariaga, Juan Manuel

2016-01-01

In this work, analytical and chemical imaging tools have been applied to the study of a gilded spur found in the medieval necropolis of Erenozar (Bizkaia, Spain). As a first step, a lot of portable equipment has been used to study the object in a non-invasive way. The hand-held energy-dispersive X-ray fluorescence equipment allowed us to characterize the artefact as a rare example of an iron matrix item decorated by means of a fire gilding technique. On the other hand, the use of a portable Raman system helped us to detect the main degradation compounds affecting the spur. Afterwards, further information was acquired in the laboratory by analysing detached fragments. The molecular images obtained using confocal Raman microscopy permitted us to characterize the stratigraphic succession of iron corrosions. Furthermore, the combined use of this technique with a scanning electron microscope (SEM) was achieved owing to the use of a structural and chemical analyser interface. In this way, the molecular characterization, enhanced by the magnification feature of the SEM, allowed us to identify several micrometric degradation compounds. Finally, the effectiveness of one of the most used desalination baths (NaOH) was evaluated by comparing its effects with those provided by a reference bath (MilliQ). The comparison proved that basic treatment avoided any side effects on the spur decorated by fire gilding, compensating for the lack of bibliographic documentation in this field. This article is part of the themed issue ‘Raman spectroscopy in art and archaeology’. PMID:27799430

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.

Atmospheric plasma surface modifications of electrospun PCL/chitosan/PCL hybrid scaffolds by nozzle type plasma jets for usage of cell cultivation

NASA Astrophysics Data System (ADS)

Surucu, Seda; Masur, Kai; Turkoglu Sasmazel, Hilal; Von Woedtke, Thomas; Weltmann, Klaus Dieter

2016-11-01

This paper reports Ar gas, Ar + O2, Ar + O2 + N2 gas mixtures and dry air plasma modifications by atmospheric pressure argon driven kINPen and air driven Diener (PlasmaBeam) plasma jets to alter surface properties of three dimensional (3D), electrospun PCL/Chitosan/PCL layer by layer hybrid scaffolds to improve human fibroblast (MRC5) cell attachment and growth. The characterizations of the samples were done by contact angle (CA) measurements, scanning electron microscopy (SEM), X-Ray Photoelectron spectroscopy (XPS) analysis. The results showed that the plasma modification carried out under dry air and Ar + O2 + N2 gas mixtures were altered effectively the nanotopography and the functionality of the material surfaces. It was found that the samples treated with Ar + O2 + N2 gas mixtures for 1 min and dry air for 9 min have better hydrophilicity 78.9° ± 1.0 and 75.6° ± 0.1, respectively compared to the untreated samples (126.5°). Biocompatibility performance of the scaffolds was determined with alamarBlue (aB) assay and MTT assay methods, Giemsa staining, fluorescence microscope, confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) analyses. The results showed that plasma treated samples increased the hydrophilicity and oxygen functionality and topography of the surfaces significantly, thus affecting the cell viability and proliferation on/within scaffolds.

Unambiguous characterization of gunshot residue particles using scanning laser ablation and inductively coupled plasma-mass spectrometry.

PubMed

Abrego, Zuriñe; Ugarte, Ana; Unceta, Nora; Fernández-Isla, Alberto; Goicolea, M Aranzazu; Barrio, Ramón J

2012-03-06

A new method based on scanning laser ablation and inductively coupled plasma-mass spectrometry (LA-ICPMS) for the detection and identification of gunshot residue (GSR) particles from firearms discharges has been developed. Tape lifts were used to collect inorganic residues from skin surfaces. The laser ablation pattern and ICPMS conditions were optimized for the detection of metals present in GSR, such as (121)Sb, (137)Ba, and (208)Pb. Other isotopes ((27)Al, (29)Si, (31)P, (33)S, (35)Cl, (39)K, (44)Ca, (57)Fe, (60)Ni, (63)Cu, (66)Zn, and (118)Sn) were monitored during the ICPMS analyses to obtain additional information to possibly classify the GSR particles as either characteristic of GSR or consistent with GSR. In experiments with real samples, different firearms, calibers, and ammunitions were used. The performed method evaluation confirms that the developed methodology can be used as an alternative to the standard scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) technique, with the significant advantage of drastically reducing the analysis time to less than 66 min.

Mimicking lizard-like surface structures upon ultrashort laser pulse irradiation of inorganic materials

NASA Astrophysics Data System (ADS)

Hermens, U.; Kirner, S. V.; Emonts, C.; Comanns, P.; Skoulas, E.; Mimidis, A.; Mescheder, H.; Winands, K.; Krüger, J.; Stratakis, E.; Bonse, J.

2017-10-01

Inorganic materials, such as steel, were functionalized by ultrashort laser pulse irradiation (fs- to ps-range) to modify the surface's wetting behavior. The laser processing was performed by scanning the laser beam across the surface of initially polished flat sample material. A systematic experimental study of the laser processing parameters (peak fluence, scan velocity, line overlap) allowed the identification of different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures, grooves, spikes, etc.). Analyses of the surface using optical as well as scanning electron microscopy revealed morphologies providing the optimum similarity to the natural skin of lizards. For mimicking skin structures of moisture-harvesting lizards towards an optimization of the surface wetting behavior, additionally a two-step laser processing strategy was established for realizing hierarchical microstructures. In this approach, micrometer-scaled capillaries (step 1) were superimposed by a laser-generated regular array of small dimples (step 2). Optical focus variation imaging measurements finally disclosed the three dimensional topography of the laser processed surfaces derived from lizard skin structures. The functionality of these surfaces was analyzed in view of wetting properties.

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.

A novel material of cross-linked styrylpyridinium salt intercalated montmorillonite for drug delivery

PubMed Central

2014-01-01

A facile synthesis of a styrylpyridinium salt (SbQ)/montmorillonite (MMT) via cationic exchange interactions between styrylpyridinium species (specifically SbQ) and MMT platelets is reported in this work. The SbQ-MMT solutions were irradiated under ultraviolet (UV) light for a specific time to obtain the cross-linked SbQ-MMT materials. Scanning electron microscopy and atomic force microscopy analyses revealed the structures and morphologies of MMT and modified MMT. X-ray diffraction and transmission electron microscope analyses indicated that the basal spacing increased from 1.24 to 1.53 nm compared with the pristine MMT, which proved that SbQ had interacted with MMT. Thermal gravimetric analysis curves showed that the amount of SbQ in the MMT interlayers was 35.71 meq/100 g. Fourier transform infrared spectroscopy also confirmed the intercalation of SbQ species into MMT interlayers, and UV spectroscopy was used to follow up the cross-linking of SbQ-MMT. This novel material has potential applications in drug delivery, and it can also be used as an additive to improve the mechanical properties of polymers. PMID:25170328

The crystallization behavior of amorphous Ge2Sb2Te5 films induced by a multi-pulsed nanosecond laser

NASA Astrophysics Data System (ADS)

Fan, T.; Liu, F. R.; Li, W. Q.; Guo, J. C.; Wang, Y. H.; Sun, N. X.; Liu, F.

2017-09-01

In this paper, accumulated crystallization of amorphous Ge2Sb2Te5 (a-GST) films induced by a multi-pulsed nanosecond (ns) excimer laser was investigated by x-ray diffraction (XRD), atomic force microscopy, field-emission scanning electron microscopy, x-ray photoelectron spectroscopy (XPS) and a spectrophotometer. XRD analyses revealed that detectable crystallization was firstly observed in the preferred orientation (200), followed by the orientations (220) and (111) after two pulses. Optical contrast, determined by crystallinity as well as surface roughness, was found to retain a linear relation within the first three pulses. A layered growth mechanism from the top surface to the interior of a-GST films was used to explain the crystallization behavior induced by the multi-pulse ns laser. XPS analyses for bond rearrangement and electronic structure further suggested that the crystallization process was performed by generating new bonds of Ge-Te and Sb-Te after laser irradiations. This paper presents the potential of multi-level devices and tunable thermal emitters based on controllable crystallization of phase-change materials.

Structural, microstructural and vibrational analyses of the monoclinic tungstate BiLuWO6

NASA Astrophysics Data System (ADS)

Ait Ahsaine, H.; Taoufyq, A.; Patout, L.; Ezahri, M.; Benlhachemi, A.; Bakiz, B.; Villain, S.; Guinneton, F.; Gavarri, J.-R.

2014-10-01

The bismuth lutetium tungstate phase BiLuWO6 has been prepared using a solid state route with stoichiometric mixtures of oxide precursors. The obtained polycrystalline phase has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. In the first step, the crystal structure has been refined using Rietveld method: the crystal cell was resolved using monoclinic system (parameters a, b, c, β) with space group A2/m. SEM images showed the presence of large crystallites with a constant local nominal composition (BiLuW). TEM analyses showed that the actual local structure could be better represented by a superlattice (a, 2b, c, β) associated with space groups P2 or P2/m. The Raman spectroscopy showed the presence of vibrational bands similar to those observed in the compounds BiREWO6 with RE=Y, Gd, Nd. However, these vibrational bands were characterized by large full width at half maximum, probably resulting from the long range Bi/Lu disorder and local WO6 octahedron distortions in the structure.

A Novel Gas Sensor Based on MgSb2O6 Nanorods to Indicate Variations in Carbon Monoxide and Propane Concentrations

PubMed Central

Guillén-Bonilla, Héctor; Flores-Martínez, Martín; Rodríguez-Betancourtt, Verónica-María; Guillen-Bonilla, Alex; Reyes-Gómez, Juan; Gildo-Ortiz, Lorenzo; de la Luz Olvera Amador, María; Santoyo-Salazar, Jaime

2016-01-01

Bystromite (MgSb2O6) nanorods were prepared using a colloidal method in the presence of ethylenediamine, after a calcination step at 800 °C in static air. From X-ray powder diffraction analyses, a trirutile-type structure with lattice parameters a = 4.64 Å and c = 9.25 Å and space group P42/mnm was identified. Using scanning electron microscopy (SEM), microrods with sizes from 0.2 to 1.6 μm were observed. Transmission electron microscopy (TEM) analyses revealed that the nanorods had a length of ~86 nm and a diameter ~23.8 nm. The gas-sensing properties of these nanostructures were tested using pellets elaborated with powders of the MgSb2O6 oxide (calcined at 800 °C) at temperatures 23, 150, 200, 250 and 300 °C. The pellets were exposed to different concentrations of carbon monoxide (CO) and propane (C3H8) at these temperatures. The results showed that the MgSb2O6 nanorods possess excellent stability and high sensitivity in these atmospheres. PMID:26840318

A Novel Gas Sensor Based on MgSb2O6 Nanorods to Indicate Variations in Carbon Monoxide and Propane Concentrations.

PubMed

Guillén-Bonilla, Héctor; Flores-Martínez, Martín; Rodríguez-Betancourtt, Verónica-María; Guillen-Bonilla, Alex; Reyes-Gómez, Juan; Gildo-Ortiz, Lorenzo; de la Luz Olvera Amador, María; Santoyo-Salazar, Jaime

2016-01-30

Bystromite (MgSb2O6) nanorods were prepared using a colloidal method in the presence of ethylenediamine, after a calcination step at 800 °C in static air. From X-ray powder diffraction analyses, a trirutile-type structure with lattice parameters a = 4.64 Å and c = 9.25 Å and space group P4₂/mnm was identified. Using scanning electron microscopy (SEM), microrods with sizes from 0.2 to 1.6 μm were observed. Transmission electron microscopy (TEM) analyses revealed that the nanorods had a length of ~86 nm and a diameter ~23.8 nm. The gas-sensing properties of these nanostructures were tested using pellets elaborated with powders of the MgSb2O6 oxide (calcined at 800 °C) at temperatures 23, 150, 200, 250 and 300 °C. The pellets were exposed to different concentrations of carbon monoxide (CO) and propane (C3H8) at these temperatures. The results showed that the MgSb2O6 nanorods possess excellent stability and high sensitivity in these atmospheres.

Bacterial community composition characterization of a lead-contaminated Microcoleus sp. consortium.

PubMed

Giloteaux, Ludovic; Solé, Antoni; Esteve, Isabel; Duran, Robert

2011-08-01

A Microcoleus sp. consortium, obtained from the Ebro delta microbial mat, was maintained under different conditions including uncontaminated, lead-contaminated, and acidic conditions. Terminal restriction fragment length polymorphism and 16S rRNA gene library analyses were performed in order to determine the effect of lead and culture conditions on the Microcoleus sp. consortium. The bacterial composition inside the consortium revealed low diversity and the presence of specific terminal-restriction fragments under lead conditions. 16S rRNA gene library analyses showed that members of the consortium were affiliated to the Alpha, Beta, and Gammaproteobacteria and Cyanobacteria. Sequences closely related to Achromobacter spp., Alcaligenes faecalis, and Thiobacillus species were exclusively found under lead conditions while sequences related to Geitlerinema sp., a cyanobacterium belonging to the Oscillatoriales, were not found in presence of lead. This result showed a strong lead selection of the bacterial members present in the Microcoleus sp. consortium. Several of the 16S rRNA sequences were affiliated to nitrogen-fixing microorganisms including members of the Rhizobiaceae and the Sphingomonadaceae. Additionally, confocal laser scanning microscopy and scanning and transmission electron microscopy showed that under lead-contaminated condition Microcoleus sp. cells were grouped and the number of electrodense intracytoplasmic inclusions was increased.

Green chemistry approaches to leather tanning process for making chrome-free leather by unnatural amino acids.

PubMed

Krishnamoorthy, G; Sadulla, S; Sehgal, P K; Mandal, Asit Baran

2012-05-15

In the present study, green and sustainable method or eco-friendly approaches to tanning process based on unnatural D-amino acids (D-AA)-aldehyde (Ald) as a substitute for chrome-free tanning has been attempted. The distribution of optically active D-AA in tanned leather, the hydrothermal stability, the mechanical properties and resistance to collagenolytic activity of tanned leather, the evaluation of eco-friendly characteristics were investigated. Scanning electron microscopic (SEM) and Atomic force microscopic (AFM) analyses indicate the surface morphology and roughness, respectively, of the tanned leather collagen matrix. Shrinkage and Differential scanning calorimetric (DSC) analyses shows that the shrinkage temperature (T(s)) and denaturation temperature (T(d)) of tanned leather are related to the content of D-AA+Ald present in the leather matrix. It has been found that the T(s) of D-AA tanned leather is more than that of Ald tanned leather and also more or less equal to chrome tanned leather. Environmental impact assessment (EIA) shows that the developed process results in significant reduction in total solids content (TSC) and improves better biodegradability of organic compound present in the effluent compared to chrome tanning. Copyright © 2012 Elsevier B.V. All rights reserved.

Processing and performance of self-healing materials

NASA Astrophysics Data System (ADS)

Tan, P. S.; Zhang, M. Q.; Bhattacharyya, D.

2009-08-01

Two self-healing methods were implemented into composite materials with self-healing capabilities, using hollow glass fibres (HGF) and microencapsulated epoxy resin with mercaptan as the hardener. For the HGF approach, two perpendicular layers of HGF were put into an E-glass/epoxy composite, and were filled with coloured epoxy resin and hardener. The HGF samples had a novel ball indentation test method done on them. The samples were analysed using micro-CT scanning, confocal microscopy and penetrant dye. Micro-CT and confocal microscopy produced limited success, but their viability was established. Penetrant dye images showed resin obstructing flow of dye through damage regions, suggesting infiltration of resin into cracks. Three-point bend tests showed that overall performance could be affected by the flaws arising from embedding HGF in the material. For the microcapsule approach, samples were prepared for novel double-torsion tests used to generate large cracks. The samples were compared with pure resin samples by analysing them using photoelastic imaging and scanning electron microscope (SEM) on crack surfaces. Photoelastic imaging established the consolidation of cracks while SEM showed a wide spread of microcapsules with their distribution being affected by gravity. Further double-torsion testing showed that healing recovered approximately 24% of material strength.

Changes in biooxidation mechanism and transient biofilm characteristics by As(V) during arsenopyrite colonization with Acidithiobacillus thiooxidans.

PubMed

Ramírez-Aldaba, Hugo; Vázquez-Arenas, Jorge; Sosa-Rodríguez, Fabiola S; Valdez-Pérez, Donato; Ruiz-Baca, Estela; Trejo-Córdoba, Gabriel; Escobedo-Bretado, Miguel A; Lartundo-Rojas, Luis; Ponce-Peña, Patricia; Lara, René H

2018-06-01

Chemical and surface analyses are carried out using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM-EDS), atomic force microscopy (AFM), confocal laser scanning microscopy (CLSM), glow discharge spectroscopy (GDS) and extracellular surface protein quantification to thoroughly investigate the effect of supplementary As(V) during biooxidation of arsenopyrite by Acidithiobacillus thiooxidans. It is revealed that arsenic can enhance bacterial reactions during bioleaching, which can strongly influence its mobility. Biofilms occur as compact-flattened microcolonies, being progressively covered by a significant amount of secondary compounds (S n 2- , S 0 , pyrite-like). Biooxidation mechanism is modified in the presence of supplementary As(V), as indicated by spectroscopic and microscopic studies. GDS confirms significant variations between abiotic control and biooxidized arsenopyrite in terms of surface reactivity and amount of secondary compounds with and without As(V) (i.e. 6 μm depth). CLSM and protein analyses indicate a rapid modification in biofilm from hydrophilic to hydrophobic character (i.e. 1-12 h), in spite of the decrease in extracellular surface proteins in the presence of supplementary As(V) (i.e. stressed biofilms).

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

Preparation of thermally stable nanocrystalline hydroxyapatite by hydrothermal method.

PubMed

Prakash Parthiban, S; Elayaraja, K; Girija, E K; Yokogawa, Y; Kesavamoorthy, R; Palanichamy, M; Asokan, K; Narayana Kalkura, S

2009-12-01

Thermally stable hydroxyapatite (HAp) was synthesized by hydrothermal method in the presence of malic acid. X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), differential thermal analysis (DTA), thermogravimetric analysis (TGA) was done on the synthesized powders. These analyses confirmed the sample to be free from impurities and other phases of calcium phosphates, and were of rhombus morphology along with nanosized particles. IR and Raman analyses indicated the adsorption of malic acid on HAp. Thermal stability of the synthesized HAp was confirmed by DTA and TGA. The synthesized powders were thermally stable upto 1,400 degrees C and showed no phase change. The proposed method might be useful for producing thermally stable HAp which is a necessity for high temperature coating applications.

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.

Fabrication of [001]-oriented tungsten tips for high resolution scanning tunneling microscopy

PubMed Central

Chaika, A. N.; Orlova, N. N.; Semenov, V. N.; Postnova, E. Yu.; Krasnikov, S. A.; Lazarev, M. G.; Chekmazov, S. V.; Aristov, V. Yu.; Glebovsky, V. G.; Bozhko, S. I.; Shvets, I. V.

2014-01-01

The structure of the [001]-oriented single crystalline tungsten probes sharpened in ultra-high vacuum using electron beam heating and ion sputtering has been studied using scanning and transmission electron microscopy. The electron microscopy data prove reproducible fabrication of the single-apex tips with nanoscale pyramids grained by the {011} planes at the apexes. These sharp, [001]-oriented tungsten tips have been successfully utilized in high resolution scanning tunneling microscopy imaging of HOPG(0001), SiC(001) and graphene/SiC(001) surfaces. The electron microscopy characterization performed before and after the high resolution STM experiments provides direct correlation between the tip structure and picoscale spatial resolution achieved in the experiments. PMID:24434734

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.

Sonochemical synthesis and characterization of a novel hetro-binuclear metal organic nano polymer based on picolinic acid ligand

NASA Astrophysics Data System (ADS)

Hayati, Payam; Souri, Bagher; Rezvani, Ali Reza; Morsali, Ali; Gutierrez, Angel

2017-12-01

Nanoparticles of one new lead and K coordination polymer (CP), {[Pb6(pyc)6(N3)7K].½H2O}n (1) Hpyc = picolinic acid ligand, has been synthesized by use of a sonochemical process and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) spectroscopy and elemental analyses. The single crystal X-ray data of compound 1 imply that the Pb ion is seven coordinated. The thermal stability of compound 1 has been studied by thermogravimetric (TG) and differential scanning calorimetry (DSC). The role of temperature, reaction time and ultrasound irradiation power on the size and morphfology of the nano-structured compound obtained from 1, have been investigated. Results indicate that an increase of temperature and sonication power and a decrease in time reaction led to a decrease of particle size.

Biofilms of vaginal Lactobacillus in vitro test.

PubMed

Wei, Xiao-Yu; Zhang, Rui; Xiao, Bing-Bing; Liao, Qin-Ping

2017-01-01

This paper focuses on biofilms of Lactobacillus spp. - a type of normal flora isolated from healthy human vaginas of women of childbearing age; thereupon, it broadens the research scope of investigation of vaginal normal flora. The static slide culture method was adopted to foster biofilms, marked by specific fluorescence staining. Laser scanning confocal and scanning electron microscopy were used to observe the microstructure of the biofilms. Photographs taken from the microstructure were analysed to calculate the density of the biofilms. The body of Lactobacillus spp., though red, turned yellow when interacting with the green extracellular polysaccharides. The structure of the biofilm and aquaporin within the biofilm were imaged. Lactobacillus density increases over time. This study provides convincing evidence that Lactobacillus can form biofilms and grow over time in vitro. This finding establishes an important and necessary condition for selecting proper strains for the pharmaceutics of vaginal ecology.

Characterization of multiwalled carbon nanotube-polymethyl methacrylate composite resins as denture base materials.

PubMed

Wang, Russell; Tao, Junliang; Yu, Bill; Dai, Liming

2014-04-01

Most fractures of dentures occur during function, primarily because of the flexural fatigue of denture resins. The purpose of this study was to evaluate a polymethyl methacrylate denture base material modified with multiwalled carbon nanotubes in terms of fatigue resistance, flexural strength, and resilience. Denture resin specimens were fabricated: control, 0.5 wt%, 1 wt%, and 2 wt% of multiwalled carbon nanotubes. Multiwalled carbon nanotubes were dispersed by sonication. Thermogravimetric analysis was used to determine quantitative dispersions of multiwalled carbon nanotubes in polymethyl methacrylate. Raman spectroscopic analyses were used to evaluate interfacial reactions between the multiwalled carbon nanotubes and the polymethyl methacrylate matrix. Groups with and without multiwalled carbon nanotubes were subjected to a 3-point-bending test for flexural strength. Resilience was derived from a stress and/or strain curve. Fatigue resistance was conducted by a 4-point bending test. Fractured surfaces were analyzed by scanning electron microscopy. One-way ANOVA and the Duncan tests were used to identify any statistical differences (α=.05). Thermogravimetric analysis verified the accurate amounts of multiwalled carbon nanotubes dispersed in the polymethyl methacrylate resin. Raman spectroscopy showed an interfacial reaction between the multiwalled carbon nanotubes and the polymethyl methacrylate matrix. Statistical analyses revealed significant differences in static and dynamic loadings among the groups. The worst mechanical properties were in the 2 wt% multiwalled carbon nanotubes (P<.05), and 0.5 wt% and 1 wt% multiwalled carbon nanotubes significantly improved flexural strength and resilience. All multiwalled carbon nanotubes-polymethyl methacrylate groups showed poor fatigue resistance. The scanning electron microscopy results indicated more agglomerations in the 2% multiwalled carbon nanotubes. Multiwalled carbon nanotubes-polymethyl methacrylate groups (0.5% and 1%) performed better than the control group during the static flexural test. The results indicated that 2 wt% multiwalled carbon nanotubes were not beneficial because of the inadequate dispersion of multiwalled carbon nanotubes in the polymethyl methacrylate matrix. Scanning electron microscopy analysis showed agglomerations on the fracture surface of 2 wt% multiwalled carbon nanotubes. The interfacial bonding between multiwalled carbon nanotubes and polymethyl methacrylate was weak based on the Raman data and dynamic loading results. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Reconstruction of the 3-D Shape and Crystal Preferred Orientation of Olivine: A Combined X-ray µ-CT and EBSD-SEM approach

NASA Astrophysics Data System (ADS)

Kahl, Wolf-Achim; Hidas, Károly; Dilissen, Nicole; Garrido, Carlos J.; López-Sánchez Vizcaíno, Vicente; Jesús Román-Alpiste, Manuel

2017-04-01

The complete reconstruction of the microstructure of rocks requires, among others, a full description of the shape preferred orientation (SPO) and crystal preferred orientation (CPO) of the constituent mineral phases. New advances in instrumental analyses, particularly electron backscatter diffraction (EBSD) coupled to focused ion beam-scanning electron microscope (FIB-SEM), allows a complete characterization of SPO and CPO in rocks at the micron scale [1-2]. Unfortunately, the large grain size of many crystalline rocks, such as peridotite, prevents a representative characterization of the CPO and SPO of their constituent minerals by this technique. Here, we present a new approach combining X-ray micro computed tomography (µ-CT) and EBSD to reconstruct the geographically oriented, 3-D SPO and CPO of cm- to mm-sized olivine crystals in two contrasting fabric types of chlorite harzburgites (Almírez ultramafic massif, SE Spain). The semi-destructive sample treatment involves drilling of geographically oriented micro drills in the field and preparation of oriented thin sections from µ-CT scanned cores. This allows for establishing the link among geological structures, macrostructure, fabric, and 3-D SPO-CPO at the thin section scale. Based on EBSD analyses, different CPO groups of olivine crystals can be discriminated in the thin sections and allocated to 3-D SPO in the µ-CT volume data. This approach overcomes the limitations of both methods (i.e., no crystal orientation data in µ-CT and no spatial information in EBSD), hence 3-D orientation of the crystallographic axes of olivines from different orientation groups could be correlated with the crystal shapes of olivine grains. This combined µ-CT and EBSD technique enables the correlation of both SPO and CPO and representative grain size, and is capable to characterize the 3-D microstructure of olivine-bearing rocks at the hand specimen scale. REFERENCES 1. Zaefferer, S., Wright, S.I., Raabe, D., 2008. Three-Dimensional orientation microscopy in a focused ion beam-scanning electron microscope: A new dimension of microstructure characterization. Metallurgical and Materials Transactions A 39, 374-389. 2. Burnett, T.L., Kelley, R., Winiarski, B., Contreras, L., Daly, M., Gholinia, A., Burke, M.G., Withers, P.J., 2016. Large volume serial section tomography by Xe Plasma FIB dual beam microscopy. Ultramicroscopy 161, 119-129.

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.

Martian dunite NWA 2737: Integrated spectroscopic analyses of brown olivine

NASA Astrophysics Data System (ADS)

Pieters, Carle M.; Klima, Rachel L.; Hiroi, Takahiro; Dyar, M. Darby; Lane, Melissa D.; Treiman, Allan H.; Noble, Sarah K.; Sunshine, Jessica M.; Bishop, Janice L.

2008-06-01

A second Martian meteorite has been identified that is composed primarily of heavily shocked dunite, Northwest Africa (NWA) 2737. This meteorite has several similarities to the Chassigny dunite cumulate, but the olivine is more Mg rich and, most notably, is very dark and visually brown. Carefully coordinated analyses of NWA 2737 whole-rock and olivine separates were undertaken using visible and near-infrared reflectance, midinfrared emission and reflectance, and Mössbauer spectroscopic studies of the same samples along with detailed petrography, chemistry, scanning electron microscopy, and transmission electron microscopy analyses. Midinfrared spectra of this sample indicate that the olivine is fully crystalline and that its molecular structure remains intact. The unusual color and spectral properties that extend from the visible through the near-infrared part of the spectrum are shown to be due to nanophase metallic iron particles dispersed throughout the olivine during a major shock event on Mars. Although a minor amount of Fe3+ is present, it cannot account for the well-documented unusual optical properties of Martian meteorite NWA 2737. Perhaps unique to the Martian environment, this ``brown'' olivine exhibits spectral properties that can potentially be used to remotely explore the pressure-temperature history of surface geology as well as assess surface composition.

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

The use of a fully integrated electronic medical record to minimize cumulative lifetime radiation exposure from CT scanning to detect urinary tract calculi.

PubMed

Kohler, Steven W; Chen, Richard; Kagan, Alex; Helvey, Dustin W; Buccigrossi, David

2013-06-01

In order to determine the effects of implementation of an electronic medical record on rates of repeat computed tomography (CT) scanning in the emergency department (ED) setting, we analyzed the utilization of CT of the kidneys, ureters, and bladder (CT KUB) for the detection of urinary tract calculi for periods before and after the implementation of a hospital-wide electronic medical record system. Rates of repeat CT scanning within a 6-month period of previous scan were determined pre- and post-implementation and compared. Prior to implementation, there was a 6-month repeat rate of 6.2 % compared with the post-implementation period, which was associated with a 6-month repeat rate of 4.1 %. Statistical analysis using a two-sample, one-tailed t test for difference of means was associated with a p value of 0.00007. This indicates that the implementation of the electronic medical record system was associated with a 34 % decrease in 6-month repeat CT KUB scans. We conclude that the use of an electronic medical record can be associated with a decrease in utilization of unnecessary repeat CT imaging, leading to decreased cumulative lifetime risk for cancer in these patients and more efficient utilization of ED and radiologic resources.

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.

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.

Electron Beam-Induced Writing of Nanoscale Iron Wires on a Functional Metal Oxide

PubMed Central

2013-01-01

Electron beam-induced surface activation (EBISA) has been used to grow wires of iron on rutile TiO2(110)-(1 × 1) in ultrahigh vacuum. The wires have a width down to ∼20 nm and hence have potential utility as interconnects on this dielectric substrate. Wire formation was achieved using an electron beam from a scanning electron microscope to activate the surface, which was subsequently exposed to Fe(CO)5. On the basis of scanning tunneling microscopy and Auger electron spectroscopy measurements, the activation mechanism involves electron beam-induced surface reduction and restructuring. PMID:24159366

Aquatic Fern (Azolla Sp.) Assisted Synthesis of Gold Nanoparticles

NASA Astrophysics Data System (ADS)

Jha, Anal K.; Prasad, K.

2016-02-01

Aquatic pteridophyte (Azolla sp.) was taken to assess its potential to synthesize the metal (Au) nanoparticles. The synthesized particles were characterized using X-ray, UV-visible, scanning and transmission electron microscopy analyses. Nanoparticles almost spherical in shape having the sizes of 5-17nm are found. UV-visible study revealed the surface plasmon resonance at 538nm. Responsible phytochemicals for the transformation were principally phenolics, tannins, anthraquinone glycosides and sugars present abundantly in the plant thereby bestowing it adaptive prodigality. Also, the use of Azolla sp. for the synthesis of gold nanoparticles offers the benefit of eco-friendliness.

Self-standing crystalline TiO2 nanotubes/CNTs heterojunction membrane: synthesis and characterization.

PubMed

Hesabi, Zohreh R; Allam, Nageh K; Dahmen, Klaus; Garmestani, Hamid; A El-Sayed, Mostafa

2011-04-01

In the present study, we report for the first time synthesis of TiO(2) nanotubes/CNTs heterojunction membrane. Chemical vapor deposition (CVD) of CNTs at 650 °C in a mixture of H(2)/He atmosphere led to in situ detachment of the anodically fabricated TiO(2) nanotube layers from the Ti substrate underneath. Morphological and structural evolution of TiO(2) nanotubes after CNTs deposition were investigated by field- emission scanning electron microscopy (FESEM), glancing angle X-ray diffraction (GAXRD), and X-ray photoelectron spectroscopy (XPS) analyses. © 2011 American Chemical Society

Small Particle Impact Damage on Different Glass Substrates

NASA Technical Reports Server (NTRS)

Waxman, R.; Guven, I.; Gray, P.

2017-01-01

Impact experiments using sand particles were performed on four distinct glass substrates. The sand particles were characterized using the X-Ray micro-CT technique; 3-D reconstruction of the particles was followed by further size and shape analyses. High-speed video footage from impact tests was used to calculate the incoming and rebound velocities of the individual sand impact events, as well as particle volume. Further, video analysis was used in conjunction with optical and scanning electron microscopy to relate the incoming velocity and shape of the particles to subsequent fractures, including both radial and lateral cracks. Analysis was performed using peridynamic simulations.

Enhanced efficiency and air-stability of NiOX-based perovskite solar cells via PCBM electron transport layer modification with Triton X-100.

PubMed

Lee, Kisu; Ryu, Jaehoon; Yu, Haejun; Yun, Juyoung; Lee, Jungsup; Jang, Jyongsik

2017-11-02

We modified phenyl-C61-butyric acid methyl ester (PCBM) for use as a stable, efficient electron transport layer (ETL) in inverted perovskite solar cells (PSCs). PCBM containing a surfactant Triton X-100 acts as the ETL and NiO X nanocrystals act as a hole transport layer (HTL). Atomic force microscopy and scanning electron microscopy images showed that surfactant-modified PCBM (s-PCBM) forms a high-quality, uniform, and dense ETL on the rough perovskite layer. This layer effectively blocks holes and reduces interfacial recombination. Steady-state photoluminescence and electrochemical impedance spectroscopy analyses confirmed that Triton X-100 improved the electron extraction performance of PCBM. When the s-PCBM ETL was used, the average power conversion efficiency increased from 10.76% to 15.68%. This improvement was primarily caused by the increases in the open-circuit voltage and fill factor. s-PCBM-based PSCs also showed good air-stability, retaining 83.8% of their initial performance after 800 h under ambient 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.

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.

Correlated petrographic, electron microprobe, and ion microprobe studies of selected primitive and processed phase assemblages in meteorites

NASA Technical Reports Server (NTRS)

Albee, Arden L.

1993-01-01

During the past three years we have received support to continue our research in elucidating the formation and alteration histories of selected meteoritic materials by a combination of petrographic, trace element, and isotopic analyses employing optical and scanning electron microscopes and electron and ion microprobes. The awarded research funds enabled the P.I. to attend the annual LPSC, the co-I to devote approximately 15 percent of his time to the research proposed in the grant, and partial support for a visiting summer post-doctoral fellow to conduct electron microprobe analyses of meteoritic samples in our laboratory. The research funds, along with support from the NASA Education Initiative awarded to P.I. G. Wasserburg, enabled the co-I to continue a mentoring program with inner-city minority youth. The support enabled us to achieve significant results in the five projects that we proposed (in addition to the Education Initiative), namely: studies of the accretional and post-accretional alteration and thermal histories in CV meteorites, characterization of periclase-bearing Fremdlinge in CV meteorites, characterization of Ni-Pt-Ge-Te-rich Fremdlinge in CV meteorites in an attempt to determine the constraints they place on the petrogenetic and thermal histories of their host CAI's, correlated electron and ion microprobe studies of silicate and phosphate inclusions in the Colomera meteorite in an attempt to determine the petrogenesis of the IE iron meteorites, and development of improved instrumental and correction procedures for improved accuracy of analysis of meteoritic materials with the electron microprobe. This grant supported, in part or whole, 18 publications so far by our research team, with at least three more papers anticipated. The list of these publications is included. The details of the research results are briefly summarized.

The Role of Phase Changes in TiO2/Pt/TiO2 Filaments

NASA Astrophysics Data System (ADS)

Bíró, Ferenc; Hajnal, Zoltán; Dücső, Csaba; Bársony, István

2018-04-01

This work analyses the role of phase changes in TiO2/Pt/TiO2 layer stacks for micro-heater application regarding their stability and reliable operation. The polycrystalline Pt layer wrapped in a TiO2 adhesion layer underwent a continuous recrystallisation in a self-heating operation causing a drift in the resistance ( R) versus temperature ( T) performance. Simultaneously, the TiO2 adhesion layer also deteriorates at high temperature by phase changes from amorphous to anatase and rutile crystallite formation, which not only influences the Pt diffusion in different migration phenomena, but also reduces the cross section of the Pt heater wire. Thorough scanning electron microscopy, energy dispersive spectroscopy, cross-sectional transmission electron microscopy (XTEM) and electron beam diffraction analysis of the structures operated at increasing temperature revealed the elemental structural processes leading to the instabilities and the accelerated degradation, resulting in rapid breakdown of the heater wire. Owing to stability and reliability criteria, the conditions for safe operation of these layer structures could be determined.

Systematic investigation on Cadmium-incorporation in Li₂FeSiO₄/C cathode material for lithium-ion batteries.

PubMed

Zhang, Lu-Lu; Duan, Song; Yang, Xue-Lin; Liang, Gan; Huang, Yun-Hui; Cao, Xing-Zhong; Yang, Jing; Ni, Shi-Bing; Li, Ming

2014-05-27

Cadmium-incorporated Li2FeSiO4/C composites have been successfully synthesized by a solid-state reaction assisted with refluxing. The effect and mechanism of Cd-modification on the electrochemical performance of Li2FeSiO4/C were investigated in detail by X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Raman spectra, transmission electron microscopy, positron annihilation lifetime spectroscopy and Doppler broadening spectrum, and electrochemical measurements. The results show that Cd not only exists in an amorphous state of CdO on the surface of LFS particles, but also enters into the crystal lattice of LFS. Positron annihilation lifetime spectroscopy and Doppler broadening spectrum analyses verify that Cd-incorporation increases the defect concentration and the electronic conductivity of LFS, thus improve the Li(+)-ion diffusion process. Furthermore, our electrochemical measurements verify that an appropriate amount of Cd-incorporation can achieve a satisfied electrochemical performance for LFS/C cathode material.

Electron microscope observations of impact crater debris amongst contaminating particulates on materials surfaces exposed in space in low-Earth orbit

NASA Technical Reports Server (NTRS)

Murr, L. E.; Rivas, J. M.; Quinones, S.; Niou, C.-S.; Advani, A. H.; Marquez, B.

1993-01-01

Debris particles extracted from a small sampling region on the leading edge of the Long Duration Exposure Facility (LDEF) spacecraft have been examined by analytical transmission electron microscopy and the elemental frequency observed by energy-dispersive X-ray spectrometry and compared with upper atmosphere (Earth) particle elemental frequency and the average elemental compositions of interplanetary dust particles. A much broader elemental distribution was observed for the exposed spacecraft surface debris milieu. Numerous metal microfragment analyses, particularly aluminum and stainless steel, were compared with scanning electron microscope observations-of impact crater features, and the corresponding elemental spectra on selected LDEF aluminium tray clamps and stainless steel bolts. The compositions and melt features for these impact craters and ejecta have been shown to be consistent with microcrystalline debris fragments in the case of aluminum, and these observations suggest an ever changing debris milieu on exposed surfaces for space craft and space system materials.

Probing the electrical switching of a memristive optical antenna by STEM EELS

PubMed Central

Schoen, David T.; Holsteen, Aaron L.; Brongersma, Mark L.

2016-01-01

The scaling of active photonic devices to deep-submicron length scales has been hampered by the fundamental diffraction limit and the absence of materials with sufficiently strong electro-optic effects. Plasmonics is providing new opportunities to circumvent this challenge. Here we provide evidence for a solid-state electro-optical switching mechanism that can operate in the visible spectral range with an active volume of less than (5 nm)3 or ∼10−6 λ3, comparable to the size of the smallest electronic components. The switching mechanism relies on electrochemically displacing metal atoms inside the nanometre-scale gap to electrically connect two crossed metallic wires forming a cross-point junction. These junctions afford extreme light concentration and display singular optical behaviour upon formation of a conductive channel. The active tuning of plasmonic antennas attached to such junctions is analysed using a combination of electrical and optical measurements as well as electron energy loss spectroscopy in a scanning transmission electron microscope. PMID:27412052

Systematic investigation on Cadmium-incorporation in Li2FeSiO4/C cathode material for lithium-ion batteries

PubMed Central

Zhang, Lu-Lu; Duan, Song; Yang, Xue-Lin; Liang, Gan; Huang, Yun-Hui; Cao, Xing-Zhong; Yang, Jing; Ni, Shi-Bing; Li, Ming

2014-01-01

Cadmium-incorporated Li2FeSiO4/C composites have been successfully synthesized by a solid-state reaction assisted with refluxing. The effect and mechanism of Cd-modification on the electrochemical performance of Li2FeSiO4/C were investigated in detail by X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Raman spectra, transmission electron microscopy, positron annihilation lifetime spectroscopy and Doppler broadening spectrum, and electrochemical measurements. The results show that Cd not only exists in an amorphous state of CdO on the surface of LFS particles, but also enters into the crystal lattice of LFS. Positron annihilation lifetime spectroscopy and Doppler broadening spectrum analyses verify that Cd-incorporation increases the defect concentration and the electronic conductivity of LFS, thus improve the Li+-ion diffusion process. Furthermore, our electrochemical measurements verify that an appropriate amount of Cd-incorporation can achieve a satisfied electrochemical performance for LFS/C cathode material. PMID:24860942

Biosynthesis of silver nanoparticles using aqueous leaf extract of Thevetia peruviana Juss and its antimicrobial activities

NASA Astrophysics Data System (ADS)

Oluwaniyi, Omolara O.; Adegoke, Haleemat I.; Adesuji, Elijah T.; Alabi, Aderemi B.; Bodede, Sunday O.; Labulo, Ayomide H.; Oseghale, Charles O.

2016-08-01

Biosynthesizing of silver nanoparticles using microorganisms or various plant parts have proven more environmental friendly, cost-effective, energy saving and reproducible when compared to chemical and physical methods. This investigation demonstrated the plant-mediated synthesis of silver nanoparticles using the aqueous leaf extract of Thevetia peruviana. UV-Visible spectrophotometer was used to measure the surface plasmon resonance of the nanoparticles at 460 nm. Fourier Transform Infrared showed that the glycosidic -OH and carbonyl functional group present in extract were responsible for the reduction and stabilization of the silver nanoparticles. X ray diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy and Selected Area Electron Diffraction analyses were used to confirm the nature, morphology and shape of the nanoparticles. The silver nanoparticles are spherical in shape with average size of 18.1 nm. The synthesized silver nanoparticles showed activity against fungal pathogens and bacteria. The zone of inhibition observed in the antimicrobial study ranged between 10 and 20 mm.

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.

Crystallography of refractory metal nuggets in carbonaceous chondrites: A transmission Kikuchi diffraction approach

NASA Astrophysics Data System (ADS)

Daly, Luke; Bland, Phil A.; Dyl, Kathryn A.; Forman, Lucy V.; Saxey, David W.; Reddy, Steven M.; Fougerouse, Denis; Rickard, William D. A.; Trimby, Patrick W.; Moody, Steve; Yang, Limei; Liu, Hongwei; Ringer, Simon P.; Saunders, Martin; Piazolo, Sandra

2017-11-01

Transmission Kikuchi diffraction (TKD) is a relatively new technique that is currently being developed for geological sample analysis. This technique utilises the transmission capabilities of a scanning electron microscope (SEM) to rapidly and accurately map the crystallographic and geochemical features of an electron transparent sample. TKD uses a similar methodology to traditional electron backscatter diffraction (EBSD), but is capable of achieving a much higher spatial resolution (5-10 nm) (Trimby, 2012; Trimby et al., 2014). Here we apply TKD to refractory metal nuggets (RMNs) which are micrometre to sub-micrometre metal alloys composed of highly siderophile elements (HSEs) found in primitive carbonaceous chondrite meteorites. TKD allows us to analyse RMNs in situ, enabling the characterisation of nanometre-scale variations in chemistry and crystallography, whilst preserving their spatial and crystallographic context. This provides a complete representation of each RMN, permitting detailed interpretation of their formation history. We present TKD analysis of five transmission electron microscopy (TEM) lamellae containing RMNs coupled with EBSD and TEM analyses. These analyses revealed textures and relationships not previously observed in RMNs. These textures indicate some RMNs experienced annealing, forming twins. Some RMNs also acted as nucleation centres, and formed immiscible metal-silicate fluids. In fact, each RMN analysed in this study had different crystallographic textures. These RMNs also had heterogeneous compositions, even between RMNs contained within the same inclusion, host phase and even separated by only a few nanometres. Some RMNs are also affected by secondary processes at low temperature causing exsolution of molybdenite. However, most RMNs had crystallographic textures indicating that the RMN formed prior to their host inclusion. TKD analyses reveal most RMNs have been affected by processing in the protoplanetary disk. Despite this alteration, RMNs still preserve primary crystallographic textures and heterogeneous chemical signatures. This heterogeneity in crystallographic relationships, which mostly suggest that RMNs pre-date their host, is consistent with the idea that there is not a dominant RMN forming process. Each RMN has experienced a complex history, supporting the suggestion of Daly et al. (2017), that RMNs may preserve a diverse pre-solar chemical signature inherited from the Giant Molecular Cloud.

Nanoscale electron manipulation in metals with intense THz electric fields

NASA Astrophysics Data System (ADS)

Takeda, Jun; Yoshioka, Katsumasa; Minami, Yasuo; Katayama, Ikufumi

2018-03-01

Improved control over the electromagnetic properties of metals on a nanoscale is crucial for the development of next-generation nanoelectronics and plasmonic devices. Harnessing the terahertz (THz)-electric-field-induced nonlinearity for the motion of electrons is a promising method of manipulating the local electromagnetic properties of metals, while avoiding undesirable thermal effects and electronic transitions. In this review, we demonstrate the manipulation of electron delocalization in ultrathin gold (Au) films with nanostructures, by intense THz electric-field transients. On increasing the electric-field strength of the THz pulses, the transmittance in the THz-frequency region abruptly decreases around the percolation threshold. The observed THz-electric-field-induced nonlinearity is analysed, based on the Drude-Smith model. The results suggest that ultrafast electron delocalization occurs by electron tunnelling across the narrow insulating bridge between the Au nanostructures, without material breakdown. In order to quantitatively discuss the tunnelling process, we perform scanning tunnelling microscopy with carrier-envelope phase (CEP)-controlled single-cycle THz electric fields. By applying CEP-controlled THz electric fields to the 1 nm nanogap between a metal nanotip and graphite sample, many electrons could be coherently driven through the quantum tunnelling process, either from the nanotip to the sample or vice versa. The presented concept, namely, electron tunnelling mediated by CEP-controlled single-cycle THz electric fields, can facilitate the development of nanoscale electron manipulation, applicable to next-generation ultrafast nanoelectronics and plasmonic devices.

Diffraction effects and inelastic electron transport in angle-resolved microscopic imaging applications.

PubMed

Winkelmann, A; Nolze, G; Vespucci, S; Naresh-Kumar, G; Trager-Cowan, C; Vilalta-Clemente, A; Wilkinson, A J; Vos, M

2017-09-01

We analyse the signal formation process for scanning electron microscopic imaging applications on crystalline specimens. In accordance with previous investigations, we find nontrivial effects of incident beam diffraction on the backscattered electron distribution in energy and momentum. Specifically, incident beam diffraction causes angular changes of the backscattered electron distribution which we identify as the dominant mechanism underlying pseudocolour orientation imaging using multiple, angle-resolving detectors. Consequently, diffraction effects of the incident beam and their impact on the subsequent coherent and incoherent electron transport need to be taken into account for an in-depth theoretical modelling of the energy- and momentum distribution of electrons backscattered from crystalline sample regions. Our findings have implications for the level of theoretical detail that can be necessary for the interpretation of complex imaging modalities such as electron channelling contrast imaging (ECCI) of defects in crystals. If the solid angle of detection is limited to specific regions of the backscattered electron momentum distribution, the image contrast that is observed in ECCI and similar applications can be strongly affected by incident beam diffraction and topographic effects from the sample surface. As an application, we demonstrate characteristic changes in the resulting images if different properties of the backscattered electron distribution are used for the analysis of a GaN thin film sample containing dislocations. © 2017 The Authors. Journal of Microscopy published by JohnWiley & Sons Ltd on behalf of Royal Microscopical Society.

Experimentally determined wear behavior of an Al2O3-SiC composite from 25 to 1200 C

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher; Farmer, Serene C.; Book, Patricia O.

1990-01-01

The sliding wear behavior of a self-mated alumina-silicon carbide whisker toughened composite was studied using optical, scanning electron (SEM) and transmission electron (TEM) microscopy. Because of its excellent strength and toughness properties this composite material is under consideration for use in heat engine applications for sliding contacts which operate at elevated temperatures. The composite's wear behavior and especially its wear mechanisms are not well understood. Pin-on-disk specimens were slid in air at 2.7 m/s sliding velocity, under a 26.5-N load, at temperatures 25 to 1200 C. Pin wear increased with increasing temperature. Based upon the microscopic analyses, the wear mechanism seems to be loosening of the reinforcing whiskers due to frictional and bulk heating. This leads to whisker pullout and increased wear.

Studies on the chemical synthesis and characterization of lead oxide nanoparticles with different organic capping agents

NASA Astrophysics Data System (ADS)

Arulmozhi, K. T.; Mythili, N.

2013-12-01

Lead oxide (PbO) nanoparticles were chemically synthesized using Lead (II) acetate as precursor. The effects of organic capping agents such as Oleic acid, Ethylene Diamine Tetra Acetic acid (EDTA) and Cetryl Tri Methyl Butoxide (CTAB) on the size and morphology of the nanoparticles were studied. Characterization techniques such as X-ray diffraction (XRD), Fourier Transform-Infrared spectroscopy (FT-IR), Photoluminescence (PL) Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy (EDS) and Transmission Electron Microscopy (TEM) were used to analyse the prepared nanoparticles for their physical, structural and optical properties. The characterization studies reveal that the synthesized PbO nanoparticles had well defined crystalline structure and sizes in the range of 25 nm to 36 nm for capping agents used and 40 nm for pure PbO nanoparticles.

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

Electrochemical oxygen reduction behavior of selectively deposited platinum atoms on gold nanoparticles.

PubMed

Sarkar, A; Kerr, J B; Cairns, E J

2013-07-22

Carbon-supported Pt@Au "core-shell" nanoparticles with varying surface concentration of platinum atoms have been synthesized using a novel redox-mediated synthesis approach. The synthesis technique allows for a selective deposition of platinum atoms on the surface of prefabricated gold nanoparticles. Energy dispersive spectroscopic analyses in a scanning electron microscope reveal that the platinum to gold atomic ratios are close to the nominal values, validating the synthesis scheme. X-ray diffraction data indicate an un-alloyed structure. The platinum to gold surface atomic ratio determined from cyclic voltammetry and copper under-potential deposition experiments reveal good agreement with the calculated values at low platinum concentration. However, there is an increase in non-uniformity in the deposition process upon increasing the platinum concentration. Koutecky-Levich analysis of the samples indicates a transition of the total number of electrons transferred (n) in the electrochemical oxygen reduction reaction from two to four electrons upon increasing the surface concentration of platinum atoms. Furthermore, the data indicate that isolated platinum atoms can reduce molecular oxygen but via a two-electron route. Moreover, successful four-electron reduction of molecular oxygen requires clusters of platinum atoms. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterisation of metals in the electronic waste of complex mixtures of end-of-life ICT products for development of cleaner recovery technology

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

Sun, Z.H.I.; Xiao, Y.; Sietsma, J.

2015-01-15

Highlights: • New characterisation methodology has been established to understand an industrially processed ICT waste. • Particle size distribution, composition, thermal–chemical behaviour and occurrence of metals were considered. • The characterisation provides direct guidelines for values recovery from the waste. - Abstract: Recycling of valuable metals from electronic waste, especially complex mixtures of end-of-life information and communication technology (ICT) products, is of great difficulty due to their complexity and heterogeneity. One of the important reasons is the lack of comprehensive characterisation on such materials, i.e. accurate compositions, physical/chemical properties. In the present research, we focus on developing methodologies for themore » characterisation of metals in an industrially processed ICT waste. The morphology, particle size distribution, compositional distribution, occurrence, liberation as well as the thermo-chemical properties of the ICT waste were investigated with various characterisation techniques, including X-ray Fluorescence Spectrometry (XRF), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) with energy dispersed spectroscopy (EDS). Due to the high heterogeneity of the material, special sample preparation procedures were introduced to minimise the discrepancies during compositional analyses. As a result, a clearer overview of the ICT waste has been reached. This research provides better understanding of the extractability of each metal and improves the awareness of potential obstacles for extraction. It will lead to smarter decisions during further development of a clean and effective recovery process.« less

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.

Local 2D-2D tunneling in high mobility electron systems

NASA Astrophysics Data System (ADS)

Pelliccione, Matthew; Sciambi, Adam; Bartel, John; Goldhaber-Gordon, David; Pfeiffer, Loren; West, Ken; Lilly, Michael; Bank, Seth; Gossard, Arthur

2012-02-01

Many scanning probe techniques have been utilized in recent years to measure local properties of high mobility two-dimensional (2D) electron systems in GaAs. However, most techniques lack the ability to tunnel into the buried 2D system and measure local spectroscopic information. We report scanning gate measurements on a bilayer GaAs/AlGaAs heterostructure that allows for a local modulation of tunneling between two 2D electron layers. We call this technique Virtual Scanning Tunneling Microscopy (VSTM) [1,2] as the influence of the scanning gate is analogous to an STM tip, except at a GaAs/AlGaAs interface instead of a surface. We will discuss the spectroscopic capabilities of the technique, and show preliminary results of measurements on a high mobility 2D electron system.[1] A. Sciambi, M. Pelliccione et al., Appl. Phys. Lett. 97, 132103 (2010).[2] A. Sciambi, M. Pelliccione et al., Phys. Rev. B 84, 085301 (2011).

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.

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.

Mode of action studies on the formation of enamel minerals from a novel toothpaste containing calcium silicate and sodium phosphate salts.

PubMed

Sun, Yuekui; Li, Xiaoke; Deng, Yan; Sun, Jianing N; Tao, DanYing; Chen, Hui; Hu, Qinghong; Liu, Renjiang; Liu, Weining; Feng, Xiping; Wang, Jinfang; Carvell, Mel; Joiner, Andrew

2014-06-01

To investigate in vitro and in situ the deposition and formation of hydroxyapatite (HAP) on enamel surfaces following brushing with a novel toothpaste containing calcium silicate (CaSi), sodium phosphate salts and fluoride. Polished enamel blocks were brushed in vitro with a slurry of the CaSi toothpaste. After one brush and four weeks simulated brushing the enamel surfaces were analysed. In an in situ protocol, enamel blocks were attached to first or second molar teeth of healthy subjects, exposed to 4 weeks twice per day brushing with the CaSi toothpaste and then analysed. The surface deposits were analysed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). In addition, the CaSi toothpaste was slurried in simulated oral fluid (SOF) over a 3 hour period and the solids were isolated and analysed by Fourier transform infrared spectroscopy (FTIR). The FTIR study demonstrated that calcium phosphate phases had formed and these became increasingly crystalline over 3 hours. CaSi was deposited onto enamel surfaces following one brushing with the toothpaste in vitro.The deposited particles showed evidence of HAP crystalline phases associated with the CaSi. Following 4 weeks brushing in vitro, the deposition increased and analyses showed that the deposited material was HAP. These results were confirmed by the in situ study. Calcium silicate can be deposited onto enamel surfaces from a novel toothpaste formulation where it can form the enamel mineral HAP. A novel toothpaste formulation containing CaSi can form HAP on enamel surfaces. The potential of this technology is for a novel approach to the repair of demineralised enamel and the protection of enamel during acid exposure. © 2014 Elsevier Ltd. All rights reserved.

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).

a High-Density Electron Beam and Quad-Scan Measurements at Pleiades Thomson X-Ray Source

NASA Astrophysics Data System (ADS)

Lim, J. K.; Rosenzweig, J. B.; Anderson, S. G.; Tremaine, A. M.

2007-09-01

A recent development of the photo-cathode injector technology has greatly enhanced the beam quality necessary for the creation of high density/high brightness electron beam sources. In the Thomson backscattering x-ray experiment, there is an immense need for under 20 micron electron beam spot at the interaction point with a high-intensity laser in order to produce a large x-ray flux. This has been demonstrated successfully at PLEIADES in Lawrence Livermore National Laboratory. For this Thomson backscattering experiment, we employed an asymmetric triplet, high remanence permanent-magnet quads to produce smaller electron beams. Utilizing highly efficient optical transition radiation (OTR) beam spot imaging technique and varying electron focal spot sizes enabled a quadrupole scan at the interaction zone. Comparisons between Twiss parameters obtained upstream to those parameter values deduced from PMQ scan will be presented in this report.

a High-Density Electron Beam and Quad-Scan Measurements at Pleiades Thomson X-Ray Source

NASA Astrophysics Data System (ADS)

Lim, J. K.; Rosenzweig, J. B.; Anderson, S. G.; Tremaine, A. M.

A recent development of the photo-cathode injector technology has greatly enhanced the beam quality necessary for the creation of high density/high brightness electron beam sources. In the Thomson backscattering x-ray experiment, there is an immense need for under 20 micron electron beam spot at the interaction point with a high-intensity laser in order to produce a large x-ray flux. This has been demonstrated successfully at PLEIADES in Lawrence Livermore National Laboratory. For this Thomson backscattering experiment, we employed an asymmetric triplet, high remanence permanent-magnet quads to produce smaller electron beams. Utilizing highly efficient optical transition radiation (OTR) beam spot imaging technique and varying electron focal spot sizes enabled a quadrupole scan at the interaction zone. Comparisons between Twiss parameters obtained upstream to those parameter values deduced from PMQ scan will be presented in this report.

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

Metallic interconnects for SOFC: Characterisation of corrosion resistance and conductivity evaluation at operating temperature of differently coated alloys

NASA Astrophysics Data System (ADS)

Fontana, S.; Amendola, R.; Chevalier, S.; Piccardo, P.; Caboche, G.; Viviani, M.; Molins, R.; Sennour, M.

One of challenges in improving the performance and cost-effectiveness of solid oxide fuel cells (SOFCs) is the development of suitable interconnect materials. Recent researches have enabled to decrease the operating temperature of the SOFC from 1000 to 800 °C. Chromia forming alloys are then among the best candidates for interconnects. However, low electronic conductivity and volatility of chromium oxide scale need to be solved to improve interconnect performances. In the field of high temperature oxidation of metals, it is well known that the addition of reactive element into alloys or as thin film coatings, improves their oxidation resistance at high temperature. The elements of beginning of the lanthanide group and yttrium are the most efficient. The goal of this study is to make reactive element oxides (La 2O 3, Nd 2O 3 and Y 2O 3) coatings by metal organic chemical vapour deposition (MOCVD) on Crofer 22 APU, AL 453 and Haynes 230 in order to form perovskite oxides which present a good conductivity at high temperature. The coatings were analysed after 100 h ageing at 800 °C in air under atmospheric pressure by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analyses, X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. Area-specific resistance (ASR) was measured in air for the same times and temperature, using a sandwich technique with Pt paste for electrical contacts between surfaces. The ASR values for the best coating were estimated to be limited to 0.035 Ω cm 2, even after 40,000 h use.

Fabricating the spherical and flake silver powder used for the optoelectronic devices

NASA Astrophysics Data System (ADS)

Ju, Wei; Ma, Wangjing; Zhang, Fangzhi; Chen, Yixiang; Xie, Jinpeng

2018-01-01

The spherical and flake silver powder with different particle size for the optoelectronic devices was partly prepared by using chemical reduction and ball milling method, and charactered by scanning electron microscope (SEM), X-ray diffraction (XRD), laser particle size analyzer and thermo-gravimetric(TG) analyzer. The particle size of three series of spherical silver powder fabricated by chemical reduction is about 1.5μm, 1μm and 0.6μm, respectively; after being mechanical milling, the particle size of flake silver powder with high flaky rate is about 10μm, 6μm and 2μm respectively. Thermo gravimetric (TG) and XRD analyses showed that the silver powders have high purity and crystalline, and then the laser particle size and SEM analyses showed that the silver powders has good uniformity.

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.

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.

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.

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

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.

Morphological reassessment and molecular phylogenetic analyses of Amauroderma s.lat. raised new perspectives in the generic classification of the Ganodermataceae family.

PubMed

Costa-Rezende, D H; Robledo, G L; Góes-Neto, A; Reck, M A; Crespo, E; Drechsler-Santos, E R

2017-12-01

Ganodermataceae is a remarkable group of polypore fungi, mainly characterized by particular double-walled basidiospores with a coloured endosporium ornamented with columns or crests, and a hyaline smooth exosporium. In order to establish an integrative morphological and molecular phylogenetic approach to clarify relationship of Neotropical Amauroderma s.lat. within the Ganodermataceae family, morphological analyses, including scanning electron microscopy, as well as a molecular phylogenetic approach based on one (ITS) and four loci (ITS-5.8S, LSU, TEF-1α and RPB1 ), were carried out. Ultrastructural analyses raised up a new character for Ganodermataceae systematics, i.e . , the presence of perforation in the exosporium with holes that are connected with hollow columns of the endosporium. This character is considered as a synapomorphy in Foraminispora , a new genus proposed here to accommodate Porothelium rugosum (≡ Amauroderma sprucei ). Furtadoa is proposed to accommodate species with monomitic context: F. biseptata, F. brasiliensis and F. corneri . Molecular phylogenetic analyses confirm that both genera grouped as strongly supported distinct lineages out of the Amauroderma s.str. clade.

Characterization of PCBs from computers and mobile phones, and the proposal of newly developed materials for substitution of gold, lead and arsenic.

PubMed

Dervišević, Irma; Minić, Duško; Kamberović, Željko; Ćosović, Vladan; Ristić, Mirjana

2013-06-01

In this paper, we have analyzed parts of printed circuit board (PCB) and liquid crystal display (LCD) screens of mobile phones and computers, quantitative and qualitative chemical compositions of individual components, and complete PCBs were determined. Differential thermal analysis (DTA) and differential scanning calorimetry (DSC) methods were used to determine the temperatures of phase transformations, whereas qualitative and quantitative compositions of the samples were determined by X-ray fluorescence spectrometry (XRF), inductively coupled plasma optical emission spectrometry (ICP-OES), and scanning electron microscopy (SEM)-energy dispersive X-ray spectrometry (EDS) analyses. The microstructure of samples was studied by optical microscopy. Based on results of the analysis, a procedure for recycling PCBs is proposed. The emphasis was on the effects that can be achieved in the recycling process by extraction of some parts before the melting process. In addition, newly developed materials can be an adequate substitute for some of the dangerous and harmful materials, such as lead and arsenic are proposed, which is in accordance with the European Union (EU) Restriction of the use of certain hazardous substances (RoHS) directive as well as some alternative materials for use in the electronics industry instead of gold and gold alloys.

The first description of eggs in the male reproductive system of Physaloptera bispiculata (Nematoda: Spiruroidaea).

PubMed

Oliveira-Menezes, A; Lanfredi-Rangel, A; Lanfredi, R M

2011-06-01

Physaloptera bispiculata (Nematoda: Spiruroidaea) is a parasite of Nectomys squamipes (Rodentia: Cricetidae), a water rat that only occurs in Brazil. Naturally infected rodents were captured in the municipality of Rio Bonito, Rio de Janeiro, Brazil. Adult P. bispiculata worms were collected, prepared and analysed by light and scanning electron microscopy. Under scanning electron microscopy, several eggs were seen glued by cement to the cloacal aperture. Light microscopy revealed that some male worms had an uncountable number of embryonated eggs in the ejaculatory duct, cloaca and also in the posterior portion of the intestine. The probable explanation is that the eggs developing in the female uterus are pumped by the female or sucked by the male to the cloacal opening and from this point to the intestine and ejaculatory duct. The male probably does not have the ability to expel the eggs and for this reason a large number were found in these organs. On the other hand, this could be an important adaptation for the parasite, i.e. male worms expelled by the host can carry a large number of eggs and spread them to intermediate hosts when ingested by these hosts. As far as we know this is the first record of a physalopterid nematode harbouring eggs in the cloacal region, ejaculatory duct or intestine.

Effect of the nanosized TiO2 particles in Pd/C catalysts as cathode materials in direct methanol fuel cells.

PubMed

Choi, Mahnsoo; Han, Choonsoo; Kim, In-Tae; Lee, Ji-Jung; Lee, Hong-Ki; Shim, Joongpyo

2011-07-01

Pd-TiO2/C catalysts were prepared by impregnating titanium dioxide (TiO2) on carbon-supported Pd (Pd/C) for use as the catalyst for the oxygen reduction reaction (ORR) in direct methanol fuel cells (DMFCs). Transmission electron microscope (TEM), scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses were carried to confirm the distribution, morphology and structure of Pd and TiO2 on the carbon support. In fuel cell test, we confirmed that the addition of TiO2 nanoparticles make the improved catalytic activity of oxygen reduction. The electrochemical characterization of the Pd-TiO2/C catalyst for the ORR was carried out by cyclic voltammetry (CV) in the voltage window of 0.04 V to 1.2 V with scan rate of 25 mV/s. With the increase in the crystallite size of TiO2, the peak potential for OH(ads) desorption on the surface of Pd particle shifted to higher potential. This implies that TiO2 might affect the adsorption and desorption of oxygen molecules on Pd catalyst. The performance of Pd-TiO2/C as a cathode material was found to be similar to or better performance than that of Pt/C.

Method to characterize inorganic particulates in lung tissue biopsies using field emission scanning electron microscopy

USGS Publications Warehouse

Lowers, Heather; Breit, George N.; Strand, Matthew; Pillers, Renee M.; Meeker, Gregory P.; Todorov, Todor I.; Plumlee, Geoffrey S.; Wolf, Ruth E.; Robinson, Maura; Parr, Jane; Miller, Robert J.; Groshong, Steve; Green, Francis; Rose, Cecile

2018-01-01

Humans accumulate large numbers of inorganic particles in their lungs over a lifetime. Whether this causes or contributes to debilitating disease over a normal lifespan depends on the type and concentration of the particles. We developed and tested a protocol for in situ characterization of the types and distribution of inorganic particles in biopsied lung tissue from three human groups using field emission scanning electron microscopy (FE-SEM) combined with energy dispersive spectroscopy (EDS). Many distinct particle types were recognized among the 13 000 particles analyzed. Silica, feldspars, clays, titanium dioxides, iron oxides and phosphates were the most common constituents in all samples. Particles were classified into three general groups: endogenous, which form naturally in the body; exogenic particles, natural earth materials; and anthropogenic particles, attributed to industrial sources. These in situ results were compared with those using conventional sodium hypochlorite tissue digestion and particle filtration. With the exception of clays and phosphates, the relative abundances of most common particle types were similar in both approaches. Nonetheless, the digestion/filtration method was determined to alter the texture and relative abundances of some particle types. SEM/EDS analysis of digestion filters could be automated in contrast to the more time intensive in situ analyses.

Hydrogen-enhanced cracking revealed by in situ micro-cantilever bending test inside environmental scanning electron microscope.

PubMed

Deng, Yun; Hajilou, Tarlan; Barnoush, Afrooz

2017-07-28

To evaluate the hydrogen (H)-induced embrittlement in iron aluminium intermetallics, especially the one with stoichiometric composition of 50 at.% Al, a novel in situ micro-cantilever bending test was applied within an environmental scanning electron microscope (ESEM), which provides both a full process monitoring and a clean, in situ H-charging condition. Two sets of cantilevers were analysed in this work: one set of un-notched cantilevers, and the other set with focused ion beam-milled notch laying on two crystallographic planes: (010) and (110). The cantilevers were tested under two environmental conditions: vacuum (approximately 5 × 10 -4  Pa) and ESEM (450 Pa water vapour). Crack initiation at stress-concentrated locations and propagation to cause catastrophic failure were observed when cantilevers were tested in the presence of H; while no cracking occurred when tested in vacuum. Both the bending strength for un-notched beams and the fracture toughness for notched beams were reduced under H exposure. The hydrogen embrittlement (HE) susceptibility was found to be orientation dependent: the (010) crystallographic plane was more fragile to HE than the (110) plane.This article is part of the themed issue 'The challenges of hydrogen and metals'. © 2017 The Author(s).

Probing the rhizosphere to define mineral organic relationships

NASA Astrophysics Data System (ADS)

Schulz, M. S.; Dohnalkova, A.; Stonestrom, D. A.

2016-12-01

Soil organic matter (SOM) accumulation and stabilization over time is an important process as soils are a large carbon reservoir in which feedbacks under changing climates are unclear. The association of SOM with poorly crystalline or short-range-ordered secondary minerals has been shown to be important for carbon stabilization. Commonly used soil extraction techniques display correlations of SOM with secondary phases but do not show causation. The fate of root exudates in soils and processes controlling exudate associations with mineral phases are as yet structurally undefined. Sub-micron exploration of in-situ relations provides valuable information on SOM-mineral interactions. Soils of the Santa Cruz (California) marine terrace chronosequence are used to illustrate changes in deep (> 1 m) rhizosphere through time. Cracks and soil ped faces are sites of high root density and organic matter (biofilm or mucilage) deposition. We employ a variety of scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) techniques for high resolution imaging and elemental analyses of deep rhizosphere and associated carbon mineral interactions. In these coastal prairie soils microscopy reveals secondary clay minerals associated with and possibly forming from organic-rich mucilage that occurs along the aforementioned rooting networks on fracture surfaces. We hypothesize that the production of secondary clays in the rhizosphere is an important mode of C incorporation into secondary minerals.

Synthesis and statistical modelling of dry sliding wear of Al 8011/6 vol.% AlB2 in situ composite

NASA Astrophysics Data System (ADS)

Kumar, Narendra; Singh, Sandeep Kumar; Gautam, Gaurav; Padap, Aditya Kumar; Mohan, Anita; Mohan, Sunil

2017-10-01

The present study has used response surface methodology (RSM) and central composite design (CCD) for modelling, using wear parameters to predict the wear performance of an Al 8011/6.0 vol.% AlB2 composite. The effect of applied load and sliding velocity was studied at five levels for a fixed sliding distance. To understand wear behaviour, sliding wear tests were planned according to CCD and performed on a pin-on-disc apparatus at ambient temperature. An analysis of variance (ANOVA) was conducted to show the relative significance of the parameters. A second-order regression model was developed to predict the wear loss and to establish the relationships between wear parameters. Response surface and contour plots were drawn to analyse the wear results. Worn surfaces were examined under scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS) was used to interpret the operative wear mechanisms. Validation tests results show good agreement between experimental and predicted data. As an initial step of this study, AlB2 particles were reinforced in Al 8011 alloy by an in situ technique to synthesise an Al 8011/6.0 vol.% AlB2 composite. During synthesis an in situ reaction takes place between molten alloy and inorganic salt KBF4 at 850 °C, which leads to the formation of AlB2 particles. The composite was analysed by x-ray diffractometer (XRD) to detect the phases present, while optical and scanning electron microscopy (OM & SEM) were carried out to ascertain morphology and particle distribution. Hardness was evaluated by a Vickers hardness testing machine.

Composition and microstructure of MTA and Aureoseal Plus: XRF, EDS, XRD and FESEM evaluation.

PubMed

Cianconi, L; Palopoli, P; Campanella, V; Mancini, M

2016-12-01

The aim of this study was to determine the chemical composition and the phases' microstructure of Aureoseal Plus (OGNA, Italy) and ProRoot MTA (Dentsply Tulsa Dental, USA) and to compare their characteristics. Study Design: Comparing Aureoseal Plus and ProRoot MTA microstructure by means of several analyses type. The chemical analysis of the two cements was assessed following the UNI EN ISO 196-2 norm. X-Ray fluorescence (XRF) was used to determine the element composition. The crystalline structure was analysed quantitatively using x-ray diffraction (XRD). Powders morphology was evaluated using a scanning electron microscope (SEM) with backscattering detectors, and a field emission scanning electron microscope (FESEM). Elemental analysis was performed by energy dispersive x-ray analysis (EDS). The semi-quantitative XRF analysis showed the presence of heavy metal oxides in both cements. The XRD spectra of the two cements reported the presence of dicalcium silicate, tricalcium silicate, tricalcium aluminate, tetracalcium aluminoferrite, bismuth oxide and gypsum. SEM analysis showed that ProRoot MTA powder is less coarse and more homogeneous than Aureoseal. Both powders are formed by particles of different shapes: round, prismatic and oblong. The EDS analysis showed that some ProRoot MTA particles, differently from Aureoseal, contain Ca, Si, Al and Fe. Oblong particles in ProRoot and Aureoseal are rich of bismuth. The strong interest in developing new Portland cement-based endodontic sealers will create materials with increased handling characteristics and physicochemical properties. A thorough investigation on two cement powders was carried out by using XRF, XRD, SEM and EDS analysis. To date there was a lack of studies on Aureoseal Plus. This cement is similar in composition to ProRoot MTA. Despite that it has distinctive elements that could improve its characteristics, resulting in a good alternative to MTA.

Ultrastructural properties of laser-irradiated and heat-treated dentin.

PubMed

Rohanizadeh, R; LeGeros, R Z; Fan, D; Jean, A; Daculsi, G

1999-12-01

Previous studies using scanning electron microscopy and infrared absorption spectroscopy reported that laser irradiation causes compositional changes in enamel. The purpose of this study was to evaluate the ultrastructural and compositional changes in dentin caused by irradiation with a short-pulse laser (Q-switched Nd:YAG). The irradiated and non-irradiated areas of the lased dentin samples were investigated by scanning (SEM) and transmission electron microscopy (TEM), micro-micro electron diffraction, and electron microprobe analysis of dispersive energy (EDX). Heat-treated dentin was similarly investigated. This study demonstrated that laser irradiation resulted in the recrystallization of dentin apatite and in the formation of additional calcium phosphate phases consisting of magnesium-substituted beta-tricalcium phosphate, beta-TCMP, beta-(Ca,Mg)3(PO4)2, and tetracalcium phosphate, TetCP, Ca4(PO4)O. TEM analyses of the modified and unmodified zones of the irradiated areas showed two types of crystal populations: much larger crystals from the modified zone and crystals with size and morphology similar to those of dentin apatite in the unmodified zone. The morphology of crystals in the modified zones in the irradiated dentin resembled those of dentin sintered at 800 or 950 degrees C. In the irradiated areas (modified and unmodified zones), the Ca/P ratio was lower compared with that in the non-irradiated dentin. The Mg/Ca ratio in the modified zones was higher than that in the unmodified zones and in the non-irradiated dentin. In sintered dentin, the Mg/Ca ratio increased as a function of sintering temperature. The ultrastructural and compositional changes observed in laser-irradiated dentin may be attributed to high temperature and high pressure induced by microplasma during laser irradiation. These changes may alter the solubility of the irradiated dentin, making it less susceptible to acid dissolution or to the caries process.

Mass and molecular composition of vesicular stomatitis virus: a scanning transmission electron microscopy analysis.

PubMed

Thomas, D; Newcomb, W W; Brown, J C; Wall, J S; Hainfeld, J F; Trus, B L; Steven, A C

1985-05-01

Dark-field scanning transmission electron microscopy was used to perform mass analyses of purified vesicular stomatitis virions, pronase-treated virions, and nucleocapsids, leading to a complete self-consistent account of the molecular composition of vesicular stomatitis virus. The masses obtained were 265.6 +/- 13.3 megadaltons (MDa) for the native virion, 197.5 +/- 8.4 MDa for the pronase-treated virion, and 69.4 +/- 4.9 MDa for the nucleocapsid. The reduction in mass effected by pronase treatment, which corresponds to excision of the external domains (spikes) of G protein, leads to an average of 1,205 molecules of G protein per virion. The nucleocapsid mass, after compensation for the RNA (3.7 MDa) and residual amounts of other proteins, yielded a complement of 1,258 copies of N protein. Calibration of the amounts of M, NS, and L proteins relative to N protein by biochemical quantitation yielded values of 1,826, 466, and 50 molecules, respectively, per virion. Assuming that the remaining virion mass is contributed by lipids in the viral envelope, we obtained a value of 56.1 MDa for its lipid content. In addition, four different electron microscopy procedures were applied to determine the nucleocapsid length, which we conclude to be 3.5 to 3.7 micron. The nucleocapsid comprises a strand of repeating units which have a center-to-center spacing of 3.3 nm as measured along the middle of the strand. We show that these repeating units represent monomers of N protein, each of which is associated with 9 +/- 1 bases of single-stranded RNA. From scanning transmission electron microscopy images of negatively stained nucleocapsids, we inferred that N protein has a wedge-shaped, bilobed structure with dimensions of approximately 9.0 nm (length), approximately 5.0 nm (depth), and approximately 3.3 nm (width, at the midpoint of its long axis). In the coiled configuration of the in situ nucleocapsid, the long axis of N protein is directed radially, and its depth corresponds to the pitch of the nucleocapsid helix.

Mass and molecular composition of vesicular stomatitis virus: a scanning transmission electron microscopy analysis.

PubMed Central

Thomas, D; Newcomb, W W; Brown, J C; Wall, J S; Hainfeld, J F; Trus, B L; Steven, A C

1985-01-01

Dark-field scanning transmission electron microscopy was used to perform mass analyses of purified vesicular stomatitis virions, pronase-treated virions, and nucleocapsids, leading to a complete self-consistent account of the molecular composition of vesicular stomatitis virus. The masses obtained were 265.6 +/- 13.3 megadaltons (MDa) for the native virion, 197.5 +/- 8.4 MDa for the pronase-treated virion, and 69.4 +/- 4.9 MDa for the nucleocapsid. The reduction in mass effected by pronase treatment, which corresponds to excision of the external domains (spikes) of G protein, leads to an average of 1,205 molecules of G protein per virion. The nucleocapsid mass, after compensation for the RNA (3.7 MDa) and residual amounts of other proteins, yielded a complement of 1,258 copies of N protein. Calibration of the amounts of M, NS, and L proteins relative to N protein by biochemical quantitation yielded values of 1,826, 466, and 50 molecules, respectively, per virion. Assuming that the remaining virion mass is contributed by lipids in the viral envelope, we obtained a value of 56.1 MDa for its lipid content. In addition, four different electron microscopy procedures were applied to determine the nucleocapsid length, which we conclude to be 3.5 to 3.7 micron. The nucleocapsid comprises a strand of repeating units which have a center-to-center spacing of 3.3 nm as measured along the middle of the strand. We show that these repeating units represent monomers of N protein, each of which is associated with 9 +/- 1 bases of single-stranded RNA. From scanning transmission electron microscopy images of negatively stained nucleocapsids, we inferred that N protein has a wedge-shaped, bilobed structure with dimensions of approximately 9.0 nm (length), approximately 5.0 nm (depth), and approximately 3.3 nm (width, at the midpoint of its long axis). In the coiled configuration of the in situ nucleocapsid, the long axis of N protein is directed radially, and its depth corresponds to the pitch of the nucleocapsid helix. Images PMID:2985822

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.

Routine postoperative CT-scans after burr hole trepanation for chronic subdural hematoma - better before or after drainage removal?

PubMed

Brokinkel, Benjamin; Ewelt, Christian; Holling, Markus; Hesselmann, Volker; Heindel, Walter Leonard; Stummer, Walter; Fischer, Bernhard Robert

2013-01-01

To evaluate timing of scheduled CT-scans after burr hole trepanation for chronic subdural hematoma (cSDH). 131 patients with primary cSDH were included. Scheduled CT-scans were performed after burr hole trepanation and placement of a subdural drain. The influence of CT-scanning with or without indwelling drain was analysed regarding subsequent surgery and CT-scans, duration of hospitalization, short- and middle-term follow up by single factor analyses. Subgroup analyses were performed for patients receiving anticoagulant drugs. Median age was 74 years. Routine CT-scans with indwelling drainage were not shown to be beneficial regarding subsequent burr hole trepanations (p=0.243), craniotomies (p=1.000) and outcome at discharge (p=0.297). Mean duration of hospitalization (11 vs. 8 days, p=0.013) was significantly longer and number of subsequent CT-scans was higher when CT scan was performed with indwelling drain (2.3 vs. 1.4, p=0.001). In middle-term follow-up, beneficial effects of CT-scanning with inlaying drainage could neither be shown. Moreover, advantageous effects of CT-scans with indwelling drains could neither be shown for patients receiving anticoagulant drugs. Scheduled postoperative cranial imaging with indwelling drains was not shown to be beneficial and misses information of intracranial damage inflicted by removal of drains. We thus recommend CT-scanning after drainage removal.

Facile synthesis of 3D few-layered MoS2 coated TiO2 nanosheet core-shell nanostructures for stable and high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Chen, Biao; Zhao, Naiqin; Guo, Lichao; He, Fang; Shi, Chunsheng; He, Chunnian; Li, Jiajun; Liu, Enzuo

2015-07-01

Uniform transition metal sulfide deposition on a smooth TiO2 surface to form a coating structure is a well-known challenge, caused mainly due to their poor affinities. Herein, we report a facile strategy for fabricating mesoporous 3D few-layered (<4 layers) MoS2 coated TiO2 nanosheet core-shell nanocomposites (denoted as 3D FL-MoS2@TiO2) by a novel two-step method using a smooth TiO2 nanosheet as a template and glucose as a binder. The core-shell structure has been systematically examined and corroborated by transmission electron microscopy, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. It is found that the resultant 3D FL-MoS2@TiO2 as a lithium-ion battery anode delivers an outstanding high-rate capability with an excellent cycling performance, relating to the unique structure of 3D FL-MoS2@TiO2. The 3D uniform coverage of few-layered (<4 layers) MoS2 onto the TiO2 can remarkably enhance the structure stability and effectively shortens the transfer paths of both lithium ions and electrons, while the strong synergistic effect between MoS2 and TiO2 can significantly facilitate the transport of ions and electrons across the interfaces, especially in the high-rate charge-discharge process. Moreover, the facile fabrication strategy can be easily extended to design other oxide/carbon-sulfide/oxide core-shell materials for extensive applications.Uniform transition metal sulfide deposition on a smooth TiO2 surface to form a coating structure is a well-known challenge, caused mainly due to their poor affinities. Herein, we report a facile strategy for fabricating mesoporous 3D few-layered (<4 layers) MoS2 coated TiO2 nanosheet core-shell nanocomposites (denoted as 3D FL-MoS2@TiO2) by a novel two-step method using a smooth TiO2 nanosheet as a template and glucose as a binder. The core-shell structure has been systematically examined and corroborated by transmission electron microscopy, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. It is found that the resultant 3D FL-MoS2@TiO2 as a lithium-ion battery anode delivers an outstanding high-rate capability with an excellent cycling performance, relating to the unique structure of 3D FL-MoS2@TiO2. The 3D uniform coverage of few-layered (<4 layers) MoS2 onto the TiO2 can remarkably enhance the structure stability and effectively shortens the transfer paths of both lithium ions and electrons, while the strong synergistic effect between MoS2 and TiO2 can significantly facilitate the transport of ions and electrons across the interfaces, especially in the high-rate charge-discharge process. Moreover, the facile fabrication strategy can be easily extended to design other oxide/carbon-sulfide/oxide core-shell materials for extensive applications. Electronic supplementary information (ESI) available: Supplementary SEM, TEM, XPS and EIS analyses. See DOI: 10.1039/c5nr03334a

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.

Assets and pitfalls of chemical and microscopic analyses on gunshot residues in skeletonized bodies: a report of five cases.

PubMed

Amadasi, Alberto; Gibelli, Daniele; Mazzarelli, Debora; Porta, Davide; Gaudio, Daniel; Salsarola, Dominic; Brandone, Alberto; Rizzi, Agostino; Cattaneo, Cristina

2015-07-01

In case of gunshot wounds, forensic anthropologists and pathologists have many tools at hand, and the assistance that chemical and microscopic investigations can provide in such scenarios is often valuable and crucial. However, the results of such analyses in the search of gunshot residues (GSR) ought not to be acritically considered. We report five cases where chemical (sodium rhodizonate) and microscopic (scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX)) analyses were performed for the search of GSR. Four cases concerned the forensic field and analyses on buried, charred, or submerged remains, whereas one case concerned the historical remains of a soldier of the First World War. In every case, the search for GSR with these techniques showed their persistence even after long periods and preservation in peculiar environments. However, chemical analyses provided their contribution, but in two cases, anthropological analyses provided crucial and solving results. The five cases show the indisputable usefulness of chemical and microscopic analyses in the search of GSR in gunshot wounds and especially how such residues may survive in time and in adverse environmental conditions. However, experts should always be dubious about some pitfalls (such as contamination) one can frequently find in these scenarios.

Full in-vitro analyses of new-generation bulk fill dental composites cured by halogen light.

PubMed

Tekin, Tuçe Hazal; Kantürk Figen, Aysel; Yılmaz Atalı, Pınar; Coşkuner Filiz, Bilge; Pişkin, Mehmet Burçin

2017-08-01

The objective of this study was to investigate the full in-vitro analyses of new-generation bulk-fill dental composites cured by halogen light (HLG). Two types' four composites were studied: Surefill SDR (SDR) and Xtra Base (XB) as bulk-fill flowable materials; QuixFill (QF) and XtraFill (XF) as packable bulk-fill materials. Samples were prepared for each analysis and test by applying the same procedure, but with different diameters and thicknesses appropriate to the analysis and test requirements. Thermal properties were determined by thermogravimetric analysis (TG/DTG) and differential scanning calorimetry (DSC) analysis; the Vickers microhardness (VHN) was measured after 1, 7, 15 and 30days of storage in water. The degree of conversion values for the materials (DC, %) were immediately measured using near-infrared spectroscopy (FT-IR). The surface morphology of the composites was investigated by scanning electron microscopes (SEM) and atomic-force microscopy (AFM) analyses. The sorption and solubility measurements were also performed after 1, 7, 15 and 30days of storage in water. In addition to his, the data were statistically analyzed using one-way analysis of variance, and both the Newman Keuls and Tukey multiple comparison tests. The statistical significance level was established at p<0.05. According to the ISO 4049 standards, all the tested materials showed acceptable water sorption and solubility, and a halogen light source was an option to polymerize bulk-fill, resin-based dental composites. Copyright © 2017 Elsevier B.V. All rights reserved.

Validation of cell-free culture using scanning electron microscopy (SEM) and gene expression studies.

PubMed

Yang, R; Elankumaran, Y; Hijjawi, N; Ryan, U

2015-06-01

A cell-free culture system for Cryptosporidium parvum was analysed using scanning electron microscopy (SEM) to characterise life cycle stages and compare gene expression in cell-free culture and cell culture using HCT-8 cells. Cryptosporidium parvum samples were harvested at 2 h, 8 h, 14 h, 26 h, 50 h, 74 h, 98 h, 122 h and 170 h, chemically fixed and specimens were observed using a Zeiss 1555 scanning electron microscope. The presence of sporozoites, trophozoites and type I merozoites were identified by SEM. Gene expression in cell culture and cell-free culture was studied using reverse transcriptase quantitative PCR (RT-qPCR) of the sporozoite surface antigen protein (cp15), the glycoprotein 900 (gp900), the Cryptosporidium oocyst wall protein (COWP) and 18S ribosomal RNA (rRNA) genes in both cell free and conventional cell culture. In cell culture, cp15 expression peaked at 74 h, gp900 expression peaked at 74 h and 98 h and COWP expression peaked at 50 h. In cell-free culture, CP15 expression peaked at 98 h, gp900 expression peaked at 74 h and COWP expression peaked at 122 h. The present study is the first to compare gene expression of C. parvum in cell culture and cell-free culture and to characterise life cycle stages of C. parvum in cell-free culture using SEM. Findings from this study showed that gene expression patterns in cell culture and cell-free culture were similar but in cell-free culture, gene expression was delayed for CP15 and COWP in cell free culture compared with the cell culture system and was lower. Although three life cycle stageswere conclusively identified, improvements in SEM methodology should lead to the detection of more life cycle stages. Copyright © 2015 Elsevier Inc. All rights reserved.

Magneto-optical properties of BaCryFe12-yO19 (0.0 ≤ y ≤ 1.0) hexaferrites

NASA Astrophysics Data System (ADS)

Asiri, S.; Güner, S.; Korkmaz, A. D.; Amir, Md.; Batoo, K. M.; Almessiere, M. A.; Gungunes, H.; Sözeri, H.; Baykal, A.

2018-04-01

In this study, nanocrystalline BaCryFe12-yO19 (0.0 ≤ y ≤ 1.0) hexaferrite powders were prepared by sol-gel auto combustion method and the effect of Cr3+ ion substitution on morphology, structure, optic and magnetic properties of Barium hexaferrite were investigated. X-ray powder diffraction (XRD) analyses confirmed the purity of all samples. The XRD data shows that the average crystallite size lies between 60.95 nm and 50.10 nm and same was confirmed by Transmission electron microscopy. Transmission electron and scanning electron microscopy analyses presented the hexagonal morphology of all products. The characteristic hysteresis (σ-H) curves proved the ferromagnetic feature of as grown nanoparticle samples. Specific saturation magnetization (σs) drops from 46.59 to 34.89 emu/g with increasing Cr content while the coercive field values lie between 770 and 1652 Oe. The large magnitude of the magnetocrystalline (intrinsic) anisotropy field, (Ha) between 11.0 and 12.6 kOe proves that all products are magnetically hard. The energy band gap values decrease from 2.0 eV to 1.84 eV with increasing Cr content. From 57Fe Mössbauer spectroscopy, the variation in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values were determined and discussed.

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

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.

Polyethylene Films Containing Silver Nanoparticles for Applications in Food Packaging: Characterization of Physico-Chemical and Anti-Microbial Properties.

PubMed

Becaro, Aline A; Puti, Fernanda C; Correa, Daniel S; Paris, Elaine C; Marconcini, José M; Ferreira, Marcos D

2015-03-01

This paper reports the antibacterial effect and physico-chemical characterization of films containing silver nanoparticles for use as food packaging. Two masterbatches (named PEN and PEC) con- taining silver nanoparticles embedded in distinct carriers (silica and titanium dioxide) were mixed with low-density polyethylene (LDPE) in different compositions and extruded to produce plain films. These films were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). The morphology of the films showed the formation of agglomerates of nanoparticles in both PEN and PEC composites. X-ray analyses confirmed the presence of SiO2 in PEN samples and TiO2 in PEC samples. Thermal analyses indicated an increase in thermal stability of the PEC compositions. The antimicrobial efficacy was determined by applying the test strain for Escherichia coli and Staphylococcus aureus, according to the Japanese Industrial Standard Method (JIS Z 2801:2000). The films analyzed showed antimicrobial properties against the tested microorganisms, presenting better activity against the S. aureus than E. Coli. These findings suggest that LDPE films with silver nanoparticles are promising to provide a significant contribution to the quality and safety of packaged food.

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.

The oxidative corrosion of carbide inclusions at the surface of uranium metal during exposure to water vapour.

PubMed

Scott, T B; Petherbridge, J R; Harker, N J; Ball, R J; Heard, P J; Glascott, J; Allen, G C

2011-11-15

The reaction between uranium and water vapour has been well investigated, however discrepancies exist between the described kinetic laws, pressure dependence of the reaction rate constant and activation energies. Here this problem is looked at by examining the influence of impurities in the form of carbide inclusions on the reaction. Samples of uranium containing 600 ppm carbon were analysed during and after exposure to water vapour at 19 mbar pressure, in an environmental scanning electron microscope (ESEM) system. After water exposure, samples were analysed using secondary ion mass spectrometry (SIMS), focused ion beam (FIB) imaging and sectioning and transmission electron microscopy (TEM) with X-ray diffraction (micro-XRD). The results of the current study indicate that carbide particles on the surface of uranium readily react with water vapour to form voluminous UO(3) · xH(2)O growths at rates significantly faster than that of the metal. The observation may also have implications for previous experimental studies of uranium-water interactions, where the presence of differing levels of undetected carbide may partly account for the discrepancies observed between datasets. Crown Copyright © 2011. Published by Elsevier B.V. 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.

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.

Carbon contamination in scanning transmission electron microscopy and its impact on phase-plate applications.

PubMed

Hettler, Simon; Dries, Manuel; Hermann, Peter; Obermair, Martin; Gerthsen, Dagmar; Malac, Marek

2017-05-01

We analyze electron-beam induced carbon contamination in a transmission electron microscope. The study is performed on thin films potentially suitable as phase plates for phase-contrast transmission electron microscopy. Electron energy-loss spectroscopy and phase-plate imaging is utilized to analyze the contamination. The deposited contamination layer is identified as a graphitic carbon layer which is not prone to electrostatic charging whereas a non-conductive underlying substrate charges. Several methods that inhibit contamination are evaluated and the impact of carbon contamination on phase-plate imaging is discussed. The findings are in general interesting for scanning transmission electron microscopy applications. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

New method for revealing dislocations in garnet: premelting decoration

NASA Astrophysics Data System (ADS)

Liu, Xiangwen; Xie, Zhanjun; Jin, Zhenmin; Li, Zhuoyue; Ao, Ping; Wu, Yikun

2018-05-01

Premelting decoration (PMD) of dislocation experiments was carried out on garnets at 1 atmosphere pressure and temperatures of 800-1000 °C. Numerous decorated lines were observed on the polished surface of heat-treated garnet grains. The results of scanning electron microscopy, laser Raman spectroscopy and transmission electron microscopy (TEM) analyses indicate that these decorated lines were generated by premelting reaction along the dislocation lines and subgrain boundaries. The constituents of decorated lines on the polished surface of garnet are hematite, magnetite, and melt. While, in the interior of garnet, their constituents changed to Al-bearing magnetite and melt. The dislocation density of a gem-quality megacrystal garnet grain by means of the PMD is similar to that obtained by TEM, which confirms that the PMD is a new reliable method for revealing dislocations in garnet. This method greatly reduces the cost and time involved in the observation of dislocation microstructures in deformed garnet.

Structural-dependent thermal conductivity of aluminium nitride produced by reactive direct current magnetron sputtering

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

Belkerk, B. E.; Soussou, A.; Carette, M.

This Letter reports the thermal conductivity of aluminium nitride (AlN) thin-films deposited by reactive DC magnetron sputtering on single-crystal silicon substrates (100) with varying plasma and magnetic conditions achieving different crystalline qualities. The thermal conductivity of the films was measured at room temperature with the transient hot-strip technique for film thicknesses ranging from 100 nm to 4000 nm. The thermal conductivity was found to increase with the thickness depending on the synthesis conditions and film microstructure. The conductivity in the bulk region of the films, so-called intrinsic conductivity, and the boundary resistance were in the range [120-210] W m{sup -1}more » K{sup -1} and [2-30 Multiplication-Sign 10{sup -9}] K m{sup 2} W{sup -1}, respectively, in good agreement with microstructures analysed by x-ray diffraction, high-resolution-scanning-electron-microscopy, and transmission-electron-microscopy.« less

Precipitation hardening behaviour of Al-Mg-Si alloy processed by cryorolling and room temperature rolling

NASA Astrophysics Data System (ADS)

Hussain, Maruff; Nageswara rao, P.; Singh, Dharmendra; Jayaganthan, R.

2018-04-01

The precipitation hardenable aluminium alloy (Al-Mg-Si) plates were solutionized and subjected to rolling at room temperature and liquid nitrogen temperature (RTR, CR) up to a true strain of ∼2.7. The rolled sheets were uniformly aged at room temperature and above room temperature (125 °C) to induce precipitation. The rolled and aged samples were analysed using differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), hardness and tensile tests. The strength and ductility were simultaneously improved after controlled ageing of the cryorolled (CR) and room temperature rolled (RTR) samples. However, the increment in strength is more in RTR material than CR material with same ductility. Transmission electron microscopy analysis revealed the formation of ultrafine grains (UFG) filled with dislocations and nanosized precipitates in the CR and RTR conditions after ageing treatment. The behaviour of CR and RTR alloy is same under natural ageing conditions.

Microchondrule-bearing clast in the Piancaldoli LL3 meteorite - A new kind of type 3 chondrite and its relevance to the history of chondrules

NASA Technical Reports Server (NTRS)

Rubin, A. E.; Scott, E. R. D.; Keil, K.

1982-01-01

Electron microprobe, scanning electron microscope, and petrographic analyses of the microchondritic clast of the Piancaldoli LL3 chondrite are reported and compared with other type three chondrites. The clast, like other type three chondrites, has a fine-grained Fe-rich opaque silicate matrix, sharply defined chondrules, abundant low-Ca clinopyroxene and minor troilite and Si and Cr-bearing metallic Fe, Ni. However, the very high model matrix abundance, unique characteristics of the chondrules, and absence of microscopically observable olivine indicate that the clast is a new type of type three chondrite. It is concluded that the microchondrules were formed by the same process that formed normal-sized chondrules in type three chondrites: melting of preexisting dustballs. It is suggested that dust grains were mineralogically sorted in the nebula before aggregating into dustballs.

Evaluation of in-situ deformation experiments of TRIP steel

NASA Astrophysics Data System (ADS)

Procházka, J.; Kučerová, L.; Bystrianský, M.

2017-02-01

The paper reports on the behaviour of low alloyed TRIP (transformation induced plasticity) steel with Niobium during tensile test. The structures were analysed using in-situ tensile testing coupled with electron backscattering diffraction (EBSD) analysis carried out in scanning electron microscope (SEM). Steel specimens were of same chemical composition; however three different annealing temperatures, 800 °C, 850 °C and 950 °C, were applied to the material during the heat treatment. The treatment consisted of annealing for 20 minutes in the furnace; cooling in salt bath after the heating and holding at 425 °C for 20 minutes for all the samples. Untreated bar was used as reference material. Flat samples for deformation stage were cut out of the heat-treated bars. In situ documentation of microstructure and crystallography development were carried out during the deformation experiments. High deformation lead to significant degradation of EBSD signal.

Effects of Piezoelectric Potential of ZnO on Resistive Switching Characteristics of Flexible ZnO/TiO2 Heterojunction Cells

NASA Astrophysics Data System (ADS)

Li, Hongxia; Zhou, You; Du, Gang; Huang, Yanwei; Ji, Zhenguo

2018-03-01

Flexible resistance random access memory (ReRAM) devices with a heterojunction structure of PET/ITO/ZnO/TiO2/Au were fabricated on polyethylene terephthalate/indium tin oxide (PET/ITO) substrates by different physical and chemical preparation methods. X-ray diffraction, scanning electron microscopy and atomic force microscopy were carried out to investigate the crystal structure, surface topography and cross-sectional structure of the prepared films. X-ray photoelectron spectroscopy was also used to identify the chemical state of Ti, O and Zn elements. Theoretical and experimental analyses were conducted to identify the effect of piezoelectric potential of ZnO on resistive switching characteristics of flexible ZnO/TiO2 heterojunction cells. The results showed a pathway to enhance the performance of ReRAM devices by engineering the interface barrier, which is also feasible for other electronics, optoelectronics and photovoltaic devices.

Metallurgical and Mechanical Evaluation of 4340 Steel Produced by Direct Metal Laser Sintering

NASA Astrophysics Data System (ADS)

Jelis, Elias; Clemente, Matthew; Kerwien, Stacey; Ravindra, Nuggehalli M.; Hespos, Michael R.

2015-03-01

Direct metal laser sintering (DMLS) was used to produce high-strength low-alloy 4340 steel specimens. Mechanical and metallurgical analyses were performed on the specimens to determine the samples with the highest strengths and the least porosity. The optimal process parameters were thus defined based on the corresponding experimental conditions. Additionally, the effects of fabricating specimens with both virgin and recycled powders were studied. Scanning electron microscopy and electron-dispersive spectroscopy were performed on both types of powders to determine the starting morphology and composition. The initial tensile results are promising, suggesting that DMLS can produce specimens equal in strength to wrought materials. However, there is evidence of cracking on several of the heat-treated tensile specimens that is unexplained. Several theories point to disturbances in the build chamber environment that went undetected while the specimens were being fabricated.

A facile synthesis of zinc oxide/multiwalled carbon nanotube nanocomposite lithium ion battery anodes by sol-gel method

NASA Astrophysics Data System (ADS)

Köse, Hilal; Karaal, Şeyma; Aydın, Ali Osman; Akbulut, Hatem

2015-11-01

Free standing zinc oxide (ZnO) and multiwalled carbon nanotube (MWCNT) nanocomposite materials are prepared by a sol gel technique giving a new high capacity anode material for lithium ion batteries. Free-standing ZnO/MWCNT nanocomposite anodes with two different chelating agent additives, triethanolamine (TEA) and glycerin (GLY), yield different electrochemical performances. Field emission gun scanning electron microscopy (FEG-SEM), energy dispersive X-ray spectrometer (EDS), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) analyses reveal the produced anode electrodes exhibit a unique structure of ZnO coating on the MWCNT surfaces. Li-ion cell assembly using a ZnO/MWCNT/GLY free-standing anode and Li metal cathode possesses the best discharge capacity, remaining as high as 460 mAh g-1 after 100 cycles. This core-shell structured anode can offer increased energy storage and performance over conventional anodes in Li-ion batteries.

Xenoliths in the CM2 Carbonaceous Chondrite LON 94101: Implications for Complex Mixing on the Asteroidal Parent Body

NASA Technical Reports Server (NTRS)

Lindgren, P.; Lee, M. R.; Sofe, M.; Zolensky, M. E.

2011-01-01

Xenoliths are foreign clasts that oc-cur in various classes of meteorites, e.g. [1,2,3]. A re-cent study reveals the presence of several distinct classes of xenoliths in regolith-bearing meteorites, in-cluding in over 20 different carbonaceous chondrites [4]. The most common types of xenoliths are fine-grained hydrous clasts, often referred to as C1 or CI clasts in the literature, although their mineralogy is actually more similar to hydrous micrometeorites [5,6]. Xenoliths in meteorites present an opportunity to study material not yet classified or available as separate meteorites, and can provide additional information on processes in the dynamic early history of the Solar Sys-tem. Here we have performed chemical and mineralogi-cal analyses of xenoliths in the CM2 carbonaceous chondrite LON 94101, using scanning electron micro-scopy (SEM) and transmission electron microscopy (TEM).

Nano-crystalline hydroxyapatite bio-mineral for the treatment of strontium from aqueous solutions.

PubMed

Handley-Sidhu, Stephanie; Renshaw, Joanna C; Yong, Ping; Kerley, Robert; Macaskie, Lynne E

2011-01-01

Hydroxyapatites were analysed using electron microscopy, X-ray diffraction (XRD) and X-ray fluorescence (XRF) analysis. Examination of a bacterially produced hydroxyapatite (Bio-HA) by scanning electron microscopy showed agglomerated nano-sized particles; XRD analysis confirmed that the Bio-HA was hydroxyapatite, with an organic matter content of 7.6%; XRF analysis gave a Ca/P ratio of 1.55, also indicative of HA. The size of the Bio-HA crystals was calculated as ~25 nm from XRD data using the Scherrer equation, whereas Comm-HA powder size was measured as ≤ 50 μm. The nano-crystalline Bio-HA was ~7 times more efficient in removing Sr(2+) from synthetic groundwater than Comm-HA. Dissolution of HA as indicated by the release of phosphate into the solution phase was higher in the Comm-HA than the Bio-HA, indicating a more stable biomaterial which has a potential for the remediation of contaminated sites.

Incorporation of the zosteric sodium salt in silica nanocapsules: synthesis and characterization of new fillers for antifouling coatings

NASA Astrophysics Data System (ADS)

Ruggiero, Ludovica; Crociani, Laura; Zendri, Elisabetta; El Habra, Naida; Guerriero, Paolo

2018-05-01

In the last decade many commercial biocides were gradually banned for toxicity. This work reports, for the first time, the synthesis and characterization of silica nanocontainers loaded with a natural product antifoulant (NPA), the zosteric sodium salt which is a non-commercial and environmentally friendly product with natural origin. The synthesis approach is a single step dynamic self-assembly with tetraethoxysilane (TEOS) as silica precursor. Unlike conventional mesoporous silica nanoparticles, the structure of these silica nanocontainers provides loading capacity and allows prolonged release of biocide species. The obtained nanocapsules have been characterized morphologically by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The encapsulation was checked by FTIR ATR spectroscopy and thermogravimetric analyses. The results of the release studies show the great potential of the here presented newly developed nanofillers in all applications where a controlled release of non-toxic and environmentally friendly biocides is required.

Laser-induced periodic surface structures formation on mesoporous silicon from nanoparticles produced by picosecond and femtosecond laser shots

NASA Astrophysics Data System (ADS)

Talbi, Abderazek; Kaya-Boussougou, Sostaine; Sauldubois, Audrey; Stolz, Arnaud; Boulmer-Leborgne, Chantal; Semmar, Nadjib

2017-07-01

This paper deals with the formation of laser-induced periodic surface structures (LIPSS) on mesoporous silicon thin films induced by two laser regimes in the UV range: picosecond and femtosecond. Different LIPSS formation mechanisms from nanoparticles, mainly coalescence and agglomeration, have been evidenced by scanning electron microscopy analysis. The apparition of a liquid phase during both laser interaction at low fluence (20 mJ/cm2) and after a large number of laser pulses (up to 12,000) has been also shown with 100 nm size through incubation effect. Transmission electron microscopy analyses have been conducted to investigate the molten phase structures below and inside LIPSS. Finally, it has shown that LIPSS are composed of amorphous silicon when mesoporous silicon is irradiated by laser beam in both regimes. Nevertheless, mesoporous silicon located between LIPSS stays crystallized.

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.

Enhanced photocatalytic activity of ZnO/CuO nanocomposite for the degradation of textile dye on visible light illumination.

PubMed

Saravanan, R; Karthikeyan, S; Gupta, V K; Sekaran, G; Narayanan, V; Stephen, A

2013-01-01

The photocatalytic degradation of organic dyes such as methylene blue and methyl orange in the presence of various percentages of composite catalyst under visible light irradiation was carried out. The catalyst ZnO nanorods and ZnO/CuO nanocomposites of different weight ratios were prepared by new thermal decomposition method, which is simple and cost effective. The prepared catalysts were characterized by different techniques such as X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and UV-visible absorption spectroscopy. Further, the most photocatalytically active composite material was used for degradation of real textile waste water under visible light illumination. The irradiated samples were analysed by total organic carbon and chemical oxygen demand. The efficiency of the catalyst and their photocatalytic mechanism has been discussed in detail. Copyright © 2012 Elsevier B.V. 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.

Control of microbiological corrosion on carbon steel with sodium hypochlorite and biopolymer.

PubMed

Oliveira, Sara H; Lima, Maria Alice G A; França, Francisca P; Vieira, Magda R S; Silva, Pulkra; Urtiga Filho, Severino L

2016-07-01

In the present work, the interaction of a mixture of a biocide, sodium hypochlorite (NaClO), and a biopolymer, xanthan, with carbon steel coupons exposed to seawater in a turbulent flow regime was studied. The cell concentrations, corrosion rates, biomasses, and exopolysaccharides (EPSs) produced on the coupon surfaces with the various treatments were quantified. The corrosion products were evaluated using X-ray diffraction (XRD), and the surfaces of steels were analysed by scanning electron microscopy (SEM). The results indicated that xanthan and the hypochlorite-xanthan mixture reduced the corrosion rate of steel. Copyright © 2016. Published by Elsevier B.V.

Polymethacrylic acid as a new precursor of CuO nanoparticles

NASA Astrophysics Data System (ADS)

Hosny, Nasser Mohammed; Zoromba, Mohamed Shafick

2012-11-01

Polymethacrylic acid and its copper complexes have been synthesized and characterized. These complexes have been used as precursors to produce CuO nanoparticles by thermal decomposition in air. The stages of decompositions and the calcination temperature of the precursors have been determined from thermal analyses (TGA). The obtained CuO nanoparticles have been characterized by X-ray diffraction (XRD), scanning tunneling microscopy (STM) and transmission electron microscopy (TEM). XRD showed a monoclinic structure with particle size 8-20 nm for the synthesized copper oxide nanoparticles. These nanoparticles are catalytically active in decomposing hydrogen peroxide and a mechanism of decomposition has been suggested.

Axenic isolation of viable Giardia muris trophozoites.

PubMed

Tillotson, K D; Buret, A; Olson, M E

1991-06-01

Large numbers of viable Giardia muris trophozoites were isolated from the duodenum of experimentally infected mice 6 days after inoculation with 1,000 G. muris cysts. A series of shaking, incubation, and washing steps in the presence of the broad-spectrum antibiotic piperacillin readily provided 4.9 +/- 1.5 x 10(5) G. muris trophozoites per mouse, free of detectable contaminant organisms. Anaerobic and microaerophilic culturing and scanning electron microscopy demonstrated axenic status and high purity of the isolates. The viability of trophozoites was 98 +/- 2%. Application of this technique should permit novel immunological and epidemiological analyses of G. muris infection and biochemical investigations of this protozoan parasite.

Morphology and petrography of volcanic ashes.

NASA Technical Reports Server (NTRS)

Heiken, G.

1972-01-01

Study of volcanic ash samples collected from a variety of recent eruptions using petrography, chemical analyses, and scanning electron microscopy to characterize each type and to relate ash morphology to magma composition and the type of eruption. The ashes are placed in the broad genetic categories of magmatic and phreatomagmatic. The morphology of ash particles from magmatic eruptions of high viscosity magma is governed primarily by vesicle density and shape. Ash particles from eruptions of low viscosity magmas are mostly droplets. The morphology of ash particles from phreatomagmatic eruptions is controlled by stresses within the chilled magma which result in fragmentation of the glass to form small blocky or pyramidal glass ash particles.

Biosorption of lead by citrobacter freundii immobilized on hazelnut shells

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

Bueyuekguengoer, H.; Wilk, M.; Schubert, H.

1996-12-31

Biosorption of lead from aqueous solutions by living and immobilized cell of C. freundii was examined as a function of metal concentration in a batch laboratory bioreactor. Lead concentrations were analyzed using Atomic Absorption Spectrophotometer (AAS). X-ray Energy Dispersion (EDX) analyses were made in order to determine the accumulation of lead on the cells and shell surfaces. Before and after the experiments the biomaterials and adsorbents were examined by Scanning Electron Microscopy (SEM). Biosorption was detected over a range of initial lead concentrations from 25{times}10{sup -3} to 200{times}10{sup -3} kg/m{sup 3}. 15 refs., 4 figs.

Failure Surface Analysis of Polyimide/Titanium Notched Coating Adhesion Specimens

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

GIUNTA,RACHEL K.; KANDER,RONALD G.

2000-12-18

Adhesively bonded joints of LaRC{trademark} PETI-5, a phenylethynyl-terminated polyimide, with chromic acid anodized titanium were fabricated and debonded interfacially. The adhesive-substrate failure surfaces were investigated using several surface analysis techniques. From Auger spectroscopy, field emission scanning electron microscopy, and atomic force microscopy studies, polymer appears to be penetrating the pores of the anodized substrate to a depth of approximately 100 nm. From x-ray photoelectron spectroscopy data, the polymer penetrating the pores appears to be in electrical contact with the titanium substrate, leading to differential charging. These analyses confirm that the polymer is becoming mechanically interlocked within the substrate surface.

Dujardinascaris gigantea sp. n. (Nematoda: Ascaridida) from the critically endangered crocodile Alligator sinensis Fauvel (Reptilia: Crocodylia).

PubMed

Zhao, Jin-Hong; Li, Liang; Guo, Yan-Ning; Zhang, Lu-Ping

2015-03-01

The Chinese alligator Alligator sinensis Fauvel (Reptilia: Crocodylia) is considered as one of the most critically endangered species of the 23 extant crocodiles. However, our knowledge of the helminth parasites of this rare animal is completely lacking. During a helminthological survey of reptiles in China, we found a new ascaridoid nematode, Dujardinascaris gigantea sp. n. from A. sinensis. The morphology of D. gigantea sp. n. was studied using light and scanning electron microscopy. The new species was also characterised using molecular methods by sequencing and analysing the small ribosomal DNA (18S) and the second internal transcribed spacer (ITS-2).

Surface Functionalization of Diamond Films by Photoreaction of Elemental Sulfur and Their Surface Properties

NASA Astrophysics Data System (ADS)

Nakamura, Takako; Ohana, Tsuguyori

2012-08-01

A useful method for direct sulfurization of diamond film surfaces by photoreaction of elemental sulfur was developed. The introduction of thiol groups onto the diamond films was confirmed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and scanning electron microscopy (SEM) analyses. The sulfur-modified diamond films attached to gold nanoparticles by self-assembly. The degrees of thiol group introduction and gold attachment were found to depend on photoirradiation time by monitoring by XPS. The gold-modified diamond film was observed to act as a surface-enhanced Raman scattering substrate for measurement of picric acid.

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

Vibrational spectroscopy in the electron microscope.

PubMed

Krivanek, Ondrej L; Lovejoy, Tracy C; Dellby, Niklas; Aoki, Toshihiro; Carpenter, R W; Rez, Peter; Soignard, Emmanuel; Zhu, Jiangtao; Batson, Philip E; Lagos, Maureen J; Egerton, Ray F; Crozier, Peter A

2014-10-09

Vibrational spectroscopies using infrared radiation, Raman scattering, neutrons, low-energy electrons and inelastic electron tunnelling are powerful techniques that can analyse bonding arrangements, identify chemical compounds and probe many other important properties of materials. The spatial resolution of these spectroscopies is typically one micrometre or more, although it can reach a few tens of nanometres or even a few ångströms when enhanced by the presence of a sharp metallic tip. If vibrational spectroscopy could be combined with the spatial resolution and flexibility of the transmission electron microscope, it would open up the study of vibrational modes in many different types of nanostructures. Unfortunately, the energy resolution of electron energy loss spectroscopy performed in the electron microscope has until now been too poor to allow such a combination. Recent developments that have improved the attainable energy resolution of electron energy loss spectroscopy in a scanning transmission electron microscope to around ten millielectronvolts now allow vibrational spectroscopy to be carried out in the electron microscope. Here we describe the innovations responsible for the progress, and present examples of applications in inorganic and organic materials, including the detection of hydrogen. We also demonstrate that the vibrational signal has both high- and low-spatial-resolution components, that the first component can be used to map vibrational features at nanometre-level resolution, and that the second component can be used for analysis carried out with the beam positioned just outside the sample--that is, for 'aloof' spectroscopy that largely avoids radiation damage.

Electron spectroscopy analysis

NASA Technical Reports Server (NTRS)

Gregory, John C.

1992-01-01

The Surface Science Laboratories at the University of Alabama in Huntsville (UAH) are equipped with x-ray photoelectron spectroscopy (XPS or ESCA) and Auger electron spectroscopy (AES) facilities. These techniques provide information from the uppermost atomic layers of a sample, and are thus truly surface sensitive. XPS provides both elemental and chemical state information without restriction on the type of material that can be analyzed. The sample is placed into an ultra high vacuum (UHV) chamber and irradiated with x-rays which cause the ejection of photoelectrons from the sample surface. Since x-rays do not normally cause charging problems or beam damage, XPS is applicable to a wide range of samples including metals, polymers, catalysts, and fibers. AES uses a beam of high energy electrons as a surface probe. Following electronic rearrangements within excited atoms by this probe, Auger electrons characteristic of each element present are emitted from the sample. The main advantage of electron induced AES is that the electron beam can be focused down to a small diameter and localized analysis can be carried out. On the rastering of this beam synchronously with a video display using established scanning electron microscopy techniques, physical images and chemical distribution maps of the surface can be produced. Thus very small features, such as electronic circuit elements or corrosion pits in metals, can be investigated. Facilities are available on both XPS and AES instruments for depth-profiling of materials, using a beam of argon ions to sputter away consecutive layers of material to reveal sub-surface (and even semi-bulk) analyses.

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.

i-Assess: Evaluating the impact of electronic data capture for OSCE.

PubMed

Monteiro, Sandra; Sibbald, Debra; Coetzee, Karen

2018-04-01

Tablet-based assessments offer benefits over scannable-paper assessments; however, there is little known about the impact to the variability of assessment scores. Two studies were conducted to evaluate changes in rating technology. Rating modality (paper vs tablets) was manipulated between candidates (Study 1) and within candidates (Study 2). Average scores were analyzed using repeated measures ANOVA, Cronbach's alpha and generalizability theory. Post-hoc analyses included a Rasch analysis and McDonald's omega. Study 1 revealed a main effect of modality (F (1,152) = 25.06, p < 0.01). Average tablet-based scores were higher, (3.39/5, 95% CI = 3.28 to 3.51), compared with average scan-sheet scores (3.00/5, 95% CI = 2.90 to 3.11). Study 2 also revealed a main effect of modality (F (1, 88) = 15.64, p < 0.01), however, the difference was reduced to 2% with higher scan-sheet scores (3.36, 95% CI = 3.30 to 3.42) compared with tablet scores (3.27, 95% CI = 3.21 to 3.33). Internal consistency (alpha and omega) remained high (>0.8) and inter-station reliability remained constant (0.3). Rasch analyses showed no relationship between station difficulty and rating modality. Analyses of average scores may be misleading without an understanding of internal consistency and overall reliability of scores. Although updating to tablet-based forms did not result in systematic variations in scores, routine analyses ensured accurate interpretation of the variability of assessment scores. This study demonstrates the importance of ongoing program evaluation and data analysis.

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.

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.

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.

Fast-Dissolving Core-Shell Composite Microparticles of Quercetin Fabricated Using a Coaxial Electrospray Process

PubMed Central

Li, Chen; Yu, Deng-Guang; Williams, Gareth R.; Wang, Zhuan-Hua

2014-01-01

This study reports on novel fast-dissolving core-shell composite microparticles of quercetin fabricated using coaxial electrospraying. A PVC-coated concentric spinneret was developed to conduct the electrospray process. A series of analyses were undertaken to characterize the resultant particles in terms of their morphology, the physical form of their components, and their functional performance. Scanning and transmission electron microscopies revealed that the microparticles had spherical morphologies with clear core-shell structure visible. Differential scanning calorimetry and X-ray diffraction verified that the quercetin active ingredient in the core and sucralose and sodium dodecyl sulfate (SDS) excipients in the shell existed in the amorphous state. This is believed to be a result of second-order interactions between the components; these could be observed by Fourier transform infrared spectroscopy. In vitro dissolution and permeation studies showed that the microparticles rapidly released the incorporated quercetin within one minute, and had permeation rates across the sublingual mucosa around 10 times faster than raw quercetin. PMID:24643072

Hot corrosion evaluation of aluminide coated superalloys in support of an ASTM Round Robin program

NASA Technical Reports Server (NTRS)

Santoro, G.

1975-01-01

Commercial aluminized coatings on substrates were hot corroded at 900 C in a 0.3 Mach burner rig with 5 ppm synthetic sea salt and at two cycling frequencies. Extensive post-exposure examinations were conducted on the corroded specimens such as metallography, X-ray diffraction, scanning electron microscopy, microprobe raster scans, and spectrographic analyses. Thermodynamic calculations were made of the equilibrium burner flame composition and the calculations were compared to the experimental findings. It was found that localized spalling of the coatings preceded coating failure. It is suggested that the spalling of the coatings is due to the formation of localized stresses caused by the depletion of chromium and aluminum in the coating or the enrichment of the coating with sulfur. For the materials and test conditions investigated, it was found that coating life is dependent only upon the initial coating thickness and not on the type of aluminized coating, the substrate, or the cycle frequency.