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Sample records for actively electronically scanned

  1. UAVSAR Active Electronically Scanned Array

    NASA Technical Reports Server (NTRS)

    Sadowy, Gregory, A.; Chamberlain, Neil F.; Zawadzki, Mark S.; Brown, Kyle M.; Fisher, Charles D.; Figueroa, Harry S.; Hamilton, Gary A.; Jones, Cathleen E.; Vorperian, Vatche; Grando, Maurio B.

    2011-01-01

    The Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR) is a pod-based, L-band (1.26 GHz), repeatpass, interferometric, synthetic aperture radar (InSAR) used for Earth science applications. Repeat-pass interferometric radar measurements from an airborne platform require an antenna that can be steered to maintain the same angle with respect to the flight track over a wide range of aircraft yaw angles. In order to be able to collect repeat-pass InSAR data over a wide range of wind conditions, UAVSAR employs an active electronically scanned array (AESA). During data collection, the UAVSAR flight software continuously reads the aircraft attitude state measured by the Embedded GPS/INS system (EGI) and electronically steers the beam so that it remains perpendicular to the flight track throughout the data collection

  2. 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.

  3. Scanning electron microscopy in the investigation of the in vitro hemolytic activity of Trichomonas vaginalis.

    PubMed

    Rosset, Iveli; Tasca, Tiana; Tessele, Paola M; De Carli, Geraldo A

    2002-04-01

    The in vitro hemolytic activity of Trichomonas vaginalis has been previously demonstrated, but the mechanisms involved remain to be elucidated. In this work we used scanning electron microscopy to investigate the contact dependency of the hemolytic phenomenon caused by the parasites. The erythrocytes adhered to the parasites' surface and were phagocytosed. These observations suggest that the contact between T. vaginalis and erythrocytes may be an important mechanism in the injury caused to the erythrocytes. The hemolytic activity of T. vaginalis may be an efficient means of obtaining nutrients for the parasite and allow the investigation of the mechanism used by T. vaginalis to damage cellular membranes.

  4. Forensic Scanning Electron Microscope

    NASA Astrophysics Data System (ADS)

    Keeley, R. H.

    1983-03-01

    The scanning electron microscope equipped with an x-ray spectrometer is a versatile instrument which has many uses in the investigation of crime and preparation of scientific evidence for the courts. Major applications include microscopy and analysis of very small fragments of paint, glass and other materials which may link an individual with a scene of crime, identification of firearms residues and examination of questioned documents. Although simultaneous observation and chemical analysis of the sample is the most important feature of the instrument, other modes of operation such as cathodoluminescence spectrometry, backscattered electron imaging and direct x-ray excitation are also exploited. Marks on two bullets or cartridge cases can be compared directly by sequential scanning with a single beam or electronic linkage of two instruments. Particles of primer residue deposited on the skin and clothing when a gun is fired can be collected on adhesive tape and identified by their morphology and elemental composition. It is also possible to differentiate between the primer residues of different types of ammunition. Bullets may be identified from the small fragments left behind as they pass through the body tissues. In the examination of questioned documents the scanning electron microscope is used to establish the order in which two intersecting ink lines were written and to detect traces of chemical markers added to the security inks on official documents.

  5. Confocal laser scanning, scanning electron, and transmission electron microscopy investigation of Enterococcus faecalis biofilm degradation using passive and active sodium hypochlorite irrigation within a simulated root canal model.

    PubMed

    Mohmmed, Saifalarab A; Vianna, Morgana E; Penny, Matthew R; Hilton, Stephen T; Mordan, Nicola; Knowles, Jonathan C

    2017-02-28

    Root canal irrigation is an important adjunct to control microbial infection. The aim of this study was to investigate the effect of 2.5% (wt/vol) sodium hypochlorite (NaOCl) agitation on the removal, killing, and degradation of Enterococcus faecalis biofilm. A total of 45 root canal models were manufactured using 3D printing with each model comprising an 18 mm length simulated root canal of apical size 30 and taper 0.06. E. faecalis biofilms were grown on the apical 3 mm of the models for 10 days. A total of 60 s of 9 ml of 2.5% NaOCl irrigation using syringe and needle was performed, the irrigant was either left stagnant in the canal or agitated using manual (Gutta-percha), sonic, and ultrasonic methods for 30 s. Following irrigation, the residual biofilms were observed using confocal laser scanning, scanning electron, and transmission electron microscopy. The data were analyzed using one-way ANOVA with Dunnett post hoc tests at a level of significance p ≤ .05. Consequence of root canal irrigation indicate that the reduction in the amount of biofilm achieved with the active irrigation groups (manual, sonic, and ultrasonic) was significantly greater when compared with the passive and untreated groups (p < .05). Collectively, finding indicate that passive irrigation exhibited more residual biofilm on the model surface than irrigant agitated by manual or automated (sonic, ultrasonic) methods. Total biofilm degradation and nonviable cells were associated with the ultrasonic group.

  6. Tritrichomonas foetus: a scanning electron microscopy study of erythrocyte adhesion associated with hemolytic activity.

    PubMed

    De Carli, Geraldo Attilio; Tasca, Tiana; Pires Borges, Fernanda

    2004-01-01

    The in vitro hemolytic activity of Tritrichomonas foetus was investigated. The parasite was tested against human erythrocytes of groups A, B, AB, and O, and against erythrocytes of nine adult animals of different species (the rabbit, rat, chicken, cat, dog, swine, horse, bovine, and sheep). The results showed that T. foetus strains (ATCC KV1, K, PAL, 5022, RJ, 90) did not present any hemolytic activity against any human erythrocyte group nor against rabbit, rat, chicken, cat, dog and swine erythrocytes. T. foetus strains, however, lysed horse, bovine, and sheep erythrocytes. No hemolysin released by the parasites could be identified. Hemolysis did not occur with trichomonad culture supernatants, with sonicated extracts of T. foetus, nor with killed organisms. Scanning electron microscopy (SEM) showed that human erythrocytes did not adhere to the trophozoites, in contrast horse erythrocytes adhered to the surface of the parasites and were phagocytosed for up to 90 min. The parasites are able to exert their cytopathic effects through: (a) physical contact established between the two cell surfaces, (b) toxins released from parasites into the interaction media, or (c) the association of both mechanisms. Further studies are necessary to clarify the importance of the hemolytic activity in the biology of T. foetus.

  7. SYSTEMATIC SCANNING ELECTRON MICROSCOPY TECHNIQUE FOR EVALUATING COMBINED BIOLOIGCAL/GRANULAR ACTIVATED CARBON TREATMENT PROCESSES

    EPA Science Inventory

    A systematic scanning election microscope analytical technique has been developed to examine granular activated carbon used a a medium for biomass attachment in liquid waste treatment. The procedure allows for the objective monitoring, comparing, and trouble shooting of combined ...

  8. Scanning electron microscopic description of cellular activity and mineral changes in feline odontoclastic resorptive lesions.

    PubMed

    Gauthier, O; Boudigues, S; Pilet, P; Aguado, E; Heymann, D; Daculsi, G

    2001-12-01

    The cellular activity and changes in mineral composition of dental tissues involved in feline odontoclastic resorptive lesions were investigated. Teeth with at least 1 lesion (n = 10) were extracted from 10 different cats that were presented primarily for chronic gingivostomatitis and/or severe periodontal disease. Scanning electron microscopic methods were used to determine the presence of resorptive cells in 8 teeth while 2 teeth were evaluated for pathologic changes in dental mineral composition. Observations were complicated by the presence of organic wear on the dental surfaces, however resorptive cells could be clearly identified in feline odontoclastic resorptive lesions. Resorptive cells had morphologic features indicative of "osteoclast-like" cells or odontoclasts. Resorptive cell activity created a resorption area of darker dentin continuous with physiologic dentin. The darker dentin area seemed poorly mineralized and showed a significantly lower calcium/phosphorous ratio compared with adjacent physiologic denting in 1 tooth. A significantly higher level of magnesium combined with available carbonate ions may have increased the solubility in areas of darker dentin.

  9. Low Voltage Scanning Electron Microscopy

    DTIC Science & Technology

    1988-10-01

    Microscopy List of Keywords ,Scanning electron microscopy SEM X -ray .Micoranalysis EDX/EDS -%Low voltage , High resolution -Ceramic surfaces Supported...energy component normal to the surface). (a) Applications to x -ray microanalysis The essential problem leading to the specification of a LVSEM is...illustrated (Fig.l), for a conventional microprobe operated with 20nA probe current, by the contrast of the alumunium (K) x -ray signal as the probe is scanned

  10. A Scanning electron microscopic evaluation of intracanal smear layer removal by two different final irrigation activation systems

    PubMed Central

    Dua, Deepti; Dua, Ankur; Uppin, Veerendra M.

    2014-01-01

    Aim: The aim of this study was to compare smear layer removal at apical 1 mm level after final irrigation activation with an EndoVac system and Max-I probe. Materials and Methods: Fifty freshly extracted maxillary central incisors were randomly divided into two groups after completing cleaning and shaping with ProTaper rotary files. In one group, final irrigation was performed with an EndoVac system while in the other group final irrigation was performed with a 30 gauge Max-I probe. 3% sodium hypochlorite and 17% ethylenediaminetetracetic acid were used as final irrigants in all teeth. After instrumentation and irrigation, the teeth were sectioned longitudinally into buccal and palatal halves and viewed under a scanning electron microscope for evaluation of the smear layer. Statistical analysis was performed using the Kruskal Wallis and Mann-Whitney U tests. Results: The EndoVac group showed significantly better smear layer removal compared with the Max-I probe at the apical 1 mm level. Conclusion: An apical negative pressure system (EndoVac) results in better debridement at apical 1 mm when compared with side-vented closed ended needle irrigation (Max-I probe). PMID:24808693

  11. Phase multiplying electronic scanning array

    NASA Technical Reports Server (NTRS)

    Seaton, A. F.

    1969-01-01

    Scanning array was designed with properties of low RF loss and phase control. The array consists of a series of special waveguides, hybrids made up of two variable reactance branch arms for input signals, an edge slot for the difference port, and a sum arm for the unradiated signal.

  12. 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…

  13. Real time anti-Toxoplasma gondii activity of an active fraction of Eurycoma longifolia root studied by in situ scanning and transmission electron microscopy.

    PubMed

    Kavitha, Nowroji; Noordin, Rahmah; Kit-Lam, Chan; Sasidharan, Sreenivasan

    2012-08-02

    The inhibitory effect of active fractions of Eurycoma longifolia (E. longifolia) root, namely TAF355 and TAF401, were evaluated against Toxoplasma gondii (T. gondii). In our previous study, we demonstrated that T. gondii was susceptible to TAF355 and TAF401 with IC₅₀ values of 1.125 µg/mL and 1.375 µg/mL, respectively. Transmission (TEM) and scanning electron microscopy (SEM) observations were used to study the in situ antiparasitic activity at the IC₅₀ value. Clindamycin was used as positive control. SEM examination revealed cell wall alterations with formation of invaginations followed by completely collapsed cells compared to the normal T. gondii cells in response to the fractions. The main abnormality noted via TEM study was decreased cytoplasmic volume, leaving a state of structural disorganization within the cell cytoplasm and destruction of its organelles as early as 12 h of treatment, which indicated of rapid antiparasitic activity of the E. longifolia fractions. The significant antiparasitic activity shown by the TAF355 and TAF401 active fractions of E. longifolia suggests their potential as new anti-T. gondii agent candidates.

  14. Gigahertz-band electronically scanned antennas

    NASA Astrophysics Data System (ADS)

    Bei, Nikolai A.

    2000-12-01

    Foundation and principles of radio lenses construction of centimeter and millimeter wave ranges with controlled refracting index, combining the quality of phased array antennas with optical devices are stated. Possibilities of the electronically scanning with wide-angle sector and high gain are maintained. Construction principles of scanning antennas with controlled lenses, combining the quality of phased array antennas with optical devices, are stated. Possibilities of electronically scanning with broad angle sector and high gain are maintained. Some examples of construction of antennas millimeter range of waves are listed here.

  15. Feature Adaptive Sampling for Scanning Electron Microscopy

    PubMed Central

    Dahmen, Tim; Engstler, Michael; Pauly, Christoph; Trampert, Patrick; de Jonge, Niels; Mücklich, Frank; Slusallek, Philipp

    2016-01-01

    A new method for the image acquisition in scanning electron microscopy (SEM) was introduced. The method used adaptively increased pixel-dwell times to improve the signal-to-noise ratio (SNR) in areas of high detail. In areas of low detail, the electron dose was reduced on a per pixel basis, and a-posteriori image processing techniques were applied to remove the resulting noise. The technique was realized by scanning the sample twice. The first, quick scan used small pixel-dwell times to generate a first, noisy image using a low electron dose. This image was analyzed automatically, and a software algorithm generated a sparse pattern of regions of the image that require additional sampling. A second scan generated a sparse image of only these regions, but using a highly increased electron dose. By applying a selective low-pass filter and combining both datasets, a single image was generated. The resulting image exhibited a factor of ≈3 better SNR than an image acquired with uniform sampling on a Cartesian grid and the same total acquisition time. This result implies that the required electron dose (or acquisition time) for the adaptive scanning method is a factor of ten lower than for uniform scanning. PMID:27150131

  16. Radant - New method of electronic scanning

    NASA Astrophysics Data System (ADS)

    Chekroun, C.; Herrick, D.; Michel, Y. M.; Pauchard, R.; Vidal, P.

    1981-02-01

    The paper describes a novel electronic scanning process that differs from the conventional phased array process. Called Radant (from radome antennas), the process uses an electromagnetic lens such that the direction of the optical axis can be changed electronically. The principle of this process and a working model are described.

  17. Electron Beam Scanning in Industrial Applications

    NASA Astrophysics Data System (ADS)

    Jongen, Yves; Herer, Arnold

    1996-05-01

    Scanned electron beams are used within many industries for applications such as sterilization of medical disposables, crosslinking of wire and cables insulating jackets, polymerization and degradation of resins and biomaterials, modification of semiconductors, coloration of gemstones and glasses, removal of oxides from coal plant flue gasses, and the curing of advanced composites and other molded forms. X-rays generated from scanned electron beams make yet other applications, such as food irradiation, viable. Typical accelerators for these applications range in beam energy from 0.5MeV to 10 MeV, with beam powers between 5 to 500kW and scanning widths between 20 and 300 cm. Since precise control of dose delivery is required in many of these applications, the integration of beam characteristics, product conveyance, and beam scanning mechanisms must be well understood and optimized. Fundamental issues and some case examples are presented.

  18. Development of Scanning Ultrafast Electron Microscope Capability.

    SciTech Connect

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

    2016-11-01

    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 Laboratories based on the original Caltech design. This effort represents Sandia's first exploration into ultrafast electron microscopy.

  19. 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.

  20. Scanning electron microscopy study of Trichomonas gallinae.

    PubMed

    Tasca, Tiana; De Carli, Geraldo A

    2003-12-01

    A scanning electron microscopy (SEM) study of Trichomonas gallinae (Rivolta, 1878), provided more information about the morphology of this flagellated protozoan. SEM showed the morphological features of the trophozoites; the emergence of the anterior flagella, the structure of the undulating membrane, the position and shape of the pelta, axostyle and posterior flagellum. Of special interest were the pseudocyst forms.

  1. Scanning electron microscopy studies of bacterial cultures

    NASA Astrophysics Data System (ADS)

    Swinger, Tracy; Blust, Brittni; Calabrese, Joseph; Tzolov, Marian

    2012-02-01

    Scanning electron microscopy is a powerful tool to study the morphology of bacteria. We have used conventional scanning electron microscope to follow the modification of the bacterial morphology over the course of the bacterial growth cycle. The bacteria were fixed in vapors of Glutaraldehyde and ruthenium oxide applied in sequence. A gold film of about 5 nm was deposited on top of the samples to avoid charging and to enhance the contrast. We have selected two types of bacteria Alcaligenes faecalis and Kocuria rhizophila. Their development was carefully monitored and samples were taken for imaging in equal time intervals during their cultivation. These studies are supporting our efforts to develop an optical method for identification of the Gram-type of bacterial cultures.

  2. Cryogenic Multichannel Pressure Sensor With Electronic Scanning

    NASA Technical Reports Server (NTRS)

    Hopson, Purnell, Jr.; Chapman, John J.; Kruse, Nancy M. H.

    1994-01-01

    Array of pressure sensors operates reliably and repeatably over wide temperature range, extending from normal boiling point of water down to boiling point of nitrogen. Sensors accurate and repeat to within 0.1 percent. Operate for 12 months without need for recalibration. Array scanned electronically, sensor readings multiplexed and sent to desktop computer for processing and storage. Used to measure distributions of pressure in research on boundary layers at high Reynolds numbers, achieved by low temperatures.

  3. Scanning electron microscope view of iron crystal

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A scanning electron microscope photograph of iron crystals which grow in a small vug or cavity in a recrystallized breccia (fragmented rock) from the Apollo 15 Hadley-Apennino lunar landing site. The largest crystal is three microns across. Perfectly developed crystals such as these indicate slow formation from a hot vapor as the rock was cooling. The crystals are resting on an interlocking lattice of pyroxene (calsium-magnesium-iron silicate).

  4. 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.

  5. Antimicrobial activity of various extracts of Ocimum basilicum L. and observation of the inhibition effect on bacterial cells by use of scanning electron microscopy.

    PubMed

    Kaya, Ilhan; Yigit, Nazife; Benli, Mehlika

    2008-06-18

    The antimicrobial activities of chloroform, acetone and two different concentrations of methanol extracts of Ocimum basilicum L. were studied. These extracts were tested in vitro against 10 bacteria and 4 yeasts strains by the disc diffusion method. The results indicated that the methanol extracts of O. basilucum exhibited the antimicrobial activity against tested microorganisms. While the chloroform and acetone extracts had no effect, the methanol extracts showed inhibition zones against strains of Pseudomonas aeruginosa, Shigella sp., Listeria monocytogenes, Staphylococcus aureus and two different strains of Escherichia coli. The cells of microorganisms, which were treated and untreated with plant extracts, were observed by using the scanning electron microscope. It was observed that the treated cells were damaged.

  6. Scanning electron microscopy study of Tritrichomonas augusta.

    PubMed

    Borges, Fernanda P; Wiltuschnig, Renata C M; Tasca, Tiana; De Carli, Geraldo A

    2004-09-01

    Tritrichomonas augusta is a flagellated protozoan that parasitizes amphibians and reptiles. According to scanning electron microscopy (SEM), the cell shape of T. augusta varies from slender pyriform to ovoidal. Our data show the morphological features of the trophozoites: the emergence of the anterior flagella, the structure of the undulating membrane and the position and shape of the pelta, axostyle and posterior flagellum. In addition, herein we describe spherical forms which are probably pseudocysts. The description of the external structure of T. augusta, as demonstrated by SEM, contributes to the understanding of the biology of this parasite.

  7. Aberration corrected Lorentz scanning transmission electron microscopy.

    PubMed

    McVitie, S; McGrouther, D; McFadzean, S; MacLaren, D A; O'Shea, K J; Benitez, M J

    2015-05-01

    We present results from an aberration corrected scanning transmission electron microscope which has been customised for high resolution quantitative Lorentz microscopy with the sample located in a magnetic field free or low field environment. We discuss the innovations in microscope instrumentation and additional hardware that underpin the imaging improvements in resolution and detection with a focus on developments in differential phase contrast microscopy. Examples from materials possessing nanometre scale variations in magnetisation illustrate the potential for aberration corrected Lorentz imaging as a tool to further our understanding of magnetism on this lengthscale.

  8. Ultrasonic versus sonic activation of the final irrigant in root canals instrumented with rotary/reciprocating files: An in-vitro scanning electron microscopy analysis

    PubMed Central

    Khalap, Neha Deepak; Kokate, Sharad; Hegde, Vibha

    2016-01-01

    Aim: To compare the smear layer and debris removal in root canals instrumented with two different kinematic motions after ultrasonic and sonic irrigation activation. Materials and Methods: Eighty freshly extracted teeth were selected for the study and randomly divided the samples into two groups (n = 40) for instrumentation with either rotary ProTaper NEXT (PTN) or reciprocating WaveOne (WO) file systems. These (n = 40) were further divided into two groups (n = 20) where the final irrigant was activated using either Ultrasonics (Passive Ultrasonic Irrigation; PUI) or Sonics (EndoActivator; EA). Group 1: PTN + EA; Group 2: PTN + PUI; Group 3: WO + EA; and Group 4: WO + PUI. During instrumentation, a total of 4 ml of 5.25% NaOCl was used for irrigation. The final irrigation protocol included NaOCl and Smear Clear Solution. The samples were processed by scanning electron microscopic examination for debris and smear layer scoring, and statistical analysis was done. Results: The mean debris and smear layer score was less in the group instrumented by PTN with sonic activation of the irrigant. Conclusion: A combination of PTN instrumentation with sonic irrigation activation by EA is more effective in debris and smear layer removal in the groups tested. PMID:27563189

  9. 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.

  10. Phase-contrast scanning transmission electron microscopy.

    PubMed

    Minoda, Hiroki; Tamai, Takayuki; Iijima, Hirofumi; Hosokawa, Fumio; Kondo, Yukihito

    2015-06-01

    This report introduces the first results obtained using phase-contrast scanning transmission electron microscopy (P-STEM). A carbon-film phase plate (PP) with a small center hole is placed in the condenser aperture plane so that a phase shift is introduced in the incident electron waves except those passing through the center hole. A cosine-type phase-contrast transfer function emerges when the phase-shifted scattered waves interfere with the non-phase-shifted unscattered waves, which passed through the center hole before incidence onto the specimen. The phase contrast resulting in P-STEM is optically identical to that in phase-contrast transmission electron microscopy that is used to provide high contrast for weak phase objects. Therefore, the use of PPs can enhance the phase contrast of the STEM images of specimens in principle. The phase shift resulting from the PP, whose thickness corresponds to a phase shift of π, has been confirmed using interference fringes displayed in the Ronchigram of a silicon single crystal specimen. The interference fringes were found to abruptly shift at the edge of the PP hole by π.

  11. Scanning electron microscopy of tinea nigra.

    PubMed

    Guarenti, Isabelle Maffei; Almeida, Hiram Larangeira de; Leitão, Aline Hatzenberger; Rocha, Nara Moreira; Silva, Ricardo Marques E

    2014-01-01

    Tinea nigra is a rare superficial mycosis caused by Hortaea werneckii. This infection presents as asymptomatic brown to black maculae mostly in palmo-plantar regions. We performed scanning electron microscopy of a superficial shaving of a tinea nigra lesion. The examination of the outer surface of the sample showed the epidermis with corneocytes and hyphae and elimination of fungal filaments. The inner surface of the sample showed important aggregation of hyphae among keratinocytes, which formed small fungal colonies. The ultrastructural findings correlated with those of dermoscopic examination - the small fungal aggregations may be the dark spicules seen on dermoscopy - and also allowed to document the mode of dissemination of tinea nigra, showing how hyphae are eliminated on the surface of the lesion.

  12. Scanning electron microscopy of molluscum contagiosum*

    PubMed Central

    de Almeida Jr, Hiram Larangeira; Abuchaim, Martha Oliveira; Schneider, Maiko Abel; Marques, Leandra; de Castro, Luis Antônio Suíta

    2013-01-01

    Molluscum contagiosum is a disease caused by a poxvirus. It is more prevalent in children up to 5 years of age. There is a second peak of incidence in young adults. In order to examine its ultrastructure, three lesions were curetted without disruption, cut transversely with a scalpel, and routinely processed for scanning electron microscopy (SEM). The oval structure of molluscum contagiosum could be easily identified. In its core, there was a central umbilication and just below this depression, there was a keratinized tunnel. Under higher magnification, a proliferation similar to the epidermis was seen. Moreover, there were areas of cells disposed like a mosaic. Under higher magnification, rounded structures measuring 0.4 micron could be observed at the end of the keratinized tunnel and on the surface of the lesion. PMID:23539009

  13. Scanning electron microscopy of lichen sclerosus*

    PubMed Central

    de Almeida, Hiram Larangeira; Bicca, Eduardo de Barros Coelho; Breunig, Juliano de Avelar; Rocha, Nara Moreira; Silva, Ricardo Marques e

    2013-01-01

    Lichen sclerosus is an acquired inflammatory condition characterized by whitish fibrotic plaques, with a predilection for the genital skin. We performed scanning electron microscopy of the dermis from a lesion of lichen sclerosus. Normal collagen fibers could be easily found in deeper layers of the specimen, as well as the transition to pathologic area, which seems homogenized. With higher magnifications in this transitional area collagen fibers are adherent to each other, and with very high magnifications a pearl chain aspect became evident along the collagen fibers. In the superficial dermis this homogenization is even more evident, collagen fibers are packed together and round structures are also observed. Rupture of collagen fibers and inflammatory cells were not found. These autoimmune changes of the extracellular matrix lead to the aggregation of immune complexes and/or changed matrix proteins along the collagen fibers, the reason why they seem hyalinized when examined by light microscopy. PMID:23739707

  14. Scanning electron microscopy of bacteria Tetrasphaera duodecadis.

    PubMed

    Arroyo, E; Enríquez, L; Sánchez, A; Ovalle, M; Olivas, A

    2014-01-01

    This study reports the characterization of the Tetrasphaera duodecadis bacteria and the techniques used therein. In order to evaluate the morphological characteristics of the T. duodecadis bacteria scanning electron microscope (SEM) was used throughout its different growth stages. These microorganisms were grown in vitamin B12 broths with 1% tryptone, 0.2% yeast extract, and 0.1% glucose. The turbidimetric method was employed for the determination of bacterial concentration and growth curve. The SEM results show small agglomerates of 0.8 ± 0.05 µm during the lag phase, and rod-like shapes during the exponential phase with similar shapes in the stationary phase.

  15. Electric fields in Scanning Electron Microscopy simulations

    NASA Astrophysics Data System (ADS)

    Arat, K. T.; Bolten, J.; Klimpel, T.; Unal, N.

    2016-03-01

    The electric field distribution and charging effects in Scanning Electron Microscopy (SEM) were studied by extending a Monte-Carlo based SEM simulator by a fast and accurate multigrid (MG) based 3D electric field solver. The main focus is on enabling short simulation times with maintaining sufficient accuracy, so that SEM simulation can be used in practical applications. The implementation demonstrates a gain in computation speed, when compared to a Gauss-Seidel based reference solver is roughly factor of 40, with negligible differences in the result (~10-6 𝑉). In addition, the simulations were compared with experimental SEM measurements using also complex 3D sample, showing that i) the modelling of e-fields improves the simulation accuracy, and ii) multigrid method provide a significant benefit in terms of simulation time.

  16. Hexamethyldisilazane for scanning electron microscopy of Gastrotricha.

    PubMed

    Hochberg, R; Litvaitis, M K

    2000-01-01

    We evaluated treatment with hexamethyldisilazane (HMDS) as an alternative to critical-point drying (CPD) for preparing microscopic Gastrotricha for scanning electron microscopy (SEM). We prepared large marine (2 mm) and small freshwater (100 microm) gastrotrichs using HMDS as the primary dehydration solvent and compared the results to earlier investigations using CPD. The results of HMDS dehydration are similar to or better than CPD for resolution of two important taxonomic features: cuticular ornamentation and patterns of ciliation. The body wall of both sculpted (Lepidodermella) and smooth (Dolichodasys) gastrotrichs retained excellent morphology as did the delicate sensory and locomotory cilia. The only unfavorable result of HMDS dehydration was an occasional coagulation of gold residue when the solvent had not fully evaporated before sputter-coating. We consider HMDS an effective alternative for preparing of gastrotrichs for SEM because it saves time and expense compared to CPD.

  17. Correlative photoactivated localization and scanning electron microscopy.

    PubMed

    Kopek, Benjamin G; Shtengel, Gleb; Grimm, Jonathan B; Clayton, David A; Hess, Harald F

    2013-01-01

    The ability to localize proteins precisely within subcellular space is crucial to understanding the functioning of biological systems. Recently, we described a protocol that correlates a precise map of fluorescent fusion proteins localized using three-dimensional super-resolution optical microscopy with the fine ultrastructural context of three-dimensional electron micrographs. While it achieved the difficult simultaneous objectives of high photoactivated fluorophore preservation and ultrastructure preservation, it required a super-resolution optical and specialized electron microscope that is not available to many researchers. We present here a faster and more practical protocol with the advantage of a simpler two-dimensional optical (Photoactivated Localization Microscopy (PALM)) and scanning electron microscope (SEM) system that retains the often mutually exclusive attributes of fluorophore preservation and ultrastructure preservation. As before, cryosections were prepared using the Tokuyasu protocol, but the staining protocol was modified to be amenable for use in a standard SEM without the need for focused ion beam ablation. We show the versatility of this technique by labeling different cellular compartments and structures including mitochondrial nucleoids, peroxisomes, and the nuclear lamina. We also demonstrate simultaneous two-color PALM imaging with correlated electron micrographs. Lastly, this technique can be used with small-molecule dyes as demonstrated with actin labeling using phalloidin conjugated to a caged dye. By retaining the dense protein labeling expected for super-resolution microscopy combined with ultrastructural preservation, simplifying the tools required for correlative microscopy, and expanding the number of useful labels we expect this method to be accessible and valuable to a wide variety of researchers.

  18. A microscopy method for scanning transmission electron microscopy imaging of the antibacterial activity of polymeric nanoparticles on a biofilm with an ionic liquid.

    PubMed

    Takahashi, Chisato; Muto, Shunsuke; Yamamoto, Hiromitsu

    2016-04-18

    In this study, we developed a scanning transmission electron microscopy (STEM) method for imaging the antibacterial activity of organic polymeric nanoparticles (NPs) toward biofilms formed by Staphylococcus epidermidis bacterial cells, for optimizing NPs to treat biofilm infections. The combination of sample preparation method using a hydrophilic ionic liquid (IL) and STEM observation using the cooling holder eliminates the need for specialized equipment and techniques for biological sample preparation. The annular dark-field STEM results indicated that the two types of biodegradable poly-(DL-lactide-co-glycolide) (PLGA) NPs: PLGA modified with chitosan (CS), and clarithromycin (CAM)-loaded + CS-modified PLGA, prepared by emulsion solvent diffusion exhibited different antibacterial activities in nanoscale. To confirm damage to the sample during STEM observation, we observed the PLGA NPs and the biofilm treated with PLGA NPs by both the conventional method and the newly developed method. The optimized method allows microstructure of the biofilm treated with PLGA NPs to be maintained for 25 min at a current flow of 40 pA. The developed simple sample preparation method would be helpful to understand the interaction of drugs with target materials. In addition, this technique could contribute to the visualization of other deformable composite materials at the nanoscale level. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  19. Effectiveness of Four Different Final Irrigation Activation Techniques on Smear Layer Removal in Curved Root Canals : A Scanning Electron Microscopy Study

    PubMed Central

    Ahuja, Puneet; Nandini, Suresh; Ballal, Suma; Velmurugan, Natanasabapathy

    2014-01-01

    Objective: The aim of this study was to assess the efficacy of apical negative pressure (ANP), manual dynamic agitation (MDA), passive ultrasonic irrigation (PUI) and needle irrigation (NI) as final irrigation activation techniques for smear layer removal in curved root canals. Materials and Methods: Mesiobuccal root canals of 80 freshly extracted maxillary first molars with curvatures ranging between 25° and 35° were used. A glide path with #08–15 K files was established before cleaning and shaping with Mtwo rotary instruments (VDW, Munich, Germany) up to size 35/0.04 taper. During instrumentation, 1 ml of 2.5% NaOCl was used at each change of file. Samples were divided into 4 equal groups (n=20) according to the final irrigation activation technique: group 1, apical negative pressure (ANP) (EndoVac); group 2, manual dynamic agitation (MDA); group 3, passive ultrasonic irrigation (PUI); and group 4, needle irrigation (NI). Root canals were split longitudinally and subjected to scanning electron microscopy. The presence of smear layer at coronal, middle and apical levels was evaluated by superimposing 300-μm square grid over the obtained photomicrographs using a four-score scale with X1,000 magnification. Results: Amongst all the groups tested, ANP showed the overall best smear layer removal efficacy (p < 0.05). Removal of smear layer was least effective with the NI technique. Conclusion: ANP (EndoVac system) can be used as the final irrigation activation technique for effective smear layer removal in curved root canals. PMID:24910670

  20. Electronic scan at millimetre wave frequencies

    NASA Astrophysics Data System (ADS)

    Snieder, J.

    1990-06-01

    The possibilities of realizing phased array antennas in the mm wave region are reviewed. The use of discrete components and bulk material is discussed. The MMIC (Monolithic Microwave Integrated Circuits) techniques for the realization of phased array components are excluded from this report. A survey is given of the different electronic scan possibilities. PIN diode phase shifters and different types of ferrite phase shifters are discussed, including the principle functioning of these components as well as the advantages involved in their use. The availability of various ferrite materials for phase shifters is discussed. The requirements for phased array antennas and its phase shifters are given. A discussion of array element spacing, side lobe level and related power levels, effect of pulse repetition frequency and mutual coupling are presented. An attempt is made to correlate all the available information at cm wavelength (3 to 18 GHz) and to extrapolate it to mm wavelength. All the detailed properties of the phase shifters are included. The experimental results of mm wave phase shifters are given and compared with the extrapolated results given.

  1. Dental Wear: A Scanning Electron Microscope Study

    PubMed Central

    Levrini, Luca; Di Benedetto, Giulia

    2014-01-01

    Dental wear can be differentiated into different types on the basis of morphological and etiological factors. The present research was carried out on twelve extracted human teeth with dental wear (three teeth showing each type of wear: erosion, attrition, abrasion, and abfraction) studied by scanning electron microscopy (SEM). The study aimed, through analysis of the macro- and micromorphological features of the lesions (considering the enamel, dentin, enamel prisms, dentinal tubules, and pulp), to clarify the different clinical and diagnostic presentations of dental wear and their possible significance. Our results, which confirm current knowledge, provide a complete overview of the distinctive morphology of each lesion type. It is important to identify the type of dental wear lesion in order to recognize the contributing etiological factors and, consequently, identify other more complex, nondental disorders (such as gastroesophageal reflux, eating disorders). It is clear that each type of lesion has a specific morphology and mechanism, and further clinical studies are needed to clarify the etiological processes, particularly those underlying the onset of abfraction. PMID:25548769

  2. Dental wear: a scanning electron microscope study.

    PubMed

    Levrini, Luca; Di Benedetto, Giulia; Raspanti, Mario

    2014-01-01

    Dental wear can be differentiated into different types on the basis of morphological and etiological factors. The present research was carried out on twelve extracted human teeth with dental wear (three teeth showing each type of wear: erosion, attrition, abrasion, and abfraction) studied by scanning electron microscopy (SEM). The study aimed, through analysis of the macro- and micromorphological features of the lesions (considering the enamel, dentin, enamel prisms, dentinal tubules, and pulp), to clarify the different clinical and diagnostic presentations of dental wear and their possible significance. Our results, which confirm current knowledge, provide a complete overview of the distinctive morphology of each lesion type. It is important to identify the type of dental wear lesion in order to recognize the contributing etiological factors and, consequently, identify other more complex, nondental disorders (such as gastroesophageal reflux, eating disorders). It is clear that each type of lesion has a specific morphology and mechanism, and further clinical studies are needed to clarify the etiological processes, particularly those underlying the onset of abfraction.

  3. Scanning electron microscopy of softened enamel.

    PubMed

    Eisenburger, M; Shellis, R P; Addy, M

    2004-01-01

    After exposing enamel specimens to 0.3% citric acid at pH 3.2 for various times, the acid was titrated to pH 7 before rinsing the specimens in water. After freeze-drying the specimens were examined by scanning electron microscopy. This procedure eliminates artefacts due to drying and mineral precipitation. The results showed that the outer region of softened enamel is much more delicate than previously thought, even after short (5- to 20-min) etching times. Mineral was lost from both prism boundaries and the prism bodies, resulting in a surface presenting thin, separate crystal bundles. In further studies, replicas of subsurface pores, created by resin impregnation, showed the softening depth to be several times greater than is suggested by techniques based on removing the softened enamel by physical forces. The results point to a need for improved methods of measuring softening depth. More importantly, it appears that the outer region of the softened layer remaining after an erosive challenge might be too fragile to resist frictional forces in vivo.

  4. A dynamic scanning method based on signal-statistics for scanning electron microscopy.

    PubMed

    Timischl, F

    2014-01-01

    A novel dynamic scanning method for noise reduction in scanning electron microscopy and related applications is presented. The scanning method dynamically adjusts the scanning speed of the electron beam depending on the statistical behavior of the detector signal and gives SEM images with uniform and predefined standard deviation, independent of the signal value itself. In the case of partially saturated images, the proposed method decreases image acquisition time without sacrificing image quality. The effectiveness of the proposed method is shown and compared to the conventional scanning method and median filtering using numerical simulations.

  5. 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.

  6. Environmental scanning electron microscopy of personal and household products.

    PubMed

    Hoyberg, K

    1997-03-01

    The ability to forego sample preparation and to make observation directly in the environmental scanning electron microscope has benefited both household and personal product research at Unilever Research. Product efficacy on biological materials such as microcomedones was easily ascertained. Skin biopsies were examined in a moist state with no sample preparation. Effects of relative humidity on detergents were visually determined by recreating the necessary conditions in the microscope. Effects of cooling rates on the morphology of softener sheet actives that remained on polyester fabric were characterized via dynamic experimentation.

  7. Image Resolution in Scanning Transmission Electron Microscopy

    SciTech Connect

    Pennycook, S. J.; Lupini, A.R.

    2008-06-26

    Digital images captured with electron microscopes are corrupted by two fundamental effects: shot noise resulting from electron counting statistics and blur resulting from the nonzero width of the focused electron beam. The generic problem of computationally undoing these effects is called image reconstruction and for decades has proved to be one of the most challenging and important problems in imaging science. This proposal concerned the application of the Pixon method, the highest-performance image-reconstruction algorithm yet devised, to the enhancement of images obtained from the highest-resolution electron microscopes in the world, now in operation at Oak Ridge National Laboratory.

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

    PubMed Central

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

    2017-01-01

    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. PMID:28272404

  9. 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.

  10. 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.

  11. Standardless atom counting in scanning transmission electron microscopy.

    PubMed

    LeBeau, James M; Findlay, Scott D; Allen, Leslie J; Stemmer, Susanne

    2010-11-10

    We demonstrate that high-angle annular dark-field imaging in scanning transmission electron microscopy allows for quantification of the number and location of all atoms in a three-dimensional, crystalline, arbitrarily shaped specimen without the need for a calibration standard. We show that the method also provides for an approach to directly measure the finite effective source size of a scanning transmission electron microscope.

  12. 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.

  13. Theoretical Evaluation of Compositional Contrast of Scanning Electron Microscope Images

    NASA Astrophysics Data System (ADS)

    Kotera, Masatoshi; Yamaguchi, Satoru; Fujiwara, Takafumi; Suga, Hiroshi

    1992-12-01

    The compositional contrast in the scanning electron microscope image is calculated for Al-Cu, Si-Cu and Al-Si contacts. An electron scattering phenomenon in the specimen is simulated in a direct manner. Electron refraction at the boundary, because of the agreement of each Fermi energy at the boundary, is precisely taken into account. The backscattered electron image shows better resolution than the secondary electron image in terms of the boundary contrast when the primary electron energy is 1 keV. The signal intensity varies depending on materials adjacent to the location observed. The ultimate resolution of the compositional contrast of the scanning electron microscope can be below 1 nm.

  14. 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.

  15. Smart flexible microrobots for scanning electron microscope (SEM) applications

    NASA Astrophysics Data System (ADS)

    Schmoeckel, Ferdinand; Fatikow, Sergej

    2000-06-01

    In the scanning electron microscope (SEM), specially designed microrobots can act as a flexible assembly facility for hybrid microsystems, as probing devices for in-situ tests on IC structures or just as a helpful teleoperated tool for the SEM operator when examining samples. Several flexible microrobots of this kind have been developed and tested. Driven by piezoactuators, these few cubic centimeters small mobile robots perform manipulations with a precision of up to 10 nm and transport the gripped objects at speeds of up to 3 cm/s. In accuracy, flexibility and price they are superior to conventional precision robots. A new SEM-suited microrobot prototype is described in this paper. The SEM's vacuum chamber has been equipped with various elements like flanges and CCD cameras to enable the robot to operate. In order to use the SEM image for the automatic real-time control of the robots, the SEM's electron beam is actively controlled by a PC. The latter submits the images to the robots' control computer system. For obtaining three-dimensional information in real time, especially for the closed-loop control of a robot endeffector, e.g. microgripper, a triangulation method with the luminescent spot of the SEM's electron beam is being investigated.

  16. Focused ion beam scanning electron microscopy in biology.

    PubMed

    Kizilyaprak, C; Daraspe, J; Humbel, B M

    2014-06-01

    Since the end of the last millennium, the focused ion beam scanning electron microscopy (FIB-SEM) has progressively found use in biological research. This instrument is a scanning electron microscope (SEM) with an attached gallium ion column and the 2 beams, electrons and ions (FIB) are focused on one coincident point. The main application is the acquisition of three-dimensional data, FIB-SEM tomography. With the ion beam, some nanometres of the surface are removed and the remaining block-face is imaged with the electron beam in a repetitive manner. The instrument can also be used to cut open biological structures to get access to internal structures or to prepare thin lamella for imaging by (cryo-) transmission electron microscopy. Here, we will present an overview of the development of FIB-SEM and discuss a few points about sample preparation and imaging.

  17. 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.

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

    SciTech Connect

    Guo, Hongxuan E-mail: msxu@zju.edu.cn; Gao, Jianhua; Ishida, Nobuyuki; Xu, Mingsheng E-mail: msxu@zju.edu.cn; Fujita, Daisuke

    2014-01-20

    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.

  19. Light and scanning electron microscopic report of four fractured implants.

    PubMed

    Piattelli, A; Piattelli, M; Scarano, A; Montesani, L

    1998-01-01

    Although they are fortunately rare, implant fractures can cause significant problems for both clinicians and patients. The authors present a light and scanning electron microscopic study of four fractured implants in two patients. Both patients had parafunctional habits (bruxism), hypertrophic masticatory muscles, and wear of occlusal surfaces. The scanning electron microscopic study of the fractured surfaces of all four implants showed the presence of fatigue striations. Bending overload was probably created by a combination of parafunctional forces, bone resorption, posterior location of the implants, and implant diameter.

  20. A new clustering algorithm for scanning electron microscope images

    NASA Astrophysics Data System (ADS)

    Yousef, Amr; Duraisamy, Prakash; Karim, Mohammad

    2016-04-01

    A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning it with a focused beam of electrons. The electrons interact with the sample atoms, producing various signals that are collected by detectors. The gathered signals contain information about the sample's surface topography and composition. The electron beam is generally scanned in a raster scan pattern, and the beam's position is combined with the detected signal to produce an image. The most common configuration for an SEM produces a single value per pixel, with the results usually rendered as grayscale images. The captured images may be produced with insufficient brightness, anomalous contrast, jagged edges, and poor quality due to low signal-to-noise ratio, grained topography and poor surface details. The segmentation of the SEM images is a tackling problems in the presence of the previously mentioned distortions. In this paper, we are stressing on the clustering of these type of images. In that sense, we evaluate the performance of the well-known unsupervised clustering and classification techniques such as connectivity based clustering (hierarchical clustering), centroid-based clustering, distribution-based clustering and density-based clustering. Furthermore, we propose a new spatial fuzzy clustering technique that works efficiently on this type of images and compare its results against these regular techniques in terms of clustering validation metrics.

  1. Scanning Electron Microscopy And Data Digitization Of Craniofacial Growth

    NASA Astrophysics Data System (ADS)

    Rice, Robert W.; Oyen, Ordean J.; Walker, Alan C.

    1980-07-01

    The scanning electron microscope (SEM), combining high resolution and large depth of focus, affords detailed observation of surface microstructure in a three-dimensional perspective. It also allows large specimen dimensions and avoids the processing and sectioning limitations of light and transmission electron microscopic procedures. For these reasons the SEM is ideally suited for analyses of bone, a rigid tissue whose surface topography and internal architecture accurately reflect the developmental, metabolic and mechanical influences exerted upon it. Furthermore, SEM photomicrographs are compatible with devices for quantification, mathematical manipulation and graphic reconstruction of the image. Features of a photo may be traced with a stylus on the electromagnetically activated surface of a data digitizer, which converts the outlined path to x and y axis coordinates. Interfaced with a programmed calculator these data undergo algebraic and geometrical computation and may be stored for statistical analyses. Alternatively, stereopairs of micrograph transparencies may be utilized in micro-stereophotogrammetric procedures in which x, y and z axis coordinates are generated for selected morphologic points. Our research concerns spatiotemporal interrelationships of primate craniofacial growth as evidenced by changes in the skeletal gross morphology and microanatomy of the orbital region, jaws and teeth during their growth and development. Applications of SEM and digitization techniques to these studies and an evaluation of the derived data will be presented.

  2. Diagnostic applications of scanning electron microscopy and microanalysis in pathology.

    PubMed

    Abraham, J L

    1979-08-01

    Microanalytical technology developed within the last decade provides important information in diagnostic pathology. Scanning electron microscopy, including backscattered electron imaging and energy dispersive X-ray analysis should become at least as valuable as polarized light microscopy, histochemistry and conventional transmission electron microscopy. Other as yet less available techniques such as the ion microprobe and laser Raman microprobe are also valuable. The pathologist should consider the use of microanalytic techniques in any disease process in which endogenous or exogenous materials may be present in the tissues, in the same manner in which one would perform stains for microorganisms. Cases are presented illustrating the tissue preparation and results of scanning electron microscopy and energy dispersive X-ray analysis in diagnosis.

  3. Direct observations of atomic diffusion by scanning transmission electron microscopy

    PubMed Central

    Isaacson, M.; Kopf, D.; Utlaut, M.; Parker, N. W.; Crewe, A. V.

    1977-01-01

    The feasibility of using a high-resolution scanning transmission electron microscope to study the diffusion of heavy atoms on thin film substrates of low atomic number has been investigated. We have shown that it is possible to visualize the diffusion of individual uranium atoms adsorbed to thin carbon film substrates and that the observed motion of the atoms does not appear to be induced by the incident electron beam. Images PMID:16592396

  4. Scanning electron microscope facility for examination of radioactive materials

    SciTech Connect

    Gibson, J.R.; Braski, D.N.

    1985-02-01

    An AMRAY model 1200B scanning electron microscope was modified to permit remote examination of radioactive specimens. Features of the modification include pneumatic vibration isolation of the column, motorized stage controls, improvements for monitoring vacuum, and a system for changing filaments without entering the hot cell.

  5. Microstress contrast in scanning electron acoustic microscopy of ceramics

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Qian, Menglu

    1991-01-01

    A mathematical model of image contrast in scanning electron acoustic microscopy (SEAM) due to the effect of residual stresses in materials is presented. It is found that in regions near the ends of the radial cracks induced by Vickers indentation the SEAM micrographs reveal a rather large variation of the acoustic output signal.

  6. Preparation of Articular Cartilage Specimens for Scanning Electron Microscopy.

    PubMed

    Stupina, T A

    2016-08-01

    We developed and adapted a technology for preparation of articular cartilage specimens for scanning electron microscopy. The method includes prefixation processing, fixation, washing, and dehydration of articular cartilage specimens with subsequent treatment in camphene and air-drying. The technological result consists in prevention of deformation of the articular cartilage structures. The method is simpler and cheaper than the known technologies.

  7. [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.

  8. High-resolution low-dose scanning transmission electron microscopy.

    PubMed

    Buban, James P; Ramasse, Quentin; Gipson, Bryant; Browning, Nigel D; Stahlberg, Henning

    2010-01-01

    During the past two decades instrumentation in scanning transmission electron microscopy (STEM) has pushed toward higher intensity electron probes to increase the signal-to-noise ratio of recorded images. While this is suitable for robust specimens, biological specimens require a much reduced electron dose for high-resolution imaging. We describe here protocols for low-dose STEM image recording with a conventional field-emission gun STEM, while maintaining the high-resolution capability of the instrument. Our findings show that a combination of reduced pixel dwell time and reduced gun current can achieve radiation doses comparable to low-dose TEM.

  9. Low voltage scanning electron microscopy of interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Blake, D. F.; Bunch, T. E.; Reilly, T. W.; Brownlee, D. E.

    1987-01-01

    The resolution of available low-voltage SEM (LVSEM) models used in the characterization of interplanetary dust particles (IDPs) is limited by a number of factors including energy spread in the electron source, beam brightness, scanning electron detector geometry, and various lens aberrations. This paper describes an improved model of LVSEM which offers an increased resolution at low voltage. The improvements include a cold cathode FE source which has an extremely low inherent energy spread and high brightness, a second condenser lens to converge the beam and maintain an optimum aperture half-angle, and a detector optimized for low-voltage scanning-electron collection. To reduce lens aberrations, the specimen is immersed in the objective lens field. The features of several IDP samples observed using the images obtained with this LVSEM model are described.

  10. Development of scanning electron and x-ray microscope

    SciTech Connect

    Matsumura, Tomokazu Hirano, Tomohiko Suyama, Motohiro

    2016-01-28

    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 soft materials. The resolutions of SEM and X-ray modes are 50 nm and 100 nm, respectively, at the electron energy of 7 keV.

  11. Millimeter-wave electronically scanned reflectarray optimization and analysis

    NASA Astrophysics Data System (ADS)

    Hedden, Abigail S.; Dietlein, Charles R.; Wikner, David A.

    2012-06-01

    The development of millimeter-wave scanning reflectarrays and phased arrays provides an important path to enabling electronic scanning capabilities at high frequencies. This technology could be used to eliminate the mechanical scanners that are currently used with radar imaging systems. In this work, we analyze properties of wafer-scale two-dimensional rectangular lattice arrays that can be used with a confocal imager for 220 GHz electronic scanning of meter-sized fields of regard at 50 m. Applications include covert imaging of hidden anomalies. We examine tradeoffs between overall system size and array complexity and analyze properties of reflectarrays compatible with a system design that was chosen based on these considerations. The effects of phase quantization are considered in detail for arrays with 1- and 2- bit phase shifters and the results are compared in terms of impacts to image quality. Beam pointing accuracy, main beam energy fraction, and the number and intensity of quantization lobes that appear over the scan ranges of interest are compared. Our results indicate that arrays with 1- and 2-bit phase quantization achieve similar main beam energy efficiencies over the desired scan range. Without restricting the scan range, 1-bit phase quantization is insufficient, resulting in maximum errors that are comparable to the required minimum scan angle. Two-bit phase quantization is preferable, resulting in pointing angle errors of at most 15 % of the diffraction-limited beam-size. Both 1- and 2-bit phase quantization cases result in lobes appearing above our threshold, indicating that spurious returns are a problem that will require further attention.

  12. Scanning electron microscopy of the endometrium during the secretory phase.

    PubMed Central

    Motta, P M; Andrews, P M

    1976-01-01

    Scanning electron microscopy was used to study the surface morphology of the rabbit endometrium during the secretory phase of the oestrous cycle. The free surfaces of ciliated and of inactive active secretory cells are described. Changes in secretory cell surface morphology resulting from accumulation and secretion of material involve the apparent retraction of microvilli and the formation of one or more bulbous protrusions of the cell's apical surface. These protrusions may be relatively smooth surfaced or exhibit long slender micro-extensions. The protrusions grow in size and are eventually pinched off. Loss of the bulbous protrusions often leaves behind crater-like invaginations of the cell's surface. Secretory cells adjacent to the endometrial glands are the first to exhibit signs of mucin accumulation and secretion. The single cilium of a secretory cell is not apparently affected by the secretory process. Signs of ciliated and secretory cell degeneration, and possible sloughing, are also described. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 PMID:1033932

  13. 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.

  14. Scanning moiré fringe imaging by scanning transmission electron microscopy.

    PubMed

    Su, Dong; Zhu, Yimei

    2010-02-01

    A type of artificial contrast found in annular dark-field imaging is generated by spatial interference between the scanning grating of the electron beam and the specimen atomic lattice. The contrast is analogous to moiré fringes observed in conventional transmission electron microscopy. We propose using this scanning interference for retrieving information about the atomic lattice structure at medium magnifications. Compared with the STEM atomic imaging at high magnifications, this approach might have several advantages including easy observation of lattice discontinuities and reduction of image degradation from carbon contamination and beam damage. Application of the technique to reveal the Burgers vector of misfit dislocations at the interface of epitaxial films is demonstrated and its potential for studying strain fields is discussed.

  15. Influence of mechanical noise inside a scanning electron microscope.

    PubMed

    de Faria, Marcelo Gaudenzi; Haddab, Yassine; Le Gorrec, Yann; Lutz, Philippe

    2015-04-01

    The scanning electron microscope is becoming a popular tool to perform tasks that require positioning, manipulation, characterization, and assembly of micro-components. However, some of these applications require a higher level of performance with respect to dynamics and precision of positioning. One limiting factor is the presence of unidentified noises and disturbances. This work aims to study the influence of mechanical disturbances generated by the environment and by the microscope, identifying how these can affect elements in the vacuum chamber. To achieve this objective, a dedicated setup, including a high-resolution vibrometer, was built inside the microscope. This work led to the identification and quantification of main disturbances and noise sources acting on a scanning electron microscope. Furthermore, the effects of external acoustic excitations were analysed. Potential applications of these results include noise compensation and real-time control for high accuracy tasks.

  16. Influence of mechanical noise inside a scanning electron microscope

    SciTech Connect

    Gaudenzi de Faria, Marcelo; Haddab, Yassine Le Gorrec, Yann; Lutz, Philippe

    2015-04-15

    The scanning electron microscope is becoming a popular tool to perform tasks that require positioning, manipulation, characterization, and assembly of micro-components. However, some of these applications require a higher level of performance with respect to dynamics and precision of positioning. One limiting factor is the presence of unidentified noises and disturbances. This work aims to study the influence of mechanical disturbances generated by the environment and by the microscope, identifying how these can affect elements in the vacuum chamber. To achieve this objective, a dedicated setup, including a high-resolution vibrometer, was built inside the microscope. This work led to the identification and quantification of main disturbances and noise sources acting on a scanning electron microscope. Furthermore, the effects of external acoustic excitations were analysed. Potential applications of these results include noise compensation and real-time control for high accuracy tasks.

  17. Composition quantification of electron-transparent samples by backscattered electron imaging in scanning electron microscopy.

    PubMed

    Müller, E; Gerthsen, D

    2017-02-01

    The contrast of backscattered electron (BSE) images in scanning electron microscopy (SEM) depends on material parameters which can be exploited for composition quantification if some information on the material system is available. As an example, the In-concentration in thin InxGa1-xAs layers embedded in a GaAs matrix is analyzed in this work. The spatial resolution of the technique is improved by using thin electron-transparent specimens instead of bulk samples. Although the BSEs are detected in a comparably small angular range by an annular semiconductor detector, the image intensity can be evaluated to determine the composition and local thickness of the specimen. The measured intensities are calibrated within one single image to eliminate the influence of the detection and amplification system. Quantification is performed by comparison of experimental and calculated data. Instead of using time-consuming Monte-Carlo simulations, an analytical model is applied for BSE-intensity calculations which considers single electron scattering and electron diffusion.

  18. Scanning electron microscope studies of human metaphase chromosomes.

    PubMed

    Shemilt, L A; Estandarte, A K C; Yusuf, M; Robinson, I K

    2014-03-06

    Scanning electron microscopy (SEM) is used to evaluate potential chromosome preparations and staining methods for application in high-resolution three-dimensional X-ray imaging. Our starting point is optical fluorescence microscopy, the standard method for chromosomes, which only gives structural detail at the 200 nm scale. In principle, with suitable sample preparation protocols, including contrast enhancing staining, the surface structure of the chromosomes can be viewed at the 1 nm level by SEM. Here, we evaluate a heavy metal nucleic-acid-specific stain, which gives strong contrast in the backscattered electron signal. This study uses SEM to examine chromosomes prepared in different ways to establish a sample preparation protocol for X-rays. Secondary electron and backscattered electron signals are compared to evaluate the effectiveness of platinum-based stains used to enhance the contrast.

  19. Cryo-scanning transmission electron tomography of vitrified cells.

    PubMed

    Wolf, Sharon Grayer; Houben, Lothar; Elbaum, Michael

    2014-04-01

    Cryo-electron tomography (CET) of fully hydrated, vitrified biological specimens has emerged as a vital tool for biological research. For cellular studies, the conventional imaging modality of transmission electron microscopy places stringent constraints on sample thickness because of its dependence on phase coherence for contrast generation. Here we demonstrate the feasibility of using scanning transmission electron microscopy for cryo-tomography of unstained vitrified specimens (CSTET). We compare CSTET and CET for the imaging of whole bacteria and human tissue culture cells, finding favorable contrast and detail in the CSTET reconstructions. Particularly at high sample tilts, the CSTET signals contain more informative data than energy-filtered CET phase contrast images, resulting in improved depth resolution. Careful control over dose delivery permits relatively high cumulative exposures before the onset of observable beam damage. The increase in acceptable specimen thickness broadens the applicability of electron cryo-tomography.

  20. Scanning electron microscopy of clays and clay minerals

    USGS Publications Warehouse

    Bohor, B.F.; Hughes, R.E.

    1971-01-01

    The scanning electron microscope (SEM) proves to be ideally suited for studying the configuration, texture, and fabric of clay samples. Growth mechanics of crystalline units-interpenetration and interlocking of crystallites, crystal habits, twinning, helical growth, and topotaxis-also are uniquely revealed by the SEM. Authigenic kaolins make up the bulk of the examples because their larger crystallite size, better crystallinity, and open texture make them more suited to examination by the SEM than most other clay mineral types. ?? 1971.

  1. Scanning electron microscopic study on Toxascaris transfuga (Rudolphi, 1819) (Nematoda).

    PubMed

    Tenora, F; Mituch, J; Hovorka, I

    1989-01-01

    The authors present original observations on the species Toxascaris transfuga obtained by means of scanning electron microscopy. Attention was paid to the structure of head end, morphology of papillae of the head and abdominal end, specific morphological traits of cloacae edges and morphology of the egg surface. Presented are morphological criteria which apparently differentiate the species T. transfuga from T. leonina (Linstow, 1902). T. transfuga and T. multipapillata Kreis, 1938 seem to be conspecific.

  2. Free-standing graphene by scanning transmission electron microscopy.

    PubMed

    Song, F Q; Li, Z Y; Wang, Z W; He, L; Han, M; Wang, G H

    2010-11-01

    Free-standing graphene sheets have been imaged by scanning transmission electron microscopy (STEM). We show that the discrete numbers of graphene layers enable an accurate calibration of STEM intensity to be performed over an extended thickness and with single atomic layer sensitivity. We have applied this calibration to carbon nanoparticles with complex structures. This leads to the direct and accurate measurement of the electron mean free path. Here, we demonstrate potentials using graphene sheets as a novel mass standard in STEM-based mass spectrometry.

  3. Scanning transmission electron microscopy: Albert Crewe's vision and beyond.

    PubMed

    Krivanek, Ondrej L; Chisholm, Matthew F; Murfitt, Matthew F; Dellby, Niklas

    2012-12-01

    Some four decades were needed to catch up with the vision that Albert Crewe and his group had for the scanning transmission electron microscope (STEM) in the nineteen sixties and seventies: attaining 0.5Å resolution, and identifying single atoms spectroscopically. With these goals now attained, STEM developments are turning toward new directions, such as rapid atomic resolution imaging and exploring atomic bonding and electronic properties of samples at atomic resolution. The accomplishments and the future challenges are reviewed and illustrated with practical examples.

  4. Environmental scanning electron microscopy gold immunolabeling in cell biology.

    PubMed

    Rosso, Francesco; Papale, Ferdinando; Barbarisi, Alfonso

    2013-01-01

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

  5. Rapidly and continuously frequency-scanning opto-electronic oscillator.

    PubMed

    Cen, Qizhuang; Dai, Yitang; Yin, Feifei; Zhou, Yue; Li, Jianqiang; Dai, Jian; Yu, Lan; Xu, Kun

    2017-01-23

    An opto-electronic oscillator (OEO) scheme which operates at "chirp oscillation" mode and generates low-phase-noise, frequency-swept microwave is proposed and experimentally demonstrated. This frequency-swept OEO is achieved by embedding a rapidly frequency-scanning microwave filter in an opto-electronic cavity. The filter has fixed passband while its center frequency scans rapidly and periodically at cavity round-trip time, covering a large frequency range (~GHz). Experimentally, the generated frequency-swept microwave is linear frequency-modulated continuous wave (FMCW) which centers at 7 GHz with 1-GHz bandwidth. Its instantaneous frequency varies linearly from 6.5 GHz to 7.5 GHz, back and forth, in a period of 12.8 μs, resulting in a frequency scanning rate of ~156 MHz/μs. The single-side-band (SSB) noise of the generated FMCW is -104 dBc/Hz at 10 kHz offset frequency, which is much lower than that from a commercial electronic arbitrary waveform generator (E-AWG). Improvement as large as 23 dB is experimentally reported.

  6. Response function and optimum configuration of semiconductor backscattered-electron detectors for scanning electron microscopes

    SciTech Connect

    Rau, E. I.; Orlikovskiy, N. A.; Ivanova, E. S.

    2012-06-15

    A new highly efficient design for semiconductor detectors of intermediate-energy electrons (1-50 keV) for application in scanning electron microscopes is proposed. Calculations of the response function of advanced detectors and control experiments show that the efficiency of the developed devices increases on average twofold, which is a significant positive factor in the operation of modern electron microscopes in the mode of low currents and at low primary electron energies.

  7. Simulation and Characterization of a Miniaturized Scanning Electron Microscope

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  8. Microbial Nanowire Electronic Structure Probed by Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Veazey, Joshua P.; Lampa-Pastirk, Sanela; Reguera, Gemma; Tessmer, Stuart H.

    2010-03-01

    Complex molecules produced by living organisms provide laboratories for interesting physical properties. The study of such interesting physics, likewise, gives new insight into intriguing biological processes. We have studied the pilus nanowires expressed by the bacterium, Geobacter sulfurreducens, using high resolution scanning tunneling microscopy (STM). G. sulfurreducens is a metal reducing bacterium that has evolved electrically conductive pili to efficiently transfer electrons across large distances.footnotetextG. Reguera, K.D. McCarthy, T. Mehta, J.S. Nicoll, M.T. Tuominen, and D.R. Lovley, Nature 435, 1098 (2005) Here we employ the electronic sensitivity of STM to resolve the molecular substructure and the local electronic density of states (LDOS) along the nanowire, in an effort to elucidate the mechanism of conduction. We observe LDOS dependent upon the location of the tip above the nanowire.

  9. In situ laser processing in a scanning electron microscope

    SciTech Connect

    Roberts, Nicholas; Fowlkes, Jason Davidson; Rack, Prof. Philip; Moore, Tom; Magel, Greg; Hartfield, Cheryl

    2012-01-01

    Laser delivery probes using multimode fiber optic delivery and bulk focusing optics have been constructed and used for performing materials processing experiments within scanning electron microscope/focused ion beam instruments. Controlling the current driving a 915-nm semiconductor diode laser module enables continuous or pulsed operation down to sub-microsecond durations, and with spot sizes on the order of 50 {micro}m diameter, achieving irradiances at a sample surface exceeding 1 MW/cm{sup 2}. Localized laser heating has been used to demonstrate laser chemical vapor deposition of Pt, surface melting of silicon, enhanced purity, and resistivity via laser annealing of Au deposits formed by electron beam induced deposition, and in situ secondary electron imaging of laser induced dewetting of Au metal films on SiO{sub x}.

  10. In situ laser processing in a scanning electron microscope

    SciTech Connect

    Roberts, Nicholas A.; Magel, Gregory A.; Hartfield, Cheryl D.; Moore, Thomas M.; Fowlkes, Jason D.; Rack, Philip D.

    2012-07-15

    Laser delivery probes using multimode fiber optic delivery and bulk focusing optics have been constructed and used for performing materials processing experiments within scanning electron microscope/focused ion beam instruments. Controlling the current driving a 915-nm semiconductor diode laser module enables continuous or pulsed operation down to sub-microsecond durations, and with spot sizes on the order of 50 {mu}m diameter, achieving irradiances at a sample surface exceeding 1 MW/cm{sup 2}. Localized laser heating has been used to demonstrate laser chemical vapor deposition of Pt, surface melting of silicon, enhanced purity, and resistivity via laser annealing of Au deposits formed by electron beam induced deposition, and in situ secondary electron imaging of laser induced dewetting of Au metal films on SiO{sub x}.

  11. Effects of instrument imperfections on quantitative scanning transmission electron microscopy.

    PubMed

    Krause, Florian F; Schowalter, Marco; Grieb, Tim; Müller-Caspary, Knut; Mehrtens, Thorsten; Rosenauer, Andreas

    2016-02-01

    Several instrumental imperfections of transmission electron microscopes are characterized and their effects on the results of quantitative scanning electron microscopy (STEM) are investigated and quantified using simulations. Methods to either avoid influences of these imperfections during acquisition or to include them in reference calculations are proposed. Particularly, distortions inflicted on the diffraction pattern by an image-aberration corrector can cause severe errors of more than 20% if not accounted for. A procedure for their measurement is proposed here. Furthermore, afterglow phenomena and nonlinear behavior of the detector itself can lead to incorrect normalization of measured intensities. Single electrons accidentally impinging on the detector are another source of error but can also be exploited for threshold-less calibration of STEM images to absolute dose, incident beam current determination and measurement of the detector sensitivity.

  12. Chromosome observation by scanning electron microscopy using ionic liquid.

    PubMed

    Dwiranti, Astari; Lin, Linyen; Mochizuki, Eiko; Kuwabata, Susumu; Takaoka, Akio; Uchiyama, Susumu; Fukui, Kiichi

    2012-08-01

    Electron microscopy has been used to visualize chromosome since it has high resolution and magnification. However, biological samples need to be dehydrated and coated with metal or carbon before observation. Ionic liquid is a class of ionic solvent that possesses advantageous properties of current interest in a variety of interdisciplinary areas of science. By using ionic liquid, biological samples need not be dehydrated or metal-coated, because ionic liquid behaves as the electronically conducting material for electron microscopy. The authors have investigated chromosome using ionic liquid in conjunction with electron microscopy and evaluated the factors that affect chromosome visualization. Experimental conditions used in the previous studies were further optimized. As a result, prewarmed, well-mixed, and low concentration (0.5∼1.0%) ionic liquid provides well-contrasted images, especially when the more hydrophilic and the higher purity ionic liquid is used. Image contrast and resolution are enhanced by the combination of ionic liquid and platinum blue staining, the use of an indium tin oxide membrane, osmium tetroxide-coated coverslip, or aluminum foil as substrate, and the adjustment of electron acceleration voltage. The authors conclude that the ionic-liquid method is useful for the visualization of chromosome by scanning electron microscopy without dehydration or metal coating.

  13. Scanning SQUID microscopy with single electron spin sensitivity

    NASA Astrophysics Data System (ADS)

    Vasyukov, Denis

    2014-03-01

    Superconducting interference devices (SQUIDs) have been traditionally used for studying fundamental properties of magnetic materials and superconductors. Although widely used in scanning magnetic microscopy, their progress towards detection of small magnetic moments was stagnating of late due to limitations imposed by conventional designs of planar SQUIDs and contemporary lithography techniques, restricting sample-to-sensor distance smaller than ~ 0.5 micron and SQUIDs diameters smaller than ~ 200 nm. These limitations were overcome by the invention of a SQUID-on-tip device, subsequent realization of a SQUID-on-tip microscope, and by creation of an ultra-small sensor with spatial resolution of 20 nm and sensitivity to a single electron spin per 1 Hz bandwidth. In this talk I will describe the principles of scanning SQUID magnetometry, its applications to study superconductors and its potential for magnetic nano-scale imaging of novel materials.

  14. A new apparatus for electron tomography in the scanning electron microscope

    SciTech Connect

    Morandi, V. Maccagnani, P.; Masini, L.; Migliori, A.; Ortolani, L.; Pezza, A.; Del Marro, M.; Pallocca, G.; Vinciguerra, P.; Rossi, M.; Ferroni, M.; Sberveglieri, G.; Vittori-Antisari, M.

    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 required by the tomographic workflow. A Si-based electron detector and an eucentric-rotation specimen holder have been specifically developed for the purpose.

  15. Controller for the Electronically Scanned Thinned Array Radiometer (ESTAR) instrument

    NASA Technical Reports Server (NTRS)

    Zomberg, Brian G.; Chren, William A., Jr.

    1994-01-01

    A prototype controller for the ESTAR (electronically scanned thinned array radiometer) instrument has been designed and tested. It manages the operation of the digital data subsystem (DDS) and its communication with the Small Explorer data system (SEDS). Among the data processing tasks that it coordinates are FEM data acquisition, noise removal, phase alignment and correlation. Its control functions include instrument calibration and testing of two critical subsystems, the output data formatter and Walsh function generator. It is implemented in a Xilinx XC3064PC84-100 field programmable gate array (FPGA) and has a maximum clocking frequency of 10 MHz.

  16. [Scanning electron microscopy of heat-damaged bone tissue].

    PubMed

    Harsanyl, L

    1977-02-01

    Parts of diaphyses of bones were exposed to high temperature of 200-1300 degrees C. Damage to the bone tissue caused by the heat was investigated. The scanning electron microscopic picture seems to be characteristic of the temperature applied. When the bones heated to the high temperature of 700 degrees C characteristic changes appear on the periostal surface, higher temperatura on the other hand causes damage to the compact bone tissue and can be observed on the fracture-surface. Author stresses the importance of this technique in the legal medicine and anthropology.

  17. Dynamic-pressure measurements using an electronically scanned pressure module

    NASA Technical Reports Server (NTRS)

    Chapin, W. G.

    1983-01-01

    Frequency response was measured for different lengths and diameters of tubing between a sinusoidal pressure source and a pressure sensing module from an electronically scanned pressure measuring system. Measurements were made for straight runs of both steel and vinyl tubing. For steel tubing, measured results are compared with results calculated by using equations developed by Tijdeman and Bergh. Measurements were also made with a bend in the vinyl tubing at the module. In addition, measurements were made with two coils placed in the tubing near the middle of the run.

  18. Adaptive noise Wiener filter for scanning electron microscope imaging system.

    PubMed

    Sim, K S; Teh, V; Nia, M E

    2016-01-01

    Noise on scanning electron microscope (SEM) images is studied. Gaussian noise is the most common type of noise in SEM image. We developed a new noise reduction filter based on the Wiener filter. We compared the performance of this new filter namely adaptive noise Wiener (ANW) filter, with four common existing filters as well as average filter, median filter, Gaussian smoothing filter and the Wiener filter. Based on the experiments results the proposed new filter has better performance on different noise variance comparing to the other existing noise removal filters in the experiments.

  19. Controller for the Electronically Scanned Thinned Array Radiometer (ESTAR) instrument

    NASA Astrophysics Data System (ADS)

    Zomberg, Brian G.; Chren, William A., Jr.

    1994-06-01

    A prototype controller for the ESTAR (electronically scanned thinned array radiometer) instrument has been designed and tested. It manages the operation of the digital data subsystem (DDS) and its communication with the Small Explorer data system (SEDS). Among the data processing tasks that it coordinates are FEM data acquisition, noise removal, phase alignment and correlation. Its control functions include instrument calibration and testing of two critical subsystems, the output data formatter and Walsh function generator. It is implemented in a Xilinx XC3064PC84-100 field programmable gate array (FPGA) and has a maximum clocking frequency of 10 MHz.

  20. Measurement of dihedral angles by scanning electron microscopy.

    NASA Technical Reports Server (NTRS)

    Achutaramayya, G.; Scott, W. D.

    1973-01-01

    The extension of Hoover's (1971) technique to the case of dihedral-angle measurement is described. Dihedral angles are often determined by interferometry on thermally grooved grain boundaries to obtain information on relative interfacial energies. In the technique considered the measured angles approach the true angles as the tilt angle approaches 90 deg. It is pointed out that the scanning electron microscopy method provides a means of seeing the real root of a groove at a lateral magnification which is higher than that obtainable with interferometry.

  1. Characteristics of different frequency ranges in scanning electron microscope images

    SciTech Connect

    Sim, K. S. Nia, M. E.; Tan, T. L.; Tso, C. P.; Ee, C. S.

    2015-07-22

    We demonstrate a new approach to characterize the frequency range in general scanning electron microscope (SEM) images. First, pure frequency images are generated from low frequency to high frequency, and then, the magnification of each type of frequency image is implemented. By comparing the edge percentage of the SEM image to the self-generated frequency images, we can define the frequency ranges of the SEM images. Characterization of frequency ranges of SEM images benefits further processing and analysis of those SEM images, such as in noise filtering and contrast enhancement.

  2. [Using of scanning electron microscopy for detection of gunshot residue].

    PubMed

    Havel, J; Vajtr, D; Starý, V; Vrána, J; Zelenka, K; Adámek, T

    2006-07-01

    Scanning electron microscope improves the possibility of investigation of surroundings near of gunshot wounds in forensic medicine, it is the next subsequent method for differentiating of area of entrance and exit wound, supplemental method for determination of firing distance, permit of detection (GSR) on the hand of shooter and ensured describing of samples and their stored. Detection of GSR provides many information about composition of bullet and primer. Authors are demonstrating the possibility of detection of GSR on experimental shooting to the krupon (pigs' skin) in different situation (such as in a room and in outside area) and using of different weapon (hand gun CZ No.75 and machine gun No.58).

  3. MicroDiffraction in the Scanning Electron Microscope (SEM)

    SciTech Connect

    Goehner, R.P.; Michael, J.R.; Schlienger, M.E.

    1997-12-31

    The identification of crystallographic phases in the scanning electron microscope (SEM) has been limited by the lack of a simple way to obtain electron diffraction data of an unknown while observing the micro structure of the specimen. With the development of Charge Coupled Device (CCD) based detectors, backscattered electron Kikuchi patterns (BEKP), alternately referred to as electron backscattered diffraction patterns (EBSP), can be easily collected. Previously, BEKP has been limited to crystallographic orientation studies due to the poor pattern quality collected with video rate detector systems. With CCD detectors, a typical BEKP can now be acquired from a micron or sub-micron-sized crystal using an exposure time of 1-10 seconds with an accelerating voltage of 10-40 kV and a beam current as low as 0.1 nA. Crystallographic phase analysis using BEKP is unique in that the properly equipped SEM permits high magnification images, BEKP`s, and elemental information to be collected from bulk specimens. BEKP in the SEM has numerous advantages over other electron microscopy crystallographic techniques. The large angular view ( 70 degrees) provided by BEKP and the lack of difficult specimen preparation are distinct advantages of the technique. No sample preparation beyond what is commonly used for SEM specimens is required for BEKP.

  4. Scanning electron microscopy of primate chorionic villi following ultrasonic microdissection.

    PubMed

    King, B F

    1991-01-01

    Villi from human, macaque and baboon placentae were subjected to ultrasonication after prolonged osmication, and examined by scanning electron microscopy. The technique was often successful in removing the overlying trophoblast and revealing expanses of the trophoblastic basal lamina, a conclusion corroborated by transmission electron microscopy. These preparations bore a remarkable similarity in appearance to microvascular cast preparations of the fetal vasculature. Relatively straight parallel tubules appeared to correspond in position to the location of fetal vessels in intermediate villi, whereas portions of the basal laminae of terminal villi were in the form of convoluted, branched cylinders similar to SEM images of fetal capillaries of terminal villi. The basal lamina did not have evidence of pores as has been described in some basal laminae.

  5. Modeling atomic-resolution scanning transmission electron microscopy images.

    PubMed

    Findlay, Scott D; Oxley, Mark P; Allen, Leslie J

    2008-02-01

    A real-space description of inelastic scattering in scanning transmission electron microscopy is derived with particular attention given to the implementation of the projected potential approximation. A hierarchy of approximations to expressions for inelastic images is presented. Emphasis is placed on the conditions that must hold in each case. The expressions that justify the most direct, visual interpretation of experimental data are also the most approximate. Therefore, caution must be exercised in selecting experimental parameters that validate the approximations needed for the analysis technique used. To make the most direct, visual interpretation of electron-energy-loss spectroscopic images from core-shell excitations requires detector improvements commensurate with those that aberration correction provides for the probe-forming lens. Such conditions can be relaxed when detailed simulations are performed as part of the analysis of experimental data.

  6. Scanning electron microscopy: preparation and imaging for SEM.

    PubMed

    Jones, Chris G

    2012-01-01

    Scanning electron microscopy (SEM) has been almost universally applied for the surface examination and characterization of both natural and man-made objects. Although an invasive technique, developments in electron microscopy over the years has given the microscopist a much clearer choice in how invasive the technique will be. With the advent of low vacuum SEM in the 1970s (The environmental cold stage, 1970) and environmental SEM in the late 1980s (J Microsc 160(pt. 1):9-19, 1989), it is now possible in some circumstances to examine samples without preparation. However, for the examination of biological tissue and cells it is still advisable to chemically fix, dehydrate, and coat samples for SEM imaging and analysis. This chapter aims to provide an overview of SEM as an imaging tool, and a general introduction to some of the methods applied for the preparation of samples.

  7. Theory and application of scanning electron acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Qian, Menglu; Chen, Ruiyi; Yost, William T.

    1992-01-01

    A three-dimensional theoretical model based on the application of the thermal conduction and Navier equations to a chopped electron beam incident on a disk specimen is used to obtain the particle displacement field in the specimen. The results lead to a consideration of the signal generation, spatial resolution, and contrast mechanisms in scanning electron acoustic microscopy (SEAM). The model suggests that the time-variant heat source produced by the beam chopping generates driving source, thermal wave, and acoustic wave displacements simultaneously in the specimen. Evidence of the correctness of the prediction is obtained from the mathematically similar problem of pulsed laser light injection into a tank of water. High speed Schlieren photographs taken following laser injection show the simultaneous evolution of thermal and acoustic waveforms. Examples of contrast reversal, stress-induced contrast, and acoustic zone contrast and resolution with SEAM are presented and explained in terms of the model features.

  8. Sample heating system for spin-polarized scanning electron microscopy.

    PubMed

    Kohashi, Teruo; Motai, Kumi

    2013-08-01

    A sample-heating system for spin-polarized scanning electron microscopy (spin SEM) has been developed and used for microscopic magnetization analysis at temperatures up to 500°C. In this system, a compact ceramic heater and a preheating operation keep the ultra-high vacuum conditions while the sample is heated during spin SEM measurement. Moreover, the secondary-electron collector, which is arranged close to the sample, was modified so that it is not damaged at high temperatures. The system was used to heat a Co(1000) single-crystal sample from room temperature up to 500°C, and the magnetic-domain structures were observed. Changes of the domain structures were observed around 220 and 400°C, and these changes are considered to be due to phase transitions of this sample.

  9. Combined Scanning Transmission Electron Microscopy Tilt- and Focal Series

    SciTech Connect

    Dahmen, Tim; Baudoin, Jean-Pierre G; Lupini, Andrew R; Kubel, Christian; Slusallek, Phillip; De Jonge, Niels

    2014-01-01

    In this study, a combined tilt- and focal series is proposed as a new recording scheme for high-angle annular dark-field scanning transmission electron microscopy (STEM) tomography. Three-dimensional (3D) data were acquired by mechanically tilting the specimen, and recording a through-focal series at each tilt direction. The sample was a whole-mount macrophage cell with embedded gold nanoparticles. The tilt focal algebraic reconstruction technique (TF-ART) is introduced as a new algorithm to reconstruct tomograms from such combined tilt- and focal series. The feasibility of TF-ART was demonstrated by 3D reconstruction of the experimental 3D data. The results were compared with a conventional STEM tilt series of a similar sample. The combined tilt- and focal series led to smaller missing wedge artifacts, and a higher axial resolution than obtained for the STEM tilt series, thus improving on one of the main issues of tilt series-based electron tomography.

  10. Simultaneous Correlative Scanning Electron and High-NA Fluorescence Microscopy

    PubMed Central

    Liv, Nalan; Zonnevylle, A. Christiaan; Narvaez, Angela C.; Effting, Andries P. J.; Voorneveld, Philip W.; Lucas, Miriam S.; Hardwick, James C.; Wepf, Roger A.; Kruit, Pieter; Hoogenboom, Jacob P.

    2013-01-01

    Correlative light and electron microscopy (CLEM) is a unique method for investigating biological structure-function relations. With CLEM protein distributions visualized in fluorescence can be mapped onto the cellular ultrastructure measured with electron microscopy. Widespread application of correlative microscopy is hampered by elaborate experimental procedures related foremost to retrieving regions of interest in both modalities and/or compromises in integrated approaches. We present a novel approach to correlative microscopy, in which a high numerical aperture epi-fluorescence microscope and a scanning electron microscope illuminate the same area of a sample at the same time. This removes the need for retrieval of regions of interest leading to a drastic reduction of inspection times and the possibility for quantitative investigations of large areas and datasets with correlative microscopy. We demonstrate Simultaneous CLEM (SCLEM) analyzing cell-cell connections and membrane protrusions in whole uncoated colon adenocarcinoma cell line cells stained for actin and cortactin with AlexaFluor488. SCLEM imaging of coverglass-mounted tissue sections with both electron-dense and fluorescence staining is also shown. PMID:23409024

  11. Contamination mitigation strategies for scanning transmission electron microscopy.

    PubMed

    Mitchell, D R G

    2015-06-01

    Modern scanning transmission electron microscopy (STEM) enables imaging and microanalysis at very high magnification. In the case of aberration-corrected STEM, atomic resolution is readily achieved. However, the electron fluxes used may be up to three orders of magnitude greater than those typically employed in conventional STEM. Since specimen contamination often increases with electron flux, specimen cleanliness is a critical factor in obtaining meaningful data when carrying out high magnification STEM. A range of different specimen cleaning methods have been applied to a variety of specimen types. The contamination rate has been measured quantitatively to assess the effectiveness of cleaning. The methods studied include: baking, cooling, plasma cleaning, beam showering and UV/ozone exposure. Of the methods tested, beam showering is rapid, experimentally convenient and very effective on a wide range of specimens. Oxidative plasma cleaning is also very effective and can be applied to specimens on carbon support films, albeit with some care. For electron beam-sensitive materials, cooling may be the method of choice. In most cases, preliminary removal of the bulk of the contamination by methods such as baking or plasma cleaning, followed by beam showering, where necessary, can result in a contamination-free specimen suitable for extended atomic scale imaging and analysis.

  12. Electronic Single Molecule Measurements with the Scanning Tunneling Microscope

    NASA Astrophysics Data System (ADS)

    Im, Jong One

    Richard Feynman said "There's plenty of room at the bottom". This inspired the techniques to improve the single molecule measurements. Since the first single molecule study was in 1961, it has been developed in various field and evolved into powerful tools to understand chemical and biological property of molecules. This thesis demonstrates electronic single molecule measurement with Scanning Tunneling Microscopy (STM) and two of applications of STM; Break Junction (BJ) and Recognition Tunneling (RT). First, the two series of carotenoid molecules with four different substituents were investigated to show how substituents relate to the conductance and molecular structure. The measured conductance by STM-BJ shows that Nitrogen induces molecular twist of phenyl distal substituents and conductivity increasing rather than Carbon. Also, the conductivity is adjustable by replacing the sort of residues at phenyl substituents. Next, amino acids and peptides were identified through STM-RT. The distribution of the intuitive features (such as amplitude or width) are mostly overlapped and gives only a little bit higher separation probability than random separation. By generating some features in frequency and cepstrum domain, the classification accuracy was dramatically increased. Because of large data size and many features, supporting vector machine (machine learning algorithm for big data) was used to identify the analyte from a data pool of all analytes RT data. The STM-RT opens a possibility of molecular sequencing in single molecule level. Similarly, carbohydrates were studied by STM-RT. Carbohydrates are difficult to read the sequence, due to their huge number of possible isomeric configurations. This study shows that STM-RT can identify not only isomers of mono-saccharides and disaccharides, but also various mono-saccharides from a data pool of eleven analytes. In addition, the binding affinity between recognition molecule and analyte was investigated by comparing with

  13. Simulations and measurements in scanning electron microscopes at low electron energy.

    PubMed

    Walker, Christopher G H; Frank, Luděk; Müllerová, Ilona

    2016-11-01

    The advent of new imaging technologies in Scanning Electron Microscopy (SEM) using low energy (0-2 keV) electrons has brought about new ways to study materials at the nanoscale. It also brings new challenges in terms of understanding electron transport at these energies. In addition, reduction in energy has brought new contrast mechanisms producing images that are sometimes difficult to interpret. This is increasing the push for simulation tools, in particular for low impact energies of electrons. The use of Monte Carlo calculations to simulate the transport of electrons in materials has been undertaken by many authors for several decades. However, inaccuracies associated with the Monte Carlo technique start to grow as the energy is reduced. This is not simply associated with inaccuracies in the knowledge of the scattering cross-sections, but is fundamental to the Monte Carlo technique itself. This is because effects due to the wave nature of the electron and the energy band structure of the target above the vacuum energy level become important and these are properties which are difficult to handle using the Monte Carlo method. In this review we briefly describe the new techniques of scanning low energy electron microscopy and then outline the problems and challenges of trying to understand and quantify the signals that are obtained. The effects of charging and spin polarised measurement are also briefly explored. SCANNING 38:802-818, 2016. © 2016 Wiley Periodicals, Inc.

  14. Creating and Probing Graphene Electron Optics with Local Scanning Probes

    NASA Astrophysics Data System (ADS)

    Stroscio, Joseph

    Ballistic propagation and the light-like dispersion of graphene charge carriers make graphene an attractive platform for optics-inspired graphene electronics where gate tunable potentials can control electron refraction and transmission. In analogy to optical wave propagation in lenses, mirrors and metamaterials, gate potentials can be used to create a negative index of refraction for Veselago lensing and Fabry-Pérot interferometers. In circular geometries, gate potentials can induce whispering gallery modes (WGM), similar to optical and acoustic whispering galleries albeit on a much smaller length scale. Klein scattering of Dirac carriers plays a central role in determining the coherent propagation of electron waves in these resonators. In this talk, I examine the probing of electron resonators in graphene confined by linear and circular gate potentials with the scanning tunneling microscope (STM). The tip in the STM tunnel junction serves both as a tunable local gate potential, and as a probe of the graphene states through tunneling spectroscopy. A combination of a back gate potential, Vg, and tip potential, Vb, creates and controls a circular pn junction that confines the WGM graphene states. The resonances are observed in two separate channels in the tunneling spectroscopy experiment: first, by directly tunneling into the state at the bias energy eVb, and, second, by tunneling from the resonance at the Fermi level as the state is gated by the tip potential. The second channel produces a fan-like set of WGM peaks, reminiscent of the fringes seen in planar geometries by transport measurements. The WGM resonances split in a small applied magnetic field, with a large energy splitting approaching the WGM spacing at 0.5 T. These results agree well with recent theory on Klein scattering in graphene electron resonators. This work is done in collaboration with Y. Zhao, J. Wyrick, F.D. Natterer, J. F. Rodriquez-Nieva, C. Lewandoswski, K. Watanabe, T. Taniguchi, N. B

  15. Electron transparent graphene windows for environmental scanning electron microscopy in liquids and dense gases.

    PubMed

    Stoll, Joshua D; Kolmakov, Andrei

    2012-12-21

    Due to its ultrahigh electron transmissivity in a wide electron energy range, molecular impermeability, high electrical conductivity and excellent mechanical stiffness, suspended graphene membranes appear to be a nearly ideal window material for in situ (in vivo) environmental electron microscopy of nano- and mesoscopic objects (including bio-medical samples) immersed in liquids and/or in dense gaseous media. In this paper, taking advantage of a small modification of the graphene transfer protocol onto metallic and SiN supporting orifices, reusable environmental cells with exchangeable graphene windows have been designed. Using colloidal gold nanoparticles (50 nm) dispersed in water as model objects for scanning electron microscopy in liquids as proof of concept, different conditions for imaging through the graphene membrane were tested. Limiting factors for electron microscopy in liquids, such as electron beam induced water radiolysis and damage of the graphene membrane at high electron doses, are discussed.

  16. A study of hydrogenated carbon fibers by scanning electron microscopy and confocal laser scanning microscopy.

    PubMed

    de la Cal, Antonio Madroñero; Aguado-Serrano, Juan; Rojas-Cervantes, Maria Luisa; Adame, Elena V Rosa; Marron, Belen Sarmiento; Rosende, Africa Castro; Nevshupa, Roman

    2009-06-01

    The hydrogen absorption process is studied in carbonaceous fibers produced from a mixture of methane and hydrogen. The absorption of the hydrogen was examined in two types of fibers, in "as-grown" state and after a process of desorption during an annealing to 1.473 K under vacuum. Later to its production process, the fibers withstand an oxidation in air to 973 K. The fibers were examined by means of scanning electron microscopy (SEM) and confocal microscopy by reflection. Differences in the behavior during the oxidation were observed between the fibers in as-grown state and those subjected to a further annealing. It could be verified that the fibers were really constituted by two different phases. In one of the phases, the storage of the hydrogen absorbed took place, whereas in the other phase there was no alteration. The process of annealing prior to the absorption of the hydrogen has an appreciable effect on the desorption rate of the hydrogen.

  17. Ultrahigh vacuum scanning electron microscope system combined with wide-movable scanning tunneling microscope

    SciTech Connect

    Kaneko, A.; Homma, Y.; Hibino, H.; Ogino, T.

    2005-08-15

    A surface analysis system has been newly developed with combination of ultrahigh vacuum scanning electron microscope (SEM) and wide-movable scanning tunneling microscope (STM). The basic performance is experimentally demonstrated. These SEM and STM images are clear enough to obtain details of surface structures. The STM unit moves horizontally over several millimeters by sliding motion of PZT actuators. The motion resolution is proved to be submicrometers. The STM tip mounted on another PZT scanner can be guided to a specific object on the sample surface during SEM observation. In the observation of a Si(111) surface rapidly cooled from high temperature, the STM tip was accurately guided to an isolated atomic step and slightly moved along it during SEM observation. The STM observation shows an asymmetry of the (7x7)-transformed region along the step between the upper and lower terraces. (7x7) bands continuously formed along the edge of terraces, while (7x7) domains distributed on the terraces slightly far from the step. These experiments show the wide-movable STM unit resolves a gap of observation area between SEM and STM and the system enables a specific object found in the SEM image to be observed easily by STM.

  18. Three-dimensional scanning transmission electron microscopy of biological specimens

    SciTech Connect

    De Jonge, Niels; Sougrat, Rachid; Northan, Brian; Pennycook, Stephen J

    2010-01-01

    A three-dimensional (3D) reconstruction of the cytoskeleton and a clathrin-coated pit in mammalian cells has been achieved from a focal-series of images recorded in an aberration-corrected scanning transmission electron microscope (STEM). The specimen was a metallic replica of the biological structure comprising Pt nanoparticles 2 - 3 nm in diameter, with a high stability under electron beam radiation. The 3D dataset was processed by an automated deconvolution procedure. The lateral resolution was 1.1 nm, set by pixel size. Particles differing by only 10 nm in vertical position were identified as separate objects with greater than 20% dip in contrast between them. We refer to this value as the axial resolution of the deconvolution or reconstruction, the ability to recognize two objects, which were unresolved in the original data set. The precision of the height determination was 0.2 nm. The resolution of the reconstruction is comparable to that achieved by tilt-series transmission electron microscopy (TEM). However, the focal-series method does not require mechanical tilting and is therefore much faster. 3D STEM images were also recorded of the Golgi ribbon in conventional thin sections containing 3T3 cells with a comparable axial resolution in the deconvolved data set.

  19. Arc Welders' pneumoconiosis: application of advanced scanning electron microscopy.

    PubMed

    Guidotti, T L; Abraham, J L; DeNee, P B; Smith, J R

    1978-01-01

    Study of lung tissue from necropsy of a 58-year-old arc welder with arc welders' pneumoconiosis, confirmed by history, chest radiography, and pathology, demonstrates the versatility and usefulness of new techniques in scanning electron microscopy (SEM). Secondary electron imaging, the most familiar SEM mode, showed heavy cellular infiltrates in alveoli, the interstitium, and within the interstices of loose whorled fibrotic nodules. Backscattered electron imaging, in which contrast is proportional to elemental atomic number, revealed intracellular metal particles not otherwise visible. Microprobe analysis, energy-dispersive x-ray spectrometry, mapped elemeental iron over the particle image and identified traces of silicon in the whorled nodules. Arc welders' pneumoconiosis appears to be more than a benign siderosis resulting from particulate iron deposition. Simultaneous exposure to other components of welding fumes may alter the pathologic picture, inducing a more complicated fibrotic reaction. The more recently developed advanced techniques of SEM are well suited to the study of pneumoconioses and other problems of heterogenous tissue and mixed chemical systems.

  20. Factors influencing quantitative liquid (scanning) transmission electron microscopy

    SciTech Connect

    Abellan Baeza, Patricia; Woehl, Taylor J.; Parent, Lucas R.; Browning, Nigel D.; Evans, James E.; Arslan, Ilke

    2014-04-15

    One of the experimental challenges in the study of nanomaterials in liquids in the (scanning) transmission electron microscope ((S)TEM) is gaining quantitative information. A successful experiment in the fluid stage will depend upon the ability to plan for sensitive factors such as the electron dose applied, imaging mode, acceleration voltage, beam-induced solution chemistry changes, and the specifics of solution reactivity. In this paper, we make use of a visual approach to show the extent of damage of different instrumental and experimental factors in liquid samples imaged in the (S)TEM. Previous results as well as new insights are presented to create an overview of beam-sample interactions identified for changing imaging and experimental conditions. This work establishes procedures to understand the effect of the electron beam on a solution, provides information to allow for a deliberate choice of the optimal experimental conditions to enable quantification, and identifies the experimental factors that require further analysis for achieving fully quantitative results in the liquid (S)TEM.

  1. Three-dimensional scanning transmission electron microscopy of biological specimens.

    PubMed

    de Jonge, Niels; Sougrat, Rachid; Northan, Brian M; Pennycook, Stephen J

    2010-02-01

    A three-dimensional (3D) reconstruction of the cytoskeleton and a clathrin-coated pit in mammalian cells has been achieved from a focal-series of images recorded in an aberration-corrected scanning transmission electron microscope (STEM). The specimen was a metallic replica of the biological structure comprising Pt nanoparticles 2-3 nm in diameter, with a high stability under electron beam radiation. The 3D dataset was processed by an automated deconvolution procedure. The lateral resolution was 1.1 nm, set by pixel size. Particles differing by only 10 nm in vertical position were identified as separate objects with greater than 20% dip in contrast between them. We refer to this value as the axial resolution of the deconvolution or reconstruction, the ability to recognize two objects, which were unresolved in the original dataset. The resolution of the reconstruction is comparable to that achieved by tilt-series transmission electron microscopy. However, the focal-series method does not require mechanical tilting and is therefore much faster. 3D STEM images were also recorded of the Golgi ribbon in conventional thin sections containing 3T3 cells with a comparable axial resolution in the deconvolved dataset.

  2. Scanning electron microscopic observations of Anopheles albimanus (Diptera: Culicidae) eggs.

    PubMed

    Rodriguez, M H; Chavez, B; Orozco, A; Loyola, E G; Martinez-Palomo, A

    1992-05-01

    To investigate the existence of subspecies of Anopheles albimanus Wiedeman in southern Mexico, the egg morphology of specimens obtained from several field populations and from insectary-adapted colonies of uniform pupal phenotype was examined. Scanning electron microscopic observations have shown that the eggs of An. albimanus are polymorphic in respect to the size and shape of their floats, but not in their ornamentation. Four types of eggs were found. Differences in the proportion of the various morphological types were statistically significant, although proportions of egg types were variable among individuals within the same population. These observations are suggestive of distinctive populations and warrant further studies using more sensitive methods to investigate sibling species in An. albimanus sensu lato.

  3. An improved visual tracking method in scanning electron microscope.

    PubMed

    Ru, Changhai; Zhang, Yong; Huang, Haibo; Chen, Tao

    2012-06-01

    Since their invention, nanomanipulation systems in scanning electron microscopes (SEMs) have provided researchers with an increasing ability to interact with objects at the nanoscale. However, most nanomanipulators that are capable of generating nanometer displacement operate in an open-loop without suitable feedback mechanisms. In this article, a robust and effective tracking framework for visual servoing applications is presented inside an SEM to achieve more precise tracking manipulation and measurement. A subpixel template matching tracking algorithm based on contour models in the SEM has been developed to improve the tracking accuracy. A feed-forward controller is integrated into the control system to improve the response time. Experimental results demonstrate that a subpixel tracking accuracy is realized. Furthermore, the robustness against clutter can be achieved even in a challenging tracking environment.

  4. Scanning electron microscopy of human cortical bone failure surfaces.

    PubMed

    Braidotti, P; Branca, F P; Stagni, L

    1997-02-01

    Undecalcified samples extracted from human femoral shafts are fractured by bending and the fracture surfaces are examined with a scanning electron microscope (SEM). The investigation is performed on both dry and wet (hydrated with a saline solution) specimens. SEM micrographs show patterns in many respects similar to those observed in fractography studies of laminated fiber-reinforced synthetic composites. In particular, dry and wet samples behave like brittle and ductile matrix laminates, respectively. An analysis carried out on the basis of the mechanisms that dominate the fracture process of laminates shows that a reasonable cortical bone model is that of a laminated composite material whose matrix is composed of extracellular noncollagenous calcified proteins, and the reinforcement is constituted by the calcified collagen fiber system.

  5. Moessbauer spectroscopy and scanning electron microscopy of the Murchison meteorite

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  6. Scanning electron microscopy of ascospores of Debaryomyces and Saccharomyces.

    PubMed

    Kurtzman, C P; Smiley, M J; Baker, F L

    1975-02-28

    Ascospores from species of Debaryomyces and the Torulaspora-group of Saccharomyces were examined by scanning electron microscopy. Ornamentation on ascospores of D. hansenii varied from short to long interconnected ridges or broad based, elongated conical protuberances. A spiral rigde system was detected on the ascospores of D. marama, but wart-like protuberances occurred on those of D. cantarelli, D. castellii, D. coudertii, D. formicarius, D. phaffii, D. vanriji and D. yarrowii. Ascospores of D. halotolerans did not have protuberances and the species appears to be identical with Pichia farinosa. Wart-like protuberances also were found on ascospores of S. delbrueckii, S. microellipsodes, S. rosei, S. inconspicuus, S. fermentati, S. montanus and S. vafer, but the ascospore surface of S. pretoriensis was covered by fine ridges. Short tapered ridges covered the ascospores of S. kloeckerianus.

  7. Cylindrical Lens-Array Antenna for Wideband Electronic Scanning.

    DTIC Science & Technology

    1985-03-01

    Radome 3-21 Report No. 6546j vi WOW oft ma~ - I. Figure 3-14. Line-Feed And Housing Structure Wi thout Radome 3-20 -Zr -W -N .- .’ o - K -w .. - c - K ...I -7: 7 T Fr I~ ~ 7 .4 C 1I-7. 1,1 IF 7I1- -20 - o -----H Ii K 1 2 71 - ~ .~K14.L K ~j~jtK T ’,-. < 1 ’ IL .,, .,. I4 2 4 0 ANGL (DEGREES Fiur A-8...RD- f156 085 CYLINDRICAL LENS-RRAY ANEENNA FOR WIDEBAND ELECTRONIC 112SCAN ING(U) HAZELTINE CORP GREENL WN NY NEWAN ET AL. MAR 85 6546 F19628-80-C

  8. Detector non-uniformity in scanning transmission electron microscopy.

    PubMed

    Findlay, S D; LeBeau, J M

    2013-01-01

    A non-uniform response across scanning transmission electron microscope annular detectors has been found experimentally, but is seldom incorporated into simulations. Through case study simulations, we establish the nature and scale of the discrepancies which may arise from failing to account for detector non-uniformity. If standard detectors are used at long camera lengths such that the detector is within or near to the bright field region, we find errors in contrast of the order of 10%, sufficiently small for qualitative work but non-trivial as experiments become more quantitative. In cases where the detector has been characterized in advance, we discuss the detector response normalization and how it may be incorporated in simulations.

  9. Spatial resolution and information transfer in scanning transmission electron microscopy.

    PubMed

    Peng, Yiping; Oxley, Mark P; Lupini, Andrew R; Chisholm, Matthew F; Pennycook, Stephen J

    2008-02-01

    The relation between image resolution and information transfer is explored. It is shown that the existence of higher frequency transfer in the image is just a necessary but not sufficient condition for the achievement of higher resolution. Adopting a two-point resolution criterion, we suggest that a 10% contrast level between two features in an image should be used as a practical definition of resolution. In the context of scanning transmission electron microscopy, it is shown that the channeling effect does not have a direct connection with image resolution because sharp channeling peaks do not move with the scanning probe. Through a quantitative comparison between experimental image and simulation, a Fourier-space approach is proposed to estimate defocus and sample thickness. The effective atom size in Z-contrast imaging depends on the annular detector's inner angle. Therefore, an optimum angle exists for the highest resolution as a trade-off between reduced atom size and reduced signal with limited information transfer due to noise.

  10. Scanning electron microscopy and electron probe X-ray microanalysis (SEM-EPMA) of pink teeth

    SciTech Connect

    Ikeda, N.; Watanabe, G.; Harada, A.; Suzuki, T.

    1988-11-01

    Samples of postmortem pink teeth were investigated by scanning electron microscopy and electron probe X-ray microanalysis. Fracture surfaces of the dentin in pink teeth were noticeably rough and revealed many more smaller dentinal tubules than those of the control white teeth. Electron probe X-ray microanalysis showed that the pink teeth contained iron which seemed to be derived from blood hemoglobin. The present study confirms that under the same circumstance red coloration of teeth may occur more easily in the teeth in which the dentin is less compact and contains more dentinal tubules.

  11. Nanomaterial datasets to advance tomography in scanning transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Levin, Barnaby D. A.; Padgett, Elliot; Chen, Chien-Chun; Scott, M. C.; Xu, Rui; Theis, Wolfgang; Jiang, Yi; Yang, Yongsoo; Ophus, Colin; Zhang, Haitao; Ha, Don-Hyung; Wang, Deli; Yu, Yingchao; Abruña, Hector D.; Robinson, Richard D.; Ercius, Peter; Kourkoutis, Lena F.; Miao, Jianwei; Muller, David A.; Hovden, Robert

    2016-06-01

    Electron tomography in materials science has flourished with the demand to characterize nanoscale materials in three dimensions (3D). Access to experimental data is vital for developing and validating reconstruction methods that improve resolution and reduce radiation dose requirements. This work presents five high-quality scanning transmission electron microscope (STEM) tomography datasets in order to address the critical need for open access data in this field. The datasets represent the current limits of experimental technique, are of high quality, and contain materials with structural complexity. Included are tomographic series of a hyperbranched Co2P nanocrystal, platinum nanoparticles on a carbon nanofibre imaged over the complete 180° tilt range, a platinum nanoparticle and a tungsten needle both imaged at atomic resolution by equal slope tomography, and a through-focal tilt series of PtCu nanoparticles. A volumetric reconstruction from every dataset is provided for comparison and development of post-processing and visualization techniques. Researchers interested in creating novel data processing and reconstruction algorithms will now have access to state of the art experimental test data.

  12. Materials characterisation by angle-resolved scanning transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Müller-Caspary, Knut; Oppermann, Oliver; Grieb, Tim; Krause, Florian F.; Rosenauer, Andreas; Schowalter, Marco; Mehrtens, Thorsten; Beyer, Andreas; Volz, Kerstin; Potapov, Pavel

    2016-11-01

    Solid-state properties such as strain or chemical composition often leave characteristic fingerprints in the angular dependence of electron scattering. Scanning transmission electron microscopy (STEM) is dedicated to probe scattered intensity with atomic resolution, but it drastically lacks angular resolution. Here we report both a setup to exploit the explicit angular dependence of scattered intensity and applications of angle-resolved STEM to semiconductor nanostructures. Our method is applied to measure nitrogen content and specimen thickness in a GaNxAs1‑x layer independently at atomic resolution by evaluating two dedicated angular intervals. We demonstrate contrast formation due to strain and composition in a Si- based metal-oxide semiconductor field effect transistor (MOSFET) with GexSi1‑x stressors as a function of the angles used for imaging. To shed light on the validity of current theoretical approaches this data is compared with theory, namely the Rutherford approach and contemporary multislice simulations. Inconsistency is found for the Rutherford model in the whole angular range of 16–255 mrad. Contrary, the multislice simulations are applicable for angles larger than 35 mrad whereas a significant mismatch is observed at lower angles. This limitation of established simulations is discussed particularly on the basis of inelastic scattering.

  13. Volume scanning electron microscopy for imaging biological ultrastructure.

    PubMed

    Titze, Benjamin; Genoud, Christel

    2016-11-01

    Electron microscopy (EM) has been a key imaging method to investigate biological ultrastructure for over six decades. In recent years, novel volume EM techniques have significantly advanced nanometre-scale imaging of cells and tissues in three dimensions. Previously, this had depended on the slow and error-prone manual tasks of cutting and handling large numbers of sections, and imaging them one-by-one with transmission EM. Now, automated volume imaging methods mostly based on scanning EM (SEM) allow faster and more reliable acquisition of serial images through tissue volumes and achieve higher z-resolution. Various software tools have been developed to manipulate the acquired image stacks and facilitate quantitative analysis. Here, we introduce three volume SEM methods: serial block-face electron microscopy (SBEM), focused ion beam SEM (FIB-SEM) and automated tape-collecting ultramicrotome SEM (ATUM-SEM). We discuss and compare their capabilities, provide an overview of the full volume SEM workflow for obtaining 3D datasets and showcase different applications for biological research.

  14. Nanomaterial datasets to advance tomography in scanning transmission electron microscopy

    PubMed Central

    Levin, Barnaby D.A.; Padgett, Elliot; Chen, Chien-Chun; Scott, M.C.; Xu, Rui; Theis, Wolfgang; Jiang, Yi; Yang, Yongsoo; Ophus, Colin; Zhang, Haitao; Ha, Don-Hyung; Wang, Deli; Yu, Yingchao; Abruña, Hector D.; Robinson, Richard D.; Ercius, Peter; Kourkoutis, Lena F.; Miao, Jianwei; Muller, David A.; Hovden, Robert

    2016-01-01

    Electron tomography in materials science has flourished with the demand to characterize nanoscale materials in three dimensions (3D). Access to experimental data is vital for developing and validating reconstruction methods that improve resolution and reduce radiation dose requirements. This work presents five high-quality scanning transmission electron microscope (STEM) tomography datasets in order to address the critical need for open access data in this field. The datasets represent the current limits of experimental technique, are of high quality, and contain materials with structural complexity. Included are tomographic series of a hyperbranched Co2P nanocrystal, platinum nanoparticles on a carbon nanofibre imaged over the complete 180° tilt range, a platinum nanoparticle and a tungsten needle both imaged at atomic resolution by equal slope tomography, and a through-focal tilt series of PtCu nanoparticles. A volumetric reconstruction from every dataset is provided for comparison and development of post-processing and visualization techniques. Researchers interested in creating novel data processing and reconstruction algorithms will now have access to state of the art experimental test data. PMID:27272459

  15. Materials characterisation by angle-resolved scanning transmission electron microscopy

    PubMed Central

    Müller-Caspary, Knut; Oppermann, Oliver; Grieb, Tim; Krause, Florian F.; Rosenauer, Andreas; Schowalter, Marco; Mehrtens, Thorsten; Beyer, Andreas; Volz, Kerstin; Potapov, Pavel

    2016-01-01

    Solid-state properties such as strain or chemical composition often leave characteristic fingerprints in the angular dependence of electron scattering. Scanning transmission electron microscopy (STEM) is dedicated to probe scattered intensity with atomic resolution, but it drastically lacks angular resolution. Here we report both a setup to exploit the explicit angular dependence of scattered intensity and applications of angle-resolved STEM to semiconductor nanostructures. Our method is applied to measure nitrogen content and specimen thickness in a GaNxAs1−x layer independently at atomic resolution by evaluating two dedicated angular intervals. We demonstrate contrast formation due to strain and composition in a Si- based metal-oxide semiconductor field effect transistor (MOSFET) with GexSi1−x stressors as a function of the angles used for imaging. To shed light on the validity of current theoretical approaches this data is compared with theory, namely the Rutherford approach and contemporary multislice simulations. Inconsistency is found for the Rutherford model in the whole angular range of 16–255 mrad. Contrary, the multislice simulations are applicable for angles larger than 35 mrad whereas a significant mismatch is observed at lower angles. This limitation of established simulations is discussed particularly on the basis of inelastic scattering. PMID:27849001

  16. Amyloid Structure and Assembly: Insights from Scanning Transmission Electron Microscopy

    SciTech Connect

    Goldsbury, C.; Wall, J.; Baxa, U.; Simon, M. N.; Steven, A. C.; Engel, A.; Aebi, U.; Muller, S. A.

    2011-01-01

    Amyloid fibrils are filamentous protein aggregates implicated in several common diseases such as Alzheimer's disease and type II diabetes. Similar structures are also the molecular principle of the infectious spongiform encephalopathies such as Creutzfeldt-Jakob disease in humans, scrapie in sheep, and of the so-called yeast prions, inherited non-chromosomal elements found in yeast and fungi. Scanning transmission electron microscopy (STEM) is often used to delineate the assembly mechanism and structural properties of amyloid aggregates. In this review we consider specifically contributions and limitations of STEM for the investigation of amyloid assembly pathways, fibril polymorphisms and structural models of amyloid fibrils. This type of microscopy provides the only method to directly measure the mass-per-length (MPL) of individual filaments. Made on both in vitro assembled and ex vivo samples, STEM mass measurements have illuminated the hierarchical relationships between amyloid fibrils and revealed that polymorphic fibrils and various globular oligomers can assemble simultaneously from a single polypeptide. The MPLs also impose strong constraints on possible packing schemes, assisting in molecular model building when combined with high-resolution methods like solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR).

  17. Combined scanning transmission electron microscopy tilt- and focal series.

    PubMed

    Dahmen, Tim; Baudoin, Jean-Pierre; Lupini, Andrew R; Kübel, Christian; Slusallek, Philipp; de Jonge, Niels

    2014-04-01

    In this study, a combined tilt- and focal series is proposed as a new recording scheme for high-angle annular dark-field scanning transmission electron microscopy (STEM) tomography. Three-dimensional (3D) data were acquired by mechanically tilting the specimen, and recording a through-focal series at each tilt direction. The sample was a whole-mount macrophage cell with embedded gold nanoparticles. The tilt-focal algebraic reconstruction technique (TF-ART) is introduced as a new algorithm to reconstruct tomograms from such combined tilt- and focal series. The feasibility of TF-ART was demonstrated by 3D reconstruction of the experimental 3D data. The results were compared with a conventional STEM tilt series of a similar sample. The combined tilt- and focal series led to smaller "missing wedge" artifacts, and a higher axial resolution than obtained for the STEM tilt series, thus improving on one of the main issues of tilt series-based electron tomography.

  18. Amyloid structure and assembly: insights from scanning transmission electron microscopy.

    PubMed

    Goldsbury, Claire; Baxa, Ulrich; Simon, Martha N; Steven, Alasdair C; Engel, Andreas; Wall, Joseph S; Aebi, Ueli; Müller, Shirley A

    2011-01-01

    Amyloid fibrils are filamentous protein aggregates implicated in several common diseases such as Alzheimer's disease and type II diabetes. Similar structures are also the molecular principle of the infectious spongiform encephalopathies such as Creutzfeldt-Jakob disease in humans, scrapie in sheep, and of the so-called yeast prions, inherited non-chromosomal elements found in yeast and fungi. Scanning transmission electron microscopy (STEM) is often used to delineate the assembly mechanism and structural properties of amyloid aggregates. In this review we consider specifically contributions and limitations of STEM for the investigation of amyloid assembly pathways, fibril polymorphisms and structural models of amyloid fibrils. This type of microscopy provides the only method to directly measure the mass-per-length (MPL) of individual filaments. Made on both in vitro assembled and ex vivo samples, STEM mass measurements have illuminated the hierarchical relationships between amyloid fibrils and revealed that polymorphic fibrils and various globular oligomers can assemble simultaneously from a single polypeptide. The MPLs also impose strong constraints on possible packing schemes, assisting in molecular model building when combined with high-resolution methods like solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR).

  19. Nanomaterial datasets to advance tomography in scanning transmission electron microscopy.

    PubMed

    Levin, Barnaby D A; Padgett, Elliot; Chen, Chien-Chun; Scott, M C; Xu, Rui; Theis, Wolfgang; Jiang, Yi; Yang, Yongsoo; Ophus, Colin; Zhang, Haitao; Ha, Don-Hyung; Wang, Deli; Yu, Yingchao; Abruña, Hector D; Robinson, Richard D; Ercius, Peter; Kourkoutis, Lena F; Miao, Jianwei; Muller, David A; Hovden, Robert

    2016-06-07

    Electron tomography in materials science has flourished with the demand to characterize nanoscale materials in three dimensions (3D). Access to experimental data is vital for developing and validating reconstruction methods that improve resolution and reduce radiation dose requirements. This work presents five high-quality scanning transmission electron microscope (STEM) tomography datasets in order to address the critical need for open access data in this field. The datasets represent the current limits of experimental technique, are of high quality, and contain materials with structural complexity. Included are tomographic series of a hyperbranched Co2P nanocrystal, platinum nanoparticles on a carbon nanofibre imaged over the complete 180° tilt range, a platinum nanoparticle and a tungsten needle both imaged at atomic resolution by equal slope tomography, and a through-focal tilt series of PtCu nanoparticles. A volumetric reconstruction from every dataset is provided for comparison and development of post-processing and visualization techniques. Researchers interested in creating novel data processing and reconstruction algorithms will now have access to state of the art experimental test data.

  20. Materials characterisation by angle-resolved scanning transmission electron microscopy.

    PubMed

    Müller-Caspary, Knut; Oppermann, Oliver; Grieb, Tim; Krause, Florian F; Rosenauer, Andreas; Schowalter, Marco; Mehrtens, Thorsten; Beyer, Andreas; Volz, Kerstin; Potapov, Pavel

    2016-11-16

    Solid-state properties such as strain or chemical composition often leave characteristic fingerprints in the angular dependence of electron scattering. Scanning transmission electron microscopy (STEM) is dedicated to probe scattered intensity with atomic resolution, but it drastically lacks angular resolution. Here we report both a setup to exploit the explicit angular dependence of scattered intensity and applications of angle-resolved STEM to semiconductor nanostructures. Our method is applied to measure nitrogen content and specimen thickness in a GaNxAs1-x layer independently at atomic resolution by evaluating two dedicated angular intervals. We demonstrate contrast formation due to strain and composition in a Si- based metal-oxide semiconductor field effect transistor (MOSFET) with GexSi1-x stressors as a function of the angles used for imaging. To shed light on the validity of current theoretical approaches this data is compared with theory, namely the Rutherford approach and contemporary multislice simulations. Inconsistency is found for the Rutherford model in the whole angular range of 16-255 mrad. Contrary, the multislice simulations are applicable for angles larger than 35 mrad whereas a significant mismatch is observed at lower angles. This limitation of established simulations is discussed particularly on the basis of inelastic scattering.

  1. Endolithic algae and micrite envelope formation in Bahamian oolites as revealed by scanning electron microscopy.

    NASA Technical Reports Server (NTRS)

    Margolis, S.; Rex, R. W.

    1971-01-01

    Examination of Holocene Bahamian ooelites by scanning electron and light microscopy has revealed the morphology and orientation of aragonite crystals in the lamellar ooelitic envelope, and their modification by the boring activities of endolithic algae. The voids produced by these algae are found in progressive stages of being lined and filled with precipitated microcrystalline aragonite, which is similar to the process of micrite envelope formation in molluscan and other skeletal carbonate grains.

  2. Scanning transmission electron microscopy strain measurement from millisecond frames of a direct electron charge coupled device

    SciTech Connect

    Mueller, Knut; Rosenauer, Andreas; Ryll, Henning; Ordavo, Ivan; Ihle, Sebastian; Soltau, Heike; Strueder, Lothar; Volz, Kerstin; Zweck, Josef

    2012-11-19

    A high-speed direct electron detection system is introduced to the field of transmission electron microscopy and applied to strain measurements in semiconductor nanostructures. In particular, a focused electron probe with a diameter of 0.5 nm was scanned over a fourfold quantum layer stack with alternating compressive and tensile strain and diffracted discs have been recorded on a scintillator-free direct electron detector with a frame time of 1 ms. We show that the applied algorithms can accurately detect Bragg beam positions despite a significant point spread each 300 kV electron causes during detection on the scintillator-free camera. For millisecond exposures, we find that strain can be measured with a precision of 1.3 Multiplication-Sign 10{sup -3}, enabling, e.g., strain mapping in a 100 Multiplication-Sign 100 nm{sup 2} region with 0.5 nm resolution in 40 s.

  3. A differentially pumped secondary electron detector for low-vacuum scanning electron microscopy.

    PubMed

    Jacka, M; Zadrazil, M; Lopour, F

    2003-01-01

    A new design of secondary electron (SE) detector is described for use in low-vacuum scanning electron microscopes. Its distinguishing feature is a separate detector chamber, which can be maintained at a pressure independent of the pressure in the specimen chamber. The two chambers are separated by a perforated membrane or mesh across which an electric field is applied, making it relatively transparent to low-energy electrons but considerably less so to the gas molecules. The benefits of this arrangement are discussed. The final means of detecting the electrons can be a conventional scintillator and photomultiplier arrangement or any of the methods using the ambient gas as an amplifying medium. Images obtained with the detector show good SE contrast and low backscattered electron contribution.

  4. Probing Individual Ice Nucleation Events with Environmental Scanning Electron Microscopy

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  5. The current state of electronic consultation and electronic referral systems in Canada: an environmental scan.

    PubMed

    Liddy, Clare; Hogel, Matthew; Blazkho, Valerie; Keely, Erin

    2015-01-01

    Access to specialist care is a point of concern for patients, primary care providers, and specialists in Canada. Innovative e-health platforms such as electronic consultation (eConsultation) and referral (eReferral) can improve access to specialist care. These systems allow physicians to communicate asynchronously and could reduce the number of unnecessary referrals that clog wait lists, provide a record of the patient's journey through the referral system, and lead to more efficient visits. Little is known about the current state of eConsultation and eReferral in Canada. The purpose of this work was to identify current systems and gain insight into the design and implementation process of existing systems. An environmental scan approach was used, consisting of a systematic and grey literature review, and targeted semi-structured key informant interviews. Only three eConsultation/eReferral systems are currently in operation in Canada. Four themes emerged from the interviews: eReferral is an end goal for those provinces without an active eReferral system, re-organization of the referral process is a necessity prior to automation, engaging the end-user is essential, and technological incompatibilities are major impediments to progress. Despite the acknowledged need to improve the referral system and increase government spending on health information technology, eConsultation and eReferral systems remain scarce as Canada lags behind the rest of the developed world.

  6. Visualizing bone porosities using a tabletop scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, D.; DaPonte, J.; Broadbridge, C. C.; Daniel, D.; Alter, L.

    2010-04-01

    Pores are naturally occurring entities in bone. Changes in pore size and number are often associated with diseases such as Osteoporosis and even microgravity during spaceflight. Studying bone perforations may yield great insight into bone's material properties, including bone density and may contribute to identifying therapies to halt or potentially reverse bone loss. Current technologies used in this field include nuclear magnetic resonance, micro-computed tomography and the field emission scanning electron microscope (FE-SEM) 2, 5. However, limitations in each method limit further advancement. The objective of this study was to assess the effectiveness of using a new generation of analytical instruments, the TM-1000 tabletop, SEM with back-scatter electron (BSE) detector, to analyze cortical bone porosities. Hind limb unloaded and age-based controlled mouse femurs were extracted and tested in vitro for changes in pores on the periosteal surface. An important advantage of using the tabletop is the simplified sample preparation that excludes extra coatings, dehydration and fixation steps that are otherwise required for conventional SEM. For quantitative data, pores were treated as particles in order to use an analyze particles feature in the NIH ImageJ software. Several image-processing techniques for background smoothing, thresholding and filtering were employed to produce a binary image suitable for particle analysis. It was hypothesized that the unloaded bones would show an increase in pore area, as the lack of mechanical loading would affect bone-remodeling processes taking place in and around pores. Preliminary results suggest only a slight different in frequency but not in size of pores between unloaded and control femurs.

  7. Automated Quantitative Rare Earth Elements Mineralogy by Scanning Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Sindern, Sven; Meyer, F. Michael

    2016-09-01

    Increasing industrial demand of rare earth elements (REEs) stems from the central role they play for advanced technologies and the accelerating move away from carbon-based fuels. However, REE production is often hampered by the chemical, mineralogical as well as textural complexity of the ores with a need for better understanding of their salient properties. This is not only essential for in-depth genetic interpretations but also for a robust assessment of ore quality and economic viability. The design of energy and cost-efficient processing of REE ores depends heavily on information about REE element deportment that can be made available employing automated quantitative process mineralogy. Quantitative mineralogy assigns numeric values to compositional and textural properties of mineral matter. Scanning electron microscopy (SEM) combined with a suitable software package for acquisition of backscatter electron and X-ray signals, phase assignment and image analysis is one of the most efficient tools for quantitative mineralogy. The four different SEM-based automated quantitative mineralogy systems, i.e. FEI QEMSCAN and MLA, Tescan TIMA and Zeiss Mineralogic Mining, which are commercially available, are briefly characterized. Using examples of quantitative REE mineralogy, this chapter illustrates capabilities and limitations of automated SEM-based systems. Chemical variability of REE minerals and analytical uncertainty can reduce performance of phase assignment. This is shown for the REE phases parisite and synchysite. In another example from a monazite REE deposit, the quantitative mineralogical parameters surface roughness and mineral association derived from image analysis are applied for automated discrimination of apatite formed in a breakdown reaction of monazite and apatite formed by metamorphism prior to monazite breakdown. SEM-based automated mineralogy fulfils all requirements for characterization of complex unconventional REE ores that will become

  8. Scanning transmission electron microscopy methods for the analysis of nanoparticles.

    PubMed

    Ponce, Arturo; Mejía-Rosales, Sergio; José-Yacamán, Miguel

    2012-01-01

    Here we review the scanning transmission electron microscopy (STEM) characterization technique and STEM imaging methods. We describe applications of STEM for studying inorganic nanoparticles, and other uses of STEM in biological and health sciences and discuss how to interpret STEM results. The STEM imaging mode has certain benefits compared with the broad-beam illumination mode; the main advantage is the collection of the information about the specimen using a high angular annular dark field (HAADF) detector, in which the images registered have different levels of contrast related to the chemical composition of the sample. Another advantage of its use in the analysis of biological samples is its contrast for thick stained sections, since HAADF images of samples with thickness of 100-120 nm have notoriously better contrast than those obtained by other techniques. Combining the HAADF-STEM imaging with the new aberration correction era, the STEM technique reaches a direct way to imaging the atomistic structure and composition of nanostructures at a sub-angstrom resolution. Thus, alloying in metallic nanoparticles is directly resolved at atomic scale by the HAADF-STEM imaging, and the comparison of the STEM images with results from simulations gives a very powerful way of analysis of structure and composition. The use of X-ray energy dispersive spectroscopy attached to the electron microscope for STEM mode is also described. In issues where characterization at the atomic scale of the interaction between metallic nanoparticles and biological systems is needed, all the associated techniques to STEM become powerful tools for the best understanding on how to use these particles in biomedical applications.

  9. Scanning electron microscopic analyses of Ferrocyanide tank wastes for the Ferrocyanide safety program

    SciTech Connect

    Callaway, W.S.

    1995-09-01

    This is Fiscal Year 1995 Annual Report on the progress of activities relating to the application of scanning electron microscopy in addressing the Ferrocyanide Safety Issue associated with Hanford Site high-level radioactive waste tanks. The status of the FY 1995 activities directed towards establishing facilities capable of providing SEM based micro-characterization of ferrocyanide tank wastes is described. A summary of key events in the SEM task over FY 1995 and target activities in FY 1996 are presented. A brief overview of the potential applications of computer controlled SEM analytical data in light of analyses of ferrocyanide simulants performed by an independent contractor is also presented

  10. Semiautomatic classification of cementitious materials using scanning electron microscope images

    NASA Astrophysics Data System (ADS)

    Drumetz, Lucas; Mura, Mauro Dalla; Meulenyzer, Samuel; Lombard, Sébastien; Chanussot, Jocelyn

    2015-11-01

    Segmentation and classification are prolific research topics in the image processing community. These topics have been increasingly used in the context of analysis of cementitious materials on images acquired with a scanning electron microscope. Indeed, there is a need to be able to detect and to quantify the materials present in a cement paste in order to follow the chemical reactions occurring in the material even days after the solidification. We propose a new approach for segmentation and classification of cementitious materials based on the denoising of the data with a block-matching three-dimensional (3-D) algorithm, binary partition tree (BPT) segmentation, support vector machines (SVM) classification, and interactivity with the user. The BPT provides a hierarchical representation of the spatial regions of the data, allowing a segmentation to be selected among the admissible partitions of the image. SVMs are used to obtain a classification map of the image. This approach combines state-of-the-art image processing tools with user interactivity to allow a better segmentation to be performed, or to help the classifier discriminate the classes better. We show that the proposed approach outperforms a previous method when applied to synthetic data and several real datasets coming from cement samples, both qualitatively with visual examination and quantitatively with the comparison of experimental results with theoretical ones.

  11. Histological preparation of developing vestibular otoconia for scanning electron microscopy

    NASA Technical Reports Server (NTRS)

    Huss, D.; Dickman, J. D.

    2003-01-01

    The unique nature of vestibular otoconia as calcium carbonate biominerals makes them particularly susceptible to chemical deformation during histological processing. We fixed and stored otoconia from all three otolith endorgans of embryonic, hatchling and adult Japanese quail in glutaraldehyde containing either phosphate or non-phosphate buffers for varying lengths of time and processed them for scanning electron microscopy. Otoconia from all age groups and otolith endorgans processed in 0.1 M phosphate buffer (pH 7.4) showed abnormal surface morphology when compared to acetone fixed controls. Otoconia processed in 0.1 M sodium cacodylate or HEPES buffered artificial endolymph (pH 7.4) showed normal morphology that was similar to controls. The degree of otoconial deformation was directly related to the time exposed to phosphate buffer. Short duration exposure produced particulate deformations while longer exposures resulted in fused otoconia that formed solid sheets. Otoconial surface deformation and fusing was independent of the glutaraldehyde component of the histological processing. These findings should help vestibular researchers to develop appropriate histological processing protocols in future studies of otoconia.

  12. Scanning electron microscopy and roughness study of dental composite degradation.

    PubMed

    Soares, Luís Eduardo Silva; Cortez, Louise Ribeiro; Zarur, Raquel de Oliveira; Martin, Airton Abrahão

    2012-04-01

    Our aim was to test the hypothesis that the use of mouthwashes, consumption of soft drinks, as well as the type of light curing unit (LCU), would change the surface roughness (Ra) and morphology of a nanofilled composite resin (Z350® 3M ESPE). Samples (80) were divided into eight groups: Halogen LCU, group 1, saliva (control); group 2, Pepsi Twist®; group 3, Listerine®; group 4, Colgate Plax®; LED LCU, group 5, saliva; group 6, Pepsi Twist®; group 7, Listerine®; group 8, Colgate Plax®. Ra values were measured at baseline, and after 7 and 14 days. One specimen of each group was prepared for scanning electron microscopy analysis after 14 days. The data were subjected to multifactor analysis of variance at a 95% confidence followed by Tukey's honestly significant difference post-hoc test. All the treatments resulted in morphological changes in composite resin surface, and the most significant change was in Pepsi Twist® groups. The samples of G6 had the greatest increase in Ra. The immersion of nanofilled resin in mouthwashes with alcohol and soft drink increases the surface roughness. Polymerization by halogen LCU (reduced light intensity) associated with alcohol contained mouthwash resulted in significant roughness on the composite.

  13. In situ fatigue loading stage inside scanning electron microscope

    NASA Technical Reports Server (NTRS)

    Telesman, Jack; Kantzos, Peter; Brewer, David

    1988-01-01

    A fatigue loading stage inside a scanning electron microscopy (SEM) was developed. The stage allows dynamic and static high-magnification and high-resolution viewing of the fatigue crack initiation and crack propagation processes. The loading stage is controlled by a closed-loop servohydraulic system. Maximum load is 1000 lb (4450 N) with test frequencies ranging up to 30 Hz. The stage accommodates specimens up to 2 inches (50 mm) in length and tolerates substantial specimen translation to view the propagating crack. At room temperature, acceptable working resolution is obtainable for magnifications ranging up to 10,000X. The system is equipped with a high-temperature setup designed for temperatures up to 2000 F (1100 C). The signal can be videotaped for further analysis of the pertinent fatigue damage mechanisms. The design allows for quick and easy interchange and conversion of the SEM from a loading stage configuration to its normal operational configuration and vice versa. Tests are performed entirely in the in-situ mode. In contrast to other designs, the NASA design has greatly extended the life of the loading stage by not exposing the bellows to cyclic loading. The loading stage was used to investigate the fatigue crack growth mechanisms in the (100)-oriented PWA 1480 single-crystal, nickel-based supperalloy. The high-magnification observations revealed the details of the crack growth processes.

  14. Scanning electron microscopic and profilometric study of different sharpening stones.

    PubMed

    Andrade Acevedo, Roberto Antonio; Cardozo, Ana Karina Veloso; Sampaio, José Eduardo César

    2006-01-01

    Scaling and root planing contribute to the recovery of periodontal health. All periodontal instruments loose their fine cutting angle after use. To maintain this angle, correct sharpening is required using specifically designed stones. The characteristics of sharpening stones can be compared to the blade of the instruments and also transported to root surface during instrumentation. Root smoothness is related to the quality of the blade. Therefore, the purpose of this study was to evaluate the characteristics of 9 sharpening stones by scanning electron microscopic and profilometric analyses. Ceramic and Neumar stones were very fine and both may be recommended to maintain the sharpness of the instruments. Arkansas, Thompson and CE stones presented greater roughness with very regular and round particles, and are suitable for maintenance of the cutting angle. In addition, these stones may be indicated for the routine sharpening of the instruments that are partly dull. Oxide Aluminum, Carborundum and JON stones were the coarsest with large irregular particles and may be indicated for initial sharpening of totally dull instruments with completion of sharpening with finer stones.

  15. Environmental scanning electron microscope imaging examples related to particle analysis.

    PubMed

    Wight, S A; Zeissler, C J

    1993-08-01

    This work provides examples of some of the imaging capabilities of environmental scanning electron microscopy applied to easily charged samples relevant to particle analysis. Environmental SEM (also referred to as high pressure or low vacuum SEM) can address uncoated samples that are known to be difficult to image. Most of these specimens are difficult to image by conventional SEM even when coated with a conductive layer. Another area where environmental SEM is particularly applicable is for specimens not compatible with high vacuum, such as volatile specimens. Samples from which images were obtained that otherwise may not have been possible by conventional methods included fly ash particles on an oiled plastic membrane impactor substrate, a one micrometer diameter fiber mounted on the end of a wire, uranium oxide particles embedded in oil-bearing cellulose nitrate, teflon and polycarbonate filter materials with collected air particulate matter, polystyrene latex spheres on cellulosic filter paper, polystyrene latex spheres "loosely" sitting on a glass slide, and subsurface tracks in an etched nuclear track-etch detector. Surface charging problems experienced in high vacuum SEMs are virtually eliminated in the low vacuum SEM, extending imaging capabilities to samples previously difficult to use or incompatible with conventional methods.

  16. Surface treatment of feldspathic porcelain: scanning electron microscopy analysis

    PubMed Central

    Valian, Azam

    2014-01-01

    PURPOSE Topographic analysis of treated ceramics provides qualitative information regarding the surface texture affecting the micromechanical retention and locking of resin-ceramics. This study aims to compare the surface microstructure following different surface treatments of feldspathic porcelain. MATERIALS AND METHODS This in-vitro study was conducted on 72 porcelain discs randomly divided into 12 groups (n=6). In 9 groups, feldspathic surfaces were subjected to sandblasting at 2, 3 or 4 bar pressure for 5, 10 or 15 seconds with 50 µm alumina particles at a 5 mm distance. In group 10, 9.5% hydrofluoric acid (HF) gel was applied for 120 seconds. In group 11, specimens were sandblasted at 3 bar pressure for 10 seconds and then conditioned with HF. In group 12, specimens were first treated with HF and then sandblasted at 3 bar pressure for 10 seconds. All specimens were then evaluated under scanning electron microscopy (SEM) at different magnifications. RESULTS SEM images of HF treated specimens revealed deep porosities of variable sizes; whereas, the sandblasted surfaces were more homogenous and had sharper peaks. Increasing the pressure and duration of sandblasting increased the surface roughness. SEM images of the two combined techniques showed that in group 11 (sandblasted first), HF caused deeper porosities; whereas in group 12 (treated with HF first) sandblasting caused irregularities with less homogeneity. CONCLUSION All surface treatments increased the surface area and caused porous surfaces. In groups subjected to HF, the porosities were deeper than those in sandblasted only groups. PMID:25352961

  17. Characterization of paired helical filaments by scanning transmission electron microscopy.

    PubMed

    Ksiezak-Reding, Hanna; Wall, Joseph S

    2005-07-01

    Paired helical filaments (PHFs) are abnormal twisted filaments composed of hyperphosphorylated tau protein. They are found in Alzheimer's disease and other neurodegenerative disorders designated as tauopathies. They are a major component of intracellular inclusions known as neurofibrillary tangles (NFTs). The objective of this review is to summarize various structural studies of PHFs in which using scanning transmission electron microscopy (STEM) has been particularly informative. STEM provides shape and mass per unit length measurements important for studying ultrastructural aspects of filaments. These include quantitative comparisons between dispersed and aggregated populations of PHFs as well as comparative studies of PHFs in Alzheimer's disease and other neurodegenerative disorders. Other approaches are also discussed if relevant or complementary to studies using STEM, e.g., application of a novel staining reagent, Nanovan. Our understanding of the PHF structure and the development of PHFs into NFTs is presented from a historical perspective. Others goals are to describe the biochemical and ultrastructural complexity of authentic PHFs, to assess similarities between authentic and synthetic PHFs, and to discuss recent advances in PHF modeling.

  18. Non-thermal plasma mills bacteria: Scanning electron microscopy observations

    SciTech Connect

    Lunov, O. Churpita, O.; Zablotskii, V.; Jäger, A.; Dejneka, A.; Deyneka, I. G.; Meshkovskii, I. K.; Syková, E.; Kubinová, Š.

    2015-02-02

    Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanning electron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin–stained rat skin sections from plasma–treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy.

  19. Scanning Electron Microscopy of Colonies of Six Species of Candida

    PubMed Central

    Joshi, K. R.; Wheeler, E. E.; Gavin, J. B.

    1973-01-01

    Thirty strains of six species of Candida isolated from patients were cultured for 60 h on Sabouraud agar, freeze-dried, and examined with a scanning electron microscope. The colonies were circular (Candida albicans, C. guilliermondii) or oval (C. tropicalis, C. pseudotropicalis, C. krusei, C. parakrusei) in outline, and those of C. pseudotropicalis and C. krusei had an irregular outline due to a peripheral pseudomycelium. The morphology of individual microorganisms was examined at the margins and apex of those species which lacked a surface coat (C. pseudotropicalis, C. krusei, C. parakrusei, C. guilliermondii), and through cracks in the surface coating of those which showed a surface coat (C. albicans, C. tropicalis). All species showed buds, bud scars, and interconnecting intercellular processes, but were generally spherical (C. albicans, C. tropicalis) or ovoid (C. pseudotropicalis, C. krusei, C. parakrusei, C. guilliermondii) in fixed preparations. In unfixed material, individual organisms were almost invariably indented. Fixation with 3% glutaraldehyde and washing before freeze-drying caused partial removal of the surface coating of colonies of C. albicans and C. tropicalis, which persisted only as irregular sheets or as a filamentous meshwork. This filamentous meshwork was also present among the organisms of colonies of C. albicans, C. tropicalis, and C. pseudotropicalis. It is concluded that these filaments represent the precipitation or unmasking of some component of the intercellular matrix of these organisms. Images PMID:4197906

  20. Non-destructive imaging of buried electronic interfaces using a decelerated scanning electron beam.

    PubMed

    Hirohata, Atsufumi; Yamamoto, Yasuaki; Murphy, Benedict A; Vick, Andrew J

    2016-09-02

    Recent progress in nanotechnology enables the production of atomically abrupt interfaces in multilayered junctions, allowing for an increase in the number of transistors in a processor. However, uniform electron transport has not yet been achieved across the entire interfacial area in junctions due to the existence of local defects, causing local heating and reduction in transport efficiency. To date, junction uniformity has been predominantly assessed by cross-sectional transmission electron microscopy, which requires slicing and milling processes that can potentially introduce additional damage and deformation. It is therefore essential to develop an alternative non-destructive method. Here we show a non-destructive technique using scanning electron microscopy to map buried junction properties. By controlling the electron-beam energy, we demonstrate the contrast imaging of local junction resistances at a controlled depth. This technique can be applied to any buried junctions, from conventional semiconductor and metal devices to organic devices.

  1. Non-destructive imaging of buried electronic interfaces using a decelerated scanning electron beam

    NASA Astrophysics Data System (ADS)

    Hirohata, Atsufumi; Yamamoto, Yasuaki; Murphy, Benedict A.; Vick, Andrew J.

    2016-09-01

    Recent progress in nanotechnology enables the production of atomically abrupt interfaces in multilayered junctions, allowing for an increase in the number of transistors in a processor. However, uniform electron transport has not yet been achieved across the entire interfacial area in junctions due to the existence of local defects, causing local heating and reduction in transport efficiency. To date, junction uniformity has been predominantly assessed by cross-sectional transmission electron microscopy, which requires slicing and milling processes that can potentially introduce additional damage and deformation. It is therefore essential to develop an alternative non-destructive method. Here we show a non-destructive technique using scanning electron microscopy to map buried junction properties. By controlling the electron-beam energy, we demonstrate the contrast imaging of local junction resistances at a controlled depth. This technique can be applied to any buried junctions, from conventional semiconductor and metal devices to organic devices.

  2. Non-destructive imaging of buried electronic interfaces using a decelerated scanning electron beam

    PubMed Central

    Hirohata, Atsufumi; Yamamoto, Yasuaki; Murphy, Benedict A.; Vick, Andrew J.

    2016-01-01

    Recent progress in nanotechnology enables the production of atomically abrupt interfaces in multilayered junctions, allowing for an increase in the number of transistors in a processor. However, uniform electron transport has not yet been achieved across the entire interfacial area in junctions due to the existence of local defects, causing local heating and reduction in transport efficiency. To date, junction uniformity has been predominantly assessed by cross-sectional transmission electron microscopy, which requires slicing and milling processes that can potentially introduce additional damage and deformation. It is therefore essential to develop an alternative non-destructive method. Here we show a non-destructive technique using scanning electron microscopy to map buried junction properties. By controlling the electron-beam energy, we demonstrate the contrast imaging of local junction resistances at a controlled depth. This technique can be applied to any buried junctions, from conventional semiconductor and metal devices to organic devices. PMID:27586090

  3. Electron channeling contrast imaging studies of nonpolar nitrides using a scanning electron microscope

    SciTech Connect

    Naresh-Kumar, G.; Kraeusel, S.; Bruckbauer, J.; Edwards, P. R.; Hourahine, B.; Trager-Cowan, C.; Mauder, C.; Heuken, M.; Wang, K. R.; Trampert, A.; Kalisch, H.; Vescan, A.; Giesen, C.; Day, A. P.

    2013-04-08

    Threading dislocations, stacking faults, and associated partial dislocations significantly degrade the optical and electrical properties of materials such as non-polar III-nitride semiconductor thin films. Stacking faults are generally difficult to detect and quantify with existing characterization techniques. We demonstrate the use of electron channeling contrast imaging in the scanning electron microscope to non-destructively reveal basal plane stacking faults terminated by partial dislocations in m-plane GaN and InGaN/GaN multiple quantum well structures grown on {gamma}-LiAlO{sub 2} by metal organic vapor phase epitaxy.

  4. Ultrahigh-Resolution Scanning Transmission Electron Microscopy with Sub-Angstrom-Sized Electron Beams

    SciTech Connect

    Abe, E.; Pennycook, Stephen J

    2005-01-01

    The scanning transmission electron microscope (STEM) with an annular dark-field (ADF) detector provides atomic-resolution incoherent images, whose resolution is dominated, to a good approximation, by the size of convergent electron beams. Improving a spherical aberration of microscope objective lenses has been successful in converging the beam into sub-angstrom scale, promising a remarkably higher resolution for STEM. Here we describe the performance of aberration-corrected 300kV-STEM-the world-best STEM available today. The results clearly demonstrate that a sub-angstrom resolution has been indeed achieved for not only simple structures but also structurally complex systems (quasicrystals).

  5. Observation of Live Ticks (Haemaphysalis flava) by Scanning Electron Microscopy under High Vacuum Pressure

    PubMed Central

    Ishigaki, Yasuhito; Nakamura, Yuka; Oikawa, Yosaburo; Yano, Yasuhiro; Kuwabata, Susumu; Nakagawa, Hideaki; Tomosugi, Naohisa; Takegami, Tsutomu

    2012-01-01

    Scanning electron microscopes (SEM), which image sample surfaces by scanning with an electron beam, are widely used for steric observations of resting samples in basic and applied biology. Various conventional methods exist for SEM sample preparation. However, conventional SEM is not a good tool to observe living organisms because of the associated exposure to high vacuum pressure and electron beam radiation. Here we attempted SEM observations of live ticks. During 1.5×10−3 Pa vacuum pressure and electron beam irradiation with accelerated voltages (2–5 kV), many ticks remained alive and moved their legs. After 30-min observation, we removed the ticks from the SEM stage; they could walk actively under atmospheric pressure. When we tested 20 ticks (8 female adults and 12 nymphs), they survived for two days after SEM observation. These results indicate the resistance of ticks against SEM observation. Our second survival test showed that the electron beam, not vacuum conditions, results in tick death. Moreover, we describe the reaction of their legs to electron beam exposure. These findings open the new possibility of SEM observation of living organisms and showed the resistance of living ticks to vacuum condition in SEM. These data also indicate, for the first time, the usefulness of tick as a model system for biology under extreme condition. PMID:22431980

  6. SCAN+

    SciTech Connect

    Kenneth Krebs, John Svoboda

    2009-11-01

    SCAN+ is a software application specifically designed to control the positioning of a gamma spectrometer by a two dimensional translation system above spent fuel bundles located in a sealed spent fuel cask. The gamma spectrometer collects gamma spectrum information for the purpose of spent fuel cask fuel loading verification. SCAN+ performs manual and automatic gamma spectrometer positioning functions as-well-as exercising control of the gamma spectrometer data acquisitioning functions. Cask configuration files are used to determine the positions of spent fuel bundles. Cask scanning files are used to determine the desired scan paths for scanning a spent fuel cask allowing for automatic unattended cask scanning that may take several hours.

  7. Epidermal growth factor receptor subunit locations determined in hydrated cells with environmental scanning electron microscopy.

    PubMed

    Peckys, Diana B; Baudoin, Jean-Pierre; Eder, Magdalena; Werner, Ulf; de Jonge, Niels

    2013-01-01

    Imaging single epidermal growth factor receptors (EGFR) in intact cells is presently limited by the available microscopy methods. Environmental scanning electron microscopy (ESEM) of whole cells in hydrated state in combination with specific labeling with gold nanoparticles was used to localize activated EGFRs in the plasma membranes of COS7 and A549 cells. The use of a scanning transmission electron microscopy (STEM) detector yielded a spatial resolution of 3 nm, sufficient to identify the locations of individual EGFR dimer subunits. The sizes and distribution of dimers and higher order clusters of EGFRs were determined. The distance between labels bound to dimers amounted to 19 nm, consistent with a molecular model. A fraction of the EGFRs was found in higher order clusters with sizes ranging from 32-56 nm. ESEM can be used for quantitative whole cell screening studies of membrane receptors, and for the study of nanoparticle-cell interactions in general.

  8. Picometre-precision analysis of scanning transmission electron microscopy images of platinum nanocatalysts.

    PubMed

    Yankovich, Andrew B; Berkels, Benjamin; Dahmen, W; Binev, P; Sanchez, S I; Bradley, S A; Li, Ao; Szlufarska, Izabela; Voyles, Paul M

    2014-06-11

    Measuring picometre-scale shifts in the positions of individual atoms in materials provides new insight into the structure of surfaces, defects and interfaces that influence a broad variety of materials' behaviour. Here we demonstrate sub-picometre precision measurements of atom positions in aberration-corrected Z-contrast scanning transmission electron microscopy images based on the non-rigid registration and averaging of an image series. Non-rigid registration achieves five to seven times better precision than previous methods. Non-rigidly registered images of a silica-supported platinum nanocatalyst show pm-scale contraction of atoms at a (111)/(111) corner towards the particle centre and expansion of a flat (111) facet. Sub-picometre precision and standardless atom counting with <1 atom uncertainty in the same scanning transmission electron microscopy image provide new insight into the three-dimensional atomic structure of catalyst nanoparticle surfaces, which contain the active sites controlling catalytic reactions.

  9. Treatment of in-vivo bladder tissue with electronically scanned high-intensity focused ultrasound

    NASA Astrophysics Data System (ADS)

    Feuillu, Benoit; Lacoste, Francois; Schlosser, Jacques; Vallancien, Guy

    1998-04-01

    Introduction: The efficacy of extracorporeal High Intensity Focused Ultrasound (HIFU) on bladder wall has been demonstrated. However, the treatment is still slow, needing about 15 min to treat 1 cm2. Objectives: Demonstrate the feasibility of HIFU with electronic scanning and reduce the during of HIFU treatments. Conclusions: Necrotic lesions on bladder posterior wall can be obtained with HIFU treatments using electronic scanning of the focal point. Average treatment duration with electronic scanning is reduced to 3 min 30 sec/cm2.

  10. 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.

  11. From the physics of secondary electron emission to image contrasts in scanning electron microscopy.

    PubMed

    Cazaux, Jacques

    2012-01-01

    Image formation in scanning electron microscopy (SEM) is a combination of physical processes, electron emissions from the sample, and of a technical process related to the detection of a fraction of these electrons. For the present survey of image contrasts in SEM, simplified considerations in the physics of the secondary electron emission yield, δ, are combined with the effects of a partial collection of the emitted secondary electrons. Although some consideration is initially given to the architecture of modern SEM, the main attention is devoted to the material contrasts with the respective roles of the sub-surface and surface compositions of the sample, as well as with the roles of the field effects in the vacuum gap. The recent trends of energy filtering in normal SEM and the reduction of the incident energy to a few electron volts in very low-energy electron microscopy are also considered. For an understanding by the SEM community, the mathematical expressions are explained with simple physical arguments.

  12. Improved specimen coating technique for scanning electron microscope observation of decomposer microorganisms.

    PubMed

    Draggan, S

    1976-02-01

    Sputter coating of leaf litter microbe samples provides scanning electron microscope images with greater information content than either vacuum evaporation of thin metal coatings or tissue conductance.

  13. 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.

  14. Visualization of Microbial Biomarkers by Scanning Electron Microscopy

    NASA Technical Reports Server (NTRS)

    Wainwright, Norman R.; Allen, Carlton C.; Child, Alice

    2001-01-01

    . Fortunately, many antimicrobial defense systems of higher organisms require sensitive detection to combat microbial pathogens. We employ here the primitive immune system of the evolutionarily ancient horseshoe crab, Limulus polyphemus. This species relies on multi-enzyme signal amplification detection of cell wall molecules and they can be applied to the development of useful detectors of life. An extension of this work includes the visualization of microbial signatures by labeling LAL components with chromogenic or electron dense markers. The protein Limulus Anti-LPS Factor (LALF) has an extremely high affinity for LPS. By coupling LALF binding with colloidal gold labels we demonstrate a correlation of the structures visible by electron microscopy with biochemical evidence of microbial cell wall materials. Pure silica particles were mixed with cultures of E. coli (10(exp 6) cfu/mL). Samples were washed sequentially with buffered saline, LALF, antibody to LALF and finally colloidal gold-labeled Protein A. Negative controls were not exposed to E. coli but received identical treatment otherwise. Samples were coated with carbon and imaged on a JEOL JSM-840 scanning electron microscope with LaB6 source in the back scatter mode with the JEOL annular back scatter detector. 20 nm-scale black spots in this contrast-reversed image originate from electrons back-scattered by gold atoms. Negative controls did not give any signal. Future work will expand application of this technique to soil simulants and mineralized rock samples.

  15. Characterization of humic substances by environmental scanning electron microscopy.

    PubMed

    Redwood, Paul S; Lead, Jamie R; Harrison, Roy M; Jones, Ian P; Stoll, Serge

    2005-04-01

    Environmental scanning electron microscopy (ESEM) is a new technique capable of imaging micron and submicron particles. Here, we have applied it to image and quantify natural aquatic organic matter (standard Suwannee River humic acid, SRHA). Uniquely, we have observed the humic aggregate structures as a function of humidity and pH. Large aggregates of tens of micrometers were observed as the dominant material under all conditions, although much smaller material was also observed. Fractal dimensions (D) were calculated between 1.48 and 1.70, although these values were not statistically different under conditions of low humidity. However, D values calculated at high humidities (85%) during the rehydration phase were significantly lower (1.48+/-0.01) than in the initial dehydration phase (1.69+/-0.01). This hysteresis indicated that full rehydration of the HS was either kinetically slow or irreversible after dehydration. Fractal analysis of ESEM images was also performed to probe the change in aggregate structure as a function of pH. Minimum values were calculated at neutral pHs, rising by 0.1-0.2 at both high and low pHs because of a combination of the physical chemistry of HS and the impacts of the drying regime within the ESEM. Thus, ESEM was an important complementary technique to other analytical methods. At present, ESEM cannot be used to image nonperturbed natural samples. However, the method is an ideal method for probing the changes in colloid structure as function of hydration state and has the potential to perform fully quantitative and nonperturbing analysis of colloidal structure.

  16. Optical microscopy versus scanning electron microscopy in urolithiasis.

    PubMed

    Marickar, Y M Fazil; Lekshmi, P R; Varma, Luxmi; Koshy, Peter

    2009-10-01

    Stone analysis is incompletely done in many clinical centers. Identification of the stone component is essential for deciding future prophylaxis. X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy (SEM) still remains a distant dream for routine hospital work. It is in this context that optical microscopy is suggested as an alternate procedure. The objective of this article was to assess the utility of an optical microscope which gives magnification of up to 40x and gives clear picture of the surface of the stones. In order to authenticate the morphological analysis of urinary stones, SEM and elemental distribution analysis were performed. A total of 250 urinary stones of different compositions were collected from stone clinic, photographed, observed under an optical microscope, and optical photographs were taken at different angles. Twenty-five representative samples among these were gold sputtered to make them conductive and were fed into the SEM machine. Photographs of the samples were taken at different angles at magnifications up to 4,000. Elemental distribution analysis (EDAX) was done to confirm the composition. The observations of the two studies were compared. The different appearances of the stones under optical illuminated microscopy were mostly standardized appearances, namely bosselations of pure whewellite, spiculations of weddellite, bright yellow colored appearance of uric acid, and dirty white amorphous appearance of phosphates. SEM and EDAX gave clearer pictures and gave added confirmation of the stone composition. From the references thus obtained, it was possible to confirm the composition by studying the optical microscopic pictures. Higher magnification capacity of the SEM and the EDAX patterns are useful to give reference support for performing optical microscopy work. After standardization, routine analysis can be performed with optical microscopy. The advantage of the optical microscope is that, it

  17. Scanning Probe Evaluation of Electronic, Mechanical and Structural Material Properties

    NASA Astrophysics Data System (ADS)

    Virwani, Kumar

    2011-03-01

    We present atomic force microscopy (AFM) studies of a range of properties from three different classes of materials: mixed ionic electronic conductors, low-k dielectrics, and polymer-coated magnetic nanoparticles. (1) Mixed ionic electronic conductors are being investigated as novel diodes to drive phase-change memory elements. Their current-voltage characteristics are measured with direct-current and pulsed-mode conductive AFM (C-AFM). The challenges to reliability of the C-AFM method include the electrical integrity of the probe, the sample and the contacts, and the minimization of path capacitance. The role of C-AFM in the optimization of these electro-active materials will be presented. (2) Low dielectric constant (low-k) materials are used in microprocessors as interlayer insulators, a role directly affected by their mechanical performance. The mechanical properties of nanoporous silicate low-k thin films are investigated in a comparative study of nanomechanics measured by AFM and by traditional nanoindentation. Both methods are still undergoing refinement as reliable analytical tools for determining nanomechanical properties. We will focus on AFM, the faster of the two methods, and its developmental challenges of probe shape, cantilever force constant, machine compliance and calibration standards. (3) Magnetic nanoparticles are being explored for their use in patterned media for magnetic storage. Current methods for visualizing the core-shell structure of polymer-coated magnetic nanoparticles include dye-staining the polymer shell to provide contrast in transmission electron microscopy. AFM-based fast force-volume measurements provide direct visualization of the hard metal oxide core within the soft polymer shell based on structural property differences. In particular, the monitoring of adhesion and deformation between the AFM tip and the nanoparticle, particle-by-particle, provides a reliable qualitative tool to visualize core-shell contrast without the use

  18. 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.

  19. Direct-write liquid phase transformations with a scanning transmission electron microscope

    DOE PAGES

    Unocic, Raymond R.; Lupini, Andrew R.; Borisevich, Albina Y.; ...

    2016-08-03

    The highly energetic electron beam from a scanning transmission electron microscope (STEM) can induce local changes in the state of matter, ranging from local knock-out and atomic movement, to amorphization/crystallization, and chemical/electrochemical reactions occuring at localized liquid-solid and gas-solid interfaces. To date, fundamental studies of e-beam induced phenomena and practical applications have been limited by conventional e-beam rastering modes that allow only for uniform e-beam exposures. Here we develop an automated liquid phase nanolithography method that is capable of directly writing nanometer scaled features within silicon nitride encapsulated liquid cells. An external beam control system, connected to the scan coilsmore » of an aberration-corrected STEM, is used to precisely control the position, dwell time, and scan velocity of a sub-nanometer STEM probe. Site-specific locations in a sealed liquid cell containing an aqueous solution of H2PdCl4 are irradiated to controllably deposit palladium onto silicon nitride membranes. We determine the threshold electron dose required for the radiolytic deposition of metallic palladium, explore the influence of electron dose on the feature size and morphology of nanolithographically patterned nanostructures, and propose a feedback-controlled monitoring method for active control of the nanofabricated structures through STEM detector signal monitoring. As a result, this approach enables both fundamental studies of electron beam induced interactions with matter, as well as opens a pathway to fabricate nanostructures with tailored architectures and chemistries via shape-controlled nanolithographic patterning from liquid phase precursors.« less

  20. Direct-write liquid phase transformations with a scanning transmission electron microscope

    SciTech Connect

    Unocic, Raymond R.; Lupini, Andrew R.; Borisevich, Albina Y.; Cullen, David A.; Kalinin, Sergei V.; Jesse, Stephen

    2016-08-03

    The highly energetic electron beam from a scanning transmission electron microscope (STEM) can induce local changes in the state of matter, ranging from local knock-out and atomic movement, to amorphization/crystallization, and chemical/electrochemical reactions occuring at localized liquid-solid and gas-solid interfaces. To date, fundamental studies of e-beam induced phenomena and practical applications have been limited by conventional e-beam rastering modes that allow only for uniform e-beam exposures. Here we develop an automated liquid phase nanolithography method that is capable of directly writing nanometer scaled features within silicon nitride encapsulated liquid cells. An external beam control system, connected to the scan coils of an aberration-corrected STEM, is used to precisely control the position, dwell time, and scan velocity of a sub-nanometer STEM probe. Site-specific locations in a sealed liquid cell containing an aqueous solution of H2PdCl4 are irradiated to controllably deposit palladium onto silicon nitride membranes. We determine the threshold electron dose required for the radiolytic deposition of metallic palladium, explore the influence of electron dose on the feature size and morphology of nanolithographically patterned nanostructures, and propose a feedback-controlled monitoring method for active control of the nanofabricated structures through STEM detector signal monitoring. As a result, this approach enables both fundamental studies of electron beam induced interactions with matter, as well as opens a pathway to fabricate nanostructures with tailored architectures and chemistries via shape-controlled nanolithographic patterning from liquid phase precursors.

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

    SciTech Connect

    Prabhakaran, Ramprashad; Joshi, Vineet V.; Rhodes, Mark A.; Schemer-Kohrn, Alan L.; Guzman, Anthony D.; Lavender, Curt 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.

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

    SciTech Connect

    Prabhakaran, Ramprashad; Joshi, Vineet V.; Rhodes, Mark A.; Schemer-Kohrn, Alan L.; Guzman, Anthony D.; Lavender, Curt 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.

  3. Bright-field scanning confocal electron microscopy using a double aberration-corrected transmission electron microscope.

    PubMed

    Wang, Peng; Behan, Gavin; Kirkland, Angus I; Nellist, Peter D; Cosgriff, Eireann C; D'Alfonso, Adrian J; Morgan, Andrew J; Allen, Leslie J; Hashimoto, Ayako; Takeguchi, Masaki; Mitsuishi, Kazutaka; Shimojo, Masayuki

    2011-06-01

    Scanning confocal electron microscopy (SCEM) offers a mechanism for three-dimensional imaging of materials, which makes use of the reduced depth of field in an aberration-corrected transmission electron microscope. The simplest configuration of SCEM is the bright-field mode. In this paper we present experimental data and simulations showing the form of bright-field SCEM images. We show that the depth dependence of the three-dimensional image can be explained in terms of two-dimensional images formed in the detector plane. For a crystalline sample, this so-called probe image is shown to be similar to a conventional diffraction pattern. Experimental results and simulations show how the diffracted probes in this image are elongated in thicker crystals and the use of this elongation to estimate sample thickness is explored.

  4. Metal particles in a ceramic matrix--scanning electron microscopy and transmission electron microscopy characterization.

    PubMed

    Konopka, K

    2006-09-01

    This paper is concerned with ceramic matrix (Al(2)O(3)) composites with introduced metal particles (Ni, Fe). The composites were obtained via sintering of powders under very high pressure (2.5 GPa). Scanning electron microscopy and transmission electron microscopy were chosen as the tools for the identification and description of the shape, size and distribution of the metal particles. The Al(2)O(3)-Ni composite contained agglomerates of the Ni particles surrounded by ceramic grains and nanometre-size Ni particles located inside the ceramic grains and at the ceramic grain boundaries. In the Al(2)O(3)-Fe composite, the Fe particles were mostly surrounded by ceramic grains. Moreover, holes left by the Fe particles were found. The high pressure used in the fabrication of the composites changed the shape of the metal and ceramic powder grains via plastic deformation.

  5. Scanning electron microscopic evaluation of the effects of intracameral injection of cyanoacrylate in the rabbit.

    PubMed

    Macsai, M; Kuczak, J; Robin, J B

    1990-01-01

    We examined, using scanning electron microscopy, the effects of the injection of an isobutyl cyanoacrylate into the rabbit anterior chamber. Injection of the adhesive produced a rapidly polymerized mass that remained in the anterior chamber throughout the course of the study. Additionally, an active inflammatory response was noted in the anterior chamber, characterized by a progressively enlarging "cocoon" of fibrin and inflammatory cells surrounding the polymerized adhesive, as well as inflammatory cells in the trabecular meshwork. Following cyanoacrylate injection, the corneal endothelial cells were noted to be swollen for the first 14 days of the study.

  6. Scanning electron microscopy of the orbital Harderian gland in the male Atlantic bottlenose dolphin (Tursiops truncatus).

    PubMed

    Ortiz, G G; Feria-Velasco, A; Pacheco-Moisés, F P; Rodríguez-Reinoso, S; Cruz-Ramos, J A; Rosales-Corral, S A; Reiter, R J

    2009-08-01

    The ultrastructure of the Harderian gland of Atlantic bottlenose dolphin (Tursiops truncatus) was examined by scanning electron microscopy (SEM). We found the following surface features: the typical round appearance of the ascinar glandular unit with a finely granular surface, a thin cortex and immediately below two types of cells: type I cells (characterized by small lipid vacuoles) and type II cells (characterized by large lipid vacuoles). It has been suggested that different cells forms represent a single cell type in varying activity states. Additionally, a coalescent tubular complex, a small balloon-like structures and large globular structures were observed. These structures may be reservoirs of secretion products.

  7. Sample thickness determination by scanning transmission electron microscopy at low electron energies.

    PubMed

    Volkenandt, Tobias; Müller, Erich; Gerthsen, Dagmar

    2014-02-01

    Sample thickness is a decisive parameter for any quantification of image information and composition in transmission electron microscopy. In this context, we present a method to determine the local sample thickness by scanning transmission electron microscopy at primary energies below 30 keV. The image intensity is measured with respect to the intensity of the incident electron beam and can be directly compared with Monte Carlo simulations. Screened Rutherford and Mott scattering cross-sections are evaluated with respect to fitting experimental data with simulated image intensities as a function of the atomic number of the sample material and primary electron energy. The presented method is tested for sample materials covering a wide range of atomic numbers Z, that is, fluorenyl hexa-peri-hexabenzocoronene (Z = 3.5), carbon (Z = 6), silicon (Z = 14), gallium nitride (Z = 19), and tungsten (Z = 74). Investigations were conducted for two primary energies (15 and 30 keV) and a sample thickness range between 50 and 400 nm.

  8. A method of dynamic chromatic aberration correction in low-voltage scanning electron microscopes.

    PubMed

    Khursheed, Anjam

    2005-07-01

    A time-of-flight concept that dynamically corrects for chromatic aberration effects in scanning electron microscopes (SEMs) is presented. The method is predicted to reduce the microscope's chromatic aberration by an order of magnitude. The scheme should significantly improve the spatial resolution of low-voltage scanning electron microscopes (LVSEMs). The dynamic means of correcting for chromatic aberration also allows for the possibility of obtaining high image resolution from electron guns that have relatively large energy spreads.

  9. Practical spatial resolution of electron energy loss spectroscopy in aberration corrected scanning transmission electron microscopy.

    PubMed

    Shah, A B; Ramasse, Q M; Wen, J G; Bhattacharya, A; Zuo, J M

    2011-08-01

    The resolution of electron energy loss spectroscopy (EELS) is limited by delocalization of inelastic electron scattering rather than probe size in an aberration corrected scanning transmission electron microscope (STEM). In this study, we present an experimental quantification of EELS spatial resolution using chemically modulated 2×(LaMnO(3))/2×(SrTiO(3)) and 2×(SrVO(3))/2×(SrTiO(3)) superlattices by measuring the full width at half maxima (FWHM) of integrated Ti M(2,3), Ti L(2,3), V L(2,3), Mn L(2,3), La N(4,5), La N(2,3) La M(4,5) and Sr L(3) edges over the superlattices. The EELS signals recorded using large collection angles are peaked at atomic columns. The FWHM of the EELS profile, obtained by curve-fitting, reveals a systematic trend with the energy loss for the Ti, V, and Mn edges. However, the experimental FWHM of the Sr and La edges deviates significantly from the observed experimental tendency.

  10. Reproducible strain measurement in electronic devices by applying integer multiple to scanning grating in scanning moiré fringe imaging

    SciTech Connect

    Kim, Suhyun Jung, Younheum; Kim, Joong Jung; Lee, Sunyoung; Lee, Haebum; Kondo, Yukihito

    2014-10-15

    Scanning moiré fringe (SMF) imaging by high-angle annular dark field scanning transmission electron microscopy was used to measure the strain field in the channel of a transistor with a CoSi{sub 2} source and drain. Nanometer-scale SMFs were formed with a scanning grating size of d{sub s} at integer multiples of the Si crystal lattice spacing d{sub l} (d{sub s} ∼ nd{sub l}, n = 2, 3, 4, 5). The moiré fringe formula was modified to establish a method for quantifying strain measurement. We showed that strain fields in a transistor measured by SMF images were reproducible with an accuracy of 0.02%.

  11. Scanning tunneling microscopy investigations of hydrogen plasma-induced electron scattering centers on single-walled carbon nanotubes

    SciTech Connect

    Buchs, G.; Ruffieux, P.; Groening, P.; Groening, O. . E-mail: nanotech@surfaces

    2007-01-01

    The authors report on the generation of localized defects on single-walled carbon nanotubes by means of a hydrogen electron cyclotron resonance plasma. The defects have been investigated using scanning tunneling microscopy (STM) and show an apparent topographic height in the STM of 1-3 A. In the vicinity of defects, characteristic superstructures could be observed and the patterns could be simulated using a simple model based on large momentum scattering of the valence electrons. The combination of low structural damage and high electronic activity opens the possibility to tune the electronic transport properties using such defects.

  12. Design of a fast electron beam scanning system for compact synchrotron light sources

    NASA Astrophysics Data System (ADS)

    Moser, H. O.; Lehr, H.

    1989-07-01

    The design of an electron beam scanning system for compact storage ring synchrotron light sources is described. The main features are a scan frequency of 100 Hz and an angular amplitude of ±5 mrad. Different configurations of scan dipoles permit confining the scan to one cell using four dipoles or to repeat the scan periodically along the whole circumference by means of two scan dipoles per cell. Combinations of these basic configurations are possible. The location of the nodes of the pivoting electron beam can be optimized with respect to the maximum scan angle by slightly unbalancing the field strength in different scan dipoles. The scan dipoles are H-shaped magnets made from laminated iron. Their gap width is 68 mm. They are powered by fast transistor-bridge supplies which are controlled by freely programmable function generators capable of realizing a triangular current waveform with a deviation of less than 0.1% except for a 1% neighborhood of the apex. Estimates of the influence of the scanning on both quantum and Coulomb lifetime indicate acceptable lifetime reductions provided the minimum distance between distorted closed orbit and aperture exceeds about six standard deviations of the spatial electron distribution.

  13. Active Well Coincidence Counter measurements of enriched uranium fuel assemblies in scanning and stationary modes

    SciTech Connect

    Krick, M.S.; Cowder, L. ); Maltsev, V.; Chernikov, A.; Mokeenko, P.; D'yadkov, K.; Ivanov, V. Nuclear Power Plant, Zarechnyy ); Lagattu, A.; Lopatin, Y.; Czock, K.; Rundquist, D.; Pedraza, L. )

    1991-01-01

    Enriched uranium fuel assemblies were measured with an Active Well Coincidence Counter (AWCC) at the Beloyarskaya Nuclear Power Plant. Special AWCC inserts, electronics, and software were used. Stationary and scanning measurements were performed to establish calibrations and performance specifications for the assay of {sup 235}U and {sub 235}U/cm for BN600 fuel. 6 refs., 7 figs., 2 tabs.

  14. 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.

  15. Stochastic Micro-Pattern for Automated Correlative Fluorescence - Scanning Electron Microscopy

    PubMed Central

    Begemann, Isabell; Viplav, Abhiyan; Rasch, Christiane; Galic, Milos

    2015-01-01

    Studies of cellular surface features gain from correlative approaches, where live cell information acquired by fluorescence light microscopy is complemented by ultrastructural information from scanning electron micrographs. Current approaches to spatially align fluorescence images with scanning electron micrographs are technically challenging and often cost or time-intensive. Relying exclusively on open-source software and equipment available in a standard lab, we have developed a method for rapid, software-assisted alignment of fluorescence images with the corresponding scanning electron micrographs via a stochastic gold micro-pattern. Here, we provide detailed instructions for micro-pattern production and image processing, troubleshooting for critical intermediate steps, and examples of membrane ultra-structures aligned with the fluorescence signal of proteins enriched at such sites. Together, the presented method for correlative fluorescence – scanning electron microscopy is versatile, robust and easily integrated into existing workflows, permitting image alignment with accuracy comparable to existing approaches with negligible investment of time or capital. PMID:26647824

  16. 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...

  17. 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.

  18. 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.

  19. Scanning Electron Microscopy Investigation of a Sample Depth Profile Through the Martian Meteorite Nakhla

    NASA Technical Reports Server (NTRS)

    Toporski, Jan; Steele, Andrew; Westall, Frances; McKay, David S.

    2000-01-01

    The ongoing scientific debate as to whether or not the Martian meteorite ALH84001 contained evidence of possible biogenic activities showed the need to establish consistent methods to ascertain the origin of such evidence. To distinguish between terrestrial organic material/microbial contaminants and possible indigenous microbiota within meteorites is therefore crucial. With this in mind a depth profile consisting of four samples from a new sample allocation of Martian meteorite Nakhla was investigated using scanning electron microscopy (SEM) and energy dispersive X-ray analysis. SEM imaging of freshly broken fractured chips revealed structures strongly recent terrestrial microorganisms, in some cases showing evidence of active growth. This conclusion was supported by EDX analysis, which showed the presence of carbon associated with these structures, we concluded that these structures represent recent terrestrial contaminants rather than structures indigenous to the meteorite. Page

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

    SciTech Connect

    Zaka, F.

    2016-11-15

    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.

  1. Advantages of Environmental Scanning Electron Microscopy in Studies of Microorganisms

    DTIC Science & Technology

    1993-01-01

    disruption of sporangia. Uncoated algal cells of Euglena gracilis and Spirogyra sp. were examined using the backscatter electron detector (BSE) and the...agar. (Fig. 7). Uncoated, freeze-dried Euglena sp. cells exam- ined with either ESD or BSE detectors did not exhibit Specimen Preparation for ESEM...P.L. (1967) Observations in the fine struc- Biofilms: An ESEM evaluation of artifacts introduced during SEM ture of the pellicle pores of Euglena

  2. Identification of fly eggs using scanning electron microscopy for forensic investigations.

    PubMed

    Mendonça, Paloma Martins; dos Santos-Mallet, Jacenir Reis; de Mello, Rubens Pinto; Gomes, Leonardo; de Carvalho Queiroz, Margareth Maria

    2008-10-01

    Forensic entomology is the science that studies the role of insects in decomposing corpses and one of the most common uses is to estimate the post-mortem interval (PMI) based on insect activity on a decomposing body. Usually, flies are the first insects to reach a carcass and are able to oviposit on carrion within a few hours after death. Scanning electron microscopy (SEM) gives detailed information about morphological characters helping to identify the immature forms of flies and consequently serves as a tool in crime scene investigations. Sometimes, only eggs and larvae are found in corpses. Some dipteral species are important because their larvae develop in organic matter. The aim of this study is to identify eggs of species of forensic importance, such as Chrysomya megacephala, Chrysomya putoria, Lucilia cuprina, Lucilia eximia and Ophyra aenescens, using scanning electron microscopy (SEM). C. megacephala had no anastomosis or holes at the top of the islands and C. putoria had few anastomoses and no holes, whereas L. eximia and O. aenescens were found to have anastomoses and holes and L. cuprina had only anastomoses. The median area was bifurcated anteriorly in C. megacephala, L. eximia and O. aenescens and rounded in C. putoria and L. cuprina. Also the sculptures observed in the chorionic cells, the length and the way that median area ends up posteriorly are characteristics of great diagnostic value to identify muscoids of forensic importance.

  3. Microcomputer-Assisted Biomass Determination of Plankton Bacteria on Scanning Electron Micrographs

    PubMed Central

    Krambeck, Christiane; Krambeck, Hans-Jürgen; Overbeck, Jürgen

    1981-01-01

    Although biovolume is a better measure of biomass than is cell number, biovolumes have rarely been measured because their evaluation is extremely time-consuming. We developed a microcomputer system that assists cell size measurements on images of filtered plankton: scanning electron micrograph negatives were projected on a digitizer field, bacterial length and width were marked by a cursor, and coordinates were directly transferred to an MOS 6502 microcomputer (KIM 1). The dialogue program BABI organized and controlled the digitizer measurements in cooperation with the user, enabled corrections, and printed out results with 95% confidence limits and sample description. The time for scanning electron micrograph preparation was reduced to 15 min (quick transfer to Freon 113 during filtration and air drying). Altogether, this biovolume determination took about 2.5 h for confidence limits of ±15%. Examples are given for applications of the method: (i) comparison of 10 lakes (with specific activities for glucose uptake and for heterotrophic CO2 fixation); (ii) ranges of biomass parameters in one lake; (iii) diurnal cycles (with synchronizing effects, uptake of algal exudates, and calculation of daily growth). This method is discussed in relation to other biomass methods (epifluorescent microscopy, lipopolysaccharide technique, frequency of dividing cells) and the problem of biovolume-to-carbon conversions. Images PMID:16345807

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

    SciTech Connect

    Sudheer, Tiwari, P.; Rai, V. N.; Srivastava, A. K.; Mukharjee, C.

    2015-06-24

    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.

  5. Ultrastructural analysis of testicular tissue and sperm by transmission and scanning electron microscopy.

    PubMed

    Chemes, Hector E

    2013-01-01

    Transmission electron microscopy (TEM) studies have provided the basis for an in-depth understanding of the cell biology and normal functioning of the testis and male gametes and have opened the way to characterize the functional role played by specific organelles in spermatogenesis and sperm function. The development of the scanning electron microscope (SEM) extended these boundaries to the recognition of cell and organ surface features and the architectural array of cells and tissues. The merging of immunocytochemical and histochemical approaches with electron microscopy has completed a series of technical improvements that integrate structural and functional features to provide a broad understanding of cell biology in health and disease. With these advances the detailed study of the intricate structural and molecular organization as well as the chemical composition of cellular organelles is now possible. Immunocytochemistry is used to identify proteins or other components and localize them in specific cells or organelles with high specificity and sensitivity, and histochemistry can be used to understand their function (i.e., enzyme activity). When these techniques are used in conjunction with electron microscopy their resolving power is further increased to subcellular levels. In the present chapter we will describe in detail various ultrastructural techniques that are now available for basic or translational research in reproductive biology and reproductive medicine. These include TEM, ultrastructural immunocytochemistry, ultrastructural histochemistry, and SEM.

  6. Modeling a Miniaturized Scanning Electron Microscope Focusing Column - Lessons Learned in Electron Optics Simulation

    NASA Technical Reports Server (NTRS)

    Loyd, Jody; Gregory, Don; Gaskin, Jessica

    2016-01-01

    This presentation discusses work done to assess the design of a focusing column in a miniaturized Scanning Electron Microscope (SEM) developed at the NASA Marshall Space Flight Center (MSFC) for use in-situ on the Moon-in particular for mineralogical analysis. The MSFC beam column design uses purely electrostatic fields for focusing, because of the severe constraints on mass and electrical power consumption imposed by the goals of lunar exploration and of spaceflight in general. The resolution of an SEM ultimately depends on the size of the focused spot of the scanning beam probe, for which the stated goal here is a diameter of 10 nanometers. Optical aberrations are the main challenge to this performance goal, because they blur the ideal geometrical optical image of the electron source, effectively widening the ideal spot size of the beam probe. In the present work the optical aberrations of the mini SEM focusing column were assessed using direct tracing of non-paraxial rays, as opposed to mathematical estimates of aberrations based on paraxial ray-traces. The geometrical ray-tracing employed here is completely analogous to ray-tracing as conventionally understood in the realm of photon optics, with the major difference being that in electron optics the lens is simply a smoothly varying electric field in vacuum, formed by precisely machined electrodes. Ray-tracing in this context, therefore, relies upon a model of the electrostatic field inside the focusing column to provide the mathematical description of the "lens" being traced. This work relied fundamentally on the boundary element method (BEM) for this electric field model. In carrying out this research the authors discovered that higher accuracy in the field model was essential if aberrations were to be reliably assessed using direct ray-tracing. This led to some work in testing alternative techniques for modeling the electrostatic field. Ultimately, the necessary accuracy was attained using a BEM

  7. Photoemission electron microscopy and scanning electron microscopy of Magnetospirillum magnetotacticum’s magnetosome chains

    SciTech Connect

    Keutner, Christoph; von Bohlen, Alex; Berges, Ulf; Espeter, Philipp; Schneider, Claus M.; Westphal, Carsten

    2014-10-07

    Magnetotactic bacteria are of great interdisciplinary interest, since a vast field of applications from magnetic recording media to medical nanorobots is conceivable. A key feature for a further understanding is the detailed knowledge about the magnetosome chain within the bacteria. We report on two preparation procedures suitable for UHV experiments in reflective geometry. Further, we present the results of scanning electron microscopy, as well as the first photoemission electron microscopy experiments, both accessing the magnetosomes within intact magnetotactic bacteria and compare these to scanning electron microscopy data from the literature. From the images, we can clearly identify individual magnetosomes within their chains.

  8. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography

    PubMed Central

    Jesse, S.; Chi, M.; Belianinov, A.; Beekman, C.; Kalinin, S. V.; Borisevich, A. Y.; Lupini, A. R.

    2016-01-01

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy. PMID:27211523

  9. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography

    SciTech Connect

    Jesse, S.; Chi, M.; Belianinov, A.; Beekman, C.; Kalinin, S. V.; Borisevich, A. Y.; Lupini, A. R.

    2016-05-23

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. In this paper, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. Finally, however, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.

  10. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography

    DOE PAGES

    Jesse, S.; Chi, M.; Belianinov, A.; ...

    2016-05-23

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. In this paper, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature andmore » does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. Finally, however, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.« less

  11. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography.

    PubMed

    Jesse, S; Chi, M; Belianinov, A; Beekman, C; Kalinin, S V; Borisevich, A Y; Lupini, A R

    2016-05-23

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called "big-data" methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.

  12. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography

    NASA Astrophysics Data System (ADS)

    Jesse, S.; Chi, M.; Belianinov, A.; Beekman, C.; Kalinin, S. V.; Borisevich, A. Y.; Lupini, A. R.

    2016-05-01

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.

  13. Correlative analysis of immunoreactivity in confocal laser-scanning microscopy and scanning electron microscopy with focused ion beam milling.

    PubMed

    Sonomura, Takahiro; Furuta, Takahiro; Nakatani, Ikuko; Yamamoto, Yo; Unzai, Tomo; Matsuda, Wakoto; Iwai, Haruki; Yamanaka, Atsushi; Uemura, Masanori; Kaneko, Takeshi

    2013-01-01

    Recently, three-dimensional reconstruction of ultrastructure of the brain has been realized with minimal effort by using scanning electron microscopy (SEM) combined with focused ion beam (FIB) milling (FIB-SEM). Application of immunohistochemical staining in electron microscopy (EM) provides a great advantage in that molecules of interest are specifically localized in ultrastructures. Thus, we applied immunocytochemistry for FIB-SEM and correlated this immunoreactivity with that in confocal laser-scanning microcopy (CF-LSM). Dendrites of medium-sized spiny neurons in the rat neostriatum were visualized using a recombinant viral vector, which labeled the infected neurons with membrane-targeted GFP in a Golgi stain-like fashion. Moreover, the thalamostriatal afferent terminals were immunolabeled with Cy5 fluorescence for vesicular glutamate transporter 2 (VGluT2). After detection of the sites of terminals apposed to the dendrites by using CF-LSM, GFP and VGluT2 immunoreactivities were further developed for EM by using immunogold/silver enhancement and immunoperoxidase/diaminobenzidine (DAB) methods, respectively. In contrast-inverted FIB-SEM images, silver precipitations and DAB deposits were observed as fine dark grains and diffuse dense profiles, respectively, indicating that these immunoreactivities were as easily recognizable as those in the transmission electron microscopy (TEM) images. Furthermore, in the sites of interest, some appositions displayed synaptic specializations of an asymmetric type. Thus, the present method was useful in the three-dimensional analysis of immunocytochemically differentiated synaptic connections in the central neural circuit.

  14. 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.

  15. Space-time ambiguity functions for electronically scanned ISR applications

    NASA Astrophysics Data System (ADS)

    Swoboda, John; Semeter, Joshua; Erickson, Philip

    2015-05-01

    Electronically steerable array (ESA) technology has recently been applied to incoherent scatter radar (ISR) systems. These arrays allow for pulse-to-pulse steering of the antenna beam to collect data in a three-dimensional region. This is in direct contrast to dish-based antennas, where ISR acquisition is limited at any one time to observations in a two-dimensional slice. This new paradigm allows for more flexibility in the measurement of ionospheric plasma parameters. Multiple ESA-based ISR systems operate currently in the high-latitude region where the ionosphere is highly variable in both space and time. Because of the highly dynamic nature of the ionosphere in this region, it is important to differentiate between measurement-induced artifacts and the true behavior of the plasma. Often, three-dimensional ISR data produced by ESA systems are fitted in a spherical coordinate space and then the parameters are interpolated to a Cartesian grid, potentially introducing error and impacting the reconstructions of the plasma parameters. To take advantage of the new flexibility inherent in ESA systems, we present a new way of analyzing ISR observations through use of the space-time ambiguity function. The use of this new measurement ambiguity function allows us to pose the ISR observational problem in terms of a linear inverse problem whose goal is the estimate of the time domain lags of the intrinsic plasma autocorrelation function used for parameter fitting. The framework allows us to explore the impact of nonuniformity in plasma parameters in both time and space. We discuss examples of possible artifacts in high-latitude situations and discuss possible ways of reducing them and improving the quality of data products from electronically steerable ISRs.

  16. Scanning Electron Microscopy (SEM) Procedure for HE Powders on a LEO 438VP System

    SciTech Connect

    Zaka, Fowzia

    2016-03-21

    This method describes the characterization of HE powders by Scanning Electron Microscopy (SEM). HE particles are dispersed onto an aluminum standard SEM specimen mount. Electron micrographs are collected at various magnifications (150 to 10,000 X) depending on HE particle size.

  17. Scanning Electron Microscopy (SEM) Procedure for HE Powders on a LEO 438VP System

    SciTech Connect

    Zaka, Fowzia

    2016-03-08

    This method describes the characterization of HE powders by Scanning Electron Microscopy (SEM). HE particles are dispersed onto an aluminum standard SEM specimen mount. Electron micrographs are collected at various magnifications (150 to 10,000 X) depending on HE particle size.

  18. 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.

  19. Strain measurement in semiconductor heterostructures by scanning transmission electron microscopy.

    PubMed

    Müller, Knut; Rosenauer, Andreas; Schowalter, Marco; Zweck, Josef; Fritz, Rafael; Volz, Kerstin

    2012-10-01

    This article deals with the measurement of strain in semiconductor heterostructures from convergent beam electron diffraction patterns. In particular, three different algorithms in the field of (circular) pattern recognition are presented that are able to detect diffracted disc positions accurately, from which the strain in growth direction is calculated. Although the three approaches are very different as one is based on edge detection, one on rotational averages, and one on cross correlation with masks, it is found that identical strain profiles result for an In x Ga1-x N y As1-y /GaAs heterostructure consisting of five compressively and tensile strained layers. We achieve a precision of strain measurements of 7-9·10-4 and a spatial resolution of 0.5-0.7 nm over the whole width of the layer stack which was 350 nm. Being already very applicable to strain measurements in contemporary nanostructures, we additionally suggest future hardware and software designs optimized for fast and direct acquisition of strain distributions, motivated by the present studies.

  20. Scanning and Transmission Electron Microscopy of High Temperature Materials

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Software and hardware updates to further extend the capability of the electron microscope were carried out. A range of materials such as intermetallics, metal-matrix composites, ceramic-matrix composites, ceramics and intermetallic compounds, based on refractory elements were examined under this research. Crystal structure, size, shape and volume fraction distribution of various phases which constitute the microstructures were examined. Deformed materials were studied to understand the effect of interfacial microstructure on the deformation and fracture behavior of these materials. Specimens tested for a range of mechanical property requirements, such as stress rupture, creep, low cycle fatigue, high cycle fatigue, thermomechanical fatigue, etc. were examined. Microstructural and microchemical stability of these materials exposed to simulated operating environments were investigated. The EOIM Shuttle post-flight samples were also examined to understand the influence of low gravity processing on microstructure. In addition, fractographic analyses of Nb-Zr-W, titanium aluminide, molybdenum silicide and silicon carbide samples were carried out. Extensive characterization of sapphire fibers in the fiber-reinforced composites made by powder cloth processing was made. Finally, pressure infiltration casting of metal-matrix composites was carried out.

  1. Scanning Electron Microscopic Studies of the Pecten Oculi in the Quail (Coturnix coturnix japonica)

    PubMed Central

    Pourlis, Aris F.

    2013-01-01

    The main purpose of this study is to extend the microscopic investigations of the pecten oculi in the quail in order to add some information on the unresolved functional anatomy of this unique avian organ. The pecten oculi of the quail was studied by scanning electron microscopy. Eighteen- to-twenty two highly vascularised accordion-like folds were joined apically by a heavily pigmented bridge of tissue, which holds the pecten in a fanlike shape, widest at the base. The structure of the double layered limiting membrane was recorded. The presence of hyalocytes with macrophage-like appearance was illustrated. It is assumed that the pecten oculi of the quail resembles that of the chicken. Illustrated morphological features of this species may add information on the active physiological role of the pecten. But still, the functional significance of this organ is a matter of controversies. PMID:24198967

  2. Monte Carlo modeling of cavity imaging in pure iron using back-scatter electron scanning microscopy

    NASA Astrophysics Data System (ADS)

    Yan, Qiang; Gigax, Jonathan; Chen, Di; Garner, F. A.; Shao, Lin

    2016-11-01

    Backscattered electrons (BSE) in a scanning electron microscope (SEM) can produce images of subsurface cavity distributions as a nondestructive characterization technique. Monte Carlo simulations were performed to understand the mechanism of void imaging and to identify key parameters in optimizing void resolution. The modeling explores an iron target of different thicknesses, electron beams of different energies, beam sizes, and scan pitch, evaluated for voids of different sizes and depths below the surface. The results show that the void image contrast is primarily caused by discontinuity of energy spectra of backscattered electrons, due to increased outward path lengths for those electrons which penetrate voids and are backscattered at deeper depths. Size resolution of voids at specific depths, and maximum detection depth of specific voids sizes are derived as a function of electron beam energy. The results are important for image optimization and data extraction.

  3. 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

  4. Mass-mapping of ECM macromolecules by scanning transmission electron microscopy.

    PubMed

    Sherratt, Michael J; Graham, Helen K; Kielty, Cay M; Holmes, David F

    2009-01-01

    In the scanning transmission electron microscope, the degree of electron scattering induced by biological specimens, such as ECM macromolecules, is dependent on the molecular mass. By calibrating the ratio of scattered to non-scattered electrons against a known mass standard, such as tobacco mosaic virus, it is possible to quantify absolute changes in both mass and mass distribution. These mass mapping approaches can provide important information on ECM assembly, organisation, and interactions which is not obtainable by other means.

  5. Understanding the structure of nanocatalysts with high resolution scanning/transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Francis, L. D.; Rivas, J.; José-Yacamán, M.

    2014-03-01

    Nanomaterials including nanoparticles, nanowires and nanotubes play an important role in heterogeneous catalysis. Thanks to the rapid improvement of the electron microscopic techniques and with the advent of aberration corrected electron microscopy as well as theoretical methodologies, the potential effects induced by nanocatalysts are better understood than before by unravelling their atomic structure. A brief introduction to advanced electron microscopic techniques namely aberration corrected scanning transmission electron microscopy (Cs-STEM) is presented and subsequently two examples of nanocatalysts are considered in the present review. The first example will focus on the study of bimetallic/core-shell nanoalloys. In heterogeneous catalysis, catalysts containing two or more metals might show significantly different catalytic properties compared to the parent metals and thus are widely utilized in several catalytic reactions. Atom-by-atom insights of the nanoalloy based catalysts ex: Au-Pd will be described in the present review using a combination of advanced electron microscopic and spectroscopic techniques. A related example on the understanding of bimetallic clusters by HAADF-STEM will also be presented in addition to nanoparticles. In the second case understanding the structure of transition metal chalcogenide based nanocatalysts by HRTEM and aberration corrected STEM, for the case of MoS2 will be discussed. MoS2-based catalysts serve as model catalysts and are employed in the hydrodesulphurisations (HDS) reactions in the removal of sulphur from gasoline and related petrochemical products. They have been studied in various forms including nanowires, nanotubes and nanoplates. Their structure, atomic insights and as a consequence elucidation of their corresponding catalytic activity are thus important.

  6. 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.

  7. 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.

  8. Pulsed and scanned carbon dioxide laser resurfacing 2 years after treatment: comparison by means of scanning electron microscopy.

    PubMed

    Trelles, Mario A; Garcia, Luisa; Rigau, Josepa; Allones, Inès; Velez, Marìano

    2003-05-01

    Studies have reported short-term and long-term (1-year) findings for laser skin resurfacing. Two of the most popular systems used for this procedure, the continuous-wave Sharplan 40C SilkTouch system and the pulsed Coherent 5000C UltraPulse system with a computer pattern generator, were previously compared for a range of follow-up times up to 1 year, using light microscopy and transmission electron microscopy. This study analyzed the 2-year morphological differences using scanning electron microscopy. Tissue samples were obtained from 10 patients (age range, 50 to 72 years; skin types II and III) who had undergone laser resurfacing 2 years previously. One half of the face of each patient had been treated with the continuous-wave system and the other half with the pulsed system. The samples were subjected to scanning electron microscopy. On the continuous-wave-treated side, significantly better dermal collagen organization was observed at 2 years, with plump-appearing fibers that were closely knit to form a compact structure. On the side treated with the pulsed system, the collagen fibers in the papillary dermis were more loosely arranged and appeared drier. In both the continuous-wave-treated and pulsed-treated areas, the epidermis appeared healthy and exhibited some signs of age-related deterioration, with slightly flatter plaques and somewhat more flaking keratin on the pulsed-treated side. Probably because of the greater degree of residual thermal damage associated with the continuous-wave system, at 2 years after treatment there was more prolific synthesis and better orientation of collagen fibers, which were maintained for longer times, compared with the pulsed-treated specimens.

  9. 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.

  10. Imaging of Nitroxides at 250 MHz using Rapid-Scan Electron Paramagnetic Resonance

    PubMed Central

    Biller, Joshua R.; Tseitlin, Mark; Quine, Richard W.; Rinard, George A.; Weismiller, Hilary A.; Elajaili, Hanan; Rosen, Gerald M.; Kao, Joseph P. Y.; Eaton, Sandra S.; Eaton, Gareth R.

    2014-01-01

    Projections for 2D spectral-spatial images were obtained by continuous wave and rapid-scan electron paramagnetic resonance using a bimodal cross-loop resonator at 251 MHz. The phantom consisted of three 4 mm tubes containing different 15N,2H-substituted nitroxides. Rapid-scan and continuous wave images were obtained with 5 min total acquisition times. For comparison, images also were obtained with 29 s acquisition time for rapid scan and 15 min for continuous wave. Relative to continuous wave projections obtained for the same data acquisition time, rapid-scan projections had significantly less low-frequency noise and substantially higher signal-to-noise at higher gradients. Because of the improved image quality for the same data acquisition time, linewidths could be determined more accurately from the rapid-scan images than from the continuous wave images. PMID:24650729

  11. Imaging of nitroxides at 250MHz using rapid-scan electron paramagnetic resonance.

    PubMed

    Biller, Joshua R; Tseitlin, Mark; Quine, Richard W; Rinard, George A; Weismiller, Hilary A; Elajaili, Hanan; Rosen, Gerald M; Kao, Joseph P Y; Eaton, Sandra S; Eaton, Gareth R

    2014-05-01

    Projections for 2D spectral-spatial images were obtained by continuous wave and rapid-scan electron paramagnetic resonance using a bimodal cross-loop resonator at 251MHz. The phantom consisted of three 4mm tubes containing different (15)N,(2)H-substituted nitroxides. Rapid-scan and continuous wave images were obtained with 5min total acquisition times. For comparison, images also were obtained with 29s acquisition time for rapid scan and 15min for continuous wave. Relative to continuous wave projections obtained for the same data acquisition time, rapid-scan projections had significantly less low-frequency noise and substantially higher signal-to-noise at higher gradients. Because of the improved image quality for the same data acquisition time, linewidths could be determined more accurately from the rapid-scan images than from the continuous wave images.

  12. Scanning electron microscopy of experimental Trichophyton mentagrophytes infections in guinea pig skin.

    PubMed Central

    Hutton, R D; Kerbs, S; Yee, K

    1978-01-01

    Trichophyton mentagrophytes invasion of guinea pig skin was examined by scanning electron microscopy. Biopsies were obtained daily for 12 days from experimental infection sites. Dermatophyte invasion, examined in detail by scanning electron microscopy of cross-sectioned, prefixed skin was evidenced by: the appearance of hyphae within the stratum corneum; follicular invasion by hyphae, which remained initially within the follicle wall; emergence of the hyphae from the wall into the follicular canal; proliferation of the fungus down the follicle, with furrowing of the follicle wall and hair shaft cuticle; penetration of hyphae into the hair shaft by subcuticular and transcuticular routes; and massive peripilar hyphal proliferation with arthrosporogenesis. A three-dimensional perception of the invasion sequence of a dermatophyte in guinea pig skin was obtained by scanning electron microscopy. Images PMID:711318

  13. Nanoelectrical probing with multiprobe SPM Systems compatible with scanning electron microscopes

    NASA Astrophysics Data System (ADS)

    Lewis, Aaron; Ignatov, Andrey; Taha, Hesham; Zhinoviev, Oleg; Komissar, Anatoly; Krol, Alexander; Lewis, David

    2011-03-01

    A scanning electron microscope compatible platform that permits multiprobe atomic force microscopy based nanoelectrical characterization will be described. To achieve such multiple parameter nanocharacterization with scanning electron microscope compatibility involves a number of innovations both in instrument and probe design. This presentation will focus on how these advances were achieved and the results obtained with such instrumentation on electrical nano-characterization and electrical nano-manipulation. The advances include: 1. Specialized scanners; 2. An ultrasensitive feedback mechanism based on tuning forks with no optical feedback interference that can induce carriers in semiconductor devices; and 3. Unique probes compatible with multiprobe geometries in which the probe tips can be brought into physical contact with one another. Experiments will be described with such systems that will include multiprobe electrical measurements with metal and glass coated coaxial nanowires of platinum. This combination of scanning electron microscopes integrated with multiprobe instrumentation allows for important applications not available today in the field of semiconductor processing technology.

  14. Electrical characteristics of silicon nanowire transistors fabricated by scanning probe and electron beam lithographies.

    PubMed

    Ryu, Yu Kyoung; Chiesa, Marco; Garcia, Ricardo

    2013-08-09

    Silicon nanowire (SiNW) field-effect transistors have been fabricated by oxidation scanning probes and electron beam lithographies. The analysis and comparison of the electron mobility and subthreshold swing shows that the device performance is not affected by the top-down fabrication method. The two methods produce silicon nanowire transistors with similar electrical features, although oxidation scanning probe lithography generates nanowires with smaller channel widths. The values of the electron mobility and the subthreshold swing, 200 cm(2) V(-1) s(-1) and 500 mV dec(-1), respectively, are similar to those obtained from bottom-up methods. The compatibility of top-down methods with CMOS (complementary metal-oxide-semiconductor) procedures, the good electrical properties of the nanowire devices and the potential for making sub-10 nanowires, in particular by using oxidation scanning probe lithography, make those methods attractive for device fabrication.

  15. X-ray diffraction and scanning electron microscopy of galvannealed coatings on steel.

    PubMed

    Schmid, P; Uran, K; Macherey, F; Ebert, M; Ullrich, H-J; Sommer, D; Friedel, F

    2009-04-01

    The formation of Fe-Zn intermetallic compounds, as relevant in the commercial product galvannealed steel sheet, was investigated by scanning electron microscopy and different methods of X-ray diffraction. A scanning electron microscope with high resolution was applied to investigate the layers of the galvannealed coating and its topography. Grazing incidence X-ray diffraction (GID) was preferred over conventional Bragg-Brentano geometry for analysing thin crystalline layers because of its lower incidence angle alpha and its lower depth of information. Furthermore, in situ experiments at an environmental scanning electron microscope (ESEM) with an internal heating plate and at an X-ray diffractometer equipped with a high-temperature chamber were carried out. Thus, it was possible to investigate the phase evolution during heat treatment by X-ray diffraction and to display the growth of the zeta crystals in the ESEM.

  16. 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.

  17. 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.

  18. Differential Scanning Calorimetry (DSC) for the Analysis of Activated Carbon

    DTIC Science & Technology

    1991-10-01

    impregnation procedures . It is believed that Sutcliffe-Speakman is currently using coconut - shell as the carbon precursor (instead of the New Zealand coal...microstructure facilitate the adsorption process whereby all the undesirable materials are retained. For military deployment, the activated carbon is...AD-A245 899 H.P ’ l N dI dUenm / DIFFERENTIAL SCANNING CALORIMETRY (DSC) FOR THE ANALYSIS OF ACTIVATED CARBON (U) by S.H.C. a and L.E. Cameron DTIC x

  19. Use of Low Temperature Scanning Electron Microscopy to Observe Frozen Hydrated Specimens of Nematodes

    PubMed Central

    Wergin, William P.; Sayre, Richard M.; Erbe, Eric F.

    1993-01-01

    Frozen hydrated specimens of Pratylenchus agilis and dauer larvae of Steinernema carpocapsae were observed with low-temperature field emission scanning electron microscopy. This new technique provides information about the surface features of nematodes and also allows specimens to be fractured to reveal their internal structure. Furthermore, both halves of fractured specimens can be retained, examined, and photographed either as two-dimensional micrographs or as three-dimensional images for stereo observation (stereology) or quantitative measurements (stereometry). This technique avoids artifacts normally associated with procedures required to prepare nematodes for examination in the transmission and scanning electron microscopes, such as chemical fixation, dehydration, and sectioning or critical point drying. PMID:19279761

  20. Long range electronic transport in microbial nanowires bridging an electrode and scanned probe

    NASA Astrophysics Data System (ADS)

    Veazey, Joshua; Lampa-Pastirk, Sanela; Walsh, Kathy; Sun, Jiebing; Zhang, Pengpeng; Reguera, Gemma; Tessmer, Stuart

    2011-03-01

    The filament-like appendages known as pili, expressed by the bacterium Geobacter sulfurreducens, are believed to act as electrically conductive nanowires. Previously, we used scanning tunneling microscopy to study the local density of states at different positions along the wire. However, the long range electron transfer believed to occur in this protein has not been directly observed. Here we discuss a system for verifying long range transport using a scanning probe technique. Transport at distances of more than a few nanometers would require a novel biological electron transfer process. The authors gratefully acknowledge support from the National Science Foundation (MCB-1021948) and the Michigan State University Foundation (Strategic Partnership Grant).

  1. A compact multipurpose nanomanipulator for use inside a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Heeres, E. C.; Katan, A. J.; van Es, M. H.; Beker, A. F.; Hesselberth, M.; van der Zalm, D. J.; Oosterkamp, T. H.

    2010-02-01

    A compact, two-stage nanomanipulator was designed and built for use inside a scanning electron microscope. It consists of a fine stage employing piezostacks that provide a 15 μm range in three dimensions and a coarse stage based on commercially available stick-slip motors. Besides the fabrication of enhanced probes for scanning probe microscopy and the enhancement of electron field emitters, other novel manipulation processes were developed, such as locating, picking up, and positioning small nanostructures with an accuracy of ˜10 nm. In combination with in situ I-V experiments, welding, and etching, this results in a multipurpose nanofactory, enabling a new range of experiments.

  2. Scanning electron microscopy of the human endolymphatic sac: a preliminary report.

    PubMed

    Galey, F R; House, W F

    1980-04-01

    Scanning electron microscopy has been used to examine and compare one normal endolymphatic sac with one endolymphatic sac from a patient with Meniere's disease. The surgical procedure for obtaining these specimens and their preparation for scanning electron microscopy are described. The luminal surface of the rugose portion of both specimens was lined with two populations of epithelial cells: one with a dome-shaped apical surface, the other with a flattened polygonal surface. The surface of dome-shaped cells in both specimens was covered with microvilli. Neither specimen had observable loss of epithelial integrity or fibrosis.

  3. A novel approach to scanning electron microscopy at ambient atmospheric pressure.

    PubMed

    Ominami, Yusuke; Kawanishi, Shinsuke; Ushiki, Tatsuo; Ito, Sukehiro

    2015-04-01

    Scanning electron microscopy (SEM) for observing samples at ambient atmospheric pressure is introduced in this study. An additional specimen chamber with a small window is inserted in the main specimen chamber, and the window is separated with a thin membrane or diaphragm allowing electron beam propagation. Close proximity of the sample to the membrane enables the detection of back-scattered electrons sufficient for imaging. In addition to the empirical imaging data, a probability analysis of the un-scattered fraction of the incident electron beam further supports the feasibility of atmospheric SEM imaging over a controlled membrane-sample distance.

  4. Imaging correlated wave functions of few-electron quantum dots: Theory and scanning tunneling spectroscopy experimentsa)

    NASA Astrophysics Data System (ADS)

    Rontani, Massimo; Molinari, Elisa; Maruccio, Giuseppe; Janson, Martin; Schramm, Andreas; Meyer, Christian; Matsui, Tomohiro; Heyn, Christian; Hansen, Wolfgang; Wiesendanger, Roland

    2007-04-01

    We show both theoretically and experimentally that scanning tunneling spectroscopy (STS) images of semiconductor quantum dots may display clear signatures of electron-electron correlation. We apply many-body tunneling theory to a realistic model, which fully takes into account correlation effects and dot anisotropy. Comparing measured STS images of freestanding InAs quantum dots with those calculated by the full configuration interaction method, we explain the wave-function sequence in terms of images of one- and two-electron states. The STS map corresponding to double charging is significantly distorted by electron correlation with respect to the noninteracting case.

  5. Semi-empirical model for the generation of dose distributions produced by a scanning electron beam

    SciTech Connect

    Nath, R.; Gignac, C.E.; Agostinelli, A.G.; Rothberg, S.; Schulz, R.J.

    1980-01-01

    There are linear accelerators (Sagittaire and Saturne accelerators produced by Compagnie Generale de Radiologie (CGR/MeV) Corporation) which produce broad, flat electron fields by magnetically scanning the relatively narrow electron beam as it emerges from the accelerator vacuum system. A semi-empirical model, which mimics the scanning action of this type of accelerator, was developed for the generation of dose distributions in homogeneous media. The model employs the dose distributions of the scanning electron beams. These were measured with photographic film in a polystyrene phantom by turning off the magnetic scanning system. The mean deviation calculated from measured dose distributions is about 0.2%; a few points have deviations as large as 2 to 4% inside of the 50% isodose curve, but less than 8% outside of the 50% isodose curve. The model has been used to generate the electron beam library required by a modified version of a commercially-available computerized treatment-planning system. (The RAD-8 treatment planning system was purchased from the Digital Equipment Corporation. It is currently available from Electronic Music Industries (EMI), Ltd.)

  6. A Correlative Optical Microscopy and Scanning Electron Microscopy Approach to Locating Nanoparticles in Brain Tumors

    PubMed Central

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

    2014-01-01

    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. PMID:25464144

  7. 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.

  8. Evolution of MEMS scanning mirrors for laser projection in compact consumer electronics

    NASA Astrophysics Data System (ADS)

    Tauscher, Jason; Davis, Wyatt O.; Brown, Dean; Ellis, Matt; Ma, Yunfei; Sherwood, Michael E.; Bowman, David; Helsel, Mark P.; Lee, Sung; Coy, John Wyatt

    2010-02-01

    The applicability of MOEMS scanning mirrors towards the creation of "flying spot" scanned laser displays is well established. The extension of this concept towards compact embedded pico-projectors has required an evolution of scanners and packaging to accommodate the needs of the consumer electronics space. This paper describes the progression of the biaxial MOEMS scanning mirrors developed by Microvision over recent years. Various aspects of the individual designs are compared. Early devices used a combination of magnetic quasistatic actuation and resonant electrostatic operation in an evacuated atmosphere to create a projection engine for retinal scanned displays. Subsequent designs realized the elimination of both the high voltage electrostatic drive and the vacuum package, and a simplification of the actuation scheme through proprietary technical advances. Additional advances have doubled the scan angle capability and greatly miniaturized the MOEMS component while not incurring significant increase in power consumption, making it an excellent fit for the consumer pico-projector application. The simplicity of the scanned laser-based pico-projector optical design enables high resolution and a large effective image size in a thin projection engine, all of which become critical both to the viability of the technology and adoption by consumers. Microvision's first scanned laser pico-projector is built around a MOEMS scanning mirror capable of projecting 16:9 aspect ratio, WVGA display within a 6.6 mm high package. Further evolution on this path promises continued improvement in resolution, size, and power.

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2013-10-01

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

  11. Probing cytotoxicity of nanoparticles and organic compounds using scanning proton microscopy, scanning electron microscopy and fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Tong, Yongpeng; Li, Changming; Liang, Feng; Chen, Jianmin; Zhang, Hong; Liu, Guoqing; Sun, Huibin; Luong, John H. T.

    2008-12-01

    Scanning proton microscopy, scanning electron microscopy (SEM) and fluorescence microscopy have been used to probe the cytotoxicity effect of benzo[a]pyrene (BaP), ethidium bromide (EB) and nanoparticles (ZnO, Al 2O 3 and TiO 2) on a T lymphoblastic leukemia Jurkat cell line. The increased calcium ion (from CaCl 2) in the culture medium stimulated the accumulation of BaP and EB inside the cell, leading to cell death. ZnO, Al 2O 3 and TiO 2 nanoparticles, however, showed a protective effect against these two organic compounds. Such inorganic nanoparticles complexed with BaP or EB which became less toxic to the cell. Fe 2O 3 nanoparticles as an insoluble particle model scavenged by macrophage were investigated in rats. They were scavenged out of the lung tissue about 48 h after infection. This result suggest that some insoluble inorganic nanoparticles of PM (particulate matters) showed protective effects on organic toxins induced acute toxic effects as they can be scavenged by macrophage cells. Whereas, some inorganic ions such as calcium ion in PM may help environmental organic toxins to penetrate cell membrane and induce higher toxic effect.

  12. Three-dimensional location of a single dopant with atomic precision by aberration-corrected scanning transmission electron microscopy.

    PubMed

    Ishikawa, Ryo; Lupini, Andrew R; Findlay, Scott D; Taniguchi, Takashi; Pennycook, Stephen J

    2014-01-01

    Materials properties, such as optical and electronic response, can be greatly enhanced by isolated single dopants. Determining the full three-dimensional single-dopant defect structure and spatial distribution is therefore critical to understanding and adequately tuning functional properties. Combining quantitative Z-contrast scanning transmission electron microscopy images with image simulations, we show the direct determination of the atomic-scale depth location of an optically active, single atom Ce dopant embedded within wurtzite-type AlN. The method represents a powerful new tool for reconstructing three-dimensional information from a single, two-dimensional image.

  13. Study on the parameters of the scanning system for the 300 keV electron accelerator

    SciTech Connect

    Leo, K. W.; Chulan, R. M. Hashim, S. A.; Baijan, A. H.; Sabri, R. M.; Mohtar, M.; Glam, H.; Lojius, L.; Zahidee, M.; Azman, A.; Zaid, M.

    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 of 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.

  14. Scanning precession electron tomography for three-dimensional nanoscale orientation imaging and crystallographic analysis

    PubMed Central

    Eggeman, Alexander S.; Krakow, Robert; Midgley, Paul A.

    2015-01-01

    Three-dimensional (3D) reconstructions from electron tomography provide important morphological, compositional, optical and electro-magnetic information across a wide range of materials and devices. Precession electron diffraction, in combination with scanning transmission electron microscopy, can be used to elucidate the local orientation of crystalline materials. Here we show, using the example of a Ni-base superalloy, that combining these techniques and extending them to three dimensions, to produce scanning precession electron tomography, enables the 3D orientation of nanoscale sub-volumes to be determined and provides a one-to-one correspondence between 3D real space and 3D reciprocal space for almost any polycrystalline or multi-phase material. PMID:26028514

  15. Probing core-electron orbitals by scanning transmission electron microscopy and measuring the delocalization of core-level excitations

    NASA Astrophysics Data System (ADS)

    Jeong, Jong Seok; Odlyzko, Michael L.; Xu, Peng; Jalan, Bharat; Mkhoyan, K. Andre

    2016-04-01

    By recording low-noise energy-dispersive x-ray spectroscopy maps from crystalline specimens using aberration-corrected scanning transmission electron microscopy, it is possible to probe core-level electron orbitals in real space. Both the 1 s and 2 p orbitals of Sr and Ti atoms in SrTi O3 are probed, and their projected excitation potentials are determined. This paper also demonstrates experimental measurement of the electronic excitation impact parameter and the delocalization of an excitation due to Coulombic beam-orbital interaction.

  16. The scanning electron microscope in microbiology and diagnosis of infectious disease

    PubMed Central

    Golding, Christine G.; Lamboo, Lindsey L.; Beniac, Daniel R.; Booth, Timothy F.

    2016-01-01

    Despite being an excellent tool for investigating ultrastructure, scanning electron microscopy (SEM) is less frequently used than transmission electron microscopy for microbes such as viruses or bacteria. Here we describe rapid methods that allow SEM imaging of fully hydrated, unfixed microbes without using conventional sample preparation methods. We demonstrate improved ultrastructural preservation, with greatly reduced dehydration and shrinkage, for specimens including bacteria and viruses such as Ebola virus using infiltration with ionic liquid on conducting filter substrates for SEM. PMID:27212232

  17. Tip surface changes in endocardial stimulation electrode, visualised by scanning electron microscopy.

    PubMed

    Hladky, M; Horn, V; Kamaryt, P; Cabanova, J; Zeman, K

    1975-01-01

    The authors have been probably the first investigators who applied scanning electron microscopy to studies of the changes occurring in the surface of the metalic tip of an endocardial stimulating electrode. They found a lowered conductivity for secondary electron emission, and describe the surface changes in a platiniridium-tipped electrode which had been used for almost four years, in comparison with an unused electrode.

  18. Modeling for accurate dimensional scanning electron microscope metrology: then and now.

    PubMed

    Postek, Michael T; Vladár, András E

    2011-01-01

    A review of the evolution of modeling for accurate dimensional scanning electron microscopy is presented with an emphasis on developments in the Monte Carlo technique for modeling the generation of the electrons used for imaging and measurement. The progress of modeling for accurate metrology is discussed through a schematic technology timeline. In addition, a discussion of a future vision for accurate SEM dimensional metrology and the requirements to achieve it are presented.

  19. Phase reconstruction in annular bright-field scanning transmission electron microscopy.

    PubMed

    Ishida, Takafumi; Kawasaki, Tadahiro; Tanji, Takayoshi; Kodama, Tetsuji; Matsutani, Takaomi; Ogai, Keiko; Ikuta, Takashi

    2015-04-01

    A novel technique for reconstructing the phase shifts of electron waves was applied to Cs-corrected scanning transmission electron microscopy (STEM). To realize this method, a new STEM system equipped with an annular aperture, annularly arrayed detectors and an arrayed image processor has been developed and evaluated in experiments. We show a reconstructed phase image of graphite particles and demonstrate that this new method works effectively for high-resolution phase imaging.

  20. Energy dispersive X-ray analysis on an absolute scale in scanning transmission electron microscopy.

    PubMed

    Chen, Z; D'Alfonso, A J; Weyland, M; Taplin, D J; Allen, L J; Findlay, S D

    2015-10-01

    We demonstrate absolute scale agreement between the number of X-ray counts in energy dispersive X-ray spectroscopy using an atomic-scale coherent electron probe and first-principles simulations. Scan-averaged spectra were collected across a range of thicknesses with precisely determined and controlled microscope parameters. Ionization cross-sections were calculated using the quantum excitation of phonons model, incorporating dynamical (multiple) electron scattering, which is seen to be important even for very thin specimens.

  1. 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.

  2. 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.

  3. Dental wax impressions of plant tissues for viewing with scanning electron microscopy (SEM).

    PubMed

    Beermann, Anke; Hülskamp, Martin

    2010-09-01

    Scanning electron microscopy (SEM) is a valuable method for examining surface structures. Taking wax impressions of plant structures, such as leaves, is a nondestructive procedure that makes it possible to view changes in surface structures over time, such as during development. This protocol describes a method for making dental wax impressions of plant tissues.

  4. Electronic properties of graphene: a perspective from scanning tunneling microscopy and magnetotransport.

    PubMed

    Andrei, Eva Y; Li, Guohong; Du, Xu

    2012-05-01

    This review covers recent experimental progress in probing the electronic properties of graphene and how they are influenced by various substrates, by the presence of a magnetic field and by the proximity to a superconductor. The focus is on results obtained using scanning tunneling microscopy, spectroscopy, transport and magnetotransport techniques.

  5. 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.

  6. 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...

  7. 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...

  8. Scanning electron microscopic study of an anterior chamber intraocular lens: latent endophthalmitis.

    PubMed

    Schémann, J F

    1987-01-01

    Two years after intracapsular cataract extraction and intraocular lens implantation, an anterior chamber lens was removed. The lens was studied by scanning electron microscope which demonstrated the presence of colonies of cocci, a thin acellular membrane covering part of the lens and some modifications of the lens surface.

  9. The Sensura Neglecta in the Pigeon: A Scanning Electron and Light Microscope Study.

    DTIC Science & Technology

    Both scanning electron and light microscopy have been used to observe the tiny sensura neglecta which is located in the inferior utricula sinus of...the vestibular labyrinth in the pigeon. Observations indicate that the sensura neglecta in the pigeon has both crista- and macula-like features. It is

  10. Light and scanning electron microscopic and immunohistochemical studies on permeability of hypertensive rat mesenteric arteries.

    PubMed

    Suzuki, K; Kawaharada, U; Takatama, M; Ooneda, G

    1985-09-01

    Experimental hypertensive rats were intravenously injected with carbon and iron as tracers, and their mesenteric arteries exhibiting hypertensive arterial lesions were observed by light and scanning electron microscopy and immunohistochemistry. Early arterial lesions showing intense medial damages, deposition of fibrinoid substance consisting of fibrin in the intima and/or media, and granulation tissue in the adventitia were characterized by marked insudation of intravenously injected tracers. Scanning electron microscopy demonstrated numerous leukocytes and platelets adhering to endothelial surface, opened endothelial cell junctions, and desquamation of these cells. Immunohistochemistry revealed laminin and low stainability of fibronectin in the subendothelium. Advanced lesions showed deposition of a large amount of fibrinoid substance and no insudation of tracers in the intima, but scanning electron microscopy manifested opening of endothelial cell junctions, desquamation of endothelial cells, and adherence of leukocytes and platelets. Immunohistochemistry revealed fibronectin in the intima and laminin just beneath the endothelium. In the healed lesions disclosing fibrocellular intimal thickening, there was no insudation of tracers. Scanning electron microscopy showed opened endothelial cell junctions, endothelial cell defects, and adherence of leukocytes and platelets. There were fibronectin in the intima and laminin beneath the endothelium. It was suggested that the opening of endothelial cells junctions and desquamation of endothelial cells would be necessary for the arterial increased permeability in hypertensive rats, and that fibrin-fibronectin complex, fibronectin-acid mucopolysaccharide complex, and basement membrane would together inhibit the increased permeability in the mesenteric arteries of hypertensive rats in spite of endothelial cell injuries and their defects.

  11. 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.

  12. Three-dimensional bright-field scanning transmission electron microscopy elucidate novel nanostructure in microbial biofilms.

    PubMed

    Hickey, William J; Shetty, Ameesha R; Massey, Randall J; Toso, Daniel B; Austin, Jotham

    2017-01-01

    Bacterial biofilms play key roles in environmental and biomedical processes, and understanding their activities requires comprehension of their nanoarchitectural characteristics. Electron microscopy (EM) is an essential tool for nanostructural analysis, but conventional EM methods are limited in that they either provide topographical information alone, or are suitable for imaging only relatively thin (<300 nm) sample volumes. For biofilm investigations, these are significant restrictions. Understanding structural relations between cells requires imaging of a sample volume sufficiently large to encompass multiple cells and the capture of both external and internal details of cell structure. An emerging EM technique with such capabilities is bright-field scanning transmission electron microscopy (BF-STEM) and in the present report BF-STEM was coupled with tomography to elucidate nanostructure in biofilms formed by the polycyclic aromatic hydrocarbon-degrading soil bacterium, Delftia acidovorans Cs1-4. Dual-axis BF-STEM enabled high-resolution 3-D tomographic recontructions (6-10 nm) visualization of thick (1250 and 1500 nm) sections. The 3-D data revealed that novel extracellular structures, termed nanopods, were polymorphic and formed complex networks within cell clusters. BF-STEM tomography enabled visualization of conduits formed by nanopods that could enable intercellular movement of outer membrane vesicles, and thereby enable direct communication between cells. This report is the first to document application of dual-axis BF-STEM tomography to obtain high-resolution 3-D images of novel nanostructures in bacterial biofilms. Future work with dual-axis BF-STEM tomography combined with correlative light electron microscopy may provide deeper insights into physiological functions associated with nanopods as well as other nanostructures.

  13. Neutrophils scan for activated platelets to initiate inflammation

    PubMed Central

    Sreeramkumar, Vinatha; Adrover, José M.; Ballesteros, Ivan; Cuartero, Maria Isabel; Rossaint, Jan; Bilbao, Izaskun; Nácher, Maria; Pitaval, Christophe; Radovanovic, Irena; Fukui, Yoshinori; McEver, Rodger P.; Filippi, Marie-Dominique; Lizasoain, Ignacio; Ruiz-Cabello, Jesús; Zarbock, Alexander; Moro, María A.; Hidalgo, Andrés

    2014-01-01

    Immune and inflammatory responses require leukocytes to migrate within and through the vasculature, a process that is facilitated by their capacity to switch to a polarized morphology with asymmetric distribution of receptors. We report that neutrophil polarization within activated venules served to organize a protruding domain that engaged activated platelets present in the bloodstream. The selectin ligand PSGL-1 transduced signals emanating from these interactions, resulting in redistribution of receptors that drive neutrophil migration. Consequently, neutrophils unable to polarize or to transduce signals through PSGL-1 displayed aberrant crawling, and blockade of this domain protected mice against thrombo-inflammatory injury. These results reveal that recruited neutrophils scan for activated platelets, and suggest that their bipolarity allows integration of signals present at both the endothelium and the circulation before inflammation proceeds. PMID:25477463

  14. Minimum Detectable Activity for Tomographic Gamma Scanning System

    SciTech Connect

    Venkataraman, Ram; Smith, Susan; Kirkpatrick, J. M.; Croft, Stephen

    2015-01-01

    For any radiation measurement system, it is useful to explore and establish the detection limits and a minimum detectable activity (MDA) for the radionuclides of interest, even if the system is to be used at far higher values. The MDA serves as an important figure of merit, and often a system is optimized and configured so that it can meet the MDA requirements of a measurement campaign. The non-destructive assay (NDA) systems based on gamma ray analysis are no exception and well established conventions, such the Currie method, exist for estimating the detection limits and the MDA. However, the Tomographic Gamma Scanning (TGS) technique poses some challenges for the estimation of detection limits and MDAs. The TGS combines high resolution gamma ray spectrometry (HRGS) with low spatial resolution image reconstruction techniques. In non-imaging gamma ray based NDA techniques measured counts in a full energy peak can be used to estimate the activity of a radionuclide, independently of other counting trials. However, in the case of the TGS each “view” is a full spectral grab (each a counting trial), and each scan consists of 150 spectral grabs in the transmission and emission scans per vertical layer of the item. The set of views in a complete scan are then used to solve for the radionuclide activities on a voxel by voxel basis, over 16 layers of a 10x10 voxel grid. Thus, the raw count data are not independent trials any more, but rather constitute input to a matrix solution for the emission image values at the various locations inside the item volume used in the reconstruction. So, the validity of the methods used to estimate MDA for an imaging technique such as TGS warrant a close scrutiny, because the pair-counting concept of Currie is not directly applicable. One can also raise questions as to whether the TGS, along with other image reconstruction techniques which heavily intertwine data, is a suitable method if one expects to measure samples whose activities

  15. Relationships between uterus and eggs in cestodes from different taxa, as revealed by scanning electron microscopy.

    PubMed

    Korneva, Janetta V; Kornienko, Svetlana A; Kuklin, Vadim V; Pronin, Nikolay M; Jones, Malcolm K

    2014-01-01

    Uterine organization and interaction with developing eggs in Tetrabothrius erostris (Tetrabothriidea), Nippotaenia mogurndae (Nippotaeniidea), Arostrilepis tenuicirrosa, and Monocercus arionis (Cyclophyllidea), cestodes belonging to three different orders, were investigated by scanning electron microscopy. The interactions were traced from sexually mature to gravid proglottids for all species. Pieces of evidence of interactions among these species include specific tight contacts between microlamellae of the uterine epithelium and the egg capsule, networks of fibrils between eggs and uterus, or numerous branched diverticula of the uterine wall that surround eggs or combinations of these. The contacts between uterine epithelium and eggs take place in mature and post-mature proglottids, at a period of development when eggs are newly formed and the embryos are rapidly developing. The eggs grow and develop actively in tight contact with the uterine wall. The maximum diameter of eggs increases 1.5-2 times (or 3.5-4 times in M. arionis) during development. In all species, the intimate contacts between uterus and eggs have weakened or disappeared by the time the proglottids have become gravid. The association between uterus and eggs thus appears as strong evidence of active trophic interaction (or matrotrophy) between the parent organism and developing eggs.

  16. Focus Ion Beam/Scanning Electron Microscopy Characterization of Osteoclastic Resorption of Calcium Phosphate Substrates.

    PubMed

    Diez-Escudero, Anna; Espanol, Montserrat; Montufar, Edgar B; Di Pompo, Gemma; Ciapetti, Gabriela; Baldini, Nicola; Ginebra, Maria-Pau

    2017-02-01

    This article presents the application of dual focused ion beam/scanning electron microscopy (FIB-SEM) imaging for preclinical testing of calcium phosphates with osteoclast precursor cells and how this high-resolution imaging technique is able to reveal microstructural changes at a level of detail previously not possible. Calcium phosphate substrates, having similar compositions but different microstructures, were produced using low- and high-temperature processes (biomimetic calcium-deficient hydroxyapatite [CDHA] and stoichiometric sintered hydroxyapatite, respectively). Human osteoclast precursor cells were cultured for 21 days before evaluating their resorptive potential on varying microstructural features. Alternative to classical morphological evaluation of osteoclasts (OC), FIB-SEM was used to observe the subjacent microstructure by transversally sectioning cells and observing both the cells and the substrates. Resorption pits, indicating OC activity, were visible on the smoother surface of high-temperature sintered hydroxyapatite. FIB-SEM analysis revealed signs of acidic degradation on the grain surface under the cells, as well as intergranular dissolution. No resorption pits were evident on the surface of the rough CDHA substrates. However, whereas no degradation was detected by FIB sections in the material underlying some of the cells, early stages of OC-mediated acidic degradation were observed under cells with more spread morphology. Collectively, these results highlight the potential of FIB to evaluate the resorptive activity of OC, even in rough, irregular, or coarse surfaces where degradation pits are otherwise difficult to visualize.

  17. Enhanced contrast separation in scanning electron microscopes via a suspended-thin sample approach.

    PubMed

    Ji, Yuan; Wang, Li; Guo, Zhenxi; Wei, Bin; Zhao, Jie; Wang, Xiaodong; Zhang, Yinqi; Sui, Manling; Han, Xiaodong

    2014-11-01

    A suspended-thin-sample (STS) approach for signal selection and contrast separation is developed in scanning electron microscopes with commonly used primary beam energies and traditional detectors. Topography contrast, electron channeling contrast and composition contrast are separated and largely enhanced from suspended thin samples of several hundred nanometers in thickness, which is less than the escape depth of backscattered electrons. This imaging technique enables to detect relatively pure secondary electron and elastic backscattered electron singles, whereas suppress multiple inelastic scattering effects. The provided contrast features are different from those of bulk samples, which are largely mixed with inelastic scattering effects. The STS imaging concept and method could be expected to have more applications in distinguishing materials of nanostructures, multilayers, compounds and composites, as well as in SEM-based electron backscatter diffraction, cathodoluminesence, and x-ray microanalysis.

  18. [Depth dose characteristics of electron beams released from a scanning type Racetrack Microtron treatment machine].

    PubMed

    Sato, Tomoharu

    2002-01-01

    The Racetrack Microtron MM50 capable of taking out x-rays and electron beams having a high energy of up to 50 MeV was evaluated by a dosimetry of electron beams in comparison with Microtron MM22. The MM50 flattens the intensity of electron beams by using the beam scanning method while the MM22 utilizes the flattening-filter method. A percentage depth dose (PDD) curve was obtained through the dosimetry of electron beams using a water phantom. As compared with the MM22, the MM50 emits an electron beam that has an energy much closer to the nominal one, that is less contaminated by x-rays, and whose intensity decreases steeply down to near zero on the PDD curve. The MM50 has an electron beam dose distribution that is practically useful since the dose tends to be concentrated on the target volume.

  19. Telocytes and putative stem cells in the lungs: electron microscopy, electron tomography and laser scanning microscopy.

    PubMed

    Popescu, Laurentiu M; Gherghiceanu, Mihaela; Suciu, Laura C; Manole, Catalin G; Hinescu, Mihail E

    2011-09-01

    This study describes a novel type of interstitial (stromal) cell - telocytes (TCs) - in the human and mouse respiratory tree (terminal and respiratory bronchioles, as well as alveolar ducts). TCs have recently been described in pleura, epicardium, myocardium, endocardium, intestine, uterus, pancreas, mammary gland, etc. (see www.telocytes.com ). TCs are cells with specific prolongations called telopodes (Tp), frequently two to three per cell. Tp are very long prolongations (tens up to hundreds of μm) built of alternating thin segments known as podomers (≤ 200 nm, below the resolving power of light microscope) and dilated segments called podoms, which accommodate mitochondria, rough endoplasmic reticulum and caveolae. Tp ramify dichotomously, making a 3-dimensional network with complex homo- and heterocellular junctions. Confocal microscopy reveals that TCs are c-kit- and CD34-positive. Tp release shed vesicles or exosomes, sending macromolecular signals to neighboring cells and eventually modifying their transcriptional activity. At bronchoalveolar junctions, TCs have been observed in close association with putative stem cells (SCs) in the subepithelial stroma. SCs are recognized by their ultrastructure and Sca-1 positivity. Tp surround SCs, forming complex TC-SC niches (TC-SCNs). Electron tomography allows the identification of bridging nanostructures, which connect Tp with SCs. In conclusion, this study shows the presence of TCs in lungs and identifies a TC-SC tandem in subepithelial niches of the bronchiolar tree. In TC-SCNs, the synergy of TCs and SCs may be based on nanocontacts and shed vesicles.

  20. 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.

  1. Charged nanoparticle dynamics in water induced by scanning transmission electron microscopy.

    PubMed

    White, E R; Mecklenburg, Matthew; Shevitski, Brian; Singer, S B; Regan, B C

    2012-02-28

    Using scanning transmission electron microscopy we image ~4 nm platinum nanoparticles deposited on an insulating membrane, where the membrane is one of two electron-transparent windows separating an aqueous environment from the microscope's high vacuum. Upon receiving a relatively moderate dose of ~10(4) e/nm(2), initially immobile nanoparticles begin to move along trajectories that are directed radially outward from the center of the field of view. With larger dose rates the particle motion becomes increasingly dramatic. These observations demonstrate that, even under mild imaging conditions, the in situ electron microscopy of aqueous environments can produce electrophoretic charging effects that dominate the dynamics of nanoparticles under observation.

  2. SEM, TEM and SLEEM (scanning low energy electron microscopy) of CB2 steel after creep testing

    NASA Astrophysics Data System (ADS)

    Kasl, J.; Mikmeková, Š.; Jandová, D.

    2014-03-01

    The demand to produce electrical power with higher efficiency and with lower environmental pollution is leading to the use of new advanced materials in the production of power plant equipment. To understand the processes taking place in parts produced from these materials during their operation under severe conditions (such as high temperature, high stress, and environmental corrosion) requires detailed evaluation of their substructure. It is usually necessary to use transmission electron microscopy (TEM). However, this method is very exacting and time-consuming. So there is an effort to use new scanning electron microscopy techniques instead of TEM. One of them is scanning low energy electron microscopy (SLEEM). This paper deals with an assessment of the possibility to use SLEEM for describing the substructure of creep resistant steel CB2 after long-term creep testing. In the SLEEM images more information is contained about the microstructure of the material in comparison with standard scanning electron microscopy. Study of materials using slow and very slow electrons opens the way to better understanding their microstructures.

  3. 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.

  4. The Scanning Theremin Microscope: A Model Scanning Probe Instrument for Hands-On Activities

    ERIC Educational Resources Information Center

    Quardokus, Rebecca C.; Wasio, Natalie A.; Kandel, S. Alex

    2014-01-01

    A model scanning probe microscope, designed using similar principles of operation to research instruments, is described. Proximity sensing is done using a capacitance probe, and a mechanical linkage is used to scan this probe across surfaces. The signal is transduced as an audio tone using a heterodyne detection circuit analogous to that used in…

  5. Local imaging of high mobility two-dimensional electron systems with virtual scanning tunneling microscopy

    SciTech Connect

    Pelliccione, M.; Bartel, J.; Goldhaber-Gordon, D.; Sciambi, A.; Pfeiffer, L. N.; West, K. W.

    2014-11-03

    Correlated electron states in high mobility two-dimensional electron systems (2DESs), including charge density waves and microemulsion phases intermediate between a Fermi liquid and Wigner crystal, are predicted to exhibit complex local charge order. Existing experimental studies, however, have mainly probed these systems at micron to millimeter scales rather than directly mapping spatial organization. Scanning probes should be well-suited to study the spatial structure of these states, but high mobility 2DESs are found at buried semiconductor interfaces, beyond the reach of conventional scanning tunneling microscopy. Scanning techniques based on electrostatic coupling to the 2DES deliver important insights, but generally with resolution limited by the depth of the 2DES. In this letter, we present our progress in developing a technique called “virtual scanning tunneling microscopy” that allows local tunneling into a high mobility 2DES. Using a specially designed bilayer GaAs/AlGaAs heterostructure where the tunnel coupling between two separate 2DESs is tunable via electrostatic gating, combined with a scanning gate, we show that the local tunneling can be controlled with sub-250 nm resolution.

  6. 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.

  7. An electro-conductive organic coating for scanning electron microscopy (déjà vu)

    NASA Astrophysics Data System (ADS)

    Burnett, Bryan R.

    2014-09-01

    An organic compound, originally marketed as an antistatic, can form an extremely thin electro-conductive coating upon drying. A scanning electron microscope (SEM) application for this compound was first explored in the late 1960s. A coating of this compound eliminates the need for carbon or gold coating in some applications. It is well suited for the viewing of fabric samples and associated gunshot residue (GSR) in the SEM and makes it possible to quickly analyze fabric bullet wipe and bore wipe GSR. Fabric samples can also be examined for GSR from intermediate-range shots to estimate muzzle-target distances. Scanning

  8. Fabrication and characterization of solid-state nanopores using a field emission scanning electron microscope

    SciTech Connect

    Chang Hung; Iqbal, Samir M.; Stach, Eric A.; King, Alexander H.; Zaluzec, Nestor J.; Bashir, Rashid

    2006-03-06

    The fabrication of solid-state nanopores using the electron beam of a transmission electron microscope (TEM) has been reported in the past. Here, we report a similar method to fabricate solid-state nanopores using the electron source of a conventional field-emission scanning electron microscope (FESEM) instead. Micromachining was used to create initial pore diameters between 50 nm and 200 nm, and controlled pore shrinking to sub 10 nm diameters was performed subsequently during in situ processing in the FESEM. Noticeably, different shrinking behavior was observed when using irradiation from the electron source of the FESEM than the TEM. Unlike previous reports of TEM mediated pore shrinkage, the mechanism of pore shrinkage when using the FESEM could be a result of surface defects generated by radiolysis and subsequent motion of silicon atoms to the pore periphery.

  9. Image formation mechanisms in scanning electron microscopy of carbon nanotubes, and retrieval of their intrinsic dimensions.

    PubMed

    Jackman, H; Krakhmalev, P; Svensson, K

    2013-01-01

    We present a detailed analysis of the image formation mechanisms that are involved in the imaging of carbon nanotubes with scanning electron microscopy (SEM). We show how SEM images can be modelled by accounting for surface enhancement effects together with the absorption coefficient for secondary electrons, and the electron-probe shape. Images can then be deconvoluted, enabling retrieval of the intrinsic nanotube dimensions. Accurate estimates of their dimensions can thereby be obtained even for structures that are comparable to the electron-probe size (on the order of 2 nm). We also present a simple and robust model for obtaining the outer diameter of nanotubes without any detailed knowledge about the electron-probe shape.

  10. 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.

  11. Scanning electron microscopy of the nail plate in onychomycosis patients with negative fungal culture.

    PubMed

    Yue, Xueping; Li, Qing; Wang, Hongwei; Sun, Yilin; Wang, Aiping; Zhang, Qi; Zhang, Cuiping

    2016-01-01

    Onychomycosis is a common dermatological problem and can be identified by direct microscopic examination and fungal culture. However, the positive rate of fungal culture is low. This study investigated the application of scanning electron microscopy in the diagnosis of onychomycosis in 20 patients with negative fungal culture. In this study, a routine glutaraldehyde fixation method was used to prepare specimens for electron microscope examination. Results showed that under the scanning electron microscope, significant structural damage was observed in the nail plate in all patients. Hyphaes were seen in 70% of cases. A mixture of scattered hyphaes, pseudohyphaes, and spores was observed in 30% of cases. A mixture of spores and bacteria was observed in 10% of cases. A mixture of hyphaes and bacteria was observed in 20% of cases. The typical hyphae pierced a thin layer or single layer of corneocytes. Hyphaes could be smooth, sleek, and straight with visible separation, or dry, bent, and folded with a smooth surface. The diameter of hyphaes was 1-2 µm. The scattered spores were the main form of spore growth, and the growth of budding spores can be seen attached to the surface of layered armor. Most of the bacteria were gathered in clumps on the ventral surface, especially in grooves. In conclusion, scanning electron microscopy can be used to preliminarily identify the pathogen involved and the degree of damage in cases where onychomycosis is clinically diagnosed, but fungal culture is negative.

  12. Thromboembolic ischemic stroke and the presence of necrotic platelets: a scanning electron microscopy investigation.

    PubMed

    Pretorius, Etheresia; Engelbrecht, Mia-Jeanne; Duim, Wiebren

    2012-02-01

    Stroke is one of the most debilitating diseases worldwide, with its occurrence increasing in Western societies. Central to the pathogenesis of thromboembolic stroke is the involvement of platelets. During thromboembolic events, nucleated cells undergo cell death, and platelets are also affected by parameters causing these incidents. Particularly, initiation of necrotic cell death at sites of vascular injury may play an important role in inducing inflammatory and repair processes. In the current research, the authors investigate whether a changed platelet ultrastructure is visible in thromboembolic stroke and whether it might be visible in platelets as apoptosis or necrosis. Therefore, in the current investigation, the authors study smears of platelet-rich plasma (PRP) from thromboembolic ischemic stroke patients to investigate whether a changed morphology is visible in distressed platelets. Scanning electron microscopy is used and platelets are viewed at up to 200,000× machine magnification. Results indicate that thromboembolic ischemic stroke causes membrane tears and swollen platelets, and this is indicative of necrosis. It is therefore concluded that this morphology might be due to the pro-coagulant activity characteristic of the disease.

  13. Comparison of staining techniques for scanning electron microscopic detection of ultrastructural protuberances on cellulolytic bacteria.

    PubMed

    Blair, B G; Anderson, K L

    1998-03-01

    Cell surface protuberances found on cellulolytic bacteria, but not on noncellulolytic bacteria, can be detected by scanning electron microscopy. Cationized ferritin typically has been used as a stain to increase the microscopic resolution of these protuberances; however, as a cation it binds only to negatively charged molecules. Thus, binding of cationized ferritin to cell surface molecules can be affected by the cell's physiological state. We incubated the noncellulolytic bacterium, Clostridium beijerinckii, in different media at various temperatures to obtain cells with different growth rates and physiological states. Staining of these cells with cationized ferritin showed that slower growing cells exhibited more protuberant structures than faster growing cells. This provided a clear correlation of ultrastructural protuberances with physiological changes associated with growth rate. On the other hand, cells stained with osmium tetroxide exhibited no protuberant structures regardless of growth rate. Because various cations are known to induce aggregation of surface proteins on some cellulolytic Clostridia, we incubated the cellulolytic bacterium, Clostridium cellulovorans, in media containing glucose, cellobiose, or cellulose. Ultrastructural protuberances were evident on all cells stained with cationized ferritin, but extensive protuberances were detected only on cells grown in cellulose and stained with osmium tetroxide. For cells stained with cationized ferritin, the presence of ultrastructural protuberances was correlated with growth rate rather than induction of cellulolytic systems. By contrast, cells stained with osmium tetroxide showed a clear correlation between protuberant structures and cellulolytic activity.

  14. Scanning electron microscopic study of human neuroblastoma cells affected with Naegleria fowleri Thai strains.

    PubMed

    Tiewcharoen, Supathra; Rabablert, Jundee; Chetanachan, Pruksawan; Junnu, Virach; Worawirounwong, Dusit; Malainual, Nat

    2008-10-01

    In order to understand the pathogenesis of Naegleria fowleri in primary amoebic meningoencephalitis, the human neuroblastoma (SK-N-MC) and African green monkey kidney (Vero) cells were studied in vitro. Amoeba suspension in cell-culture medium was added to the confluent monolayer of SK-N-MC and Vero cells. The cytopathic activity of N. fowleri trophozoites in co-culture system was elucidated by scanning electron microscope at 3, 6, 9, 12, and 24 h. Two strains of N. fowleri displayed well-organized vigorous pseudopods in Nelson's medium at 37 degrees C. In co-culture, the target monolayer cells were damaged by two mechanisms, phagocytosis by vigorous pseudopods and engulfment by sucker-like apparatus. N. fowleri trophozoites produced amoebostomes only in co-culture with SK-N-MC cells. In contrast, we could not find such apparatus in the co-culture with Vero cells. The complete destruction time (100%) at 1:1 amoeba/cells ratio of SK-N-MC cells (1 day) was shorter than the Vero cells (12 days). In conclusion, SK-N-MC cells were confirmed to be a target model for studying neuropathogenesis of primary amoebic meningoencephalitis.

  15. Vasculature of the ophthalmic rete in night herons (Nycticorax nycticorax): scanning electron microscopy of corrosion casts.

    PubMed

    Ninomiya, Hiroyoshi

    2002-09-01

    Vasculature of the ophthalmic rete (rete ophthalmicum) in the night heron (Nycticorax nycticorax) was studied using scanning electron microscopy of vascular corrosion casts and light microscopy on tissue sections. Most blood to the eyeball and a lesser volume of blood to the brain passed through the ophthalmic rete via the external ophthalmic artery. The collateral retial arterioles originated from the external ophthalmic artery forming a flat and fusiform-shaped arterial network at the ventrotemporal region of the eyeball. The arterial network was intermixed with a similar complex of the veins from the eye. The ophthalmotemporal artery, which supplied the eyeball posteriorly, and supraorbital and infraorbital arteries, which supplied the eyeball anteriorly, originated from the rete. Blood from the eye, which is a site of potential heat loss, drained into the ophthalmic rete via the ophthalmotemporal vein. On the casts of retial arterioles, slit-like cleavages at branching sites representing flap valves, which might play a role as sluice valves, were seen. In addition, marks of circularly running grooves, which might represent tufts of smooth muscle cells and might contribute to a sphincter activity, were observed. These anatomical specializations of the avian ophthalmic rete, involving parallel arrangement of arteries and veins, may function to facilitate counter-current heat exchange and to regulate blood pressure and volume to the eye and the brain.

  16. 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.

  17. Scanning electron microscopy observations of the interaction between Trichoderma harzianum and perithecia of Gibberella zeae.

    PubMed

    Inch, S; Gilbert, J

    2011-01-01

    Chronological events associated with the interaction between a strain of Trichoderma harzianum, T472, with known biological control activity against perithecial production of G. zeae, were studied with scanning electron microscopy to investigate the mechanisms of control. Large clusters of perithecia consisting of 5-15 perithecia formed on the autoclaved, mulched wheat straw inoculated with G. zeae alone (control) with an average of 157 perithecia per plate. Small clusters consisting of 3-6 and an average of 15 perithecia per plate perithecia formed on straw that was treated with T. harzianum. The mature perithecia from straw treated with T. harzianum produced less pigment and were lighter in color than those from the control plates. Furthermore the cells of the outer wall of these perithecia were abnormal in appearance and unevenly distributed across the surface. Immature perithecia were colonized by T. harzianum approximately 15 d after inoculation (dai) with the biocontrol agent and pathogen. Few perithecia were colonized at later stages. The affected perithecia collapsed 21 dai, compared to the perithecia in the control samples that began to collapse 28 dai. Abundant mycelium of T. harzianum was seen on the perithecia of treated samples. Perithecial structures may be resistant to penetration by the mycelium because direct penetration was not observed. Trichoderma harzianum colonized the substrate quickly and out-competed the pathogen, G. zeae.

  18. Scanning Electron Microscope Calibration Using a Multi-Image Non-Linear Minimization Process

    NASA Astrophysics Data System (ADS)

    Cui, Le; Marchand, Éric

    2015-04-01

    A scanning electron microscope (SEM) calibrating approach based on non-linear minimization procedure is presented in this article. A part of this article has been published in IEEE International Conference on Robotics and Automation (ICRA), 2014. . Both the intrinsic parameters and the extrinsic parameters estimations are achieved simultaneously by minimizing the registration error. The proposed approach considers multi-images of a multi-scale calibration pattern view from different positions and orientations. Since the projection geometry of the scanning electron microscope is different from that of a classical optical sensor, the perspective projection model and the parallel projection model are considered and compared with distortion models. Experiments are realized by varying the position and the orientation of a multi-scale chessboard calibration pattern from 300× to 10,000×. The experimental results show the efficiency and the accuracy of this approach.

  19. Scanning electron microscopic study of the tongue in the Oriental scops owl (Otus scops).

    PubMed

    Emura, Shoichi; Okumura, Toshihiko; Chen, Huayue

    2009-05-01

    The dorsal lingual surface of an adult owl (Otus scops) was examined by scanning electron microscopy. The tongue of the adult owl was about 1 cm long. Three parts were distinguished in the dorsal surface of the tongue: the apex, the body and the root of the tongue. The conical region between the lingual apex and lingual root was very wide area. The conical papillae of the lingual body were inclined toward the posterior of the tongue. At low magnification of scanning electron microscopy, the desquamated cells were observed in the entire dorsal surface of the lingual apex. The connective tissue cores of the epithelium of the lingual apex showed the rod-shaped protrusions. The border between the lingual apex and body was clear and the small conical papillae were observed in the lingual body. The small and large conical papillae were observed on the lingual body. The many openings of the lingual glands existed in the lingual body and lingual root.

  20. Gastroesophageal junction of Anatolian shepherd dog; a study by topographic anatomy, scanning electron and light microscopy.

    PubMed

    Alsafy, M A M; El-Gendy, S A A

    2012-03-01

    The aim of this study was to cast a spotlight on the topography and to point out the clinical importance of the gastroesophageal junction (GEJ) in Anatolian Shepherd dogs. Nine Anatolian Shepherd dogs were used to study the morphology of the GEJ. The esophagus was appeared has a portion within the thoracic cavity while no portion of the esophagus presented within the abdominal cavity that documented the absence of the intra-abdominal portion in all studied dogs. The topographic anatomy, scanning electron and light microscopic examinations revealed that the gastroesophageal junction was located at the level of the phrenico-esophageal ligament (PEL) inside the esophageal hiatus. Our results were distinguished the morphology of the esophageal and gastric cardiac mucosa at the level of the gastroesophageal junction by the scanning electron micrographs. The light microscopical examination was explained the PEL attached to the esophageal side in one dog and to the gastric cardiac side in three dogs.

  1. Depth Sectioning with the Aberration-Corrected Scanning Transmission Electron Microscope

    SciTech Connect

    Borisevich, Albina Y; Lupini, Andrew R; Pennycook, Stephen J

    2006-01-01

    The ability to correct the aberrations of the probe-forming lens in the scanning transmission electron microscope provides not only a significant improvement in transverse resolution but in addition brings depth resolution at the nanometer scale. Aberration correction therefore opens up the possibility of 3D imaging by optical sectioning. Here we develop a definition for the depth resolution for scanning transmission electron microscope depth sectioning and present initial results from this method. Objects such as catalytic metal clusters and single atoms on various support materials are imaged in three dimensions with a resolution of several nanometers. Effective focal depth is determined by statistical analysis and the contributing factors are discussed. Finally, current challenges and future capabilities available through new instruments are discussed.

  2. Accurate Nanoscale Crystallography in Real-Space Using Scanning Transmission Electron Microscopy.

    PubMed

    Dycus, J Houston; Harris, Joshua S; Sang, Xiahan; Fancher, Chris M; Findlay, Scott D; Oni, Adedapo A; Chan, Tsung-Ta E; Koch, Carl C; Jones, Jacob L; Allen, Leslie J; Irving, Douglas L; LeBeau, James M

    2015-08-01

    Here, we report reproducible and accurate measurement of crystallographic parameters using scanning transmission electron microscopy. This is made possible by removing drift and residual scan distortion. We demonstrate real-space lattice parameter measurements with <0.1% error for complex-layered chalcogenides Bi2Te3, Bi2Se3, and a Bi2Te2.7Se0.3 nanostructured alloy. Pairing the technique with atomic resolution spectroscopy, we connect local structure with chemistry and bonding. Combining these results with density functional theory, we show that the incorporation of Se into Bi2Te3 causes charge redistribution that anomalously increases the van der Waals gap between building blocks of the layered structure. The results show that atomic resolution imaging with electrons can accurately and robustly quantify crystallography at the nanoscale.

  3. Scanning electron microscopy analysis of experimental bone hacking trauma of the mandible.

    PubMed

    Alunni-Perret, Véronique; Borg, Cybèle; Laugier, Jean-Pierre; Bertrand, Marie-France; Staccini, Pascal; Bolla, Marc; Quatrehomme, Gérald; Muller-Bolla, Michèle

    2010-12-01

    The authors report on a macroscopic and microscopic study of human mandible bone lesions achieved by a single-blade knife and a hatchet. The aim of this work was to complete the previous data (scanning electron microscopy analysis of bone lesions made by a single-blade knife and a hatchet, on human femurs) and to compare the lesions of the femur with those of the mandible. The results indicate that the mandible is a more fragile bone, but the features observed on the mandible are quite similar to those previously observed on the femur. This work spells out the main scanning electron microscopy characteristics of sharp (bone cutting) and blunt (exerting a pressure on the bone) mechanisms on human bone. Weapon characteristics serve to explain all of these features.

  4. Visualization of Aspergillus fumigatus biofilms with Scanning Electron Microscopy and Variable Pressure-Scanning Electron Microscopy: A comparison of processing techniques.

    PubMed

    Joubert, Lydia-Marie; Ferreira, Jose Ag; Stevens, David A; Nazik, Hasan; Cegelski, Lynette

    2017-01-01

    Aspergillus fumigatus biofilms consist of a three-dimensional network of cellular hyphae and extracellular matrix. They are involved in infections of immune-compromised individuals, particularly those with cystic fibrosis. These structures are associated with persistence of infection, resistance to host immunity, and antimicrobial resistance. Thorough understanding of structure and function is imperative in the design of therapeutic drugs. Optimization of processing parameters, including aldehyde fixation, heavy metal contrasting, drying techniques and Ionic Liquid treatment, was undertaken for an ultrastructural approach to understand cellular and extracellular biofilm components. Conventional and Variable Pressure Scanning Electron Microscopy were applied to analyze the structure of biofilms attached to plastic and formed at an air-liquid interface.

  5. Transient of scanning electron microscopic images for a buried microstructure in insulators

    SciTech Connect

    Zhang Haibo; Li Daoyu; Li Weiqin

    2007-12-15

    We clarify the transient process and its mechanism of scanning electron microscope (SEM) images of a trench microstructure buried in insulators. First, interface charges of primary electrons trapped on the trench are derived from the charging model of a capacitor considering the electron beam induced current, and the surface potential is therefore assumed. The SEM signal current is then determined from its simplified relation with the surface potential. Calculated profiles of the secondary electron (SE) signal current and their time-evolution behaviors can well fit the transient of the experimental SEM images. Results show that the variation of the surface potential due to the transient interface charges and the effect of SE redistribution result in transients of the SEM imaging signal and the image width of the buried trench.

  6. Scanning tunneling spectroscopy of inhomogeneous electronic structure in monolayer and bilayer graphene on SiC

    NASA Astrophysics Data System (ADS)

    Brar, Victor W.; Zhang, Yuanbo; Yayon, Yossi; Ohta, Taisuke; McChesney, Jessica L.; Bostwick, Aaron; Rotenberg, Eli; Horn, Karsten; Crommie, Michael F.

    2007-09-01

    The authors present a scanning tunneling spectroscopy (STS) study of the local electronic structure of single and bilayer graphene grown epitaxially on a SiC(0001) surface. Low voltage topographic images reveal fine, atomic-scale carbon networks, whereas higher bias images are dominated by emergent spatially inhomogeneous large-scale structure similar to a carbon-rich reconstruction of SiC(0001). STS spectroscopy shows an ˜100meV gaplike feature around zero bias for both monolayer and bilayer graphene/SiC, as well as significant spatial inhomogeneity in electronic structure above the gap edge. Nanoscale structure at the SiC/graphene interface is seen to correlate with observed electronic spatial inhomogeneity. These results are relevant for potential devices involving electronic transport or tunneling in graphene/SiC.

  7. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    NASA Astrophysics Data System (ADS)

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

    2016-02-01

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.

  8. Scanning electron acoustic microscopy of residual stresses in ceramics: Theory and experiment

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Qian, Menglu

    1992-01-01

    Several reviews have highlighted a number of applications of scanning electron acoustic microscopy (SEAM) to metals and semiconductors which show that SEAM can provide new information on surface and near-surface features of such materials, but there have been few studies attempting to determine the capabilities of SEAM for characterizing ceramic materials. We have recently observed image contrast in SEAM from residual stress fields induced in brittle materials by Vickers indentations that is strongly dependent on the electron beam chopping frequency. We have also recently developed a three-dimensional mathematical model of signal generation and contrast in SEAM, appropriate to the brittle materials studied, that we use as a starting point in this paper for modeling the effect of residual stress fields on the generated electron acoustic signal. The influence of the electron beam chopping frequency is also considered under restrictive assumptions.

  9. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    SciTech Connect

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

    2016-02-29

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Ultimately, simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.

  10. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry.

    PubMed

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R; Chess, Jordan; McMorran, Benjamin J; Czarnik, Cory; Rose, Harald H; Ercius, Peter

    2016-02-29

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.

  11. Scanning electron microscopy of egg hatching of Anopheles albimanus (Diptera: Culicidae).

    PubMed

    Rodriguez, M H; Orozco, A; Chavez, B; Martinez-Palomo, A

    1992-09-01

    Scanning electron and light microscopic observations showed that egg hatching in Anopheles albimanus Wiedemann is aided by a chisel-shaped spine. This hatching tooth is surrounded by a thin flexible membrane fixed to a groove in the head of the larvae. Increased intracranial pressure may force the spine against the egg shell until a fissure is produced. Further opening of the egg is achieved by movements of the head and the entire body of the larva.

  12. Spectrometric analysis and scanning electronic microscopy of two pleural plaques from mediaeval Portuguese period.

    PubMed

    Fernandes, T; Granja, R; Thillaud, P L

    2014-01-01

    During an archaeological excavation at a mediaeval monastery (Flor da Rosa, Crato, Portugal), a skeleton of a adult woman was found with two calcifications in the thoracic cage. The location and the macroscopic analysis of the calcifications allowed them to be assigned as pleural plaques. Spectrometric analysis and scanning electronic microscopy enabled to establish that it originated with an infectious process. These results associated with the lesions found in the ribs and vertebrae strongly suggest tuberculosis as the cause of these pleural plaques.

  13. Scanning electron microscopy of a pink inclusion from the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Grossman, L.; Fruland, R. M.; Mckay, D. S.

    1975-01-01

    A scanning electron microscope study of a fine-grained, pin, Ca-rich inclusion from the Allende meteorite has revealed strong evidence for direct condensation of its constituent minerals from a vapor. This observation extends to the alkali-bearing phases in addition to the Ca-, Al-silicates and suggests that the feldspathoids as well as the refractory silicates are solar nebular condensates.

  14. Novel Automatic Electrochemical-mechanical Polishing (ECMP) of Metals for Scanning Electron Microscopy (Postprint)

    DTIC Science & Technology

    2010-03-23

    Micron 41 (2010) 615–621 619 Fig. 4 . XPS binding energy (eV) versus sputtering time (s) results for the Ti 2p peaks for the titanium samples: (a...improved the IQ values. 4 . Conclusions The electrochemical–mechanical polishing system (ECMP) removed material from titanium and nickel alloys at a...March 2014 4 . TITLE AND SUBTITLE NOVEL AUTOMATIC ELECTROCHEMICAL-MECHANICAL POLISHING (ECMP) OF METALS FOR SCANNING ELECTRON MICROSCOPY

  15. Cryo-scanning electron microscopy and light microscopy for the study of fungi interactions.

    PubMed

    Sempere, F; Santamarina, M P

    2011-03-01

    The application of the cryo-scanning electron microscopy and light microscopy for the study of the interactions at different environmental conditions between Penicillium oxalicum and Fusarium verticillioides is described. A dual microculture was developed for the light microscopy analysis of the interaction. The microscope and macroscopic examinations were compared. Analysis of Petri plates revealed that F. verticillioides was a competitor for space and nutrients while P. oxalicum was a mycoparasite under the microscopic observations.

  16. Ultra structural studies of the surface of Hymenolepis nana by scanning and transmission electron microscopy.

    PubMed

    Abouzakham, A A; Romia, S A; Hegazi, M M

    1990-06-01

    Scanning electron microscopy of the surface of Hymenolepis nana indicated that dense populations of microtriches occur on scolex proper, suckers and strobila, with an average density of 20/micron2. The excellent preservation of microtriches proves the efficacy of the critical point drying method for preparing cestodes for study of SEM. The cytological structure of the tegument of H. nana corresponds in general to that of other tapeworms.

  17. Multi-Channel Electronically Scanned Cryogenic Pressure Sensor And Method For Making Same

    NASA Technical Reports Server (NTRS)

    Chapman, John J. (Inventor); Hopson, Purnell, Jr. (Inventor); Holloway, Nancy M. (Inventor)

    2001-01-01

    A miniature, multi-channel, electronically scanned pressure measuring device uses electrostatically bonded silicon dies in a multi-element array. These dies are bonded at specific sites on a glass, pre-patterned substrate. Thermal data is multiplexed and recorded on each individual pressure measuring diaphragm. The device functions in a cryogenic environment without the need of heaters to keep the sensor at constant temperatures.

  18. [Study of the root nodules in some species of the Papilionaceae subfamily by scanning electron microscopy].

    PubMed

    Novikova, T I; Gordienko, N Ia

    2001-01-01

    Nitrogen-fixing nodules from 16 species in 6 tribes of the sub-family Papilionaceae have been examined by scanning electron microscopy. The structure of infection threads was similar in all the studied papilionoid species except Lupinus polyphillus. In this species the infection threads were found in young nodules only. The morphology of bacterioids and the character of their "package" are determined by the host plant genotype. The obtained results are discussed in relation to the evolution of the legumes.

  19. Scanning electron microscopy of lunar regolith from the Sea of Fertility

    NASA Technical Reports Server (NTRS)

    Antoshin, M. K.; Ilin, N. P.; Spivak, G. V.

    1974-01-01

    Scanning electron microscopy was used in studying the morphology and cathodoluminescence of lunar regolith particles. Surface and structure of two groups of particles are differentiated: (1) Crystalline with well defined facets and spalling surfaces, which are grains of minerals and rock fragments: and (2) amorphous, fused, and partially or entirely glazed particles. Local melting of particles and the round openings on their surfaces are attributed to secondary influence on the regolith of factors of lunar weathering and above all micrometeoric impacts.

  20. 3D scanning electron microscopy applied to surface characterization of fluorosed dental enamel.

    PubMed

    Limandri, Silvina; Galván Josa, Víctor; Valentinuzzi, María Cecilia; Chena, María Emilia; Castellano, Gustavo

    2016-05-01

    The enamel surfaces of fluorotic teeth were studied by scanning electron stereomicroscopy. Different whitening treatments were applied to 25 pieces to remove stains caused by fluorosis and their surfaces were characterized by stereomicroscopy in order to obtain functional and amplitude parameters. The topographic features resulting for each treatment were determined through these parameters. The results obtained show that the 3D reconstruction achieved from the SEM stereo pairs is a valuable potential alternative for the surface characterization of this kind of samples.

  1. Direct visualization of lithium via annular bright field scanning transmission electron microscopy: a review.

    PubMed

    Findlay, Scott David; Huang, Rong; Ishikawa, Ryo; Shibata, Naoya; Ikuhara, Yuichi

    2017-02-08

    Annular bright field (ABF) scanning transmission electron microscopy has proven able to directly image lithium columns within crystalline environments, offering much insight into the structure and properties of lithium-ion battery materials. We summarize the image formation mechanisms underpinning ABF imaging, review the experimental application of this technique to imaging lithium in materials and overview the conditions that help maximize the visibility of lithium columns.

  2. Reliable strain measurement in transistor arrays by robust scanning transmission electron microscopy

    SciTech Connect

    Kim, Suhyun; Kim, Joong Jung; Jung, Younheum; Lee, Kyungwoo; Byun, Gwangsun; Hwang, KyoungHwan; Lee, Sunyoung; Lee, Kyupil

    2013-09-15

    Accurate measurement of the strain field in the channels of transistor arrays is critical for strain engineering in modern electronic devices. We applied atomic-resolution high-angle annular dark-field scanning transmission electron microscopy to quantitative measurement of the strain field in transistor arrays. The quantitative strain profile over 20 transistors was obtained with high reliability and a precision of 0.1%. The strain field was found to form homogeneously in the channels of the transistor arrays. Furthermore, strain relaxation due to the thin foil effect was quantitatively investigated for thicknesses of 35 to 275 nm.

  3. New views of materials through aberration-corrected scanning transmission electron microscopy.

    PubMed

    Pennycook, S J; Varela, M

    2011-01-01

    The successful correction of third-order and, more recently, fifth-order aberrations has enormously enhanced the capabilities of the scanning transmission electron microscope (STEM), by not only achieving record resolution, but also allowing near 100% efficiency for electron energy loss spectroscopy, and higher currents for two-dimensional spectrum imaging. These advances have meant that the intrinsic advantages of the STEM, incoherent imaging and simultaneous collection of multiple complementary images can now give new insights into many areas of materials physics. Here, we review a number of examples, mostly from the field of complex oxides, and look towards new directions for the future.

  4. Ultrahigh-resolution Scanning Transmission Microscopy with Sub-?ngstrom-Sized Electron Beams

    SciTech Connect

    Abe, E.; Pennycook, Stephen J

    2005-01-01

    The scanning transmission electron microscope(STEM)with an annular dark-field(ADF) detector provides atomic-resolution incoherent images, whose resolution is dominated, to a good approximation, by the size of convergent electron beams. Improving a spherical aberra- tion of microscope objective lenses has been successful in converging the beam into sub- scale, promising a remarkably higher resolution for STEM. Here we describe the performance of aberration-corrected 300kV-STEM - the world-best STEM available today. The results clearly demonstrate that a sub- ngstrom resolution has been indeed achieved for not only simple structures but also structurally complex systems(quasicrystals).

  5. Visualizing Macromolecular Complexes with In Situ Liquid Scanning Transmission Electron Microscopy

    SciTech Connect

    Evans, James E.; Jungjohann, K. L.; Wong, Peony C. K.; Chiu, Po-Lin; Dutrow, Gavin H.; Arslan, Ilke; Browning, Nigel D.

    2012-11-01

    A central focus of biological research is understanding the structure/function relationship of macromolecular protein complexes. Yet conventional transmission electron microscopy techniques are limited to static observations. Here we present the first direct images of purified macromolecular protein complexes using in situ liquid scanning transmission electron microscopy. Our results establish the capability of this technique for visualizing the interface between biology and nanotechnology with high fidelity while also probing the interactions of biomolecules within solution. This method represents an important advancement towards allowing future high-resolution observations of biological processes and conformational dynamics in real-time.

  6. The Scanning Electron Microscope As An Accelerator For The Undergraduate Advanced Physics Laboratory

    SciTech Connect

    Peterson, Randolph S.; Berggren, Karl K.; Mondol, Mark

    2011-06-01

    Few universities or colleges have an accelerator for use with advanced physics laboratories, but many of these institutions have a scanning electron microscope (SEM) on site, often in the biology department. As an accelerator for the undergraduate, advanced physics laboratory, the SEM is an excellent substitute for an ion accelerator. Although there are no nuclear physics experiments that can be performed with a typical 30 kV SEM, there is an opportunity for experimental work on accelerator physics, atomic physics, electron-solid interactions, and the basics of modern e-beam lithography.

  7. Visualizing macromolecular complexes with in situ liquid scanning transmission electron microscopy.

    PubMed

    Evans, James E; Jungjohann, Katherine L; Wong, Peony C K; Chiu, Po-Lin; Dutrow, Gavin H; Arslan, Ilke; Browning, Nigel D

    2012-11-01

    A central focus of biological research is understanding the structure/function relationship of macromolecular protein complexes. Yet conventional transmission electron microscopy techniques are limited to static observations. Here we present the first direct images of purified macromolecular protein complexes using in situ liquid scanning transmission electron microscopy. Our results establish the capability of this technique for visualizing the interface between biology and nanotechnology with high fidelity while also probing the interactions of biomolecules within solution. This method represents an important advancement towards allowing future high-resolution observations of biological processes and conformational dynamics in real-time.

  8. Characterization of LiBC by phase-contrast scanning transmission electron microscopy.

    PubMed

    Krumeich, Frank; Wörle, Michael; Reibisch, Philipp; Nesper, Reinhard

    2014-08-01

    LiBC was used as a model compound for probing the applicability of phase-contrast (PC) imaging in an aberration-corrected scanning transmission electron microscope (STEM) to visualize lithium distributions. In the LiBC structure, boron and carbon are arranged to hetero graphite layers between which lithium is incorporated. The crystal structure is reflected in the PC-STEM images recorded perpendicular to the layers. The experimental images and their defocus dependence match with multi-slice simulations calculated utilizing the reciprocity principle. The observation that a part of the Li positions is not occupied is likely an effect of the intense electron beam triggering Li displacement.

  9. Thirty per cent contrast in secondary-electron imaging by scanning field-emission microscopy

    NASA Astrophysics Data System (ADS)

    Zanin, D. A.; De Pietro, L. G.; Peter, Q.; Kostanyan, A.; Cabrera, H.; Vindigni, A.; Bähler, Th.; Pescia, D.; Ramsperger, U.

    2016-11-01

    We perform scanning tunnelling microscopy (STM) in a regime where primary electrons are field-emitted from the tip and excite secondary electrons out of the target-the scanning field-emission microscopy regime (SFM). In the SFM mode, a secondary-electron contrast as high as 30% is observed when imaging a monoatomic step between a clean W(110)- and an Fe-covered W(110)-terrace. This is a figure of contrast comparable to STM. The apparent width of the monoatomic step attains the 1 nm mark, i.e. it is only marginally worse than the corresponding width observed in STM. The origin of the unexpected strong contrast in SFM is the material dependence of the secondary-electron yield and not the dependence of the transported current on the tip-target distance, typical of STM: accordingly, we expect that a technology combining STM and SFM will highlight complementary aspects of a surface while simultaneously making electrons, selected with nanometre spatial precision, available to a macroscopic environment for further processing.

  10. Thirty per cent contrast in secondary-electron imaging by scanning field-emission microscopy

    PubMed Central

    De Pietro, L. G.; Peter, Q.; Kostanyan, A.; Cabrera, H.; Vindigni, A.; Bähler, Th.; Pescia, D.; Ramsperger, U.

    2016-01-01

    We perform scanning tunnelling microscopy (STM) in a regime where primary electrons are field-emitted from the tip and excite secondary electrons out of the target—the scanning field-emission microscopy regime (SFM). In the SFM mode, a secondary-electron contrast as high as 30% is observed when imaging a monoatomic step between a clean W(110)- and an Fe-covered W(110)-terrace. This is a figure of contrast comparable to STM. The apparent width of the monoatomic step attains the 1 nm mark, i.e. it is only marginally worse than the corresponding width observed in STM. The origin of the unexpected strong contrast in SFM is the material dependence of the secondary-electron yield and not the dependence of the transported current on the tip–target distance, typical of STM: accordingly, we expect that a technology combining STM and SFM will highlight complementary aspects of a surface while simultaneously making electrons, selected with nanometre spatial precision, available to a macroscopic environment for further processing. PMID:27956876

  11. Thirty per cent contrast in secondary-electron imaging by scanning field-emission microscopy.

    PubMed

    Zanin, D A; De Pietro, L G; Peter, Q; Kostanyan, A; Cabrera, H; Vindigni, A; Bähler, Th; Pescia, D; Ramsperger, U

    2016-11-01

    We perform scanning tunnelling microscopy (STM) in a regime where primary electrons are field-emitted from the tip and excite secondary electrons out of the target-the scanning field-emission microscopy regime (SFM). In the SFM mode, a secondary-electron contrast as high as 30% is observed when imaging a monoatomic step between a clean W(110)- and an Fe-covered W(110)-terrace. This is a figure of contrast comparable to STM. The apparent width of the monoatomic step attains the 1 nm mark, i.e. it is only marginally worse than the corresponding width observed in STM. The origin of the unexpected strong contrast in SFM is the material dependence of the secondary-electron yield and not the dependence of the transported current on the tip-target distance, typical of STM: accordingly, we expect that a technology combining STM and SFM will highlight complementary aspects of a surface while simultaneously making electrons, selected with nanometre spatial precision, available to a macroscopic environment for further processing.

  12. A high-voltage scanning electron microscopy system for in situ electromigration testing

    NASA Astrophysics Data System (ADS)

    Doan, J. C.; Lee, S.; Lee, S.-H.; Meier, N. E.; Bravman, J. C.; Flinn, P. A.; Marieb, T. N.; Madden, M. C.

    2000-07-01

    An apparatus has been constructed to conduct electromigration tests on realistic specimens while simultaneously observing them at relatively high magnification. A scanning transmission electron microscope has been converted into a high-voltage scanning electron microscope (HVSEM) with a large specimen chamber. By imaging with high-energy electrons (120 keV) and detecting backscattered electrons, voids in metal lines can be viewed through passivation layers. The HVSEM has a resolution of 50 nm through 1 μm of passivation. We have constructed instrumentation to heat and pass current through interconnect structures, while they are inside the electron microscope. Presently, the specimen temperature can be as high as 350 °C and is maintained constant to within 0.1 °C. The resistances of interconnects are measured with a precision of 0.05% during an experiment. Testing the lines at moderately accelerated conditions requires great stability of the microscope and instrumentation as well as full automation of the data collection. These requirements have been met, and metallization lines can be tested for several weeks with minimal operator intervention. Digital images of an entire 300-μm-long test structure as well as electrical data are stored automatically every few minutes during a test. The hundreds to thousands of pictures are analyzed using digital image processing techniques to extract void positions and sizes as a function of time. We use this system to characterize electromigration failure in advanced interconnect structures and to test existing theories on electromigration phenomenon.

  13. Comparison of Electron Imaging Modes for Dimensional Measurements in the Scanning Electron Microscope.

    PubMed

    Postek, Michael T; Vladár, András E; Villarrubia, John S; Muto, Atsushi

    2016-08-01

    Dimensional measurements from secondary electron (SE) images were compared with those from backscattered electron (BSE) and low-loss electron (LLE) images. With the commonly used 50% threshold criterion, the lines consistently appeared larger in the SE images. As the images were acquired simultaneously by an instrument with the capability to operate detectors for both signals at the same time, the differences cannot be explained by the assumption that contamination or drift between images affected the SE, BSE, or LLE images differently. Simulations with JMONSEL, an electron microscope simulator, indicate that the nanometer-scale differences observed on this sample can be explained by the different convolution effects of a beam with finite size on signals with different symmetry (the SE signal's characteristic peak versus the BSE or LLE signal's characteristic step). This effect is too small to explain the >100 nm discrepancies that were observed in earlier work on different samples. Additional modeling indicates that those discrepancies can be explained by the much larger sidewall angles of the earlier samples, coupled with the different response of SE versus BSE/LLE profiles to such wall angles.

  14. Comparison of Electron Imaging Modes for Dimensional Measurements in the Scanning Electron Microscope†

    PubMed Central

    Postek, Michael T.; Vladár, András E.; Villarrubia, John S.; Muto, Atsushi

    2016-01-01

    Dimensional measurements from secondary electron (SE) images were compared with those from backscattered electron (BSE) and low-loss electron (LLE) images. With the commonly used 50% threshold criterion, the lines consistently appeared larger in the SE images. As the images were acquired simultaneously by an instrument with the capability to operate detectors for both signals at the same time, the differences cannot be explained by the assumption that contamination or drift between images affected the SE, BSE, or LLE images differently. Simulations with JMONSEL, an electron microscope simulator, indicate that the nanometer-scale differences observed on this sample can be explained by the different convolution effects of a beam with finite size on signals with different symmetry (the SE signal’s characteristic peak versus the BSE or LLE signal’s characteristic step). This effect is too small to explain the > 100 nm discrepancies that were observed in earlier work on different samples. Additional modeling indicates that those discrepancies can be explained by the much larger sidewall angles of the earlier samples, coupled with the different response of SE versus BSE/LLE profiles to such wall angles. PMID:27452278

  15. Design of 220 GHz electronically scanned reflectarrays for confocal imaging systems

    NASA Astrophysics Data System (ADS)

    Hedden, Abigail S.; Dietlein, Charles R.; Wikner, David A.

    2012-09-01

    The authors analyze properties of a 220 GHz imaging system that uses a scanned reflectarray to perform electronic beam scanning of a confocal imager for applications including imaging meter-sized fields of view at 50 m standoff. Designs incorporating reflectarrays with confocal imagers have not been examined previously at these frequencies. We examine tradeoffs between array size, overall system size, and number of achievable image pixels resulting in a realistic architecture capable of meeting the needs of our application. Impacts to imaging performance are assessed through encircled energy calculations, beam pointing accuracy, and examining the number and intensity of quantization lobes that appear over the scan ranges of interest. Over the desired scan range, arrays with 1 and 2-bit phase quantization showed similar array main beam energy efficiencies. Two-bit phase quantization is advantageous in terms of pointing angle error, resulting in errors of at most 15% of the diffraction-limited beam size. However, both phase quantization cases considered resulted in spurious returns over the scan range of interest and other array layouts should be examined to eliminate potential imaging artifacts.

  16. Implementation of subcellular water mapping by electron energy loss spectroscopy in a medium-voltage scanning transmission electron microscope.

    PubMed

    Terryn, C; Michel, J; Thomas, X; Laurent-Maquin, D; Balossier, G

    2004-07-01

    The water concentration in biological cells plays a predominant role in cellular life. Using electron energy loss spectroscopy, the feasibility to measure the water content in cells has already been demonstrated. In this paper, we present an upgrade of water measurement in hydrated cryosections by spectrum imaging mode in a medium-voltage scanning transmission electron microscope. The electron energy loss spectra are recorded in spectrum imaging mode in a 2(n)x2(n) pixels array. Each spectrum is processed in order to determine the water mass content in the corresponding pixel. Then a parametric image is obtained in which grey levels are related to water concentration. In this image, it is possible to recognize the different subcellular compartments. By averaging the water concentration over the relevant pixels, we can determine the water mass content in the concerned subcellular compartment. As an example, we present water mass content measurement at subcellular level in rat hepatocytes.

  17. High-energy-resolution monochromator for aberration-corrected scanning transmission electron microscopy/electron energy-loss spectroscopy.

    PubMed

    Krivanek, Ondrej L; Ursin, Jonathan P; Bacon, Neil J; Corbin, George J; Dellby, Niklas; Hrncirik, Petr; Murfitt, Matthew F; Own, Christopher S; Szilagyi, Zoltan S

    2009-09-28

    An all-magnetic monochromator/spectrometer system for sub-30 meV energy-resolution electron energy-loss spectroscopy in the scanning transmission electron microscope is described. It will link the energy being selected by the monochromator to the energy being analysed by the spectrometer, without resorting to decelerating the electron beam. This will allow it to attain spectral energy stability comparable to systems using monochromators and spectrometers that are raised to near the high voltage of the instrument. It will also be able to correct the chromatic aberration of the probe-forming column. It should be able to provide variable energy resolution down to approximately 10 meV and spatial resolution less than 1 A.

  18. Challenges of microtome-based serial block-face scanning electron microscopy in neuroscience.

    PubMed

    Wanner, A A; Kirschmann, M A; Genoud, C

    2015-08-01

    Serial block-face scanning electron microscopy (SBEM) is becoming increasingly popular for a wide range of applications in many disciplines from biology to material sciences. This review focuses on applications for circuit reconstruction in neuroscience, which is one of the major driving forces advancing SBEM. Neuronal circuit reconstruction poses exceptional challenges to volume EM in terms of resolution, field of view, acquisition time and sample preparation. Mapping the connections between neurons in the brain is crucial for understanding information flow and information processing in the brain. However, information on the connectivity between hundreds or even thousands of neurons densely packed in neuronal microcircuits is still largely missing. Volume EM techniques such as serial section TEM, automated tape-collecting ultramicrotome, focused ion-beam scanning electron microscopy and SBEM (microtome serial block-face scanning electron microscopy) are the techniques that provide sufficient resolution to resolve ultrastructural details such as synapses and provides sufficient field of view for dense reconstruction of neuronal circuits. While volume EM techniques are advancing, they are generating large data sets on the terabyte scale that require new image processing workflows and analysis tools. In this review, we present the recent advances in SBEM for circuit reconstruction in neuroscience and an overview of existing image processing and analysis pipelines.

  19. Morphological aspects of Angiostrongylus costaricensis by light and scanning electron microscopy.

    PubMed

    Rebello, Karina M; Menna-Barreto, Rubem F S; Chagas-Moutinho, Vanessa A; Mota, Ester M; Perales, Jonas; Neves-Ferreira, Ana Gisele C; Oliveira-Menezes, Aleksandra; Lenzi, Henrique

    2013-09-01

    Angiostrongylus costaricensis is a parasitic nematode that can cause severe gastrointestinal disease, known as abdominal angiostrongiliasis, in humans. This paper presents the characterization of first- and third-stage larvae and male and female adult worms of A. costaricensis by scanning electron and light microscopy. Several novel anatomical structures were identified by scanning electron microscopy, including details of the cuticular striations of the spicules in male worms and a protective flap of the cuticle covering the vulvar aperture in female worms. Other taxonomic features revealed by light microscopy include the gubernaculum and the esophageal-intestinal valve. The use of two microscopy techniques allowed a detailed characterization of the morphology of this nematode. A number of previously identified taxonomic features, such as the striated nature of the spicules and the lateral alae were confirmed; however, the use of scanning electron microscopy resulted in a reassessment of the correct number of papillae distributed around the oral opening and behind the cloacal opening. These observations, in combination with light microscopy-based characterization of the gubernaculum and esophageal valves, have allowed a more detailed description of this nematode taxonomy.

  20. In situ Scanning Electron Microscopy of Silicon Anode Reactions in Lithium-Ion Batteries during Charge/Discharge Processes.

    PubMed

    Chen, Chih-Yao; Sano, Teruki; Tsuda, Tetsuya; Ui, Koichi; Oshima, Yoshifumi; Yamagata, Masaki; Ishikawa, Masashi; Haruta, Masakazu; Doi, Takayuki; Inaba, Minoru; Kuwabata, Susumu

    2016-10-26

    A comprehensive understanding of the charge/discharge behaviour of high-capacity anode active materials, e.g., Si and Li, is essential for the design and development of next-generation high-performance Li-based batteries. Here, we demonstrate the in situ scanning electron microscopy (in situ SEM) of Si anodes in a configuration analogous to actual lithium-ion batteries (LIBs) with an ionic liquid (IL) that is expected to be a functional LIB electrolyte in the future. We discovered that variations in the morphology of Si active materials during charge/discharge processes is strongly dependent on their size and shape. Even the diffusion of atomic Li into Si materials can be visualized using a back-scattering electron imaging technique. The electrode reactions were successfully recorded as video clips. This in situ SEM technique can simultaneously provide useful data on, for example, morphological variations and elemental distributions, as well as electrochemical data.

  1. In situ Scanning Electron Microscopy of Silicon Anode Reactions in Lithium-Ion Batteries during Charge/Discharge Processes

    NASA Astrophysics Data System (ADS)

    Chen, Chih-Yao; Sano, Teruki; Tsuda, Tetsuya; Ui, Koichi; Oshima, Yoshifumi; Yamagata, Masaki; Ishikawa, Masashi; Haruta, Masakazu; Doi, Takayuki; Inaba, Minoru; Kuwabata, Susumu

    2016-10-01

    A comprehensive understanding of the charge/discharge behaviour of high-capacity anode active materials, e.g., Si and Li, is essential for the design and development of next-generation high-performance Li-based batteries. Here, we demonstrate the in situ scanning electron microscopy (in situ SEM) of Si anodes in a configuration analogous to actual lithium-ion batteries (LIBs) with an ionic liquid (IL) that is expected to be a functional LIB electrolyte in the future. We discovered that variations in the morphology of Si active materials during charge/discharge processes is strongly dependent on their size and shape. Even the diffusion of atomic Li into Si materials can be visualized using a back-scattering electron imaging technique. The electrode reactions were successfully recorded as video clips. This in situ SEM technique can simultaneously provide useful data on, for example, morphological variations and elemental distributions, as well as electrochemical data.

  2. In situ Scanning Electron Microscopy of Silicon Anode Reactions in Lithium-Ion Batteries during Charge/Discharge Processes

    PubMed Central

    Chen, Chih-Yao; Sano, Teruki; Tsuda, Tetsuya; Ui, Koichi; Oshima, Yoshifumi; Yamagata, Masaki; Ishikawa, Masashi; Haruta, Masakazu; Doi, Takayuki; Inaba, Minoru; Kuwabata, Susumu

    2016-01-01

    A comprehensive understanding of the charge/discharge behaviour of high-capacity anode active materials, e.g., Si and Li, is essential for the design and development of next-generation high-performance Li-based batteries. Here, we demonstrate the in situ scanning electron microscopy (in situ SEM) of Si anodes in a configuration analogous to actual lithium-ion batteries (LIBs) with an ionic liquid (IL) that is expected to be a functional LIB electrolyte in the future. We discovered that variations in the morphology of Si active materials during charge/discharge processes is strongly dependent on their size and shape. Even the diffusion of atomic Li into Si materials can be visualized using a back-scattering electron imaging technique. The electrode reactions were successfully recorded as video clips. This in situ SEM technique can simultaneously provide useful data on, for example, morphological variations and elemental distributions, as well as electrochemical data. PMID:27782200

  3. Atomic imaging using secondary electrons in a scanning transmission electron microscope: experimental observations and possible mechanisms.

    PubMed

    Inada, H; Su, D; Egerton, R F; Konno, M; Wu, L; Ciston, J; Wall, J; Zhu, Y

    2011-06-01

    We report detailed investigation of high-resolution imaging using secondary electrons (SE) with a sub-nanometer probe in an aberration-corrected transmission electron microscope, Hitachi HD2700C. This instrument also allows us to acquire the corresponding annular dark-field (ADF) images both simultaneously and separately. We demonstrate that atomic SE imaging is achievable for a wide range of elements, from uranium to carbon. Using the ADF images as a reference, we studied the SE image intensity and contrast as functions of applied bias, atomic number, crystal tilt, and thickness to shed light on the origin of the unexpected ultrahigh resolution in SE imaging. We have also demonstrated that the SE signal is sensitive to the terminating species at a crystal surface. A possible mechanism for atomic-scale SE imaging is proposed. The ability to image both the surface and bulk of a sample at atomic-scale is unprecedented, and can have important applications in the field of electron microscopy and materials characterization.

  4. Construction of a new type of low-energy scanning electron microscope with atomic resolution

    NASA Astrophysics Data System (ADS)

    Eastham, D. A.; Edmondson, P.; Donnelly, S.; Olsson, E.; Svensson, K.; Bleloch, A.

    2009-05-01

    We describe a new type of scanning electron microscope which works by directly imaging the electron field-emission sites on a nanotip. Electrons are extracted from the nanotip through a nanoscale aperture, accelerated in a high electric field and focussed to a spot using a microscale einzel lens. If the whole microscope (accelerating section and lens) and the focal length are both restricted in size to below 10 microns, then computer simulations show that the effects of aberration are extremely small and it is possible to have a system with approximately unit magnification, at electron energies as low as 300 eV. Thus a typical emission site of 1 nm diameter will produce an image of the same size and an atomic emission site with give a resolution of 0.1-0.2 nm (1-2 Å), and because the beam is not allowed to expand beyond 100nm in diameter the depth of field is large and the contribution to the beam spot size from chromatic aberrations is less than 0.02 nm (0.2 Å) for 500 eV electrons. Since it is now entirely possible to make stable atomic sized emitters (nanopyramids) it is expected that this instrument will have atomic resolution. Furthermore the brightness of the beam is determined only by the field-emission and can be up to a million times larger than in a typical (high-energy) electron microscope. The construction of this microscope, based on using a nanotip electron source which is mounted on a nanopositioner so that it can be positioned at the correct point adjacent to the microscope, entrance aperture, is described. In this geometry the scanning is achieved by moving the sample using piezos. Two methods for the construction of the microscope column are reviewed and the results of preliminary tests are described. The advantages of this low energy, bright-beam, electron microscope with atomic resolution are described. It can be used in either scanning mode or diffraction mode. The major advantage over existing microscopes is that because it works at very low

  5. Atomic-scale mapping of electronic structures across heterointerfaces by cross-sectional scanning tunneling microscopy.

    PubMed

    Chiu, Ya-Ping; Huang, Bo-Chao; Shih, Min-Chuan; Huang, Po-Cheng; Chen, Chun-Wei

    2015-09-04

    Interfacial science has received much attention recently based on the development of state-of-the-art analytical tools that can create and manipulate the charge, spin, orbital, and lattice degrees of freedom at interfaces. Motivated by the importance of nanoscale interfacial science that governs device operation, we present a technique to probe the electronic characteristics of heterointerfaces with atomic resolution. In this work, the interfacial characteristics of heteroepitaxial structures are investigated and the fundamental mechanisms that pertain in these systems are elucidated through cross-sectional scanning tunneling microscopy (XSTM). The XSTM technique is employed here to directly observe epitaxial interfacial structures and probe local electronic properties with atomic-level capability. Scanning tunneling microscopy and spectroscopy experiments with atomic precision provide insight into the origin and spatial distribution of electronic properties across heterointerfaces. The first part of this report provides a brief description of the cleavage technique and spectroscopy analysis in XSTM measurements. The second part addresses interfacial electronic structures of several model heterostructures in current condensed matter research using XSTM. Topics to be discussed include high-κ's/III-V's semiconductors, polymer heterojunctions, and complex oxide heterostructures, which are all material systems whose investigation using this technique is expected to benefit the research community. Finally, practical aspects and perspectives of using XSTM in interface science are presented.

  6. Variable Temperature Setup for Scanning Electron Microscopy in Liquids and Atmospheric Pressure Gaseous Environments

    NASA Astrophysics Data System (ADS)

    Al-Asadi, Ahmed; Zhang, Jie; Li, Jianbo; Denault, Lauraine; Potyrailo, Radislav; Kolmakov, Andrei

    2014-03-01

    A thermoelectric cooling / heating setup for commercial Quantomix QX WETSEM scanning electron microscopy environmental cells was designed and tested. This addition allows extending ambient pressure in situ studies to be conducted in a wide temperature range both in liquid and gaseous environments. Instead of cooling/heating the entire body of QX-WETCELL, ultrathin polyimide electron transparent membrane window supported by metal mesh on the top of the cell has been used as an agent for heat transfer to/ from the Pelltier element. A butterfly wing of Morph sulkowskyi has been used as a model object in the QX-WETCELL's chamber due to its unique micro/nanostructure and peculiar wettability behavior. The dynamics of the water desorption, condensation and freezing processes were observed complementary using both optical microscopy and Scanning Electron Microscopy in vivo. The observations revel that the initial droplet formation were most likely taking place on the top of the wing ridges due to the waxy component of its surface. In addition, The SEM observation showed that the high intensity electron beam can heat the butterfly wing locally delaying the water condensation and freezing processes.

  7. Atomic-scale mapping of electronic structures across heterointerfaces by cross-sectional scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Chiu, Ya-Ping; Huang, Bo-Chao; Shih, Min-Chuan; Huang, Po-Cheng; Chen, Chun-Wei

    2015-09-01

    Interfacial science has received much attention recently based on the development of state-of-the-art analytical tools that can create and manipulate the charge, spin, orbital, and lattice degrees of freedom at interfaces. Motivated by the importance of nanoscale interfacial science that governs device operation, we present a technique to probe the electronic characteristics of heterointerfaces with atomic resolution. In this work, the interfacial characteristics of heteroepitaxial structures are investigated and the fundamental mechanisms that pertain in these systems are elucidated through cross-sectional scanning tunneling microscopy (XSTM). The XSTM technique is employed here to directly observe epitaxial interfacial structures and probe local electronic properties with atomic-level capability. Scanning tunneling microscopy and spectroscopy experiments with atomic precision provide insight into the origin and spatial distribution of electronic properties across heterointerfaces. The first part of this report provides a brief description of the cleavage technique and spectroscopy analysis in XSTM measurements. The second part addresses interfacial electronic structures of several model heterostructures in current condensed matter research using XSTM. Topics to be discussed include high-κ‘s/III-V’s semiconductors, polymer heterojunctions, and complex oxide heterostructures, which are all material systems whose investigation using this technique is expected to benefit the research community. Finally, practical aspects and perspectives of using XSTM in interface science are presented.

  8. The probe profile and lateral resolution of scanning transmission electron microscopy of thick specimens.

    PubMed

    Demers, Hendrix; Ramachandra, Ranjan; Drouin, Dominique; de Jonge, Niels

    2012-06-01

    Lateral profiles of the electron probe of scanning transmission electron microscopy (STEM) were simulated at different vertical positions in a micrometers-thick carbon sample. The simulations were carried out using the Monte Carlo method in CASINO software. A model was developed to fit the probe profiles. The model consisted of the sum of a Gaussian function describing the central peak of the profile and two exponential decay functions describing the tail of the profile. Calculations were performed to investigate the fraction of unscattered electrons as a function of the vertical position of the probe in the sample. Line scans were also simulated over gold nanoparticles at the bottom of a carbon film to calculate the achievable resolution as a function of the sample thickness and the number of electrons. The resolution was shown to be noise limited for film thicknesses less than 1 μm. Probe broadening limited the resolution for thicker films. The validity of the simulation method was verified by comparing simulated data with experimental data. The simulation method can be used as quantitative method to predict STEM performance or to interpret STEM images of thick specimens.

  9. Application of low-vacuum scanning electron microscopy for renal biopsy specimens.

    PubMed

    Miyazaki, Hiroki; Uozaki, Hiroshi; Tojo, Akihiro; Hirashima, Sayuri; Inaga, Sumire; Sakuma, Kei; Morishita, Yasuyuki; Fukayama, Masashi

    2012-09-15

    Low-vacuum scanning electron microscopy (LV-SEM) has been developed which enables the observation of soft, moist, and electrically insulating materials without any pretreatment unlike conventional scanning electron microscopy, in which samples must be solid, dry and usually electrically conductive. The purpose of this study was to assess the usefulness of LV-SEM for renal biopsy specimens. We analyzed 20 renal biopsy samples obtained for diagnostic purposes. The sections were stained with periodic acid methenamine silver to enhance the contrast, and subsequently examined by LV-SEM. LV-SEM showed a precise and fine structure of the glomerulus in both formalin fixed paraffin and glutaraldehyde-osmium tetroxide-fixed epoxy resin sections up to 10,000-fold magnification. The spike formation on the basement membrane was clearly observed in the membranous nephropathy samples. Similarly to transmission electron microscopy, electron dense deposits were observed in the epoxy resin sections of the IgA nephropathy and membranous nephropathy samples. LV-SEM could accurately show various glomerular lesions at high magnification after a simple and rapid processing of the samples. We consider that this is a novel and useful diagnostic tool for renal pathologies.

  10. Liquid scanning transmission electron microscopy: imaging protein complexes in their native environment in whole eukaryotic cells.

    PubMed

    Peckys, Diana B; de Jonge, Niels

    2014-04-01

    Scanning transmission electron microscopy (STEM) of specimens in liquid, so-called Liquid STEM, is capable of imaging the individual subunits of macromolecular complexes in whole eukaryotic cells in liquid. This paper discusses this new microscopy modality within the context of state-of-the-art microscopy of cells. The principle of operation and equations for the resolution are described. The obtained images are different from those acquired with standard transmission electron microscopy showing the cellular ultrastructure. Instead, contrast is obtained on specific labels. Images can be recorded in two ways, either via STEM at 200 keV electron beam energy using a microfluidic chamber enclosing the cells, or via environmental scanning electron microscopy at 30 keV of cells in a wet environment. The first series of experiments involved the epidermal growth factor receptor labeled with gold nanoparticles. The labels were imaged in whole fixed cells with nanometer resolution. Since the cells can be kept alive in the microfluidic chamber, it is also feasible to detect the labels in unfixed, live cells. The rapid sample preparation and imaging allows studies of multiple whole cells.

  11. 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.

  12. A scanning and transmission electron microscopic analysis of the cerebral aqueduct in the rabbit.

    PubMed

    Meller, S T; Dennis, B J

    1993-09-01

    An examination of the surface of the cerebral aqueduct with the scanning electron microscope revealed that the walls of the cerebral aqueduct were so heavily ciliated that most of the ependymal surface was obscured, yet certain specialized supraependymal structures could be discerned lying on (or embedded within) this matt of cilia. These structures were determined by transmission electron microscopy and Golgi analysis to be either macrophages, supraependymal neurons, dendrites from medial periaqueductal gray neurons, or axons of unknown origin. Some axons, which were found to contain vesicles, appeared to make synaptic contacts with ependymal cells. Using the transmission electron microscope, the ependymal lining was found to consist of two different cell types: normal ependymal cells and tanycytes which have a long tapering basal process that was observed to contact blood vessels or, more rarely, seemed to terminate in relation to neuronal elements. While there have been previous reports on the structure of the third and lateral ventricles in other species, there are limited reports in the rabbit. The present report is not only the first description for the rabbit, but it is the first complete scanning and transmission electron microscopic analysis of the cerebral aqueduct in any species.

  13. Specimen preparation by ion beam slope cutting for characterization of ductile damage by scanning electron microscopy.

    PubMed

    Besserer, Hans-Bernward; Gerstein, Gregory; Maier, Hans Jürgen; Nürnberger, Florian

    2016-04-01

    To investigate ductile damage in parts made by cold sheet-bulk metal forming a suited specimen preparation is required to observe the microstructure and defects such as voids by electron microscopy. By means of ion beam slope cutting both a targeted material removal can be applied and mechanical or thermal influences during preparation avoided. In combination with scanning electron microscopy this method allows to examine voids in the submicron range and thus to analyze early stages of ductile damage. In addition, a relief structure is formed by the selectivity of the ion bombardment, which depends on grain orientation and microstructural defects. The formation of these relief structures is studied using scanning electron microscopy and electron backscatter diffraction and the use of this side effect to interpret the microstructural mechanisms of voids formation by plastic deformation is discussed. A comprehensive investigation of the suitability of ion beam milling to analyze ductile damage is given at the examples of a ferritic deep drawing steel and a dual phase steel.

  14. High-pressure freezing for scanning transmission electron tomography analysis of cellular organelles.

    PubMed

    Walther, Paul; Schmid, Eberhard; Höhn, Katharina

    2013-01-01

    Using an electron microscope's scanning transmission mode (STEM) for collection of tomographic datasets is advantageous compared to bright field transmission electron microscopic (TEM). For image formation, inelastic scattering does not cause chromatic aberration, since in STEM mode no image forming lenses are used after the beam has passed the sample, in contrast to regular TEM. Therefore, thicker samples can be imaged. It has been experimentally demonstrated that STEM is superior to TEM and energy filtered TEM for tomography of samples as thick as 1 μm. Even when using the best electron microscope, adequate sample preparation is the key for interpretable results. We adapted protocols for high-pressure freezing of cultivated cells from a physiological state. In this chapter, we describe optimized high-pressure freezing and freeze substitution protocols for STEM tomography in order to obtain high membrane contrast.

  15. Probing plasmons in three dimensions by combining complementary spectroscopies in a scanning transmission electron microscope

    DOE PAGES

    Hachtel, Jordan A.; Marvinney, Claire; Mouti, Anas; ...

    2016-03-02

    The nanoscale optical response of surface plasmons in three-dimensional metallic nanostructures plays an important role in many nanotechnology applications, where precise spatial and spectral characteristics of plasmonic elements control device performance. Electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) within a scanning transmission electron microscope have proven to be valuable tools for studying plasmonics at the nanoscale. Each technique has been used separately, producing three-dimensional reconstructions through tomography, often aided by simulations for complete characterization. Here we demonstrate that the complementary nature of the two techniques, namely that EELS probes beam-induced electronic excitations while CL probes radiative decay, allows usmore » to directly obtain a spatially- and spectrally-resolved picture of the plasmonic characteristics of nanostructures in three dimensions. Furthermore, the approach enables nanoparticle-by-nanoparticle plasmonic analysis in three dimensions to aid in the design of diverse nanoplasmonic applications.« less

  16. Probing plasmons in three dimensions by combining complementary spectroscopies in a scanning transmission electron microscope

    SciTech Connect

    Hachtel, Jordan A.; Marvinney, Claire; Mouti, Anas; Mayo, Daniel; Mu, Richard R.; Pennycook, Stephen J.; Lupini, Andrew R.; Chisholm, Matthew F.; Haglund, R. F.; Pantelides, Sokrates T.

    2016-03-02

    The nanoscale optical response of surface plasmons in three-dimensional metallic nanostructures plays an important role in many nanotechnology applications, where precise spatial and spectral characteristics of plasmonic elements control device performance. Electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) within a scanning transmission electron microscope have proven to be valuable tools for studying plasmonics at the nanoscale. Each technique has been used separately, producing three-dimensional reconstructions through tomography, often aided by simulations for complete characterization. Here we demonstrate that the complementary nature of the two techniques, namely that EELS probes beam-induced electronic excitations while CL probes radiative decay, allows us to directly obtain a spatially- and spectrally-resolved picture of the plasmonic characteristics of nanostructures in three dimensions. Furthermore, the approach enables nanoparticle-by-nanoparticle plasmonic analysis in three dimensions to aid in the design of diverse nanoplasmonic applications.

  17. New area detector for atomic-resolution scanning transmission electron microscopy.

    PubMed

    Shibata, Naoya; Kohno, Yuji; Findlay, Scott D; Sawada, Hidetaka; Kondo, Yukihito; Ikuhara, Yuichi

    2010-01-01

    A new area detector for atomic-resolution scanning transmission electron microscopy (STEM) is developed and tested. The circular detector is divided into 16 segments which are individually optically coupled with photomultiplier tubes. Thus, 16 atomic-resolution STEM images which are sensitive to the spatial distribution of scattered electrons on the detector plane can be simultaneously obtained. This new detector can be potentially used not only for the simultaneous formation of common bright-field, low-angle annular dark-field and high-angle annular dark-field images, but also for the quantification of images by detecting the full range of scattered electrons and even for exploring novel atomic-resolution imaging modes by post-processing combination of the individual images.

  18. Novel method of simultaneous multiple immunogold localization on resin sections in high resolution scanning electron microscopy.

    PubMed

    Nebesarova, Jana; Wandrol, Petr; Vancova, Marie

    2016-01-01

    We present a new method of multiple immunolabeling that is suitable for a broad spectrum of biomedical applications. The general concept is to label both sides of the ultrathin section with the thickness of 70-80 nm with different antibodies conjugated to gold nanoparticles and to distinguish the labeled side by advanced imaging methods with high resolution scanning electron microscopy, such as by correlating images acquired at different energies of primary electrons using different signals. From the Clinical Editor: The use of transmission electron microscopy has become an indispensible tool in the detection of cellular proteins. In this short but interesting article, the authors described their new method of labeling and the identification of four different proteins simultaneously, which represents another advance in imaging technique.

  19. Atomic scale characterization of semiconductor interfaces by scanning transmission electron microscopy

    SciTech Connect

    Pennycook, S.J.; Chisholm, M.F.; Duscher, G.; Maiti, A.; Pantelides, S.T.

    1997-05-01

    Recently, the scanning transmission electron microscope has become capable of forming electron probes of atomic dimensions. Through the technique of Z-contrast imaging, it is now possible to form atomic resolution images with high compositional sensitivity from which atomic column positions can be directly determined. An incoherent image of this nature also allows atomic resolution chemical analysis to be performed, by locating the probe over particular columns or planes seen in the image while electron energy loss spectra are collected. These powerful techniques, combined with atomic-scale calculations, constitute a powerful probe of the structural, kinetic and thermodynamic properties of complex materials. The authors show the direct observation of As segregated to specific sites in a Si grain boundary, and present a candidate model for the structure of the Si/SiO{sub 2} interface.

  20. Investigation of magnetic domains in Ni Mn Ga alloys with a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Ge, Y.; Heczko, O.; Söderberg, O.; Hannula, S.-P.; Lindroos, V. K.

    2005-10-01

    The magnetic domains of martensite have been investigated with a scanning electron microscope in three Ni-Mn-Ga alloys with five-layered, seven-layered and non-layered (T) martensite structure. Type I magnetic contrast provides an overview of the domain pattern. This contrast arises from the stray field of the specimen and it is observed in a secondary-electron image. The type II magnetic contrast of a backscattered electron image gives the detailed magnetic microstructure together with the crystal morphology. A stripe domain pattern is formed in all the alloys when there is one dominant martensite variant in the sample. The second minor variant might be distorted due to interaction with the magnetic domain structure of the major variant. The mechanism of the deformation is not entirely clear and a tentative explanation for this deformation is suggested.

  1. Precession electron diffraction in scanning transmission electron microscopy: phase, orientation and strain mapping at the nanometer scale

    NASA Astrophysics Data System (ADS)

    Sharp, T. G.

    2015-12-01

    Precession electron diffraction is a technique used in scanning transmission electron microscopy (STEM) to collect electron diffraction patterns while precessing the beam in a cone around the optic axis of the microscope. Electrons are strongly scattered by matter, resulting in dynamical diffraction effects and complex intensity distributions. Precession diffraction produces patterns that are nearly kinematical and lack the complicated intensity distributions of dynamical scattering. These patterns are readily indexed by computer, which allows for the structural characterization of the sample at each pixel. This technique is analogous to electron backscatter diffraction (EBSD), but with higher spatial resolution. Like EBSD, precession diffraction is used to make phase and orientation maps in polycrystalline aggregates and deformed crystals. The technique also provides quantitative strain mapping at the nanometer scale for characterization of defects and coherent interfaces. This technique is especially useful for characterizing nano-scale intergrowths that are produced in high-pressure experiments and in naturally shocked samples. We are using this technique on our aberration corrects JEOL ARM200F STEM. Examples of experimentally and naturally transformed olivine will be presented.

  2. Using the Scanning Electron Microscope to Study Tracks in CR-39

    NASA Astrophysics Data System (ADS)

    Sullivan, Kyle; Roberts, Samuel; McLean, James; Padalino, Steve

    2002-10-01

    CR-39 is a plastic used for high-energy charged particle detection. When particles hit the detector, they create tracks. These tracks can be enlarged with wet-chemical etching, and are useful in determining the energy and type of incident particle. To understand the etching process beyond the capabilities of an optical microscope, a scanning electron microscope investigation was undertaken. Preparation of a CR-39 sample involved exposing it to 5.5 MeV alpha particles, etching it in 6M NaOH at 80 degrees Celsius, and applying a thin conductive layer of gold-palladium. Three main areas of study were focused upon. It was found that the diameters of tracks increased linearly as a function of how long the samples were etched. A depth profile of a track was constructed by using the parallax that occurs between normal and tilted views. Techniques for scanning an entire sample were compared to optical methods used at the Laboratory for Laser Energetics. Although higher image quality can be achieved, factors, such as total scan time, decreased its appeal as a new way to scan CR-39. Research funded in part by the United States Department of Energy

  3. 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.

  4. Two-stage gas amplifier for ultrahigh resolution low vacuum scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Thiel, B. L.; Toth, M.; Schroemges, R. P. M.; Scholtz, J. J.; van Veen, G.; Knowles, W. R.

    2006-03-01

    We describe a magnetic field assisted, two-stage secondary electron gas amplification process for low vacuum scanning electron microscopy. The field of an ultrahigh resolution magnetic immersion objective lens and the electric field of an annular electrode configuration partition the amplification volume into two regions in which the electric and magnetic fields are parallel and crossed, respectively. The fields confine secondary electrons to axial and radial oscillations within the detector volume, until all of the kinetic energy imparted by an anode is dissipated through inelastic collisions with gas molecules. The electron confinement yields high gas amplification efficiency at short working distances and low gas pressures, facilitating high resolution imaging at low electron beam energies. Charging of insulating specimens is stabilized by positive ions produced in the gas ionization cascade. Furthermore, the signal to background level and bandwidth of this detector are superior to those of earlier generations of environmental secondary electron detectors. The combination of low vacuum, short working distance, and low beam energy is attractive to the semiconductor metrology industry, in particular, for critical dimension measurements on photolithographic masks.

  5. Two-stage gas amplifier for ultrahigh resolution low vacuum scanning electron microscopy

    SciTech Connect

    Thiel, B.L.; Toth, M.; Schroemges, R.P.M.; Scholtz, J.J.; Veen, G. van; Knowles, W.R.

    2006-03-15

    We describe a magnetic field assisted, two-stage secondary electron gas amplification process for low vacuum scanning electron microscopy. The field of an ultrahigh resolution magnetic immersion objective lens and the electric field of an annular electrode configuration partition the amplification volume into two regions in which the electric and magnetic fields are parallel and crossed, respectively. The fields confine secondary electrons to axial and radial oscillations within the detector volume, until all of the kinetic energy imparted by an anode is dissipated through inelastic collisions with gas molecules. The electron confinement yields high gas amplification efficiency at short working distances and low gas pressures, facilitating high resolution imaging at low electron beam energies. Charging of insulating specimens is stabilized by positive ions produced in the gas ionization cascade. Furthermore, the signal to background level and bandwidth of this detector are superior to those of earlier generations of environmental secondary electron detectors. The combination of low vacuum, short working distance, and low beam energy is attractive to the semiconductor metrology industry, in particular, for critical dimension measurements on photolithographic masks.

  6. Charging/discharge events in coated spacecraft polymers during electron beam irradiation in a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Czeremuszkin, G.; Latrèche, M.; Wertheimer, M. R.

    2001-12-01

    Spacecraft, such as those operating in geosynchronous orbit (GEO), can be subjected to intense irradiation by charged particles, for example high-energy (e.g. 20 keV) electrons. The surfaces of dielectric materials (for example, polymers used as "thermal blankets") can therefore become potential sites for damaging electrostatic discharge (ESD) pulse events. We simulate these conditions by examining small specimens of three relevant polymers (polyimide, polyester and fluoropolymer), both bare and coated, in a scanning electron microscope (SEM). The coatings examined include commercial indium-tin oxide (ITO), and thin films of SiO 2 and a-Si:H deposited by plasma-enhanced chemical vapor deposition (PECVD). All coatings are found to greatly modify the observed ESD behavior, compared with that of the bare polymer counterparts. These observations are explained in terms of the model for ESD pulses proposed by Frederickson.

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

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  8. Scanning Tunneling Microscopy Study of Atomic and Electronic Structures of PbTaSe2

    NASA Astrophysics Data System (ADS)

    Chuang, Tien-Ming; Guan, Syu-You; Chen, Peng-Jen; Chang, Tay-Rong; Sankar, Raman; Chou, Fang-Cheng; Jeng, Horng-Tay; Chang, Chia-Seng

    The non-centrosymmetric PbTaSe2 becomes superconducting at Tc = 3.7K and is proposed to have a 3D massive Dirac fermions by large spin orbital coupling. The observation of topological nodal line states has been reported by recent ARPES measurements, making this material a great candidate to investigate the coupling between topological states and superconductivity. Here we conduct detail studies on cleaved PbTaSe2 surfaces by spectroscopic imaging-scanning tunneling microscope. Our results reveal several types of cleaved surfaces, within which each exhibits distinct different LDOS from scanning tunneling spectroscopy measurements. We identify different surface terminations from their atomic structures and their corresponding electronic properties both above and below Tc. We will report the impact on superconducting properties of different surfaces, and also discuss the relation between the surface state and superconductivity.

  9. Combined scanning transmission X-ray and electron microscopy for the characterization of bacterial endospores.

    PubMed

    Jamroskovic, Jan; Shao, Paul P; Suvorova, Elena; Barak, Imrich; Bernier-Latmani, Rizlan

    2014-09-01

    Endospores (also referred to as bacterial spores) are bacterial structures formed by several bacterial species of the phylum Firmicutes. Spores form as a response to environmental stress. These structures exhibit remarkable resistance to harsh environmental conditions such as exposure to heat, desiccation, and chemical oxidants. The spores include several layers of protein and peptidoglycan that surround a core harboring DNA as well as high concentrations of calcium and dipicolinic acid (DPA). A combination of scanning transmission X-ray microscopy, scanning transmission electron microscopy, and energy dispersive spectroscopy was used for the direct quantitative characterization of bacterial spores. The concentration and localization of DPA, Ca(2+) , and other elements were determined and compared for the core and cortex of spores from two distinct genera: Bacillus subtilis and Desulfotomaculum reducens. This micro-spectroscopic approach is uniquely suited for the direct study of individual bacterial spores, while classical molecular and biochemical methods access only bulk characteristics.

  10. Rapid imaging of mycoplasma in solution using Atmospheric Scanning Electron Microscopy (ASEM)

    SciTech Connect

    Sato, Chikara; Manaka, Sachie; Nakane, Daisuke; Nishiyama, Hidetoshi; Suga, Mitsuo; Nishizaka, Takayuki; Miyata, Makoto; Maruyama, Yuusuke

    2012-01-27

    Highlights: Black-Right-Pointing-Pointer Mycoplasma mobile was observed in buffer with the Atmospheric Scanning Electron Microscope. Black-Right-Pointing-Pointer Characteristic protein localizations were visualized using immuno-labeling. Black-Right-Pointing-Pointer M. mobile attached to sialic acid on the SiN film surface within minutes. Black-Right-Pointing-Pointer Cells were observed at low concentrations. Black-Right-Pointing-Pointer ASEM should promote study and early-stage diagnosis of mycoplasma. -- Abstract: Mycoplasma is a genus of bacterial pathogen that causes disease in vertebrates. In humans, the species Mycoplasma pneumoniae causes 15% or more of community-acquired pneumonia. Because this bacterium is tiny, corresponding in size to a large virus, diagnosis using optical microscopy is not easy. In current methods, chest X-rays are usually the first action, followed by serology, PCR amplification, and/or culture, but all of these are particularly difficult at an early stage of the disease. Using Mycoplasma mobile as a model species, we directly observed mycoplasma in buffer with the newly developed Atmospheric Scanning Electron Microscope (ASEM). This microscope features an open sample dish with a pressure-resistant thin film window in its base, through which the SEM beam scans samples in solution, from below. Because of its 2-3 {mu}m-deep scanning capability, it can observe the whole internal structure of mycoplasma cells stained with metal solutions. Characteristic protein localizations were visualized using immuno-labeling. Cells were observed at low concentrations, because suspended cells concentrate in the observable zone by attaching to sialic acid on the silicon nitride (SiN) film surface within minutes. These results suggest the applicability of the ASEM for the study of mycoplasmas as well as for early-stage mycoplasma infection diagnosis.

  11. Large-scale Scanning Transmission Electron Microscopy (Nanotomy) of Healthy and Injured Zebrafish Brain

    PubMed Central

    Kuipers, Jeroen; Kalicharan, Ruby D.; Wolters, Anouk H. G.

    2016-01-01

    Large-scale 2D electron microscopy (EM), or nanotomy, is the tissue-wide application of nanoscale resolution electron microscopy. Others and we previously applied large scale EM to human skin pancreatic islets, tissue culture and whole zebrafish larvae1-7. Here we describe a universally applicable method for tissue-scale scanning EM for unbiased detection of sub-cellular and molecular features. Nanotomy was applied to investigate the healthy and a neurodegenerative zebrafish brain. Our method is based on standardized EM sample preparation protocols: Fixation with glutaraldehyde and osmium, followed by epoxy-resin embedding, ultrathin sectioning and mounting of ultrathin-sections on one-hole grids, followed by post staining with uranyl and lead. Large-scale 2D EM mosaic images are acquired using a scanning EM connected to an external large area scan generator using scanning transmission EM (STEM). Large scale EM images are typically ~ 5 - 50 G pixels in size, and best viewed using zoomable HTML files, which can be opened in any web browser, similar to online geographical HTML maps. This method can be applied to (human) tissue, cross sections of whole animals as well as tissue culture1-5. Here, zebrafish brains were analyzed in a non-invasive neuronal ablation model. We visualize within a single dataset tissue, cellular and subcellular changes which can be quantified in various cell types including neurons and microglia, the brain's macrophages. In addition, nanotomy facilitates the correlation of EM with light microscopy (CLEM)8 on the same tissue, as large surface areas previously imaged using fluorescent microscopy, can subsequently be subjected to large area EM, resulting in the nano-anatomy (nanotomy) of tissues. In all, nanotomy allows unbiased detection of features at EM level in a tissue-wide quantifiable manner. PMID:27285162

  12. Large-scale Scanning Transmission Electron Microscopy (Nanotomy) of Healthy and Injured Zebrafish Brain.

    PubMed

    Kuipers, Jeroen; Kalicharan, Ruby D; Wolters, Anouk H G; van Ham, Tjakko J; Giepmans, Ben N G

    2016-05-25

    Large-scale 2D electron microscopy (EM), or nanotomy, is the tissue-wide application of nanoscale resolution electron microscopy. Others and we previously applied large scale EM to human skin pancreatic islets, tissue culture and whole zebrafish larvae(1-7). Here we describe a universally applicable method for tissue-scale scanning EM for unbiased detection of sub-cellular and molecular features. Nanotomy was applied to investigate the healthy and a neurodegenerative zebrafish brain. Our method is based on standardized EM sample preparation protocols: Fixation with glutaraldehyde and osmium, followed by epoxy-resin embedding, ultrathin sectioning and mounting of ultrathin-sections on one-hole grids, followed by post staining with uranyl and lead. Large-scale 2D EM mosaic images are acquired using a scanning EM connected to an external large area scan generator using scanning transmission EM (STEM). Large scale EM images are typically ~ 5 - 50 G pixels in size, and best viewed using zoomable HTML files, which can be opened in any web browser, similar to online geographical HTML maps. This method can be applied to (human) tissue, cross sections of whole animals as well as tissue culture(1-5). Here, zebrafish brains were analyzed in a non-invasive neuronal ablation model. We visualize within a single dataset tissue, cellular and subcellular changes which can be quantified in various cell types including neurons and microglia, the brain's macrophages. In addition, nanotomy facilitates the correlation of EM with light microscopy (CLEM)(8) on the same tissue, as large surface areas previously imaged using fluorescent microscopy, can subsequently be subjected to large area EM, resulting in the nano-anatomy (nanotomy) of tissues. In all, nanotomy allows unbiased detection of features at EM level in a tissue-wide quantifiable manner.

  13. Scanning electron microscopy study of adhesion in sea urchin blastulae. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Crowther, Susan D.

    1988-01-01

    The dissociation supernatant (DS) isolated by disaggregating Strongylocentrotus purpuratus blastulae in calcium- and magnesium-free seawater specifically promotes reaggregation of S. purpuratus blastula cells. The purpose of this study was to use scanning electron microscopy to examine the gross morphology of aggregates formed in the presence of DS to see if it resembles adhesion in partially dissociated blastulae. A new reaggregation procedure developed here, using large volumes of cell suspension and a large diameter of rotation, was utilized to obtain sufficient quantities of aggregates for scanning electron microscopy. The results indicate that aggregates formed in the presence of DS resemble partially dissociated intact embryos in terms of the direct cell-cell adhesion observed. DS did not cause aggregation to form as a result of the entrapment of cells in masses of extracellular material. These studies provide the groundwork for further studies using transmission electron microscopy to more precisely define the adhesive contacts made by cells in the presence of the putative adhesion molecules present in DS.

  14. Scanning photoelectron microscope for nanoscale three-dimensional spatial-resolved electron spectroscopy for chemical analysis

    NASA Astrophysics Data System (ADS)

    Horiba, K.; Nakamura, Y.; Nagamura, N.; Toyoda, S.; Kumigashira, H.; Oshima, M.; Amemiya, K.; Senba, Y.; Ohashi, H.

    2011-11-01

    In order to achieve nondestructive observation of the three-dimensional spatially resolved electronic structure of solids, we have developed a scanning photoelectron microscope system with the capability of depth profiling in electron spectroscopy for chemical analysis (ESCA). We call this system 3D nano-ESCA. For focusing the x-ray, a Fresnel zone plate with a diameter of 200 μm and an outermost zone width of 35 nm is used. In order to obtain the angular dependence of the photoelectron spectra for the depth-profile analysis without rotating the sample, we adopted a modified VG Scienta R3000 analyzer with an acceptance angle of 60° as a high-resolution angle-resolved electron spectrometer. The system has been installed at the University-of-Tokyo Materials Science Outstation beamline, BL07LSU, at SPring-8. From the results of the line-scan profiles of the poly-Si/high-k gate patterns, we achieved a total spatial resolution better than 70 nm. The capability of our system for pinpoint depth-profile analysis and high-resolution chemical state analysis is demonstrated.

  15. Scanning photoelectron microscope for nanoscale three-dimensional spatial-resolved electron spectroscopy for chemical analysis

    SciTech Connect

    Horiba, K.; Oshima, M.; Nakamura, Y.; Nagamura, N.; Toyoda, S.; Kumigashira, H.; Amemiya, K.; Senba, Y.; Ohashi, H.

    2011-11-15

    In order to achieve nondestructive observation of the three-dimensional spatially resolved electronic structure of solids, we have developed a scanning photoelectron microscope system with the capability of depth profiling in electron spectroscopy for chemical analysis (ESCA). We call this system 3D nano-ESCA. For focusing the x-ray, a Fresnel zone plate with a diameter of 200 {mu}m and an outermost zone width of 35 nm is used. In order to obtain the angular dependence of the photoelectron spectra for the depth-profile analysis without rotating the sample, we adopted a modified VG Scienta R3000 analyzer with an acceptance angle of 60 deg. as a high-resolution angle-resolved electron spectrometer. The system has been installed at the University-of-Tokyo Materials Science Outstation beamline, BL07LSU, at SPring-8. From the results of the line-scan profiles of the poly-Si/high-k gate patterns, we achieved a total spatial resolution better than 70 nm. The capability of our system for pinpoint depth-profile analysis and high-resolution chemical state analysis is demonstrated.

  16. Three-dimensional architecture of podocytes revealed by block-face scanning electron microscopy

    PubMed Central

    Ichimura, Koichiro; Miyazaki, Naoyuki; Sadayama, Shoji; Murata, Kazuyoshi; Koike, Masato; Nakamura, Kei-ichiro; Ohta, Keisuke; Sakai, Tatsuo

    2015-01-01

    Block-face imaging is a scanning electron microscopic technique which enables easier acquisition of serial ultrastructural images directly from the surface of resin-embedded biological samples with a similar quality to transmission electron micrographs. In the present study, we analyzed the three-dimensional architecture of podocytes using serial block-face imaging. It was previously believed that podocytes are divided into three kinds of subcellular compartment: cell body, primary process, and foot process, which are simply aligned in this order. When the reconstructed podocytes were viewed from their basal side, the foot processes were branched from a ridge-like prominence, which was formed on the basal surface of the primary process and was similar to the usual foot processes in structure. Moreover, from the cell body, the foot processes were also emerged via the ridge-like prominence, as found in the primary process. The ridge-like prominence anchored the cell body and primary process to the glomerular basement membrane, and connected the foot processes to the cell body and primary process. In conclusion, serial block-face imaging is a powerful tool for clear understanding the three-dimensional architecture of podocytes through its ability to reveal novel structures which were difficult to determine by conventional transmission and scanning electron microscopes alone. PMID:25759085

  17. Gold nanoparticle uptake in whole cells in liquid examined by environmental scanning electron microscopy.

    PubMed

    Peckys, Diana B; de Jonge, Niels

    2014-02-01

    The size of gold nanoparticles (AuNPs) can influence various aspects of their cellular uptake. Light microscopy is not capable of resolving most AuNPs, while electron microscopy (EM) is not practically capable of acquiring the necessary statistical data from many cells and the results may suffer from various artifacts. Here, we demonstrate the use of a fast EM method for obtaining high-resolution data from a much larger population of cells than is usually feasible with conventional EM. A549 (human lung carcinoma) cells were subjected to uptake protocols with 10, 15, or 30 nm diameter AuNPs with adsorbed serum proteins. After 20 min, 24 h, or 45 h, the cells were fixed and imaged in whole in a thin layer of liquid water with environmental scanning electron microscopy equipped with a scanning transmission electron microscopy detector. The fast preparation and imaging of 145 whole cells in liquid allowed collection of nanoscale data within an exceptionally small amount of time of ~80 h. Analysis of 1,041 AuNP-filled vesicles showed that the long-term AuNP storing lysosomes increased their average size by 80 nm when AuNPs with 30 nm diameter were uptaken, compared to lysosomes of cells incubated with AuNPs of 10 and 15 nm diameter.

  18. Scanning and transmission electron microscopic analysis of ampullary segment of oviduct during estrous cycle in caprines.

    PubMed

    Sharma, R K; Singh, R; Bhardwaj, J K

    2015-01-01

    The ampullary segment of the mammalian oviduct provides suitable milieu for fertilization and development of zygote before implantation into uterus. It is, therefore, in the present study, the cyclic changes in the morphology of ampullary segment of goat oviduct were studied during follicular and luteal phases using scanning and transmission electron microscopy techniques. Topographical analysis revealed the presence of uniformly ciliated ampullary epithelia, concealing apical processes of non-ciliated cells along with bulbous secretory cells during follicular phase. The luteal phase was marked with decline in number of ciliated cells with increased occurrence of secretory cells. The ultrastructure analysis has demonstrated the presence of indented nuclear membrane, supranuclear cytoplasm, secretory granules, rough endoplasmic reticulum, large lipid droplets, apically located glycogen masses, oval shaped mitochondria in the secretory cells. The ciliated cells were characterized by the presence of elongated nuclei, abundant smooth endoplasmic reticulum, oval or spherical shaped mitochondria with crecentric cristae during follicular phase. However, in the luteal phase, secretory cells were possessing highly indented nucleus with diffused electron dense chromatin, hyaline nucleosol, increased number of lipid droplets. The ciliated cells had numerous fibrous granules and basal bodies. The parallel use of scanning and transmission electron microscopy techniques has enabled us to examine the cyclic and hormone dependent changes occurring in the topography and fine structure of epithelium of ampullary segment and its cells during different reproductive phases that will be great help in understanding major bottle neck that limits success rate in vitro fertilization and embryo transfer technology.

  19. A new method of scanning electron microscopy for imaging biological tissues.

    PubMed

    Boyde, A; Reid, S A

    1983-04-07

    The scanning electron microscope (SEM) has proved of little value in the examination of material prepared for light microscopic histology. One of the chief reasons for this is that the secondary electron signal used for image formation in routine scanning microscopy derives from the surface of the specimen. In the case of histological material this surface is one which has been severely distorted by processing and cutting procedures. Light microscopy sections can be usefully studied in te SEM if the signal used to form the image derives from a considerable portion of the thickness of the section. Thus the backscattered electron (BSE) image has been successfully used in studying the distribution of dense material or densely staining components several micrometres deep to the surface of dried sections. Such sections are, however, usually mounted on low density (poorly BSE reflecting) non-transparent substrates such as beryllium or carbon, so that matching light microscopy of the same samples is not possible. We report here a method by which histological sections mounted on glass slides can be imaged in the SEM at a resolution higher than that obtained using conventional light microscopy. The method exploits the facts that the ordinary, cheap light microscope slide is strongly cathodoluminescent, yet the standard histological (7 micrometers) section is of such a mass thickness that it absorbs a significant proportion of electrons which energies (5-20 keV) usually used in biological SEM. Thus the measure of the glass cathodoluminescence signal is the measure of the electron flux passing through the specimen.

  20. Subsurface Examination of a Foliar Biofilm Using Scanning Electron- and Focused-Ion-Beam Microscopy

    SciTech Connect

    Wallace, Patricia K.; Arey, Bruce W.; Mahaffee, Walt F.

    2011-08-01

    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 can remove a predetermined amount of material from a selected site to allow for subsurface exploration and when coupled with SEM or scanning ion- beam microscopy (SIM) could be suitable to examine the subsurface structure of bacterial biofilms on the leaf surface. The suitability of chemical and cryofixation was examined for use with the FIB SEM to examine bacterial biofilms on leaf surfaces. The biological control agent, Burkholderia pyroccinia FP62, that rapidly colonizes the leaf surface and forms biofilms, was inoculated onto geranium leaves and incubated in a greenhouse for 7 or 14 days. Cryofixation was not suitable for examination of leaf biofilms because it created a frozen layer over the leaf surface that cracked when exposed to the electron beam and the protective cap required for FIB milling could not be accurately deposited. With chemically fixed samples, it was possible to precisely FIB mill a single cross section (5 µm) or sequential cross sections from a single site without any damage to the surrounding surface. Biofilms, 7 days post-inoculation (DPI), were composed of 2 to 5 bacterial cell layers while biofilms 14 DPI ranged from 5 to greater than 30 cell layers. Empty spaces between bacteria cells in the subsurface structure were observed in biofilms 7- and 14-DPI. Sequential cross sections inferred that the empty spaces were often continuous between FP62 cells and could possibly make up a network of channels throughout the biofilm. FIB SEM was a useful tool to observe the subsurface composition of a foliar biofilm.

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

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  2. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2017-01-01

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

  4. Scanning electron microscopy and energy dispersive analysis: applications in the field of cultural heritage.

    PubMed

    Schreiner, Manfred; Melcher, Michael; Uhlir, Katharina

    2007-02-01

    Scanning electron microscopy has been extensively used for the material characterization of objects of artistic and archaeological importance, especially in combination with energy dispersive X-ray microanalysis (SEM/EDX). The advantages and limitations of SEM/EDX are presented in a few case studies: analysis of pigments in cross-sections of paint layers, quantitative analysis of archaeological glass from the Roman period excavated in Ephesos/Turkey, and investigations on glasses with medieval composition concerning their weathering stability and degradation phenomena.

  5. In situ scanning electron microscopy of graphene growth on polycrystalline Ni substrate

    NASA Astrophysics Data System (ADS)

    Takahashi, Katsuhiro; Yamada, Kazuki; Kato, Hiroki; Hibino, Hiroki; Homma, Yoshikazu

    2012-04-01

    Scanning electron microscopy (SEM) is shown to be capable of imaging a monolayer of graphene, and is employed to observe in situ the graphene growth process by segregation of bulk-dissolved carbon on a polycrystalline nickel surface. Because of a wide field of view, SEM could easily track the rapid graphene growth induced by carbon segregation. Monolayer graphene extended on (111)- and (011)-oriented nickel grains, but was excluded from the (001) grains. This is due to the difference in carbon-nickel binding energy among these crystalline faces. This work proves the usefulness of in situ SEM imaging for the investigation of large area graphene growth.

  6. Microstructure development in particulate coatings examined with high-resolution cryogenic scanning electron microscopy

    SciTech Connect

    Sheehan, J.G.; Davis, H.T.; Scriven, L.E.; Takamura, Koichi

    1993-12-01

    The authors used cryogenic scanning electron microscopy to examine the early stages of latex film formation. They visualized the influence of ionic strength and extent of carboxylation in latex-calcium carbonate formulations and in latex-only formulations. Results demonstrated that latex particles deposited on calcium carbonate surfaces creating a suspension of carboxylic acid-stabilized calcium carbonate particles. Images of consolidation fronts showed that variation of ionic strength and extent of carboxylation dramatically changes the way latex particles consolidate and form films.

  7. Study of environmental biodegradation of LDPE films in soil using optical and scanning electron microscopy.

    PubMed

    Mumtaz, Tabassum; Khan, M R; Hassan, Mohd Ali

    2010-07-01

    An outdoor soil burial test was carried out to evaluate the degradation of commercially available LDPE carrier bags in natural soil for up to 2 years. Biodegradability of low density polyethylene films in soil was monitored using both optical and scanning electron microscopy (SEM). After 7-9 months of soil exposure, microbial colonization was evident on the film surface. Exposed LDPE samples exhibit progressive changes towards degradation after 17-22 months. SEM images reveal signs of degradation such as exfoliation and formation of cracks on film leading to disintegration. The possible degradation mode and consequences on the use and disposal of LDPE films is discussed.

  8. Scanning electron microscopy and energy dispersive analysis of machined denture base surfaces.

    PubMed

    Radford, D R; Walter, J D; Challacombe, S J

    1997-01-01

    To relate the characteristics of rotary instruments to the surfaces they produce, acrylic resin, Molloplast B, and Novus were investigated with energy dispersive analysis and scanning electron microscopy (secondary and backscatter images) before and after machining. The chemical composition of cutting instruments, material surfaces, and residues was identified. Machined debris embedded in Molloplast B after machining with the Molloplast stone was found to contain a mean lead content of 45%. High concentrations of barium sulphate were discovered on the arbor band-machined surface of Novus. These differences were related to clinically appropriate instrumentation, and, therefore, biocompatibility studies that intimately relate to the in vivo situation should be considered for new materials.

  9. Silica granuloma: scanning electron microscopy and energy dispersive X-ray microanalysis.

    PubMed

    Chun, S I; Cho, S W

    1991-02-01

    A 46-year-old woman had 1-month-old erythematous papules on the left elbow and both knees where acupuncture with gold needles had been performed twenty years earlier. She also had a 2-month-old pruritic scar lesion on the nape. Histopathologic findings showed sarcoidal granulomas. The presence of silica components in the granulomas was confirmed by scanning electron microscopy (SEM) of the lesion on the nape and energy dispersive X-ray microanalysis (EDXA) of the lesions on the nape and the left elbow. We suggest that acupuncture with gold needles may be one cause of silica granuloma.

  10. A scanning electron microscopic evaluation of different root canal irrigation regimens.

    PubMed

    Mônika, Chaves Medici; Fröner, Izabel Cristina

    2006-01-01

    The purpose of this study was to assess the effectiveness of endodontic irrigants in removing the smear layer from instrumented root canal walls using Scanning Electron Microscopy (SEM). The endodontic irrigants used were: 1% sodium hypochlorite (NaOCl); 1% NaOCl mixed to 17% EDTAC; 2% chlorhexidine gel; and Ricinus communis gel. Photomicrographs of the middle and apical thirds were evaluated with the aid of the Fotoscore - v. 2.0 software. The results indicated that the mixture of sodium hypochlorite and EDTAC completely removed the smear layer from dentinal walls. The other endodontic irrigants were not as efficient in cleansing the root canals.

  11. Scanning electron microscopy of scales and its taxonomic application in the fish genus Channa.

    PubMed

    Dey, Sudip; Biswas, Shyama P; Dey, Samujjwal; Bhattacharyya, Shankar P

    2014-08-01

    Scanning electron microscopy (SEM) of scales in six species of the fish genus Channa revealed certain features relevant to taxonomic significance. The location of focus, inter-radial distance and width of circuli, inter-circular space, width of radii, shape and size of lepidonts, etc. were found to be different in different species. The importance of SEM of scales in poorly understood taxonomy and phylogeny of the fish genus Channa is discussed with the help of relevant literature. Further, the role of SEM of fish scales for taxonomic applications is discussed in detail.

  12. Phase aligner for the Electronically Scanned Thinned Array Radiometer (ESTAR) instrument

    NASA Technical Reports Server (NTRS)

    Chren, William A., Jr.; Zomberg, Brian G.

    1993-01-01

    A prototype Phase Aligner (PA) or the Electronically Scanned Thinned Array Radiometer instrument has been designed and tested. Implemented in a single Xilinx XC3042PC84-125 Field Programmable Gate Array (FPGA), it is a dual-port register file which allows independent storage and phase coherent retrieval of antenna array data by the Central Processing Unit (CPU). It has dimensions of 4 x 20 bits and can be used at clock frequencies as high as 25 MHz. The ESTAR is a passive synthetic-aperture radiometer designed to sense soil moisture and ocean salinity at L-band.

  13. Walsh function generator for the Electronically Scanned Thinned Array Radiometer (ESTAR) instrument

    NASA Technical Reports Server (NTRS)

    Chren, William A., Jr.

    1993-01-01

    A prototype Walsh Function Generator (WFG) for the ESTAR (Electronically Scanned Thinned Array Radiometer) instrument has been designed and tested. Implemented in a single Xilinx XC3020PC68-50 Field Programmable Gate Array (FPGA), it generates a user-programmable set of 32 consecutive Walsh Functions for noise cancellation in the analog circuitry of the Front-End Modules (FEM's). It is implemented in a 68-pin plastic leaded chip carrier (PLCC) package, is fully testable, and can be used for noise cancellation periods as small as 2 msec.

  14. Liquid scanning transmission electron microscopy: Nanoscale imaging in micrometers-thick liquids

    NASA Astrophysics Data System (ADS)

    Schuh, Tobias; de Jonge, Niels

    2014-02-01

    Scanning transmission electron microscopy (STEM) of specimens in liquid is possible using a microfluidic chamber with thin silicon nitride windows. This paper includes an analytic equation of the resolution as a function of the sample thickness and the vertical position of an object in the liquid. The equipment for STEM of liquid specimen is briefly described. STEM provides nanometer resolution in micrometer-thick liquid layers with relevance for both biological research and materials science. Using this technique, we investigated tagged proteins in whole eukaryotic cells, and gold nanoparticles in liquid with time-lapse image series. Possibly future applications are discussed. xml:lang="fr"

  15. Lanthanum Deposition in the Stomach: Usefulness of Scanning Electron Microscopy for Its Detection.

    PubMed

    Iwamuro, Masaya; Urata, Haruo; Tanaka, Takehiro; Ando, Akemi; Nada, Takahiro; Kimura, Kosuke; Yamauchi, Kenji; Kusumoto, Chiaki; Otsuka, Fumio; Okada, Hiroyuki

    2017-02-01

    After having been treated with lanthanum carbonate administration for 4 years for hyperphosphatemia, a 75-year-old Japanese woman undergoing hemodialysis was diagnosed with lanthanum phosphate deposition in the stomach. The deposition, seen as white microgranules, was observed using esophagogastroduodenoscopy with magnifying observation. To the best of our knowledge, these are the minutest endoscopy images of lanthanum phosphate deposition in the gastric mucosa. Scanning electron microscopy (SEM) observation enabled easier identification of the deposited material, which was visible as bright areas. The present case suggests the usefulness of SEM observation in the detection of lanthanum phosphate deposition in the gastrointestinal tract.

  16. Scanning-electron-microscope study of normal-impingement erosion of ductile metals

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Salik, J.

    1980-01-01

    Scanning electron microscopy was used to characterize the erosion of annealed copper and aluminum surfaces produced by both single- and multiple-particle impacts. Macroscopic 3.2 mm diameter steel balls and microscopic, brittle erodant particles were projected by a gas gun system so as to impact at normal incidence at speeds up to 140 m/sec. During the impacts by the brittle erodant particles, at lower speeds the erosion behavior was similar to that observed for the larger steel balls. At higher velocities, particle fragmentation and the subsequent cutting by the radial wash of debris created a marked change in the erosion mechanism.

  17. Carbon-fiber tips for scanning probe microscopes and molecular electronics experiments

    PubMed Central

    2012-01-01

    We fabricate and characterize carbon-fiber tips for their use in combined scanning tunneling and force microscopy based on piezoelectric quartz tuning fork force sensors. An electrochemical fabrication procedure to etch the tips is used to yield reproducible sub-100-nm apex. We also study electron transport through single-molecule junctions formed by a single octanethiol molecule bonded by the thiol anchoring group to a gold electrode and linked to a carbon tip by the methyl group. We observe the presence of conductance plateaus during the stretching of the molecular bridge, which is the signature of the formation of a molecular junction. PMID:22587692

  18. A low temperature scanning tunneling microscope for electronic and force spectroscopy.

    PubMed

    Smit, R H M; Grande, R; Lasanta, B; Riquelme, J J; Rubio-Bollinger, G; Agraït, N

    2007-11-01

    In this article, we describe and test a novel way to extend a low temperature scanning tunneling microscope with the capability to measure forces. The tuning fork that we use for this is optimized to have a high quality factor and frequency resolution. Moreover, as this technique is fully compatible with the use of bulk tips, it is possible to combine the force measurements with the use of superconductive or magnetic tips, advantageous for electronic spectroscopy. It also allows us to calibrate both the amplitude and the spring constant of the tuning fork easily, in situ and with high precision.

  19. Ti-6Al-4V electron beam weld qualification using laser scanning confocal microscopy

    SciTech Connect

    Wanjara, P. . E-mail: priti.wanjara@cnrc-nrc.gc.ca; Brochu, M.; Jahazi, M.

    2005-03-15

    Processing conditions for manufacturing Ti-6Al-4V components by welding using an electron beam source are known to influence the transformation microstructure in the narrow fusion and heat-affected zones of the weld region. This work examined the effect of multiple-sequence welding on the characteristics of the transformed beta microstructure, using laser scanning confocal microscopy to resolve the Widmanstaetten alpha-beta structure in the fusion zone. The evolution in the alpha interlamellar spacing and plate thickness with processing was then related to microhardness measurements in the weld region.

  20. Output data formatter for the Electronically Scanned Thinned Array Radiometer (ESTAR) instrument

    NASA Technical Reports Server (NTRS)

    Chren, William A., Jr.

    1993-01-01

    A prototype Output Data Formatter (ODF) for the ESTAR (Electronically Scanned Thinned Array Radiometer) instrument has been designed and tested. It employs programmable logic devices to format and tag correlator data for transmission to Earth. After accepting 170 bits or correlator and error data in parallel, it appends an identification word and then serially passes the data to the Small Explorer Data System (SEDS) for transmission at a maximum rate of greater than 15 Mb/sec. Implemented with two reprogrammable field programmable gate arrays (FPGA's), each contained in a 132-pin plastic pin grid array (PGA) package, the design is cascadeable, fully testable, and low-power.

  1. A practical method for the remote control of the scanning electron microscope.

    PubMed

    Yamada, Atsushi; Hirahara, Osamu; Tsuchida, Takayoshi; Sugano, Naoki; Date, Masaru

    2003-01-01

    We have developed a remote control system for the scanning electron microscope (SEM). It is called Web-SEM and can be accessed by anyone through the Web browser. It is not necessary to install special software to control the SEM. Because the operating performance changes with the amount of traffic on the Internet, we have connected the Web-SEM to a LAN/Internet in order to overcome this. We have checked the performance of the remote control operation and we were able to perform focus adjustment, stage movement, etc. over the Internet by improving the method of operation and image transfer.

  2. Visualizing gold nanoparticle uptake in live cells with liquid scanning transmission electron microscopy.

    PubMed

    Peckys, Diana B; de Jonge, Niels

    2011-04-13

    The intracellular uptake of 30 nm diameter gold nanoparticles (Au-NPs) was studied at the nanoscale in pristine eukaryotic cells. Live COS-7 cells were maintained in a microfluidic chamber and imaged using scanning transmission electron microscopy. A quantitative image analysis showed that Au-NPs bound to the membranes of vesicles, possibly lysosomes, and occupied 67% of the available surface area. The vesicles accumulated to form a micrometer-sized cluster after 24 h of incubation. Two clusters were analyzed and found to consist of 117 ± 9 and 164 ± 4 NP-filled vesicles.

  3. Filamentous phage pIV multimer visualized by scanning transmission electron microscopy

    SciTech Connect

    Linderoth, N.A.; Russel, M.; Simon, M.N.

    1997-11-28

    A family of homomultimeric outer-membrane proteins termed secretins mediates the secretion of large macromolecules such as enzymes and filamentous bacteriophages across bacterial outer membranes to the extracellular millieu. The secretin encoded by filamentous phage f1 was purified. Mass determination of individual molecules by scanning transmission electron microscopy revealed two forms, a unit multimer composed of about 14 subunits and a multimer dimer. The secretin is roughly cylindrical and has an internal diameter of about 80 angstroms, which is large enough to accommodate filamentous phage (diameter of 65 angstroms). 21 refs., 3 figs., 1 tab.

  4. Use of low-temperature scanning electron microscopy to observe icicles, ice fabric, rime and frost

    SciTech Connect

    Wergin, W.P.; Rango, A.; Erbe, E.F.

    1996-12-31

    Previous studies showed that low temperature scanning electron microscopy (SEM) can be used to record images of precipitated snow crystals, which collectively form structures that are commonly known as snowflakes. Information about the structure of snow crystals can be used to improve models that estimate the water equivalent of the winter snowpack. These models, which are based on satellite microwave data, have practical use in approximating the quantity of water that will be available for crop irrigation and hydroelectric power. Our previous success of using low temperature SEM to image snow crystals has encouraged us to utilize this technique for other types of frozen aqueous specimens.

  5. Scanning electron microscopy of a blister roof in dystrophic epidermolysis bullosa.

    PubMed

    Almeida, Hiram Larangeira de; Monteiro, Luciane; Marques e Silva, Ricardo; Rocha, Nara Moreira; Scheffer, Hans

    2013-01-01

    In dystrophic epidermolysis bullosa the genetic defect of anchoring fibrils leads to cleavage beneath the basement membrane, with its consequent loss. We performed scanning electron microscopy of an inverted blister roof of a case of dystrophic epidermolysis bullosa, confirmed by immunomapping and gene sequencing. With a magnification of 2000 times a net attached to the blister roof could be easily identified. This net was composed of intertwined flat fibers. With higher magnifications, different fiber sizes could be observed, some thin fibers measuring around 80 nm and thicker ones measuring between 200 and 300 nm.

  6. A low-cost technique to manufacture a container to process meiofauna for scanning electron microscopy.

    PubMed

    Abolafia, J

    2015-09-01

    An easy and low-cost method to elaborate a container to dehydrate nematodes and other meiofauna in order to process them for scanning electron microscopy (SEM) is presented. Illustrations of its elaboration, step by step, are included. In addition, a brief methodology to process meiofauna, especially nematodes and kinorhynchs, and illustrations are provided. With this methodology it is possible to easily introduce the specimens, to lock them in a closed chamber allowing the infiltration of fluids and gases (ethanol, acetone, carbon dioxide) but avoiding losing the specimens. After using this meiofauna basket for SEM the results are efficient. Examples of nematode and kinorhynch SEM pictures obtained using this methodology are also included.

  7. Reaction of LiD with water vapor: thermogravimetric and scanning electron microscopy studies

    SciTech Connect

    Balooch, M; Dinh, L N; LeMay, J D

    2000-09-14

    The kinetics of hydroxide film growth on LiD have been studied by the thermogravimetric method in nitrogen saturated with water vapor and by scanning electron microscopy (SEM) of samples that have been exposed to air with 50% relative humidity. The reaction probability is estimated to be 4 x 10{sup -7} for LiD exposed to ambient air with 50% relative humidity, suggesting that the diffusion through the hydroxide film is not the limiting step on the overall process at high moisture levels. The rate of growth is drastically reduced when the temperature is increased to 60 C.

  8. On the visibility of very thin specimens in annular bright field scanning transmission electron microscopy

    SciTech Connect

    Phillips, P. J.; Klie, R. F.

    2013-07-15

    Annular bright field (ABF) scanning transmission electron microscopy (STEM) is emerging as an important observation mode for its ability to simultaneously image both heavy and light elements. However, recent results have demonstrated that in the limit of a very thin specimen (a few atomic layers), the ABF and high angle annular dark field (HAADF) signals cease to be intuitively related: a phenomenon which is generally irrelevant when imaging 'normal' specimens. ABF/HAADF STEM observations and multislice image simulations of two catalyst samples of differing atomic weights are presented; it is shown that the nature of the ABF signal is specimen dependent.

  9. Three-dimensional structure of a parameatal urethral cyst by scanning electron microscopy.

    PubMed

    Yamada, Nanako; Yoshida, Yuichi; Ito, Ayako; Morino, Shinichi; Yamamoto, Osamu

    2013-05-01

    We report scanning electron microscopy (SEM) for a case of parameatal urethral cyst. A 6-year-old Japanese boy presented with a cyst on the right lateral side of the urethral meatus. Histological examination revealed a cyst lined with columnar epithelium. An immunohistochemical study showed positive staining for CK7, CK13, and CEA, and negative for CK20 in luminal cells. On SEM examination, the inner surface of the cyst showed ridges arranged in a gyrus-like manner at lower magnification. Higher magnification revealed luminal cells with short microvillus projections. Some cells showed apocrine, merocrine, and possibly holocrine-type secretions.

  10. [The results of scanning electron microscopy research on interdental stripping in vitro].

    PubMed

    Radlanski, R J; Jäger, A; Zimmer, B; Schwestka, R; Bertzbach, F

    1989-08-01

    In an in-vitro study the abrasive qualities of different orthodontic finishing strips were evaluated on the enamel surfaces of human teeth by means of a scanning electron microscope. As a result we can state that even the use of the finest finishing strip cannot eliminate the deep furrows that resulted from prior abrasion with a strip that is more coarse. The remaining furrows caused by the abrasive procedure are so deep and wide, that plaque accumulation may well be expected therein, and thus be predisposing for caries and periodontal pathology.

  11. Experimental evaluation of environmental scanning electron microscopes at high chamber pressure.

    PubMed

    Fitzek, H; Schroettner, H; Wagner, J; Hofer, F; Rattenberger, J

    2015-11-01

    In environmental scanning electron microscopy (ESEM) high pressure applications have become increasingly important. Wet or biological samples can be investigated without time-consuming sample preparation and potential artefacts from this preparation can be neglected. Unfortunately, the signal-to-noise ratio strongly decreases with increasing chamber pressure. To evaluate the high pressure performance of ESEM and to compare different electron microscopes, information about spatial resolution and detector type is not enough. On the one hand, the scattering of the primary electron beam increases, which vanishes the contrast in images; and on the other hand, the secondary electrons (SE) signal amplification decreases. The stagnation gas thickness (effective distance the beam has to travel through the imaging gas) as well as the SE detection system depend on the microscope and for a complete and serious evaluation of an ESEM or low vacuum SEM it is necessary to specify these two parameters. A method is presented to determine the fraction of scattered and unscattered electrons and to calculate the stagnation gas thickness (θ). To evaluate the high pressure performance of the SE detection system, a method is presented that allows for an analysis of a single image and the calculation of the signal-to-noise ratio of this image. All investigations are performed on an FEI ESEM Quanta 600 (field emission gun) and an FEI ESEM Quanta 200 (thermionic gun). These methods and measurements should represent opportunities for evaluating the high pressure performance of an ESEM.

  12. High-resolution imaging by scanning electron microscopy of semithin sections in correlation with light microscopy.

    PubMed

    Koga, Daisuke; Kusumi, Satoshi; Shodo, Ryusuke; Dan, Yukari; Ushiki, Tatsuo

    2015-12-01

    In this study, we introduce scanning electron microscopy (SEM) of semithin resin sections. In this technique, semithin sections were adhered on glass slides, stained with both uranyl acetate and lead citrate, and observed with a backscattered electron detector at a low accelerating voltage. As the specimens are stained in the same manner as conventional transmission electron microscopy (TEM), the contrast of SEM images of semithin sections was similar to TEM images of ultrathin sections. Using this technique, wide areas of semithin sections were also observed by SEM, without the obstruction of grids, which was inevitable for traditional TEM. This study also applied semithin section SEM to correlative light and electron microscopy. Correlative immunofluorescence microscopy and immune-SEM were performed in semithin sections of LR white resin-embedded specimens using a FluoroNanogold-labeled secondary antibody. Because LR white resin is hydrophilic and electron stable, this resin is suitable for immunostaining and SEM observation. Using correlative microscopy, the precise localization of the primary antibody was demonstrated by fluorescence microscopy and SEM. This method has great potential for studies examining the precise localization of molecules, including Golgi- and ER-associated proteins, in correlation with LM and SEM.

  13. Scanning tunneling microscopy characterization of the geometric and electronic structure of hydrogen-terminated silicon surfaces

    NASA Technical Reports Server (NTRS)

    Kaiser, W. J.; Bell, L. D.; Hecht, M. H.; Grunthaner, F. J.

    1988-01-01

    Scanning tunneling microscopy (STM) methods are used to characterize hydrogen-terminated Si surfaces prepared by a novel method. The surface preparation method is used to expose the Si-SiO2 interface. STM images directly reveal the topographic structure of the Si-SiO2 interface. The dependence of interface topography on oxide preparation conditions observed by STM is compared to the results of conventional surface characterization methods. Also, the electronic structure of the hydrogen-terminated surface is studied by STM spectroscopy. The near-ideal electronic structure of this surface enables direct tunnel spectroscopy measurements of Schottky barrier phenomena. In addition, this method enables probing of semiconductor subsurface properties by STM.

  14. A new method for measurement of the vitrification rate of earthenware texture by scanning electron microscope.

    PubMed

    Moon, Eun Jung; Kim, Su Kyeong; Han, Min Su; Lee, Eun Woo; Heo, Jun Su; Lee, Han Hyoung

    2013-08-01

    A new method for determining the vitrification rate of pottery depending on the firing temperature was devised using secondary electron images (SEI) of scanning electron microscope (SEM). Several tests were performed to establish the appropriate operating conditions of SEM and reproducibility as well as to examine the applicability of the method. The grayscale values converted from each pixel of SEI were used to determine the vitrification rate of pottery, which in our study were artificially fired specimens composed of three types of clay. A comparison between the vitrification rate value and appearance temperature of minerals shows that mullite formation starts at 1,100°C, during which the vitrification rate rapidly increases by over 10%. In consequence, the result presented here demonstrates that the new method can be applied to estimate the firing temperature of pottery.

  15. Study on Image Drift Induced by Charging during Observation by Scanning Electron Microscope

    NASA Astrophysics Data System (ADS)

    Okai, Nobuhiro; Sohda, Yasunari

    2012-06-01

    The mechanism of image drift in the observation of a boundary between a metal and an insulator by scanning electron microscope (SEM) is clarified by electron-trajectory simulation and experiment. In the region involving a straight boundary between a large-area metal layer and an insulating substrate, the largest image drift is expected to be observed owing to an asymmetric charging on the sample surface. The simulation result shows that a metal-insulator boundary in the SEM image shifts toward the metal part over several seconds, which is induced by a positively charged area outside of the irradiation region in the insulator part. This simulation result is confirmed to qualitatively coincide with the experimental one. In addition, we demonstrate that the direction and magnitude of the image drift can be controlled by changing the charging voltage of the insulating substrate by applying a bias voltage to the anode facing the sample surface.

  16. A scanning electron microscope examination of silver cones removed from endodontically treated teeth. 1972.

    PubMed

    Seltzer, Samuel; Green, Daniel B; Weiner, Neil; DeRenzis, Frank

    2004-07-01

    Twenty-five silver cones were removed from teeth which had been treated endodontically from 3 months to 20 years previously. Examination by the scanning electron microscope revealed that these cones were moderately to severely corroded. The corrosion patterns were described as ranging from pitting to deep crater formation with globular or spherical agglomerations. Examinations with the electron probe showed sulfur peaks on the corroded portions of the cones. X-ray diffraction analyses indicated that the chemical compounds formed were silver sulfides, silver sulfates, silver carbonates, and silver amine sulfate amide hydrates. Tissue culture studies indicated that the corrosion products were highly cytotoxic. The mechanisms for the formation of the corrosion products have been postulated as being due to plastic deformations and metal transfer to the silver cones, plus contact of the silver with tissue fluids.

  17. Sensitivity Analysis of X-ray Spectra from Scanning Electron Microscopes

    SciTech Connect

    Miller, Thomas Martin; Patton, Bruce W.; Weber, Charles F.; Bekar, Kursat B.

    2014-10-01

    The primary goal of this project is to evaluate x-ray spectra generated within a scanning electron microscope (SEM) to determine elemental composition of small samples. This will be accomplished by performing Monte Carlo simulations of the electron and photon interactions in the sample and in the x-ray detector. The elemental inventories will be determined by an inverse process that progressively reduces the difference between the measured and simulated x-ray spectra by iteratively adjusting composition and geometric variables in the computational model. The intended benefit of this work will be to develop a method to perform quantitative analysis on substandard samples (heterogeneous phases, rough surfaces, small sizes, etc.) without involving standard elemental samples or empirical matrix corrections (i.e., true standardless quantitative analysis).

  18. Compact device for cleaning scanner-mounted scanning tunneling microscope tips using electron bombardment

    NASA Astrophysics Data System (ADS)

    Hellmann, D.; Worbes, L.; Kittel, A.

    2011-08-01

    Most scanning probe techniques rely on the assumption that both sample and tip are free from adsorbates, residues, and oxide not deposited intentionally. Getting a clean sample surface can be readily accomplished by applying ion sputtering and subsequent annealing, whereas finding an adequate treatment for tips is much more complicated. The method of choice would effectively desorb undesired compounds without reducing the sharpness or the general geometry of the tip. Several devices which employ accelerated electrons to achieve this are described in the literature. To minimize both the effort to implement this technique in a UHV chamber and the overall duration of the cleaning procedure, we constructed a compact electron source fitted into a sample holder, which can be operated in a standard Omicron variable-temperature (VT)-STM while the tip stays in place. This way a maximum of compatibility with existing systems is achieved and short turnaround times are possible for tip cleaning.

  19. Local crystal structure analysis with 10-pm accuracy using scanning transmission electron microscopy.

    PubMed

    Saito, Mitsuhiro; Kimoto, Koji; Nagai, Takuro; Fukushima, Shun; Akahoshi, Daisuke; Kuwahara, Hideki; Matsui, Yoshio; Ishizuka, Kazuo

    2009-06-01

    We demonstrate local crystal structure analysis based on annular dark-field (ADF) imaging in scanning transmission electron microscopy (STEM). Using a stabilized STEM instrument and customized software, we first realize high accuracy of elemental discrimination and atom-position determination with a 10-pm-order accuracy, which can reveal major cation displacements associated with a variety of material properties, e.g. ferroelectricity and colossal magnetoresistivity. A-site ordered/disordered perovskite manganites Tb(0.5)Ba(0.5)MnO(3) are analysed; A-site ordering and a Mn-site displacement of 12 pm are detected in each specific atomic column. This method can be applied to practical and advanced materials, e.g. strongly correlated electron materials.

  20. Scanning-electron-microscopy observations and mechanical characteristics of ion-beam-sputtered surgical implant alloys

    NASA Technical Reports Server (NTRS)

    Weigand, A. J.; Meyer, M. L.; Ling, J. S.

    1977-01-01

    An electron bombardment ion thruster was used as an ion source to sputter the surfaces of orthopedic prosthetic metals. Scanning electron microscopy photomicrographs were made of each ion beam textured surface. The effect of ion texturing an implant surface on its bond to bone cement was investigated. A Co-Cr-W alloy and surgical stainless steel were used as representative hard tissue implant materials to determine effects of ion texturing on bulk mechanical properties. Work was done to determine the effect of substrate temperature on the development of an ion textured surface microstructure. Results indicate that the ultimate strength of the bulk materials is unchanged by ion texturing and that the microstructure will develop more rapidly if the substrate is heated prior to ion texturing.

  1. Direct mapping of Li distribution in electrochemically lithiated graphite anodes using scanning Auger electron microscopy

    NASA Astrophysics Data System (ADS)

    Ishida, Nobuyuki; Fukumitsu, Hitoshi; Kimura, Hiroshi; Fujita, Daisuke

    2014-02-01

    The spatial distribution of Li ions in electrochemically lithiated graphite anodes for Li-ion battery is characterized by scanning Auger electron microscopy. We show that direct mapping of Li KVV peak intensity reveal the spatial distribution of intercalated Li and its chemical state in a quantitative manner. Furthermore, we demonstrate that mapping using a C KVV peak also reflects the spatial distribution of Li due to the change in the electronic properties of C atoms induced by the electrode reaction (Li intercalation). Mapping measurements on three samples with different charging states (20%, 50%, and 100%) show that at the early stage of charging Li ions do not intercalate homogenously into all the graphite particles but selectively into some specific ones with higher rates. Our method provides the criteria to evaluate structure-correlated Li intercalation from nanometer- to micrometer-scale, such as conductivity network in the electrodes due to a non-uniform morphology of binder and conductive additives.

  2. Noise characteristics of the gas ionization cascade used in low vacuum scanning electron microscopy

    SciTech Connect

    Tileli, Vasiliki; Thiel, Bradley L.; Knowles, W. Ralph; Toth, Milos

    2009-07-01

    The noise characteristics of gas cascade amplified electron signals in low vacuum scanning electron microscopy (LVSEM) are described and analyzed. We derive expressions for each component contributing to the total noise culminating in a predictive, quantitative model that can be used for optimization of LVSEM operating parameters. Signal and noise behavior is characterized experimentally and used to validate the model. Under most operating conditions, the noise is dominated by the excess noise generated in the gas amplification cascade. At high gains, the excess noise increases proportionally with gain such that the signal-to-noise ratio is constant. The effects of several instrument operating parameters, including working distance, gas pressure, beam current, and detector bias, are condensed and presented in the form of a master curve.

  3. Dosimetric study of total skin irradiation with a scanning beam electron accelerator

    SciTech Connect

    Sharma, S.C.; Wilson, D.L.

    1987-05-01

    The Therac 20 6-MeV scanned electron beam may be used for partial or total skin therapy. The maximum field size at 1 m is 30 x 30 cm defined by a set of primary photon collimators in conjunction with secondary trimmers. We have studied electron beam profiles with and without trimmers at the nominal source--skin distance of 1 m versus extended distances of 3--5 m. We find that the trimmers limit the field size and add little to the beam uniformity at extended distances. Beam energy, dose distributions, and output factors at extended distances were measured for single and multiple field arrangements with and without trimmers. Beam parameters were measured after introducing a degrader that lowered the energy to 3.7 MeV.

  4. Dosimetric study of total skin irradiation with a scanning beam electron accelerator.

    PubMed

    Sharma, S C; Wilson, D L

    1987-01-01

    The Therac 20 6-MeV scanned electron beam may be used for partial or total skin therapy. The maximum field size at 1 m is 30 X 30 cm defined by a set of primary photon collimators in conjunction with secondary trimmers. We have studied electron beam profiles with and without trimmers at the nominal source-skin distance of 1 m versus extended distances of 3-5 m. We find that the trimmers limit the field size and add little to the beam uniformity at extended distances. Beam energy, dose distributions, and output factors at extended distances were measured for single and multiple field arrangements with and without trimmers. Beam parameters were measured after introducing a degrader that lowered the energy to 3.7 MeV.

  5. Achondrogenesis type I in three sibling fetuses. Scanning and transmission electron microscopic studies.

    PubMed

    Ornoy, A; Sekeles, E; Smith, P; Simkin, A; Kohn, G

    1976-01-01

    Three spontaneously aborted fetuses with Type I achondrogenesis in a family with a first cousin marriage are described. Studies by light microscopy revealed abnormal cartilage, enchondral, and periosteal bone, and normal tooth development with abnormal alveolar bone. Electron microscopic studies of cultured skin fibroblasts manifested structurally normal cells. Scanning electron microscopy studies had shown deficient intercartilaginous septa in the metaphysis, with abnormally large calcifying globules. In the diaphysis, the orientation of bone trabeculae and collagen fibers within the trabeculae was disturbed. The numerous osteocytic lucunae were wide and irregular in arrangement and shape. Type 2 achondrogenesis, as studied in these fetuses, is probably a widespread mesenchymal defect, manifested by abnormal calcification and ossification of enchondral and periosteal bone.

  6. Scanning electron microscope cathodoluminescence imaging of subgrain boundaries, twins and planar deformation features in quartz

    NASA Astrophysics Data System (ADS)

    Hamers, M. F.; Pennock, G. M.; Drury, M. R.

    2016-11-01

    The study of deformation features has been of great importance to determine deformation mechanisms in quartz. Relevant microstructures in both growth and deformation processes include dislocations, subgrains, subgrain boundaries, Brazil and Dauphiné twins and planar deformation features (PDFs). Dislocations and twin boundaries are most commonly imaged using a transmission electron microscope (TEM), because these cannot directly be observed using light microscopy, in contrast to PDFs. Here, we show that red-filtered cathodoluminescence imaging in a scanning electron microscope (SEM) is a useful method to visualise subgrain boundaries, Brazil and Dauphiné twin boundaries. Because standard petrographic thin sections can be studied in the SEM, the observed structures can be directly and easily correlated to light microscopy studies. In contrast to TEM preparation methods, SEM techniques are non-destructive to the area of interest on a petrographic thin section.

  7. Biological application of Compressed Sensing Tomography in the Scanning Electron Microscope

    NASA Astrophysics Data System (ADS)

    Ferroni, Matteo; Signoroni, Alberto; Sanzogni, Andrea; Masini, Luca; Migliori, Andrea; Ortolani, Luca; Pezza, Alessandro; Morandi, Vittorio

    2016-09-01

    The three-dimensional tomographic reconstruction of a biological sample, namely collagen fibrils in human dermal tissue, was obtained from a set of projection-images acquired in the Scanning Electron Microscope. A tailored strategy for the transmission imaging mode was implemented in the microscope and proved effective in acquiring the projections needed for the tomographic reconstruction. Suitable projection alignment and Compressed Sensing formulation were used to overcome the limitations arising from the experimental acquisition strategy and to improve the reconstruction of the sample. The undetermined problem of structure reconstruction from a set of projections, limited in number and angular range, was indeed supported by exploiting the sparsity of the object projected in the electron microscopy images. In particular, the proposed system was able to preserve the reconstruction accuracy even in presence of a significant reduction of experimental projections.

  8. Segmentation of scanning electron microscopy images from natural rubber samples with gold nanoparticles using starlet wavelets.

    PubMed

    de Siqueira, Alexandre Fioravante; Cabrera, Flávio Camargo; Pagamisse, Aylton; Job, Aldo Eloizo

    2014-01-01

    Electronic microscopy has been used for morphology evaluation of different materials structures. However, microscopy results may be affected by several factors. Image processing methods can be used to correct and improve the quality of these results. In this article, we propose an algorithm based on starlets to perform the segmentation of scanning electron microscopy images. An application is presented in order to locate gold nanoparticles in natural rubber membranes. In this application, our method showed accuracy greater than 85% for all test images. Results given by this method will be used in future studies, to computationally estimate the density distribution of gold nanoparticles in natural rubber samples and to predict reduction kinetics of gold nanoparticles at different time periods.

  9. Biological application of Compressed Sensing Tomography in the Scanning Electron Microscope

    PubMed Central

    Ferroni, Matteo; Signoroni, Alberto; Sanzogni, Andrea; Masini, Luca; Migliori, Andrea; Ortolani, Luca; Pezza, Alessandro; Morandi, Vittorio

    2016-01-01

    The three-dimensional tomographic reconstruction of a biological sample, namely collagen fibrils in human dermal tissue, was obtained from a set of projection-images acquired in the Scanning Electron Microscope. A tailored strategy for the transmission imaging mode was implemented in the microscope and proved effective in acquiring the projections needed for the tomographic reconstruction. Suitable projection alignment and Compressed Sensing formulation were used to overcome the limitations arising from the experimental acquisition strategy and to improve the reconstruction of the sample. The undetermined problem of structure reconstruction from a set of projections, limited in number and angular range, was indeed supported by exploiting the sparsity of the object projected in the electron microscopy images. In particular, the proposed system was able to preserve the reconstruction accuracy even in presence of a significant reduction of experimental projections. PMID:27646194

  10. Unscrambling Mixed Elements using High Angle Annular Dark Field Scanning Transmission Electron Microscopy

    NASA Astrophysics Data System (ADS)

    van den Bos, Karel H. W.; De Backer, Annick; Martinez, Gerardo T.; Winckelmans, Naomi; Bals, Sara; Nellist, Peter D.; Van Aert, Sandra

    2016-06-01

    The development of new nanocrystals with outstanding physicochemical properties requires a full three-dimensional (3D) characterization at the atomic scale. For homogeneous nanocrystals, counting the number of atoms in each atomic column from high angle annular dark field scanning transmission electron microscopy images has been shown to be a successful technique to get access to this 3D information. However, technologically important nanostructures often consist of more than one chemical element. In order to extend atom counting to heterogeneous materials, a new atomic lensing model is presented. This model takes dynamical electron diffraction into account and opens up new possibilities for unraveling the 3D composition at the atomic scale. Here, the method is applied to determine the 3D structure of Au@Ag core-shell nanorods, but it is applicable to a wide range of heterogeneous complex nanostructures.

  11. High contrast en bloc staining of neuronal tissue for field emission scanning electron microscopy

    PubMed Central

    Tapia, Juan C.; Kasthuri, Narayanan; Hayworth, Kenneth; Schalek, Richard; Lichtman, Jeff W.; Smith, Stephen J; Buchanan, JoAnn

    2013-01-01

    Conventional heavy metal post staining methods on thin sections lend contrast but often cause contamination. To avoid this problem, we tested several en bloc staining techniques to contrast tissue in serial sections mounted on solid substrates for examination by Field Emission Scanning Electron Microscope (FESEM). Because FESEM section imaging requires that specimens have higher contrast and greater electrical conductivity than transmission electron microscope (TEM) samples, our technique utilizes osmium impregnation (OTO) to make the samples conductive while heavily staining membranes for segmentation studies. Combining this step with other classic heavy metal en bloc stains including uranyl acetate, lead aspartate, copper sulfate and lead citrate produced clean, highly contrasted TEM and SEM samples of insect, fish, and mammalian nervous system. This protocol takes 7–15 days to prepare resin embedded tissue, cut sections and produce serial section images. PMID:22240582

  12. Identification of light elements in silicon nitride by aberration-corrected scanning transmission electron microscopy.

    PubMed

    Idrobo, Juan C; Walkosz, Weronika; Klie, Robert F; Oğüt, Serdar

    2012-12-01

    In silicon nitride structural ceramics, the overall mechanical and thermal properties are controlled by the atomic and electronic structures at the interface between the ceramic grains and the amorphous intergranular films (IGFs) formed by various sintering additives. In the last ten years the atomic arrangements of heavy elements (rare-earths) at the Si(3)N(4)/IGF interfaces have been resolved. However, the atomic position of light elements, without which it is not possible to obtain a complete description of the interfaces, has been lacking. This review article details the authors' efforts to identify the atomic arrangement of light elements such as nitrogen and oxygen at the Si(3)N(4)/SiO(2) interface and in bulk Si(3)N(4) using aberration-corrected scanning transmission electron microscopy.

  13. Annular dark-field scanning transmission electron microscopy (ADF-STEM) tomography of polymer systems.

    PubMed

    Lu, Kangbo; Sourty, Erwan; Loos, Joachim

    2010-08-01

    We have utilized bright-field conventional transmission electron microscopy tomography and annular dark-field scanning transmission electron microscopy (ADF-STEM) tomography to characterize a well-defined carbon black (CB)-filled polymer nanocomposite with known CB volume concentration. For both imaging methods, contrast can be generated between the CB and the surrounding polymer matrix. The involved contrast mechanisms, in particular for ADF-STEM, will be discussed in detail. The obtained volume reconstructions were analysed and the CB volume concentrations were carefully determined from the reconstructed data. For both imaging modes, the measured CB volume concentrations are substantially different and only quantification based on the ADF-STEM data revealed about the same value as the known CB loading. Moreover, when applying low-convergence angles for imaging ADF-STEM tomography, data can be obtained of micrometre-thick samples.

  14. Unscrambling Mixed Elements using High Angle Annular Dark Field Scanning Transmission Electron Microscopy.

    PubMed

    van den Bos, Karel H W; De Backer, Annick; Martinez, Gerardo T; Winckelmans, Naomi; Bals, Sara; Nellist, Peter D; Van Aert, Sandra

    2016-06-17

    The development of new nanocrystals with outstanding physicochemical properties requires a full three-dimensional (3D) characterization at the atomic scale. For homogeneous nanocrystals, counting the number of atoms in each atomic column from high angle annular dark field scanning transmission electron microscopy images has been shown to be a successful technique to get access to this 3D information. However, technologically important nanostructures often consist of more than one chemical element. In order to extend atom counting to heterogeneous materials, a new atomic lensing model is presented. This model takes dynamical electron diffraction into account and opens up new possibilities for unraveling the 3D composition at the atomic scale. Here, the method is applied to determine the 3D structure of Au@Ag core-shell nanorods, but it is applicable to a wide range of heterogeneous complex nanostructures.

  15. Silver methenamine staining for scanning electron microscopy of bone sections containing biomaterials.

    PubMed

    Frayssinet, P; Hanker, J S; Rouquet, N; Primout, I; Giammara, B

    1999-01-01

    Sections of tissue containing orthopedic materials are currently used to study the compatibility of those materials and to perform electron probe microanalysis at the material-tissue interface. Identification of the cells in contact with the material by Scanning electron microscopy (SEM) is of interest. We have developed a method for staining cells and tissue structures embedded in polymethyl methacrylate with silver methenamine once the sections have been obtained. Sections were prepared by grinding, and the silver methenamine was applied after oxidation with periodic acid. The procedure was carried out in a microwave oven. Backscatter SEM showed staining of the cell nucleus membrane, chromatin, the nuclear organizers, and the chromosomes of dividing cells. The cytoplasm and the cytoplasmic membrane were also stained. Collagen fibers of the extracellular matrix and the mineralized matrix of bone were labeled. Material particles in the macrophages were easily recognizable and Energy-Dispersive Spectrometer were not impaired by the presence of silver in the preparation.

  16. Investigating the use of in situ liquid cell scanning transmission electron microscopy

    SciTech Connect

    Nguy, Amanda

    2016-02-19

    Engineering nanoparticles with desired shape-dependent properties is the key to many applications in nanotechnology. Although many synthetic procedures exist to produce anisotropic gold nanoparticles, the dynamics of growth are typically unknown or hypothetical. In the case of seed-mediated growth in the presence of DNA into anisotropic nanoparticles, it is not known exactly how DNA directs growth into specific morphologies. A series of preliminary experiments were carried out to contribute to the investigation of the possible mechanism of DNA-mediated growth of gold nanoprisms into gold nanostars using liquid cell scanning transmission electron microscopy (STEM). Imaging in the liquid phase was achieved through the use of a liquid cell platform and liquid cell holder that allow the sample to be contained within a “chip sandwich” between two electron transparent windows. Ex situ growth experiments were performed using Au-T30 NPrisms (30-base thymine oligonucleotide-coated gold nanoprisms) that are expected to grow into gold nanostars. Growth to form these nanostars were imaged using TEM (transmission electron microscopy) and liquid cell STEM (scanning transmission electron microscopy). An attempt to perform in situ growth experiments with the same Au-T30 nanoprisms revealed challenges in obtaining desired morphology results due to the environmental differences within the liquid cell compared to the ex situ environment. Different parameters in the experimental method were explored including fluid line set up, simultaneous and alternating reagent addition, and the effect of different liquid cell volumes to ensure adequate flow of reagents into the liquid cell. Lastly, the binding affinities were compared for T30 and A30 DNA incubated with gold nanoparticles using zeta potential measurements, absorption spectroscopy, and isothermal titration calorimetry (ITC). It was previously reported thymine bases have a lower binding affinity to gold surfaces than adenine

  17. Visualising impregnated chitosan in Pinus radiata early wood cells using light and scanning electron microscopy.

    PubMed

    Singh, Adya P; Singh, Tripti; Rickard, Catherine L

    2010-04-01

    Chitosan, a deacetylated product of an abundant naturally occurring biopolymer chitin, has been used in a range of applications, particularly in food and health areas, as an antimicrobial agent. In the work reported here Pinus radiata wood was impregnated with chitosan as an environmentally compatible organic biocide (Eikenes et al., 2005a,b) to protect wood against wood deteriorating microorganisms and to thus prolong the service life of wooden products. We developed sample preparation techniques targeted to visualise impregnated chitosan within wood tissues using light microscope and field-emission scanning electron microscope (FE-SEM). Sections were viewed with the light microscope without staining with a dye as well as after staining with the dye toluidine blue. Light microscopy was also undertaken on sections that had been stained with 1% aqueous osmium tetroxide (OsO(4)). For SEM observations, the sections were treated with OsO(4) and then examined with the FE-SEM, first in the secondary electron imaging mode (SEI) and then in the backscattered electron imaging (BEI) mode, imaging the same areas of a section in both SEI and BEI modes. The preparation techniques employed and the combined use of light and scanning electron microscopy provided valuable complementary information, revealing that chitosan had penetrated into the cavities (cell lumens, intercellular spaces) of all sizes present within wood tissues and had also impregnated early wood cell walls. The information obtained is discussed in relation to its importance in further development of chitosan formulations and refinement of impregnation technologies to optimise chitosan impregnation into and distribution within wood tissues as well as in assessing chitosan efficacy.

  18. Scanning L Band Active Passive Validation Experiment 2013

    NASA Astrophysics Data System (ADS)

    Joseph, A. T.; Kim, E. J.; Faulkner, T.; Patel, H.; Cosh, M. H.

    2014-12-01

    SLAP (Scanning L-band Active Passive) comprises of a fully polarimetric L-band radiometer and fully polarimetric L-band radar with a shared antenna. SLAP is designed to be compatible with several aircrafts; specifically, C-23, Twin Otter, P-3, and C-130. SLAP is designed for simplicity, accuracy, & reliability. It leverages, as much as possible, existing instruments, hardware, and software in order to minimize cost, time, and risk.The SLAP airborne/ground campaign is designed to conduct flight testing and ground truth for the airborne instrument. The campaign took place the third week of December 2013 in Eastern Shore, MD. SLAP contributes to the NASA's core mission because of its ability to serve as an airborne simulator for the SMAP (Soil Moisture Active Passive) satellite mission, one of NASA's flagship missions scheduled to launch in January 2015. A 3-day aircraft validation campaign was conducted where the new SLAP instrument flew three separate days over the proposed sampling region. The study area is a mixed agriculture and forest site located about 1 hour east of Washington, DC on the Eastern Shore (of the Chesapeake Bay). This region is located on the Delmarva Peninsula. The advantages of the selected site are: (1) Site was used before in previous field campaign (SMAPVEX08) (2) ARS HRSL has some established sampling sites within region (3) Dynamic variation in land cover (4) Variety of plant structures and densities. The goal of this campaign was to fly the instrument over the proposed site before a rain event, then have 2 other flights after the rain event to capture a dry down. In conjunction with the aircraft, there was in-situ ground sampling. Ground observations were collected concurrent with aircraft flights. These included soil moisture, soil temperature, surface temperature, surface roughness and vegetation parameters. Forest sites were monitored with small temporary networks of in situ sensors installed prior to the first flight. Soil moisture was

  19. 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.

  20. Novel scanning electron microscope bulge test technique integrated with loading function

    SciTech Connect

    Li, Chuanwei; Xie, Huimin E-mail: xiehm@mail.tsinghua.edu.cn; Liu, Zhanwei E-mail: xiehm@mail.tsinghua.edu.cn

    2014-10-15

    Membranes and film-on-substrate structures are critical elements for some devices in electronics industry and for Micro Electro Mechanical Systems devices. These structures are normally at the scale of micrometer or even nanometer. Thus, the measurement for the mechanical property of these membranes poses a challenge over the conventional measurements at macro-scales. In this study, a novel bulge test method is presented for the evaluation of mechanical property of micro thin membranes. Three aspects are discussed in the study: (a) A novel bulge test with a Scanning Electron Microscope system realizing the function of loading and measuring simultaneously; (b) a simplified Digital Image Correlation method for a height measurement; and (c) an imaging distortion correction by the introduction of a scanning Moiré method. Combined with the above techniques, biaxial modulus as well as Young's modulus of the polyimide film can be determined. Besides, a standard tensile test is conducted as an auxiliary experiment to validate the feasibility of the proposed method.

  1. Plasmonic Field Enhancement of Individual Nanoparticles by Correlated Scanning and Photoemission Electron Microscopy

    SciTech Connect

    Peppernick, Samuel J.; Joly, Alan G.; Beck, Kenneth M.; Hess, Wayne P.

    2011-01-21

    We present results of a combined two-photon photoemission and scanning electron microscopy investigation to determine the electromagnetic enhancement factors of silver-coated spherical nanoparticles deposited on an atomically flat mica substrate. Femtosecond laser excitation, of the nanoparticles, produces intense photoemission, attributed to near-resonant excitation of localized surface plasmons. Enhancement factors are determined by comparing the respective two-photon photoemission yield measured for equal areas between single nanoparticles to that of the surrounding flat surface. For s-polarized, 400 nm (~ 3.1 eV) femtosecond radiation a distribution of enhancement factors are found with a large percentage (77%) of the nanoparticles falling within a median range. A correlated scanning electron microscopy analysis demonstrated that the nanoparticles typifying the median of the distribution were characterized by ideal spherical shapes and defect-free morphologies. The single largest enhancement factors were in contrast produced by a very small percentage (8%) of the total, for which evidence of silver defect anomalies were found that contributed to the overall structure of the nanoparticle. Comparisons are made between the experimentally measured enhancement factors and previously reported theoretical predictions of the localized surface plasmon near-field intensities for isolated nanometer-sized silver spheres.

  2. Experimental white piedra: a robust approach to ultrastructural analysis, scanning electron microscopy and etiological discoveries.

    PubMed

    Inácio, Cicero P; Rocha, Ana Paula S; Barbosa, Renan do N; Oliveira, Neiva T; Silva, Josineide C; de Lima-Neto, Reginaldo G; Macêdo, Danielle Patrícia C; Neves, Rejane P

    2016-01-01

    White piedra is a fungal infection characterized by nodules comprised of Trichosporon species and restricted to the extrafollicular portion of the hair shaft. The diagnosis is based on clinical and mycological characteristics, and must be confirmed with a precise identification of the etiological agent. This research aimed to develop an in vitro infection model of white piedra and analyze its morphological and ultra-structural aspects. In the process, hair infection was induced using eight isolates of the genus Trichosporon maintained in the Culture Collection Micoteca URM. The ITS and IGS1 regions were sequenced for taxonomic confirmation. Scanning Electron Microscope (SEM) was performed at the Strategic Center for Northeast Technologies (CETENE). The scanning electron microscope was equipped with an Energy Dispersion Spectrometer (EDS). The Trichosporon isolates were identified as Trichosporon asahii (6) and Trichosporon montevideense (2) by internal transcript spacer (ITS) region and intergenic spacer 1 region (IGS1) sequencing. All eight strains were used to induce the in vitro hair infection, and nodules formed after the incubation period. Temperature variations and high humidity were not observed to be related to the development of this hair disease. The main chemical constituents detected in the nodules were carbon, nitrogen and oxygen, as well as a low level of sulfur. The absence of calcium, combined with the low level of sulfur, might explain the soft nature of the white piedra nodules. This study demonstrated that several Trichosporon species may be responsible for causing white piedra.

  3. Histological and scanning electron microscopy assessment of various vital pulp-therapy materials.

    PubMed

    Dominguez, Mercedes S; Witherspoon, David E; Gutmann, James L; Opperman, Lynne A

    2003-05-01

    Pulp capping and pulpotomy procedures were performed on 15 male mongrel dogs. Three materials were used: calcium hydroxide, acid-etched dentin bonding, and mineral trioxide aggregate. Six of the animals were killed at 50 days and nine were killed at 150 days. Samples from 11 dogs were used for histological evaluation, and the remaining dog samples were used for scanning electron microscopy evaluation. Each slide was graded histologically according to previously published criteria. Scanning electron microscopy analysis was performed, and the weight percentage of elements found in the dentin of a nontreated tooth versus the bridge formed in the exposed specimen was established. By evaluating pulp inflammation in vital pulp-therapy treatments, it was found that mineral trioxide aggregate was not significantly different from the untreated control group, both in pulp-capping procedures at 50 days (p = 0.357) or 150 days (p = 0.198) and pulpotomy procedures at 50 days (p = 0.357) or 150 days (p = 0.198). Moreover, histologically mineral trioxide aggregate was a considerably better material than calcium hydroxide or acid-etched dentin bonding in maintaining the integrity of the pulp.

  4. Microfluidic device for a rapid immobilization of zebrafish larvae in environmental scanning electron microscopy.

    PubMed

    Akagi, Jin; Zhu, Feng; Skommer, Joanna; Hall, Chris J; Crosier, Philip S; Cialkowski, Michal; Wlodkowic, Donald

    2015-03-01

    Small vertebrate model organisms have recently gained popularity as attractive experimental models that enhance our understanding of human tissue and organ development. Despite a large body of evidence using optical spectroscopy for the characterization of small model organism on chip-based devices, no attempts have been so far made to interface microfabricated technologies with environmental scanning electron microscopy (ESEM). Conventional scanning electron microscopy requires high vacuum environments and biological samples must be, therefore, submitted to many preparative procedures to dehydrate, fix, and subsequently stain the sample with gold-palladium deposition. This process is inherently low-throughput and can introduce many analytical artifacts. This work describes a proof-of-concept microfluidic chip-based system for immobilizing zebrafish larvae for ESEM imaging that is performed in a gaseous atmosphere, under low vacuum mode and without any need for sample staining protocols. The microfabricated technology provides a user-friendly and simple interface to perform ESEM imaging on zebrafish larvae. Presented lab-on-a-chip device was fabricated using a high-speed infrared laser micromachining in a biocompatible poly(methyl methacrylate) thermoplastic. It consisted of a reservoir with multiple semispherical microwells designed to hold the yolk of dechorionated zebrafish larvae. Immobilization of the larvae was achieved by a gentle suction generated during blotting of the medium. Trapping region allowed for multiple specimens to be conveniently positioned on the chip-based device within few minutes for ESEM imaging.

  5. New Aspidoderidae species parasite of Didelphis aurita (Mammalia: Didelphidae): a light and scanning electron microscopy approach.

    PubMed

    Chagas-Moutinho, V A; Sant'anna, V; Oliveira-Menezes, A; De Souza, W

    2014-02-01

    Nematodes of the family Aspidoderidae (Nematoda: Heterakoidea) Skrjabin and Schikobalova, 1947, are widely distributed in the Americas. The family Aspidoderidae includes the subfamilies Aspidoderinae Skrjabin and Schikobalova, 1947, and Lauroiinae Skrjabin and Schikobalova, 1951. These two subfamilies are delineated by the presence or absence of cephalic cordons at the anterior region. The nematodes in the subfamily Aspidoderinae, which includes the genus AspidoderaRailliet and Henry, 1912, are represented by nematodes with anterior cephalic cordons at the anterior end. The nematodes of the genus AspidoderaRailliet and Henry, 1912, are found in the cecum and large intestine of mammals of the orders Edentata, Marsupialia and Rodentia. Species within this genus have many morphological similarities. The use of scanning electron microscopy allows the specific characterization of the species within this genus. In the present work, we describe a new species of Aspidodera parasite of the large intestine of Didelphis aurita (Mammalia: Didelphidae) Wied-Neuwied, 1826, collected from Cachoeiras de Macacu, Rio de Janeiro. The combination of light and scanning electron microscopy allowed us a detailed analysis of this nematode.

  6. Evaluation of enteric matrix microspheres prepared by emulsion-solvent evaporation using scanning electron microscopy.

    PubMed

    Obeidat, W M; Price, J C

    2004-02-01

    Theophylline microspheres were prepared by the emulsion-solvent evaporation method using cellulose acetate butyrate (CAB381-20) and mixtures of CAB381-20(R) and cellulose acetate phthalate. The physical state of the drug, polymers and microspheres surfaces were determined using scanning electron microscopy. For those microspheres prepared using mixtures of CAB381-20 and cellulose acetate phthalate, scanning electron micrographs were taken before dissolution and also at different stages of dissolution (in SGF, pH 1.2 and in simulated intestinal fluid, pH 7.5). Micrographs were taken of the outside surfaces of the microspheres and of the cleaved microspheres showing their interiors (core). Drug crystals were observed on or near the surface of microspheres prepared from the polymer mixtures, while no drug particles or crystals were seen on the surfaces of microspheres prepared solely from CAB381-20. An acid wash for less than 2 min was capable of extracting all drug on the surface of the microspheres prepared from a mixture of CAB381-20 and cellulose acetate phthalate. The absence of drug crystals on the surface of CAB381-20 microspheres is believed to prevent initial drug release and create a lag time in release profiles. Results suggest that in both microsphere formulations, a layer of drug-free polymer is formed outside the core matrix and is believed to be responsible for the near zero-order release profiles.

  7. Calibration improvements to electronically scanned pressure systems and preliminary statistical assessment

    NASA Technical Reports Server (NTRS)

    Everhart, Joel L.

    1996-01-01

    Orifice-to-orifice inconsistencies in data acquired with an electronically-scanned pressure system at the beginning of a wind tunnel experiment forced modifications to the standard, instrument calibration procedures. These modifications included a large increase in the number of calibration points which would allow a critical examination of the calibration curve-fit process, and a subsequent post-test reduction of the pressure data. Evaluation of these data has resulted in an improved functional representation of the pressure-voltage signature for electronically-scanned pressures sensors, which can reduce the errors due to calibration curve fit to under 0.10 percent of reading compared to the manufacturer specified 0.10 percent of full scale. Application of the improved calibration function allows a more rational selection of the calibration set-point pressures. These pressures should be adjusted to achieve a voltage output which matches the physical shape of the pressure-voltage signature of the sensor. This process is conducted in lieu of the more traditional approach where a calibration pressure is specified and the resulting sensor voltage is recorded. The fifteen calibrations acquired over the two-week duration of the wind tunnel test were further used to perform a preliminary, statistical assessment of the variation in the calibration process. The results allowed the estimation of the bias uncertainty for a single instrument calibration; and, they form the precursor for more extensive and more controlled studies in the laboratory.

  8. Anatomical descriptions of silicified woods from Madagascar and Indonesia by scanning electron microscopy.

    PubMed

    Yoon, Chul Jong; Kim, Ki Woo

    2008-10-01

    Fine structure and tissue substitution by minerals were investigated in silicified woods from Madagascar and Indonesia by scanning electron microscopy and X-ray microanalysis. The silicified woods maintained the exterior morphology of once grown trees and showed typical inner structures of conifers. Radial planes of the silicified wood from Madagascar revealed tracheids as a major component of the axial system in the secondary xylem. Tracheids were mainly characterized by numerous bordered pits where a thickening in the middle (torus) was surrounded with the membrane (margo). The torus appeared to contrast with the fibrillar network of the margo. As a component of the axial system in the secondary phloem, sieve elements were found to have many sieve pores that were filled with seemingly crystalline materials. To correlate the colors of the silicified wood from Indonesia with elemental composition, energy-dispersive X-ray spectrometry was employed in this study. Silicon was present as a basic component of the silicified wood. Calcium and iron were detected from red-colored regions, whereas magnesium was found in blue-colored regions. These results suggest that tissues of silicified woods had been substituted by minerals over the past period, while retaining the inherent morphology of the tree species. Scanning electron microscopy and X-ray microanalysis could be applied to unravel structural details and composition of plant fossils in palaeobotany.

  9. Immuno-electron microscopy of primary cell cultures from genetically modified animals in liquid by atmospheric scanning electron microscopy.

    PubMed

    Kinoshita, Takaaki; Mori, Yosio; Hirano, Kazumi; Sugimoto, Shinya; Okuda, Ken-ichi; Matsumoto, Shunsuke; Namiki, Takeshi; Ebihara, Tatsuhiko; Kawata, Masaaki; Nishiyama, Hidetoshi; Sato, Mari; Suga, Mitsuo; Higashiyama, Kenichi; Sonomoto, Kenji; Mizunoe, Yoshimitsu; Nishihara, Shoko; Sato, Chikara

    2014-04-01

    High-throughput immuno-electron microscopy is required to capture the protein-protein interactions realizing physiological functions. Atmospheric scanning electron microscopy (ASEM) allows in situ correlative light and electron microscopy of samples in liquid in an open atmospheric environment. Cells are cultured in a few milliliters of medium directly in the ASEM dish, which can be coated and transferred to an incubator as required. Here, cells were imaged by optical or fluorescence microscopy, and at high resolution by gold-labeled immuno-ASEM, sometimes with additional metal staining. Axonal partitioning of neurons was correlated with specific cytoskeletal structures, including microtubules, using primary-culture neurons from wild type Drosophila, and the involvement of ankyrin in the formation of the intra-axonal segmentation boundary was studied using neurons from an ankyrin-deficient mutant. Rubella virus replication producing anti-double-stranded RNA was captured at the host cell's plasma membrane. Fas receptosome formation was associated with clathrin internalization near the surface of primitive endoderm cells. Positively charged Nanogold clearly revealed the cell outlines of primitive endoderm cells, and the cell division of lactic acid bacteria. Based on these experiments, ASEM promises to allow the study of protein interactions in various complexes in a natural environment of aqueous liquid in the near future.

  10. Study of fossil bones by synchrotron radiation micro-spectroscopic techniques and scanning electron microscopy.

    PubMed

    Zougrou, I M; Katsikini, M; Pinakidou, F; Paloura, E C; Papadopoulou, L; Tsoukala, E

    2014-01-01

    Earlymost Villafranchian fossil bones of an artiodactyl and a perissodactyl from the Milia excavation site in Grevena, Greece, were studied in order to evaluate diagenetic effects. Optical microscopy revealed the different bone types (fibro-lamellar and Haversian, respectively) of the two fragments and their good preservation state. The spatial distribution of bone apatite and soil-originating elements was studied using micro-X-ray fluorescence (µ-XRF) mapping and scanning electron microscopy. The approximate value of the Ca/P ratio was 2.2, as determined from scanning electron microscopy measurements. Bacterial boring was detected close to the periosteal region and Fe bearing oxides were found to fill bone cavities, e.g. Haversian canals and osteocyte lacunae. In the perissodactyl bone considerable amounts of Mn were detected close to cracks (the Mn/Fe weight ratio takes values up to 3.5). Goethite and pyrite were detected in both samples by means of metallographic microscopy. The local Ca/P ratio determined with µ-XRF varied significantly in metal-poor spots indicating spatial inhomogeneities in the ionic substitutions. XRF line scans that span the bone cross sections revealed that Fe and Mn contaminate the bones from both the periosteum and medullar cavity and aggregate around local maxima. The formation of goethite, irrespective of the local Fe concentration, was verified by the Fe K-edge X-ray absorption fine structure (XAFS) spectra. Finally, Sr K-edge extended XAFS (EXAFS) revealed that Sr substitutes for Ca in bone apatite without obvious preference to the Ca1 or Ca2 unit-cell site occupation.

  11. Quantitative atomic resolution mapping using high-angle annular dark field scanning transmission electron microscopy.

    PubMed

    Van Aert, S; Verbeeck, J; Erni, R; Bals, S; Luysberg, M; Van Dyck, D; Van Tendeloo, G

    2009-09-01

    A model-based method is proposed to relatively quantify the chemical composition of atomic columns using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) images. The method is based on a quantification of the total intensity of the scattered electrons for the individual atomic columns using statistical parameter estimation theory. In order to apply this theory, a model is required describing the image contrast of the HAADF STEM images. Therefore, a simple, effective incoherent model has been assumed which takes the probe intensity profile into account. The scattered intensities can then be estimated by fitting this model to an experimental HAADF STEM image. These estimates are used as a performance measure to distinguish between different atomic column types and to identify the nature of unknown columns with good accuracy and precision using statistical hypothesis testing. The reliability of the method is supported by means of simulated HAADF STEM images as well as a combination of experimental images and electron energy-loss spectra. It is experimentally shown that statistically meaningful information on the composition of individual columns can be obtained even if the difference in averaged atomic number Z is only 3. Using this method, quantitative mapping at atomic resolution using HAADF STEM images only has become possible without the need of simultaneously recorded electron energy loss spectra.

  12. Serial Block-Face Scanning Electron Microscopy to Reconstruct Three-Dimensional Tissue Nanostructure

    PubMed Central

    Horstmann, Heinz

    2004-01-01

    Three-dimensional (3D) structural information on many length scales is of central importance in biological research. Excellent methods exist to obtain structures of molecules at atomic, organelles at electron microscopic, and tissue at light-microscopic resolution. A gap exists, however, when 3D tissue structure needs to be reconstructed over hundreds of micrometers with a resolution sufficient to follow the thinnest cellular processes and to identify small organelles such as synaptic vesicles. Such 3D data are, however, essential to understand cellular networks that, particularly in the nervous system, need to be completely reconstructed throughout a substantial spatial volume. Here we demonstrate that datasets meeting these requirements can be obtained by automated block-face imaging combined with serial sectioning inside the chamber of a scanning electron microscope. Backscattering contrast is used to visualize the heavy-metal staining of tissue prepared using techniques that are routine for transmission electron microscopy. Low-vacuum (20–60 Pa H2O) conditions prevent charging of the uncoated block face. The resolution is sufficient to trace even the thinnest axons and to identify synapses. Stacks of several hundred sections, 50–70 nm thick, have been obtained at a lateral position jitter of typically under 10 nm. This opens the possibility of automatically obtaining the electron-microscope-level 3D datasets needed to completely reconstruct the connectivity of neuronal circuits. PMID:15514700

  13. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    DOE PAGES

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; ...

    2016-02-29

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, makingmore » it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Ultimately, simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.« less

  14. Weak-beam scanning transmission electron microscopy for quantitative dislocation density measurement in steels.

    PubMed

    Yoshida, Kenta; Shimodaira, Masaki; Toyama, Takeshi; Shimizu, Yasuo; Inoue, Koji; Yoshiie, Toshimasa; Milan, Konstantinovic J; Gerard, Robert; Nagai, Yasuyoshi

    2017-01-17

    To evaluate dislocations induced by neutron irradiation, we developed a weak-beam scanning transmission electron microscopy (WB-STEM) system by installing a novel beam selector, an annular detector, a high-speed CCD camera and an imaging filter in the camera chamber of a spherical aberration-corrected transmission electron microscope. The capabilities of the WB-STEM with respect to wide-view imaging, real-time diffraction monitoring and multi-contrast imaging are demonstrated using typical reactor pressure vessel steel that had been used in an European nuclear reactor for 30 years as a surveillance test piece with a fluence of 1.09 × 10(20) neutrons cm(-)(2) The quantitatively measured size distribution (average loop size = 3.6 ± 2.1 nm), number density of the dislocation loops (3.6 × 10(22) m(-3)) and dislocation density (7.8 × 10(13) m m(-)(3)) were carefully compared with the values obtained via conventional weak-beam transmission electron microscopy studies. In addition, cluster analysis using atom probe tomography (APT) further demonstrated the potential of the WB-STEM for correlative electron tomography/APT experiments.

  15. The Integration of Scanning Electron Microscopy, Scanning Probe Microscopy, and Luminescence Spectroscopy in one Platform: New Opportunities and Applications in Photovoltaics

    NASA Astrophysics Data System (ADS)

    Romero, Manuel

    2012-02-01

    We have recently integrated scanning tunneling microscopy (STM), atomic force microscopy (AFM), and near-field scanning optical microscopy (NSOM) onto the mechanical stage of a scanning electron microscope compatible with operation under high vacuum and the use of cryogenics. This instrument is unique in the sense that is not just the assembly of different microscopes but an integrated platform in which both the electron beam and the ultrasharp tip of the AFM/STM/NSOM can be controlled simultaneously and independently as excitation or sensing elements, providing innovative modes of operation and access to optoelectronic properties in the micro and nanoscale not accessible before. Furthermore, this instrument is equipped with focused laser illumination of the tip and detection of luminescence and can be used to measure cathodoluminescence, scanning tunneling luminescence, photoluminescence, and electroluminescence, all with high resolution. In this contribution, we review the application of these techniques to the development of second- and third-generation photovoltaics (PV) beyond those commercially available today. Among these applications, we present the luminescence and electron transport across single grain boundaries in chalcopyrite and kesterite compounds, the detection of single molecule species using plasmonics, the nanoscale imaging of the exciton transport in organic semiconductors, and the insitu manipulation and measurement of nanowires.

  16. Observation Technique of Surface Magnetic Structure Using Type-I Magnetic Contrast in the Scanning Electron Microscope

    NASA Astrophysics Data System (ADS)

    Kotera, Masatoshi; Katoh, Misao; Suga, Hiroshi

    1995-12-01

    The type-I magnetic contrast in the scanning electron microscope is simulated. The magnetic flux that leaked from the surface magnetic domain is calculated based on the Maxwell equation. Trajectories of secondary electrons emitted from the surface are traced considering this magnetic field and the electric field generated by the secondary electron detector. On the basis of the characteristic variation of the spatial deviation of electrons arriving at the detector, the original domain structure at the specimen surface is estimated.

  17. Mechanisms of hydrovolcanic pyroclast formation: Grain-size, scanning electron microscopy, and experimental studies

    NASA Astrophysics Data System (ADS)

    Wohletz, Kenneth H.

    1983-09-01

    Pyroclasts produced by explosive magma/water interactions are of various sizes and shapes. Data from analysis of over 200 samples of hydrovolcanic ash are interpreted by comparison with experimentally produced ash. Grain size and scanning electron microscopy (SEM) reveal information on the formation of hydrovolcanic pyroclasts. Strombolian explosions result from limited water interaction with magma and the pyroclasts produced are dominantly centimeter-sized. With increasing water interaction, hydrovolcanism increases in explosivity to Surtseyan and Vulcanian activity. These eruptions produce millimeter- to micron-sized pyroclasts. The abundance of fine ash (<63 μm diameter) increases from 5 to over 30 percent as water interaction reaches an explosive maximum. This maximum occurs with interactions of virtually equal volumes of melt and water. Five dominant pyroclast shape-types, determined by SEM, result from hydrovolcanic fragmentation: (1) blocky and equant; (2) vesicular and irregular with smooth surfaces; (3) moss-like and convoluted; (4) spherical or drop-like; and (5) plate-like. Types 1 and 2 dominate pyroclasts greater than 100 μm in diameter. Types 3 and 4 are typical of fine ash. Type 5 pyroclasts characterize ash less than 100 μm in diameter resulting from hydrovolcanic fragmentation after strong vesiculation. Fragmentation mechanisms observed in experimental melt/water interactions result from vapor-film generation, expansion, and collapse. Fragments of congealed melt are products of several alternative mechanisms including stress-wave cavitation, detonation waves, and fluid instability mixing. All result in rapid heat transfer. These mechanisms can explain the five observed pyroclast shapes. Stress-wave fracturing (cavitation) of the melt results from high pressure and temperature gradients at the melt/water interface. Simultaneous brittle fracture and quenching produces Type 1 pyroclasts. Type 2 develops smooth fused surfaces due to turbulent mixing

  18. Secretory glands and microvascular systems imaged in aqueous solution by atmospheric scanning electron microscopy (ASEM).

    PubMed

    Yamazawa, Toshiko; Nakamura, Naotoshi; Sato, Mari; Sato, Chikara

    2016-12-01

    Exocrine glands, e.g., salivary and pancreatic glands, play an important role in digestive enzyme secretion, while endocrine glands, e.g., pancreatic islets, secrete hormones that regulate blood glucose levels. The dysfunction of these secretory organs immediately leads to various diseases, such as diabetes or Sjögren's syndrome, by poorly understood mechanisms. Gland-related diseases have been studied by optical microscopy (OM), and at higher resolution by transmission electron microscopy (TEM) of Epon embedded samples, which necessitates hydrophobic sample pretreatment. Here, we report the direct observation of tissue in aqueous solution by atmospheric scanning electron microscopy (ASEM). Salivary glands, lacrimal glands, and pancreas were fixed, sectioned into slabs, stained with phosphotungstic acid (PTA), and inspected in radical scavenger d-glucose solution from below by an inverted scanning electron microscopy (SEM), guided by optical microscopy from above to target the tissue substructures. A 2- to 3-µm specimen thickness was visualized by the SEM. In secretory cells, cytoplasmic vesicles and other organelles were clearly imaged at high resolution, and the former could be classified according to the degree of PTA staining. In islets of Langerhans, the microvascular system used as an outlet by the secretory cells was also clearly observed. Microvascular system is also critically involved in the onset of diabetic complications and was clearly visible in subcutaneous tissue imaged by ASEM. The results suggest the use of in-solution ASEM for histology and to study vesicle secretion systems. Further, the high-throughput of ASEM makes it a potential tool for the diagnosis of exocrine and endocrine-related diseases.

  19. Microscopic techniques bridging between nanoscale and microscale with an atomically sharpened tip - field ion microscopy/scanning probe microscopy/ scanning electron microscopy.

    PubMed

    Tomitori, Masahiko; Sasahara, Akira

    2014-11-01

    to extend a model sample prepared for the microscopies towards a microscale sample while keeping the intrinsic properties found by the microscopies.In this study we present our trial of developing microscopic combined instruments among FIM, field emission microscopy (FEM), STM, AFM and scanning electron microscopy (SEM), in which we prepared and characterized the tips for the SPM, and in addition, the sample preparation to take a correlation between nanoscale and microscale properties of functional materials. Recently, we developed a simple sample preparation method of a rutile single crystal TiO2 covered with an epitaxially-grown monolayer of SiO2 by annealing the crystals in a furnace at high temperatures in air; the crystal samples were placed into a quartz container in the furnace [1]. The vapor of SiO evaporated from the quartz container were adsorbed on the crystal while the crystal surfaces being fully oxidized in air. The SiO2-TiO2 composite systems are promising to protect catalytic TiO2 performance; the photo-catalytic activity is kept by coating with hard and stable SiO2 layers and to extend the lifetime of water super-hydrophilicity even in dark, though understanding of their properties is insufficient due to the lack of techniques to fabricate a well-characterized system on a nanoscale to conduct control experiments. The SiO2 overlayers were observed by low energy electron diffraction (LEED) in vacuum and frequency-modulation (FM) AFM in water [1,2], and water contact angles (WCA) were measured [2]. Although the WCA measurement seems a classic characterization, this method possesses a high potential to make a bridge by controlling the environmental conditions. We will discuss the details.

  20. Rapid scan electron paramagnetic resonance at 1.0 GHz of defect centers in γ-irradiated organic solids.

    PubMed

    Shi, Yilin; Rinard, George A; Quine, Richard W; Eaton, Sandra S; Eaton, Gareth R

    2016-02-01

    The radicals in six (60)Co γ-irradiated solids: malonic acid, glycylglycine, 2,6 di-t-butyl 4-methyl phenol, L-alanine, dimethyl malonic acid, and 2-amino isobutyric acid, were studied by rapid scan electron paramagnetic resonance at L-band (1.04 GHz) using a customized Bruker Elexsys spectrometer and a locally-designed dielectric resonator. Sinusoidal scans with widths up to 18.2 mT were generated with the recently described coil driver and Litz wire coils. Power saturation curves showed that the rapid scan signals saturated at higher powers than did conventional continuous wave signals. The rapid scan data were deconvolved and background subtracted to obtain absorption spectra. For the same data acquisition time the signal-to-noise for the absorption spectra obtained in rapid scans were 23 to 37 times higher than for first-derivative spectra obtained by conventional continuous wave electron paramagnetic resonance.

  1. Rapid scan electron paramagnetic resonance at 1.0 GHz of defect centers in γ-irradiated organic solids

    PubMed Central

    Shi, Yilin; Rinard, George A.; Quine, Richard W.; Eaton, Sandra S.; Eaton, Gareth R.

    2016-01-01

    The radicals in six 60Co γ-irradiated solids: malonic acid, glycylglycine, 2,6 di-t-butyl 4-methyl phenol, L-alanine, dimethyl malonic acid, and 2-amino isobutyric acid, were studied by rapid scan electron paramagnetic resonance at L-band (1.04 GHz) using a customized Bruker Elexsys spectrometer and a locally-designed dielectric resonator. Sinusoidal scans with widths up to 18.2 mT were generated with the recently described coil driver and Litz wire coils. Power saturation curves showed that the rapid scan signals saturated at higher powers than did conventional continuous wave signals. The rapid scan data were deconvolved and background subtracted to obtain absorption spectra. For the same data acquisition time the signal-to-noise for the absorption spectra obtained in rapid scans were 23 to 37 times higher than for first-derivative spectra obtained by conventional continuous wave electron paramagnetic resonance. PMID:26834505

  2. Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope

    PubMed Central

    Hieckmann, Ellen; Nacke, Markus; Allardt, Matthias; Bodrov, Yury; Chekhonin, Paul; Skrotzki, Werner; Weber, Jörg

    2016-01-01

    Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared. PMID:27285177

  3. Nanoscale imaging of whole cells using a liquid enclosure and a scanning transmission electron microscope.

    PubMed

    Peckys, Diana B; Veith, Gabriel M; Joy, David C; de Jonge, Niels

    2009-12-14

    Nanoscale imaging techniques are needed to investigate cellular function at the level of individual proteins and to study the interaction of nanomaterials with biological systems. We imaged whole fixed cells in liquid state with a scanning transmission electron microscope (STEM) using a micrometer-sized liquid enclosure with electron transparent windows providing a wet specimen environment. Wet-STEM images were obtained of fixed E. coli bacteria labeled with gold nanoparticles attached to surface membrane proteins. Mammalian cells (COS7) were incubated with gold-tagged epidermal growth factor and fixed. STEM imaging of these cells resulted in a resolution of 3 nm for the gold nanoparticles. The wet-STEM method has several advantages over conventional imaging techniques. Most important is the capability to image whole fixed cells in a wet environment with nanometer resolution, which can be used, e.g., to map individual protein distributions in/on whole cells. The sample preparation is compatible with that used for fluorescent microscopy on fixed cells for experiments involving nanoparticles. Thirdly, the system is rather simple and involves only minimal new equipment in an electron microscopy (EM) laboratory.

  4. Acquisition of a High Resolution Field Emission Scanning Electron Microscope for the Analysis of Returned Samples

    NASA Technical Reports Server (NTRS)

    Nittler, Larry R.

    2003-01-01

    This grant furnished funds to purchase a state-of-the-art scanning electron microscope (SEM) to support our analytical facilities for extraterrestrial samples. After evaluating several instruments, we purchased a JEOL 6500F thermal field emission SEM with the following analytical accessories: EDAX energy-dispersive x-ray analysis system with fully automated control of instrument and sample stage; EDAX LEXS wavelength-dispersive x-ray spectrometer for high sensitivity light-element analysis; EDAX/TSL electron backscatter diffraction (EBSD) system with software for phase identification and crystal orientation mapping; Robinson backscatter electron detector; and an in situ micro-manipulator (Kleindiek). The total price was $550,000 (with $150,000 of the purchase supported by Carnegie institution matching funds). The microscope was delivered in October 2002, and most of the analytical accessories were installed by January 2003. With the exception of the wavelength spectrometer (which has been undergoing design changes) everything is working well and the SEM is in routine use in our laboratory.

  5. Improved depth of field in the scanning electron microscope derived from through-focus image stacks.

    PubMed

    Boyde, Alan

    2004-01-01

    The depth of field limit in the scanning electron microscope (SEM) can be overcome by recording stacks of through-focus images (as in conventional and confocal optical microscopy) which are postprocessed to generate an all-in-focus image. Images are recorded under constant electron optical conditions by mechanical Z-axis movement of the sample. This gives rise to a change in magnification through the stack due to the perspective projection of the SEM image. Calculation of the necessary scaling as well as the derivation of best focus information at every patch in the image--and a contour map function derived from the selected patch depths--are incorporated in a new software package (Auto-Montage Pro). The utility of these procedures is demonstrated with examples from the study of human osteoporotic bone, where results show uncoupling of resorption and formation. The procedure can be combined with pseudo-colour coding for the direction of apparent illumination when using backscattered electron (BSE) detectors in contrasting positions.

  6. Magnetic lens apparatus for use in high-resolution scanning electron microscopes and lithographic processes

    SciTech Connect

    Crewe, A.V.

    2000-04-18

    Disclosed are lens apparatus in which a beam of charged particles is brought to a focus by means of a magnetic field, the lens being situated behind the target position. In illustrative embodiments, a lens apparatus is employed in a scanning electron microscope as the sole lens for high-resolution focusing of an electron beam, and in particular, an electron beam having an accelerating voltage of from about 10 to about 30,000 V. In one embodiment, the lens apparatus comprises an electrically-conducting coil arranged around the axis of the beam and a magnetic pole piece extending along the axis of the beam at least within the space surrounded by the coil. In other embodiments, the lens apparatus comprises a magnetic dipole or virtual magnetic monopole fabricated from a variety of materials, including permanent magnets, superconducting coils, and magnetizable spheres and needles contained within an energy-conducting coil. Multiple-array lens apparatus are also disclosed for simultaneous and/or consecutive imaging of multiple images on single or multiple specimens. The invention further provides apparatus, methods, and devices useful in focusing charged particle beams for lithographic processes.

  7. Direct imaging of defect formation in strained organic flexible electronics by Scanning Kelvin Probe Microscopy

    NASA Astrophysics Data System (ADS)

    Cramer, Tobias; Travaglini, Lorenzo; Lai, Stefano; Patruno, Luca; de Miranda, Stefano; Bonfiglio, Annalisa; Cosseddu, Piero; Fraboni, Beatrice

    2016-12-01

    The development of new materials and devices for flexible electronics depends crucially on the understanding of how strain affects electronic material properties at the nano-scale. Scanning Kelvin-Probe Microscopy (SKPM) is a unique technique for nanoelectronic investigations as it combines non-invasive measurement of surface topography and surface electrical potential. Here we show that SKPM in non-contact mode is feasible on deformed flexible samples and allows to identify strain induced electronic defects. As an example we apply the technique to investigate the strain response of organic thin film transistors containing TIPS-pentacene patterned on polymer foils. Controlled surface strain is induced in the semiconducting layer by bending the transistor substrate. The amount of local strain is quantified by a mathematical model describing the bending mechanics. We find that the step-wise reduction of device performance at critical bending radii is caused by the formation of nano-cracks in the microcrystal morphology of the TIPS-pentacene film. The cracks are easily identified due to the abrupt variation in SKPM surface potential caused by a local increase in resistance. Importantly, the strong surface adhesion of microcrystals to the elastic dielectric allows to maintain a conductive path also after fracture thus providing the opportunity to attenuate strain effects.

  8. Nanoscale imaging of whole cells using a liquid enclosure and a scanning transmission electron microscopy

    SciTech Connect

    De Jonge, Niels; Peckys, Diana B; Veith, Gabriel M; Joy, David Charles

    2009-01-01

    Nanoscale imaging techniques are needed to investigate cellular function at the level of individual proteins and to study the interaction of nanomaterials with biological systems. We imaged whole fixed cells in liquid state with a scanning transmission electron microscope (STEM) using a micrometer-sized liquid enclosure with electron transparent windows providing a wet specimen environment. Wet-STEM images were obtained of fixed E. coli bacteria labeled with gold nanoparticles attached to surface membrane proteins. Mammalian cells (COS7) were incubated with gold-tagged epidermal growth factor and fixed. STEM imaging of these cells resulted in a resolution of 3 nm for the gold nanoparticles. The wet-STEM method has several advantages over conventional imaging techniques. Most important is the capability to image whole fixed cells in a wet environment with nanometer resolution, which can be used, e.g., to map individual protein distributions in/on whole cells. The sample preparation is compatible with that used for fluorescent microscopy on fixed cells for experiments involving nanoparticles. Thirdly, the system is rather simple and involves only minimal new equipment in an electron microscopy (EM) laboratory.

  9. Atomic-scale imaging and spectroscopy for in situ liquid scanning transmission electron microscopy.

    PubMed

    Jungjohann, Katherine L; Evans, James E; Aguiar, Jeffery A; Arslan, Ilke; Browning, Nigel D

    2012-06-01

    Observation of growth, synthesis, dynamics, and electrochemical reactions in the liquid state is an important yet largely unstudied aspect of nanotechnology. The only techniques that can potentially provide the insights necessary to advance our understanding of these mechanisms is simultaneous atomic-scale imaging and quantitative chemical analysis (through spectroscopy) under environmental conditions in the transmission electron microscope. In this study we describe the experimental and technical conditions necessary to obtain electron energy loss (EEL) spectra from a nanoparticle in colloidal suspension using aberration-corrected scanning transmission electron microscopy (STEM) combined with the environmental liquid stage. At a fluid path length below 400 nm, atomic resolution images can be obtained and simultaneous compositional analysis can be achieved. We show that EEL spectroscopy can be used to quantify the total fluid path length around the nanoparticle and demonstrate that characteristic core-loss signals from the suspended nanoparticles can be resolved and analyzed to provide information on the local interfacial chemistry with the surrounding environment. The combined approach using aberration-corrected STEM and EEL spectra with the in situ fluid stage demonstrates a plenary platform for detailed investigations of solution-based catalysis.

  10. Scanning electron acoustic microscopy of residual stresses in ceramics - Theory and experiment

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Qian, Menglu

    1992-01-01

    The paper presents a three-dimensional mathematical model of signal generation and contrast in brittle materials and uses the model to simulate the effect of residual stress fields on the scanning electron acoustic microscopy (SEAM)-generated electron acoustic signal. According to the model, a positive (tensile) strain produces an increase in the output signal, whereas a negative (compressive) strain produces a decrease in the ouput signal. Dark field contrast conditions occur at a chopping frequency at which V2 - V1 is greater than 0 (where V2 = V is the SEAM output in a region of residual stresses, and V1 is the output in a stress-free region of the sample). Under ideal conditions (maximum contrast) V1 approaches zero. It was found that tensile strains of the order 0.2-0.3 percent, possible in brittle materials, would produce a variation of the acoustic output signal of the order 10 nV (about 1 percent), well within the image contrast and signal processing capability of the SEAM electronics.

  11. Closed-cell foam skin thickness measurement using a scanning electron microscope.

    PubMed

    Todd, Clifford S; Kuznetsova, Valentina

    2011-10-01

    Closed cell polymer foam skin thickness can be assessed by taking backscatter electron (BSE) images in a scanning electron microscope (SEM) at a series of accelerating voltages. Under a given set of experimental conditions, the electron beam mostly passes through thin polymer skin cell walls. That cell appears dark compared to adjacent thicker-skinned cells. Higher accelerating voltages lead to a thicker skin being penetrated. Monte Carlo modeling of beam-sample interactions indicates that at 5 keV, skin less than ∼0.5 μm in thickness will appear dark, whereas imaging at 30 keV allows skin thicknesses up to ∼4 μm to be identified. The distribution of skin thickness can be assessed over square millimeters of foam surface in this manner. Qualitative comparisons of the skin thicknesses of samples can be made with a simple visual inspection of the images. A semiquantitative comparison is possible by applying image analysis. The proposed method is applied to two example foams. Characterizing foam skin thickness by this method is possible using any SEM that is capable of collecting useful BSE images over a range of accelerating voltages. Imaging in low vacuum, where an electrically conductive metal coating is not required, leads to more sensitivity in skin thickness characterization.

  12. Three-dimensional machining of carbon nanotube forests using water-assisted scanning electron microscope processing

    SciTech Connect

    Rajabifar, Bahram; Maschmann, Matthew R.; Kim, Sanha; Hart, A. John; Slinker, Keith; Ehlert, Gregory J.

    2015-10-05

    We demonstrate that vertically aligned carbon nanotubes (CNTs) can be precisely machined in a low pressure water vapor ambient using the electron beam of an environmental scanning electron microscope. The electron beam locally damages the irradiated regions of the CNT forest and also dissociates the water vapor molecules into reactive species including hydroxyl radicals. These species then locally oxidize the damaged region of the CNTs. The technique offers material removal capabilities ranging from selected CNTs to hundreds of cubic microns. We study how the material removal rate is influenced by the acceleration voltage, beam current, dwell time, operating pressure, and CNT orientation. Milled cuts with depths between 0–100 microns are generated, corresponding to a material removal rate of up to 20.1 μm{sup 3}/min. The technique produces little carbon residue and does not disturb the native morphology of the CNT network. Finally, we demonstrate direct machining of pyramidal surfaces and re-entrant cuts to create freestanding geometries.

  13. Image-based autonomous micromanipulation system for arrangement of spheres in a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Kasaya, Takeshi; Miyazaki, Hideki T.; Saito, Shigeki; Koyano, Koichi; Yamaura, Tomio; Sato, Tomomasa

    2004-06-01

    The micromanipulation technique in a scanning electron microscope (SEM) has been attracting interest as a technique to produce microstructures such as three-dimensional photonic crystals or advanced high-density electronic circuits. However, it is difficult to fabricate a large-scale structure or to conduct a systematic experiment using numbers of structures, as long as we rely on manually operated micromanipulation. In this study, we constructed an automatic system which arranges 10-μm-sized microspheres into a given two-dimensional pattern in a SEM. The spheres are picked up by touching with the center of the planar tip of a probe (needle), and placed on the substrate by moving the contact point to the edge of the tip and inclining the probe. The positions of the probe and the spheres are visually recognized from the SEM image from above and the optical microscope image from the side. The generalized Hough transform, which can robustly detect arbitrary shape from the edge fragments, is employed for the image recognition. Contact force information obtained by a force sensor with a resolution of 14 μN is also utilized for the control. Completely automatic rearrangement of randomly sprinkled metal spheres with a diameter of 30 μm into arbitrary patterns was successfully demonstrated. Autonomous micromanipulation technique under the observation of a SEM would contribute not merely to laboratories but also to the opto-electronics industry.

  14. Magnetic lens apparatus for use in high-resolution scanning electron microscopes and lithographic processes

    DOEpatents

    Crewe, Albert V.

    2000-01-01

    Disclosed are lens apparatus in which a beam of charged particlesis brought to a focus by means of a magnetic field, the lens being situated behind the target position. In illustrative embodiments, a lens apparatus is employed in a scanning electron microscopeas the sole lens for high-resolution focusing of an electron beam, and in particular, an electron beam having an accelerating voltage of from about 10 to about 30,000 V. In one embodiment, the lens apparatus comprises an electrically-conducting coil arranged around the axis of the beam and a magnetic pole piece extending along the axis of the beam at least within the space surrounded by the coil. In other embodiments, the lens apparatus comprises a magnetic dipole or virtual magnetic monopole fabricated from a variety of materials, including permanent magnets, superconducting coils, and magnetizable spheres and needles contained within an energy-conducting coil. Multiple-array lens apparatus are also disclosed for simultaneous and/or consecutive imaging of multiple images on single or multiple specimens. The invention further provides apparatus, methods, and devices useful in focusing charged particle beams for lithographic processes.

  15. Simultaneous measurement of lateral and vertical size of nanoparticles using transmission scanning electron microscopy (TSEM)

    NASA Astrophysics Data System (ADS)

    Buhr, E.; Bug, M. U.; Bergmann, D.; Cizmar, P.; Frase, C. G.

    2017-03-01

    A scanning electron microscope operated in transmission mode (TSEM) enables both the measurement of the lateral and vertical size (thickness) of nanoparticles. The lateral size is measured with a previously described technique where the particle boundary is determined in the TSEM image. Particle thickness is deduced from the TSEM signal level measured at the centre of the particle, which requires prior knowledge of the expected TSEM signal level. We applied different and well-known Monte-Carlo based simulation tools (Geant4 and MCSEM) to describe the electron diffusion in solid states and to calculate the expected TSEM signals taking into account particle and instrument properties. The simulation results of the different simulation models differ slightly revealing current limits of small-angle and low-energy electron scattering modelling in solid states. Nonetheless, the method allows one to correlate lateral and vertical particle thickness and thus to obtain additional information about the 3D morphology of nanoparticles. We demonstrate the method for silica particles with sizes in the range of about 10 nm–100 nm.

  16. Atomic-Scale Imaging and Spectroscopy for In Situ Liquid Scanning Transmission Electron Microscopy

    SciTech Connect

    Jungjohann, K. L.; Evans, James E.; Aguiar, Jeff; Arslan, Ilke; Browning, Nigel D.

    2012-06-04

    Observation of growth, synthesis, dynamics and electrochemical reactions in the liquid state is an important yet largely unstudied aspect of nanotechnology. The only techniques that can potentially provide the insights necessary to advance our understanding of these mechanisms is simultaneous atomic-scale imaging and quantitative chemical analysis (through spectroscopy) under environmental conditions in the transmission electron microscope (TEM). In this study we describe the experimental and technical conditions necessary to obtain electron energy loss (EEL) spectra from a nanoparticle in colloidal suspension using aberration corrected scanning transmission electron microscopy (STEM) combined with the environmental liquid stage. At a fluid path length below 400 nm, atomic resolution images can be obtained and simultaneous compositional analysis can be achieved. We show that EEL spectroscopy can be used to quantify the total fluid path length around the nanoparticle, and demonstrate characteristic core-loss signals from the suspended nanoparticles can be resolved and analyzed to provide information on the local interfacial chemistry with the surrounding environment. The combined approach using aberration corrected STEM and EEL spectra with the in situ fluid stage demonstrates a plenary platform for detailed investigations of solution based catalysis and biological research.

  17. Direct imaging of defect formation in strained organic flexible electronics by Scanning Kelvin Probe Microscopy

    PubMed Central

    Cramer, Tobias; Travaglini, Lorenzo; Lai, Stefano; Patruno, Luca; de Miranda, Stefano; Bonfiglio, Annalisa; Cosseddu, Piero; Fraboni, Beatrice

    2016-01-01

    The development of new materials and devices for flexible electronics depends crucially on the understanding of how strain affects electronic material properties at the nano-scale. Scanning Kelvin-Probe Microscopy (SKPM) is a unique technique for nanoelectronic investigations as it combines non-invasive measurement of surface topography and surface electrical potential. Here we show that SKPM in non-contact mode is feasible on deformed flexible samples and allows to identify strain induced electronic defects. As an example we apply the technique to investigate the strain response of organic thin film transistors containing TIPS-pentacene patterned on polymer foils. Controlled surface strain is induced in the semiconducting layer by bending the transistor substrate. The amount of local strain is quantified by a mathematical model describing the bending mechanics. We find that the step-wise reduction of device performance at critical bending radii is caused by the formation of nano-cracks in the microcrystal morphology of the TIPS-pentacene film. The cracks are easily identified due to the abrupt variation in SKPM surface potential caused by a local increase in resistance. Importantly, the strong surface adhesion of microcrystals to the elastic dielectric allows to maintain a conductive path also after fracture thus providing the opportunity to attenuate strain effects. PMID:27910889

  18. Direct imaging of defect formation in strained organic flexible electronics by Scanning Kelvin Probe Microscopy.

    PubMed

    Cramer, Tobias; Travaglini, Lorenzo; Lai, Stefano; Patruno, Luca; de Miranda, Stefano; Bonfiglio, Annalisa; Cosseddu, Piero; Fraboni, Beatrice

    2016-12-02

    The development of new materials and devices for flexible electronics depends crucially on the understanding of how strain affects electronic material properties at the nano-scale. Scanning Kelvin-Probe Microscopy (SKPM) is a unique technique for nanoelectronic investigations as it combines non-invasive measurement of surface topography and surface electrical potential. Here we show that SKPM in non-contact mode is feasible on deformed flexible samples and allows to identify strain induced electronic defects. As an example we apply the technique to investigate the strain response of organic thin film transistors containing TIPS-pentacene patterned on polymer foils. Controlled surface strain is induced in the semiconducting layer by bending the transistor substrate. The amount of local strain is quantified by a mathematical model describing the bending mechanics. We find that the step-wise reduction of device performance at critical bending radii is caused by the formation of nano-cracks in the microcrystal morphology of the TIPS-pentacene film. The cracks are easily identified due to the abrupt variation in SKPM surface potential caused by a local increase in resistance. Importantly, the strong surface adhesion of microcrystals to the elastic dielectric allows to maintain a conductive path also after fracture thus providing the opportunity to attenuate strain effects.

  19. New insights on ion track morphology in pyrochlores by aberration corrected scanning transmission electron microscopy

    SciTech Connect

    Sachan, Ritesh; Zhang, Yanwen; Ou, Xin; Trautmann, Christina; Chisholm, Matthew F.; Weber, William J.

    2016-12-13

    Here we demonstrate the enhanced imaging capabilities of an aberration corrected scanning transmission electron microscope to advance the understanding of ion track structure in pyrochlore structured materials (i.e., Gd2Ti2O7 and Gd2TiZrO7). Track formation occurs due to the inelastic transfer of energy from incident ions to electrons, and atomic-level details of track morphology as a function of energy-loss are revealed in the present work. A comparison of imaging details obtained by varying collection angles of detectors is discussed in the present work. A quantitative analysis of phase identification using high-angle annular dark field imaging is performed on the ion tracks. Finally, a novel 3-dimensional track reconstruction method is provided that is based on depth dependent imaging of the ion tracks. The technique is used in extracting the atomic-level details of nanoscale features, such as the disordered ion tracks, which are embedded in relatively thicker matrix. Another relevance of the method is shown by measuring the tilt of the ion tracks relative to the electron beam incidence that helps in knowing the structure and geometry of ion tracks quantitatively.

  20. New insights on ion track morphology in pyrochlores by aberration corrected scanning transmission electron microscopy

    DOE PAGES

    Sachan, Ritesh; Zhang, Yanwen; Ou, Xin; ...

    2016-12-13

    Here we demonstrate the enhanced imaging capabilities of an aberration corrected scanning transmission electron microscope to advance the understanding of ion track structure in pyrochlore structured materials (i.e., Gd2Ti2O7 and Gd2TiZrO7). Track formation occurs due to the inelastic transfer of energy from incident ions to electrons, and atomic-level details of track morphology as a function of energy-loss are revealed in the present work. A comparison of imaging details obtained by varying collection angles of detectors is discussed in the present work. A quantitative analysis of phase identification using high-angle annular dark field imaging is performed on the ion tracks. Finally,more » a novel 3-dimensional track reconstruction method is provided that is based on depth dependent imaging of the ion tracks. The technique is used in extracting the atomic-level details of nanoscale features, such as the disordered ion tracks, which are embedded in relatively thicker matrix. Another relevance of the method is shown by measuring the tilt of the ion tracks relative to the electron beam incidence that helps in knowing the structure and geometry of ion tracks quantitatively.« less

  1. Studying Dynamic Processes of Nano-sized Objects in Liquid using Scanning Transmission Electron Microscopy.

    PubMed

    Hermannsdörfer, Justus; de Jonge, Niels

    2017-02-05

    Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a microfluidic chamber assembled in the specimen holder for Transmission Electron Microscopy (TEM) and STEM. The microfluidic system consists of two silicon microchips supporting thin Silicon Nitride (SiN) membrane windows. This article describes the basic steps of sample loading and data acquisition. Most important of all is to ensure that the liquid compartment is correctly assembled, thus providing a thin liquid layer and a vacuum seal. This protocol also includes a number of tests necessary to perform during sample loading in order to ensure correct assembly. Once the sample is loaded in the electron microscope, the liquid thickness needs to be measured. Incorrect assembly may result in a too-thick liquid, while a too-thin liquid may indicate the absence of liquid, such as when a bubble is formed. Finally, the protocol explains how images are taken and how dynamic processes can be studied. A sample containing AuNPs is imaged both in pure water and in saline.

  2. Skeletal growth phases of the cold-water coral Lophelia pertusa shown by scanning electron microscope and electron backscatter diffraction

    NASA Astrophysics Data System (ADS)

    Mouchi, Vincent; Vonlanthen, Pierre; Verrecchia, Eric P.; Crowley, Quentin G.

    2016-04-01

    Lophelia pertusa is a cold-water coral, which may form reefs by the association of multiple coralites within which a polyp lives. Each individual polyp builds an aragonite skeleton by an initial phase of early mineralization (traditionally referred to as centres of calcification) from which aragonite fibres grow in thickening deposits. The skeleton wall features successive optically opaque and translucent bands previously attributed to different regimes of growth as either uniform in crystal orientation (translucent bands) or with a chaotic organization (opaque bands). The processes involved in any organizational changes are still unknown. Microlayers in the coral wall, which represent separate periods of skeletal growth, have been recently identified and described. These growth patterns are readily visible under scanning electron microscope (SEM) after etching in dilute formic acid, but they do not necessarily form continuously visible structures. Here we present high quality SEM images and electron backscatter diffraction (EBSD) maps to study aragonite fibre orientation across the wall of L. pertusa. Both microlayers and opaque and translucent bands are compared to the crystallographic orientation of the aragonite fibres. EBSD maps and SEM images indicate that aragonite fibres do not exhibit a chaotic orientation, even in opaque bands. The absence of continuity of microlayers is partially explained by an association of multiple crystallographic preferred orientations of aragonite fibres. In the case of L. pertusa, careful textural characterisation is necessary prior to elemental or isotope analysis in order to select a skeletal transect representing a linear and continuous time period.

  3. Measurement of vibrational spectrum of liquid using monochromated scanning transmission electron microscopy-electron energy loss spectroscopy.

    PubMed

    Miyata, Tomohiro; Fukuyama, Mao; Hibara, Akihide; Okunishi, Eiji; Mukai, Masaki; Mizoguchi, Teruyasu

    2014-10-01

    Investigations on the dynamic behavior of molecules in liquids at high spatial resolution are greatly desired because localized regions, such as solid-liquid interfaces or sites of reacting molecules, have assumed increasing importance with respect to improving material performance. In application to liquids, electron energy loss spectroscopy (EELS) observed with transmission electron microscopy (TEM) is a promising analytical technique with the appropriate resolutions. In this study, we obtained EELS spectra from an ionic liquid, 1-ethyl-3-methylimidazolium bis (trifluoromethyl-sulfonyl) imide (C2mim-TFSI), chosen as the sampled liquid, using monochromated scanning TEM (STEM). The molecular vibrational spectrum and the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap of the liquid were investigated. The HOMO-LUMO gap measurement coincided with that obtained from the ultraviolet-visible spectrum. A shoulder in the spectrum observed ∼0.4 eV is believed to originate from the molecular vibration. From a separately performed infrared observation and first-principles calculations, we found that this shoulder coincided with the vibrational peak attributed to the C-H stretching vibration of the [C2mim(+)] cation. This study demonstrates that a vibrational peak for a liquid can be observed using monochromated STEM-EELS, and leads one to expect observations of chemical reactions or aids in the analysis of the dynamic behavior of molecules in liquid.

  4. Cytogenetic Characterization of the TM4 Mouse Sertoli Cell Line. II. Chromosome Microdissection, FISH, Scanning Electron Microscopy, and Confocal Laser Scanning Microscopy.

    PubMed

    Schmid, Michael; Guttenbach, Martina; Steinlein, Claus; Wanner, Gerhard; Houben, Andreas

    2015-01-01

    The chromosomes and interphase cell nuclei of the permanent mouse Sertoli cell line TM4 were examined by chromosome microdissection, FISH, scanning electron microscopy, and confocal laser scanning microscopy. The already known marker chromosomes m1-m5 were confirmed, and 2 new large marker chromosomes m6 and m7 were characterized. The minute heterochromatic marker chromosomes m4 and m5 were microdissected and their DNA amplified by DOP-PCR. FISH of this DNA probe on TM4 metaphase chromosomes demonstrated that the m4 and m5 marker chromosomes have derived from the centromeric regions of normal telocentric mouse chromosomes. Ectopic pairing of the m4 and m5 marker chromosomes with the centromeric region of any of the other chromosomes (centromeric associations) was apparent in ∼60% of the metaphases. Scanning electron microscopy revealed DNA-protein bridges connecting the centromeric regions of normal chromosomes and the associated m4 and m5 marker chromosomes. Interphase cell nuclei of TM4 Sertoli cells did not exhibit the characteristic morphology of Sertoli cells in the testes of adult mice as shown by fluorescence microscopy and confocal laser scanning microscopy.

  5. Quantitative Z-contrast imaging in the scanning transmission electron microscope with size-selected clusters

    NASA Astrophysics Data System (ADS)

    Wang, Z. W.; Li, Z. Y.; Park, S. J.; Abdela, A.; Tang, D.; Palmer, R. E.

    2011-08-01

    This paper describes a new approach of quantification of annular-dark-field or Z-contrast image intensity as a function of inner acceptance angle of the detector in a scanning transmission electron microscope. By using size-selected nanoclusters of Pd (Z = 46) and Au (Z = 79), it is shown experimentally that the exponent in the power law I ˜ Zα varies strongly between 1.2 and 1.8 as the collection angle changes from 14 to 103 mrad. The result is discussed in line with existing theoretical models. Factors, such as cluster size, structure, and orientation as well as the detector geometry, are also discussed for potential use of the work.

  6. Scanning electron microscopy and calcification in amelogenesis imperfecta in anterior and posterior human teeth.

    PubMed

    Sánchez-Quevedo, M C; Ceballos, G; García, J M; Rodríguez, I A; Gómez de Ferraris, M E; Campos, A

    2001-07-01

    Teeth fragments from members of a family clinically and genetically diagnosed as having amelogenesis imperfecta were studied by scanning electron microscopy and X-ray microprobe analysis to establish the morphological patterns and the quantitative concentration of calcium in the enamel of anterior (canine, incisor) and posterior (premolar and molar) teeth. The prism patterns in the enamel of teeth from both regions were parallel or irregularly decussate, with occasional filamentous prisms accompanied by small, irregularly rounded formations. Prismless enamel showed the R- and P-type patterns. Calcium levels in enamel of amelogenesis imperfecta and control teeth differed significantly between anterior and posterior teeth, indicating that the factors that influence normal mineralization in different regions of the dental arch are not altered in the process of amelogenesis imperfecta.

  7. Growth of vacuum evaporated ultraporous silicon studied with spectroscopic ellipsometry and scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Kaminska, Kate; Amassian, Aram; Martinu, Ludvik; Robbie, Kevin

    2005-01-01

    Using a combination of variable-angle spectroscopic ellipsometry and scanning electron microscopy, we investigated the scaling behavior of uniaxially anisotropic, ultraporous silicon manufactured with glancing angle deposition. We found that both the diameter of the nanocolumns and the spacing between them increase with film thickness according to a power-law relationship consistent with self-affine fractal growth. An ellipsometric model is proposed to fit the optical properties of the anisotropic silicon films employing an effective medium approximation mixture of Tauc-Lorentz oscillator and void. This study shows that the optical response of silicon films made at glancing incidence differs significantly from that of amorphous silicon prepared by other methods due to highly oriented nanocolumn formation and power-law scaling.

  8. Narrow superficial injury to rabbit aortic endothelium. The healing process as observed by scanning electron microscopy.

    PubMed

    Ramsay, M M; Walker, L N; Bowyer, D E

    1982-06-01

    A study was made of the healing of aortic endothelium in rabbits following the production of a defined superficial injury. This was induced using a fine nylon filament which removed the endothelial cells without producing significant damage to underlying structures. The morphology of the injury and subsequent repair was observed using light microscopy and scanning and transmission electron microscopy. Two forms of injury were produced (a) a longitudinal injury along the full length of the aorta which was 50-80 microns wide (about 5-8 cell widths), (b) a circumferential injury approximately 80 microns wide (about 2 cell lengths). Thirty minutes after injury the exposed tissue was almost devoid of adherent cells, but after 4 h became covered by a sparse monolayer of platelets. Occasional leukocytes were also present from 7 h after injury. Injury tracks were found to repair very quickly; re-endothelialisation being complete by 48 h and there being no sign of injury by 7 days.

  9. Osteogenesis imperfecta lethal in infancy: case report and scanning electron microscopic studies of the deciduous teeth.

    PubMed

    Levin, L S; Rosenbaum, K N; Brady, J M; Dorst, J P

    1982-12-01

    Radiologic evaluation of the skeleton and scanning electron microscopic studies of the teeth were performed on an infant boy with a lethal osteogenesis imperfecta (OI) syndrome who died at 10 mo of pneumonia. The skeletal findings included ribs that were focally expanded by fracture calluses, flat vertebral bodies, and wide limb bones. On fractured tooth surfaces, the enamel and dentin were normal as was the dentin calcification front. Although microscopic abnormalities have been noted in teeth from previously reported infants with lethal OI, a few studies also report infants with normal teeth. These differences in dental findings may indicate heterogeneity in OI lethal in infancy. Results of our study indicate that, until the primary biochemical defects in the OI syndromes are elucidated, examination of teeth from other infants with lethal OI and detailed evaluation of other clinical and skeletal features will aid in delineating heterogeneity and variation in expression in lethal OI.

  10. Atomic force microscopy and scanning electron microscopy study of MgO(110) surface faceting

    NASA Astrophysics Data System (ADS)

    Giese, D. R.; Lamelas, F. J.; Owen, H. A.; Plass, R.; Gajdardziska-Josifovska, M.

    2000-06-01

    Phosphoric- and nitric-acid etching of the MgO(110) surface generates vicinal faceting in both the <001> and <110> directions. Vacuum annealing (to 1000°C) does not introduce thermal faceting, and does not alter the chemical-etch morphology. Three types of acid-induced faceting (early-stage pits, later-stage grooves, and inverted trapezoidal pyramids) are seen as a function of etching time. Facet-angle analysis by atomic force microscopy (AFM) and scanning electron microscopy (SEM) shows the etch morphology to be vicinal, with angles in the range of 9° to 23°, not the low-energy {100} planes expected from minimization of surface energy.

  11. Imaging thiol redox status in murine tumors in vivo with rapid-scan electron paramagnetic resonance

    NASA Astrophysics Data System (ADS)

    Epel, Boris; Sundramoorthy, Subramanian V.; Krzykawska-Serda, Martyna; Maggio, Matthew C.; Tseytlin, Mark; Eaton, Gareth R.; Eaton, Sandra S.; Rosen, Gerald M.; Kao, Joseph P. Y.; Halpern, Howard J.

    2017-03-01

    Thiol redox status is an important physiologic parameter that affects the success or failure of cancer treatment. Rapid scan electron paramagnetic resonance (RS EPR) is a novel technique that has shown higher signal-to-noise ratio than conventional continuous-wave EPR in in vitro studies. Here we used RS EPR to acquire rapid three-dimensional images of the thiol redox status of tumors in living mice. This work presents, for the first time, in vivo RS EPR images of the kinetics of the reaction of 2H,15N-substituted disulfide-linked dinitroxide (PxSSPx) spin probe with intracellular glutathione. The cleavage rate is proportional to the intracellular glutathione concentration. Feasibility was demonstrated in a FSa fibrosarcoma tumor model in C3H mice. Similar to other in vivo and cell model studies, decreasing intracellular glutathione concentration by treating mice with L-buthionine sulfoximine (BSO) markedly altered the kinetic images.

  12. A conceptual thermal design study of an electronically scanned thinned array radiometer

    NASA Technical Reports Server (NTRS)

    Gould, D. C.

    1995-01-01

    This report describes conceptual thermal design study for an Electronically Scanned Thinned Array Radiometer (ESTAR). ESTAR is an instrument concept for the measurement of soil moisture from space using synthetic aperture radiometry. The thermal design goal is to minimize the orbital temperature variation of the radiometer receivers using established materials and techniques. Two design approaches have been investigated; the first uses the waveguide as a heat sink, and the second uses a nadir facing radiator on the receiver assembly. The second approach minimizes the receiver's impact on the waveguide temperatures. Predicted temperatures for all receivers are presented for the two cases indicating the transient thermal environments the receivers would experience during an orbit. In addition, the effects of the receiver heat dissipation on the waveguide temperatures are shown.

  13. Staining and embedding of human chromosomes for 3-d serial block-face scanning electron microscopy.

    PubMed

    Yusuf, Mohammed; Chen, Bo; Hashimoto, Teruo; Estandarte, Ana Katrina; Thompson, George; Robinson, Ian

    2014-12-01

    The high-order structure of human chromosomes is an important biological question that is still under investigation. Studies have been done on imaging human mitotic chromosomes using mostly 2-D microscopy methods. To image micron-sized human chromosomes in 3-D, we developed a procedure for preparing samples for serial block-face scanning electron microscopy (SBFSEM). Polyamine chromosomes are first separated using a simple filtration method and then stained with heavy metal. We show that the DNA-specific platinum blue provides higher contrast than osmium tetroxide. A two-step procedure for embedding chromosomes in resin is then used to concentrate the chromosome samples. After stacking the SBFSEM images, a familiar X-shaped chromosome was observed in 3-D.

  14. Charge contrast imaging of biomaterials in a variable pressure scanning electron microscope.

    PubMed

    Clode, Peta L

    2006-09-01

    Charge contrast imaging (CCI) is a dynamic phenomenon recently reported in insulating and semiconducting materials imaged with low vacuum or variable pressure scanning electron microscopes (SEM). Data presented in this paper illustrates that CCI can also be applied to biominerals and biological soft-tissues and that useful and unique structural information can be obtained from routine samples. Various resin-embedded samples were considered and example images from several different biomaterials are presented. Due to the diverse nature of samples that appear to exhibit charge contrast, this imaging technique has prospective application in a wide range of biological and biomedical research. This work represents the first application of CCI to biomaterials and in particular, highlights a new method for investigating the formation, structure and growth of biominerals.

  15. Statistical Characterization of Environmental Error Sources Affecting Electronically Scanned Pressure Transducers

    NASA Technical Reports Server (NTRS)

    Green, Del L.; Walker, Eric L.; Everhart, Joel L.

    2006-01-01

    Minimization of uncertainty is essential to extend the usable range of the 15-psid Electronically Scanned Pressure (ESP) transducer measurements to the low free-stream static pressures found in hypersonic wind tunnels. Statistical characterization of environmental error sources inducing much of this uncertainty requires a well defined and controlled calibration method. Employing such a controlled calibration system, several studies were conducted that provide quantitative information detailing the required controls needed to minimize environmental and human induced error sources. Results of temperature, environmental pressure, over-pressurization, and set point randomization studies for the 15-psid transducers are presented along with a comparison of two regression methods using data acquired with both 0.36-psid and 15-psid transducers. Together these results provide insight into procedural and environmental controls required for long term high-accuracy pressure measurements near 0.01 psia in the hypersonic testing environment using 15-psid ESP transducers.

  16. Statistical Characterization of Environmental Error Sources Affecting Electronically Scanned Pressure Transducers

    NASA Technical Reports Server (NTRS)

    Green, Del L.; Walker, Eric L.; Everhart, Joel L.

    2006-01-01

    Minimization of uncertainty is essential to extend the usable range of the 15-psid Electronically Scanned Pressure [ESP) transducer measurements to the low free-stream static pressures found in hypersonic wind tunnels. Statistical characterization of environmental error sources inducing much of this uncertainty requires a well defined and controlled calibration method. Employing such a controlled calibration system, several studies were conducted that provide quantitative information detailing the required controls needed to minimize environmental and human induced error sources. Results of temperature, environmental pressure, over-pressurization, and set point randomization studies for the 15-psid transducers are presented along with a comparison of two regression methods using data acquired with both 0.36-psid and 15-psid transducers. Together these results provide insight into procedural and environmental controls required for long term high-accuracy pressure measurements near 0.01 psia in the hypersonic testing environment using 15-psid ESP transducers.

  17. 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.

  18. Determination of the coalescence temperature of latexes by environmental scanning electron microscopy.

    PubMed

    Gonzalez, Edurne; Tollan, Christopher; Chuvilin, Andrey; Barandiaran, Maria J; Paulis, Maria

    2012-08-01

    A new methodology for quantitative characterization of the coalescence process of waterborne polymer dispersion (latex) particles by environmental scanning electron microscopy (ESEM) is proposed. The experimental setup has been developed to provide reproducible latex monolayer depositions, optimized contrast of the latex particles, and a reliable readout of the sample temperature. Quantification of the coalescence process under dry conditions has been performed by image processing based on evaluation of the image autocorrelation function. As a proof of concept the coalescence of two latexes with known and differing glass transition temperatures has been measured. It has been shown that a reproducibility of better than 1.5 °C can be obtained for the measurement of the coalescence temperature.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27872493

  20. 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.