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Sample records for dye scanning electron

  1. Study of Dye-Sensitized Solar Cells by Scanning Electron Micrograph Observation and Thickness Optimization of Porous TiO2 Electrodes

    Directory of Open Access Journals (Sweden)

    Seigo Ito

    2009-01-01

    Full Text Available In order to improve the photoenergy conversion efficiency of dye-sensitized solar cells (DSCs, it is important to optimize their porous TiO2 electrodes. This paper examines the surface and cross-sectional views of the electrodes using scanning electron micrography. Two types of samples for cross-sectional viewing were prepared by mechanically breaking the substrate and by using an Ar-ion etching beam. The former displays the surface of the TiO2 particles and the latter shows the cross-section of the TiO2 particles. We found interesting surface and cross-sectional structures in the scattering layer containing the 400 nm diameter particles, which have an angular and horned shape. The influence of TiO2 particle size and the thickness of the nanocrystalline-TiO2 electrode in DSCs using four kinds of sensitizing dyes (D149, K19, N719 and Z907 and two kinds of electrolytes (acetonitrile-based and ionic-liquid electrolytes are discussed in regards to conversion efficiency, which this paper aims to optimize.

  2. A fluorescence scanning electron microscope

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    Takaaki Kanemaru

    2010-01-01

    Full Text Available Fluorescence techniques are widely used in biological research to examine molecular localization, while electron microscopy can provide unique ultrastructural information. To date, correlative images from both fluorescence and electron microscopy have been obtained separately using two different instruments, i.e. a fluorescence microscope (FM and an electron microscope (EM. In the current study, a scanning electron microscope (SEM (JEOL JXA8600 M was combined with a fluorescence digital camera microscope unit and this hybrid instrument was named a fluorescence SEM (FL-SEM. In the labeling of FL-SEM samples, both Fluolid, which is an organic EL dye, and Alexa Fluor, were employed. We successfully demonstrated that the FL-SEM is a simple and practical tool for correlative fluorescence and electron microscopy.

  3. Scanning Auger Electron Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — A JEOL model 7830F field emission source, scanning Auger microscope. Specifications / Capabilities: Ultra-high vacuum (UHV), electron gun range from 0.1 kV to 25 kV,...

  4. Scanning Auger Electron Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — A JEOL model 7830F field emission source, scanning Auger microscope.Specifications / Capabilities:Ultra-high vacuum (UHV), electron gun range from 0.1 kV to 25 kV,...

  5. Scanning ultrafast electron microscopy.

    Science.gov (United States)

    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.

  6. Scanning ultrafast electron microscopy

    Science.gov (United States)

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

    2010-01-01

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

  7. Forensic Scanning Electron Microscope

    Science.gov (United States)

    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.

  8. Correlative photoactivated localization and scanning electron microscopy.

    Directory of Open Access Journals (Sweden)

    Benjamin G Kopek

    Full Text Available 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.

  9. Correlative photoactivated localization and scanning electron microscopy.

    Science.gov (United States)

    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.

  10. Field-emission scanning electron microscopy and energy-dispersive x-ray analysis to understand the role of tannin-based dyes in the degradation of historical wool textiles.

    Science.gov (United States)

    Restivo, Annalaura; Degano, Ilaria; Ribechini, Erika; Pérez-Arantegui, Josefina; Colombini, Maria Perla

    2014-10-01

    An innovative approach, combining field-emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDX) analysis, is presented to investigate the degradation mechanisms affecting tannin-dyed wool. In fact, tannin-dyed textiles are more sensitive to degradation then those dyed with other dyestuffs, even in the same conservation conditions. FESEM-EDX was first used to study a set of 48 wool specimens (artificially aged) dyed with several raw materials and mordants, and prepared according to historical dyeing recipes. EDX analysis was performed on the surface of wool threads and on their cross-sections. In addition, in order to validate the model formulated by the analysis of reference materials, several samples collected from historical and archaeological textiles were subjected to FESEM-EDX analysis. FESEM-EDX investigations enabled us to reveal the correlation between elemental composition and morphological changes. In addition, aging processes were clarified by studying changes in the elemental composition of wool from the protective cuticle to the fiber core in cross-sections. Morphological and elemental analysis of wool specimens and of archaeological and historical textiles showed that the presence of tannins increases wool damage, primarily by causing a sulfur decrease and fiber oxidation.

  11. Control on Electron Beam Scanning Track

    Institute of Scientific and Technical Information of China (English)

    王学东; 姚舜

    2004-01-01

    In order to use electron beam as a movable welding heat source and whose energy distribution along its moving trace can be controlled, a method of electron beam scanning track and scanning mode control was put forward. Based on it, the electron beam scanning track and scanning mode can be edited at will according to actual requirements, and the energy input of each point of the scanning track can be controlled. In addition, the scanning frequency and points control, real time adjusting of the scanning track etc. were explained. This method can be used in electron beam brazing, surface modification, surface heat treatment etc.

  12. A comparative microleakage evaluation of three different base materials in Class I cavity in deciduous molars in sandwich technique using dye penetration and dentin surface interface by scanning electron microscope

    Directory of Open Access Journals (Sweden)

    Babita Niranjan

    2016-01-01

    Full Text Available Introduction: A major objective in restorative dentistry is the control of marginal leakage, which may occur because of dimensional changes or lack of adaptation of restorative material to the cavity preparation. Numerous techniques have been advocated to overcome polymerization shrinkage in composite restorations. Aim and Objectives: This study investigated microleakage of three different bases under composite resin in sandwich technique using dye penetration and dentin surface interface using scanning electron microscope (SEM. Materials and Methods: Sixty extracted deciduous molars were stored in distilled water and Class I cavities with a width of about one-fourth of intercuspal distance and a depth of 0.5-1 mm below the dentino-enamel junction was prepared without bevels. In Group 1 - glass ionomer cement (GIC; Group 2 - mineral trioxide aggregate (MTA; Group 3 - Biodentine™ was placed as a base under composite. Teeth were longitudinally sectioned in two halves, through the centers of the restoration, immersed in 2% methylene blue and microleakage was evaluated under stereomicroscope and surface interface between base and dentin was evaluated under SEM. Results:Under the condition of in vitro study, less microleakage and less internal gaps were seen in Biodentine™ (0.00 ± 0.00 and 4.00 ± 1.59 group than MTA (0.00 ± 0.00 and 6.08 ± 1.82 and GIC (25.25 ± 6.57 and 14.73 ± 3.72, respectively and showed very strong positive correlation between microleakage and internal gaps. Conclusion: Biodentine™ exhibits superior marginal sealing ability as well as marginal adaptation under composite resin as compared to MTA and GIC.

  13. Electronically-Scanned Fourier-Transform Spectrometer

    Science.gov (United States)

    Breckinridge, J. B.; Ocallaghan, F. G.

    1984-01-01

    Instrument efficient, lightweight, and stable. Fourier-transform spectrometer configuration uses electronic, instead of mechanical, scanning. Configuration insensitive to vibration-induced sampling errors introduced into mechanically scanned systems.

  14. Dyeing Properties of Basofil Fiber

    Institute of Scientific and Technical Information of China (English)

    JIANG Hong; DAI Jin-jin

    2002-01-01

    The structures and properties of Basofil fiber were studied using X- rays small angle diffraction analysis,differential- scanuing calorimeter and scanning electron microscopy. Disperse dyes, acid dyes and reactive dyes had been tried for dyeing Basefil fiber. It was shown disperse dyes were superior to other ones. The two series of high temperature dyes and low temperature dyes were compared for their suitability for Basofil fiber, and their dyeing behaviors were determined.

  15. Proximity Scanning Transmission Electron Microscopy/Spectroscopy

    CERN Document Server

    Hwang, Ing-Shouh

    2016-01-01

    Here a new microscopic method is proposed to image and characterize very thin samples like few-layer materials, organic molecules, and nanostructures with nanometer or sub-nanometer resolution using electron beams of energies lower than 20 eV. The microscopic technique achieves high resolution through the proximity (or near-field) effect, as in scanning tunneling microscopy (STM), while it also allows detection of transmitted electrons for imaging and spectroscopy, as in scanning transmission electron microscopy (STEM). This proximity transmission electron microscopy (PSTEM) does not require any lens to focus the electron beam. It also allows detailed characterization of the interaction of low-energy electron with materials. PSTEM can operate in a way very similar to scanning tunneling microscopy, which provides high-resolution imaging of geometric and electronic structures of the sample surface. In addition, it allows imaging and characterization of the interior structures of the sample based on the detected...

  16. 196 Beams in a Scanning Electron Microscope

    NARCIS (Netherlands)

    Mohammadi-Gheidari, A.

    2013-01-01

    In this thesis, for the first time ever, it is demonstrated that 196 beams out of a single electron source can be finely focused onto the sample using the electron optics of a standard single beam SEM. During this PhD thesis, a multi beam scanning electron (MBSEM) was designed and built. The thesis

  17. Electronic structure of Fe- vs. Ru-based dye molecules

    DEFF Research Database (Denmark)

    Johnson, Phillip S.; Cook, Peter L.; Zegkinoglou, Ioannis;

    2013-01-01

    In order to explore whether Ru can be replaced by inexpensive Fe in dye molecules for solar cells, the differences in the electronic structure of Fe- and Ru-based dyes are investigated by X-ray absorption spectroscopy and first-principles calculations. Molecules with the metal in a sixfold...

  18. Scanning probe methods applied to molecular electronics

    OpenAIRE

    Pavliček, Niko

    2013-01-01

    Scanning probe methods on insulating films offer a rich toolbox to study electronic, structural and spin properties of individual molecules. This work discusses three issues in the field of molecular and organic electronics. A scanning tunneling microscopy (STM) head to be operated in high magnetic fields has been designed and built up. The STM head is very compact and rigid relying on a robust coarse approach mechanism. This will facilitate investigations of the spin properties of individ...

  19. Gigahertz-band electronically scanned antennas

    Science.gov (United States)

    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.

  20. Electron Donor-Acceptor Quenching and Photoinduced Electron Transfer for Coumarin Dyes.

    Science.gov (United States)

    1983-10-31

    Mechanism of cousarin photodegradation . Ithe behavior of eoiuma dyes is water ad In aqueous detergent media,. and the effsects of medism aud, additives on...D-i36 345 ELECTRON DONOR-ACCEPTOR UENCHING AND PHOTOINDUCED i/i Ai ELECTRON TRANSFER FOR COUMARIN DYES (U) BOSTON UNIY MR DEPT OF CHEMISTRY G JONES...TYPE OF REPORT & PEIOD COVERED Electron Donor-acceptor Quenching and Photo- Technical, 1/1/82-10/31/82 induced Electron Transfer for Coumarin Dyes S

  1. Scanning Electron Microscopy Sample Preparation and Imaging.

    Science.gov (United States)

    Nguyen, Jenny Ngoc Tran; Harbison, Amanda M

    2017-01-01

    Scanning electron microscopes allow us to reach magnifications of 20-130,000× and resolve compositional and topographical images with intense detail. These images are created by bombarding a sample with electrons in a focused manner to generate a black and white image from the electrons that bounce off of the sample. The electrons are detected using positively charged detectors. Scanning electron microscopy permits three-dimensional imaging of desiccated specimens or wet cells and tissues by using variable pressure chambers. SEM ultrastructural analysis and intracellular imaging supplement light microscopy for molecular profiling of prokaryotes, plants, and mammals. This chapter demonstrates how to prepare and image samples that are (a) desiccated and conductive, (b) desiccated and nonconductive but coated with an electron conductive film using a gold sputter coater, and (c) wet and maintained in a hydrated state using a Deben Coolstage.

  2. Nonlinear optical properties of natural laccaic acid dye studied using Z-scan technique

    Science.gov (United States)

    Zongo, S.; Sanusi, K.; Britton, J.; Mthunzi, P.; Nyokong, T.; Maaza, M.; Sahraoui, B.

    2015-08-01

    We have investigated the nonlinear optical properties, including the optical limiting behaviour for five different concentrations of laccaic acid dye in solution and a thin film obtained through doping in poly (methyl methacrylate) (PMMA) polymer. The experiments were performed by using single beam Z-scan technique at 532 nm with 10 ns, 10 Hz Nd:YAG laser pulses excitation. From the open-aperture Z-scan data, we derived that the laccaic dye samples exhibit strong two photon absorption (2PA). The nonlinear refractive index was determined through the closed aperture Z-scan data. The estimated absorption coefficient β2, nonlinear refractive index n2 and second order hyperpolarizability γ were found to be of the order of 10-10 m/W, 10-9 esu and 10-32 esu, respectively. The Z-scan study reveals that the natural laccaic acid dye emerges as a promising material for third order nonlinear optical devices application.

  3. Environmental scanning electron microscopy in cell biology.

    Science.gov (United States)

    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.

  4. Development of Scanning Ultrafast Electron Microscope Capability.

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Kimberlee Chiyoko [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Talin, Albert Alec [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Chandler, David W. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Michael, Joseph R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    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.

  5. Energetic materials research using scanning electron microscopy

    NARCIS (Netherlands)

    Elshout, J.J.M.H. van den; Duvalois, W.; Benedetto, G.L. Di; Bouma, R.H.B.; Heijden, A.E.D.M. van der

    2016-01-01

    A key-technique for the research of energetic materials is scanning electron microscopy. In this paper several examples are given of characterization studies on energetic materials, including a solid composite propellant formulation. Results of the characterization of energetic materials using scann

  6. Phosphogypsum surface characterisation using scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Rajković Miloš B.

    2003-01-01

    Full Text Available This paper presents the results of application of Scanning Electron Microscopy (SEM to examinations of the samples of natural gypsum and phosphogypsum. Phosphogypsum has a well developed crystalline structure, and appear in two polymorphous forms, of rombic and hexagonal shape crystals. Natural gypsum has a poorly crystalline structure. The differences in crystalline structure influence the chemical behavior of these row materials.

  7. Energetic materials research using scanning electron microscopy

    NARCIS (Netherlands)

    Elshout, J.J.M.H. van den; Duvalois, W.; Benedetto, G.L. Di; Bouma, R.H.B.; Heijden, A.E.D.M. van der

    2016-01-01

    A key-technique for the research of energetic materials is scanning electron microscopy. In this paper several examples are given of characterization studies on energetic materials, including a solid composite propellant formulation. Results of the characterization of energetic materials using

  8. Differential scanning calorimetry and fluorimetry measurements of monoclonal antibodies and reference proteins: Effect of scanning rate and dye selection.

    Science.gov (United States)

    Lang, Brian E; Cole, Kenneth D

    2017-05-01

    Differential scanning calorimetry (DSC) and differential scanning fluorimetry (DSF) were used to measure the transition temperatures of four proteins: RNase A, invertase, rituximab, and the NISTmAb (NIST Reference Material, RM 8671). The proteins were combined with several different fluorescent dyes for the DSF measurements. This study compares the results of DSC and DSF measurements of transition temperatures with different types of proteins, dye combinations, and thermal scan rates. As protein unfolding is often influenced by kinetic effects, we measured the transition temperatures of the proteins using DSC over a range of temperature scan rates and compared them to the data obtained from DSF over comparable temperature scan rates. The results when the proteins were combined with Sypro Orange(®) and bis-ANS for the DSF measurements had the best correlations with the transition temperatures determined by calorimetry. The scan rate was found to be an important variable when comparing results between DSC and DSF. The van't Hoff enthalpy changes for the transitions were calculated from the DSC data by using a non-two-state model and from the DSF values using a two-state model. The calculated van't Hoff enthalpy changes did not show a good correlation between the two methods. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:677-686, 2017. © 2017 American Institute of Chemical Engineers.

  9. Scanning electron microscopy of superficial white onychomycosis*

    Science.gov (United States)

    de Almeida Jr., Hiram Larangeira; Boabaid, Roberta Oliveira; Timm, Vitor; Silva, Ricardo Marques e; de Castro, Luis Antonio Suita

    2015-01-01

    Superficial white onychomycosis is characterized by opaque, friable, whitish superficial spots on the nail plate. We examined an affected halux nail of a 20-year-old male patient with scanning electron microscopy. The mycological examination isolated Trichophyton mentagrophytes. Abundant hyphae with the formation of arthrospores were found on the nail's surface, forming small fungal colonies. These findings showed the great capacity for dissemination of this form of onychomycosis. PMID:26560225

  10. Structure-performance correlations of organic dyes with an electron-deficient diphenylquinoxaline moiety for dye-sensitized solar cells.

    Science.gov (United States)

    Li, Sie-Rong; Lee, Chuan-Pei; Yang, Po-Fan; Liao, Chia-Wei; Lee, Mandy M; Su, Wei-Lin; Li, Chun-Ting; Lin, Hao-Wu; Ho, Kuo-Chuan; Sun, Shih-Sheng

    2014-08-04

    The high performances of dye-sensitized solar cells (DSSCs) based on seven new dyes are disclosed. Herein, the synthesis and electrochemical and photophysical properties of a series of intentionally designed dipolar organic dyes and their application in DSSCs are reported. The molecular structures of the seven organic dyes are composed of a triphenylamine group as an electron donor, a cyanoacrylic acid as an electron acceptor, and an electron-deficient diphenylquinoxaline moiety integrated in the π-conjugated spacer between the electron donor and acceptor moieties. The DSSCs based on the dye DJ104 gave the best overall cell performance of 8.06 %; the efficiency of the DSSC based on the standard N719 dye under the same experimental conditions was 8.82 %. The spectral coverage of incident photon-to-electron conversion efficiencies extends to the onset at the near-infrared region due to strong internal charge-transfer transition as well as the effect of electron-deficient diphenylquinoxaline to lower the energy gap in these organic dyes. A combined tetraphenyl segment as a hydrophobic barrier in these organic dyes effectively slows down the charge recombination from TiO2 to the electrolyte and boosts the photovoltage, comparable to their Ru(II) counterparts. Detailed spectroscopic studies have revealed the dye structure-cell performance correlations, to allow future design of efficient light-harvesting organic dyes.

  11. Dopant profiling with the scanning electron microscope

    CERN Document Server

    Elliott, S L

    2001-01-01

    This dissertation is a detailed study of dopant profiling with the scanning electron microscope (SEM) using secondary electrons. The technique has been applied to a wide variety of doped silicon, gallium arsenide and gallium nitride semiconductor test structures as well as a metal-oxide field effect transistor and several light emitting diodes. A concise set of guide-lines are provided for users of this technique, including the optimum SEM operating conditions that should be used for maximum contrast, an image manipulation procedure, and the resolution and sensitivity limits that can be expected. Dopant contrast observed with the SEM has been studied over the past few years by a number of researchers, and a theory for the contrast has evolved. This theory considers the patch fields outside the specimen to be the dominant factor determining the secondary electron intensity. In this dissertation the contrast mechanism has been further investigated by examining the contrast at different temperatures and after su...

  12. Third-order nonlinear optical properties of acid green 25 dye by Z-scan method

    Science.gov (United States)

    Jeyaram, S.; Geethakrishnan, T.

    2017-03-01

    Third-order nonlinear optical (NLO) properties of aqueous solutions of an anthraquinone dye (Acid green 25 dye, color index: 61570) have been studied by Z-scan method with a 5 mW continuous wave (CW) diode laser operating at 635 nm. The nonlinear refractive index (n2) and the absorption coefficient (β) have been evaluated respectively from the closed and open aperture Z-scan data and the values of these parameters are found to increase with increase in concentration of the dye solution. The negative sign of the observed nonlinear refractive index (n2) indicates that the aqueous solution of acid green 25 dye exhibits self-defocusing type optical nonlinearity. The mechanism of the observed nonlinear absorption (NLA) and nonlinear refraction (NLR) is attributed respectively to reverse saturable absorption (RSA) and thermal nonlinear effects. The magnitudes of n2 and β are found to be of the order of 10-7 cm2/W and 10-3 cm/W respectively. With these experimental results, the authors suggest that acid green 25 dye may have potential applications in nonlinear optics.

  13. Scanning probe microscopy studies on the adsorption of selected molecular dyes on titania

    Directory of Open Access Journals (Sweden)

    Jakub S. Prauzner-Bechcicki

    2016-11-01

    Full Text Available Titanium dioxide, or titania, sensitized with organic dyes is a very attractive platform for photovoltaic applications. In this context, the knowledge of properties of the titania–sensitizer junction is essential for designing efficient devices. Consequently, studies on the adsorption of organic dyes on titania surfaces and on the influence of the adsorption geometry on the energy level alignment between the substrate and an organic adsorbate are necessary. The method of choice for investigating the local environment of a single dye molecule is high-resolution scanning probe microscopy. Microscopic results combined with the outcome of common spectroscopic methods provide a better understanding of the mechanism taking place at the titania–sensitizer interface. In the following paper, we review the recent scanning probe microscopic research of a certain group of molecular assemblies on rutile titania surfaces as it pertains to dye-sensitized solar cell applications. We focus on experiments on adsorption of three types of prototypical dye molecules, i.e., perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA, phtalocyanines and porphyrins. Two interesting heteromolecular systems comprising molecules that are aligned with the given review are discussed as well.

  14. [Pili annulati. A scanning electron microscopy study].

    Science.gov (United States)

    Lalević-Vasić, B; Polić, D

    1988-01-01

    A case of ringed hair studied by light and electron microscopy is reported. The patient, a 20-year old girl, had been presenting with the hair abnormality since birth. At naked eye examination the hairs were dry, 6 to 7 cm long, and they showed dull and shining areas giving the scalp hair a scintillating appearance (fig. 1). Several samples of hair were taken and examined by light microscopy under white and polarized light. Hair shafts and cryo-fractured surfaces were examined by scanning electron microscopy. RESULTS. 1. Light microscopy. Lesions were found in every hair examined. There were abnormal, opaque and fusiform areas alternating with normal areas all along the hair shaft (fig. 2). The abnormal areas resulted from intracortical air-filled cavities. Fractures similar to those of trichorrhexis nodosa were found in the opaque areas of the distal parts of the hairs. 2. Scanning electron microscopy. A. Hair shaft surface. The abnormal areas showed a longitudinal, "curtain-like" folding of the cuticular cells which had punctiform depressions on their surface and worn free edges (fig. 4, 5, 6); trichorrhexis-type fractures were seen in the distal parts of the hair shafts (fig. 7, 8). Normal areas regularly presented with longitudinal, superficial, short and non-systematized depressions (fig. 9); the cuticular cells were worn, and there were places where the denuded cortex showed dissociated cortical fibres (fig. 10).(ABSTRACT TRUNCATED AT 250 WORDS)

  15. Scanning Electron Microscopy of the Presbylarynx.

    Science.gov (United States)

    Gonçalves, Tatiana Maria; Dos Santos, Daniela Carvalho; Pessin, Adriana Bueno Benito; Martins, Regina Helena Garcia

    2016-06-01

    To describe the findings on the presbylarynx under scanning electron microscopy. Cadaver study. Universidade Estadual Paulista (Botucatu, São Paulo, Brazil). Sixteen vocal folds were removed during necropsies and distributed into 2 age groups: control (n = 8; aged 30-50 years) and elderly (n = 8; aged 75-92 years). The right vocal fold was dissected, fixed in glutaraldehyde 2.5%, and prepared for scanning electron microscopy. The thickness of the epithelium was measured using a scandium morphometric digital program. In the control group, the epithelium had 5 to 7 overlapped cell layers, rare desquamation cells, and little undulation with protruding intercellular junctions. The lamina propria showed a uniform network of collagen and elastic fibers in the superficial layer. A dense network of collagen was identified in the deeper layer. In the elderly group, the epithelium was atrophic (2-3 cells), with more desquamation cells and intercellular junctions delimited by deep sulci. The epithelial thickness was lower in elderly than in controls (mean [SD], 221.64 [145.90] µm vs 41.79 [21.40] µm, respectively). The lamina propria had a dense and irregular distribution of collagen and elastic fibers in the superficial layer. In the deep layers, the collagen fibers formed a true fibrotic and rigid skeleton. Scanning electron microscopy identified several changes in the elderly larynx, differentiating it from the controls. These alterations are probably related to the aging process of the vocal folds. However, the exact interpretation of these findings requires additional studies, even to the molecular level, having the fibroblasts as targets. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.

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

    Science.gov (United States)

    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.

  17. Evaluation of scanning electron microscope resolution

    Science.gov (United States)

    Maulny, Aude; Fanget, Gilles L.

    1998-06-01

    The evaluation of Scanning Electron Microscopes (SEM) resolution through Two Dimensions Fast Fourier Transform (2D FFT) image analysis is becoming a standard. We propose an improvement of these methods with a patented technique. This new image processing is designed to extract the transfer function of the SEM from the picture and then to realize the analysis of this function. A first algorithm extracts an 'ideal' image of the sample from the 'raw' image obtained on the equipment. Then a second algorithm extracts the SEM transfer function through a comparison between the two images ('ideal' and 'raw'). Finally a third algorithm modelizes the transfer function as a two dimensions Normal function and draws out the result. The representation of the transfer function of the SEM with a Normal function allows to define the shape of an Equivalent of the Electron Beam (EEB). This EEB represents the primary electron beam altered by the interactions with the sample and the losses in the acquisition loop. It is important to outline these alterations as they limit the sharpness of the images obtained from the tool. This way of doing lessens the influence of sample parameters on the final results and thus represent more precisely the SEM Transfer Function.

  18. Scanning electron microscopy of molluscum contagiosum*

    Science.gov (United States)

    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

  19. Scanning electron microscopy of bacteria Tetrasphaera duodecadis.

    Science.gov (United States)

    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.

  20. Scanning electron microscopy of Dalkon Shield tails.

    Science.gov (United States)

    Bank, H L; Williamson, H O

    1983-09-01

    Scanning electron micrographs of Dalkon Shield tails removed from asymptomatic patients show a variety of microbes and debris throughout their entire length. Apparently, even in undamaged tails, bacterial flora thrive in the protein-rich environment within the multifilament tail. The presence of microbes in the portion of the tail beyond the double knot indicates that an alternative mechanism of microbial transport can occur. Since transient endometritis often occurs immediately after insertion of intrauterine devices, microbes may come in contact with both exposed ends of the multifilament tail and be drawn into the tail by capillary action from the uterine environment down the tail toward the double knot as well as upward from the vagina. Such microorganisms could serve as an inoculum for infection.

  1. Collection of secondary electrons in scanning electron microscopes.

    Science.gov (United States)

    Müllerová, I; Konvalina, I

    2009-12-01

    Collection of the secondary electrons in the scanning electron microscope was simulated and the results have been experimentally verified for two types of the objective lens and three detection systems. The aberration coefficients of both objective lenses as well as maximum axial magnetic fields in the specimen region are presented. Compared are a standard side-attached secondary electron detector, in which only weak electrostatic and nearly no magnetic field influence the signal trajectories in the specimen vicinity, and the side-attached (lower) and upper detectors in an immersion system with weak electrostatic but strong magnetic field penetrating towards the specimen. The collection efficiency was calculated for all three detection systems and several working distances. The ability of detectors to attract secondary electron trajectories for various initial azimuthal and polar angles was calculated, too. According to expectations, the lower detector of an immersion system collects no secondary electrons I and II emitted from the specimen and only backscattered electrons and secondary electrons III form the final image. The upper detector of the immersion system exhibits nearly 100% collection efficiency decreasing, however, with the working distance, but the topographical contrast is regrettably suppressed in its image. The collection efficiency of the standard detector is low for short working distances but increases with the same, preserving strong topographical contrast.

  2. Scanning electron microscopy physics of image formation and microanalysis

    CERN Document Server

    Reimer, Ludwig

    1998-01-01

    Scanning Electron Microscopy provides a description of the physics of electron-probe formation and of electron-specimen interations The different imaging and analytical modes using secondary and backscattered electrons, electron-beam-induced currents, X-ray and Auger electrons, electron channelling effects, and cathodoluminescence are discussed to evaluate specific contrasts and to obtain quantitative information

  3. Enhanced Electron Lifetimes in Dye-Sensitized Solar Cells Using a Dichromophoric Porphyrin: The Utility of Intermolecular Forces.

    Science.gov (United States)

    Zhao, Long; Wagner, Pawel; van der Salm, Holly; Gordon, Keith C; Mori, Shogo; Mozer, Attila J

    2015-10-07

    Electron lifetimes in dye-sensitized solar cells employing a porphyrin dye, an organic dye, a 1:1 mixture of the two dyes, and a dichromophoric dye design consisting of the two dyes using a nonconjugated linker were measured, suggesting that the dispersion force of the organic dyes has a significant detrimental effect on the electron lifetime and that the dichromophoric design can be utilized to control the effect of the dispersion force.

  4. Dental Wear: A Scanning Electron Microscope Study

    Directory of Open Access Journals (Sweden)

    Luca Levrini

    2014-01-01

    Full Text Available 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.

  5. Electron optics of multi-beam scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi-Gheidari, A., E-mail: A.M.Gheidari@tudelft.nl [Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands); Kruit, P. [Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands)

    2011-07-21

    We have developed a multi-beam scanning electron microscope (MBSEM), which delivers a square array of 196 focused beams onto a sample with a resolution and current per beam comparable to a state of the art single beam SEM. It consists of a commercially available FEI Nova-nano 200 SEM column equipped with a novel multi-electron beam source module. The key challenge in the electron optical design of the MBSEM is to minimize the off-axial aberrations of the lenses. This article addresses the electron optical design of the system and presents the result of optics simulations for a specific setting of the system. It is shown that it is possible to design a system with a theoretical axial spot size of 1.2 nm at 15 kV with a probe current of 26 pA. The off-axial aberrations for the outermost beam add up 0.8 nm, increasing the probe size to 1.5 nm.

  6. Triphenylamine-based organic dyes with julolidine as the secondary electron donor for dye-sensitized solar cells

    Science.gov (United States)

    Wu, Guohua; Kong, Fantai; Li, Jingzhe; Fang, Xiaqin; Li, Yi; Dai, Songyuan; Chen, Qianqian; Zhang, Xianxi

    2013-12-01

    Two novel donor-donor-π-conjugated-acceptor (D-D-π-A) metal-free organic dyes (JTPA1 and JTPA2) with a julolidine moiety as the secondary electron donor for dye-sensitized solar cells (DSSCs) are synthesized. Their absorption spectra, electrochemical and photovoltaic properties are extensively investigated and compared with TPA2 dye. Transient absorption measurements show that both sensitizers are quickly regenerated and the dye cations are efficiently intercepted by the redox mediator. Both dyes show good performance as DSSC photosensitizers. In particular, a DSSC using JTPA2 with rhodanine-3-acetic acid shows better photovoltaic performance with a short-circuit photocurrent density (Jsc) of 9.30 mA cm-2, an open-circuit photovoltage (Voc) of 509 mV and a fill factor (FF) of 0.68, corresponding to an overall conversion efficiency (η) of 3.2% under AM 1.5 irradiation (100 mW cm-2). Under similar test conditions, ruthenium-based N719 dye gives an efficiency of 6.7%. Compared to TPA2, the dye regeneration rate, the short-circuit photocurrent density and the conversion efficiency of JTPA2 are doubled by introducing a julolidine unit. Our findings show that the julolidine unit may be an excellent electron donor system for organic dyes harvesting solar irradiation.

  7. Density Functional Theory Study on the Electronic Structures of Oxadiazole Based Dyes as Photosensitizer for Dye Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Umer Mehmood

    2015-01-01

    Full Text Available The molecular structures and UV-visible absorption spectra of complex photosensitizers comprising oxadiazole isomers as the π-bridges were analyzed by density functional theory (DFT and time-dependent DFT. The ground state and excited state oxidation potentials, HOMOs and LUMOs energy levels, and electron injection from the dyes to semiconductor TiO2 have been computed in vacuum here. The results show that all of the dyes may potentially be good photosensitizers in DSSC. To justify the simulation basis, N3 dye was also simulated under the similar conditions. Simulated absorption spectrum, HOMO, LUMO, and band gap values of N3 were compared with the experimental values. We also computed the electronic structure properties and absorption spectra of dye/(TiO28 systems to elucidate the electron injection efficiency at the interface. This work is expected to give proper orientation for experimental synthesis.

  8. Low Energy Scanned Electron-Beam Dose Distribution in Thin Layers

    DEFF Research Database (Denmark)

    McLaughlin, W. L.; Hjortenberg, P. E.; Pedersen, Walther Batsberg

    1975-01-01

    Thin radiochromic dye film dosimeters, calibrated by means of calorimetry, make possible the determination of absorbed-dose distributions due to low-energy scanned electron beam penetrations in moderately thin coatings and laminar media. For electrons of a few hundred keV, calibrated dosimeters...... of about 30–60 μm thickness may be used in stacks or interleaved between layers of materials of interest and supply a sufficient number of experimental data points throughout the depth of penetration of electrons to provide a depth-dose curve. Depth doses may be resolved in various polymer layers...... on different backings (wood, aluminum, and iron) for scanned electron beams (Emax = 400 keV) having a broad energy spectrum and diffuse incidence, such as those used in radiation curing of coatings, textiles, plastics, etc. Theoretical calculations of such distributions of energy depositions are relatively...

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

    Science.gov (United States)

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

    2017-10-01

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

  10. Applications of orientation mapping by scanning and transmission electron microscopy

    DEFF Research Database (Denmark)

    Juul Jensen, D.

    1997-01-01

    The potentials of orientation mapping techniques (in the following referred to as OIM) for studies of thermomechanical processes are analysed. Both transmission electron microscopy (TEM) and scanning electron microscopy (SEM) based OIM techniques are considered. Among the thermomechanical processes...

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

    Science.gov (United States)

    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.

  12. A MONTE CARLO SIMULATION OF SECONDARY ELECTRON AND BACKSCATTERED ELECTRON IMAGES IN SCANNING ELECTRON MICROSCOPY

    Institute of Scientific and Technical Information of China (English)

    H.M. Li; Z.J. Ding

    2005-01-01

    A new parallel Monte Carlo simulation method of secondary electron (SE) and backscattered electron images (BSE) of scanning electron microscopy (SEM) for a complex geometric structure has been developed. This paper describes briefly the simulation method and the modification to the conventional sampling method for the step length. Example simulation results have been obtained for several artificial structures.

  13. System and method for compressive scanning electron microscopy

    Science.gov (United States)

    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.

  14. Automated Scanning Electron Microscopy Analysis of Sampled Aerosol

    DEFF Research Database (Denmark)

    Bluhme, Anders Brostrøm; Kling, Kirsten; Mølhave, Kristian

    development of an automated software-based analysis of aerosols using Scanning Electron Microscopy (SEM) and Scanning Transmission Electron Microscopy (STEM) coupled with Energy-Dispersive X-ray Spectroscopy (EDS). The automated analysis will be capable of providing both detailed physical and chemical single...

  15. Electron-beam-assisted Scanning Tunneling Microscopy Of Insulating Surfaces

    CERN Document Server

    Bullock, E T

    2000-01-01

    Insulating materials are widely used in electronic devices. Bulk insulators and insulating films pose unique challenges for high resolution study since most commonly used charged particle surface analysis techniques are incompatible with insulating surfaces and materials. A, method of performing scanning tunneling microscopy (STM) on insulating surfaces has been investigated. The method is referred to as electron-beam assisted scanning tunneling microscopy (e-BASTM). It is proposed that by coupling the STM and the scanning electron microscopy (SEM) as one integrated device, that insulating materials may be studied, obtaining both high spatial resolution, and topographic and electronic resolution. The premise of the technique is based on two physical consequences of the interaction of an energetic electron beam (PE) with a material. First, when an electron beam is incident upon a material, low level material electrons are excited into conduction band states. For insulators, with very high secondary electron yi...

  16. Image Resolution in Scanning Transmission Electron Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Picosecond electron injection dynamics in dye-sensitized oxides in the presence of electrolyte

    NARCIS (Netherlands)

    Pijpers, J.J.H.; Ulbricht, R.; Derossi, S.; Reek, J.N.H.; Bonn, M.

    2011-01-01

    We employ time-resolved terahertz (THz) spectroscopy (TRTS) to directly monitor the picosecond dynamics of electron transfer in dye-sensitized oxides in the presence of an electrolyte phase. Understanding the time scale on which electrons are injected from the dye into the oxide phase in the presenc

  18. The electronic structure engineering of organic dye sensitizers for solar cells: The case of JK derivatives.

    Science.gov (United States)

    Zhang, Cai-Rong; Ma, Jin-Gang; Zhe, Jian-Wu; Jin, Neng-Zhi; Shen, Yu-Lin; Wu, You-Zhi; Chen, Yu-Hong; Liu, Zi-Jiang; Chen, Hong-Shan

    2015-11-05

    The design and development of novel dye sensitizers are effective method to improve the performance of dye-sensitized solar cells (DSSCs) because dye sensitizers have significant influence on photo-to-current conversion efficiency. In the procedure of dye sensitizer design, it is very important to understand how to tune their electronic structures and related properties through the substitution of electronic donors, acceptors, and conjugated bridges in dye sensitizers. Here, the electronic structures and excited-state properties of organic JK dye sensitizers are calculated by using density functional theory (DFT) and time dependent DFT methods. Based upon the calculated results, we investigated the role of different electronic donors, acceptors, and π-conjugated bridges in the modification of electronic structures, absorption properties, as well as the free energy variations for electron injection and dye regeneration. In terms of the analysis of transition configurations and molecular orbitals, the effective chromophores which are favorable for electron injection in DSSCs are addressed. Meanwhile, considering the absorption spectra and free energy variation, the promising electronic donors, π-conjugated bridges, and acceptors are presented to design dye sensitizers.

  19. Quantitative Scanning Transmission Electron Microscopy of Electronic and Nanostructured Materials

    Science.gov (United States)

    Yankovich, Andrew B.

    Electronic and nanostructured materials have been investigated using advanced scanning transmission electron microscopy (STEM) techniques. The first topic is the microstructure of Ga and Sb-doped ZnO. Ga-doped ZnO is a candidate transparent conducting oxide material. The microstructure of GZO thin films grown by MBE under different growth conditions and different substrates were examined using various electron microscopy (EM) techniques. The microstructure, prevalent defects, and polarity in these films strongly depend on the growth conditions and substrate. Sb-doped ZnO nanowires have been shown to be the first route to stable p-type ZnO. Using Z-contrast STEM, I have showed that an unusual microstructure of Sb-decorated head-to-head inversion domain boundaries and internal voids contain all the Sb in the nanowires and cause the p-type conduction. InGaN thin films and InGaN / GaN quantum wells (QW) for light emitting diodes are the second topic. Low-dose Z-contrast STEM, PACBED, and EDS on InGaN QW LED structures grown by MOCVD show no evidence for nanoscale composition variations, contradicting previous reports. In addition, a new extended defect in GaN and InGaN was discovered. The defect consists of a faceted pyramid-shaped void that produces a threading dislocation along the [0001] growth direction, and is likely caused by carbon contamination during growth. Non-rigid registration (NRR) and high-precision STEM of nanoparticles is the final topic. NRR is a new image processing technique that corrects distortions arising from the serial nature of STEM acquisition that previously limited the precision of locating atomic columns and counting the number of atoms in images. NRR was used to demonstrate sub-picometer precision in STEM images of single crystal Si and GaN, the best achieved in EM. NRR was used to measure the atomic surface structure of Pt nanoacatalysts and Au nanoparticles, which revealed new bond length variation phenomenon of surface atoms. In

  20. Scanning Electron Microscopy Study of Hair Shaft Damage Secondary to Cosmetic Treatments of the Hair.

    Science.gov (United States)

    Kaliyadan, Feroze; Gosai, B B; Al Melhim, Walid Naief; Feroze, Kaberi; Qureshi, Habib Ahmad; Ibrahim, Sayed; Kuruvilla, Joel

    2016-01-01

    Cosmetic procedures for hair, such as bleaching, dyeing, and straightening, are commonly used around the world. It has been suggested that excessive use of such procedures can cause damage to the hair shaft. We aimed to assess hair shaft changes using scanning electron microscopy (SEM) in female volunteers who frequently use hair treatment procedures such as bleaching, dyeing, or straightening. A cross-sectional, controlled study in a sample of 25 female volunteers (19 study group and 6 controls) in the age group of 18-45 years. The study group was composed of volunteers who regularly used different cosmetic hair treatment procedures such as bleaching, dyeing, and straightening (any one of these or a combination). The control group had never used any specific hair treatment procedure. The hair shaft damage as seen on SEM was assessed using a standardized scoring system and compared among the two groups statistically. The hair shafts were also examined clinically and with light microscopy. No significant differences were seen between the test and control groups with regard to normal clinical examination and light microscopy findings. A higher degree of hair shaft damage was evident under SEM in the study group as compared to the control group. This difference was statistically significant. Regular use of procedures such as bleaching, dyeing, or straightening can lead to subtle changes in the hair shaft which can be detected early by SEM.

  1. Effects of dye adsorption on the electron transport properties in ZnO-nanowire dye-sensitized solar cells

    Science.gov (United States)

    Wu, Jih-Jen; Chen, Guan-Ren; Yang, Hung-Hsien; Ku, Chen-Hao; Lai-Yuan, Jr.

    2007-05-01

    Mercurochrome and N3 dyes are employed to be the sensitizers in the ZnO-nanowire (NW) dye-sensitized solar cells (DSSCs). A lower fill factor is obtained in the N3-sensitized cell which results in comparable efficiencies in both ZnO-NW DSSCs although the N3 molecules possess a wider absorptive range for light harvesting. Electrochemical impedance spectroscopy and open-circuit photovoltage decay measurements are employed to investigate the electron transport properties in both ZnO-NW DSSCs. The results indicate that more abundant electron interfacial recombination occurs in the N3-sensitized ZnO-NW DSSC due to the higher surface trap density in the ZnO-NW photoanode after N3 dye adsorption.

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

    Science.gov (United States)

    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.

  3. Simulation study of secondary electron images in scanning ion microscopy

    CERN Document Server

    Ohya, K

    2003-01-01

    The target atomic number, Z sub 2 , dependence of secondary electron yield is simulated by applying a Monte Carlo code for 17 species of metals bombarded by Ga ions and electrons in order to study the contrast difference between scanning ion microscopes (SIM) and scanning electron microscopes (SEM). In addition to the remarkable reversal of the Z sub 2 dependence between the Ga ion and electron bombardment, a fine structure, which is correlated to the density of the conduction band electrons in the metal, is calculated for both. The brightness changes of the secondary electron images in SIM and SEM are simulated using Au and Al surfaces adjacent to each other. The results indicate that the image contrast in SIM is much more sensitive to the material species and is clearer than that for SEM. The origin of the difference between SIM and SEM comes from the difference in the lateral distribution of secondary electrons excited within the escape depth.

  4. Optical Absorption and Electron Injection of 4-(Cyanomethylbenzoic Acid Based Dyes: A DFT Study

    Directory of Open Access Journals (Sweden)

    Yuehua Zhang

    2015-01-01

    Full Text Available Density functional theory (DFT and time-dependent density functional theory (TDDFT calculations were carried out to study the ground state geometries, electronic structures, and absorption spectra of 4-(cyanomethylbenzoic acid based dyes (AG1 and AG2 used for dye-sensitized solar cells (DSSCs. The excited states properties and the thermodynamical parameters of electron injection were studied. The results showed that (a two dyes have uncoplanar structures along the donor unit and conjugated bridge space, (b two sensitizers exhibited intense absorption in the UV-Vis region, and (c the excited state oxidation potential was higher than the conduction band edge of TiO2 photoanode. As a result, a solar cell based on the 4-(cyanomethylbenzoic acid based dyes exhibited well photovoltaic performance. Furthermore, nine dyes were designed on the basis of AG1 and AG2 to improve optical response and electron injection.

  5. DFT and TD-DFT study on geometries, electronic structures and electronic absorption of some metal free dye sensitizers for dye sensitized solar cells.

    Science.gov (United States)

    Mohr, T; Aroulmoji, V; Ravindran, R Samson; Müller, M; Ranjitha, S; Rajarajan, G; Anbarasan, P M

    2015-01-25

    The geometries, electronic structures, polarizabilities and hyperpolarizabilities of 2-hydroxynaphthalene-1,4-dione (henna1), 3-(5-((1E)-2-(1,4-dihydro-1,4-dioxonaphthalen-3-yloxy) vinyl) thiophen-2-yl)-2-isocyanoacrylic acid (henna2) and anthocyanin dye sensitizers were studied based on density functional theory (DFT) using the hybrid functional B3LYP. The Ultraviolet-Visible (UV-Vis) spectrum was investigated by using a hybrid method which combines the properties and dynamics of many-body in the presence of time-dependent (TD) potentials, i.e. TDSCF-DFT (B3LYP). Features of the electronic absorption spectrum in the visible and near-UV regions were plotted and assigned based on TD-DFT calculations. Due to the absorption, bands of the metal-organic compound are n→π(*) present. The calculated results suggest that the three lowest energy excited states of the investigated dye sensitizers are due to photoinduced electron transfer processes. The interfacial electron transfer between semiconductor TiO2 electrode and dye sensitizer is owing to an electron injection process from excited dye to the semiconductor's conduction band. The role of linking the henna1 dye with a carboxylic acid via a thiophene bridge was analyzed. The results are that using a stronger π-conjugate bridge as well as a strong donator and acceptor group enhances the efficiency.

  6. Collective electronic effects in scanning probe microscopy

    Science.gov (United States)

    Passian, Ali

    The surface plasmon dispersion relations are calculated for a metal coated dielectric probe above a dielectric half space with and without metal coating. Employing prolate spheroidal coordinate system this configuration was modeled as confocal single-sheeted hyperboloids of revolution superimposed on planar domains. The involved media are characterized by frequency dependent, spatially local dielectric functions. Due to subwavelength dimensions of the region of interest, nonretarded electrodynamics is utilized to derive exact analytical expressions describing the resonant surface modes. The dispersion relations are studied as functions of the parameter that defines the hyperboloidal boundaries of the tip and the corresponding coating, and as functions of the involved coating thicknesses. Both parallel and perpendicular polarizations are considered. The results are simulated numerically and limiting cases are discussed with comparison to the Cartesian thin foil case. Using this new type of probe-substrate configuration, the surface plasmon coupling mechanism is investigated experimentally utilizing a scanning probe microscope, and the signal strength acquired by the probe is measured as a function of the distance between the probe and the sample. This is repeated at three different wavelengths of the incident p-polarized photons used to stimulate surface plasmons in the thin metal foil. The results are compared with the theory. Utilizing the prolate spheroidal coordinate system, the related and relevant problem of the Coulomb interaction of a dielectric probe tip with a uniform field existing above a semiinfinite, homogeneous dielectric substrate was studied. This is of interest in atomic force microscopy when the sample surface is electrically charged. The induced polarization surface charge density and the field distribution at the bounding surface of the dielectric medium with the geometry of a single-sheeted hyperboloid of revolution located above the dielectric

  7. Ultrafast electron and energy transfer in dye-sensitized iron oxide and oxyhydroxide nanoparticles

    DEFF Research Database (Denmark)

    Gilbert, Benjamin; Katz, Jordan E.; Huse, Nils

    2013-01-01

    –310 fs were found for all samples. Comparison between TA dynamics on uncoated and dye-sensitized hematite nanoparticles revealed the dye de-excitation pathway to consist of a competition between electron and energy transfer to the nanoparticles. We analyzed the TA data for hematite nanoparticles using...... a four-state model of the dye-sensitized system, finding electron and energy transfer to occur on the same ultrafast timescale. The interfacial electron transfer rates for iron oxides are very close to those previously reported for DCF-sensitized titanium dioxide (for which dye–oxide energy transfer...... photo-initiated interfacial electron transfer. This approach enables time-resolved study of the fate and mobility of electrons within the solid phase. However, complete analysis of the ultrafast processes following dye photoexcitation of the sensitized iron(iii) oxide nanoparticles has not been reported...

  8. Writing silica structures in liquid with scanning transmission electron microscopy.

    Science.gov (United States)

    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.

  9. Determining Hermeticity of Electron Devices by Dye Penetration

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1972-01-01

    1.1 These practices cover procedures that will normally detect and locate the sites of gross leaks in electron devices. 1.2 These procedures are suitable for use on selected parts during receiving inspection or to verify and locate leakage sites for production control. They are not quantitative; no indication of leak size can be inferred from the test. 1.3 These procedures are most suitable for use on transparent glass-encased devices; all methods are applicable to transparent parts with an internal cavity. Method A, Penetrant-Capillary, is also applicable to parts, such as terminals, end seals or base assemblies, without an internal cavity, and Method C, Penetrant-Pressure Followed by Vacuum, can be used on opaque parts with an internal cavity. Method B, Penetrant-Pressure, can also be used on opaque parts with an internal cavity if the part is opened after dye penetration and before inspection. Parts that have an internal cavity may either contain gas (such as air, nitrogen, nitrogen-helium mixture, etc.) o...

  10. Visualization of Mesenchymal Stromal Cells in 2Dand 3D-Cultures by Scanning Electron Microscopy with Lanthanide Contrasting.

    Science.gov (United States)

    Novikov, I A; Vakhrushev, I V; Antonov, E N; Yarygin, K N; Subbot, A M

    2017-02-01

    Mesenchymal stromal cells from deciduous teeth in 2D- and 3D-cultures on culture plastic, silicate glass, porous polystyrene, and experimental polylactoglycolide matrices were visualized by scanning electron microscopy with lanthanide contrasting. Supravital staining of cell cultures with a lanthanide-based dye (neodymium chloride) preserved normal cell morphology and allowed assessment of the matrix properties of the carriers. The developed approach can be used for the development of biomaterials for tissue engineering.

  11. Spectral Fine Tuning of Cyanine Dyes: Electron Donor-Acceptor Substituted Analogues of Thiazole Orange†

    Science.gov (United States)

    Rastede, Elizabeth E.; Tanha, Matteus; Yaron, David; Watkins, Simon C.; Waggoner, Alan S.; Armitage, Bruce A.

    2015-01-01

    The introduction of electron donor and acceptor groups at strategic locations on a fluorogenic cyanine dye allows fine-tuning of the absorption and emission spectra while preserving the ability of the dye to bind to biomolecular hosts such as double-stranded DNA and a single-chain antibody fragment originally selected for binding to the parent unsubstituted dye, thiazole orange (TO). The observed spectral shifts are consistent with calculated HOMO-LUMO energy gaps and reflect electron density localization on the quinoline half of TO in the LUMO. A dye bearing donating methoxy and withdrawing trifluoromethyl groups on the benzothiazole and quinoline rings, respectively, shifts the absorption spectrum to sufficiently longer wavelengths to allow excitation at green wavelengths as opposed to the parent dye, which is optimally excited in the blue. PMID:26171668

  12. Focused ion beam scanning electron microscopy in biology.

    Science.gov (United States)

    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.

  13. Electronic and optical properties of dye-sensitized TiO₂ interfaces.

    Science.gov (United States)

    Pastore, Mariachiara; Selloni, Annabella; Fantacci, Simona; De Angelis, Filippo

    2014-01-01

    Dye-sensitized solar cells (DSCs) represent a promising approach to the direct conversion of sunlight to electrical energy at low cost and high efficiency. DSCs are based on a film of anatase TiO₂ nanoparticles covered by adsorbed molecular dyes and immersed in a liquid redox electrolyte. Upon photoexcitation of the chemisorbed dye, electrons are injected into the TiO₂ conduction band and can travel across the nanostructured film to reach the counter-electrode, while the oxidized dye is regenerated by the redox electrolyte. In this review we present a summary of recent computational studies of the electronic and optical properties of dye-sensitized TiO2 interfaces, with the aim of providing the basic understanding of the operation principles of DSCs and establishing the conceptual basis for their design and optimization.We start with a discussion of isolated dyes in solution, focusing on the dye's atomic structure, ground and excited state oxidation potentials, and optical absorption spectra. We examine both Ru(II)-polypyridyl complexes and organic "push-pull" dyes with a D-π-A structure, where the donor group (D) is an electron-rich unit, linked through a conjugated linker (π) to the electron-acceptor group (A). We show that a properly calibrated computational approach based on Density Functional Theory (DFT) combined with Time Dependent DFT (TD-DFT) can provide a good description of both the absorption spectra and ground and excited state oxidation potential values of the Ru(II) complexes. On the other hand, organic push-pull dyes are not well described by the standard DFT/TD-DFT approach. For these dyes, an excellent description of the electronic structure in gas phase can be obtained by the many body perturbation theory GW method, which has, however, a much higher computational cost.We next consider interacting dye/semiconductor systems. Key properties are the dye adsorption structure onto the semiconductor, the nature and localization of the dye

  14. Comparative study of depth and lateral distributions of electron excitation between scanning ion and scanning electron microscopes.

    Science.gov (United States)

    Ohya, Kaoru; Ishitani, Tohru

    2003-01-01

    In order to study the contrast difference between scanning ion microscopes (SIM) and scanning electron microscopes (SEM), the depth and lateral distributions of secondary electrons escaped from surfaces of 17 metals with atomic numbers, Z2, of 4-79 were calculated for bombardment with 30 keV Ga ions and for 10 keV electrons. For both projectiles, the excitation depth generally decreased with increasing Z2, while showing the same periodic change as the secondary-electron yield. However, an opposite trend in Z2 dependence between the Ga ion and electron bombardments was calculated with the lateral distribution of secondary electrons escaped from the surface. Except for low Z2 metals, the lateral distribution, which is much narrower for 30 keV Ga ions than for 10 keV electrons, indicates that the spatial resolution of the secondary-electron images is better for SIM than for SEM, if zero-sized probe beams are assumed. Furthermore, the present calculation reveals important effects of electron excitation by recoiled material atoms and reflected electrons on the lateral distribution, as well as the secondary-electron yield, for the Ga ion and electron bombardments, respectively.

  15. Electronic Scanning of UterineEndometrium in Postpartum Cow

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Two postpartum cows were used to study the ultrastructural changes of uterine endometrium by using scanning electron microscope. The results showed that the process of repair of uterine endometrium after calving was demonstrated by scanning electron microscope through a series of endometrium biopsy. Some part of the endometrium was damaged after calving and its adjacent endometrium cells became necrosis and exfoliated during the first 7 days post-partum;the cilium and microvillus of the epithelial cell in the undamaged area of the endometrium disappeared. By 26 days postpartum the damaged area reduced and the cilium and microvillus increased in their numbers. The damaged tissues were all repaired by day 60 postpartum.

  16. Ion charge neutralization effects in scanning electron microscopes.

    Science.gov (United States)

    Crawford, C K

    1980-01-01

    The use of low energy ion charge neutralization to stabilize surface potentials in scanning microscopes leads to the observation of new effects. Among the most important of these, are effects which result from the primary beam being scanned in a raster. A new theory which describes raster charge-up for highly insulating specimens is presented. It is shown that the required neutralizing ion current is a surprisingly strong function of the primary electron current, the raster parameters, specimen parameters, and magnification. Contrary to intuition, the required ion current is not linearly related to the primary electron current. Methods of adjusting parameters to achieve better ion charge neutralization are discussed.

  17. Compound Cellular Imaging of Laser Scanning Confocal Microscopy by Using Gold Nanoparticles and Dyes

    Directory of Open Access Journals (Sweden)

    Jiunn-Woei Liaw

    2008-04-01

    Full Text Available Combining the scattered light of gold nanoparticles (GNPs and the fluorescence of dye molecules, a compound cellular imaging of laser scanning confocal microscopy (LSCM is obtained. The human breast cancer cell line (MDA-MB-435S, BCRC 60429 is used for experiment. These cells are incubated with a glucose medium containing GNPs for 26 hours, and then are stained by Prodium Iodide (PI for their nuclei. By using a single laser to illuminate these cells and adjusting the ranges of two bandpass filters for the detection, the scattered light from the GNPs and the fluorescence of PI can be induced simultaneously, but be detected separately without crosstalk. Furthermore, a compound cellular image can be obtained by merging the two images of the expressions of GNP and PI together. From the TEM images of these cells, it is observed that GNPs are aggregated in the vesicles of the cytoplasm due to the cell’s endocytosis. The aggregation of GNPs makes the surface plasmon resonance band of GNPs broadened, so that strong scattered light from GNPs can be generated by the illumination of different-wavelength lasers (458, 488, 514, 561, and 633 nm.

  18. Third-order nonlinear optical properties of organic azo dyes by using strength of nonlinearity parameter and Z-scan technique

    Science.gov (United States)

    Motiei, H.; Jafari, A.; Naderali, R.

    2017-02-01

    In this paper, two chemically synthesized organic azo dyes, 2-(2,5-Dichloro-phenyazo)-5,5-dimethyl-cyclohexane-1,3-dione (azo dye (i)) and 5,5-Dimethyl-2-tolylazo-cyclohexane-1,3-dione (azo dye (ii)), have been studied from optical Kerr nonlinearity point of view. These materials were characterized by Ultraviolet-visible spectroscopy. Experiments were performed using a continous wave diode-pumped laser at 532 nm wavelength in three intensities of the laser beam. Nonlinear absorption (β), refractive index (n2) and third-order susceptibility (χ (3)) of dyes, were calculated. Nonlinear absorption coefficient of dyes have been calculated from two methods; 1) using theoretical fits and experimental data in the Z-scan technique, 2) using the strength of nonlinearity curves. The values of β obtained from both of the methods were approximately the same. The results demonstrated that azo dye (ii) displays better nonlinearity and has a lower two-photon absorption threshold than azo dye (i). Calculated parameter related to strength of nonlinearity for azo dye (ii) was higher than azo dye (i), It may be due to presence of methyl in azo dye (ii) instead of chlorine in azo dye (i). Furthermore, The measured values of third order susceptibility of azo dyes were from the order of 10-9 esu . These azo dyes can be suitable candidate for optical switching devices.

  19. Mechanism of electron transfer reaction for xanthene dye-sensitized formation of methyl viologen radical

    Energy Technology Data Exchange (ETDEWEB)

    Usui, Y.; Misawa, H.; Sakuragi, H.; Tokumaru, K.

    1987-05-01

    Sensitized reduction of methyl viologen, MV/sup 2 +/, occurs efficiently through electron transfer from triplet xanthene dyes to MV/sup 2 +/ followed by electron transfer to the resulting semioxidized dyes from a reductant like triethanolamine. Unreactive ion pair complexes between these dyes and MV/sup 2 +/ are formed (formation constant: 1.2 x 10/sup 3/ M/sup -1/ for Eosine Y and MV/sup 2 +/ in 50% aqueous ethanol solution). The quantum yield for the reduced methyl viologen radical depends on the concentrations of MV/sup 2 +/ and the amine and on the ionic strength of solution. The efficiency of the electron transfer from triplet dyes to MV/sup 2 +/ is increased by addition of alcohol, and solvent effects on the reaction mechanism are discussed. 38 references, 5 figures, 2 tables.

  20. Scanning tunneling spectroscopy on electron-boson interactions in superconductors

    CERN Document Server

    Schackert, Michael Peter

    2015-01-01

    This work describes the experimental study of electron-boson interactions in superconductors by means of inelastic electron tunneling spectroscopy performed with a scanning tunneling microscope (STM) at temperatures below 1 K. This new approach allows the direct measurement of the Eliashberg function of conventional superconductors as demonstrated on lead (Pb) and niobium (Nb). Preparative experiments on unconventional iron-pnictides are presented in the end.

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

    OpenAIRE

    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.

    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 cu...

  2. Surface sensitivity effects with local probe scanning Auger-scanning electron microscopy

    NARCIS (Netherlands)

    Van Agterveld, DTL; Palasantzas, G; De Hosson, JTM; Bentley, J; Allen, C; Dahmen, U; Petrov,

    2001-01-01

    Ultra-high-vacuum segregation studies on in-situ fractured Cu-Sb alloys were performed in terms of nanometer scale scanning Auger/Electron microscopy. S contamination leads to the formation Of Cu2S precipitates which, upon removal due to fracture, expose pits with morphology that depends on the prec

  3. Surface sensitivity effects with local probe scanning Auger-scanning electron microscopy

    NARCIS (Netherlands)

    Van Agterveld, DTL; Palasantzas, G; De Hosson, JTM; Bentley, J; Allen, C; Dahmen, U; Petrov,

    2001-01-01

    Ultra-high-vacuum segregation studies on in-situ fractured Cu-Sb alloys were performed in terms of nanometer scale scanning Auger/Electron microscopy. S contamination leads to the formation Of Cu2S precipitates which, upon removal due to fracture, expose pits with morphology that depends on the

  4. Impact of dyes on the nonlinear optical response of liquid crystals implementing the Z-scan technique

    Science.gov (United States)

    Rodríguez-Rosales, A. A.; Ortega-Martínez, R.; Morales-Saavedra, O. G.

    2011-01-01

    The study of the nonlinear refractive index response γ of several organic dyes and their impact on the nonlinear optical (NLO) properties of nematic liquid crystals (LC) was performed via Z-scan measurements. For his purpose, a low power CW He-Ne laser system (λ approx 633 nm) was implemented. Studies were carried out at the low absorption spectroscopic region of the implemented samples (dyes, liquid crystals and mixtures at different ratios of these materials). Samples were prepared at 1% weight of the used solvent (THF) and were sandwiched in glass cells with a gap thickness of ~100 μm. The implemented dyes have shown the largest optical nonlinearities and represent the main contributors to the cubic NLO-properties of the LC:Dye mixtures. In our particular studies, 5CB liquid crystal doped with DR1 azo-dye, resulted in the simultaneous positive and negative exhibition of nonlinear refractive indexes γ, depending on the polarization state of the excitation laser beam. Experimental conditions and results are described in detail.

  5. [Scanning electron microscope study of chemically disinfected endodontic files].

    Science.gov (United States)

    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.

  6. New Scanning Electron Microscope Used for Cryogenic Tensile Testing

    CERN Multimedia

    Maximilien Brice

    2013-01-01

    At CERN engineering department's installation for cryogenic tensile testing, the new scanning electron microscope (SEM) allows for detailed optical observations to be carried out. Using the SEM, surface coatings and tensile properties of materials can investigated in order to better understand how they behave under different conditions.

  7. Microstress contrast in scanning electron acoustic microscopy of ceramics

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  9. Scanning electron microscopy of the male genitalia of Sarcophagidae (Diptera

    Directory of Open Access Journals (Sweden)

    Hugo de Souza Lopes

    1990-03-01

    Full Text Available The male genitalia of nine species of Sarcophagidae (Diptera - Goniophyto honsuensis Rohdendorf, 1962, Tricharaea brevicornis (Wiedemann, 1830, Chaetoravinia derelicta (Walker, 1852, Austrohartigia spinigena (Rondani, 1864, Chrysagria duodecimpunctata Townsend, 1935, Boettcheria bisetosa Parker, 1914, Lipoptilocnema lanei Townsend, 1934, L. crispina (Lopes, 1938 and Euboettcheria alvarengai Lopes & Tibana, 1982 - were examined by scanning electron microscope (SEM and the main morphological features are descirbed.

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

    Science.gov (United States)

    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.

  11. Development of scanning electron and x-ray microscope

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Tomokazu, E-mail: tomokzau.matsumura@etd.hpk.co.jp; Hirano, Tomohiko, E-mail: tomohiko.hirano@etd.hpk.co.jp; Suyama, Motohiro, E-mail: suyama@etd.hpk.co.jp [Hamamatsu Photonics K.K., 314-5, Shimokanzo, Iwata City, Shizuoka-Pref. (Japan)

    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.

  12. Low voltage scanning electron microscopy of interplanetary dust particles

    Science.gov (United States)

    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.

  13. Low voltage scanning electron microscopy of interplanetary dust particles

    Science.gov (United States)

    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.

  14. Photopolymer material sensitized by xanthene dyes for holographic recording using forbidden singlet-triplet electronic transitions

    Science.gov (United States)

    Shelkovnikov, Vladimir; Vasiljev, Evgeny; Russkih, Vladimlen; Berezhnaya, Viktoria

    2016-07-01

    A new holographic photopolymer material is developed. The photopolymer material is sensitized by dyes of xanthene and thioxanthene series which contain iodine and bromine heavy atoms. Holographic recording was carried out during excitation of forbidden singlet-triplet electron transitions of dyes. Thioerythrosin triethylammonium was identified as the most effective sensitizer among a number of tested dyes. The spectral absorption area of the singlet-triplet electronic transition of the dye is conveyed in the red spectral range from 600 to 700 nm. The sensitivity of the photopolymer material to radiation with 633 nm wavelength is 180 mJ cm-2. Optimization of concentration of the main components of the photopolymer compositions was carried out in order to achieve maximum efficiency of holographic recording.

  15. Millimeter-wave electronically scanned reflectarray optimization and analysis

    Science.gov (United States)

    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.

  16. Closed-Loop Autofocus Scheme for Scanning Electron Microscope

    Directory of Open Access Journals (Sweden)

    Cui Le

    2015-01-01

    Full Text Available In this paper, we present a full scale autofocus approach for scanning electron microscope (SEM. The optimal focus (in-focus position of the microscope is achieved by maximizing the image sharpness using a vision-based closed-loop control scheme. An iterative optimization algorithm has been designed using the sharpness score derived from image gradient information. The proposed method has been implemented and validated using a tungsten gun SEM at various experimental conditions like varying raster scan speed, magnification at real-time. We demonstrate that the proposed autofocus technique is accurate, robust and fast.

  17. Miniaturized Environmental Scanning Electron Microscope for In Situ Planetary Studies

    Science.gov (United States)

    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.

  18. Correlations between Photovoltaic Characteristics, Adsorption Number, and Regeneration Kinetics in Dye-Sensitized Solar Cells Revealed by Scanning Photocurrent Microscopy.

    Science.gov (United States)

    Mitsui, Masaaki; Kawano, Yuya; Mori, Kyosuke; Wakabayashi, Naoto

    2015-06-30

    Newly developed simultaneous scanning photocurrent and luminescence microscopy was applied to ruthenium-based dye-sensitized solar cells (DSCs) comprising a cover glass photoanode with a 100 nm thick TiO2 layer. Using this, we have investigated the lateral variations of several parameters of these DSCs under short-circuit conditions. Simultaneous measurement of photocurrent and luminescence images for the same area of the DSC demonstrated submicrometric lateral resolution of our photocurrent microscopy, which is approximately 10 times better than the resolution of photocurrent microscopy used in past studies. The photovoltaic parameters, such as short-circuit current density, open-circuit voltage, and charge-collection efficiency, were thus evaluated for local (or submicrometric) regions of the DSCs. Furthermore, the photocurrent saturation behavior of the DSCs was examined as a function of the excitation rate and analyzed on the basis of a three-state kinetic model. This protocol allowed for quantification of the dye-adsorption number and dye-regeneration rate constant for any local area of the DSCs. Consequently, the correlations between the dye adsorption number, photovoltaic parameters, and regeneration rate constant, which are difficult to address through examination of the entire cell, were revealed by the "zoom-in" approach utilizing this high-resolution photocurrent microscopy.

  19. Third-Order Optical Nonlinearities of Squarylium Dyes with Benzothiazole Donor Groups Measured Using the Picosecond Z-Scan Technique

    Science.gov (United States)

    Li, Zhong-Yu; Xu, Song; Chen, Zi-Hui; Zhang, Fu-Shi; Kasatani, Kazuo

    2011-08-01

    Third-order optical nonlinearities of two squarylium dyes with benzothiazole donor groups (BSQ1 and BSQ2) in chloroform solution are measured by a picosecond Z-scan technique at 532 nm. It is found that the two compounds show the saturation absorption and nonlinear self-focus refraction effect. The molecular second hyperpolarizabilities are calculated to be 7.46 × 10-31 esu and 5.01 × 10-30 esu for BSQ1 and BSQ2, respectively. The large optical nonlinearities of squarylium dyes can be attributed to their rigid and intramolecular charge transfer structure. The difference in γ values is attributed to the chloro group of benzene rings of BSQ2 and the one-photon resonance effect. It is found that the third-order nonlinear susceptibilities of two squarylium dyes are mainly determined by the real parts of χ(3), and the large optical nonlinearities of studied squarylium dyes can be attributed to the nonlinear refraction.

  20. Third-Order Optical Nonlinearities of Squarylium Dyes with Benzothiazole Donor Groups Measured Using the Picosecond Z-Scan Technique

    Institute of Scientific and Technical Information of China (English)

    LI Zhong-Yu; XU Song; CHEN Zi-Hui; ZHANG Fu-Shi; KASATANI Kazuo

    2011-01-01

    @@ Third-order optical nonlinearities of two squarylium dyes with benzothiazole donor groups (BSQ1 and BSQ2)in chloroform solution are measured by a picosecond Z-scan technique at 532 nm.It is found that the two compounds show the saturation absorption and nonlinear self-focus refraction effect.The molecular second hyperpolarizabilities are calculated to be 7.46×10-31 esu and 5.01×10-30 esu for BSQ1 and BSQ2, respectively.The large optical nonlinearities of squarylium dyes can be attributed to their rigid and intramolecular charge transfer structure.The difference in γvalues is attributed to the chloro group of benzene rings of BSQ2 and the one-photon resonance effect.It is found that the third-order nonlinear susceptibilities of two squarylium dyes are mainly determined by the real parts of X(3), and the large optical nonlinearities of studied squarylium dyes can be attributed to the nonlinear refraction.

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

    Science.gov (United States)

    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.

  2. Nonlinear optical properties of natural laccaic acid dye studied using Z-scan technique

    CSIR Research Space (South Africa)

    Zongo, S

    2015-08-01

    Full Text Available We have investigated the nonlinear optical properties, including the optical limiting behaviour for five different concentrations of laccaic acid dye in solution and a thin film obtained through doping in poly (methyl methacrylate) (PMMA) polymer...

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

    Science.gov (United States)

    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.

  4. Scanning electron microscope studies of human metaphase chromosomes.

    Science.gov (United States)

    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.

  5. Scanning electron microscopy of erythropoietin-stimulated bone marrow

    Energy Technology Data Exchange (ETDEWEB)

    Leblond, P.F. (Hospital of St. Sacrement, Quebec); Chamberlain, J.K.; Weed, R.I.

    1975-01-01

    This work describes and illustrates the scanning electron microscopic modifications observed in the femoral bone marrow of normal mice 72 hours after a single injection of partly purified sheep erythropoietin and of mice afflicted with a chronic congenital hemolytic anemia analogous to the disease Hereditary Spherocytosis in man. In acordance with previous transmission electron microscopic studies, the observations are consistent with an effect of erythropoietin both on the frequency of cell migration across the normally intact marrow sinus endothelium and on the morphology of sinus adventitial cells. It is suggested that these ultrastructural modifications may be responsible for the greater patency of the marrow-blood barrier under erythropoietin stimulation.

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

    Science.gov (United States)

    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.

  7. SCANNING ELECTRON MICROSCOPY STUDY OF FILLED SILICONE RUBBER

    Institute of Scientific and Technical Information of China (English)

    LI Yufu; YANG Qiyun; LI Guangliang

    1988-01-01

    The fracture surfaces of a number of silicone vulcanizates were investigated by the use of scanning electron microscopy (SEM). It was found that the difference in the presence and absence of filler, the variation of its surface modification as well as the history of thermal aging of the vulcanizates, all of these factors made difference in surface morphology of the fractured surface. This was correlated with the strength of the vulcanizates. The reinforcing effect of filler and the process of fracture were discussed.

  8. Scanning electron microscopy physics of image formation and microanalysis

    CERN Document Server

    Reimer, Ludwig

    1985-01-01

    The aim of this book is to outline the physics of image formation, electron­ specimen interactions, imaging modes, the interpretation of micrographs and the use of quantitative modes "in scanning electron microscopy (SEM). lt forms a counterpart to Transmission Electron Microscopy (Vol. 36 of this Springer Series in Optical Sciences) . The book evolved from lectures delivered at the University of Münster and from a German text entitled Raster-Elektronenmikroskopie (Springer-Verlag), published in collaboration with my colleague Gerhard Pfefferkorn. In the introductory chapter, the principles of the SEM and of electron­ specimen interactions are described, the most important imaging modes and their associated contrast are summarized, and general aspects of eiemental analysis by x-ray and Auger electron emission are discussed. The electron gun and electron optics are discussed in Chap. 2 in order to show how an electron probe of small diameter can be formed, how the elec­ tron beam can be blanked at high fre...

  9. Scanning Electron Microscopy with Samples in an Electric Field

    Science.gov (United States)

    Frank, Ludĕk; Hovorka, Miloš; Mikmeková, Šárka; Mikmeková, Eliška; Müllerová, Ilona; Pokorná, Zuzana

    2012-01-01

    The high negative bias of a sample in a scanning electron microscope constitutes the “cathode lens” with a strong electric field just above the sample surface. This mode offers a convenient tool for controlling the landing energy of electrons down to units or even fractions of electronvolts with only slight readjustments of the column. Moreover, the field accelerates and collimates the signal electrons to earthed detectors above and below the sample, thereby assuring high collection efficiency and high amplification of the image signal. One important feature is the ability to acquire the complete emission of the backscattered electrons, including those emitted at high angles with respect to the surface normal. The cathode lens aberrations are proportional to the landing energy of electrons so the spot size becomes nearly constant throughout the full energy scale. At low energies and with their complete angular distribution acquired, the backscattered electron images offer enhanced information about crystalline and electronic structures thanks to contrast mechanisms that are otherwise unavailable. Examples from various areas of materials science are presented.

  10. Simulation and Characterization of a Miniaturized Scanning Electron Microscope

    Science.gov (United States)

    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.

  11. Synthesis and characterization of organic dyes with various electron-accepting substituents for p-type dye-sensitized solar cells.

    Science.gov (United States)

    Weidelener, Martin; Powar, Satvasheel; Kast, Hannelore; Yu, Ze; Boix, Pablo P; Li, Chen; Müllen, Klaus; Geiger, Thomas; Kuster, Simon; Nüesch, Frank; Bach, Udo; Mishra, Amaresh; Bäuerle, Peter

    2014-11-01

    Four new donor-π-acceptor dyes differing in their acceptor group have been synthesized and employed as model systems to study the influence of the acceptor groups on the photophysical properties and in NiO-based p-type dye-sensitized solar cells. UV/Vis absorption spectra showed a broad range of absorption coverage with maxima between 331 and 653 nm. Redox potentials as well as HOMO and LUMO energies of the dyes were determined from cyclic voltammetry measurements and evaluated concerning their potential use as sensitizers in p-type dye-sensitized solar cells (p-DSCs). Quantum-chemical density functional theory calculations gave further insight into the frontier orbital distributions, which are relevant for the electronic processes in p-DSCs. In p-DSCs using an iodide/triiodide-based electrolyte, the polycyclic 9,10-dicyano-acenaphtho[1,2-b]quinoxaline (DCANQ) acceptor-containing dye gave the highest power conversion efficiency of 0.08%, which is comparable to that obtained with the perylenemonoimide (PMI)-containing dye. Interestingly, devices containing the DCANQ-based dye achieve a higher V(OC) of 163 mV compared to 158 mV for the PMI-containing dye. The result was further confirmed by impedance spectroscopic analysis showing higher recombination resistance and thus a lower recombination rate for devices containing the DCANQ dye than for PMI dye-based devices. However, the use of the strong electron-accepting tricyanofurane (TCF) group played a negative role in the device performance, yielding an efficiency of only 0.01% due to a low-lying LUMO energy level, thus resulting in an insufficient driving force for efficient dye regeneration. The results demonstrate that a careful molecular design with a proper choice of the acceptor unit is essential for development of sensitizers for p-DSCs.

  12. Probing Nanoscale Electronic and Magnetic Interaction with Scanning Tunneling Spectroscopy

    DEFF Research Database (Denmark)

    Bork, Jakob

    This thesis is concerned with fundamental research into electronic and magnetic interaction on the nanoscale. From small metallic and magnetic islands and layers to single atoms. The research revolves around magnetic interaction probed through the spectroscopic capabilities of the scanning....... This is related to research in correlated electron materials such as studies of phase transitions in heavy fermion compounds and magnetic interaction in spintronic research. The capping of cobalt islands on Cu(111) with silver is investigated with STM and photoemission spectroscopy. It is shown that at low...... coverage the silver preferably nucleates on top of the bilayer high cobalt islands compared to directly on the Cu(111) substrate. Furthermore, the silver forms a combination of a reconstruction and a Moire pattern which is investigated with low-energy electron diraction and spectroscopic STM mapping at 6...

  13. Scanning transmission electron microscopy imaging dynamics at low accelerating voltages

    Energy Technology Data Exchange (ETDEWEB)

    Lugg, N.R. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Findlay, S.D. [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); Shibata, N. [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); PRESTO, Japan Science and Technology Agency, Saitama 332-0012 (Japan); Mizoguchi, T. [Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505 (Japan); D' Alfonso, A.J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Allen, L.J., E-mail: lja@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Ikuhara, Y. [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); Nanostructures Research Laboratory, Japan Fine Ceramic Center, Nagoya 456-8587 (Japan); WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2011-07-15

    Motivated by the desire to minimize specimen damage in beam sensitive specimens, there has been a recent push toward using relatively low accelerating voltages (<100kV) in scanning transmission electron microscopy. To complement experimental efforts on this front, this paper seeks to explore the variations with accelerating voltage of the imaging dynamics, both of the channelling of the fast electron and of the inelastic interactions. High-angle annular-dark field, electron energy loss spectroscopic imaging and annular bright field imaging are all considered. -- Highlights: {yields} Both elastic and inelastic scattering in STEM are acceleration voltage dependent. {yields} HAADF, EELS and ABF imaging are assessed with a view to optimum imaging. {yields} Lower accelerating voltages improve STEM EELS contrast in very thin crystals. {yields} Higher accelerating voltages give better STEM EELS contrast in thicker crystals. {yields} At fixed resolution, higher accelerating voltage aids ABF imaging of light elements.

  14. Cryo scanning electron microscopy of Plasmodium falciparum-infected erythrocytes.

    Science.gov (United States)

    Hempel, Casper

    2017-07-01

    Plasmodium falciparum invades erythrocytes as an essential part of their life cycle. While living inside erythrocytes, the parasite remodels the cell's intracellular organization as well as its outer surface. Late trophozoite-stage parasites and schizonts introduce numerous small protrusions on the erythrocyte surface, called knobs. Current methods for studying these knobs include atomic force microscopy and electron microscopy. Standard electron microscopy methods rely on chemical fixation and dehydration modifying cell size. Here, a novel method is presented using rapid freezing and scanning electron microscopy under cryogenic conditions allowing for high resolution and magnification of erythrocytes. This novel technique can be used for precise estimates of knob density and for studies on cytoadhesion. © 2017 APMIS. Published by John Wiley & Sons Ltd.

  15. Electron Transfer in D-B-A Model Systems and Dye-Sensitized Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Wiberg, Joanna

    2010-01-15

    This Thesis presents a thorough study of the electron transfer (ET) processes, both inter-molecular - between dyes for dye-sensitized solar cells (DSSCs), and intra-molecular - in porphyrin based electron donor-bridge-electron acceptor model systems. The focus has been on charge separation and subsequent re-combination in the femtosecond-nanosecond range in both systems. Studying these processes on nanocrystalline mesoporous films in rather heterogeneous systems for solar cell application is quite a challenge. Therefore, the knowledge gained by studying the same type of processes in designed model systems is in-valuable. To this end, ET has been verified and studied in a series of donor-bridge-acceptor (D-B-A) model systems using femtosecond transient absorption. The D-B-A series show photo-induced ET with exponential distance dependence via superexchange interactions. The attenuation factor of the ET rate, beta, was shown to be direction specific, which is in accordance with the McConnell model. A parallel study of the influence of the barrier height showed that the decrease in electronic coupling for the charge recombination (CR) reaction could be correlated to the impact of charge location. The importance of charge location was also used to explain the large differences in energy conversion efficiency found for two solar cell dyes with differently conjugated anchoring groups adsorbed on TiO{sub 2}. The disparity in energy conversion efficiency for these two dyes was ascribed to the effect of differences in electron density on the binding oxygens, rather than efficiency variations in the injection process. An exponential distance dependence for CR was found also for dyes adsorbed on TiO{sub 2}, with attenuation factors similar to those found for the D-B-A system. In addition, the hole transfer to and from NiO films was studied for two p-type dyes that had shown great differences in current generation. The CR was found to be slower for the dye with the strongest

  16. Fabrication and characterization of a composite ZnO semiconductor as electron transporting layer in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Karst, N.; Rey, G. [Laboratoire des Materiaux et du Genie Physique (LMGP) Grenoble INP, 38016 Grenoble (France); Doisneau, B. [Laboratoire de Science et Ingenierie des Materiaux et Procedes (SIMAP), 38402 Saint Martin d' Heres (France); Roussel, H.; Deshayes, R. [Laboratoire des Materiaux et du Genie Physique (LMGP) Grenoble INP, 38016 Grenoble (France); Consonni, V. [Laboratoire des Materiaux et du Genie Physique (LMGP) Grenoble INP, 38016 Grenoble (France); Laboratoire des Technologies de la Microelectronique (LTM), 38054 Grenoble (France); Ternon, C. [Laboratoire des Technologies de la Microelectronique (LTM), 38054 Grenoble (France); Bellet, D., E-mail: daniel.bellet@grenoble-inp.fr [Laboratoire des Materiaux et du Genie Physique (LMGP) Grenoble INP, 38016 Grenoble (France)

    2011-05-15

    ZnO nanocomposites involving nanowires and nanoparticles with a thickness of 4 {mu}m were grown by chemical bath deposition and used as electron transporting layer in dye-sensitized solar cells (DSSCs). The growth of ZnO nanowires was initially achieved in a zinc nitrate and hexamethylenetetramine aqueous solution on a fluorine-doped tin oxide thin film seeded with ZnO nanoparticles. Subsequently, layered hydroxide zinc acetate (LHZA) nanoparticles were deposited on the nanowires by dip coating in a zinc acetate methanolic solution. A relatively conformal deposit of nanoparticles all along the nanowires was revealed by scanning and transmission electron microscopy. It is shown by X-ray diffraction measurements that a subsequent annealing convert the LHZA nanoparticles into ZnO nanoparticles. The resulting DSSCs present a short circuit current density almost three times higher when the ZnO nanowire interstices were filled with ZnO nanoparticles, which is due to a higher dye loading for a constant device thickness. This is correlated with a very high specific surface area in ZnO nanocomposites, which is 250 times larger than the geometrical surface area. Although a decrease in both the open circuit voltage and the fill factor was shown by electrochemical impedance spectroscopy owing to an increase in electron radiative and nonradiative recombinations, the efficiency of ZnO nanocomposite-based-DSSCs was on average 1.75%, which is 70% higher than for single ZnO nanowire-based-DSSCs.

  17. Energy Filtering and Coaxial Detection of the Backscattered Electrons in Scanning Electron Microscope

    Institute of Scientific and Technical Information of China (English)

    JIANG Chang-Zhong; P. Morin; N. Rosenberg

    2000-01-01

    A new detection system in scanning electron microscope, which filters in energy and detects the backscattered electrons close to the microscope axis, is described. This technique ameliorates the dependence of the back. scat tering coefficient on atomic number, and suppresses effectively the relief contrast at the same time. Therefore this new method is very suitable to the composition analysis.

  18. Photoemission electron microscopy and scanning electron microscopy of Magnetospirillum magnetotacticum's magnetosome chains.

    Science.gov (United States)

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

    2014-10-01

    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.

  19. Study of nonlinear refraction of organic dye by Z-scan technique using He-Ne laser

    Science.gov (United States)

    Medhekar, S.; Kumar, R.; Mukherjee, S.; Choubey, R. K.

    2013-02-01

    Laser induced third-order nonlinear optical responses of Brilliant Green solution has been investigated by utilizing single beam Z-scan technique with a continuous-wave He-Ne laser radiation at 632.8 nm. It was observed that the material exhibits self-defocusing type optical nonlinearity. The measurements of nonlinear refraction were carried out at different dye concentrations and found that the increase in solution concentration leads to the linear increase of the nonlinear refractive index. The experimental results confirm great potential of the Brilliant Green for the application in nonlinear optical devices.

  20. Study of nonlinear refraction of organic dye by Z-scan technique using He-Ne laser

    Energy Technology Data Exchange (ETDEWEB)

    Medhekar, S.; Kumar, R.; Mukherjee, S.; Choubey, R. K. [Dept. of Applied Physics, Birla Institute of Technology, Mesra, Ranchi - 835215, Jharkhand (India)

    2013-02-05

    Laser induced third-order nonlinear optical responses of Brilliant Green solution has been investigated by utilizing single beam Z-scan technique with a continuous-wave He-Ne laser radiation at 632.8 nm. It was observed that the material exhibits self-defocusing type optical nonlinearity. The measurements of nonlinear refraction were carried out at different dye concentrations and found that the increase in solution concentration leads to the linear increase of the nonlinear refractive index. The experimental results confirm great potential of the Brilliant Green for the application in nonlinear optical devices.

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

    Energy Technology Data Exchange (ETDEWEB)

    Morandi, V., E-mail: morandi@bo.imm.cnr.it; Maccagnani, P.; Masini, L.; Migliori, A.; Ortolani, L.; Pezza, A. [CNR-IMM Sezione di Bologna, via Gobetti 101, 40129 Bologna (Italy); Del Marro, M.; Pallocca, G.; Vinciguerra, P. [ASSING S.P.A., via E. Amaldi 14, 00016 Monterotondo (Rome) (Italy); Rossi, M.; Ferroni, M. [Dip.to di Scienze di Base e Applicate per l’Ingegneria and Centro di Ricerca per le Nanotecnologie Applicate all’Ingegneria (CNIS), Università degli Studi di Roma “Sapienza”, Via A. Scarpa, 00161 Rome (Italy); Sberveglieri, G. [SENSOR Lab, Dip.to di Ingegneria dell’Informazione, Università degli Studi di Brescia and CNR-INO, Via Valotti 9, 25123 Brescia (Italy); Vittori-Antisari, M. [Unità Tecnica Tecnologie dei Materiali, ENEA Centro Ricerche Casaccia, Via Anguillarese 301, 00123 S. Maria di Galeria (Rome) (Italy)

    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.

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

    Science.gov (United States)

    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

  3. Universal electron injection dynamics at nanointerfaces in dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lei; Wang, Hai-Yu; Fang, Hong-Hua; Gao, Bing-Rong; Chen, Qi-Dai [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun (China); Wang, Hai; Yang, Zhi-Yong; Sun, Hong-Bo [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun (China); College of Physics, Jilin University, Changchun (China); Han, Wei [College of Physics, Jilin University, Changchun (China)

    2012-07-10

    Initial nanointerfacial electron transfer dynamics are studied in dye-sensitized solar cells (DSSCs) in which the free energy and kinetics vary over a broad range. Surprisingly, it is found that the decay profiles, reflecting the electron transfer behavior, show a universal shape despite the different kinds of dye and semiconductor nanocrystalline films, even across different device types. This renews intuitive knowledge about the electron injection process in DSSCs. In order to quantitatively comprehend the universal behavior, a static inhomogeneous electronic coupling model with a Gaussian distribution of local injection energetics is proposed in which only the electron injection rate is a variant. It is confirmed that this model can be extended to CdSe quantum dot-sensitized films. These unambiguous results indicate exactly the same physical distribution in electron injection process of different sensitization films, providing limited simple and important parameters describing the electron injection process including electronic coupling constant and reorganization energy. The results provide insight into photoconversion physics and the design of optimal metal-free organic dye-sensitized photovoltaic devices by molecular engineering. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Scanning Electron Microscopy of Lagochilascaris minor Leiper, 1909 (Nematoda: Ascarididae

    Directory of Open Access Journals (Sweden)

    Lanfredi Reinalda Marisa

    1998-01-01

    Full Text Available Lagochilascaris minor Leiper, 1909 is a parasitic nematode with its biological cycle still unknown, even though it was found in humans, domestic and silvatic animals. Adult worms, collected by surgical drainage from a human patient from the State of Pará, Brazil, were micrographed using a scanning electron microscope. Morphological aspects of males and females such as cephalic structures, caudal papillae and cuticular patterns were analyzed and compared with the previous descriptions adding new data for the identification of this species.

  5. Measurement of dihedral angles by scanning electron microscopy.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  7. Simulation of scanning transmission electron microscope images on desktop computers

    Energy Technology Data Exchange (ETDEWEB)

    Dwyer, C., E-mail: christian.dwyer@mcem.monash.edu.au [Monash Centre for Electron Microscopy, Department of Materials Engineering, Monash University, Victoria 3800 (Australia)

    2010-02-15

    Two independent strategies are presented for reducing the computation time of multislice simulations of scanning transmission electron microscope (STEM) images: (1) optimal probe sampling, and (2) the use of desktop graphics processing units. The first strategy is applicable to STEM images generated by elastic and/or inelastic scattering, and requires minimal effort for its implementation. Used together, these two strategies can reduce typical computation times from days to hours, allowing practical simulation of STEM images of general atomic structures on a desktop computer.

  8. Microcircuit failure analysis using the SEM. [Scanning Electron Microscopes

    Science.gov (United States)

    Nicolas, D. P.

    1974-01-01

    The scanning electron microscope adds a new dimension to the knowledge that can be obtained from a failed microcircuit. When used with conventional techniques, SEM assists and clarifies the analysis, but it does not replace light microscopy. The most advantageous features for microcircuit analysis are long working distances and great depth of field. Manufacturer related failure modes of microcircuits are metallization defects, poor bonding, surface and particle contamination, and design and fabrication faults. User related failure modes are caused by abuse, such as overstress. The Physics of Failure Procedure followed by the Astrionics Laboratory in failure analysis is described, which is designed to obtain maximum information available from each step.

  9. [A scanning electron microscope observation of Dictyocaulus filaria.].

    Science.gov (United States)

    Yildiz, Kader; Cavuşoğlu, Kültiğin

    2005-01-01

    In this study, D. filaria causing parasitic bronchopneumonia in sheep was observed using a scanning electron microscope. This parasite belongs to the Trichostrongyloidea super family. The oral opening of D. filaria was observed to be small and circular in shape. Lips were not evident. Any difference between anterior ends of male and female parasites was not observed in present study. In the female parasite, the anus was seen as a fissure in shape. The post anal papilla was seen near the posterior end of the female. Spicula and cloacae of male parasites were observed.

  10. Measurement of dihedral angles by scanning electron microscopy.

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sim, K. S., E-mail: kssim@mmu.edu.my; Nia, M. E.; Tan, T. L.; Tso, C. P.; Ee, C. S. [Faculty of Engineering and Technology, Multimedia University, 75450 Melaka (Malaysia)

    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.

  12. Enhanced Performance of Dye-Sensitized Solar Cells with Nanostructure Graphene Electron Transfer Layer

    Directory of Open Access Journals (Sweden)

    Chih-Hung Hsu

    2014-01-01

    Full Text Available The utilization of nanostructure graphene thin films as electron transfer layer in dye-sensitized solar cells (DSSCs was demonstrated. The effect of a nanostructure graphene thin film in DSSC structure was examined. The nanostructure graphene thin films provides a great electron transfer channel for the photogenerated electrons from TiO2 to indium tin oxide (ITO glass. Obvious improvements in short-circuit current density of the DSSCs were observed by using the graphene electron transport layer modified photoelectrode. The graphene electron transport layer reduces effectively the back reaction in the interface between the ITO transparent conductive film and the electrolyte in the DSSC.

  13. Kinetics study of ultrafast electron transfer from sensitized dyes to silver halide microcrystals

    Institute of Scientific and Technical Information of China (English)

    Yang Shao-Peng; Fan Guo-Zhi; Fan Shan-Shan; Cao Ning; Li Xiao-Wei; Jiang Xiao-Li; Fu Guang-Sheng

    2006-01-01

    Spectral sensitization micromechanism of cyanine dyes J-aggregate adsorbed on the tabular and cubic AgBr microcrystals with different dye concentrations is studied by using picosecond time-resolved fluorescence spectroscopy,and the dependences of electron transfer and spectral efficiency sensitization on different conditions are analysed in detail. With the steady spectroscopy, the wavelengths of absorption and fluorescence of J-aggregate adsorbed on AgBr microcrystals are found to shift to red relative to dye monomer. The spectrum of fluorescence has a red shift relative to the absorption peak. With the time-resolved fluorescence spectroscopy, the fluorescence decay curves of cyanine dyes J-aggregate adsorbed on the tabular and cubic AgBr grains are found to be fitted well by a double-exponential decay function. The fitting curves consist of a fast and a slow component. Because of the large amplitude of the fast component, this fast decay should be attributable mainly to the electron transfer from J-aggregate of dye to a conduction band of AgBr.

  14. Chlorophyll J-aggregates: from bioinspired dye stacks to nanotubes, liquid crystals, and biosupramolecular electronics.

    Science.gov (United States)

    Sengupta, Sanchita; Würthner, Frank

    2013-11-19

    of the 17(2)-position with esterified hydrophilic or hydrophobic chains, dendron-wedge substituents, and chromophores having complementary optical properties such as naphthalene bisimides (NBIs) is used to modulate the self-assembly of ZnChl dyes. The resulting assemblies exhibit enhanced charge transport and energy transfer abilities. We have used UV/vis, circular dichroism (CD), fluorescence spectroscopy, and dynamic light scattering (DLS) for the characterization of these assemblies in solution. In addition, we have studied assembly morphologies by atomic force microscopy (AFM), scanning tunneling microscopy (STM), transmission electron microscopy (TEM), and cryogenic-TEM. Crystallographic techniques such as powder X-ray and solid-state NMR have been used to explain the precise long- and short-range packing of dyes in these assemblies. Finally, functional properties such as charge and energy transport have been explored by pulse radiolysis time-resolved microwave conductivity (PR-TRMC), conductive AFM, and time-resolved fluorescence spectroscopy. The design principles discussed in this Account are important steps toward the utilization of these materials in biosupramolecular electronics and photonics in the future.

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

    Science.gov (United States)

    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.

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

    CERN Document Server

    Levin, Barnaby D A; 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; Abruna, 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{\\deg} 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 p...

  17. Theory and application of scanning electron acoustic microscopy

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  20. Morphological classification of bioaerosols from composting using scanning electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tamer Vestlund, A. [Institute for Energy and Resource Technology, Environmental Science and Technology Department, School of Applied Sciences, Cranfield University, Building 40, Bedfordshire MK43 0AL (United Kingdom); FIRA International Ltd., Maxwell Road, Stevenage, Herts SG1 2EW (United Kingdom); Al-Ashaab, R.; Tyrrel, S.F.; Longhurst, P.J.; Pollard, S.J.T. [Institute for Energy and Resource Technology, Environmental Science and Technology Department, School of Applied Sciences, Cranfield University, Building 40, Bedfordshire MK43 0AL (United Kingdom); Drew, G.H., E-mail: g.h.drew@cranfield.ac.uk [Institute for Energy and Resource Technology, Environmental Science and Technology Department, School of Applied Sciences, Cranfield University, Building 40, Bedfordshire MK43 0AL (United Kingdom)

    2014-07-15

    Highlights: • Bioaerosols were captured using the filter method. • Bioaerosols were analysed using scanning electron microscope. • Bioaerosols were classified on the basis of morphology. • Single small cells were found more frequently than aggregates and larger cells. • Smaller cells may disperse further than heavier aggregate structures. - Abstract: This research classifies the physical morphology (form and structure) of bioaerosols emitted from open windrow composting. Aggregation state, shape and size of the particles captured are reported alongside the implications for bioaerosol dispersal after release. Bioaerosol sampling took place at a composting facility using personal air filter samplers. Samples were analysed using scanning electron microscopy. Particles were released mainly as small (<1 μm) single, spherical cells, followed by larger (>1 μm) single cells, with aggregates occurring in smaller proportions. Most aggregates consisted of clusters of 2–3 particles as opposed to chains, and were <10 μm in size. No cells were attached to soil debris or wood particles. These small single cells or small aggregates are more likely to disperse further downwind from source, and cell viability may be reduced due to increased exposure to environmental factors.

  1. Solar cell evaluation using electron beam induced current with the large chamber scanning electron microscope

    Science.gov (United States)

    Wink, Tara; Kintzel, Edward; Marienhoff, Peter; Klein, Martin

    2012-02-01

    An initial study using electron beam induced current (EBIC) to evaluate solar cells has been carried out with the large chamber scanning electron microscope (LC-SEM) at the Western Kentucky University Nondestructive Analysis Center. EBIC is a scanning electron microscope technique used for the characterization of semiconductors. To facilitate our studies, we developed a Solar Amplification System (SASY) for analyzing current distribution and defects within a solar cell module. Preliminary qualitative results will be shown for a solar cell module that demonstrates the viability of the technique using the LC-SEM. Quantitative EBIC experiments will be carried out to analyze defects and minority carrier properties. Additionally, a well-focused spot of light from an LED mounted at the side of the SEM column will scan the same area of the solar cell using the LC-SEM positioning system. SASY will then output the solar efficiency to be compared with the minority carrier properties found using EBIC.

  2. Direct current scanning field emission microscope integrated with existing scanning electron microscope

    Science.gov (United States)

    Wang, Tong; Reece, Charles E.; Sundelin, Ronald M.

    2002-09-01

    Electron field emission (FE) from broad-area metal surfaces is known to occur at much lower electric field than predicted by Fowler-Nordheim law. Although micron or submicron particles are often observed at such enhanced field emission (EFE) sites, the strength and number of emitting sites and the causes of EFE strongly depend on surface preparation and handling, and the physical mechanism of EFE remains unknown. To systematically investigate the sources of this emission, a dc scanning field emission microscope (SFEM) has been built as an extension to an existing commercial scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer for emitter characterization. In the SFEM chamber of ultrahigh vacuum (approx10-9 Torr), a sample is moved laterally in a raster pattern (2.5 mum step resolution) under a high voltage anode microtip for field emission detection and localization. The sample is then transferred under vacuum by a hermetic retractable linear transporter to the SEM chamber for individual emitter site characterization. Artificial marks on the sample surface serve as references to convert x, y coordinates of emitters in the SFEM chamber to corresponding positions in the SEM chamber with a common accuracy of plus-or-minus100-200 mum in x and y. Samples designed to self-align in sample holders are used in each chamber, allowing them to retain position registration after non-in situ processing to track interesting features. No components are installed inside the SEM except the sample holder, which does not affect the routine operation of the SEM. The apparatus is a system of low cost and maintenance and significant operational flexibility. Field emission sources from planar niobium--the material used in high-field rf superconducting cavities for particle accelerator--have been studied after different surface preparations, and significantly reduced field emitter density has been achieved by refining the preparation process based on scan

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Peng; Behan, Gavin; Kirkland, Angus I. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Nellist, Peter D., E-mail: peter.nellist@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Cosgriff, Eireann C.; D' Alfonso, Adrian J.; Morgan, Andrew J.; Allen, Leslie J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Hashimoto, Ayako [Advanced Nano-characterization Center, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba 305-0003 (Japan); Takeguchi, Masaki [Advanced Nano-characterization Center, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba 305-0003 (Japan); High Voltage Electron Microscopy Station, NIMS, 3-13 Sakura, Tsukuba 305-0003 (Japan); Mitsuishi, Kazutaka [Advanced Nano-characterization Center, National Institute for Materials Science (NIMS), 3-13 Sakura, Tsukuba 305-0003 (Japan); Quantum Dot Research Center, NIMS, 3-13 Sakura, Tsukuba 305-0003 (Japan); Shimojo, Masayuki [High Voltage Electron Microscopy Station, NIMS, 3-13 Sakura, Tsukuba 305-0003 (Japan); Advanced Science Research Laboratory, Saitama Institute of Technology, 1690 Fusaiji, Fukaya 369-0293 (Japan)

    2011-06-15

    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. -- Research Highlights: {yields} The confocal probe image in a scanning confocal electron microscopy image reveals information about the thickness and height of the crystalline layer. {yields} The form of the contrast in a three-dimensional bright-field scanning confocal electron microscopy image can be explained in terms of the confocal probe image. {yields} Despite the complicated form of the contrast in bright-field scanning confocal electron microscopy, we see that depth information is transferred on a 10 nm scale.

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

    Science.gov (United States)

    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.

  6. Advances in imaging and electron physics the scanning transmission electron microscope

    CERN Document Server

    Hawkes, Peter W

    2009-01-01

    Advances in Imaging and Electron Physics merges two long-running serials--Advances in Electronics and Electron Physics and Advances in Optical and Electron Microscopy. This series features extended articles on the physics of electron devices (especially semiconductor devices), particle optics at high and low energies, microlithography, image science and digital image processing, electromagnetic wave propagation, electron microscopy, and the computing methods used in all these domains.  This particular volume presents several timely articles on the scanning transmission electron microscope. Updated with contributions from leading international scholars and industry experts Discusses hot topic areas and presents current and future research trends Provides an invaluable reference and guide for physicists, engineers and mathematicians.

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

    Science.gov (United States)

    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

  8. Destructive effects induced by the electron beam in scanning electron microscopy

    Science.gov (United States)

    Popescu, M. C.; Bita, B. I.; Banu, M. A.; Tomescu, R. M.

    2016-12-01

    The Scanning Electron Microscopy has been validated by its impressive imaging and reliable measuring as an essential characterization tool for a variety of applications and research fields. This paper is a comprehensive study dedicated to the undesirable influence of the accelerated electron beam associated with the dielectric materials, sensitive structures or inappropriate sample manipulation. Depending on the scanning conditions, the electron beam may deteriorate the investigated sample due to the extended focusing or excessive high voltage and probe current applied on vulnerable configurations. Our aim is to elaborate an instructive material for improved SEM visualization capabilities by overcoming the specific limitations of the technique. Particular examination and measuring methods are depicted along with essential preparation and manipulation procedures in order to protect the integrity of the sample. Various examples are mentioned and practical solutions are described in respect to the general use of the electron microscope.

  9. Three-Dimensional scanning transmission electron microscopy of biological specimens

    KAUST Repository

    De Jonge, Niels

    2010-01-18

    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. © 2010 Microscopy Society of America.

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

    Science.gov (United States)

    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.

  11. Bacterial decolorization of textile dyes is an extracellular process requiring a multicomponent electron transfer pathway.

    Science.gov (United States)

    Brigé, Ann; Motte, Bart; Borloo, Jimmy; Buysschaert, Géraldine; Devreese, Bart; Van Beeumen, Jozef J

    2008-01-01

    Many studies have reported microorganisms as efficient biocatalysts for colour removal of dye-containing industrial wastewaters. We present the first comprehensive study to identify all molecular components involved in decolorization by bacterial cells. Mutants from the model organism Shewanella oneidensis MR-1, generated by random transposon and targeted insertional mutagenesis, were screened for defects in decolorization of an oxazine and diazo dye. We demonstrate that decolorization is an extracellular reduction process requiring a multicomponent electron transfer pathway that consists of cytoplasmic membrane, periplasmic and outer membrane components. The presence of melanin, a redox-active molecule excreted by S. oneidensis, was shown to enhance the dye reduction rates. Menaquinones and the cytochrome CymA are the crucial cytoplasmic membrane components of the pathway, which then branches off via a network of periplasmic cytochromes to three outer membrane cytochromes. The key proteins of this network are MtrA and OmcB in the periplasm and outer membrane respectively. A model of the complete dye reduction pathway is proposed in which the dye molecules are reduced by the outer membrane cytochromes either directly or indirectly via melanin.

  12. Conditioning of mealybug (Hemiptera: Pseudococcidae by Scanning Electron Microscopy.

    Directory of Open Access Journals (Sweden)

    Melissa Palma-Jiménez

    2015-06-01

    Full Text Available The aim of this work was to determine the methodology for an adequate conditioning for the cleaning of mealybugs specimens and its correct observation. This work was done in the laboratory of the Research Center in Microscopic Structures (CIEMIC of the University of Costa Rica, in 2012. Four types of methodologies were implemented, which evidenced a gradual improvement of the observation of the ultrastructures through the Scanning Electron Microscopy. Every process was described in detail. The best results were showed with 10% xylene (in some cases it was feasible using 95-100% ethanol. It allowed to remove the wax from the body of the insect, avoiding its collapse, and observing the specific ultrastructures of the individual. This approach will reduce the time and cost of future taxonomic research of mealybugs.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  15. Scanning electron microscopy of congenital corneal leukomas (Peters' anomaly).

    Science.gov (United States)

    Polack, F M; Graue, E L

    1979-08-01

    Specimens of three corneas in two patients with Peter's anomaly were obtained at the time of penetrating keratoplasty and studied by scanning and transmission electron microscopy. In one patient, the anomaly was monocular, and the endothelial surface showed a central defect in Descemet's layer with isolated rounded defects in the midperiphery. Fine collagenous material covered the posterior surface. The other two specimens were obtained from a patient with rubella syndrome without cataracts. The cornea showed malformation of Descemet's membrane with fibroblastic overgrowth on the endothelial layer. Epithelial-like cells and leukocytes were also found. The congenital central leukoma we believe was caused by adhesion of the pupillary membrane in our first patient, and possibly was inflammatory in our second patient.

  16. Trichomes of Cannabis sativa as viewed with scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Ledbetter, M.C.; Krikorian, A.D.

    1975-06-01

    Direct examination of fresh, unfixed and uncoated specimens from vegetative and floral parts of Cannabis sativa with the scanning electron microscope enables one to obtain a faithful representation of their surface morphology. The presence of two major types of trichomes has been confirmed: a glandular type comprising or terminating in a globoid structure, and a conically-shaped nonglandular type. Moreover, three or possibly four distinct glandular types can be distinguished: sessile globoid, small-stalked and large-stalked globoid, and a peltate type. The nonglandular trichomes can be distinguished by the nature of their surfaces: those with a warty surface, and those which are relatively smooth. The range of size and distribution, and the special features of all these types of trichomes are also provided.

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

    Science.gov (United States)

    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.

  18. Quantitative Electron Probe Microanalysis Using a Scanning Electron Microscope and an X-Ray Energy Spectrometer.

    Science.gov (United States)

    1980-04-01

    show the results obtained for the analyses of three different alloys. Table 1 shows the results obtained for NBS SRM 162a monel alloy. Table 2 shows the...pro- vided by Mr. D.O. Morehouse in preparing samples and operating the scanning electron microscope. TABLE 1 MONEL TYPE ALLOY - NBS SRM 162a NBS

  19. Monte Carlo simulation of secondary electron images for real sample structures in scanning electron microscopy.

    Science.gov (United States)

    Zhang, P; Wang, H Y; Li, Y G; Mao, S F; Ding, Z J

    2012-01-01

    Monte Carlo simulation methods for the study of electron beam interaction with solids have been mostly concerned with specimens of simple geometry. In this article, we propose a simulation algorithm for treating arbitrary complex structures in a real sample. The method is based on a finite element triangular mesh modeling of sample geometry and a space subdivision for accelerating simulation. Simulation of secondary electron image in scanning electron microscopy has been performed for gold particles on a carbon substrate. Comparison of the simulation result with an experiment image confirms that this method is effective to model complex morphology of a real sample.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. An electro-optical and electron injection study of benzothiazole-based squaraine dyes as efficient dye-sensitized solar cell materials: a first principles study.

    Science.gov (United States)

    Al-Fahdan, Najat Saeed; Asiri, Abdullah M; Irfan, Ahmad; Basaif, Salem A; El-Shishtawy, Reda M

    2014-12-01

    Squaraine dyes have attracted significant attention in many areas of daily life from biomedical imaging to semiconducting materials. Moreover, these dyes are used as photoactive materials in the field of solar cells. In the present study, we investigated the structural, electronic, photophysical, and charge transport properties of six benzothiazole-based squaraine dyes (Cis-SQ1-Cis-SQ3 and Trans-SQ1-Trans-SQ3). The effect of electron donating (-OCH3) and electron withdrawing (-COOH) groups was investigated intensively. Ground state geometry and frequency calculations were performed by applying density functional theory (DFT) at B3LYP/6-31G** level of theory. Absorption spectra were computed in chloroform at the time-dependent DFT/B3LYP/6-31G** level of theory. The driving force of electron injection (ΔG (inject)), relative driving force of electron injection (ΔG r (inject)), electronic coupling constants (|VRP|) and light harvesting efficiency (LHE) of all six compounds were calculated and compared with previously studied sensitizers. The ΔG (inject), ΔG r (inject) and |VRP| of all six compounds revealed that these sensitizers would be efficient dye-sensitized solar cell materials. Cis/Trans-SQ3 exhibited superior LHE as compared to other derivatives. The Cis/Trans geometric effect was studied and discussed with regard to electro-optical and charge transport properties.

  2. Ultrafast Electron Transfer Between Dye and Catalyst on a Mesoporous NiO Surface.

    Science.gov (United States)

    Brown, Allison M; Antila, Liisa J; Mirmohades, Mohammad; Pullen, Sonja; Ott, Sascha; Hammarström, Leif

    2016-07-01

    The combination of molecular dyes and catalysts with semiconductors into dye-sensitized solar fuel devices (DSSFDs) requires control of efficient interfacial and surface charge transfer between the components. The present study reports on the light-induced electron transfer processes of p-type NiO films cosensitized with coumarin C343 and a bioinspired proton reduction catalyst, [FeFe](mcbdt)(CO)6 (mcbdt = 3-carboxybenzene-1,2-dithiolate). By transient optical spectroscopy we find that ultrafast interfacial electron transfer (τ ≈ 200 fs) from NiO to the excited C343 ("hole injection") is followed by rapid (t1/2 ≈ 10 ps) and efficient surface electron transfer from C343(-) to the coadsorbed [FeFe](mcbdt)(CO)6. The reduced catalyst has a clear spectroscopic signature that persists for several tens of microseconds, before charge recombination with NiO holes occurs. The demonstration of rapid surface electron transfer from dye to catalyst on NiO, and the relatively long lifetime of the resulting charge separated state, suggests the possibility to use these systems for photocathodes on DSSFDs.

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

    Energy Technology Data Exchange (ETDEWEB)

    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).

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

    Science.gov (United States)

    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.

  5. Volume scanning electron microscopy for imaging biological ultrastructure.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  7. Spinning Carbon Nanotube Nanothread under a Scanning Electron Microscope

    Directory of Open Access Journals (Sweden)

    Mark Schulz

    2011-08-01

    Full Text Available Nanothread with a diameter as small as one hundred nanometers was manufactured under a scanning electron microscope. Made directly from carbon nanotubes, and inheriting their superior electrical and mechanical properties, nanothread may be the world’s smallest man-made fiber. The smallest thread that can be spun using a bench-top spinning machine is about 5 microns in diameter. Nanothread is a new material building block that can be used at the nanoscale or plied to form yarn for applications at the micro and macro scales. Preliminary electrical and mechanical properties of nanothread were measured. The resistivity of nanothread is less than 10−5 Ω∙m. The strength of nanothread is greater than 0.5 GPa. This strength was obtained from measurements using special glue that cures in an electron microscope. The glue weakened the thread, thus further work is needed to obtain more accurate measurements. Nanothread will have broad applications in enabling electrical components, circuits, sensors, and tiny machines. Yarn can be used for various macroscale applications including lightweight antennas, composites, and cables.

  8. Synthesis and evaluation of changes induced by solvent and substituent in electronic absorption spectra of some azo disperse dyes.

    Science.gov (United States)

    Mohammadi, Asadollah; Yazdanbakhsh, Mohammad Reza; Farahnak, Lahya

    2012-04-01

    Five azo disperse dyes were prepared by diazotizing 4'-aminoacetophenone and p-anisidine and coupling with varies N-alkylated aromatic amines. Characterization of the dyes was carried out by using UV-vis, FTIR and 1H NMR spectroscopic techniques. The electronic absorption spectra of dyes are determined at room temperature in fifteen solvents with different polarities. The solvent dependent maximum absorption band shifts, were investigated using dielectric constant (ɛ), refractive index (n) and Kamlet-Taft polarity parameters (hydrogen bond donating ability (α), hydrogen bond accepting ability (β) and dipolarity/polarizability polarity scale (π*)). Acceptable agreement was found between the maximum absorption band of dyes and solvent polarity parameters especially with π*. The effect of substituents of coupler and/or diazo component on the color of dyes was investigated. The effects of acid and base on the visible absorption maxima of the dyes are also reported.

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

    Science.gov (United States)

    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.

  10. Structural, Morphological, and Electron Transport Studies of Annealing Dependent In2O3 Dye-Sensitized Solar Cell

    Directory of Open Access Journals (Sweden)

    S. Mahalingam

    2015-01-01

    Full Text Available Indium oxide (In2O3 thin films annealed at various annealing temperatures were prepared by using spin-coating method for dye-sensitized solar cells (DSSCs. The objective of this research is to enhance the photovoltaic conversion efficiency in In2O3 thin films by finding the optimum annealing temperature and also to study the reason for high and low performance in the annealed In2O3 thin films. The structural and morphological characteristics of In2O3 thin films were studied via XRD patterns, atomic force microscopy (AFM, field-emission scanning electron microscopy (FESEM, EDX sampling, and transmission electron microscopy (TEM. The annealing treatment modified the nanostructures of the In2O3 thin films viewed through FESEM images. The In2O3-450°C-based DSSC exhibited better photovoltaic performance than the other annealed thin films of 1.54%. The electron properties were studied by electrochemical impedance spectroscopy (EIS unit. The In2O3-450°C thin films provide larger diffusion rate, low recombination effect, and longer electron lifetime, thus enhancing the performance of DSSC.

  11. Enhanced anaerobic fermentation with azo dye as electron acceptor: simultaneous acceleration of organics decomposition and azo decolorization.

    Science.gov (United States)

    Li, Yang; Zhang, Yaobin; Quan, Xie; Zhang, Jingxin; Chen, Shuo; Afzal, Shahzad

    2014-10-01

    Accumulation of hydrogen during anaerobic processes usually results in low decomposition of volatile organic acids (VFAs). On the other hand, hydrogen is a good electron donor for dye reduction, which would help the acetogenic conversion in keeping low hydrogen concentration. The main objective of the study was to accelerate VFA composition through using azo dye as electron acceptor. The results indicated that the azo dye serving as an electron acceptor could avoid H2 accumulation and accelerate anaerobic digestion of VFAs. After adding the azo dye, propionate decreased from 2400.0 to 689.5mg/L and acetate production increased from 180.0 to 519.5mg/L. It meant that the conversion of propionate into acetate was enhanced. Fluorescence in situ hybridization analysis showed that the abundance of propionate-utilizing acetogens with the presence of azo dye was greater than that in a reference without azo dye. The experiments via using glucose as the substrate further demonstrated that the VFA decomposition and the chemical oxygen demand (COD) removal increased by 319.7mg/L and 23.3% respectively after adding the azo dye. Therefore, adding moderate azo dye might be a way to recover anaerobic system from deterioration due to the accumulation of H2 or VFAs.

  12. Kinetics of electron recombination of dye-sensitized solar cells based on TiO2 nanorod arrays sensitized with different dyes.

    Science.gov (United States)

    Wang, Hongxia; Liu, Meinan; Zhang, Min; Wang, Peng; Miura, Hidetoshi; Cheng, Yan; Bell, John

    2011-10-14

    The performance and electron recombination kinetics of dye-sensitized solar cells based on TiO(2) films consisting of one-dimensional nanorod arrays (NR-DSSCs) which are sensitized with dyes N719, C218 and D205, respectively, have been studied. It has been found that the best efficiency is obtained with the dye C218 based NR-DSSCs, benefiting from a 40% higher short-circuit photocurrent density. However, the open circuit photovoltage of the N719 based cell is 40 mV higher than that of the organic dye C218 and D205 based devices. Investigation of the electron recombination kinetics of the NR-DSSCs has revealed that the effective electron lifetime, τ(n), of the different dye based NR-DSSCs shows the sequence of C218 > D205 > N719. The higher V(oc) with the N719 based NR-DSSC is originated from the more negative energy level of the conduction band of the TiO(2) film. In addition, in comparison to the DSSCs with the conventional nanocrystalline particles based TiO(2) films, the NR-DSSCs have shown over two orders of magnitude higher τ(n) when employing N719 as the sensitizer. Nevertheless, the τ(n) of the DSSCs with the C218 based nanorod arrays is only ten-fold higher than that of the nanoparticles based devices. The remarkable characteristic of the dye C218 in suppressing the electron recombination of DSSCs is discussed.

  13. Investigation of the Remineralization Effect Tnrough Scanning Electron Microscopy

    Directory of Open Access Journals (Sweden)

    Damyanova Dobrinka M

    2016-05-01

    Full Text Available Background: Local fluoride varnishes have been widely used as a method of non-operative treatment and for caries preventive interventions for more than three decades. Purpose: Evaluation of the remineralization effect by means of electron microscopy of mineralization varnish - Clinpro ™ White Varnish with TCP (Tri-Calcium phosphate (3M. Materials and Methods: The material used is from 20 temporary intact teeth, extracted due to physiological change with permanent teeth, with a completely preserved structure and anatomy of crowns and fully physiologically resorbed roots. For the purposes of the study a scanning electron microscope JEOL JSM 6390 is used with an attachment for element analysis (EDS INCA of Oxford. Prepared samples are pre-coated with gold (cathode sputtering with apparatus JEOL JFC – 1200 to obtain a better contrast of the SEM image of early carious lesions on the smooth surfaces of the temporary teeth, with predilection for development of caries with a d1 threshold. For this purpose the two processes were monitored occurring continuously on the enamel surfacede- and remineralization. Performed was computer processing of the digital images. Results: There is presence of certain minerals deposited in the embossed enamel prisms after of remineralization. The chemical analysis established the presence of calcium (Ca2 + , around the organic matrix. Demineralised surface has pores present of around 1%, which is visible through the enamel on the surface of the deciduous teeth looking like filled and pores looking like partially covered, filled with newly formed and growing crystals. The crystals, which are hydroxylapatite, fluorapatite or fluorhydroxiapatite gradually connect, growing and forming mineral structure filling the microscopi defects and the pores from the demineralisation in the surface enamel prismless layer

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

    Science.gov (United States)

    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

  15. Scanning electron microscopy investigations regarding Adonis vernalis L. flower morphology

    Directory of Open Access Journals (Sweden)

    Irina Neta GOSTIN

    2009-11-01

    Full Text Available The floral morphology of Adonis vernalis L. was observed with a scanning electron microscope (SEM. The investigations are important to clarify some taxonomical problems and also could provide useful diagnostic elements for the identification of this medicinal plant in powdered materials. All floral organs are initiated spirally and centripetally and develop centripetally. The petals (8-12 are shorter than the sepals (5-6 in early developmental stages. The petals are disposed on spiral (with 3-4 whorls. The stamens (numerous are unbranched and reach maturity centripetally; they are free of the perianth. The anther walls consisting of a single layer epidermis in the anther wall surrounding the sporagenous tissue, one row of endothecium, two to four rows of middle layer and one row of tapetum layer. In the anther walls, the tapetal cells, by glandular type, persist later in ontogenesis. Pollen grains are tricolpate with echinate surface. The gynoecium is multiple, apocarpous with distinct carpels. The carpels are ascidiate from the beginning. At the base of each carpel, numerousness short, unicellular, trichomes are present. The stigma differentiates as two crests along the ventral slit of the ovary. Each carpel contains a single ovule inside the ovary cavity. The mature ovule is anatropous, with two integuments. It is almost parallel to the funicle.

  16. Plinia edulis - leaf architecture and scanning electron micrographs

    Directory of Open Access Journals (Sweden)

    Ana M. Donato

    2013-06-01

    Full Text Available Many species of Myrtaceae, including Plinia edulis (Vell. Sobral (cambucá, have pharmacological properties and are used as hypoglycemiants and therapeutic agents against stomach problems and throat infections. Samples were collected from Tijuca Forest in Rio de Janeiro, and the morpho-anatomical data were compared with other specimens obtained from Trindade, Paraty, found in the literature. Variations in leaf anatomy were observed, and the possible causes for these effects are discussed. The plant material collected from Tijuca Forest was analyzed using scanning electron and optical microscopy. Histochemical tests were applied to identify starch, lipids, phenolic compounds and lignin. The epidermal cells exhibit straight or slightly sinuous anticlinal walls covered by a smooth cuticle with granules of wax. Simple trichomes are restricted to the midrib region, and paracytic stomata are only observed on the abaxial leaf surface. The mesophyll is dorsiventral, with conspicuous intercellular spaces in the spongy parenchyma. Intercalated columns of crystalliferous cells and subepidermal secretory cavities are observed in the single layer of palisade parenchyma. The samples obtained from Trindade, Paraty, show larger leaves, anomocytic stomata and trichomes scattered throughout the leaf surface. This plasticity might reflect leaf adaptations to environmental factors or different stages of leaf development.

  17. Scanning electron microscopy of the neuropathology of murine cerebral malaria

    Directory of Open Access Journals (Sweden)

    Brenneis Christian

    2006-11-01

    Full Text Available Abstract Background The mechanisms leading to death and functional impairments due to cerebral malaria (CM are yet not fully understood. Most of the knowledge about the pathomechanisms of CM originates from studies in animal models. Though extensive histopathological studies of the murine brain during CM are existing, alterations have not been visualized by scanning electron microscopy (SEM so far. The present study investigates the neuropathological features of murine CM by applying SEM. Methods C57BL/6J mice were infected with Plasmodium berghei ANKA blood stages. When typical symptoms of CM developed perfused brains were processed for SEM or light microscopy, respectively. Results Ultrastructural hallmarks were disruption of vessel walls, parenchymal haemorrhage, leukocyte sequestration to the endothelium, and diapedesis of macrophages and lymphocytes into the Virchow-Robin space. Villous appearance of observed lymphocytes were indicative of activated state. Cerebral oedema was evidenced by enlargement of perivascular spaces. Conclusion The results of the present study corroborate the current understanding of CM pathophysiology, further support the prominent role of the local immune system in the neuropathology of CM and might expose new perspectives for further interventional studies.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lunov, O., E-mail: lunov@fzu.cz; Churpita, O.; Zablotskii, V.; Jäger, A.; Dejneka, A. [Institute of Physics AS CR, Prague 18221 (Czech Republic); Deyneka, I. G.; Meshkovskii, I. K. [St. Petersburg State University of Information Technologies, Mechanics and Optics, St. Petersburg 197101 (Russian Federation); Syková, E. [Institute of Experimental Medicine AS CR, Prague 14220 (Czech Republic); Kubinová, Š. [Institute of Physics AS CR, Prague 18221 (Czech Republic); Institute of Experimental Medicine AS CR, Prague 14220 (Czech Republic)

    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. Somatic Embryos in Catharanthus roseus: A Scanning Electron Microscopic Study

    Directory of Open Access Journals (Sweden)

    Junaid ASLAM

    2014-06-01

    Full Text Available Catharanthus roseus (L. G. Don is an important medicinal plant as it contains several anti-cancerous compounds, like vinblastine and vincristine. Plant tissue culture technology (organogenesis and embryogenesis has currently been used in fast mass propagating raw materials for secondary metabolite synthesis. In this present communication, scanning electron microscopic (SEM study of somatic embryos was conducted and discussed. The embryogenic callus was first induced from hypocotyls of in vitro germinated seeds on which somatic embryos, differentiated in numbers, particularly on 2,4-D (1.0 mg/L Murashige and Skoog (MS was medium. To understand more about the regeneration method and in vitro formed embryos SEM was performed. The SEM study revealed normal somatic embryo origin and development from globular to heart-, torpedo- and then into cotyledonary-stage of embryos. At early stage, the embryos were clustered together in a callus mass and could not easily be detached from the parental tissue. The embryos were often long cylindrical structure with or without typical notch at the tip. Secondary embryos were also formed on primary embryo structure. The advanced cotyledonary embryos showed prominent roots and shoot axis, which germinated into plantlets. The morphology, structure and other details of somatic embryos at various stages were presented.

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

    Science.gov (United States)

    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.

  1. Char porosity characterisation by scanning electron microscopy and image analysis

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, H.S.; Rosenberg, P.; Petersen, H.I.; Soerensen, L.H. [Danfoss A/S, Nordborg (Denmark)

    2000-09-01

    No significant change in either the morphotype composition or the macroporosity (pores {gt}5 {mu}m) in the 0-30 wt.% char burnout interval were revealed by reflected light microscopy or image analysis. Two high temperature char series from a Tertiary South American coal (C1) and a Permian Gondwana coal (C2) were therefore examined by scanning electron microscopy to provide information on the combustion process up to {approximately} 60 wt% char burnout. This study documents a significant mesopore ({approximately} 0.1-5 {mu}m) development on the fused chars in the burnout interval studied. A method to quantify the size and amount of the mesopores is described and both the parameters increased with increasing char burnout. Above a char burnout of {approximately} 30 wt% an increase in macroporosity was detected and ascribed to coalescence of mesopores to form large pores. Although the measurement of mesoporosity is restricted to fused chars, i.e. pores in fragments and the char morphotypes inertoid, fusinoid and solid could not be measured, the consideration of mesoporosity seems to be fundamental in understanding, evaluating and modelling combustion processes in the char burnout interval studied. 7 refs., 9 figs., 4 tabs.

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

    Science.gov (United States)

    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.

  3. Scanning electron microscopy of xiphinema, longidorus, and californidorus stylet morphology.

    Science.gov (United States)

    Cho, M R; Robbins, R T

    1990-04-01

    Stylet ultrastructure of five Xiphinema, four Longidorus, and three Californidorus species was compared by scanning electron microscopy. Morphological differences were seen in the odontophores and odontostyle bases between the genera and some of the species. All Xiphinema studied had well-developed odontophore flanges; the Longidorus species lacked flanges, except for weakly developed ones in L. diadecturus; and none of the Californidorus had flanges. Three sinuses were present in the odontophores of all species. The sinuses varied in length depending upon species. In Xiphinema and Californidorus the odontostyle bases had distinct overlapping collars, but in Longidorus the collars were absent except for L. diadecturus. The odontostyle-odontophore junction from a lateral view appeared as a slanted transverse line in all the species, but in a dorsal view of Xiphinema and Californidorus it was V-shaped. Dorsal longitudinal seams of the odontostyle and odontophore were observed in all the species. The dorsally located odontostyle aperture was ca. 1 mum from the anterior end in all species, except in one Longidorus sp. it was ca. 4 mum from the end.

  4. An overview on bioaerosols viewed by scanning electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wittmaack, K. [GSF-National Research Centre for Environment and Health, Institute of Radiation Protection, 85758 Neuherberg (Germany)]. E-mail: wittmaack@gsf.de; Wehnes, H. [GSF-National Research Centre for Environment and Health, Institute of Pathology, 85758 Neuherberg (Germany); Heinzmann, U. [GSF-National Research Centre for Environment and Health, Institute of Pathology, 85758 Neuherberg (Germany); Agerer, R. [Ludwig-Maximilians University Munich, Department Biology, Biodiversity Research: Mycology, Menzinger Stasse 67, 80638 Munich (Germany)

    2005-06-15

    Bioaerosols suspended in ambient air were collected with single-stage impactors at a semiurban site in southern Germany during late summer and early autumn. Sampling was mostly carried out at a nozzle velocity of 35 m/s, corresponding to a minimum aerodynamic diameter (cut-off diameter) of aerosol particles of 0.8 {mu}m. The collected particles, sampled for short periods ({approx}15 min) to avoid pile-up, were characterized by scanning electron microscopy (SEM). The observed bioaerosols include brochosomes, fungal spores, hyphae, insect scales, hairs of plants and, less commonly, bacteria and epicuticular wax. Brochosomes, which serve as a highly water repellent body coating of leafhoppers, are hollow spheroids with diameters around 400 nm, resembling C{sub 60} or footballs (soccer balls). They are usually airborne not as individuals but in the form of large clusters containing up to 10,000 individual species or even more. Various types of spores and scales were observed, but assignment turned out be difficult due to the large number of fungi and insects from which they may have originated. Pollens were observed only once. The absence these presumably elastic particles suggests that they are frequently lost, at the comparatively high velocities, due to bounce-off from the nonadhesive impaction surfaces.

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

    Science.gov (United States)

    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.

  6. Scanning electron microscopy applied to seed-borne fungi examination.

    Science.gov (United States)

    Alves, Marcelo de Carvalho; Pozza, Edson Ampélio

    2009-07-01

    The aim of this study was to test the standard scanning electron microscopy (SEM) as a potential alternative to study seed-borne fungi in seeds, by two different conditions of blotter test and water restriction treatment. In the blotter test, seeds were subjected to conditions that enabled pathogen growth and expression, whereas the water restriction method consisted in preventing seed germination during the incubation period, resulting in the artificial inoculation of fungi. In the first condition, seeds of common bean (Phaseolus vulgaris L.), maize (Zea mays L.), and cotton (Gossypium hirsutum L.) were submitted to the standard blotter test and then prepared and observed with SEM. In the second condition, seeds of cotton (G. hirsutum), soybean (Glycine max L.), and common bean (P. vulgaris L.) were, respectively, inoculated with Colletotrichum gossypii var. cephalosporioides, Colletotrichum truncatum, and Colletotrichum lindemuthianum by the water restriction technique, followed by preparation and observation with SEM. The standard SEM methodology was adopted to prepare the specimens. Considering the seeds submitted to the blotter test, it was possible to identify Fusarium sp. on maize, C. gossypii var. cephalosporioides, and Fusarium oxysporum on cotton, Aspergillus flavus, Penicillium sp., Rhizopus sp., and Mucor sp. on common bean. Structures of C. gossypii var. cephalosporioides, C. truncatum, and C. lindemuthianum were observed in the surface of inoculated seeds. (c) 2009 Wiley-Liss, Inc.

  7. Cold Pad-Batch dyeing method for cotton fabric dyeing with reactive dyes using ultrasonic energy.

    Science.gov (United States)

    Khatri, Zeeshan; Memon, Muhammad Hanif; Khatri, Awais; Tanwari, Anwaruddin

    2011-11-01

    Reactive dyes are vastly used in dyeing and printing of cotton fibre. These dyes have a distinctive reactive nature due to active groups which form covalent bonds with -OH groups of cotton through substitution and/or addition mechanism. Among many methods used for dyeing cotton with reactive dyes, the Cold Pad Batch (CPB) method is relatively more environment friendly due to high dye fixation and non requirement of thermal energy. The dyed fabric production rate is low due to requirement of at least twelve hours batching time for dye fixation. The proposed CPB method for dyeing cotton involves ultrasonic energy resulting into a one third decrease in batching time. The dyeing of cotton fibre was carried out with CI reactive red 195 and CI reactive black 5 by conventional and ultrasonic (US) method. The study showed that the use of ultrasonic energy not only shortens the batching time but the alkalis concentrations can considerably be reduced. In this case, the colour strength (K/S) and dye fixation (%F) also enhances without any adverse effect on colour fastness of the dyed fabric. The appearance of dyed fibre surface using scanning electron microscope (SEM) showed relative straightening of fibre convolutions and significant swelling of the fibre upon ultrasonic application. The total colour difference values ΔE (CMC) for the proposed method, were found within close proximity to the conventionally dyed sample.

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

    Science.gov (United States)

    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.

  9. Electron beam heating effects during environmental scanning electron microscopy imaging of water condensation on superhydrophobic surfaces

    Science.gov (United States)

    Rykaczewski, K.; Scott, J. H. J.; Fedorov, A. G.

    2011-02-01

    Superhydrophobic surfaces (SHSs) show promise as promoters of dropwise condensation. Droplets with diameters below ˜10 μm account for the majority of the heat transferred during dropwise condensation but their growth dynamics on SHS have not been systematically studied. Due to the complex topography of the surface environmental scanning electron microscopy is the preferred method for observing the growth dynamics of droplets in this size regime. By studying electron beam heating effects on condensed water droplets we establish a magnification limit below which the heating effects are negligible and use this insight to study the mechanism of individual drop growth.

  10. Optical nonlinearity of organic dyes as studied by Z-scan and transient grating techniques

    Indian Academy of Sciences (India)

    Umakanta Tripathy; R Justin Rajesh; Prem B Bisht; A Subrahamanyam

    2002-12-01

    The excited state absorption cross-section of 5,5′-dichloro-11-diphenylamino- 3,3′-diethyl-10,12-ethylinethiatricarbocyanine perchlorate (IR140) have been measured by using a single beam transmission technique. Z-scan experiments have been used to find out a few nonlinear parameters. The excited state relaxation times have also been measured by using laser induced transient grating (LITG) technique.

  11. Energy and Electron Transfer Cascade in Self-Assembled Bilayer Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Ogunsolu, Omotola Olukemi; Murphy, Ian A; Wang, Jamie C; Das, Anjan; Hanson, Kenneth

    2016-10-04

    Current high efficiency dye-sensitized solar cells (DSSCs) rely on the incorporation of multiple chromophores, via either co-deposition or pre-formed assemblies, as a means of increasing broad band light absorption. These strategies have some inherent limitations including decreased total light absorption by each of the dyes, low surface loadings, and complex synthetic procedures. In this report, we introduce an alternative strategy, self-assembled bilayers, as a simple, step-wise method of incorporating two complementary chromophores into a DSSC. The bilayer devices exhibit a 10% increase in Jsc, Voc and η over the monolayer devices due to increased incident photon-to-electron conversion efficiency across the entire visible spectrum and slowed recombination losses at the interface. Directional energy and electron transfer towards the metal oxide surface are key steps in the bilayer photon-to-current generation process. These results are important as they open the door to a new architecture for harnessing broad band light in dye-sensitized devices.

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

    Science.gov (United States)

    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.

  13. Scanning Transmission X-Ray, Laser Scanning, and Transmission Electron Microscopy Mapping of the Exopolymeric Matrix of Microbial Biofilms

    OpenAIRE

    Lawrence, J. R.; Swerhone, G. D. W.; Leppard, G. G.; T. Araki; Zhang, X.; West, M. M.; A. P. Hitchcock

    2003-01-01

    Confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and soft X-ray scanning transmission X-ray microscopy (STXM) were used to map the distribution of macromolecular subcomponents (e.g., polysaccharides, proteins, lipids, and nucleic acids) of biofilm cells and matrix. The biofilms were developed from river water supplemented with methanol, and although they comprised a complex microbial community, the biofilms were dominated by heterotrophic bacteria. TEM provid...

  14. Visualization of Microbial Biomarkers by Scanning Electron Microscopy

    Science.gov (United States)

    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. Visualization of Microbial Biomarkers by Scanning Electron Microscopy

    Science.gov (United States)

    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.

  16. Environmental scanning electron microscopy of hydrated conditioned/etched dentine.

    Science.gov (United States)

    de Wet, F A; van der Vyver, P J; Eick, J D; Dusevich, V M

    2000-11-01

    Various etchants/conditioners are used during dental treatment to affect or remove the smear layer. The purpose of this study was to evaluate the effect of different treatments on moist dentine, using a field emission environmental scanning electron microscope (FE-ESEM). Twenty freshly extracted, human molar teeth were utilised. The roots and pulps were removed, and the crowns horizontally sectioned with a low speed diamond saw (Isomet) (with cooling in a saline solution) in order to expose superficial dentine. A smear layer was created on these surfaces by using 600 grit silicone carbide paper. Test surfaces were then treated in one of the following ways: 1. 37% phosphoric acid liquid 2. 37% phosphoric acid gel 3. NRC (non-rinse conditioner) without rinsing 4. NRC with rinsing. Shallow grooves were cut on the untreated sides, using a thin diamond bur. This enabled the samples to be split in half when pressure was applied in the grooves. Samples were maintained moist throughout specimen preparation. Samples were examined in the FE-ESEM (Philips XL 30) in such a way that the effect of the treatment could be viewed occlusally, as well as perpendicular to the treated interface. Phosphoric acid liquid and gel removed the smear layer, and demineralised the dentine for approximately 5-10 micrometers. NRC penetrated the smear layer and modified it to a lesser degree. However, washing of the NRC treated surface removed part of the smear layer, and opened up some dentinal tubules. Excellent resolution was possible with the FE-ESEM in both the wet and dry modes.

  17. Scanning electron microscopy of hair treated in hard water.

    Science.gov (United States)

    Srinivasan, Gautham; Chakravarthy Rangachari, Srinivas

    2016-06-01

    Hardness of water is determined by the amount of calcium carbonate (CaCO3 ) and magnesium sulfate (MgSO4 ) dissolved in it. Hardness of water used for washing hair may damage the hair. The objective of this study is to observe the surface changes due to hard water usage and compare the thickness of hair between hard and soft water treated samples. Ten to 15 hair strands of length 15-20 cm, which were lost during combing, were obtained from 15 healthy female volunteers. Each hair sample was cut into two equal halves to obtain two sets per volunteer. Each hair sample was wrapped around a glass rod. One set of 15 samples was washed with hard water, and the other set was washed with distilled water for 10 minutes on alternate days and air-dried. This procedure was carried out for 30 days. The surface of hair treated in hard and soft water was examined under a scanning electron microscope. The CaCO3 and MgSO4 content of hard and distilled water samples were determined as 212.5 ppm of CaCO3 and 10 ppm of CaCO3 respectively. The mean calcium deposition in hard and distilled water treated hair was determined as 0.804% and 0.26%, respectively. The mean magnesium deposition in hard and distilled water treated hair was determined as 0.34% and 0.078%, respectively. The mean thickness of hair treated in hard water and distilled water were 72.78 and 78.14 μm, respectively. The surface of hard water treated hair has a ruffled appearance with higher mineral deposition and decreased thickness when compared with the surface of distilled water treated hair. © 2015 The International Society of Dermatology.

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

    Directory of Open Access Journals (Sweden)

    Suhyun Kim

    2014-10-01

    Full Text Available 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 CoSi2 source and drain. Nanometer-scale SMFs were formed with a scanning grating size of ds at integer multiples of the Si crystal lattice spacing dl (ds ∼ ndl, 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%.

  19. An image acquisition system built with a modular frame grabber for scanning electron microscopes

    Energy Technology Data Exchange (ETDEWEB)

    Ruan, S. [The Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Kapp, O.H. [The Department of Radiology and The Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637 (United States)

    1995-09-01

    We have built an image acquisition and processing system based on a modular frame grabber board (MFG) for use with scanning (or scanning transmission) electron microscopes. The variable-scan acquisition module of the grabber board provides compatibility with electron microscopes processing various scan speeds, e.g., the very slow scan rate of our mirror-type electron microscope. In addition to the acquisition function, the board provides many image processing capabilities. A special time-base unit was built to synchronize the acquisition system with the scanning system on the electron microscope. A Windows application has been built to operate the MFG as well as manage all functions of the electron microscope. Using this approach we have been able to greatly simplify the task of digital image acquisition as well as creating a powerful and seamless interface to our Windows-based environment. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  20. One electron changes everything: a multispecies copper redox shuttle for dye-sensitized solar cells.

    Energy Technology Data Exchange (ETDEWEB)

    Hoffeditz, William L.; Katz, Michael J.; Deria, Pravas; Cutsail, George E.; Pellin, Michael J.; Farha, Omar K.; Hupp, Joseph T.

    2016-02-25

    Dye-sensitized solar cells (DSCs) are an established alternative photovoltaic technology that offers numerous potential advantages in solar energy applications. However, this technology has been limited by the availability of molecular redox couples that are both noncorrosive/nontoxic and do not diminish the performance of the device. In an effort to overcome these shortcomings, a copper-containing redox shuttle derived from 1,8-bis(2'-pyridyl)-3,6-dithiaoctane (PDTO) ligand and the common DSC additive 4-tert-butylpyridine (TBP) was investigated. Electrochemical measurements, single-crystal X-ray diffraction, and absorption and electron paramagnetic resonance spectroscopies reveal that, upon removal of one metal-centered electron, PDTO-enshrouded copper ions completely shed the tetradentate PDTO ligand and replace it with four or more TBP ligands. Thus, the Cu(I) and Cu(II) forms of the electron shuttle have completely different coordination spheres and are characterized by widely differing Cu(II/I) formal potentials and reactivities for forward versus reverse electron transfer. Notably, the coordination-sphere replacement process is fully reversed upon converting Cu(II) back to Cu(I). In cells featuring an adsorbed organic dye and a nano- and mesoparticulate, TiO2-based, photoelectrode, the dual species redox shuttle system engenders performance superior to that obtained with shuttles based on the (II/I) forms of either of the coordination complexes in isolation.

  1. The sinusoidal lining cells in "normal" human liver. A scanning electron microscopic investigation

    DEFF Research Database (Denmark)

    Horn, T; Henriksen, Jens Henrik Sahl; Christoffersen, P

    1986-01-01

    The scanning electron microscopic was used to study the fenestrations of human liver sinusoids. Thirteen biopsies, where light microscopy and transmission electron microscopy revealed normal sinusoidal architecture, were investigated. The number of fenestrae was calculated in acinar zone 3...

  2. Sparse sampling and reconstruction for electron and scanning probe microscope imaging

    Science.gov (United States)

    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.

  3. Sparse sampling and reconstruction for electron and scanning probe microscope imaging

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. Batchwise dyeing of bamboo cellulose fabric with reactive dye using ultrasonic energy.

    Science.gov (United States)

    Larik, Safdar Ali; Khatri, Awais; Ali, Shamshad; Kim, Seong Hun

    2015-05-01

    Bamboo is a regenerated cellulose fiber usually dyed with reactive dyes. This paper presents results of the batchwise dyeing of bamboo fabric with reactive dyes by ultrasonic (US) and conventional (CN) dyeing methods. The study was focused at comparing the two methods for dyeing results, chemicals, temperature and time, and effluent quality. Two widely used dyes, CI Reactive Black 5 (bis-sulphatoethylsulphone) and CI Reactive Red 147 (difluorochloropyrimidine) were used in the study. The US dyeing method produced around 5-6% higher color yield (K/S) in comparison to the CN dyeing method. A significant savings in terms of fixation temperature (10°C) and time (15 min), and amounts of salt (10 g/L) and alkali (0.5-1% on mass of fiber) was realized. Moreover, the dyeing effluent showed considerable reductions in the total dissolved solids content (minimum around 29%) and in the chemical oxygen demand (minimum around 13%) for the US dyebath in comparison to the CN dyebath. The analysis of colorfastness tests demonstrated similar results by US and CN dyeing methods. A microscopic examination on the field emission scanning electron microscope revealed that the US energy did not alter the surface morphology of the bamboo fibers. It was concluded that the US dyeing of bamboo fabric produces better dyeing results and is a more economical and environmentally sustainable method as compared to CN dyeing method.

  5. Electronic Single Molecule Measurements with the Scanning Tunneling Microscope

    Science.gov (United States)

    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

  6. Observation of the sweating in lipstick by scanning electron microscopy.

    Science.gov (United States)

    Seo, S Y; Lee, I S; Shin, H Y; Choi, K Y; Kang, S H; Ahn, H J

    1999-06-01

    The relationship between the wax matrix in lipstick and sweating has been investigated by observing the change of size and shape of the wax matrix due to sweating by Scanning Electron Microscopy (SEM). For observation by SEM, a lipstick sample was frozen in liquid nitrogen. The oil in the lipstick was then extracted in cold isopropanol (-70 degrees C) for 1-3 days. After the isopropanol was evaporated, the sample was sputtered with gold and examined by SEM. The change of wax matrix underneath the surface from fine, uniform structure to coarse, nonuniform structure resulted from the caking of surrounding wax matrix. The oil underneath the surface migrated to the surface of lipstick with sweating; consequently the wax matrix in that region was rearranged into the coarse matrix. In case of flamed lipstick, sweating was delayed and the wax matrix was much coarser than that of the unflamed one. The larger wax matrix at the surface region was good for including oil. The effect of molding temperature on sweating was also studied. As the molding temperature rose, sweating was greatly reduced and the size of the wax matrix increased. It was found that sweating was influenced by the compatibility of wax and oil. A formula consisting of wax and oil that have good compatibility has a tendency to reduce sweating and increase the size of the wax matrix. When pigments were added to wax and oil, the size of the wax matrix was changed, but in all cases sweating was increased due to the weakening of the binding force between wax and oil. On observing the thick membrane of wax at the surface of lipstick a month after molding it was also found that sweating was influenced by ageing. In conclusion, the structure of the wax matrix at the surface region of lipstick was changed with the process of flaming, molding temperature, compatibility of wax and oil, addition of pigment, and ageing. In most cases, as the size of the wax matrix was increased, sweating was reduced and delayed.

  7. Patterned 3-dimensional metal grid electrodes as alternative electron collectors in dye-sensitized solar cells.

    Science.gov (United States)

    Chua, Julianto; Mathews, Nripan; Jennings, James R; Yang, Guangwu; Wang, Qing; Mhaisalkar, Subodh G

    2011-11-21

    We describe the application of 3-dimensional metal grid electrodes (3D-MGEs) as electron collectors in dye-sensitized solar cells (DSCs) as a replacement for fluorinated tin oxide (FTO) electrodes. Requirements, structure, advantages, and limitations of the metal grid electrodes are discussed. Solar conversion efficiencies of 6.2% have been achieved in 3D-MGE based solar cells, comparable to that fabricated on FTO (7.1%). The charge transport properties and collection efficiencies in these novel solar cells have been studied using electrochemical impedance spectroscopy.

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

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakaran, Ramprashad [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rhodes, Mark A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schemer-Kohrn, Alan L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Guzman, Anthony D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakaran, Ramprashad [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rhodes, Mark A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schemer-Kohrn, Alan L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Guzman, Anthony D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    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.

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

    Science.gov (United States)

    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.

  11. Imaging and analysis of subsurface Cu interconnects by detecting backscattered electrons in the scanning electron microscope

    Science.gov (United States)

    Gignac, L. M.; Kawasaki, M.; Boettcher, S. H.; Wells, O. C.

    2005-06-01

    Cu -SiO2-SiNx interconnects that were located 0.65-2.7-μm below the surface of silicon-integrated circuits were imaged in a scanning electron microscope and a transmission electron microscope with a scanning attachment by detecting backscattered electrons (BSEs) with an incident electron-beam energy (Eo) in the range of 30-400keV. BSE images could be used to detect voids in subsurface Cu interconnects, even in regions covered with upper level Cu lines or vias. As Eo was increased from 30to400keV, structures could be seen as a result of atomic number (Z) contrast farther below the surface while structures closer to the surface had reduced Z contrast. The subsurface beam diameter was measured from BSE images as a function of Eo and depth below the surface. For all Eo, the subsurface beam diameter initially rapidly increased with SiO2 overlayer thickness but, for 150keV, a leveling off in the beam spread was seen for depths >1.7μm. Beam broadening affected whether the TaN /Ta liners that surrounded the Cu conductors could be seen at the edges of the lines; this contrast was observed only when the subsurface beam diameter was ⩽1.5× the liner thickness. The BSE information depth for imaging 0.2-μm-sized voids in subsurface Cu -SiO2-SiNx interconnect structures at 30 and 150keV was estimated to be 0.65 and 3μm, respectively.

  12. Computational design of molecules for dye sensitized solar cells and nano electronics

    DEFF Research Database (Denmark)

    Ørnsø, Kristian Baruël

    . This is illustrated in this thesis, where a high-throughput Density Functional Theory study of a total of 5145 porphyrin based dye molecules is presented. Initially, the structures of the dyes are optimized and the frontier energy orbital energies calculated. Following this, the dyes are scored for use in a dye...

  13. Electronically Steerable Antennas with Panoramic Scan Field of View Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Electronically steerable antennas are key to effective radio transmission at millimeter-wave frequencies. To enable communication with rovers, robots, EVA...

  14. Evaluation of the bleached human enamel by Scanning Electron Microscopy

    DEFF Research Database (Denmark)

    Miranda, Carolina Baptista; Pagani, Clovis; Benetti, Ana Raquel

    2005-01-01

    Since bleaching has become a popular procedure, the effect of peroxides on dental hard tissues is of great interest in research. Purpose: The aim of this in vitro study was to perform a qualitative analysis of the human enamel after the application of in-office bleaching agents, using Scanning El...

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

    Science.gov (United States)

    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.

  16. 6H-Indolo[2,3-b]quinoxaline-based organic dyes containing different electron-rich conjugated linkers for highly efficient dye-sensitized solar cells

    Science.gov (United States)

    Qian, Xing; Gao, Huan-Huan; Zhu, Yi-Zhou; Lu, Lin; Zheng, Jian-Yu

    2015-04-01

    A new class of organic dyes based on 6H-indolo[2,3-b]quinoxaline are synthesized and applied as photosensitizers for dye-sensitized solar cells. Different electron-rich π-conjugated bridges such as oligothiophene, thienyl carbazole, and furyl carbazole are introduced to cooperate with 6H-indolo[2,3-b]quinoxaline and cyanoacrylic acid anchoring group to give the dyes JY01, JY02, and JY03, respectively. Their photophysical, electrochemical, and photovoltaic properties are further investigated. All three dyes show good performances as photosensitizers. In particular, DSSC based on JY01 shows the best photovoltaic performance with a short-circuit photocurrent density of 16.0 mA cm-2, an open-circuit photovoltage of 708 mV and a fill factor of 0.67, corresponding to an overall power conversion efficiency of 7.62% under AM 1.5 irradiation (100 mW cm-2).

  17. Enhancing electron collection efficiency and effective diffusion length in dye-sensitized solar cells.

    Science.gov (United States)

    Wong, Daniel Kwan-Pang; Ku, Chen-Hao; Chen, Yen-Ru; Chen, Guan-Ren; Wu, Jih-Jen

    2009-10-19

    Intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy are employed to measure the dynamics of electron transport and recombination in the ZnO nanowire (NW) array-ZnO/layered basic zinc acetate (LBZA) nanoparticle (NP) composite dye-sensitized solar cells (DSSCs). The roles of the vertical ZnO NWs and insulating LBZA in the electron collection and transport in DSSCs are investigated by comparing the results to those in the TiO(2)-NP, horizontal TiO(2)-NW and vertical ZnO-NW-array DSSCs. The electron transport rate and electron lifetime in the ZnO NW/NP composite DSSC are superior to those in the conventional TiO(2)-NP cell due to the existence of the vertical ZnO NWs and insulating LBZA. It indicates that the ZnO NW/NP composite anode is able to sustain efficient electron collection over much greater thickness than the TiO(2)-NP cell does. Consequently, a larger effective electron diffusion length is available in the ZnO composite DSSC.

  18. Role of hydrogen-bonding and photoinduced electron transfer (PET) on the interaction of resorcinol based acridinedione dyes with Bovine Serum Albumin (BSA) in water

    Energy Technology Data Exchange (ETDEWEB)

    Kumaran, Rajendran, E-mail: kumaranwau@rediffmail.com [Department of Chemistry, Dwaraka Doss Goverdhan Doss, Vaishnav College (Autonomous), 833, Gokul Bagh, E.V.R. Periyar Road, Arumbakkam, Chennai 600106, Tamil Nadu (India); Vanjinathan, Mahalingam [Department of Chemistry, Dwaraka Doss Goverdhan Doss, Vaishnav College (Autonomous), 833, Gokul Bagh, E.V.R. Periyar Road, Arumbakkam, Chennai 600106, Tamil Nadu (India); Ramamurthy, Perumal [National Centre for Ultrafast Processes, University of Madras, Taramani Campus Chennai 600113, Tamil Nadu (India)

    2015-08-15

    Resorcinol based acridinedione (ADDR) dyes are a class of laser dyes and have structural similarity with purine derivatives, nicotinamide adenine dinucleotide (NADH) analogs. These dyes are classified into photoinduced electron transfer (PET) and non-photoinduced electron transfer dyes, and the photophysical properties of family of these dyes exhibiting PET behavior are entirely different from that of non-PET dyes. The PET process in ADDR dyes is governed by the solvent polarity such that an ADDR dye exhibits PET process through space in an aprotic solvent like acetonitrile and does not exhibit the same in protic solvents like water and methanol. A comparison on the fluorescence emission, lifetime and nature of interaction of various ADDR dyes with a large globular protein like Bovine Serum Albumin (BSA) was carried out in aqueous solution. The interaction of PET based ADDR dyes with BSA in water is found to be largely hydrophobic, but hydrogen-bonding interaction of BSA with dye molecule influences the fluorescence emission of the dye and shifts the emission towards red region. Fluorescence spectral studies reveal that the excited state properties of PET based ADDR dyes are largely influenced by the addition of BSA. The microenvironment around the dye results in significant change in the fluorescence lifetime and emission. Fluorescence enhancement with a red shift in the emission results after the addition of BSA to ADDR dyes containing free amino hydrogen in the 10th position of basic acridinedione dye. The amino hydrogen (N–H) in the 10th position of ADDR dye is replaced by methyl group (N–CH{sub 3}), a significant decrease in the fluorescence intensity with no apparent shift in the emission maximum was observed after the addition of BSA. The nature of interaction between ADDR dyes with BSA is hydrogen-bonding and the dye remains unbound even at the highest concentration of BSA. Circular Dichroism (CD) studies show that the addition of dye to BSA results in

  19. The Role of the Conjugate Bridge in Electronic Structures and Related Properties of Tetrahydroquinoline for Dye Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    You-Zhi Wu

    2013-03-01

    Full Text Available To understand the role of the conjugate bridge in modifying the properties of organic dye sensitizers in solar cells, the computations of the geometries and electronic structures for 10 kinds of tetrahydroquinoline dyes were performed using density functional theory (DFT, and the electronic absorption and fluorescence properties were investigated via time dependent DFT. The population analysis, molecular orbital energies, radiative lifetimes, exciton binding energies (EBE, and light harvesting efficiencies (LHE, as well as the free energy changes of electron injection ( and dye regeneration ( were also addressed. The correlation of charge populations and experimental open-circuit voltage (Voc indicates that more charges populated in acceptor groups correspond to larger Voc. The elongating of conjugate bridge by thiophene units generates the larger oscillator strength, higher LHE, larger absolute value of , and longer relative radiative lifetime, but it induces the decreasing of EBE and . So the extending of conjugate bridge with thiopene units in organic dye is an effective way to increase the harvest of solar light, and it is also favorable for electron injection due to their larger . While the inversely correlated relationship between EBE and LHE implies that the dyes with lower EBE produce more efficient light harvesting.

  20. Natural dyes adsorbed on TiO2 nanowire for photovoltaic applications: enhanced light absorption and ultrafast electron injection.

    Science.gov (United States)

    Meng, Sheng; Ren, Jun; Kaxiras, Efthimios

    2008-10-01

    We investigate the electronic coupling between a TiO2 nanowire and a natural dye sensitizer, using state-of-the-art time-dependent first-principles calculations. The model dye molecule, cyanidin, is deprotonated into the quinonoidal form upon adsorption on the wire surface. This results in its highest occupied molecular orbital (HOMO) being located in the middle of the TiO2 bandgap and its lowest unoccupied molecular orbital (LUMO) being close to the TiO2 conduction band minimum (CBM), leading to greatly enhanced visible light absorption with two prominent peaks at 480 and 650 nm. We find that excited electrons are injected into the TiO2 conduction band within a time scale of 50 fs with negligible electron-hole recombination and energy dissipation, even though the dye LUMO is located 0.1-0.3 eV lower than the CBM of the TiO2 nanowire.

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

    Science.gov (United States)

    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.

  2. A High Sensitivity IDC-Electronic Tongue Using Dielectric/Sensing Membranes with Solvatochromic Dyes

    Directory of Open Access Journals (Sweden)

    Md. Rajibur Rahaman Khan

    2016-05-01

    Full Text Available In this paper, an electronic tongue/taste sensor array containing different interdigitated capacitor (IDC sensing elements to detect different types of tastes, such as sweetness (glucose, saltiness (NaCl, sourness (HCl, bitterness (quinine-HCl, and umami (monosodium glutamate is proposed. We present for the first time an IDC electronic tongue using sensing membranes containing solvatochromic dyes. The proposed highly sensitive (30.64 mV/decade sensitivity IDC electronic tongue has fast response and recovery times of about 6 s and 5 s, respectively, with extremely stable responses, and is capable of linear sensing performance (R2 ≈ 0.985 correlation coefficient over the wide dynamic range of 1 µM to 1 M. The designed IDC electronic tongue offers excellent reproducibility, with a relative standard deviation (RSD of about 0.029. The proposed device was found to have better sensing performance than potentiometric-, cascoded compatible lateral bipolar transistor (C-CLBT-, Electronic Tongue (SA402-, and fiber-optic-based taste sensing systems in what concerns dynamic range width, response time, sensitivity, and linearity. Finally, we applied principal component analysis (PCA to distinguish between various kinds of taste in mixed taste compounds.

  3. A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Gleb Sorohhov

    2015-06-01

    Full Text Available Two new photosensitizers featured with a cyanoacrylic acid electron acceptor (A and a hybrid electron donor (D of cyclopentadithiophene and dithiafulvenyl, either directly linked or separated by a phenyl ring, were synthesized and characterized. Both of them undergo two reversible oxidations and strongly absorb in the visible spectral region due to a photo-induced intramolecular charge-transfer (ICT transition. To a great extent, the electronic interaction between the D and A units is affected by the presence of a phenyl spacer. Without a phenyl ring, the D unit appears more difficult to oxidize due to a strong electron-withdrawing effect of the A moiety. In sharp contrast, the insertion of the phenyl ring between the D and A units leads to a broken π-conjugation and therefore, the oxidation potentials remain almost unchanged compared to those of an analogue without the A group, suggesting that the electronic coupling between D and A units is relatively weak. As a consequence, the lowest-energy absorption band shows a slight hypsochromic shift upon the addition of the phenyl spacer, indicative of an increased HOMO–LUMO gap. In turn, the direct linkage of D and A units leads to an effective π-conjugation, thus substantially lowering the HOMO–LUMO gap. Moreover, the application in dye-sensitized solar cells was investigated, showing that the power conversion efficiency increases by the insertion of the phenyl unit.

  4. A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells.

    Science.gov (United States)

    Sorohhov, Gleb; Yi, Chenyi; Grätzel, Michael; Decurtins, Silvio; Liu, Shi-Xia

    2015-01-01

    Two new photosensitizers featured with a cyanoacrylic acid electron acceptor (A) and a hybrid electron donor (D) of cyclopentadithiophene and dithiafulvenyl, either directly linked or separated by a phenyl ring, were synthesized and characterized. Both of them undergo two reversible oxidations and strongly absorb in the visible spectral region due to a photo-induced intramolecular charge-transfer (ICT) transition. To a great extent, the electronic interaction between the D and A units is affected by the presence of a phenyl spacer. Without a phenyl ring, the D unit appears more difficult to oxidize due to a strong electron-withdrawing effect of the A moiety. In sharp contrast, the insertion of the phenyl ring between the D and A units leads to a broken π-conjugation and therefore, the oxidation potentials remain almost unchanged compared to those of an analogue without the A group, suggesting that the electronic coupling between D and A units is relatively weak. As a consequence, the lowest-energy absorption band shows a slight hypsochromic shift upon the addition of the phenyl spacer, indicative of an increased HOMO-LUMO gap. In turn, the direct linkage of D and A units leads to an effective π-conjugation, thus substantially lowering the HOMO-LUMO gap. Moreover, the application in dye-sensitized solar cells was investigated, showing that the power conversion efficiency increases by the insertion of the phenyl unit.

  5. Correcting for 3D distortion when using backscattered electron detectors in a scanning electron microscope.

    Science.gov (United States)

    Proctor, Jacob M

    2009-01-01

    A variable pressure scanning electron microscope (VPSEM) can produce a topographic surface relief of a physical object under examination, in addition to its two-dimensional (2D) image. This topographic surface relief is especially helpful when dealing with porous rock because it may elucidate the pore-space structure as well as grain shape and size. Whether the image accurately reproduces the physical object depends on the management of the hardware, acquisition, and postprocessing. Two problems become apparent during testing: (a) a topographic surface relief of a precision ball bearing is distorted and does not correspond to the physical dimensions of the actual sphere and (b) an image of a topographic surface relief of a Berea sandstone is geometrically tilted and topographically distorted even after standard corrections are applied. The procedure presented here is to ensure the veracity of the image, and includes: (a) adjusting the brightness and contrast levels originally provided by the manufacturer and (b) tuning the amplifiers of the backscatter detector plates to be equal to each other, and producing zero voltage when VPSEM is idle. This procedure is tested and verified on the said two physical samples. SCANNING 31: 59-64, 2009. (c) 2009 Wiley Periodicals, Inc.

  6. Comparative study of electron microscopy and scanning probe microscopy in photosynthetic research

    OpenAIRE

    MATĚNOVÁ, Martina

    2009-01-01

    The aim of this study is to compare the ability of transmission electron microscopy, scanning electron microscopy and atomic force microscopy to visualize individual protein complexes. The principle of electron microscopy and atomic force microscopy is explained. For comparision of these methods well characterized photosynthetic complexes LH1, LH2, PSI and PSII were selected.

  7. Local thermal conductivity of polycrystalline AlN ceramics measured by scanning thermal microscopy and complementary scanning electron microscopy techniques

    Institute of Scientific and Technical Information of China (English)

    Zhang Yue-Fei; Wang Li; R. Heiderhoff; A. K. Geinzer; Wei Bin; Ji Yuan; Han Xiao-Dong; L. J. Balk; Zhang Ze

    2012-01-01

    The local thermal conductivity of polycrystalline aluminum nitride (AlN) ceramics is measured and imaged by using a scanning thermal microscope (SThM) and complementary scanning electron microscope (SEM) based techniques at room temperature.The quantitative thermal conductivity for the AlN sample is gained by using a SThM with a spatial resolution of sub-micrometer scale through using the 3w method.A thermal conductivity of 308 W/m·K withingrains corresponding to that of high-purity single crystal AlN is obtained.The slight differences in thermal conduction between the adjacent grains are found to result from crystallographic misorientations,as demonstrated in the electron backscattered diffraction.A much lower thermal conductivity at the grain boundary is due to impurities and defects enriched in these sites,as indicated by energy dispersive X-ray spectroscopy.

  8. Improving Electron Transfer from Dye to TiO2 by Using CdTe Nanostructure Layers in Dye-Sensitized Solar Cells

    Science.gov (United States)

    Beshkar, Farshad; Sabet, Mohammad; Salavati-Niasari, Masoud

    2015-08-01

    In this work, TiO2 P25 was deposited successfully on the FTO glass by electrophoresis method. Different chemical methods were served for deposition of nanosized CdTe such as successive ion layer adsorption and reaction (SILAR) and drop-cast. Dye-sensitized solar cells were fabricated from prepared electrodes, Pt as a counter electrode, dye solution, and electrolyte. The effects of chemical deposition methods were investigated on the surface quality, optical properties, and solar cell efficiency. It was observed that deposition method has an important role on the solar cell performance. It was also seen that deposition method affects directly on surface thickness and the amount of dye adsorption. In fact, each deposition method creates different surfaces, and hence, they act variously in electron transfer across the electrode surface. Among different deposition methods that were used in this experimental work, SILAR method showed the best performance and the surface that was created by this method could transfer the electrons across the electrode faster than the other ones. But this chemical method cannot improve solar cell efficiency due to some different reasons that we mentioned in this paper.

  9. Surface sensitivity effects with local probe scanning Auger–scanning electron microscopy

    NARCIS (Netherlands)

    Agterveld, D.T.L. van; Palasantzas, G.; Hosson, J.Th.M. De

    1999-01-01

    This letter concentrates on a quantitative description of surface roughness effects on Auger peak-line profiles for pure and alloyed specimens. The nanometer lateral electron probe size of the order of 10 nm yielded peak-line profiles that capture surface topology variations down to nanometer-length

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

    Science.gov (United States)

    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.

  11. Effect of different photoanode nanostructures on the initial charge separation and electron injection process in dye sensitized solar cells: A photophysical study with indoline dyes

    Energy Technology Data Exchange (ETDEWEB)

    Idígoras, Jesús [Nanostructured Solar Cells Group, Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, Ctra. Utrera, km 1, ES-41013 Seville (Spain); Sobuś, Jan [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University in Poznań, Umultowska 85, 61-614 Poznań (Poland); Jancelewicz, Mariusz [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Azaceta, Eneko; Tena-Zaera, Ramon [Materials Division, IK4-CIDETEC, Parque Tecnológico de San Sebastián, Paseo Miramón 196, Donostia-San Sebastián, 20009 (Spain); Anta, Juan A. [Nanostructured Solar Cells Group, Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, Ctra. Utrera, km 1, ES-41013 Seville (Spain); Ziółek, Marcin, E-mail: marziol@amu.edu.pl [Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University in Poznań, Umultowska 85, 61-614 Poznań (Poland)

    2016-02-15

    Ultrafast and fast charge separation processes were investigated for complete cells based on several ZnO-based photoanode nanostructures and standard TiO{sub 2} nanoparticle layers sensitized with the indoline dye coded D358. Different ZnO morphologies (nanoparticles, nanowires, mesoporous), synthesis methods (hydrothermal, gas-phase, electrodeposition in aqueous media and ionic liquid media) and coatings (ZnO–ZnO core–shell, ZnO–TiO{sub 2} core–shell) were measured by transient absorption techniques in the time scale from 100 fs to 100 μs and in the visible and near-infrared spectral range. All of ZnO cells show worse electron injection yields with respect to those with standard TiO{sub 2} material. Lower refractive index of ZnO than that of TiO{sub 2} is suggested to be an additional factor, not considered so far, that can decrease the performance of ZnO-based solar cells. Evidence of the participation of the excited charge transfer state of the dye in the charge separation process is provided here. The lifetime of this state in fully working devices extends from several ps to several tens of ps, which is much longer than the typically postulated electron injection times in all-organic dye-sensitized solar cells. The results here provided, comprising a wide variety of morphologies and preparation methods, point to the universality of the poor performance of ZnO as photoanode material with respect to standard TiO{sub 2}. - Highlights: • Wide variety of morphologies and preparation methods has been checked for ZnO cells. • All ZnO cells work worse than TiO{sub 2} ones. • Effective refractive index might be an additional factor in solar cell performance. • Excited charge transfer state of indoline dyes participates in the charge separation.

  12. 3D correlative light and electron microscopy of cultured cells using serial blockface scanning electron microscopy

    Science.gov (United States)

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

    2017-01-01

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

  13. 3D correlative light and electron microscopy of cultured cells using serial blockface scanning electron microscopy.

    Science.gov (United States)

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

    2017-01-01

    The processes of life take place in multiple dimensions, but imaging these processes in even three dimensions is challenging. Here, we describe a workflow for 3D correlative light and electron microscopy (CLEM) of cell monolayers using fluorescence microscopy to identify and follow biological events, combined with serial blockface scanning electron microscopy to analyse the underlying ultrastructure. The workflow encompasses all steps from cell culture to sample processing, imaging strategy, and 3D image processing and analysis. We demonstrate successful application of the workflow to three studies, each aiming to better understand complex and dynamic biological processes, including bacterial and viral infections of cultured cells and formation of entotic cell-in-cell structures commonly observed in tumours. Our workflow revealed new insight into the replicative niche of Mycobacterium tuberculosis in primary human lymphatic endothelial cells, HIV-1 in human monocyte-derived macrophages, and the composition of the entotic vacuole. The broad application of this 3D CLEM technique will make it a useful addition to the correlative imaging toolbox for biomedical research. © 2017. Published by The Company of Biologists Ltd.

  14. Ultrastructure of Proechinophthirus zumpti (Anoplura, Echinophthiriidae by scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Dolores del Carmen Castro

    2002-09-01

    Full Text Available The ultrastructure of Proechinophthirus zumpti Werneck, 1955, mainly the external chorionic features of the egg, is described through electronic microscopy techniques. This species was first cited in Argentina, infesting Arctocephalus australis (Zimmermann, 1873. The morphological adaptations of adults and nymphs are described in both species of Proechinophthirus parasitic on Otariidae: P. fluctus (Ferris, 1916 and P. zumpti.

  15. Scanning-electron-microscope used in real-time study of friction and wear

    Science.gov (United States)

    Brainard, W. A.; Buckley, D. H.

    1975-01-01

    Small friction and wear apparatus built directly into scanning-electron-microscope provides both dynamic observation and microscopic view of wear process. Friction and wear tests conducted using this system have indicated that considerable information can readily be gained.

  16. Seasonal variation in an annually-banded coral Porites: A scanning electron microscopy investigation

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.A.S.

    Seasonal bands of the hard coral @iPorites@@ sp. collected from three different islands of Lakshadweep (Northwest Indian Ocean) are examined under a scanning electron microscope (SEM). SEM photographs reveal the presence of detrital inclusions...

  17. A Low Cost, Electronically Scanned Array (ESA) Antenna Technology for Aviation Hazard Detection and Avoidance Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed project will investigate the feasibility of utilizing ThinKom's low cost electronically scanned array (ESA) antenna concepts to enable affordable...

  18. Scanning electron microscopy of acrothoracican cypris larvae (Crustacea, Thecostraca, Cirripedia, Acrothoracica, Lithoglyptidae)

    NARCIS (Netherlands)

    Kolbasov, Gregory A.; Høeg, Jens T.; Elfimov, Alexei S.

    1999-01-01

    Scanning electron microscopy was used to provide a full morphological description of cypris morphology in the acrothoracican species Lithoglyptes milis and L. habei (Lithoglyptidae). Special attention was given to lattice organs, antennules, thorax, thoracopods, abdomen, and furcal rami. Cypris larv

  19. Manufacture and scanning electron microscopic observation of human dermis collagen membrane

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    @@ Introduction Collagen is a kind of biomacromolecule and can be used as cover material for burn wounds. In this article,we report the scanning electron microscopic observation of human dermis collagen membrane prepared by three methods.

  20. Quantitative detection of gold nanoparticles on individual, unstained cancer cells by scanning electron microscopy

    NARCIS (Netherlands)

    Hartsuiker, L.; Es, van P.; Petersen, W.; Leeuwen, van T.G.; Terstappen, L.W.M.M.; Otto, C.

    2011-01-01

    Gold nanoparticles are rapidly emerging for use in biomedical applications. Characterization of the interaction and delivery of nanoparticles to cells through microscopy is important. Scanning electron microscopes have the intrinsic resolution to visualize gold nanoparticles on cells. A novel sample

  1. Quantitative detection of gold nanoparticles on individual, unstained cancer cells by scanning electron microscopy.

    Science.gov (United States)

    Hartsuiker, L; VAN Es, P; Petersen, W; VAN Leeuwen, T G; Terstappen, L W M M; Otto, C

    2011-11-01

    Gold nanoparticles are rapidly emerging for use in biomedical applications. Characterization of the interaction and delivery of nanoparticles to cells through microscopy is important. Scanning electron microscopes have the intrinsic resolution to visualize gold nanoparticles on cells. A novel sample preparation protocol was developed to enable imaging of cells and gold nanoparticles with a conventional below lens scanning electron microscopes. The negative influence of 'charging' on the quality of scanning electron microscopes' images could be limited by deposition of biological cells on a conductive (gold) surface. The novel protocol enabled high-resolution scanning electron microscopes' imaging of small clusters and individual gold nanoparticles on uncoated cell surfaces. Gold nanoparticles could be counted on cancer cells with automated routines.

  2. Quantitative detection of gold nanoparticles on individual, unstained cancer cells by Scanning Electron Microscopy

    NARCIS (Netherlands)

    Hartsuiker, Liesbeth; van Es, Peter; Petersen, Wilhelmina; van Leeuwen, Ton; Terstappen, Leonardus Wendelinus Mathias Marie; Otto, Cornelis

    2011-01-01

    Gold nanoparticles are rapidly emerging for use in biomedical applications. Characterization of the interaction and delivery of nanoparticles to cells through microscopy is important. Scanning electron microscopes have the intrinsic resolution to visualize gold nanoparticles on cells. A novel sample

  3. Interstitial cells of Cajal and Auerbach's plexus. A scanning electron microscopical study of guinea-pig small intestine

    DEFF Research Database (Denmark)

    Jessen, Harry; Thuneberg, Lars

    1991-01-01

    Anatomy, interstitial cells of Cajal, myenteric plexus, small intestine, guinea-pig, scanning electron microscopy......Anatomy, interstitial cells of Cajal, myenteric plexus, small intestine, guinea-pig, scanning electron microscopy...

  4. Evaluation of the bleached human enamel by Scanning Electron Microscopy

    DEFF Research Database (Denmark)

    Miranda, Carolina Baptista; Pagani, Clovis; Benetti, Ana Raquel

    2005-01-01

    Since bleaching has become a popular procedure, the effect of peroxides on dental hard tissues is of great interest in research. Purpose: The aim of this in vitro study was to perform a qualitative analysis of the human enamel after the application of in-office bleaching agents, using Scanning......: 2h); G3- four 2-hour exposures to 35% carbamide peroxide (total exposure: 8h); G4- two applications of 35% hydrogen peroxide, which was light-activated with halogen lamp at 700mW/cm² during 7min and remained in contact with enamel for 20min (total exposure: 40min). All bleaching treatments adopted...... analysis performing gold sputter coating under vacuum and were examined using 15kV at 500x and 2000x magnification. Results: Morphological alterations on the enamel surface were similarly detected after bleaching with either 35% carbamide peroxide or 35% hydrogen peroxide. Surface porosities were...

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

    Energy Technology Data Exchange (ETDEWEB)

    Zaka, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  8. Correlative Analysis of Immunoreactivity in Confocal Laser-Scanning Microscopy and Scanning Electron Microscopy with Focused Ion Beam Milling

    Directory of Open Access Journals (Sweden)

    Takahiro eSonomura

    2013-02-01

    Full Text Available Three-dimensional reconstruction of ultrastructure of rat brain with minimal effort has recently been realized by scanning electron microscopy combined with focused ion beam milling (FIB-SEM. Because application of immunohistochemical staining to electron microscopy has a great advantage in that molecules of interest are specifically localized in ultrastructures, we here tried to apply immunocytochemistry to FIB-SEM and correlate immunoreactivity in confocal laser-scanning microcopy (CF-LSM with that in FIB-SEM. The dendrites of medium-sized spiny neurons in rat neostriatum were visualized with a recombinant viral vector, which labeled the infected neurons with membrane-targeted GFP in a Golgi stain-like fashion, and thalamostriatal afferent terminals were immunolabeled with Cy5 fluorescence for vesicular glutamate transporter 2 (VGluT2. After detecting the sites of terminals apposed to the dendrites in CF-LSM, GFP and VGluT2 immunoreactivities were further developed for electron microscopy by the immunogold/silver enhancement and immunoperoxidase/diaminobenzidine (DAB methods, respectively. In the contrast-inverted FIB-SEM images, silver precipitation and DAB deposits were observed as fine dark grains and diffuse dense profiles, respectively, indicating that these immunoreactivities were easily recognizable as in the images of transmission electron microscopy. In the sites of interest, some appositions were revealed to display synaptic specialization of asymmetric type. The present method is thus useful in the three-dimensional analysis of immunocytochemically differentiated synaptic connection in the central neural circuit.

  9. Probing Nanoscale Electronic and Magnetic Interaction with Scanning Tunneling Spectroscopy

    DEFF Research Database (Denmark)

    Bork, Jakob

    coverage the silver preferably nucleates on top of the bilayer high cobalt islands compared to directly on the Cu(111) substrate. Furthermore, the silver forms a combination of a reconstruction and a Moire pattern which is investigated with low-energy electron diraction and spectroscopic STM mapping at 6....... The heterostructure is found to have very interesting electronic properties. The d-related state from the now buried cobalt island is visible through the silver capping layer, but the silver Moire pattern modulates the spin-polarized cobalt d-related state in amplitude, energy position and width. This is related......, but the Fano line ii shape changes continuously from a dip to a peak. In the antiferromagnetic regime, inelastic spin-ip excitations reveal a splitting with a continuous increase in energy levels when pushing the atoms further together. This is supported by numerical renormalization group calculations...

  10. Traceability of Dimensional Measurements using the Scanning Electron Microscope

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo; Bariani, Paolo; Hansen, Hans Nørgaard

    2004-01-01

    its unique combination of three imaging properties: • Lateral ultimate resolution down to 2 nm • Large range of possible magnification levels ranging from a few hundred times to hundred thousand times magnification • Large depth of field Topography reconstruction with this instrument and photogra...... investigation is presented that addresses the performance of 3D topography calculation based on secondary electron imaging and the stereo-pair technique....

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

    Energy Technology Data Exchange (ETDEWEB)

    Keutner, Christoph [Technische Univ. Dortmund, Dortmung (Germany); von Bohlen, Alex [Leibniz-Institut fur Analytische Wissenschaften, Dortmund (Germany); Berges, Ulf [Technische Univ. Dortmund, Dortmung (Germany); Espeter, Philipp [Technische Univ. Dortmund, Dortmung (Germany); Schneider, Claus M. [Peter Grunberg Institut, Julich (Germany); Westphal, Carsten [Technische Univ. Dortmund, Dortmung (Germany)

    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.

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

    Science.gov (United States)

    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

  13. N-Annulated perylene substituted zinc–porphyrins with different linking modes and electron acceptors for dye sensitized solar cells

    KAUST Repository

    Luo, Jie

    2016-05-03

    Three new N-annulated perylene (NP) substituted porphyrin dyes WW-7-WW-9 with different linking modes and accepting groups were synthesized and applied in Co(ii)/(iii) based dye sensitized solar cells (DSCs). The bay-linked porphyrins WW-7 and WW-8 exhibited moderate power conversion efficiency (PCE = 4.4% and 4.8%, respectively), while the peri-linked porphyrin dye WW-9 showed a PCE up to 9.2% which is slightly lower than that of our reference dye WW-6. Detailed physical measurements (optical and electrochemical), DFT calculations, and photovoltaic characterizations were performed to understand how the structural changes affect their light-harvesting ability, molecular orbital profile, energy level alignment, and eventually the photovoltaic performance. It turned out that the lower efficiencies of the cells based on WW-7 and WW-8 could be ascribed to the weak π-conjugation between the bay-substituted NP and phenylethynyl substituted porphyrin unit. The introduction of a benzothiadiazole acceptor at the anchoring group has induced a significant red shift of the IPCE action spectra of WW-8 and WW-9, by about 90 nm and 50 nm as compared to that of WW-7 and WW-6, respectively. However, less efficient electron injection was observed. Our studies gave some insight into the important role of electronic interactions between different components when one designs a dye for high-efficiency DSCs. © The Royal Society of Chemistry 2016.

  14. The Influence of Cationization on the Dyeing Performance of Cotton Fabrics with Direct Dyes

    Directory of Open Access Journals (Sweden)

    M. F. Shahin

    2015-08-01

    Full Text Available The effect of cationic modification of cotton fabrics, using cationic agent (Chromatech 9414 on direct dyeing characteristics was studied in this work. Cationization of cotton fabric at different conditions (pH, cationic agent concentration, temperature and time was investigated and the optimum conditions were determined . Nitrogen content of cotton samples pretreated with cationic agent was indicated. The results showed that increasing cationic agent concentration lead to higher nitrogen content on cotton fabric . The cationized cotton fabrics were dyed with two direct dyes (C.I. Direct Yellow 142 - C.I. Direct red 224 and the results were compared to untreated cotton fabrics. The parameters which may affect the dyeing process such as dye concn., addition of salt, time and temperature of dyeing were studied. The dyeing results illustrate that cationization improves the fabric dyeability compared to the uncationized cotton and the magnitude of increase in colour depth depends on the nitrogen content of the cationized cotton fabric .The results also refer to possibility of dyeing cationized cotton fabric with direct dyes without addition of electrolytes to give colour strength higher than that achieved on uncationized cotton using conventional dyeing method .Another important advantage of cationic treatment is in the saving of dye concn., energy ,dyeing time , rinse water and subsequently saving of waste water treatment , and finally minimizes the environmental pollution . The changes in surface morphology of fibres after cationization were identified by various methods such as wettability and scanning with the electron microscope. Different fastness properties were evaluated.

  15. Deciphering effects of functional groups and electron density on azo dyes degradation by graphene loaded TiO2

    Science.gov (United States)

    Zhang, Qian; Liang, Xiao; Chen, Bor-Yann; Chang, Chang-Tang

    2015-12-01

    This study tended to decipher the mechanism of photo degradation of azo dyes, which bond was favorable to be broken for application of wastewater decolorization. That is, from chemical structure perspective, the critical substituents to affect electron donor/acceptor for dye degradation would be identified in this research. The model reactive blacks (RB5), reactive blue 171 (RB171) and reactive red 198 (RR198) were degraded by graphene loaded TiO2, indicating how the electron withdrawing and releasing groups affect azo dye degradability. The byproducts and intermediate products were analyzed by ultraviolet-visible spectroscopy (UV-vis), gas chromatography-mass spectrometry (GC-MS) and ion chromatography (IC). Furthermore, the radicals involved in the reaction were found by electron paramagnetic resonance (ESR) to confirm the main oxidized species of hydroxyl radicals rather than the light generated positive holes. The finding revealed that the breakages of the bonds were due to the electron density changes around the bonds. This principle can be applicable not only for RB5 degradation, but also for reactive blue 171 (RB171), reactive red 198 (RR198) and some other textile dyes.

  16. Development of a fast electromagnetic shutter for compressive sensing imaging in scanning transmission electron microscopy

    CERN Document Server

    Béché, Armand; Freitag, Bert; Verbeeck, Jo

    2015-01-01

    The concept of compressive sensing was recently proposed to significantly reduce the electron dose in scanning transmission electron microscopy (STEM) while still maintaining the main features in the image. Here, an experimental setup based on an electromagnetic shutter placed in the condenser plane of a STEM is proposed. The shutter blanks the beam following a random pattern while the scanning coils are moving the beam in the usual scan pattern. Experimental images at both medium scale and high resolution are acquired and then reconstructed based on a discrete cosine algorithm. The obtained results confirm the predicted usefulness of compressive sensing in experimental STEM even though some remaining artifacts need to be resolved.

  17. Boundary scan test of Belle II pixel detector electronics

    Energy Technology Data Exchange (ETDEWEB)

    Leitl, Philipp [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, 80805 Muenchen (Germany)

    2015-07-01

    For the upgrade of the Vertex Detector at the Belle II experiment, DEPFET sensors will be used. These sensors need Application-Specific Integrated Circuits (ASICs) for control, readout and data processing. Because of high demands for a low material budget in the sensitive area, there is only little space left for these ASICs. Using state-of-the-art technologies like Ball Grid Array (BGA) chips, which are flip-chip mounted, the requirement of 14 ASICs on each of the 40 half ladders can be fulfilled. However, this highly integrated on-sensor ASIC solution results in a lack of physical access to the electrical connections, which is a problem for traditional testing methods. To overcome these limitations, the JTAG standard IEEE 1149.1 is used to check if the circuit is in working condition. This method provides electrical access to the boundary scan cells implemented in the ASICs. Therefore it is possible to perform connectivity tests and verify if the production of the circuit was successful.

  18. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  1. Some strategies for quantitative scanning Auger electron microscopy

    Science.gov (United States)

    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.

  2. Some strategies for quantitative scanning Auger electron microscopy

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zaka, Fowzia [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Energetic Materials Center

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zaka, Fowzia [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Energetic Materials Center

    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.

  6. Nano-tomography of porous geological materials using focused ion beam-scanning electron microscopy

    NARCIS (Netherlands)

    Liu, Yang; King, Helen E.; van Huis, Marijn A.; Drury, Martyn R.; Plümper, Oliver

    2016-01-01

    Tomographic analysis using focused ion beam-scanning electron microscopy (FIB-SEM) provides three-dimensional information about solid materials with a resolution of a few nanometres and thus bridges the gap between X-ray and transmission electron microscopic tomography techniques. This contribution

  7. Glass for parenteral products: a surface view using the scanning electron microscope.

    Science.gov (United States)

    Roseman, T J; Brown, J A; Scothorn, W W

    1976-01-01

    The scanning electron microscope was utilized to explore the internal surface of glass ampuls and vials used in parenteral products. The surface topography of USP Type I borosilicate glass containers was viewed after exposure to "sulfur," ammonium bifluoride, and sulfuric acid treatments. The scanning electron micrographs showed startling differences in the appearance of the surface regions. "Sulfur treatment" of ampuls was associated with a pitting of the surface and the presence of sodium sulfate crystals. The sulfur treatment of vials altered the glass surface in a characteristically different manner. The dissimilarity between the surface appearances was attributed to the method of sulfur treatment. Ampuls exposed to sulfuric acid solutions at room temperature did not show the pitting associated with the sulfur treatment. Scanning electron micrographs of ammonium bifluoride-treated ampuls showed a relief effect, suggesting that the glass was affected by the bifluoride solution but that sufficient stripping of the surface layer did not occur to remove the pits associated with the sulfur treatment. Flakes emanating from the glass were identified with the aid of the electron microprobe. Scanning electron micrographs showed that these vitreous flakes resulted from a delamination of a thin layer of the glass surface. It is concluded that the scanning electron microscope, in conjunction with other analytical techniques, is a valuable tool in assessing the quality of glass used for parenteral products. The techniques studied should be of particular importance to the pharmaceutical industry where efforts are being made to reduce the levels of particulate matter in parenteral dosage forms.

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

    Science.gov (United States)

    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.

  9. Electron transfer dynamics of triphenylamine dyes bound to TiO2 nanoparticles from femtosecond stimulated Raman spectroscopy

    KAUST Repository

    Hoffman, David P.

    2013-04-11

    Interfacial electron transfer between sensitizers and semiconducting nanoparticles is a crucial yet poorly understood process. To address this problem, we have used transient absorption (TA) and femtosecond stimulated Raman spectroscopy (FSRS) to investigate the photoexcited dynamics of a series of triphenylamine-coumarin dye/TiO2 conjugates. The TA decay is multiexponential, spanning time scales from 100 fs to 100 ps, while the characteristic transient Raman spectrum of the radical cation decays biexponentially with a dominant ∼3 ps component. To explain these observations, we propose a model in which the decay of the TA is due to hot electrons migrating from surface trap states to the conduction band of TiO 2 while the decay of the Raman signature is due to internal conversion of the dye molecule. Furthermore, the S1 Raman spectrum of TPAC3, a dye wherein a vinyl group separates the triphenylamine and coumarin moieties, is similar to the S1 Raman spectrum of trans-stilbene; we conclude that their S1 potential energy surfaces and reactivity are also similar. This correlation suggests that dyes containing vinyl linkers undergo photoisomerization that competes with electron injection. © 2013 American Chemical Society.

  10. Sub-micron imaging of buried integrated circuit structures using scanning confocal electron microscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Frigo, S. P.; Levine, Z.; Zaluzec, N. J.; Materials Science Division; Northern Arizona Univ.; NIST

    2002-09-09

    Two-dimensional images of model integrated circuit components were collected using the technique of scanning confocal electron microscopy. For structures embedded about 5 {mu}m below the surface of a silicon oxide dielectric, a lateral resolution of 76{+-}9 nm was measured. Elemental mapping via x-ray emission spectrometry is demonstrated. A parallax analysis of images taken for various tilt angles to the electron beam allowed determination of the spacing between two wiring planes. The results show that scanning confocal electron microscopy is capable of probing buried structures at resolutions that will be necessary for the inspection of next-generation integrated circuit technology.

  11. Scanning and Transmission Electron Microscopy of High Temperature Materials

    Science.gov (United States)

    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.

  12. Thermal Properties of Materials Characterized by Scanning Electron-Acoustic Microscopy

    Institute of Scientific and Technical Information of China (English)

    GAO Chun-Ming; ZHANG Shu-Yi; ZHANG Zhong-Ning; SHUI Xiu-Ji; JIANG Tao

    2005-01-01

    @@ A modified technique of scanning electron-acoustic microscopy is employed to determine thermal diffusivity of materials. Using the dependence of the electron-acoustic signal on modulation frequency of the electron beam,the thermal diffusivity of materials is characterized based on a simplified thermoelastic theory. The thermal diffusivities of several metals characterized by the modified scanning electron-acoustic microscopy are in good agreement with the referential values of the corresponding materials, which proves that the scanning electronacoustic microscopy can be used to characterize the thermal diffusivity of materials effectively. In addition, for micro-inhomogeneous materials, such as biological tissues, the macro-effective (average) thermal diffusivities are characterized by the technique.

  13. Fine structure of the endolymphatic duct in the rat. A scanning and transmission electron microscopy study

    DEFF Research Database (Denmark)

    Qvortrup, K; Rostgaard, Jørgen; Bretlau, P

    1995-01-01

    To investigate the surface morphology of the endolymphatic duct epithelium, 8 rats were vascularly perfused with glutaraldehyde in a buffered and oxygenated blood substitute. Optimal preservation of the epithelium for scanning electron microscopy was attained by coating of the specimens with OsO4...... and thiocarbohydrazide followed by a continuous dehydration procedure. Three types of cells were identified with the scanning electron microscope: A polygonal and oblong epithelial cell was observed in the largest number throughout the duct, whereas in the juxta-saccular half of the duct two additional types...... of epithelial cells were observed. The scanning electron microscopical observations are compared and discussed with reference to transmission electron microscopical observations of the endolymphatic duct....

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

    Science.gov (United States)

    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.

  15. A Rationally Designed, General Strategy for Membrane Orientation of Photoinduced Electron Transfer-Based Voltage-Sensitive Dyes.

    Science.gov (United States)

    Kulkarni, Rishikesh U; Yin, Hang; Pourmandi, Narges; James, Feroz; Adil, Maroof M; Schaffer, David V; Wang, Yi; Miller, Evan W

    2017-02-17

    Voltage imaging with fluorescent dyes offers promise for interrogating the complex roles of membrane potential in coordinating the activity of neurons in the brain. Yet, low sensitivity often limits the broad applicability of optical voltage indicators. In this paper, we use molecular dynamics (MD) simulations to guide the design of new, ultrasensitive fluorescent voltage indicators that use photoinduced electron transfer (PeT) as a voltage-sensing switch. MD simulations predict an approximately 16% increase in voltage sensitivity resulting purely from improved alignment of dye with the membrane. We confirm this theoretical finding by synthesizing 9 new voltage-sensitive (VoltageFluor, or VF) dyes and establishing that all of them display the expected improvement of approximately 19%. This synergistic outworking of theory and experiment enabled computational and theoretical estimation of VF dye orientation in lipid bilayers and has yielded the most sensitive PeT-based VF dye to date. We use this new voltage indicator to monitor voltage spikes in neurons from rat hippocampus and human pluripotent-stem-cell-derived dopaminergic neurons.

  16. Radiation chemistry of cyanine dyes: Oxidation and reduction of merocyanine 540. [Accelerated electrons

    Energy Technology Data Exchange (ETDEWEB)

    Harriman, A. (Univ. of Texas, Austin (United States)); Shoute, L.C.T.; Neta, P. (National Inst. of Standards and Technology, Gaithersburg, MD (United States))

    1991-03-21

    Merocyanine 540 (MC) shows promise as a treatment for certain types of leukemia. It is shown that MC readily undergoes one-electron reduction under pulse radiolytic conditions. The {pi}-radical anion, produced by reduction with hydrated electrons and 2-hydroxypropyl radicals, disproportionates rapidly (k = 1.9 {times} 10{sup 9} M{sup {minus}1}s{sup {minus}1}) under anaerobic conditions but reduces O{sub 2} to superoxide ions (k = 1.6 {times} 10{sup 9} M{sup {minus}1}s{sup {minus}1}) in aerated solution. The dye reacts with trichloromethylperoxyl radicals (k = 9 {times} 10{sup 8} M{sup {minus}1}s{sup {minus}1}) to form several products, one of which is believed to be an adduct formed by addition of CCl{sub 3}OO{sup {sm bullet}} to the bridgehead carbon atom of the benzoxazole subunit. This species decays via first-order kinetics (k = 4.0 {times} 10{sup 3} s{sup {minus}1}) under pulse radiolytic conditions to form cleavage products. A second primary product is believed to arise from addition of CCl{sub 3}O{sub 2}{sup {sm bullet}} to the polymethine chain to form an {alpha}-amino carbon-centered radical capable of reducing O{sub 2} to superoxide ions. Preliminary studies indicate that the breakdown products are cytotoxic and could be important intermediates for the known antiviral activity of MC.

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

    Science.gov (United States)

    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.

  18. Revealing the 1 nm/s Extensibility of Nanoscale Amorphous Carbon in a Scanning Electron Microscope

    DEFF Research Database (Denmark)

    Zhang, Wei

    2013-01-01

    In an ultra-high vacuum scanning electron microscope, the edged branches of amorphous carbon film (∼10 nm thickness) can be continuously extended with an eye-identifying speed (on the order of ∼1 nm/s) under electron beam. Such unusual mobility of amorphous carbon may be associated with deformation...... promoted by the electric field, which resulted from an inner secondary electron potential difference from the main trunk of carbon film to the tip end of branches under electron beam. This result demonstrates importance of applying electrical effects to modify properties of carbon materials. It may have...... positive implications to explore some amorphous carbon as electron field emission device. SCANNING 35: 261-264, 2013. © 2012 Wiley Periodicals, Inc....

  19. Examination of mycological samples by means of the scanning electron microscope

    Directory of Open Access Journals (Sweden)

    M. Thibaut

    1973-04-01

    Full Text Available Three species of Siphomycetes: Rhizopus arhizus, Rhizopus equinus and Rhizopus nigricans, as well as a Septomycete: Emericella nidulans, have been examined by means of a scanning electron microscope. Among the difjerent Rhizopus, this technique showed differences in the appearance of the sporangia. In Emericella nidulans, scanning microscopy enábled one to ascertain that the "Hull cells" were completely hollow and also demonstrated the ornemented aspect of the ascospores.

  20. Surface morphology of the endolymphatic duct in the rat. A scanning electron microscopy study

    DEFF Research Database (Denmark)

    Qvortrup, K; Rostgaard, Jørgen; Bretlau, P

    1995-01-01

    Following intracardiac vascular perfusion fixation of 8 rats with glutaraldehyde in a buffered and oxygenated blood substitute, the vestibular aqueduct and endolymphatic duct were opened by microsurgery of the resulting 16 temporal bones. Optimum preservation of the epithelium for scanning electron...... were identified with the scanning electron microscope. A polygonal and oblong epithelial cell was observed in the largest number throughout the duct, and in the juxtasaccular half of the duct, two additional types of epithelial cells were observed. The scanning electron microscopic observations...... microscopy was attained by coating of the specimens with osmium tetroxide and thiocarbohydrazide followed by a continuous dehydration procedure. This technique permitted, for the first time, an investigation of the surface morphology of the epithelial cells in the endolymphatic duct. Three types of cells...

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

    Science.gov (United States)

    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.

  2. Electron transport and recombination in dye-sensitized solar cells made from single-crystal rutile TiO2 nanowires.

    Science.gov (United States)

    Enache-Pommer, Emil; Liu, Bin; Aydil, Eray S

    2009-11-14

    Contrary to expectations, the electron transport rate in dye-sensitized solar cells made from single-crystal rutile titanium dioxide nanowires is found to be similar to that measured in dye-sensitized solar cells made from titanium dioxide nanoparticles.

  3. Deciphering effects of functional groups and electron density on azo dyes degradation by graphene loaded TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qian [College of Chemical Engineering, HuaQiao University, Xiamen 361021 (China); Liang, Xiao [School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093 (China); Chen, Bor-Yann [Department of Chemical and Materials Engineering, National I-Lan University, 26047, Taiwan (China); Chang, Chang-Tang, E-mail: ctchang@niu.edu.tw [Department of Environmental Engineering, National I-Lan University, 26047, Taiwan (China)

    2015-12-01

    Highlights: • The degradation pathways of RB5, RB171 and RR198 have been identified. • The favorable bond to be broken under photo degradation was deciphered in this research. • The breakages of the bonds were due to the electron density changes around the bonds. • The hydroxyl radicals as the main oxidized species were confirmed by positive hole trapper and ESR. - Abstract: This study tended to decipher the mechanism of photo degradation of azo dyes, which bond was favorable to be broken for application of wastewater decolorization. That is, from chemical structure perspective, the critical substituents to affect electron donor/acceptor for dye degradation would be identified in this research. The model reactive blacks (RB5), reactive blue 171 (RB171) and reactive red 198 (RR198) were degraded by graphene loaded TiO{sub 2}, indicating how the electron withdrawing and releasing groups affect azo dye degradability. The byproducts and intermediate products were analyzed by ultraviolet–visible spectroscopy (UV–vis), gas chromatography–mass spectrometry (GC–MS) and ion chromatography (IC). Furthermore, the radicals involved in the reaction were found by electron paramagnetic resonance (ESR) to confirm the main oxidized species of hydroxyl radicals rather than the light generated positive holes. The finding revealed that the breakages of the bonds were due to the electron density changes around the bonds. This principle can be applicable not only for RB5 degradation, but also for reactive blue 171 (RB171), reactive red 198 (RR198) and some other textile dyes.

  4. Push–pull effect on the geometries, electronic and optical properties of thiophene based dye-sensitized solar cell materials

    Directory of Open Access Journals (Sweden)

    Ahmad Irfan

    2014-12-01

    Full Text Available Geometries, electronic structure and electronic absorption spectra of thiophene based dye-sensitized solar cells were performed using Density Functional Theory (DFT and time dependent density functional theory (TD-DFT. Different electron donating and electron withdrawing groups have been substituted. Geometries and electronic properties have been computed at B3LYP/6-31G∗∗ and absorption spectra at TD-B3LYP/6-31G∗∗ level of theory. Major change in bond lengths and bond angles occurs in the system where there is electron withdrawing or electron donating groups have been substituted. In SYSTEM-2 and SYSTEM-3 intra charge transfer has been observed. HOMO of SYSTEM-2 and SYSTEM-3 is delocalized on left side while LUMO on right side of the molecule. In SYSTEM-1, HOMO is on left side while LUMO is in the center. The designed systems show two absorption peaks for each of the system. In short, choice of appropriate electron withdrawing and donating groups is very important for improving the performance of dye-sensitized solar cells.

  5. Micrometer-sized fluorine doped tin oxide as fast electron collector for enhanced dye-sensitized solar cells.

    Science.gov (United States)

    Cui, Xiao Rui; Wang, Ye Feng; Li, Zhao; Zhou, Lu; Gao, Fei; Zeng, Jing Hui

    2014-10-08

    Titanium dioxide (TiO2)-layered fluorine doped tin oxide (FTO) powder was synthesized and applied as the photoanode in dye-sensitized solar cells (DSSCs). FTO powders are connected to form a direct electron pathway for the efficient extract of injected electrons, while the TiO2 layer serves as an energy barrier prohibiting the charge combination with oxidized dye or I3(-). The electrochemical impedance spectroscopy (EIS) analyses suggest that electrons have a longer combination lifetime (τe = 233 ms) than that of the electron in the DSSCs using traditional P25 photoanodes (τe = 28 ms). The DSSCs using 5 μm thick TiO2@FTO as photoanodes eventually give a respectable and long-term stable photovoltaic performance with a current density of 23.8 mA/cm(2), an open circuit voltage of 0.69 V, and power conversion efficiency of 7.4%. The results are received on a low dye loading level (0.25 × 10(-7) mol/cm(2)), which is (1)/10 of that for traditional photoanode (2.79 × 10(-7) mol/cm(2)).

  6. On the nature of excited electronic states in cyanine dyes: implications for visual pigment spectra

    Science.gov (United States)

    Dinur, Uri; Honig, Barry; Schulten, Klaus

    1980-06-01

    CNDO/S CI calculations are carried out on polyenes and on cyanine dyes. In contrast to polyenes, doubly excited configurations have a strong effect on the first optically allowed excited state in cyanines. Protonated Schiff bases of retinal are closely related to cyanine dyes, with important consequences for models of visual pigment spectra and photochemistry.

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

    Science.gov (United States)

    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).

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  10. Engineered core-shell nanofibers for electron transport study in dye-sensitized solar cells

    Science.gov (United States)

    Shabdan, Y.; Ronasi, A.; Coulibaly, P.; Moniruddin, M.; Nuraje, N.

    2017-06-01

    In this study, a unique approach was developed to synthesize 1-D core-shell nanofibers of carbon nanotubes (CNTs) and TiO2 using combination of coaxial electrospinning and sol-gel technique. Diameters of the fabricated core-shell single wall carbon nanotube-TiO2 (SWCNT-TiO2) and multi wall carbon nanotube-TiO2 (MWCNT-TiO2) nano-composite fibers were between 50-100nm. Energy dispersive spectroscopy (EDS) and X-ray photon spectroscopy (XPS) were applied to confirm encapsulation of carbon nanotube (CNT) in the core-shell structure. Electron transport properties of both SWCNT-TiO2 and MWCNT-TiO2 in the Dye-sensitized solar cells (DSSCs) were studied for the first time. It was found that SWCNT-TiO2 based DSSC provided higher short circuit current relative to MWCNT-TiO2, which was explained by I-V and bode plots. These findings were further illustrated by semi-conductive properties of SWCNT.

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

    Science.gov (United States)

    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.

  12. Unravelling the structural-electronic impact of arylamine electron-donating antennas on the performances of efficient ruthenium sensitizers for dye-sensitized solar cells

    Science.gov (United States)

    Chen, Wang-Chao; Kong, Fan-Tai; Ghadari, Rahim; Li, Zhao-Qian; Guo, Fu-Ling; Liu, Xue-Peng; Huang, Yang; Yu, Ting; Hayat, Tasawar; Dai, Song-Yuan

    2017-04-01

    We report a systematic research to understand the structural-electronic impact of the arylamine electron-donating antennas on the performances of the ruthenium complexes for dye-sensitized solar cells. Three ruthenium complexes functionalized with different arylamine electron-donating antennas (N,N-diethyl-aniline in RC-31, julolidine in RC-32 and N,N-dibenzyl-aniline in RC-36) are designed and synthesized. The photoelectric properties of RC dyes exhibit apparent discrepancy, which are ascribed to different structural nature and electronic delocalization ability of these arylamine electron-donating system. In conjunction with TiO2 microspheres photoanode and a typical coadsorbent DPA, the devices sensitized by RC-36 achieve the best conversion efficiency of 10.23%. The UV-Vis absorption, electrochemical measurement, incident photon-to-current conversion efficiency and transient absorption spectra confirm that the excellent performance of RC-36 is induced by synergistically structural-electronic impacts from enhanced absorption capacity and well-tuned electronic characteristics. These observations provide valuable insights into the molecular engineering methodology based on fine tuning structural-electronic impact of electron-donating antenna in efficient ruthenium sensitizers.

  13. Toxicity of imine-iminium dyes and pigments: electron transfer, radicals, oxidative stress and other physiological effects.

    Science.gov (United States)

    Kovacic, Peter; Somanathan, Ratnasamy

    2014-08-01

    Although conjugation is well known as an important contributor to color, there is scant recognition concerning involvement of imine and iminium functions in the physiological effects of this class of dyes and pigments. The group includes the dyes methylene blue, rhodamine, malachite green, fuchsin, crystal violet, auramine and cyanins, in addition to the pigments consisting of pyocyanine, phthalocyanine and pheophytin. The physiological effects consist of both toxicity and beneficial aspects. The unifying theme of electron transfer-reactive oxygen species-oxidative stress is used as the rationale in both cases. Toxicity is frequently prevented or alleviated by antioxidants. The apparent dichotomy of methylene blue action as both oxidant and antioxidant is rationalized based on similar previous cases. This mechanistic approach may have practical benefit. This review is important in conveying, for the first time, a unifying mechanism for toxicity based on electron transfer-reactive oxygen species-oxidative stress arising from imine-iminium.

  14. Cationic dye-sensitized degradation of sodium hyaluronate through photoinduced electron transfer in the upper excited state.

    Science.gov (United States)

    Kojima, M; Takahashi, K; Nakamura, K

    2001-09-01

    The formation of ground-state complexes of methylene blue (MB) and thionine (TN) with sodium hyaluronate (NaHA) was clearly observed by means of absorption spectra in aqueous solution. Irradiation of the complexes using 313 nm light caused significant degradation of NaHA under oxygen and argon. However, the use of visible light over 400 nm, which gives the lowest excited singlet state of the cationic dyes, caused no degradation. MB and TN were more efficient sensitizers for the degradation of NaHA than rose bengal (RB), although RB is a more efficient singlet oxygen (1O2) sensitizer than the cationic dyes. Under similar conditions the polysaccharides with carboxyl groups, such as alginic acid and polygalacturonic acid, also photodecomposed. However, the polysaccharides without carboxyl groups, such as pullulan and methyl cellulose, did not. The irradiation of the polysaccharides in the presence of powdered titanium dioxide as a photocatalyst to generate the hydroxyl radical (.OH) in aerated aqueous solution caused the fragmentation of all the polymers. It was confirmed that methyl viologen, an electron-accepting sensitizer, formed a charge-transfer complex with NaHA, the irradiation of which caused the efficient degradation of NaHA. In the presence of beta- and gamma-cyclodextrins the MB- and TN-sensitized photodegradation of NaHA was markedly suppressed. This was probably due to the formation of the inclusion complexes comprising the cationic dyes and the cyclodextrins. On the basis of the results obtained we propose that the cationic dye-sensitized degradation of NaHA involves a photoinduced electron-transfer process between the upper excited dyes and the ground-state NaHA and that .OH and 1O2 do not participate in the degradation.

  15. A scanning Auger electron spectrometer for internal surface analysis of Large Electron Positron 2 superconducting radio-frequency cavities

    Energy Technology Data Exchange (ETDEWEB)

    Benvenuti, C.; Cosso, R.; Genest, J.; Hauer, M.; Lacarrere, D.; Rijllart, A.; Saban, R. [CERN, 1211 Geneva 23 (Switzerland)

    1996-08-01

    A computer-controlled surface analysis instrument, incorporating static Auger electron spectroscopy, scanning Auger mapping, and secondary electron imaging, has been designed and built at CERN to study and characterize the inner surface of superconducting radio-frequency cavities to be installed in the Large Electron Positron collider. A detailed description of the instrument, including the analytical head, the control system, and the vacuum system is presented. Some recent results obtained from the cavities provide examples of the instrument{close_quote}s capabilities. {copyright} {ital 1996 American Institute of Physics.}

  16. Morphology and deflection properties of bat wing sensory hairs: scanning electron microscopy, laser scanning vibrometry, and mechanics model.

    Science.gov (United States)

    Sterbing-D'Angelo, S J; Liu, H; Yu, M; Moss, C F

    2016-08-22

    Bat wings are highly adaptive airfoils that enable demanding flight maneuvers, which are performed with astonishing robustness under turbulent conditions, and stability at slow flight velocities. The bat wing is sparsely covered with microscopically small, sensory hairs that are associated with tactile receptors. In a previous study we demonstrated that bat wing hairs are involved in sensing airflow for improved flight maneuverability. Here, we report physical measurements of these hairs and their distribution on the wing surface of the big brown bat, Eptesicus fuscus, based on scanning electron microscopy analyses. The wing hairs are strongly tapered, and are found on both the dorsal and ventral wing surfaces. Laser scanning vibrometry tests of 43 hairs from twelve locations across the wing of the big brown bat revealed that their natural frequencies inversely correlate with length and range from 3.7 to 84.5 kHz. Young's modulus of the average wing hair was calculated at 4.4 GPa, which is comparable with rat whiskers or arthropod airflow-sensing hairs.

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

    Energy Technology Data Exchange (ETDEWEB)

    Tong Yongpeng [Institute of Nuclear Techniques, Shenzhen University, Nanhai Avenue 3688, Shenzhen 518060 (China)], E-mail: yongpengt@yahoo.com.cn; Li Changming [School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637457 (Singapore); Liang Feng [Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200025 (China); Chen Jianmin [Shenzhen Municipal Hospital for Chronic Disease Control and Prevention, Guangdong 518020 (China); Zhang Hong; Liu Guoqing; Sun Huibin [Institute of Nuclear Techniques, Shenzhen University, Nanhai Avenue 3688, Shenzhen 518060 (China); Luong, John H.T. [Biotechnology Research Institute, National Research Council Canada, Montreal, Quebec, H4P 2R2 (Canada)

    2008-12-15

    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{sub 2}O{sub 3} and TiO{sub 2}) on a T lymphoblastic leukemia Jurkat cell line. The increased calcium ion (from CaCl{sub 2}) in the culture medium stimulated the accumulation of BaP and EB inside the cell, leading to cell death. ZnO, Al{sub 2}O{sub 3} and TiO{sub 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{sub 2}O{sub 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.

  18. Imaging and identifying defects in nitride semiconductor thin films using a scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Naresh-Kumar, G.; Hourahine, B.; Trager-Cowan, C. [Department of Physics, SUPA, University of Strathclyde, Glasgow (United Kingdom); Vilalta-Clemente, A.; Ruterana, P. [CIMAP UMR 6252 CNRS-ENSICAEN-CEA-UCBN, 6, Caen (France); Gamarra, P.; Lacam, C.; Tordjman, M.; Di Forte-Poisson, M.A. [Thales Research and Technology, III-V Lab, Marcoussis (France); Parbrook, P.J. [Department of Electrical and Electronic Engineering, University of Sheffield (United Kingdom); Day, A.P. [Aunt Daisy Scientific Ltd., Claremont House, High St, Lydney (United Kingdom); England, G. [K. E. Developments Ltd., Cambridge (United Kingdom)

    2012-03-15

    We describe the use of electron channelling contrast imaging (ECCI) - in a field emission scanning electron microscope (SEM) - to reveal and identify defects in nitride semiconductor thin films. In ECCI changes in crystallographic orientation, or changes in lattice constant due to local strain, are revealed by changes in grey scale in an image constructed by monitoring the intensity of backscattered electrons (BSEs) as an electron beam is scanned over a suitably oriented sample. Extremely small orientation changes are detectable, enabling small angle tilt and rotation boundaries and dislocations to be imaged. Images with a resolution of tens of nanometres are obtainable with ECCI. In this paper, we describe the use of ECCI with TEM to determine threading dislocation densities and types in InAlN/GaN heterostructures grown on SiC and sapphire substrates. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    Energy Technology Data Exchange (ETDEWEB)

    Leo, K. W.; Chulan, R. M., E-mail: leo@nm.gov.my; Hashim, S. A.; Baijan, A. H.; Sabri, R. M.; Mohtar, M.; Glam, H.; Lojius, L.; Zahidee, M.; Azman, A.; Zaid, M. [Malaysian Nuclear Agency, Bangi, 43000 Kajang. Selangor (Malaysia)

    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.

  20. Development of Well-Aligned TiO2 Nanotube Arrays to Improve Electron Transport in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Kyung-Ho Chung

    2012-01-01

    Full Text Available We fabricated well-aligned one-dimensional (1-D titania nanotubes (TNT on transparent conducting oxide (TCO by anodization of Ti foil. Different lengths of TNTs were prepared by varying the applied potential (70 V time, and we investigated the performance of these TNTs in dye-sensitized solar cells (DSSCs, transplanted onto a 6 μm TNP adhesion layer. The fabricated TNTs arrays (length 15 μm photoelectrode showed 24% increased efficiency compared to the TNP photoelectrode of 17 μm thickness. We further investigated the performances of DSSCs for the TNTs (1 wt% incorporated TNP photoelectrode and obtained 22% increased efficiency. The increased efficiency of the pure TNTs arrays and TNT-mixed TNP photoelectrodes was attributed to the directional electron movement of TNTs and light scattering effect of the TNT with the decreased rate of back electron transfer. The anodized and fabricated TNTs and DSSCs were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscope (TEM, and electrochemical impedance spectroscopy (EIS.

  1. Development of electron optical system using annular pupils for scanning transmission electron microscope by focused ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Matsutani, Takaomi, E-mail: matutani@ele.kindai.ac.jp [Kinki University, 3-4-1 Kowakae, Higashiosaka, Osaka 577-8502 (Japan); Yasumoto, Tsuchika; Tanaka, Takeo [Osaka Sangyo University, 3-1-1 Nakagaito, Daito, Osaka 574-8530 (Japan); Kawasaki, Tadahiro; Ichihashi, Mikio [Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Ikuta, Takashi [Osaka Electro-Communication University, 18-8 Hatsu-cho, Neyagawa, Osaka 572-8530 (Japan)

    2012-02-01

    Annular pupils for electron optics were produced using a focused ion beam (FIB), enabling an increase in the depth of focus and allowing for aberration-free imaging and separation of the amplitude and phase images in a scanning transmission electron microscope (STEM). Simulations demonstrate that an increased focal depth is advantageous for three-dimensional tomography in the STEM. For a 200 kV electron beam, the focal depth is increased to approximately 100 nm by using an annular pupil with inner and outer semi-angles of 29 and 30 mrad, respectively. Annular pupils were designed with various outer diameters of 40-120 {mu}m and the inner diameter was designed at 80% of the outer diameter. A taper angle varying from 1 Degree-Sign to 20 Degree-Sign was applied to the slits of the annular pupils to suppress the influence of high-energy electron scattering. The fabricated annular pupils were inspected by scanning ion beam microscopy and scanning electron microscopy. These annular pupils were loaded into a STEM and no charge-up effects were observed in the scintillator projection images recorded by a CCD camera.

  2. Does the position of the electron-donating nitrogen atom in the ring system influence the efficiency of a dye-sensitized solar cell? A computational study.

    Science.gov (United States)

    Biswas, Abul Kalam; Barik, Sunirmal; Das, Amitava; Ganguly, Bishwajit

    2016-06-01

    We have reported a number of new metal-free organic dyes (2-6) that have cyclic asymmetric benzotripyrrole derivatives as donor groups with peripheral nitrogen atoms in the ring, fluorine and thiophene groups as π-spacers, and a cyanoacrylic acid acceptor group. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were employed to examine the influence of the position of the donor nitrogen atom and π-conjugation on solar cell performance. The calculated electron-injection driving force (ΔG inject), electron-regeneration driving force (ΔG regen), light-harvesting efficiency (LHE), dipole moment (μ normal), and number of electrons transferred (∆q) indicate that dyes 3, 4, and 6 have significantly higher efficiencies than reference dye 1, which exhibits high efficiency. We also extended our comparison to some other reported dyes, 7-9, which have a donor nitrogen atom in the middle of the ring system. The computed results suggest that dye 6 possesses a higher incident photon to current conversion efficiency (IPCE) than reported dyes 7-9. Thus, the use of donor groups with peripheral nitrogen atoms appears to lead to more efficient dyes than those in which the nitrogen atom is present in the middle of the donor ring system. Graphical Abstract The locations of the nitrogen atoms in the donor groups in the designed dye molecules have an important influence on DSSC efficiency.

  3. Micro-column Scanning Electron Microscope and X-ray Spectrometer (MSEMS) for Planetary Exploration

    Science.gov (United States)

    Ribaya, B.; Niemann, D.; Makarewicz, J.; Clevenson, H.; McKenzie, C.; Nguyen, C.; Blake, D. F.

    2009-12-01

    Scanning Electron Microscopy combined with electron-induced X-ray Fluorescence Spectroscopy (SEM-EDX) is one of the most powerful techniques for characterizing sub-µm surface morphology and composition. In terrestrial laboratories, SEM-EDX is used to elucidate natural processes such as low-temperature diagenesis, thermal or pressure induced metamorphism, volcanism/magmatism, atmosphere/crust interaction and biological activity. Such information would be highly useful for investigating the natural history of the terrestrial planets, satellites and primitive bodies, providing morphological and elemental information that is 2 orders of magnitude higher in resolution than optical techniques. Below we describe the development of a Micro-column Scanning Electron Microscope and X-ray Spectrometer (MSEMS) for flight. The enabling technology of the MSEMS is a carbon nanotube field emission (CNTFE) electron source that is integrated with micro-electro-mechanical-systems (MEMS) - based electron gun and electron optical structures. A hallmark of CNTFE electron sources is their low chromatic aberration, which reduces the need for high accelerating voltages to obtain small spot size. The CNTFE also offers exceptional brightness and nanometer source size, eliminating the need for condenser lenses, making simple electrostatic focusing optics possible. Moreover, the CNT field emission gun (CFEG) at low operating voltage dissipates 103 less power than thermally-assisted Schottky emitters. A key feature of the MSEMS design is the lack of scanning coils. Rather, a piezoelectric sample stage capable of sub-nanometer resolution scans the sample past the fixed crossover of the MSEMS electron beam. We will describe a MEMS-based templating technique for fabricating mechanically and electrically stable miniature CFEGs. Using existing silicon (Si) technology, we fabricated highly controlled and precise MEMS structures for both the CNT cathode and focusing optics for the micro-column. The

  4. Investigation on traceability of 3D Scanning Electron Microscopy based on the Stereo Pair Technique

    DEFF Research Database (Denmark)

    Bariani, Paolo

    The scanning electron microscope (SEM) has a big potential as a metrology instrument for micro and nanotechnology due to its unique combination of three imaging properties: • Lateral ultimate resolution down to 2nm • Large range of possible magnification levels ranging from a few hundred times...... that addresses the performance of 3D topography calculation based on surface topography imaging using secondary electrons and the Stereo Pair Technique....

  5. Joint denoising and distortion correction of atomic scale scanning transmission electron microscopy images

    OpenAIRE

    Berkels, Benjamin; Wirth, Benedikt

    2016-01-01

    Nowadays, modern electron microscopes deliver images at atomic scale. The precise atomic structure encodes information about material properties. Thus, an important ingredient in the image analysis is to locate the centers of the atoms shown in micrographs as precisely as possible. Here, we consider scanning transmission electron microscopy (STEM), which acquires data in a rastering pattern, pixel by pixel. Due to this rastering combined with the magnification to atomic scale, movements of th...

  6. Segmentation of scanning electron microscopy images from natural rubber samples with gold nanoparticles using starlet wavelets

    OpenAIRE

    de Siqueira, Alexandre Fioravante; Cabrera, Flavio Camargo [UNESP; Pagamisse, Aylton; Job,Aldo Eloizo

    2016-01-01

    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...

  7. Investigation on traceability of 3D Scanning Electron Microscopy based on the Stereo Pair Technique

    DEFF Research Database (Denmark)

    Bariani, Paolo

    The scanning electron microscope (SEM) has a big potential as a metrology instrument for micro and nanotechnology due to its unique combination of three imaging properties: • Lateral ultimate resolution down to 2nm • Large range of possible magnification levels ranging from a few hundred times...... that addresses the performance of 3D topography calculation based on surface topography imaging using secondary electrons and the Stereo Pair Technique....

  8. Revealing the Origin of Fast Electron Transfer in TiO2-Based Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Wei, Hai; Luo, Jun-Wei; Li, Shu-Shen; Wang, Lin-Wang

    2016-07-01

    In dye-sensitized solar cells (DSCs), the electron transfer from photoexcited dye molecules to semiconductor substrates remains a major bottleneck. Replacing TiO2 with ZnO is expected to enhance the efficiency of DSCs, owing to the latter possesses a much larger electron mobility, but similar bandgap and band positions as TiO2 remain. However, the record efficiency of ZnO-based DSCs is only 7% compared with 13% of TiO2-based DSCs due to the even slower electron-transfer rate in ZnO-based DSCs, which becomes a long-standing puzzle. Here, we computationally investigate the electron transfer from the dye molecule into ZnO and TiO2, respectively, by performing the first-principles calculations within the frame of the Marcus theory. The predicted electron-transfer rate in the TiO2-based DSC is about 1.15 × 10(9) s(-1), a factor of 15 faster than that of the ZnO-based DSC, which is in good agreement with experimental data. We find that the much larger density of states of the TiO2 compared with ZnO near the conduction band edge is the dominant factor, which is responsible for the faster electron-transfer rate in TiO2-based DSCs. These denser states provide additional efficient channels for the electron transfer. We also provide design principles to boost the efficiency of DSCs through surface engineering of high mobility photoanode semiconductors.

  9. Photocurrents in the ZnO and TiO/sub 2/ photoelectrochemical cells sensitized by xanthene dyes and tetraphenylporphines. Effect of substitution on the electron injection processes

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, M.; Mitsuda, K.; Yoshizawa, N.; Tsubomura, H.

    1981-03-01

    The photocurrents in zinc oxide and titanium dioxide electrodes sensitized by anionic xanthene dyes (Eosine Y, Phloxine B, Erythrosine, and Rose Bengal) and metal tetraphenylporphines were studied in aqueous solutions. The quantum efficiencies of the photocurrents sensitized by anionic xanthene dyes were unaffected by substitution of the dye with various halogen atoms, while those sensitized by the tetraphenylporphines were affected by changing the central metal. It is concluded from these results that the electron injection from the excited xanthene dyes to the semiconductor electrodes is a process so rapid (much less than 0.1 ns) that no internal quenching processes can compete with it, while that from the tetraphynelporphines is relatively slow competing with the internal deactivation processes. It is also concluded that the electron back transfer from the semiconductor conduction band to the oxidized dye decreases the sensitization efficiency.

  10. Electron transfer kinetics in water splitting dye-sensitized solar cells based on core-shell oxide electrodes.

    Science.gov (United States)

    Lee, Seung-Hyun Anna; Zhao, Yixin; Hernandez-Pagan, Emil A; Blasdel, Landy; Youngblood, W Justin; Mallouk, Thomas E

    2012-01-01

    Photoelectrochemical water splitting occurs in a dye-sensitized solar cell when a [Ru(bpy)3]2+-based dye covalently links a porous TiO2 anode film to IrO2 x nH2O nanoparticles. The quantum yield for oxygen evolution is low because of rapid back electron transfer between TiO2 and the oxidized dye, which occurs on a timescale of hundreds of microseconds, When iodide is added as an electron donor, the photocurrent increases, confirming that the initial charge injection efficiency is high. When the porous TiO2 film is coated with a 1-2 nm thick layer of ZrO2 or Nb2O5, both the charge injection rate and back electron transfer rate decrease. The efficiency of the cell increases and then decreases with increasing film thickness, consistent with the trends in charge injection and recombination rates. The current efficiency for oxygen evolution, measured electrochemically in a generator-collector geometry, is close to 100%. The factors that lead to polarization of the photoanode and possible ways to re-design the system for higher efficiency are discussed.

  11. 2,3-Dipentyldithieno[3,2-f:2',3'-h]quinoxaline-Based Organic Dyes for Efficient Dye-Sensitized Solar Cells: Effect of π-Bridges and Electron Donors on Solar Cell Performance.

    Science.gov (United States)

    Huang, Zu-Sheng; Zang, Xu-Feng; Hua, Tao; Wang, Lingyun; Meier, Herbert; Cao, Derong

    2015-09-16

    Five novel metal-free organic dyes DQ1-5 containing a dipentyldithieno[3,2-f:2',3'-h]quinoxaline (DPQ) unit were synthesized and applied in dye-sensitized solar cells (DSSCs), where DPQ was employed as a π-spacer for the first time. Their photophysical, electrochemical, and theoretical calculations and photovoltaic properties were systematically investigated. All the five dyes show broad photoresponse. Especially the absorption edges of DQ3-5 extend to 800 nm on the TiO2 films. The inserted electron-rich unit 3,4-ethylenedioxythiophene or electron-withdrawing group benzothiadiazole (BTD) in DPQ-based dyes can greatly influence the optoelectronic properties of the dyes. In addition, the different electron donors also significantly affect the performance of the DSSCs. Under standard global AM 1.5 solar light conditions, the DQ5 sensitized solar cell obtained a power conversion efficiency of 7.12%. The result indicates that the rigid DPQ-based organic dye is a promising candidate for efficient DSSCs.

  12. Analysis of the dopant distribution in Co-deposited organic thin films by scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Paredes, Yolanda A. [Center of Nanotechnology and Nanoscience, Universidad de las Fuerzas Armadas ESPE, Sangolqui 171-5-31B (Ecuador); Campos, Andrea P.C.; Achete, Carlos A. [DIMAT—INMETRO, Xerém, Duque de Caxias, RJ 25250-020 (Brazil); Cremona, Marco [DIMAT—INMETRO, Xerém, Duque de Caxias, RJ 25250-020 (Brazil); Department of Physics, Pontifícia Universidade Católica do Rio de Janeiro, PUC-Rio, Rio de Janeiro, RJ 22453-970 (Brazil)

    2015-12-01

    Organic light-emitting diodes using phosphorescent dyes (PHOLEDs) have excellent performance, with internal quantum efficiencies approaching 100%. To maximize their performance, PHOLED devices use a conductive organic host material with a sufficiently dispersed phosphorescent guest to avoid concentration quenching. Fac-tris(2-phenylpyridine) iridium, [Ir(ppy){sub 3}] is one of the most widely used green phosphorescent organic compounds. In this work, we used scanning transmission electron microscopy (STEM) equipped with HAADF (high-angle annular dark-field) and EDS (energy dispersive X-ray spectroscopy) detectors to analyze the distribution of the [Ir(ppy){sub 3}] concentration in the host material. This analysis technique, employed for the first time in co-deposited organic thin films, can simultaneously obtain an image and its respective chemical information, allowing for definitive characterization of the distribution and morphology of [Ir(ppy){sub 3}]. The technique was also used to analyze the effect of the vibration of the substrate during thermal co-deposition of the [Ir(ppy){sub 3}] molecules into an organic matrix. - Highlights: • We present a methodology to analyze the dopant distribution in organic thin films. • The method combines HAADF-STEM imaging and EDS X-ray spectroscopy. • Ir(ppy){sub 3} dopant was co-deposited into Spiro2-CBP organic matrix. • The dopant was co-deposited with and without substrate vibration. • Images and chemical information of the dopant were simultaneously obtained.

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

    Science.gov (United States)

    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.

  14. Rotation axes analysis of deformed magnesium based on rotation contour contrast in a scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Kaboli, Shirin; Gauvin, Raynald, E-mail: raynald.gauvin@mcgill.ca

    2015-07-15

    A crystallographic orientation contrast in the form of cross-shaped and intersecting contours was observed in a backscattered electron (BSE) micrograph of deformed magnesium (Mg) grains in a cold field emission scanning electron microscope (CFE-SEM). This contrast was identified as rotation contour contrast (RCC). A model is presented to link the RCC in the BSE micrograph to the channeling contrast in the corresponding channeling pattern. Based on this model, the appearance of the cross-shaped RCC in the BSE micrograph was attributed to the rotation of the crystal about two rotation axes and the RCC was related to a two dimensional angular scan of the corresponding channeling pattern. This model was experimentally validated using the selected area channeling pattern (SACP) technique. The crystallographic directions of the rotation axes were identified using the electron backscatter diffraction (EBSD) technique. - Highlights: • The rotation contour contrast (RCC) was studied in scanning electron microscope (SEM). • The RCC model was developed to link the backscattered electron contrast to the channeling contrast. • The RCC model was validated using the selected area channeling pattern (SACP). • The rotation axes were identified using the electron backscatter diffraction (EBSD)

  15. Morphologic differences observed by scanning electron microscopy according to the reason for pseudophakic IOL explantation

    DEFF Research Database (Denmark)

    Fernandez-Buenaga, Roberto; Alio, Jorge L.; Ramirez, Jose M.

    2015-01-01

    Purpose To compare variations in surface morphology, as studied by scanning electron microscopy (SEM), of explanted intraocular lenses (IOLs) concerning the cause leading to the explantation surgery. Methods In this prospective multicenter study, explanted IOLs were analyzed by SEM and energy-dis...

  16. Calibration-free quantitative surface topography reconstruction in scanning electron microscopy

    NARCIS (Netherlands)

    Faber, E.T.; Martinez-Martinez, D.; Mansilla, C.; Ocelik, V.; De Hosson, J. Th. M.

    2015-01-01

    This work presents a new approach to obtain reliable surface topography reconstructions from 2D Scanning Electron Microscopy (SEM) images. In this method a set of images taken at different tilt angles are compared by means of digital image correlation (DlC). It is argued that the strength of the met

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

    Science.gov (United States)

    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.

  18. Developments in application of light and scanning electron microscopy techniques for cell wall degradation studies.

    NARCIS (Netherlands)

    Engels, F.M.

    1996-01-01

    The results of recent technological developments in light and scanning electron microscopy closely used for research on forage cell wall degradation in ruminants, are reviewed. The indigestibility of forages by rumen microorganisms used to be ascribed mainly to an overall presence of lignin in the p

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

    Science.gov (United States)

    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.

  20. Comparative study of four species of Trichuris roederer, 1761 (Nematoda, Trichurinae by scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Reinalda Marisa Lanfredti

    1995-08-01

    Full Text Available A comparative morphological study of Trichuris travassosi, T. vulpis, T. discolor and T. suis was perfomed using scanning electron microscopy. Cuticular inflation associated with the bacillar band, vulva and male external genital appendages were analyzed. Qualitative and quantitative analyses of these structures were made for each species; they are of taxonomic value.

  1. Scanning electron microscopy and X-ray spectroscopy applied to mycelial phase of sporothrix schenckii

    Directory of Open Access Journals (Sweden)

    M. Thibaut

    1975-04-01

    Full Text Available Scanning electron microscopy applied to the mycelial phase of Sporothrix schenckii shows a matted mycelium with conidia of a regular pattern. X-Ray microanalysis applied in energy dispersive spectroscopy and also in wavelength dispersive spectroscopy reveals the presence of several elements of Mendeleef's classification.

  2. Morphology of Ichthyophonus hoferi assessed by light and scanning electron microscopy

    DEFF Research Database (Denmark)

    Spanggaard, Bettina; Huss, Hans Henrik; Bresciani, J.

    1995-01-01

    The morphology of Ichthyophonus hoferi in vitro at pH 3.5 and 7.0 is described using light and scanning electron microscopy. Only vegetative growth was observed. At pH 3.5, hyphal growth was seen. The hyphae of I. hoferi are characterized by evacuated hyphal walls with the cytoplasm migrating...

  3. Effect of Laser Treatment on Surface Morphology of Indirect Composite Resin: Scanning Electron Microscope (SEM) Evaluation

    OpenAIRE

    Mirzaie, Mansore; Garshasbzadeh, Nazanin Zeinab; Yassini, Esmaeil; Shahabi, Sima; Chiniforush, Nasim

    2013-01-01

    Introduction: The aim of this study was to evaluate and compare the Scanning electron microscope (SEM) of indirect composite conditioned by Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser, Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) laser and Carbon Dioxide (CO2) laser.

  4. Scanning electron microscopy of dentition: methodology and ultrastructural morphology of tooth wear.

    Science.gov (United States)

    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.

  5. Observation of microporous cesium salts of 12-tungstosilicic acid using scanning transmission electron microscopy.

    Science.gov (United States)

    Hiyoshi, Norihito; Kamiya, Yuichi

    2015-06-21

    Heteropolyanions and their arrays in microporous cesium salts of 12-tungstosilicic acid, Cs2.5H1.5[SiW12O40] and Cs4.0[SiW12O40], were observed by aberration-corrected scanning transmission electron microscopy. Microstructures that form micropores in the polyoxometalates were visualized.

  6. Alcoholic liver injury: defenestration in noncirrhotic livers--a scanning electron microscopic study

    DEFF Research Database (Denmark)

    Horn, T; Christoffersen, P; Henriksen, Jens Henrik Sahl

    1987-01-01

    The fenestration of hepatic sinusoidal endothelial cells in 15 needle biopsies obtained from chronic alcoholics without cirrhosis was studied by scanning electron microscopy. As compared to nonalcoholics, a significant reduction in the number of fenestrae and porosity of the sinusoidal lining wall...

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

    Science.gov (United States)

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

    2017-01-01

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

  8. Characterizing individual particles on tree leaves using computer automated scanning electron microscopy

    Science.gov (United States)

    D. L. Johnson; D. J. Nowak; V. A. Jouraeva

    1999-01-01

    Leaves from twenty-three deciduous tree species and five conifer species were collected within a limited geographic range (1 km radius) and evaluated for possible application of scanning electron microscopy and X-ray microanalysis techniques of individual particle analysis (IPA). The goal was to identify tree species with leaves suitable for the automated...

  9. Carbon-fiber tips for scanning probe microscopes and molecular electronics experiments

    NARCIS (Netherlands)

    Rubio-Bollinger, G.; Castellanos-Gomez, A.; Bilan, S.; Zotti, L.A.; Arroyo, C.R.; Agraït, N.; Cuevas, J.

    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 t

  10. The mechanism of PTFE and PE friction deposition: a combined scanning electron and scanning force microscopy study on highly oriented polymeric sliders

    NARCIS (Netherlands)

    Schaeben, H.; Vancso, G. Julius

    1998-01-01

    The mechanism of friction deposition of polytetrafluoroethylene (PTFE) and polyethylene (PE) was studied by scanning electron (SEM) and scanning force microscopy (SFM) on the worn surfaces of PTFE and PE sliders that were used in friction deposition on glass substrates. These surfaces exhibited a fi

  11. The mechanism of PTFE and PE friction deposition: a combined scanning electron and scanning force microscopy study on highly oriented polymeric sliders

    NARCIS (Netherlands)

    Schönherr, Holger; Schaeben, H.; Vancso, Gyula J.

    1998-01-01

    The mechanism of friction deposition of polytetrafluoroethylene (PTFE) and polyethylene (PE) was studied by scanning electron (SEM) and scanning force microscopy (SFM) on the worn surfaces of PTFE and PE sliders that were used in friction deposition on glass substrates. These surfaces exhibited a

  12. 4D scanning ultrafast electron microscopy: visualization of materials surface dynamics.

    Science.gov (United States)

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

    2011-05-25

    The continuous electron beam of conventional scanning electron microscopes (SEM) limits the temporal resolution required for the study of ultrafast dynamics of materials surfaces. Here, we report the development of scanning ultrafast electron microscopy (S-UEM) as a time-resolved method with resolutions in both space and time. The approach is demonstrated in the investigation of the dynamics of semiconducting and metallic materials visualized using secondary-electron images and backscattering electron diffraction patterns. For probing, the electron packet was photogenerated from the sharp field-emitter tip of the microscope with a very low number of electrons in order to suppress space-charge repulsion between electrons and reach the ultrashort temporal resolution, an improvement of orders of magnitude when compared to the traditional beam-blanking method. Moreover, the spatial resolution of SEM is maintained, thus enabling spatiotemporal visualization of surface dynamics following the initiation of change by femtosecond heating or excitation. We discuss capabilities and potential applications of S-UEM in materials and biological science.

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

    Science.gov (United States)

    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.

  14. Depth dose characteristics of electron beams released from a scanning type racetrack microtron treatment machine

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Tomoharu [National Cancer Center, Tokyo (Japan). Hospital

    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. (author)

  15. Geometries, Electronic Structures, And Spectral Properties Of Some Metal Free Phthalonitrile Derivatives For Enhancement Of The Dye Sensitized Solar Cells

    Science.gov (United States)

    Anbarasan, P. M.

    2010-08-01

    New technologies for direct solar energy conversion have gained more attention in the last few years. In particular, Dye Sensitized Solar Cells (DSSCs) are promising in terms of efficiency and low cost [1,2]. Benefited from systematic device engineering and continuous material innovation, a state of the art DSC with a ruthenium sensitizer has achieved a validated efficiency of 11.1%[3] measured under the air mass 1.5 global (AM1.5G) conditions. The optimized geometries of the 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile are shown in Fig. 1(a). The frontier molecular orbitals (MO) energies of the dyes 3, 4 Pyridinedicarbonitrile, 3-Nitrophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile are shown in Fig. 1(b). The HOMO-LUMO gap of the dye 3, 4 Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile in vacuum is 5.96 eV, 5.54 eV, 5.57 eV, 5.76 eV respectively. The geometries, electronic structures, polarizabilities, and hyperpolarizabilities of dyes 3, 4-Pyridinedicarbonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile were studied by using density functional theory with hybrid functional B3LYP, and the UV-Vis spectra were investigated by using TDDFT methods. The NBO results suggest that 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile 4-Aminophthalonitrile and 4-Methylphthalonitrile are all (D-pi-A) systems. The calculated isotropic polarizability of 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile is. 85.76, 112.72, 26.63 and 115.13 a.u., respectively. The calculated polarizability anisotropy invariant of 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile is 74.451, 83.533, 62.653 and 88.526 a.u., respectively. The hyperpolarizabilities of 3, 4-Pyridinedicarbonitrile, 3-Aminophthalonitrile, 4-Aminophthalonitrile and 4-Methylphthalonitrile is 0

  16. Inhalation Toxicology of Red and Violet Dye Mixtures, Chamber Concentration and Particle Size Distribution Report

    Science.gov (United States)

    1990-12-01

    1.5 lam). These are the anthraquirione dyes, with corresponding crystalline structures . Figure 5. Scanning Electron Microscopy (SEM) of DO3. 1 18...an amorphic structure as opposed to the crystalline structures The component dye 0D3 of the VDM degrades if not stored at 4 ’C. 20 I " • i III I III

  17. Serial block face scanning electron microscopy--the future of cell ultrastructure imaging.

    Science.gov (United States)

    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.

  18. A different approach for determining the responsivity of n+p detectors using scanning electron microscopy

    Institute of Scientific and Technical Information of China (English)

    Omeime Xerviar Esebamen; G(o)ran Thungstr(o)m; Hans-Erik Nilsson

    2012-01-01

    This paper explores an alternative to the standard method of studying the responsivities(the input-output gain) and other behaviours of detectors at low electron energy The research does not aim to compare the results of differently doped n+p detectors; its purpose is to provide an alternative characterization method (using scanning electron microscopy) to those used in previous studies on the responsivity of n+p doped detectors as a function of the electron radiation energy and other interface parameters.

  19. Correlative In Vivo 2 Photon and Focused Ion Beam Scanning Electron Microscopy of Cortical Neurons

    Science.gov (United States)

    Maco, Bohumil; Holtmaat, Anthony; Cantoni, Marco; Kreshuk, Anna; Straehle, Christoph N.; Hamprecht, Fred A.; Knott, Graham W.

    2013-01-01

    Correlating in vivo imaging of neurons and their synaptic connections with electron microscopy combines dynamic and ultrastructural information. Here we describe a semi-automated technique whereby volumes of brain tissue containing axons and dendrites, previously studied in vivo, are subsequently imaged in three dimensions with focused ion beam scanning electron microcopy. These neurites are then identified and reconstructed automatically from the image series using the latest segmentation algorithms. The fast and reliable imaging and reconstruction technique avoids any specific labeling to identify the features of interest in the electron microscope, and optimises their preservation and staining for 3D analysis. PMID:23468982

  20. Correlative in vivo 2 photon and focused ion beam scanning electron microscopy of cortical neurons.

    Directory of Open Access Journals (Sweden)

    Bohumil Maco

    Full Text Available Correlating in vivo imaging of neurons and their synaptic connections with electron microscopy combines dynamic and ultrastructural information. Here we describe a semi-automated technique whereby volumes of brain tissue containing axons and dendrites, previously studied in vivo, are subsequently imaged in three dimensions with focused ion beam scanning electron microcopy. These neurites are then identified and reconstructed automatically from the image series using the latest segmentation algorithms. The fast and reliable imaging and reconstruction technique avoids any specific labeling to identify the features of interest in the electron microscope, and optimises their preservation and staining for 3D analysis.

  1. Effect of dyeing on antibacterial efficiency of silver coated cotton fabrics

    Science.gov (United States)

    Shahidi, Sheila; Rezaee, Sahar; Hezavehi, Emadaldin

    2014-04-01

    Despite numerous investigations during recent decades in the field of antimicrobial treating textile fibers using silver, many obscurities remain regarding the durability and dyeing ability and the influences of dyeing on the antimicrobial effectiveness of silver-treated fibers. In this research work, the cotton fabrics were sputtered using DC magnetron sputtering system for different times of exposure by silver. Then the silver coated samples were dyed by different classes of synthetic and natural dyes. The dye ability of coated samples was compared with untreated cotton. The reflective spectrophotometer was used for this purpose. The morphology of the cotton fabrics before and after dyeing was observed using a scanning electron microscope (SEM). The antibacterial activity of samples before and after dyeing, were investigated and compared. For antibacterial investigation, the antibacterial counting tests were used. It was concluded that, dyeing does not have any negative effect on antibacterial activity of coated samples and very good antibacterial activity was achieved after dyeing.

  2. The Effect of Donor Group Rigidification on the Electronic and Optical Properties of Arylamine-Based Metal-Free Dyes for Dye-Sensitized Solar Cells: A Computational Study.

    Science.gov (United States)

    Estrella, Liezel L; Balanay, Mannix P; Kim, Dong Hee

    2016-07-28

    One of the most significant aspects in the development of dye-sensitized solar cells is the exploration and design of high-efficiency and low-cost dyes. This paper reports the theoretical design of various triphenylamine analogues, wherein the central nitrogen moiety establishes an sp(2)-hybridization, which endows a significant participation in the charge-transfer properties. Density functional theory (DFT) and time-dependent DFT methodologies were utilized to investigate the geometry, electronic structure, photochemical properties, and electrochemical properties of these dyes. Different exchange-correlation functionals were initially evaluated to establish a proper methodology for calculating the excited-state energy of the reference dye, known as DIA3. Consequently, TD-LC-ωPBE with a damping parameter of 0.175 Bohr(-1) best correlates with the experimental value. Four new dyes, namely, Dhk1, Dhk2, Dhk3, and Dhk4, were designed by modifying the rigidity of the donor moiety. According to the results, altering the type and position of binding in the donor group leads to distinct planarity of the dyes, which significantly affects their properties. The designed Dhk4 dye showed more red-shifted and broadened absorption spectra owing to the enhanced coplanarity between its donor and π-bridge moiety, which brings an advantage for its potential use as sensitizer for photovoltaic applications.

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

    CERN Document Server

    Tate, Mark W; Chamberlain, Darol; Nguyen, Kayla X; Hovden, Robert M; 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

    2015-01-01

    We describe a hybrid pixel array detector (EMPAD - electron microscope pixel array detector) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128 x 128 pixel detector consists of a 500 um thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit (ASIC). 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 loc...

  4. A correlative light microscopic, transmission and scanning electron microscopic study of the dorsum of human tongue.

    Science.gov (United States)

    Boshell, J L; Wilborn, W H; Singh, B B

    1980-01-01

    The dorsum of the human tongue has three types of papillae, filiform, fungiform and circumvallate. Some investigators have studied these by light and transmission electron microscopy. Since knowledge of the morphology through studies by scanning of the morphology through studies by scanning electron microscopy (SEM) is scant, this investigation was started with the purpose of studying human tongues at different ages. One fetal tongue and portions of three tongues from newborns were removed. Additional specimens were biopsied from the anterior region of three adult tongues. Samples were processed routinely for light microscopy, transmission electron microscoy (TEM) and scanning electron microscopy (SEM). Two distinct features were evident on the fetal tongue. The first was that the surface epithelial layer of the tongue appeared to be periderm. The second was that fungiform papillae began their development earlier than filiform. At birth, the putative periderm had disappeared and a few filiform papillae were observed. On the adult tongue, filiform papillae were numerous and were comprised of two cell populations. One cell population contained numerous keratohyalin granules (KHG). The KHG were two types, eosinophilic and basophilic. Ultrastructurally, the eosinophilic granules were less electron dense and larger in size than the basophilic KHG.

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

    Science.gov (United States)

    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.

  6. Zinc deficiency in the 11 day rat embryo: a scanning and transmission electron microscope study

    Energy Technology Data Exchange (ETDEWEB)

    Harding, A.J.; Dreosti, I.E.; Tulsi, R.S.

    1988-01-01

    Zinc deficient rat embryos were obtained on the 11th day of pregnancy and examined by scanning and transmission electron microscopy. Scanning electron microscopy revealed an increase in the number of deformed embryos, as well as embryonic growth retardation. In addition, the epithelium of zinc deficient embryos displayed a marked increase in surface microvilli, as well as the presence of blebbing. Transmission electron microscopy indicated extensive cell death in the neural epithelium which was apparently more severely damaged by zinc deficiency than were mesenchymal cells. Mitochondrial cristae were affected to a greater degree than any other membrane of the cell and cristael disintegration appeared to represent the principal cellular lesion preceding necrosis of neural cells and neural tube teratology. 29 references, 4 figures, 1 table.

  7. Scanning and transmission electron microscopic study of equine infectious anemia virus.

    Science.gov (United States)

    Gonda, M A; Charman, H P; Walker, J L; Coggins, L

    1978-05-01

    Scanning and transmission electron microscopy were used to study in detail the morphogenesis and replication of equine infectious anemia virus (EIAV) in cultured, persistently infected equine fetal kidney fibroblasts. The EIAV was shown by thin-section electron microscopy to resemble morphologically more closely the members of the genus Lenti-virus in the family Retroviridae than other genera. Scanning electron microscopy demonstrated budding virus on only about 5% of the equine fetal kidney fibroblasts; however, the entire surface of these cells was involved in viral replication. Except where virus budding was observed, EIAV-infected cells were smooth and free of the topographic surface alterations characteristic of cells transformed by type C retroviruses. The morphologic relationship of EIAV and pathologic manifestations of EIAV infection to those of other Retroviridae are discussed.

  8. Three-dimensional optical transfer functions in the aberration-corrected scanning transmission electron microscope.

    Science.gov (United States)

    Jones, L; Nellist, P D

    2014-05-01

    In the scanning transmission electron microscope, hardware aberration correctors can now correct for the positive spherical aberration of round electron lenses. These correctors make use of nonround optics such as hexapoles or octupoles, leading to the limiting aberrations often being of a nonround type. Here we explore the effect of a number of potential limiting aberrations on the imaging performance of the scanning transmission electron microscope through their resulting optical transfer functions. In particular, the response of the optical transfer function to changes in defocus are examined, given that this is the final aberration to be tuned just before image acquisition. The resulting three-dimensional optical transfer functions also allow an assessment of the performance of a system for focal-series experiments or optical sectioning applications. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

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

    Energy Technology Data Exchange (ETDEWEB)

    Pelliccione, M. [Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Physics, University of California, Santa Barbara, Santa Barbara, California 93106 (United States); Bartel, J.; Goldhaber-Gordon, D. [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305 (United States); Sciambi, A. [Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Pfeiffer, L. N.; West, K. W. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

    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.

  10. Effect of surface mechanical finishes on charging ability of electron irradiated PMMA in a scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Rondot, Sebastien, E-mail: sebastien.rondot@univ-reims.fr [Groupe de Recherche en Sciences pour l' Ingenieur, EA4301, Faculte des Sciences, BP 1039, 51687 Reims Cedex 2 (France); Jbara, Omar [Groupe de Recherche en Sciences pour l' Ingenieur, EA4301, Faculte des Sciences, BP 1039, 51687 Reims Cedex 2 (France); Fakhfakh, Slim [LaMaCop, Faculte des Sciences de SFAX, Route Soukra Km 3, BP 1171, C.P 3000 Sfax (Tunisia); Belkorissat, Redouane; Patat, Jean Marc [Groupe de Recherche en Sciences pour l' Ingenieur, EA4301, Faculte des Sciences, BP 1039, 51687 Reims Cedex 2 (France)

    2011-10-01

    Charging of Polymethyl Methacrylate insulators (PMMA), in a scanning electron microscope (SEM) is studied owing to a time resolved current method. This method allows the evolution of trapped charge versus time and the charging time constant to be deduced. The effect of surface roughness change on the ability of PMMA to trapped charge is highlighted. The results show that the trapped charge at the steady state decreases when the roughness increases in the micrometer range while the time constant of charging increases with surface roughness. This behaviour is due to the increase of leakage current and/or enhanced secondary electron emission (SEE). On the one hand, surface mechanical finishes allows, the build up charge in insulators submitted to an electron bombardment to be lowered. On the other hand this treatment allows the secondary electron emission to be raised for some specific applications.

  11. Spacer Thickness-Dependent Electron Transport Performance of Titanium Dioxide Thick Film for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Reda E. El-Shater

    2015-01-01

    Full Text Available A titanium dioxide (P25 film was deposited by cast coating as conductive photoelectrode and subsequently immersed in dye solution (N719 to fabricate the photoanode of dye-sensitized solar cells (DSSCs. A plastic spacer was used as a separation and sealant layer between the photoanode and the counter electrode. The effect of the thickness of this spacer on the transfer of electrons in the liquid electrolyte of the DSSCs was studied by means of both IV curves and electrochemical impedance. Using a spacer thickness range of 20 μm to 50 μm, efficiency ranges from 3.73% to 7.22%. The highest efficiency of 7.22% was obtained with an optimal spacer thickness of 40 μm.

  12. Geometric and chelation influences on the electronic structure and optical properties of tetra(carboxylic acid)phenyleneethynylene dyes.

    Science.gov (United States)

    Berlin, Asher; Risko, Chad; Ratner, Mark A

    2008-05-08

    A quantum-chemical study on the consequences of geometric modification and chelation on the electronic structure and optical properties of a tetra(carboxylic acid)phenyleneethynylene dye, of interest for chemical sensing applications, is presented. Rotation within the central biphenylene and complexation with divalent metal ions--in particular Cu2+--lead to notable changes in the absorption and emission profiles. Calculations at both the density functional theory (DFT) and Hartree-Fock (HF) levels are used to evaluate geometric potential energy surfaces for rotation within the central biphenylene unit; HF coupled with configuration interaction singles (HF-CIS) is used to investigate the first excited state of the dye. Time-dependent DFT (TDDFT) calculations are employed to assess changes in optical absorption and fluorescence as a function of geometry and chelation.

  13. A scanning drift tube apparatus for spatio-temporal mapping of electron swarms

    CERN Document Server

    Korolov, I; Bastykova, N Kh; Donko, Z

    2016-01-01

    A "scanning" drift tube apparatus, capable of mapping of the spatio-temporal evolution of electron swarms, developing between two plane electrodes under the effect of a homogeneous electric field, is presented. The electron swarms are initiated by photoelectron pulses and the temporal distributions of the electron flux are recorded while the electrode gap length (at a fixed electric field strength) is varied. Operation of the system is tested and verified with argon gas, the measured data are used for the evaluation of the electron bulk drift velocity. The experimental results for the space-time maps of the electron swarms - presented here for the first time - also allow clear observation of deviations from hydrodynamic transport. The swarm maps are also reproduced by particle simulations.

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

    Science.gov (United States)

    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.

  15. Improved electron transportation of dye-sensitized solar cells using uniform mixed CNTs-TiO{sub 2} photoanode prepared by a new polymeric gel process

    Energy Technology Data Exchange (ETDEWEB)

    Bakhshayesh, A. M.; Mohammadi, M. R., E-mail: mrm41@cam.ac.uk; Masihi, N.; Akhlaghi, M. H. [Sharif University of Technology, Department of Materials Science and Engineering (Iran, Islamic Republic of)

    2013-09-15

    A new facile strategy for fabrication of high surface area electrode in the form of mixtures of coated carbon nanotubes (CNTs) and TiO{sub 2} nanoparticles with various weight ratios is reported. The so-called polymeric gel process was used to deposit thick film containing uniform distribution of TiO{sub 2} nanoparticles and coated CNTs with high porosity by dip coating for dye-sensitized solar cells (DSSCs) applications. Based on simultaneous differential thermal analysis, the minimum annealing temperature to obtain inorganic- and organic-free films was determined at 500 Degree-Sign C. X-ray diffraction analysis revealed that deposited films were composed of primary nanoparticles with crystallite size in the range 21-45 nm. Field emission scanning electron microscope images showed that deposited films had porous morphology containing uniform spherical particles with diameter around 2.5 {mu}m and coated CNTs with TiO{sub 2} nanoparticles (TNTs). The spherical particles were composed of small nanoparticles ({approx}60 nm), improving light scattering and dye loading of the DSSC. Moreover, TNTs were uniformly incorporated into the electrodes, improving electron transportation. X-ray photoelectron spectroscopy was presented as an obvious proof for the inclusion of CNTs into the TiO{sub 2} matrix. Ultraviolet-visible spectroscopy showed that CNT introduction enhanced the visible light absorption of photoanode by shifting the absorption onset to visible light region. An enhancement of power conversion efficiency (PCE) from 6.53 % for pure TiO{sub 2} to 7.38 % for CNT-TiO{sub 2} electrode containing 0.025 wt% CNTs was achieved. This well-incorporated study would present an intellectual development in the fabrication of low-cost CNT consolidated DSSCs with high PCE.

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

    Science.gov (United States)

    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.

  17. Transmission and scanning electron microscopy confirm that bone microstructure is similar in osteopenic and osteoporotic patients.

    Science.gov (United States)

    Gül, Orkun; Atik, O Sahap; Erdoğan, Deniz; Göktaş, Güleser; Elmas, Ciğdem

    2013-01-01

    The objective was to confirm the finding of "Bone microstructure is similar in osteopenic and osteoporotic patients with femoral neck fracture." obtained in previous "light microscopy study", which was new and important data. Fourteen patients (5 males, 9 females) who were admitted with proximal femoral fracture following low energy trauma (patients who participated in the light microscopy study) were included. The patients were divided into two groups based on the bone mineral density (BMD) measurement, including osteopenic group (n=7, mean age 69 years; range 63 to 74 years) and osteoporotic group (n=7, mean age 74.1 years; range 67 to 78 years). Cortical and trabecular bone samples were taken from the patients who underwent endoprosthesis during partial hip arthroplasty and these samples were analyzed using transmission electron microscopy and scanning electron microscopy evaluations which are more sophisticated higher resolution techniques. The mean cortical bone thickness was 3622.14 mm in osteopenic group and 2323.14 mm in osteoporotic group (pelectron microscopy and scanning electron microscopy evaluations revealed similar findings for both groups. Although a significant difference in cortical thickness was found between the groups, transmission and scanning electron microscopy confirmed that bone microstructure shared similar characteristics in osteopenic and osteoporotic patients with low-energy femoral neck fracture, as it was in previous light microscopy study.

  18. A small electron donor in cobalt complex electrolyte significantly improves efficiency in dye-sensitized solar cells

    Science.gov (United States)

    Hao, Yan; Yang, Wenxing; Zhang, Lei; Jiang, Roger; Mijangos, Edgar; Saygili, Yasemin; Hammarström, Leif; Hagfeldt, Anders; Boschloo, Gerrit

    2016-12-01

    Photoelectrochemical approach to solar energy conversion demands a kinetic optimization of various light-induced electron transfer processes. Of great importance are the redox mediator systems accomplishing the electron transfer processes at the semiconductor/electrolyte interface, therefore affecting profoundly the performance of various photoelectrochemical cells. Here, we develop a strategy--by addition of a small organic electron donor, tris(4-methoxyphenyl)amine, into state-of-art cobalt tris(bipyridine) redox electrolyte--to significantly improve the efficiency of dye-sensitized solar cells. The developed solar cells exhibit efficiency of 11.7 and 10.5%, at 0.46 and one-sun illumination, respectively, corresponding to a 26% efficiency improvement compared with the standard electrolyte. Preliminary stability tests showed the solar cell retained 90% of its initial efficiency after 250 h continuous one-sun light soaking. Detailed mechanistic studies reveal the crucial role of the electron transfer cascade processes within the new redox system.

  19. Separation of image-distortion sources and magnetic-field measurement in scanning electron microscope (SEM).

    Science.gov (United States)

    Płuska, Mariusz; Czerwinski, Andrzej; Ratajczak, Jacek; Katcki, Jerzy; Oskwarek, Lukasz; Rak, Remigiusz

    2009-01-01

    The electron-microscope image distortion generated by electromagnetic interference (EMI) is an important problem for accurate imaging in scanning electron microscopy (SEM). Available commercial solutions to this problem utilize sophisticated hardware for EMI detection and compensation. Their efficiency depends on the complexity of distortions influence on SEM system. Selection of a proper method for reduction of the distortions is crucial. The current investigations allowed for a separation of the distortions impact on several components of SEM system. A sum of signals from distortion sources causes wavy deformations of specimen shapes in SEM images. The separation of various reasons of the distortion is based on measurements of the periodic deformations of the images for different electron beam energies and working distances between the microscope final aperture and the specimen. Using the SEM images, a direct influence of alternating magnetic field on the electron beam was distinguished. Distortions of electric signals in the scanning block of SEM were also separated. The presented method separates the direct magnetic field influence on the electron beam below the SEM final aperture (in the chamber) from its influence above this aperture (in the electron column). It also allows for the measurement of magnetic field present inside the SEM chamber. The current investigations gave practical guidelines for selecting the most efficient solution for reduction of the distortions.

  20. Contrast and decay of cathodoluminescence from phosphor particles in a scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Engelsen, Daniel den; Harris, Paul G.; Ireland, Terry G., E-mail: terry.ireland@brunel.ac.uk; Fern, George R.; Silver, Jack

    2015-10-15

    Cathodoluminescence (CL) studies are reported on phosphors in a field emission scanning electron microscope (FESEM). ZnO: Zn and other luminescent powders manifest a bright ring around the periphery of the particles: this ring enhances the contrast. Additionally, particles resting on top of others are substantially brighter than underlying ones. These phenomena are explained in terms of the combined effects of electrons backscattered out of the particles, together with light absorption by the substrate. The contrast is found to be a function of the particle size and the energy of the primary electrons. Some phosphor materials exhibit a pronounced comet-like structure at high scan rates in a CL-image, because the particle continues to emit light after the electron beam has moved to a position without phosphor material. Image analysis has been used to study the loss of brightness along the tail and hence to determine the decay time of the materials. The effect of phosphor saturation on the determination of decay times by CL-microscopy was also investigated. - Highlights: • Contrast enhancement are observed in secondary electron and cathodoluminescent images of phosphor particles sitting on top of others. • Backscattered electrons largely explain the observed contrast enhancement. • After glow effects in CL-micrographs of phosphors enable the determination of decay times. • Phosphor saturation can be used to determine the decay time of individual spectral transitions.

  1. Quantum dynamical simulation of photoinduced electron transfer processes in dye-semiconductor systems: theory and application to coumarin 343 at TiO2

    Science.gov (United States)

    Li, Jingrui; Kondov, Ivan; Wang, Haobin; Thoss, Michael

    2015-04-01

    A recently developed methodology to simulate photoinduced electron transfer processes at dye-semiconductor interfaces is outlined. The methodology employs a first-principles-based model Hamiltonian and accurate quantum dynamics simulations using the multilayer multiconfiguration time-dependent Hartree approach. This method is applied to study electron injection in the dye-semiconductor system coumarin 343-TiO2. Specifically, the influence of electronic-vibrational coupling is analyzed. Extending previous work, we consider the influence of Dushinsky rotation of the normal modes as well as anharmonicities of the potential energy surfaces on the electron transfer dynamics.

  2. Experimental Route to Scanning Probe Hot Electron Nanoscopy (HENs) Applied to 2D Material

    KAUST Repository

    Giugni, Andrea

    2017-06-09

    This paper presents details on a new experimental apparatus implementing the hot electron nanoscopy (HENs) technique introduced for advanced spectroscopies on structure and chemistry in few molecules and interface problems. A detailed description of the architecture used for the laser excitation of surface plasmons at an atomic force microscope (AFM) tip is provided. The photogenerated current from the tip to the sample is detected during the AFM scan. The technique is applied to innovative semiconductors for applications in electronics: 2D MoS2 single crystal and a p-type SnO layer. Results are supported by complementary scanning Kelvin probe microscopy, traditional conductive AFM, and Raman measurements. New features highlighted by HEN technique reveal details of local complexity in MoS2 and polycrystalline structure of SnO at nanometric scale otherwise undetected. The technique set in this paper is promising for future studies in nanojunctions and innovative multilayered materials, with new insight on interfaces.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  5. Microstructure of the water spider (Argyroneta aquatica using the scanning electron microscope

    Directory of Open Access Journals (Sweden)

    Jung-Hoon Kang

    2014-12-01

    Full Text Available This study is aimed to identify the external features of the water spiders (Argyroneta aquatica collected from “The Natural Monument No. 412 Yeoncheon Eundaeri Water Spider Habitat” through observation of their microstructures using a scanning electron microscope. There is no study on the microstructures of the water spiders excluding several studies on protection plans and ecological investigations, thus giving this study considerable academic significance. Based on the scanning electron microscopy analysis, the water spider has eight simple eyes, and both of its lateral simple eyes are stuck together. A lateral bump was confirmed on the upper jaw, and the pedipalps had six joints and the legs had seven joints. The abdomen and sternum of A. aquatica have more hairs compared with those of land spiders, and its structure shows an elongated area of contact with the air bell so that the air bell can become attached to the abdomen better.

  6. Morphological changes of the hair roots in alopecia areata: a scanning electron microscopic study.

    Science.gov (United States)

    Karashima, Tadashi; Tsuruta, Daisuke; Hamada, Takahiro; Ishii, Norito; Ono, Fumitake; Ueda, Akihiro; Abe, Toshifumi; Nakama, Takekuni; Dainichi, Teruki; Hashimoto, Takashi

    2013-12-01

    Alopecia areata is a chronic inflammatory condition causing non-scarring patchy hair loss. Diagnosis of alopecia areata is made by clinical observations, hair pluck test and dermoscopic signs. However, because differentiation from other alopecia diseases is occasionally difficult, an invasive diagnostic method using a punch biopsy is performed. In this study, to develop a reliable, less invasive diagnostic method for alopecia areata, we performed scanning electron microscopy of the hair roots of alopecia areata patients. This study identified four patterns of hair morphology specific to alopecia areata: (I) long tapering structure with no accumulation of scales; (II) club-shaped hair root with fine scales; (III) proximal accumulation of scales; and (IV) sharp tapering of the proximal end of hair. On the basis of these results, we can distinguish alopecia areata by scanning electron microscopic observation of the proximal end of the hair shafts. © 2013 Japanese Dermatological Association.

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

    Science.gov (United States)

    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.

  8. Third-Order Nonlinear Optical Property of POLY(HEXA-2,4-DIYNYLENE-1,6-DIOXYDICINNAMATE) Containing a Polar Azo Dye, Determined by Z-Scan Technique

    Science.gov (United States)

    Ortega, Alejandra; Perez-Martinez, Ana Laura; Ogawa, Takeshi; Smith, Francis; Walser, Ardie; Dorsinville, Roger

    A highly-conjugated polar dye with three aromatic rings connected with azo groups was prepared and it was incorporated in polycinnamate. It showed a third-order nonlinear susceptibility of 8 × 10-10 esu determined by a Z-scan technique. The unpoled and poled films show the same susceptibility indicating the polymer film could not be poled. The open aperture Z-scan showed negligible two-photon absorption at 1064 nm.

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

    Science.gov (United States)

    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.

  10. A density-functional theory study of tip electronic structures in scanning tunneling microscopy.

    Science.gov (United States)

    Choi, Heesung; Longo, Roberto C; Huang, Min; Randall, John N; Wallace, Robert M; Cho, Kyeongjae

    2013-03-15

    In this work, we report a detailed analysis of the atomic and electronic structures of transition metal scanning tunneling microscopy tips: Rh, Pd, W, Ir, and Pt pyramidal models, and transition metal (TM) atom tips supported on the W surface, by means of ab initio density-functional theory methods. The d electrons of the apex atoms of the TM tips (Rh, Pd, W, Ir, and Pt tetrahedral structures) show different behaviors near the Fermi level and, especially for the W tip, dz(2) states are shown to be predominant near the Fermi level. The electronic structures of larger pyramidal TM tip structures with a single apex atom are also reported. Their obtained density of states are thoroughly discussed in terms of the different d-electron occupations of the TM tips.

  11. Scanning electron microscopy of cells and tissues under fully hydrated conditions.

    Science.gov (United States)

    Thiberge, Stephan; Nechushtan, Amotz; Sprinzak, David; Gileadi, Opher; Behar, Vered; Zik, Ory; Chowers, Yehuda; Michaeli, Shulamit; Schlessinger, Joseph; Moses, Elisha

    2004-03-09

    A capability for scanning electron microscopy of wet biological specimens is presented. A membrane that is transparent to electrons protects the fully hydrated sample from the vacuum. The result is a hybrid technique combining the ease of use and ability to see into cells of optical microscopy with the higher resolution of electron microscopy. The resolution of low-contrast materials is approximately 100 nm, whereas in high-contrast materials the resolution can reach 10 nm. Standard immunogold techniques and heavy-metal stains can be applied and viewed in the fluid to improve the contrast. Images present a striking combination of whole-cell morphology with a wealth of internal details. A possibility for direct inspection of tissue slices transpires, imaging only the external layer of cells. Simultaneous imaging with photons excited by the electrons incorporates data on material distribution, indicating a potential for multilabeling and specific scintillating markers.

  12. Investigation on gradient material fabrication with electron beam melting based on scanning track control

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new electron beam control system was developed in a general vacuum electron beam machine by assembling with industrial control computer, programmable logic control (PLC), deflection coil, data acquisition card, power amplifier, etc. In this control system, scanning track and energy distribution of electron beam could be edited off-line, real-time adjusted and controlled on-line. Ti-Mo gradient material (GM) with high temperature resistant was fabricated using the technology of electron beam melting. The melting processes include three steps, such as preheating, melting, and homogenizing. The results show that the GM prepared by melting technology has fine appearance, and it has good integrated interface with the Ti alloy. Mo and Ti elements are gradually distributed in the interface of the gradient material. The microstructure close to the Ti alloy base metal is α+β basket-waver grain, and the microstructure close to the GM is a single phase of β solid solution.

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

    Science.gov (United States)

    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.

  14. SEM analysis of ionizing radiation effects in linear integrated circuits. [Scanning Electron Microscope

    Science.gov (United States)

    Stanley, A. G.; Gauthier, M. K.

    1977-01-01

    A successful diagnostic technique was developed using a scanning electron microscope (SEM) as a precision tool to determine ionization effects in integrated circuits. Previous SEM methods radiated the entire semiconductor chip or major areas. The large area exposure methods do not reveal the exact components which are sensitive to radiation. To locate these sensitive components a new method was developed, which consisted in successively irradiating selected components on the device chip with equal doses of electrons /10 to the 6th rad (Si)/, while the whole device was subjected to representative bias conditions. A suitable device parameter was measured in situ after each successive irradiation with the beam off.

  15. METHOD FOR OBSERVATION OF DEEMBEDDED SECTIONS OF FISH GONAD BY SCANNING ELECTRON MICROSCOPY

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This article reports a method for examining the intracellular structure of fish gonads using a scanning electron microscope(SEM). The specimen preparation procedure is similar to that for transmission electron microscopy wherein samples cut into semi-thin sections are fixed and embedded in plastic. The embedment matrix was removed by solvents. Risen-free specimens could be observed by SEM. The morphology of matured sperms in the gonad was very clear, and the oocyte internal structures appeared in three-dimensional images. Spheroidal nucleoli and yolk vesicles and several bundles of filaments adhered on the nucleoli could be viewed by SEM for the first time.

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

    Directory of Open Access Journals (Sweden)

    Suhyun Kim

    2013-09-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  18. Scanning electron microscopy and calcification in amelogenesis imperfecta in anterior and posterior human teeth

    OpenAIRE

    Sánchez-Quevedo, M. C.; Ceballos, G.; García, J. M.; Rodriguez, I. A.; Gómez de Ferraris, M. E.; Campos, Antonio

    2001-01-01

    Teeth fragments from members of a famil? 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 ...

  19. Focussed Ion Beam Milling and Scanning Electron Microscopy of Brain Tissue

    OpenAIRE

    Knott, Graham; Rosset, Stéphanie; Cantoni, Marco

    2011-01-01

    This protocol describes how biological samples, like brain tissue, can be imaged in three dimensions using the focussed ion beam/scanning electron microscope (FIB/SEM). The samples are fixed with aldehydes, heavy metal stained using osmium tetroxide and uranyl acetate. They are then dehydrated with alcohol and infiltrated with resin, which is then hardened. Using a light microscope and ultramicrotome with glass knives, a small block containing the region interest close to the surface is made....

  20. Scanning electron microscopic study of Prosorhynchoides arcuatus (Linton, 1990 (Bucephalidae: Digenea

    Directory of Open Access Journals (Sweden)

    Simone C Cohen

    1995-02-01

    Full Text Available Prosorhynchoides arcuatus (Linton, 1900 from the intestine of Pomatomus saltator (L. from the Atlantic coast of the State of Rio de Janeiro is studied by scanning electron microscopy, with detailed description of tegumental spines. Comments on the synonymy of this species with Bucephalopsis callicotyle Kohn, 1962 are made. The tegument of adult P. arcuatus presents scale like and serrated spines and uniciliated sensory papillae, distributed over the body surface and is compared with other digenetic trematodes.

  1. Solving Research Tasks Using Desk top Scanning Electron Microscope Phenom ProX

    Directory of Open Access Journals (Sweden)

    Vertsanova, O.V.

    2014-03-01

    Full Text Available Phenom ProX — morden effective universal desktop Scanning Electron Microscope with integrated EDS system. Phenom-World helps customers to stay competitive in a world where critical dimensions are continuously getting smaller. All Phenom desktop systems give direct access to the high resolution and high-quality imaging and analysis required in a large variety of applications. They are affordable, flexible and a fast tool enabling engineers, technicians, researchers and educational professionals to investigate micron and submicron structures.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  5. Effect of Autoclave Cycles on Surface Characteristics of S-File Evaluated by Scanning Electron Microscopy

    OpenAIRE

    Razavian, Hamid; Iranmanesh, Pedram; Mojtahedi, Hamid; Nazeri, Rahman

    2015-01-01

    Introduction: Presence of surface defects in endodontic instruments can lead to unwanted complications such as instrument fracture and incomplete preparation of the canal. The current study was conducted to evaluate the effect of autoclave cycles on surface characteristics of S-File by scanning electron microscopy (SEM). Methods and Materials: In this experimental study, 17 brand new S-Files (#30) were used. The surface characteristics of the files were examined in four steps (without autocla...

  6. Automatic 3D reconstruction of quasi-planar stereo Scanning Electron Microscopy (SEM) images.

    Science.gov (United States)

    Roy, S; Meunier, J; Marian, A M; Vidal, F; Brunette, I; Costantino, S

    2012-01-01

    Scanning Electron Microscopy (SEM) is widely used in science to characterize the surface roughness of materials. Three-dimensional information can be obtained with SEM based on stereovision techniques. A stereo pair is typically obtained by tilting the sample by a few degrees. In this paper we present a fully automated method for 3D reconstruction from a SEM stereo pair without any particular constraint. Results are presented for corneal stromal surfaces.

  7. Differentiation of females in Sergentomyia sensu stricto (Diptera: Psychodidae) using scanning electron microscopy of pharyngeal armatures.

    Science.gov (United States)

    Benabdennbi, I; Bombard, S; Braverman, Y; Pesson, B

    1996-03-01

    Scanning electron microscopy of external ornamentation and internal armature of the pharynx was used to identify females of Sergentomyia sensu stricto. Five species from the eastern Mediterranean basin were compared; S. minuta clearly was separated from species of the fallax-group. Within the fallax-group, S. fallax was distinguished readily by its heart-shaped pharynx and the difference in armature between the dorsal and lateral plates.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  11. Clinical and scanning electron microscopic assessments of porcelain and ceromer resin veneers.

    OpenAIRE

    Dhawan P; Prakash H; Shah N

    2003-01-01

    PURPOSE: Recently available Ceromer resin materials are promising for fabrication of esthetic anterior laminates and provices an alternative, cost effective treament modality to porcelain laminates for discolored anterior anterior teeth. It was proposed to study the esthetic quality and surface finish of veneers fbricated from ceromer resin and compare it with the standard porcelain veneers, both clinically as well as by scanning electron microscope (SEM) at baseline and at 12 months. If foun...

  12. Effect of Autoclave Cycles on Surface Characteristics of S-File Evaluated by Scanning Electron Microscopy

    OpenAIRE

    Razavian, Hamid; Iranmanesh, Pedram; Mojtahedi, Hamid; Nazeri, Rahman

    2015-01-01

    Introduction: Presence of surface defects in endodontic instruments can lead to unwanted complications such as instrument fracture and incomplete preparation of the canal. The current study was conducted to evaluate the effect of autoclave cycles on surface characteristics of S-File by scanning electron microscopy (SEM). Methods and Materials: In this experimental study, 17 brand new S-Files (#30) were used. The surface characteristics of the files were examined in four steps (without autocla...

  13. SCANNING ELECTRON MICROSCOPIC INVESTIGATION OF DENTINAL TUBULES IN MONKEY DENTIN SCANNING ELECTRON MICROSCOPIC INVESTIGATION OF DENTINAL TUBULES IN Cebus apella DENTIN

    Directory of Open Access Journals (Sweden)

    João Humberto Antoniazzi

    2009-12-01

    Full Text Available

    The aim of the study was to investigate the number and diameter of the Cebus apella dentinal tubules. The roots of the Cebus apella teeth were examined in specific tooth locations: the apical, middle and cervical dentin. The calculations were based on the scanning electron microscope photographs of the fractured surfaces. The results showed that the average number of dentinal tubules for each location was: 74,800 tubules/mm2 for apical root dentin, 90,000 tubules/mm2 for mid-root dentin, 91,600 tubules/mm2 for cervical root dentin. The average diameter was the following: apical root dentin, 4,30µm; mid-root dentin, 4,37µm; cervical root dentin,  5,23µm. These findings demonstrate that the Cebus apella teeth are a suitable substitute for human in endodontics studies. 

    KEY WORDS: Dentin, dentinal tubules, teeth.
    The aim of the study was to investigate the number and diameter of the Cebus apella dentinal tubules. The roots of the Cebus apella teeth were examined in specific tooth locations: the apical, middle and cervical dentin. The calculations were based on the scanning electron microscope photographs of the fractured surfaces. The results showed that the average number of dentinal tubules for each location was: 74,800 tubules/mm2 for apical root dentin, 90,000 tubules/mm2 for mid-root dentin, 91,600 tubules/mm2 for cervical root dentin. The average diameter was the following: apical root dentin, 4,30µm; mid-root dentin, 4,37µm; cervical root dentin,  5,23µm. These findings demonstrate that the Cebus apella teeth are a suitable substitute for human in endodontics studies. 

    KEY WORDS: Dentin, dentinal tubules, teeth.

  14. 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.

    Science.gov (United States)

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

    2017-08-01

    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. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  15. Focused ion beam (FIB)/scanning electron microscopy (SEM) in tissue structural research.

    Science.gov (United States)

    Leser, Vladka; Milani, Marziale; Tatti, Francesco; Tkalec, Ziva Pipan; Strus, Jasna; Drobne, Damjana

    2010-10-01

    The focused ion beam (FIB) and scanning electron microscope (SEM) are commonly used in material sciences for imaging and analysis of materials. Over the last decade, the combined FIB/SEM system has proven to be also applicable in the life sciences. We have examined the potential of the focused ion beam/scanning electron microscope system for the investigation of biological tissues of the model organism Porcellio scaber (Crustacea: Isopoda). Tissue from digestive glands was prepared as for conventional SEM or as for transmission electron microscopy (TEM). The samples were transferred into FIB/SEM for FIB milling and an imaging operation. FIB-milled regions were secondary electron imaged, back-scattered electron imaged, or energy dispersive X-ray (EDX) analyzed. Our results demonstrated that FIB/SEM enables simultaneous investigation of sample gross morphology, cell surface characteristics, and subsurface structures. The same FIB-exposed regions were analyzed by EDX to provide basic compositional data. When samples were prepared as for TEM, the information obtained with FIB/SEM is comparable, though at limited magnification, to that obtained from TEM. A combination of imaging, micro-manipulation, and compositional analysis appears of particular interest in the investigation of epithelial tissues, which are subjected to various endogenous and exogenous conditions affecting their structure and function. The FIB/SEM is a promising tool for an overall examination of epithelial tissue under normal, stressed, or pathological conditions.

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

    Science.gov (United States)

    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.

  17. Scanning electron microscopy and transmission electron microscopy study of hot-deformed gamma-TiAl-based alloy microstructure.

    Science.gov (United States)

    Chrapoński, J; Rodak, K

    2006-09-01

    The aim of this work was to assess the changes in the microstructure of hot-deformed specimens made of alloys containing 46-50 at.% Al, 2 at.% Cr and 2 at.% Nb (and alloying additions such as carbon and boron) with the aid of scanning electron microscopy and transmission electron microscopy techniques. After homogenization and heat treatment performed in order to make diverse lamellae thickness, the specimens were compressed at 1000 degrees C. Transmission electron microscopy examinations of specimens after the compression test revealed the presence of heavily deformed areas with a high density of dislocation. Deformation twins were also observed. Dynamically recrystallized grains were revealed. For alloys no. 2 and no. 3, the recovery and recrystallization processes were more extensive than for alloy no. 1.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  1. Scanning electron microscopic analysis of incinerated teeth: An aid to forensic identification

    Directory of Open Access Journals (Sweden)

    Chetan A Pol

    2014-01-01

    Full Text Available Background: Forensic dental identification of victims involved in fire accidents is often a complex and challenging endeavor. Knowledge of the charred human dentition and residues of restorative material can help in the recognition of bodies burned beyond recognition. Aim: To observe the effects of predetermined temperatures on healthy unrestored teeth and different restorative materials in restored teeth, by scanning electron microscope, for the purpose of identification. Materials and Methods: The study was conducted on 135 extracted teeth, which were divided into four groups. Group 1-healthy unrestored teeth, group 2-teeth restored with all ceramic crowns, group 3-teeth restored with class I composite resin and group 4-teeth restored with class I glass ionomer cement (GIC. Results: The scanning electron microscope is useful in the analysis of burned teeth, as it gives fine structural details, requires only a small sample and does not destroy the already fragile specimen. Conclusion: Scanning electron microscope can be a useful tool for the characterization and study of severely burnt teeth for victim identification.

  2. The Adsorption Geometry and Electronic Structure of Organic Dye Molecule on TiO2(101 Surface from First Principles Calculations

    Directory of Open Access Journals (Sweden)

    Niu Mang

    2017-01-01

    Full Text Available Using density functional theory (DFT, we have investigated the structural and electronic properties of dye-sensitized solar cells (DSSCs comprised of I-doped anatase TiO2(101 surface sensitized with NKX-2554 dye. The calculation results indicate that the cyanoacrylic acid anchoring group in NKX-2554 has a strong binding to the TiO2(101 surface. The dissociative and bidentate bridging type was found to be the most favorable adsorption configuration. On the other hand, the incorporations of I dopant can reduce the band gap of TiO2 photoanode and improve the of NKX-2554 dye, which can improve the visible-light absorption of anatase TiO2 and can also facilitate the electron injection from the dye molecule to the TiO2 substrate. As a result, the I doping can significantly enhance the incident photon-to-current conversion efficiency (IPCE of DSSCs.

  3. Interaction of fluorescence dyes with 5-fluorouracil: A photoinduced electron transfer study in bulk and biologically relevant water

    Science.gov (United States)

    Kuchlyan, Jagannath; Banik, Debasis; Kundu, Niloy; Roy, Arpita; Sarkar, Nilmoni

    2014-10-01

    The interactions of widely used chemotherapeutic drug, 5-fluorouracil (5FU) with coumarin dyes have been investigated for the first time using steady-state and time-resolved fluorescence spectroscopic measurements. The fluorescence quenching along with the decrease in lifetimes of excited state of coumarin derivatives with gradual addition of 5FU is explained by photoinduced electron transfer (PET) mechanism. Our studies were performed in bulk water and confined water of AOT (aerosol OT) reverse micelle to investigate the effect of confinement on PET dynamics. The feasibility of PET reaction for coumarin-5FU systems is investigated calculating the standard free energy changes using the Rehm-Weller equation.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jackman, H., E-mail: henrik.jackman@kau.se [Department of Physics and Electrical Engineering, Karlstad University, SE-651 88 Karlstad (Sweden); Krakhmalev, P. [Department of Mechanical and Materials Engineering, Karlstad University, SE-651 88 Karlstad (Sweden); Svensson, K. [Department of Physics and Electrical Engineering, Karlstad University, SE-651 88 Karlstad (Sweden)

    2013-01-15

    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. -- Highlights: Black-Right-Pointing-Pointer We model the image formation of free-standing carbon nanotubes in SEM. Black-Right-Pointing-Pointer The electron-probe shape is characterized from SEM-images. Black-Right-Pointing-Pointer We use the electron-probe shape to deconvolute SEM-images of carbon nanotubes. Black-Right-Pointing-Pointer We present a simple method for retrieval of intrinsic nanotube dimensions.

  5. Dynamic investigation of electron trapping and charge decay in electron-irradiated Al sub 2 O sub 3 in a scanning electron microscope: Methodology and mechanisms

    CERN Document Server

    Fakhfakh, S; Belhaj, M; Fakhfakh, Z; Kallel, A; Rau, E I

    2002-01-01

    The charging and discharging of polycrystalline Al sub 2 O sub 3 submitted to electron-irradiation in a scanning electron microscope (SEM) are investigated by means of the displacement current method. To circumvent experimental shortcomings inherent to the use of the basic sample holder, a redesign of the latter is proposed and tests are carried out to verify its operation. The effects of the primary beam accelerating voltage on charging, flashover and discharging phenomena during and after electron-irradiation are studied. The experimental results are then analyzed. In particular, the divergence between the experimental data and those predicted by the total electron emission yield approach (TEEYA) is discussed. A partial discharge was observed immediately after the end of the electron-irradiation exposure. The experimental data suggests, that the discharge is due to the evacuation to the ground, along the insulator surface, of released electrons from shallow traps at (or in the close vicinity of) the insulat...

  6. Facile synthesis and electron transport properties of NiO nanostructures investigated by scanning tunneling microscopy

    Directory of Open Access Journals (Sweden)

    Govind Mallick

    2017-08-01

    Full Text Available Due to their unique chemical, thermal, electronic and photonic properties, low -dimensional transition metal oxides, especially NiO, have attracted great deal of attention for potential applications in a wide range of technologies, such as, sensors, electrochromic coatings and self-healing materials. However, their synthesis involves multi-step complex procedures that in addition to being expensive, further introduce impurities. Here we present a low cost facile approach to synthesize uniform size NiO nanoparticles (NPs from hydrothermally grown Ni(OH2. Detailed transmission electron microscopic analysis reveal the average size of NiO NPs to be around 29 nm. The dimension of NiO NP is also corroborated by the small area scanning tunneling microscope (STM measurements. Further, we investigate electron transport characteristics of newly synthesized Ni(OH2 and NiO nanoparticles on p-type Si substrate using scanning tunneling microscopy. The conductivity of Ni(OH2 and NiO are determined to be 1.46x10-3 S/cm and 2.37x10-5 S/cm, respectively. The NiO NPs exhibit a lower voltage window (∼0.7 V electron tunneling than the parent Ni(OH2.

  7. Imaging three-dimensional tissue architectures by focused ion beam scanning electron microscopy.

    Science.gov (United States)

    Bushby, Andrew J; P'ng, Kenneth M Y; Young, Robert D; Pinali, Christian; Knupp, Carlo; Quantock, Andrew J

    2011-06-01

    In this protocol, we describe a 3D imaging technique known as 'volume electron microscopy' or 'focused ion beam scanning electron microscopy (FIB/SEM)' applied to biological tissues. A scanning electron microscope equipped with a focused gallium ion beam, used to sequentially mill away the sample surface, and a backscattered electron (BSE) detector, used to image the milled surfaces, generates a large series of images that can be combined into a 3D rendered image of stained and embedded biological tissue. Structural information over volumes of tens of thousands of cubic micrometers is possible, revealing complex microanatomy with subcellular resolution. Methods are presented for tissue processing, for the enhancement of contrast with osmium tetroxide/potassium ferricyanide, for BSE imaging, for the preparation and platinum deposition over a selected site in the embedded tissue block, and for sequential data collection with ion beam milling; all this takes approximately 90 h. The imaging conditions, procedures for alternate milling and data acquisition and techniques for processing and partitioning the 3D data set are also described; these processes take approxiamtely 30 h. The protocol is illustrated by application to developing chick cornea, in which cells organize collagen fibril bundles into complex, multilamellar structures essential for transparency in the mature connective tissue matrix. The techniques described could have wide application in a range of fields, including pathology, developmental biology, microstructural anatomy and regenerative medicine.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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. © 2016 Wiley Periodicals, Inc.

  11. The Probe Profile and Lateral Resolution of Scanning Transmission Electron Microscopy of Thick Specimens

    Science.gov (United States)

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

    2012-01-01

    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 the 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 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 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. PMID:22564444

  12. Chemical-state imaging of Li using scanning Auger electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, Nobuyuki, E-mail: ISHIDA.Nobuyuki@nims.go.jp [Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Fujita, Daisuke [Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Advanced Nanocharacterization Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2013-02-15

    Highlights: •Scanning Auger electron microscopy is used to image chemical states of Li. •The combined use of AES and EELS signals for the elemental mapping is powerful. •Distribution corresponding to metallic and oxidized states of Li can be imaged. -- Abstract: The demand for measurement tools to detect Li with high spatial resolution and precise chemical sensitivity is increasing with the spread of lithium-ion batteries (LIBs) for use in a wide range of applications. In this work, scanning Auger electron microscopy (SAM) is used to image chemical states of a partially oxidized Li surface on the basis of the Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS) data obtained during an oxidation process of a metal Li. We show that distribution of metallic and oxidized states of Li is clearly imaged by mapping the intensity of the corresponding AES and EELS peaks. Furthermore, a tiny difference in the extent of oxidation can be distinguished by comparing the elemental map of an AES peak with that of an EELS peak owing to the different behaviors of those signals to the chemical states of Li.

  13. Impact of particle shape on electron transport and lifetime in zinc oxide nanorod-based dye-sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Roger Chang

    2016-01-01

    Full Text Available Owing to its high electron mobility, zinc oxide represents a promising alternative to titanium dioxide as the working electrode material in dye-sensitized solar cells (DSCs. When zinc oxide is grown into 1-D nanowire arrays and incorporated into the working electrode of DSCs, enhanced electron dynamics and even a decoupling of electron transport (τd and electron lifetime (τn have been observed. In this work, DSCs with working electrodes composed of solution-grown, unarrayed ZnO nanorods are investigated. In order to determine whether such devices give rise to similar decoupling, intensity modulated photocurrent and photovoltage spectroscopies are used to measure τd and τn, while varying the illumination intensity. In addition, ZnO nanorod-based DSCs are compared with ZnO nanoparticle-based DSCs and nanomaterial shape is shown to affect electron dynamics. Nanorod-based DSCs exhibit shorter electron transport times, longer electron lifetimes, and a higher τn/τd ratio than nanoparticle-based DSCs.

  14. In situ nanomechanical testing in focused ion beam and scanning electron microscopes

    Energy Technology Data Exchange (ETDEWEB)

    Gianola, D. S. [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Institute for Applied Materials, Karlsruhe Institute of Technology, Karlsruhe (Germany); Sedlmayr, A.; Moenig, R.; Kraft, O. [Institute for Applied Materials, Karlsruhe Institute of Technology, Karlsruhe (Germany); Volkert, C. A. [Institute for Materials Physics, Georg-August University of Goettingen, Goettingen (Germany); Major, R. C.; Cyrankowski, E.; Asif, S. A. S.; Warren, O. L. [Hysitron, Inc., Minneapolis, Minnesota 55344 (United States)

    2011-06-15

    The recent interest in size-dependent deformation of micro- and nanoscale materials has paralleled both technological miniaturization and advancements in imaging and small-scale mechanical testing methods. Here we describe a quantitative in situ nanomechanical testing approach adapted to a dual-beam focused ion beam and scanning electron microscope. A transducer based on a three-plate capacitor system is used for high-fidelity force and displacement measurements. Specimen manipulation, transfer, and alignment are performed using a manipulator, independently controlled positioners, and the focused ion beam. Gripping of specimens is achieved using electron-beam assisted Pt-organic deposition. Local strain measurements are obtained using digital image correlation of electron images taken during testing. Examples showing results for tensile testing of single-crystalline metallic nanowires and compression of nanoporous Au pillars will be presented in the context of size effects on mechanical behavior and highlight some of the challenges of conducting nanomechanical testing in vacuum environments.

  15. In situ nanomechanical testing in focused ion beam and scanning electron microscopes.

    Science.gov (United States)

    Gianola, D S; Sedlmayr, A; Mönig, R; Volkert, C A; Major, R C; Cyrankowski, E; Asif, S A S; Warren, O L; Kraft, O

    2011-06-01

    The recent interest in size-dependent deformation of micro- and nanoscale materials has paralleled both technological miniaturization and advancements in imaging and small-scale mechanical testing methods. Here we describe a quantitative in situ nanomechanical testing approach adapted to a dual-beam focused ion beam and scanning electron microscope. A transducer based on a three-plate capacitor system is used for high-fidelity force and displacement measurements. Specimen manipulation, transfer, and alignment are performed using a manipulator, independently controlled positioners, and the focused ion beam. Gripping of specimens is achieved using electron-beam assisted Pt-organic deposition. Local strain measurements are obtained using digital image correlation of electron images taken during testing. Examples showing results for tensile testing of single-crystalline metallic nanowires and compression of nanoporous Au pillars will be presented in the context of size effects on mechanical behavior and highlight some of the challenges of conducting nanomechanical testing in vacuum environments.

  16. Tip alignment system in a sextupole-corrected scanning transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Ruan, S. (The Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637 (United States)); Kapp, O.H. (The Department of Radiology and The Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637 (United States))

    1993-03-01

    Tip alignment and replacement in ultrahigh vacuum field-emission electron microscopes is traditionally a time-consuming endeavor. A convenient autodrive system for the 200 kV scanning transmission electron microscope was developed to facilitate the alignment of field-emission tips, thus saving a great deal of experimenter time. Under computer control, a series of automatic electrical and mechanical processes are initiated to systematically adjust various parameters to effect passage of the electron beam through the various apertures of the microscope column. The task of finding the beam'' is thus performed automatically. In this process the tip holder is moved in a raster parallel to the first anode. Feedback from various detectors placed throughout the column direct the positioning of the tip for optimal alignment. This process is routinely performed in about 45 min.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  19. Effect of Solvent, Dye-Loading Time, and Dye Choice on the Performance of Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Fahd M. Rajab

    2016-01-01

    Full Text Available Anatase titania films with a thickness of up to 20 μm and deposited over a fluorine-doped tin-oxide substrate are impregnated with ruthenium dyes N-719 and N-749 using Dip and supercritical-fluid methods for the purpose of fabricating dye-sensitized solar cell devices. The dyes are dissolved in different solvent mixtures, including supercritical carbon dioxide, as well as combinations of more traditional solvents including mixtures of acetonitrile, and t-butanol. Analytical studies included thin-film analyzing and scanning electron microscopy to measure titania film thickness and porosity, UV-Vis spectroscopy to quantify dye concentration, and current-voltage device characterizations to assess energy conversion efficiency, as well as open-circuit voltage decay measurements and quantum efficiency to examine electron collection efficiency. A significant result is that using the dye N-749 in a solvent that includes supercritical carbon dioxide leads to energy conversion efficiencies that are higher for devices with a thick 20 μm semiconductor film than for the case of devices with thinner films, including the 10 μm film thickness that is traditionally considered an upper threshold. The supercritical-fluid method for the N-719 dye also enabled shorter impregnation duration than more conventional classical Dip Methods.

  20. A menu of electron probes for optimising information from scanning transmission electron microscopy.

    Science.gov (United States)

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

    2017-09-07

    We assess a selection of electron probes in terms of the spatial resolution with which information can be derived about the structure of a specimen, as opposed to the nominal image resolution. Using Ge [001] as a study case, we investigate the scattering dynamics of these probes and determine their relative merits in terms of two qualitative criteria: interaction volume and interpretability. This analysis provides a 'menu of probes' from which an optimum probe for tackling a given materials science question can be selected. Hollow cone, vortex and spherical wave fronts are considered, from unit cell to Ångstrom size, and for different defocus and specimen orientations. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Examination of mycological samples by means of the scanning electron microscope

    Directory of Open Access Journals (Sweden)

    M. Thibaut

    1973-04-01

    Full Text Available Three species of Siphomycetes: Rhizopus arhizus, Rhizopus equinus and Rhizopus nigricans, as well as a Septomycete: Emericella nidulans, have been examined by means of a scanning electron microscope. Among the difjerent Rhizopus, this technique showed differences in the appearance of the sporangia. In Emericella nidulans, scanning microscopy enábled one to ascertain that the "Hull cells" were completely hollow and also demonstrated the ornemented aspect of the ascospores.Três espécies de Sifomicetas: Rhizopus arhizus, Rhizopus equinus, Rhizopus nigricans e um Septomiceta: Emericella nidulans foram examinados em microscopia de exploração. Esta técnica mostrou detalhes não evidenciáveis ao poder de resolução do microscópio óptico, demonstrando ser útil para o diagnóstico em micologia.

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

    Science.gov (United States)

    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.

  3. Scanning electron microscopy study of adhesion in sea urchin blastulae. M.S. Thesis

    Science.gov (United States)

    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.

  4. Submolecular Electronic Mapping of Single Cysteine Molecules by in Situ Scanning Tunneling Imaging

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Chi, Qijin; Nazmutdinov, R. R.;

    2009-01-01

    We have used L-Cysteine (Cys) as a model system to study the surface electronic structures of single molecules at the submolecular level in aqueous buffer solution by a combination of electrochemical scanning tunneling microscopy (in situ STM), electrochemistry including voltammetry and chronocou......We have used L-Cysteine (Cys) as a model system to study the surface electronic structures of single molecules at the submolecular level in aqueous buffer solution by a combination of electrochemical scanning tunneling microscopy (in situ STM), electrochemistry including voltammetry...... and tip. The computational images recast as constant-current-height profiles show that the most favorable molecular orientation is the adsorption of cysteine as a radical in zwitterionic form located on the bridge between the Au(I 10) atomic rows and with the amine and carboxyl group toward the solution...... bulk. The correlation between physical location and electronic contrast of the adsorbed molecules was also revealed by the computational data. The present study shows that cysteine packing in the adlayer on Au(110) from the liquid environment is in contrast to that from the ultrahigh-vacuum environment...

  5. Scanning electron microscopy study of adhesion in sea urchin blastulae. M.S. Thesis

    Science.gov (United States)

    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.

  6. Large-scale Scanning Transmission Electron Microscopy (Nanotomy) of Healthy and Injured Zebrafish Brain.

    Science.gov (United States)

    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.

  7. The Role of Porphyrin-Free-Base in the Electronic Structures and Related Properties of N-Fused Carbazole-Zinc Porphyrin Dye Sensitizers

    Directory of Open Access Journals (Sweden)

    Xing-Yu Li

    2015-11-01

    Full Text Available Dye sensitizers can significantly affect power conversion efficiency of dye-sensitized solar cells (DSSCs. Porphyrin-based dyes are promising sensitizers due to their performances in DSSCs. Here, based upon a N-fused carbazole-zinc porphyrin-free-base porphyrin triad containing an ethynyl-linkage (coded as DTBC, the novel porphyrin dyes named DTBC-MP and DTBC-TP were designed by varying the porphyrin-free-base units in the π conjugation of DTBC in order to study the effect of porphyrin-free-base in the modification of electronic structures and related properties. The calculated results indicate that, the extension of the conjugate bridge with the porphyrin-free-base unit results in elevation of the highest occupied molecular orbital (HOMO energies, decrease of the lowest unoccupied molecular orbital (LUMO energies, reduction of the HOMO-LUMO gap, red-shift of the absorption bands, and enhancement of the absorbance. The free energy changes demonstrate that introducing more porphyrin-free-base units in the conjugate bridge induces a faster rate of electron injection. The transition properties and molecular orbital characters suggest that the different transition properties might lead to a different electron injection mechanism. In terms of electronic structure, absorption spectra, light harvesting capability, and free energy changes, the designed DTBC-TP is a promising candidate dye sensitizer for DSSCs.

  8. N -annulated perylene as an efficient electron donor for porphyrin-based dyes: Enhanced light-harvesting ability and high-efficiency Co(II/III)-based dye-sensitized solar cells

    KAUST Repository

    Luo, Jie

    2014-01-08

    Porphyrin-based dyes recently have become good candidates for dye-sensitized solar cells (DSCs). However, the bottleneck is how to further improve their light-harvesting ability. In this work, N-annulated perylene (NP) was used to functionalize the Zn-porphyrin, and four "push-pull"-type NP-substituted and fused porphyrin dyes with intense absorption in the visible and even in the near-infrared (NIR) region were synthesized. Co(II/III)-based DSC device characterizations revealed that dyes WW-5 and WW-6, in which an ethynylene spacer is incorporated between the NP and porphyrin core, showed pantochromatic photon-to-current conversion efficiency action spectra in the visible and NIR region, with a further red-shift of about 90 and 60 nm, respectively, compared to the benchmark molecule YD2-o-C8. As a result, the short-circuit current density was largely increased, and the devices displayed power conversion efficiencies as high as 10.3% and 10.5%, respectively, which is comparable to that of the YD2-o-C8 cell (η = 10.5%) under the same conditions. On the other hand, the dye WW-3 in which the NP unit is directly attached to the porphyrin core showed a moderate power conversion efficiency (η = 5.6%) due to the inefficient π-conjugation, and the NP-fused dye WW-4 exhibited even poorer performance due to its low-lying LUMO energy level and nondisjointed HOMO/LUMO profile. Our detailed physical measurements (optical and electrochemical), density functional theory calculations, and photovoltaic characterizations disclosed that the energy level alignment, the molecular orbital profile, and dye aggregation all played very important roles on the interface electron transfer and charge recombination kinetics. © 2013 American Chemical Society.

  9. N-annulated perylene as an efficient electron donor for porphyrin-based dyes: enhanced light-harvesting ability and high-efficiency Co(II/III)-based dye-sensitized solar cells.

    Science.gov (United States)

    Luo, Jie; Xu, Mingfei; Li, Renzhi; Huang, Kuo-Wei; Jiang, Changyun; Qi, Qingbiao; Zeng, Wangdong; Zhang, Jie; Chi, Chunyan; Wang, Peng; Wu, Jishan

    2014-01-08

    Porphyrin-based dyes recently have become good candidates for dye-sensitized solar cells (DSCs). However, the bottleneck is how to further improve their light-harvesting ability. In this work, N-annulated perylene (NP) was used to functionalize the Zn-porphyrin, and four "push-pull"-type NP-substituted and fused porphyrin dyes with intense absorption in the visible and even in the near-infrared (NIR) region were synthesized. Co(II/III)-based DSC device characterizations revealed that dyes WW-5 and WW-6, in which an ethynylene spacer is incorporated between the NP and porphyrin core, showed pantochromatic photon-to-current conversion efficiency action spectra in the visible and NIR region, with a further red-shift of about 90 and 60 nm, respectively, compared to the benchmark molecule YD2-o-C8. As a result, the short-circuit current density was largely increased, and the devices displayed power conversion efficiencies as high as 10.3% and 10.5%, respectively, which is comparable to that of the YD2-o-C8 cell (η = 10.5%) under the same conditions. On the other hand, the dye WW-3 in which the NP unit is directly attached to the porphyrin core showed a moderate power conversion efficiency (η = 5.6%) due to the inefficient π-conjugation, and the NP-fused dye WW-4 exhibited even poorer performance due to its low-lying LUMO energy level and nondisjointed HOMO/LUMO profile. Our detailed physical measurements (optical and electrochemical), density functional theory calculations, and photovoltaic characterizations disclosed that the energy level alignment, the molecular orbital profile, and dye aggregation all played very important roles on the interface electron transfer and charge recombination kinetics.

  10. A Novel Contactless Method for Characterization of Semiconductors: Surface Electron Beam Induced Voltage in Scanning Electron Microscopy

    Institute of Scientific and Technical Information of China (English)

    朱世秋; E.I.RAU; 杨富华; 郑厚植

    2002-01-01

    We present a novel contactless and nondestructive method called the surface electron beam induced voltage (SEBIV) method for characterizing semiconductor materials and devices. The SEBIV method is based on the detection of the surface potential induced by electron beams of scanning electron microscopy (SEM). The core part of the SEBIV detection set-up is a circular metal detector placed above the sample surface. The capacitance between the circular detector and whole surface of the sample is estimated to be about 0.64pf. It is large enough for the detection of the induced surface potential. The irradiation mode of electron beam (e-beam) influences the signal generation. When the e-beam irradiates on the surface of semiconductors continuously, a differential signal is obtained. The real distribution of surface potentials can be obtained when a pulsed e-beam with a fixed frequency is used for irradiation and a lock-in amplifier is employed for detection. The polarity of induced potential depends on the structure of potential barriers and surface states of samples. The contrast of SEBIV images in SEM changes with irradiation time and e-beam intensity.

  11. The design of a scan signal generator for scanning electron microscope%扫描电子显微镜的扫描电路研制

    Institute of Scientific and Technical Information of China (English)

    涂晶晶; 忻云龙; 谢东珠

    2012-01-01

    A scan signal generator for scanning electron microscope is designed based on high speed,low noise digital to analog converter. The scan rate is up to 10 pixels per second. The influence of circuit noise on image resolution is discussed. A method of correcting the current nonlinearity caused by the scanning coil inductance is presented- The developed scanning circuit has been used into the scanning electron microscope DXP - 10 and there are good images have been generated.%报导了采用高速、高精度、低噪声的数模转换器设计扫描电子显微镜的扫描电路,其扫描速率可达到每秒106像素,讨论了电路中的噪声对图像分辨率的影响,提出了一种矫正扫描线圈电感所引起的电流非线性的方法,应用到扫描电子显微镜DXP-10中,得到了较好的扫描图像.

  12. High-resolution imaging by scanning electron microscopy of semithin sections in correlation with light microscopy.

    Science.gov (United States)

    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. Atomic-Scale Study Of Complex Cobalt Oxide Using Scanning Transmission Electron Microscope

    Science.gov (United States)

    Gulec, Ahmet

    Cobalt oxides offer a rich ?eld for the formation of novel phases, including superconductors and exotic magnetic phases, involving a mixed valence state for cobalt and/or the presence of oxygen vacancies. Having spin states, such as, low spin (LS), high spin (HS), and intermediate spin (IS), cobalt oxides differ from other 3d metal oxides The presence of such spin states make the physics of the cobalt oxides so complicated that it has not yet been completely understood. In order to improve our understanding of the various phase transitions observed in Cobalt oxides and to comprehend the relationship between crystal and electronic structure, both high energy resolution and high spatial resolution are essential. Fortunately, transmission electron microscopy (TEM) is a technique which is capable of ful?lling both of these requirements. In this thesis, I have utilized unique techniques in a scanning transmission electron microscope (STEM) to analyze the atomic-scale structure-property relationship, both at room temperature and through insitu cooling to liquid nitrogen (LN2) temperature. In particular, by using correlated Z-contrast imaging, electron energy loss spectrum (EELS) and electron energy loss magnetic circular dichroism (EMCD), the structure, composition, bonding and magnetic behavior are characterized directly on the atomic scale.

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

    Science.gov (United States)

    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.

  15. Idiopathic calcinosis of the scrotum: Scanning electron microscopic study with x-ray microanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Fuezesi, L.H.; Hollweg, G.; Lagrange, W.; Mittermayer, C. (Technical Univ., Aachen (West Germany))

    1991-03-01

    In a 31-year-old man 12 nodules up to 1 cm in diameter were observed in the scrotum; these had developed over 3 years. Energy-dispersive x-ray analysis of the dermal foci showed a high content of calcium and phosphorus even in nodules smaller than 1 mm in diameter. No increased mineral deposition was observed in the surrounding connective tissue, however. Scanning electron microscopy revealed finely granulated crystals, and cellular remnants giving rise to development of calcified nodules were disclosed. The results support the hypothesis of a degenerative origin of scrotal calcinosis.

  16. Scanning electron microscopy of a blister roof in dystrophic epidermolysis bullosa*

    Science.gov (United States)

    de Almeida Jr., Hiram Larangeira; Monteiro, Luciane; Silva, Ricardo Marques e; 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. PMID:24474107

  17. Scanning electron microscopy of a blister roof in dystrophic epidermolysis bullosa.

    Science.gov (United States)

    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.

  18. Scanning electron microscopy of the collodion membrane from a self-healing collodion baby*

    Science.gov (United States)

    de Almeida Jr., Hiram Larangeira; Isaacsson, Henrique; Guarenti, Isabelle Maffei; Silva, Ricardo Marques e; de Castro, Luis Antônio Suita

    2015-01-01

    Abstract Self-healing collodion baby is a well-established subtype of this condition. We examined a male newborn, who was covered by a collodion membrane. The shed membrane was examined with scanning electron microscopy. The outer surface showed a very compact keratin without the normal elimination of corneocytes. The lateral view of the specimen revealed a very thick, horny layer. The inner surface showed the structure of lower corneocytes with polygonal contour. With higher magnifications villous projections were seen in the cell membrane. PMID:26375232

  19. A scanning electron microscopic study of impala (Aepyceros melampus sperm from the Kruger National Park

    Directory of Open Access Journals (Sweden)

    D.J. Ackerman

    1996-02-01

    Full Text Available Since knowledge of sperm morphological characteristics can play an important role in semen evaluation and fertilisation, baseline data on sperm ultrastructure are required. Live spermatozoa were collected from the cauda epididymis from 64 impala rams in the Kruger National Park and 5082 spermatozoa from 40 of these impala were studied by scanning electron microscopy. The mean length of impala sperm was 59.23 @ 2.7 um. The morphology of normal sperm as well as the occurrence of abnormalities were documented. The morphology of impala sperm were compared with those of other mammals. New findings on appendages of the cytoplasmic droplet are described and interpreted.

  20. Scanning electron microscopy and X-ray spectroscopy applied to mycelial phase of sporothrix schenckii

    Directory of Open Access Journals (Sweden)

    M. Thibaut

    1975-04-01

    Full Text Available Scanning electron microscopy applied to the mycelial phase of Sporothrix schenckii shows a matted mycelium with conidia of a regular pattern. X-Ray microanalysis applied in energy dispersive spectroscopy and also in wavelength dispersive spectroscopy reveals the presence of several elements of Mendeleef's classification.Sporothrix schenckii foi estudado em microscopia eletrônica. Foram observados caracteres das hífas e dos esporos, vários elementos da classificação periódica foram postos em evidência graças à micro-análise a raios X.

  1. In situ scanning tunnelling microscopy of redox molecules. Coherent electron transfer at large bias voltages

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Kuznetsov, A.M.; Ulstrup, Jens

    2003-01-01

    Theories of in situ scanning tunnelling microscopy (STM) of molecules with redox levels near the substrate and tip Fermi levels point to 'spectroscopic' current-overpotential features. Prominent features require a narrow 'probing tip', i.e. a small bias voltage, eV(bias), compared...... and tip Fermi levels. STM here involves coherent two-step interfacial electron transfer between the redox level and the enclosing substrate and tip. We have also extended previous experimental in situ STM studies of the blue copper protein Pseudomonas aeruginosa azurin, adsorbed on Au(111), to cover...

  2. Lanthanum Deposition in the Stomach: Usefulness of Scanning Electron Microscopy for Its Detection.

    Science.gov (United States)

    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.

  3. Scanning transmission electron microscopy analysis of grain structure in perpendicular magnetic recording media.

    Science.gov (United States)

    Hossein-Babaei, Faraz; Sinclair, Robert; Sinclair, Robert A; Srinivasan, Kumar; Bertero, Gerardo A

    2011-09-14

    The key component of a hard disk medium is a Co-based magnetic layer (ML) grown on a Ru seed layer. The ML nanostructure, composed of less than 10 nm grains, is believed to be controlled by this seed layer. We successfully used scanning transmission electron microscopy energy dispersive spectrometry simultaneous composition-based imaging and Moiré pattern analysis for determining the mutual structural and orientation relationship between the two layers revealing a grain-to-grain agreement. The method presented here can be utilized for observing structural correlations between consecutive polycrystalline thin film layers in general.

  4. Dynamics of annular bright field imaging in scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Findlay, S.D., E-mail: scott@sigma.t.u-tokyo.ac.jp [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); Shibata, N. [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); PRESTO, Japan Science and Technology Agency, Saitama 332-0012 (Japan); Sawada, H.; Okunishi, E.; Kondo, Y. [JEOL Ltd., Tokyo 196-8558 (Japan); Ikuhara, Y. [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587 (Japan); WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2010-06-15

    We explore the dynamics of image formation in the so-called annular bright field mode in scanning transmission electron microscopy, whereby an annular detector is used with detector collection range lying within the cone of illumination, i.e. the bright field region. We show that this imaging mode allows us to reliably image both light and heavy columns over a range of thickness and defocus values, and we explain the contrast mechanisms involved. The role of probe and detector aperture sizes is considered, as is the sensitivity of the method to intercolumn spacing and local disorder.

  5. Scanning electron microscopy with polarization analysis for multilayered chiral spin textures

    Science.gov (United States)

    Lucassen, Juriaan; Kloodt-Twesten, Fabian; Frömter, Robert; Oepen, Hans Peter; Duine, Rembert A.; Swagten, Henk J. M.; Koopmans, Bert; Lavrijsen, Reinoud

    2017-09-01

    We show that scanning electron microscopy with polarization analysis (SEMPA) that is sensitive to both in-plane magnetization components can be used to image the out-of-plane magnetized multi-domain state in multilayered chiral spin textures. By depositing a thin layer of Fe on top of the multilayer, we image the underlying out-of-plane domain state through the mapping of its stray fields in the Fe. We also demonstrate that SEMPA can be used to image the domain wall chirality in these systems after milling away the capping layer and imaging the topmost magnetic layer directly.

  6. 3D scanning electron microscopy applied to surface characterization of fluorosed dental enamel.

    Science.gov (United States)

    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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Compositional analysis of GaAs/AlGaAs heterostructures using quantitative scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kauko, H.; Helvoort, A. T. J. van [Department of Physics, Norwegian University of Science and Technology (NTNU), Trondheim (Norway); Zheng, C. L.; Glanvill, S. [Monash Centre for Electron Microscopy, Monash University, VIC 3800 (Australia); Zhu, Y.; Etheridge, J., E-mail: joanne.etheridge@monash.edu [Monash Centre for Electron Microscopy, Monash University, VIC 3800 (Australia); Department of Materials Engineering, Monash University, VIC 3800 (Australia); Dwyer, C. [Monash Centre for Electron Microscopy, Monash University, VIC 3800 (Australia); Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Munshi, A. M.; Fimland, B. O. [Department of Electronics and Telecommunications, Norwegian University of Science and Technology (NTNU), Trondheim (Norway)

    2013-12-02

    We demonstrate a method for compositional mapping of Al{sub x}Ga{sub 1–x}As heterostructures with high accuracy and unit cell spatial resolution using quantitative high angle annular dark field scanning transmission electron microscopy. The method is low dose relative to spectroscopic methods and insensitive to the effective source size and higher order lens aberrations. We apply the method to study the spatial variation in Al concentration in cross-sectioned GaAs/AlGaAs core-shell nanowires and quantify the concentration in the Al-rich radial band and the AlGaAs shell segments.

  8. Scanning electron microscopy of larval instars and imago of Oestrus caucasicus (Grunin, 1948 (Diptera: Oestridae

    Directory of Open Access Journals (Sweden)

    Guitton C.

    2001-06-01

    Full Text Available Oestrus caucasicus (Grunin, 1948 is a larval parasite of the nasal cavities of Capra caucasica, Capra ibex and Capra pyrenaica. This study is the first description of the parasite using scanning electron microscopy. The first larval instar shows minor differences with Oestrus ovis. The second larval instar shows important synapomorphic features common to Oestrus ovis but, also, distinctive features as the spines-crown or the currycomb-shaped spines. The third larval instar shows many differences with Oestrus ovis, mostly in the ventral and dorsal spines. The imagos of the two species have closely related morphologies. This study is a contribution to a revision of phylogeny of Oestridae family.

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

    OpenAIRE

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

    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 visualis...

  10. Carbon-fiber tips for scanning probe microscopes and molecular electronics experiments.

    Science.gov (United States)

    Rubio-Bollinger, Gabino; Castellanos-Gomez, Andres; Bilan, Stefan; Zotti, Linda A; Arroyo, Carlos R; Agraït, Nicolás; Cuevas, Juan Carlos

    2012-05-15

    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.

  11. Fatal poisoning by Rumex crispus (curled dock): pathological findings and application of scanning electron microscopy.

    Science.gov (United States)

    Reig, R; Sanz, P; Blanche, C; Fontarnau, R; Dominguez, A; Corbella, J

    1990-10-01

    A case of fatal poisoning due to ingestion of the plant Rumex crispus (curled dock) is described. The patient, a 53-year-old male, presented with gastrointestinal symptoms, severe hypocalcemia, metabolic acidosis and acute hepatic insufficiency. Despite therapeutic measures, the patient died 72 h after ingestion of the plant material. Noteworthy among the pathological findings were centrolobular hepatic necrosis and birefringent crystals in the liver and kidneys that were identified by histochemical techniques and scanning electron microscopy. These observations are compared with other reports in the medical literature, with an emphasis on the risk involved in the use of these plants for culinary or medicinal purposes.

  12. Investigations of a Cretaceous limestone with spectral induced polarization and scanning electron microscopy

    DEFF Research Database (Denmark)

    Johansson, Sara; Sparrembom, Charlotte; Fiandaca, Gianluca

    2017-01-01

    in early time ranges for bedrock characterization. The inverted sections showed variations within the limestone that could be caused by variations in texture and composition. Samples from a deep drilling in the Kristianstad basin were investigated with scanning electron microscopy and energy dispersive X...... in the texture of the limestone at different levels, governed by fossil shapes and composition, proportions of calcareous cement and matrix as well as amount of silicate grains. Textural variations may have implications on the variation in Cole–Cole relaxation time and frequency factor. However, more research...

  13. Scanning electron microscopy study of protein immobilized on SIO2 Sol-gel surfaces

    Directory of Open Access Journals (Sweden)

    O.B.G. Assis

    2003-09-01

    Full Text Available Uniform attachment of enzymes to solid surfaces is essential in the development of bio and optical sensor devices. Immobilization by adsorption according to hydrophilic or hydrophobic nature is dependent on the charges and defects of the support surfaces. Sol-gel SiO2 densified glass surfaces, frequently used as supports for protein immobilization, are evaluated via scanning electron microscopy. The model protein is globular enzyme lysozyme, deposited by adsorption on functionalized surfaces. Formation of a protein layer is confirmed by FTIR spectroscopy, and the SEM images suggest discontinuous adsorption in areas where cracks predominate on the glass surface.

  14. Environmental scanning electron microscope (ESEM) evaluation of crystal and plaque formation associated with biocorrosion.

    Science.gov (United States)

    Geiger, S L; Ross, T J; Barton, L L

    1993-08-01

    The biofilm attributed to Desulfovibrio vulgaris growing in the presence of ferrous metals was examined with an environmental scanning electron microscope. This novel microscope produced images of iron sulfide colloids and other iron containing structures that had not been reported previously. A plaque composed of iron sulfide enveloped the surface of the corroding metal while crystals containing magnesium, iron, sulfur, and phosphorus were present in the culture where corrosion was in progress. A structure resembling the tubercule found in aerobic corrosion was observed on stainless steel undergoing biocorrosion and the elements present in this structure included sulfur, iron, chloride, calcium, potassium, and chromium.

  15. Light and scanning electron microscopic investigations on MiteStop-treated poultry red mites.

    Science.gov (United States)

    Locher, Nina; Klimpel, Sven; Abdel-Ghaffar, Fathy; Al Rasheid, Khaled A S; Mehlhorn, Heinz

    2010-07-01

    Recent studies of the neem seed product MiteStop showed that it has a good acaricidal effect against all developmental stages of the poultry red mite, Dermanyssus gallinae. In vitro tests proved an efficacy at direct contact, as well as by fumigant toxicity. Light and scanning electron microscopic (SEM) investigations showed no clear, morphologically visible signs of an effect caused by fumigant toxicity. Direct contact with the neem product, however, seemed to be of great impact. Chicken mites turned dark brown or even black after being treated with the neem product. SEM analysis showed damages along the body surface of the mites.

  16. Morphological studies of Gross virus-induced lymphoblasts by scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Ichikawa,Hiroyuki

    1977-04-01

    Full Text Available The surface of Gross virus-induced murine lymphoblasts and C-type virus particles budding from these cells were investigated under the scanning electron microscope (SEM. The cells appeared spindle-shaped or roughly-rounded with extensive surface features consisting of microvilli, blebs and ruffled membranes. C-type virus particles were detected on the cell membrane as small spherical particles, distinguishable from the microvilli. Clustered virions were observed in some cases. However, the distribution of virions appeared to be random. The surface of the virion was smooth and had no globular units at high magnification. These morphological observations were confirmed in ultrathin sections.

  17. Dye removal using modified copper ferrite nanoparticle and RSM analysis.

    Science.gov (United States)

    Mahmoodi, Niyaz Mohammad; Soltani-Gordefaramarzi, Sajjad; Sadeghi-Kiakhani, Moosa

    2013-12-01

    In this paper, copper ferrite nanoparticle (CFN) was synthesized, modified by cetyl trimethylammonium bromide, and characterized. Dye removal ability of the surface modified copper ferrite nanoparticle (SMCFN) from single system was investigated. The physical characteristics of SMCFN were studied using Fourier transform infrared, scanning electron microscopy, and X-ray diffraction. Acid Blue 92, Direct Green 6, Direct Red 23, and Direct Red 80 were used as model compounds. The effect of operational parameters (surfactant concentration, adsorbent dosage, dye concentration, and pH) on dye removal was evaluated. Response surface methodology (RSM) was used for the analysis of the dye removal data. The experimental checking in these optimal conditions confirms good agreements with RSM results. The results showed that the SMCFN being a magnetic adsorbent might be a suitable alternative to remove dyes from colored aqueous solutions.

  18. Spectroscopic, DFT and Z-scan supported investigation of dicyanoisophorone based push-pull NLOphoric styryl dyes

    Science.gov (United States)

    Erande, Yogesh; Sreenath, Mavila C.; Chitrambalam, Subramaniyan; Joe, Isaac H.; Sekar, Nagaiyan

    2017-04-01

    The dicyanoisophorone acceptor based NLOphores with Intramolecular Charge Transfer (ICT) character are newly synthesised, characterised and explored for linear and non linear optical (NLO) property investigation. Strong ICT character of these D-π-A styryl NLOphores is established with support of emission solvatochromism, polarity functions and Generalised Mulliken Hush (GMH) analysis. First, second and third order polarizability of these NLOphores is investigated by spectroscopic and TDDFT computational approach using CAM/B3LYP-6-311 + g (d, p) method. BLA and BOA values of these chromophores are evaluated from ground and excited state optimized geometries and found that the respective structures are approaching towards cyanine limit. Third order nonlinear susceptibility (X(3)/SUP>) along with nonlinear absorption coefficient (β) and nonlinear refraction (n2) are evaluated for these NLOphores using Z-scan experiment. All four chromophores exhibit large polarization anisotropy (Δα), first order hyperpolarizability (β0), second order hyperpolarizability (γ) and third order nonlinear susceptibility (X(3)/SUP>). TGA analysis proved these NLOphores are stable up to 320 °C and hence can be used in device fabrication.

  19. Correlating excited state and charge carrier dynamics with photovoltaic parameters of perylene dye sensitized solar cells: influences of an alkylated carbazole ancillary electron-donor.

    Science.gov (United States)

    Li, Yang; Wang, Junting; Yuan, Yi; Zhang, Min; Dong, Xiandui; Wang, Peng

    2017-01-18

    Two perylene dyes characteristic of electron-donors phenanthrocarbazole (PC) and carbazyl functionalized PC are selected to study the complicated dynamics of excited states and charge carriers, which underlie the photovoltaic parameters of dye-sensitized solar cells (DSCs). We have combined femtosecond fluorescence up-conversion and time-resolved single-photon counting techniques to probe the wavelength-dependent photoluminescence dynamics of dye molecules not only dissolved in THF but also grafted on the surface of oxide nanoparticles. Excited state relaxation and electron injection both occur on a similar timescale, resulting in a very distributive kinetics of electron injection. It is also found that the carbazyl ancillary electron-donor causes a faster electron injection, which over-compensates the adverse impact of a slightly shorter lifetime of the equilibrium excited state. Nanosecond transient absorption and transient photovoltage decay measurements have shown that conjugating carbazyl to PC can effectively slow down the kinetics of charge recombination of electrons in titania with both photo-oxidized dye molecules and triiodide anions, improving the cell photovoltage.

  20. Ab initio calculation of the electronic spectrum of azobenzene dyes and its impact on the design of optical data storage materials

    DEFF Research Database (Denmark)

    Åstrand, Per-Olof; Ramanujam, P.S.; Hvilsted, Søren

    2000-01-01

    Electronic excitation energies of 16 azobenzene dyes have been calculated by ab initio methods within the second-order polarization propagator approximation (SOPPA). Good agreement with expriment is found for the lowest singlet and triplet states for both the trans- and cis-azobenzene molecules......, the experimental singlet π → π* transitions are reproduced for a set of azobenzene dyes with different electron donor and acceptor groups and the correct shifts in excitation energy are obtained for the different substituents. It has also been demonstrated that ab initio methods can be used to determine suitable...... candidates for azo components used in materials for data storage....

  1. Scanning transmission electron microscopic tomography of cortical bone using Z-contrast imaging.

    Science.gov (United States)

    McNally, Elizabeth; Nan, Feihong; Botton, Gianluigi A; Schwarcz, Henry P

    2013-06-01

    Previously we presented (McNally et al., 2012) a model for the ultrastructure of bone showing that the mineral resides principally outside collagen fibrils in the form of 5 nm thick mineral structures hundreds of nanometers long oriented parallel to the fibrils. Here we use high-angle annular dark-field electron tomography in the scanning transmission electron microscope to confirm this model and further elucidate the composite structure. Views of a section cut parallel to the fibril axes show bundles of mineral structures extending parallel to the fibrils and encircling them. The mineral density inside the fibrils is too low to be visualized in these tomographic images. A section cut perpendicular to the fibril axes, shows quasi-circular walls composed of mineral structures, wrapping around apparently empty holes marking the sites of fibrils. These images confirm our original model that the majority of mineral in bone resides outside the collagen fibrils.

  2. Scanning tunneling microscopy characterization of the geometric and electronic structure of hydrogen-terminated silicon surfaces

    Science.gov (United States)

    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.

  3. Biological application of Compressed Sensing Tomography in the Scanning Electron Microscope

    Science.gov (United States)

    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

  4. Scanning electron microscope cathodoluminescence imaging of subgrain boundaries, twins and planar deformation features in quartz

    Science.gov (United States)

    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.

  5. Segmentation of scanning electron microscopy images from natural rubber samples with gold nanoparticles using starlet wavelets.

    Science.gov (United States)

    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.

  6. Microtubule organization within mitotic spindles revealed by serial block face scanning electron microscopy and image analysis.

    Science.gov (United States)

    Nixon, Faye M; Honnor, Thomas R; Clarke, Nicholas I; Starling, Georgina P; Beckett, Alison J; Johansen, Adam M; Brettschneider, Julia A; Prior, Ian A; Royle, Stephen J

    2017-05-15

    Serial block face scanning electron microscopy (SBF-SEM) is a powerful method to analyze cells in 3D. Here, working at the resolution limit of the method, we describe a correlative light-SBF-SEM workflow to resolve microtubules of the mitotic spindle in human cells. We present four examples of uses for this workflow that are not practical by light microscopy and/or transmission electron microscopy. First, distinguishing closely associated microtubules within K-fibers; second, resolving bridging fibers in the mitotic spindle; third, visualizing membranes in mitotic cells, relative to the spindle apparatus; and fourth, volumetric analysis of kinetochores. Our workflow also includes new computational tools for exploring the spatial arrangement of microtubules within the mitotic spindle. We use these tools to show that microtubule order in mitotic spindles is sensitive to the level of TACC3 on the spindle. © 2017. Published by The Company of Biologists Ltd.

  7. Formation of Three-Way Scanning Electron Microscope Moiré on Micro/Nanostructures

    Directory of Open Access Journals (Sweden)

    Qinghua Wang

    2014-01-01

    Full Text Available Three-way scanning electron microscope (SEM moiré was first generated using a designed three-way electron beam (EB in an SEM. The spot-type three-way SEM moiré comes from the interference between the three-way EB and the specimen grating in which the periodic cells are arranged in a triangular manner. The deformation and the structure information of the specimen grating in three directions can be simultaneously obtained from the three-way SEM moiré. The design considerations of the three-way EB were discussed. As an illustration, the three-way SEM moiré spots produced on a silicon slide were presented. The proposed three-way SEM moiré method is expected to characterize micro/nanostructures in triangular or hexagonal arrangements in three directions at the same time.

  8. High contrast en bloc staining of neuronal tissue for field emission scanning electron microscopy

    Science.gov (United States)

    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

  9. Electron transport parameters in CO$_2$: scanning drift tube measurements and kinetic computations

    CERN Document Server

    Vass, M; Loffhagen, D; Pinhao, N; Donko, Z

    2016-01-01

    This work presents transport coefficients of electrons (bulk drift velocity, longitudinal diffusion coefficient, and effective ionization frequency) in CO2 measured under time-of-flight conditions over a wide range of the reduced electric field, 15Td <= E/N <= 2660Td in a scanning drift tube apparatus. The data obtained in the experiments are also applied to determine the effective steady-state Townsend ionization coefficient. These parameters are compared to the results of previous experimental studies, as well as to results of various kinetic computations: solutions of the electron Boltzmann equation under different approximations (multiterm and density gradient expansions) and Monte Carlo simulations. The experimental data extend the range of E/N compared with previous measurements and are consistent with most of the transport parameters obtained in these earlier studies. The computational results point out the range of applicability of the respective approaches to determine the different measured tr...

  10. Scanning-electron-microscopy observations and mechanical characteristics of ion-beam-sputtered surgical implant alloys

    Science.gov (United States)

    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.

  11. Prospects for lithium imaging using annular bright field scanning transmission electron microscopy: A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Findlay, S.D., E-mail: scott@sigma.t.u-tokyo.ac.jp [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); Lugg, N.R. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Shibata, N. [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); PRESTO, Japan Science and Technology Agency, Saitama 332-0012 (Japan); Allen, L.J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Ikuhara, Y. [Institute of Engineering Innovation, The University of Tokyo, Tokyo 116-0013 (Japan); Nanostructures Research Laboratory, Japan Fine Ceramic Center, Nagoya 456-8587 (Japan); WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2011-07-15

    There is strong interest in lithium imaging, particularly because of its significance in battery materials. However, light atoms only scatter electrons weakly and atomic resolution direct imaging of lithium has proven difficult. This paper explores theoretically the conditions under which lithium columns can be expected to be directly visible using annular bright field scanning transmission electron microscopy. A detailed discussion is given of the controllable parameters and the conditions most favourable for lithium imaging. -- Highlights: {yields} Optimum conditions to image Li columns in Li-bearing materials with ABF are explored. {yields} Higher accelerating voltages give better contrast at a given resolution. {yields} Aperture size must compromise between resolution and good coupling to the column. {yields} Samples with small along-column interatomic spacing between Li atoms are best. {yields} The trends observed are consistent with prediction based on the s-state model.

  12. 4D scanning transmission ultrafast electron microscopy: Single-particle imaging and spectroscopy.

    Science.gov (United States)

    Ortalan, Volkan; Zewail, Ahmed H

    2011-07-20

    We report the development of 4D scanning transmission ultrafast electron microscopy (ST-UEM). The method was demonstrated in the imaging of silver nanowires and gold nanoparticles. For the wire, the mechanical motion and shape morphological dynamics were imaged, and from the images we obtained the resonance frequency and the dephasing time of the motion. Moreover, we demonstrate here the simultaneous acquisition of dark-field images and electron energy loss spectra from a single gold nanoparticle, which is not possible with conventional methods. The local probing capabilities of ST-UEM open new avenues for probing dynamic processes, from single isolated to embedded nanostructures, without being affected by the heterogeneous processes of ensemble-averaged dynamics. Such methodology promises to have wide-ranging applications in materials science and in single-particle biological imaging.

  13. Thermal Evolution of Organic Matter in Source Rocks—Experimental and Scanning Electron Microscopic Studies

    Institute of Scientific and Technical Information of China (English)

    姜开侠; 潘小明

    1991-01-01

    Five major froms(lamellar,banded,crack-like,dissceminated and segregated encrustation(of organic matter distribution in sourc rocks have been revealed under scanning electron microscope by using the heavy metal staining technique.The degree of organic impregnation is related to the amount of liquied hydrocarbons in the rocks,and from this relationship a rough estimation of organic matter can be made on the basis of electron microscopic observations.In conjunction with experimental studies it has been found that the distribution forms of organic matter are a function of its maturity in the process of thermal evolution and accordingly some microscopic criteria can be developed for the assessment of source rocks.

  14. Fabrication of gradient material by electron beam smelting based on scanning track control

    Institute of Scientific and Technical Information of China (English)

    YANG Shanglei; XUE Xiaohuai; LOU Songnian; LU Fenggui

    2007-01-01

    A new electron beam (EB) control system was developed in a general vacuum EB machine by equipping it with an industrial control computer, programmable logic control (PLC), deflection coil, data acquisition card, power amplifier, etc. In this control system, the scanning track and energy distribution of the EB could be edited off-line,adjusted in real-time, and controlled on-line. Ti-Mo gradient material (GM) with high temperature resistance was fabri-cated using electron beam smelting (EBS) control. The smelting processes include three steps such as preheating,smelting, and homogenizing. The results show that GM pre-pared by using smelting technology has fine appearance, and has good integrated interface with Ti alloy. The Mo and Ti elements are gradual diversification in the interface of the gradient material. The microstructure near the Ti alloy base metal is α + β basket-waver grain, and the microstructure near GM is single phase of β solid solution.

  15. Compact device for cleaning scanner-mounted scanning tunneling microscope tips using electron bombardment

    Science.gov (United States)

    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.

  16. A new method for measurement of the vitrification rate of earthenware texture by scanning electron microscope.

    Science.gov (United States)

    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.

  17. Clinical applications of scanning electron microscopy and X-ray microanalysis in dermatology

    Energy Technology Data Exchange (ETDEWEB)

    Forslind, B.

    1984-01-01

    Scanning electron microscopy is frequently applied to dermatological problems, as is evident from a review of the recent literature. In this paper, preparation methods and new techniques allowing experimental studies on the integumentary system are emphasized. Quantitative analysis in the electron microscope by use of energy-dispersive X-ray microanalysis (EDX) has become an important accessory technique. EDX can, for instance, be used to study problems involving physiological changes induced in skin by agents causing contact reactions. Recently, it has been shown that treatment with DNCB, chromate and nickel causes changes in elemental distribution in guinea-pig skin. In addition, elemental uptake in the integumentary system and in pathological inclusions in skin can be analyzed.

  18. Modification of a Scanning Tunneling Microscope for Measurement of Ballistic Electron Emission Microscopy

    Science.gov (United States)

    Hsieh, Satcher; Hong, Jeongmin; Bokor, Jeffrey

    2014-03-01

    Magnetic memory and logic devices show great promise for integration with, and even replacement of, conventional complementary metal-oxide-semiconductor (CMOS) architectures. In order to characterize materials and deposition techniques for these devices, ballistic electron emission microscopy (BEEM) is used. BEEM is a spatially resolved metrological tool most commonly used for subsurface interface structures at the nanometer scale. We modify a scanning tunneling microscope (STM) to perform BEEM measurement via design and fabrication of a novel sample stage. Furthermore, we design and fabricate an external magnetic field source that encapsulates the sample stage, setting the foundation for future measurement of ballistic electron magnetic microscopy (BEMM). Instrumentation of the device and characterization of a sample with an ohmic interface, Ni-Si, are implemented and discussed. With support from National Science Foundation Award ECCS-0939514.

  19. Structure Prediction of Self-Assembled Dye Aggregates from Cryogenic Transmission Electron Microscopy, Molecular Mechanics, and Theory of Optical Spectra.

    Science.gov (United States)

    Friedl, Christian; Renger, Thomas; Berlepsch, Hans V; Ludwig, Kai; Schmidt Am Busch, Marcel; Megow, Jörg

    2016-09-01

    Cryogenic transmission electron microscopy (cryo-TEM) studies suggest that TTBC molecules self-assemble in aqueous solution to form single-walled tubes with a diameter of about 35 Å. In order to reveal the arrangement and mutual orientations of the individual molecules in the tube, we combine information from crystal structure data of this dye with a calculation of linear absorbance and linear dichroism spectra and molecular dynamics simulations. We start with wrapping crystal planes in different directions to obtain tubes of suitable diameter. This set of tube models is evaluated by comparing the resulting optical spectra with experimental data. The tubes that can explain the spectra are investigated further by molecular dynamics simulations, including explicit solvent molecules. From the trajectories of the most stable tube models, the short-range ordering of the dye molecules is extracted and the optimization of the structure is iteratively completed. The final structural model is a tube of rings with 6-fold rotational symmetry, where neighboring rings are rotated by 30° and the transition dipole moments of the chromophores form an angle of 74° with respect to the symmetry axis of the tube. This model is in agreement with cryo-TEM images and can explain the optical spectra, consisting of a sharp red-shifted J-band that is polarized parallel to to the symmetry axis of the tube and a broad blue-shifted H-band polarized perpendicular to this axis. The general structure of the homogeneous spectrum of this hybrid HJ-aggregate is described by an analytical model that explains the difference in redistribution of oscillator strength inside the vibrational manifolds of the J- and H-bands and the relative intensities and excitation energies of those bands. In addition to the particular system investigated here, the present methodology can be expected to aid the structure prediction for a wide range of self-assembled dye aggregates.

  20. The ultrastructure of pollen grain surface in allotetraploid petunia (Petunia hybrida hort. superbissima as revealed by scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    S. Muszyński

    2015-05-01

    Full Text Available The ultrastructure of pollen grain surface in allotetraploid petunias was analyzed by scanning electron microscopy. The pollen grain wall is developed into characteristic pattern of convulations.

  1. The surface topography of the choroid plexus. Environmental, low and high vacuum scanning electron microscopy.

    Science.gov (United States)

    Mestres, Pedro; Pütz, Norbert; Garcia Gómez de Las Heras, Soledad; García Poblete, Eduardo; Morguet, Andrea; Laue, Michael

    2011-05-01

    Environmental scanning electron microscopy (ESEM) allows the examination of hydrated and dried specimens without a conductive metal coating which could be advantageous in the imaging of biological and medical objects. The aim of this study was to assess the performance and benefits of wet-mode and low vacuum ESEM in comparison to high vacuum scanning electron microscopy (SEM) using the choroid plexus of chicken embryos as a model, an organ of the brain involved in the formation of cerebrospinal fluid in vertebrates. Specimens were fixed with or without heavy metals and examined directly or after critical point drying with or without metal coating. For wet mode ESEM freshly excised specimens without any pre-treatment were also examined. Conventional high vacuum SEM revealed the characteristic morphology of the choroid plexus cells at a high resolution and served as reference. With low vacuum ESEM of dried but uncoated samples the structure appeared well preserved but charging was a problem. It could be reduced by a short beam dwell time and averaging of images or by using the backscattered electron detector instead of the gaseous secondary electron detector. However, resolution was lower than with conventional SEM. Wet mode imaging was only possible with tissue that had been stabilized by fixation. Not all surface details (e.g. microvilli) could be visualized and other structures, like the cilia, were deformed. In summary, ESEM is an additional option for the imaging of bio-medical samples but it is problematic with regard to resolution and sample stability during imaging. Copyright © 2011 Elsevier GmbH. All rights reserved.

  2. Investigating the use of in situ liquid cell scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nguy, Amanda [Iowa State Univ., Ames, IA (United States)

    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

  3. Evaluation of gas chromatography – electron ionization – full scan high resolution Orbitrap mass spectrometry for pesticide residue analysis

    NARCIS (Netherlands)

    Mol, Hans G.J.; Tienstra, Marc; Zomer, Paul

    2016-01-01

    Gas chromatography with electron ionization and full scan high resolution mass spectrometry with an Orbitrap mass analyzer (GC-EI-full scan Orbitrap HRMS) was evaluated for residue analysis. Pesticides in fruit and vegetables were taken as an example application. The relevant aspects for GC-MS

  4. Electronic optimization of heteroleptic Ru(II) bipyridine complexes by remote substituents: synthesis, characterization, and application to dye-sensitized solar cells.

    Science.gov (United States)

    Han, Won-Sik; Han, Jung-Kyu; Kim, Hyun-Young; Choi, Mi Jin; Kang, Yong-Soo; Pac, Chyongjin; Kang, Sang Ook

    2011-04-18

    We prepared a series of new heteroleptic ruthenium(II) complexes, Ru(NCS)(2)LL' (3a-3e), where L is 4,4'-di(hydroxycarbonyl)-2,2'-bipyridine and L' is 4,4'-di(p-X-phenyl)-2,2'-pyridine (X = CN (a), F (b), H (c), OMe (d), and NMe(2) (e)), in an attempt to explore the structure-activity relationships in their photophysical and electrochemical behavior and in their performance in dye-sensitized solar cells (DSSCs). When substituent X is changed from electron-donating NMe(2) to electron-withdrawing CN, the absorption and emission maxima reveal systematic bathochromic shifts. The redox potentials of these dyes are also significantly influenced by X. The electronic properties of the dyes were theoretically analyzed using density functional theory calculations; the results show good correlations with the experimental results. The solar-cell performance of DSSCs based on dye-grafted nanocrystalline TiO(2) using 3a-3e and standard N3 (bis[(4,4'-carboxy-2,2'-bipyridine)(thiocyanato)]ruthenium(II)) were compared, revealing substantial dependences on the dye structures, particularly on the remote substituent X. The 3d-based device showed the best performance: η = 8.30%, J(SC) = 16.0 mA·cm(-2), V(OC) = 717 mV, and ff = 0.72. These values are better than N3-based device.

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

    Science.gov (United States)

    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.

  6. Analysis of acute impact of oleoresin capsicum on rat nasal mucosa using scanning electron microscopy.

    Science.gov (United States)

    Catli, Tolgahan; Acar, Mustafa; Olgun, Yüksel; Dağ, İlknur; Cengiz, Betül Peker; Cingi, Cemal

    2015-01-01

    Analysis of acute cellular changes seen in nasal mucosa of Wistar-Albino rats exposed to different doses of oleoresin capsicum for various time periods by means of scanning electron microscopy. Thirty-five Wistar-Albino rats were divided into five groups of seven rats each. 6-gram oleoresin capsicum per second was sprayed into cages of the groups except group 1. Spray times and duration of exposure to pepper gasses were different for each group. Thirty minutes after the exposure, the animals were killed and specimens from their nasal mucosas were harvested and examined under scanning electron microscope. Mucosal damage was scored from 0-4 points. Mean values of nasal mucosa damage scores of the groups were calculated and compared statistically. Average damage scores of the groups exposed to identical doses of oleoresin capsicum for various exposure times were compared and a statistically significant difference was seen between Groups 2 and 3 (p 0.05). Average damage scores of the groups exposed to various doses for identical exposure times were compared, and statistically significant differences were observed between Groups 2 and 4 and also Groups 3 and 5 (p mucosa. The extent of these destructive changes increases with the prolonged exposure to higher doses. Besides, exposure time also stands out as an influential factor on the extent of the destructive changes.

  7. Scanning Electron Microscopy Evaluation of an EX-PRESS Mini Glaucoma Shunt After Explantation.

    Science.gov (United States)

    Tognetto, Daniele; Cecchini, Paolo; D'Aloisio, Rossella; Vattovani, Odilla; Turco, Gianluca

    2017-01-01

    We report a case of an explanted stainless steel miniature glaucoma drainage device (EX-PRESS) implanted under a scleral flap for pseudoexfoliation open-angle glaucoma surgical treatment. The glaucoma shunt was implanted in a 75-year-old white man with medically refractive glaucoma. Cataract surgery was performed simultaneously. After 2 years, the shunt extruded through the scleral flap and the conjunctiva and it was, therefore, explanted. Scanning electron microscopy images of the EX-PRESS mini glaucoma shunt were acquired to verify the patency of the device lumen and the presence of fibrosis or cellular adhesion on the device. Energy dispersive spectroscopy for chemical surface characterization of the EX-PRESS shunt was performed. Scanning electron microscopy-acquired images showed minimal extracellular material proliferation on the lumen device. The energy dispersive spectroscopy analysis revealed a high peak of carbon suggesting the organic nature of the residuals found on the shunt lumen. The surface showed few superficial pits, likely due to an initial corrosion process.

  8. New Aspidoderidae species parasite of Didelphis aurita (Mammalia: Didelphidae): a light and scanning electron microscopy approach.

    Science.gov (United States)

    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.

  9. Microfluidic device for a rapid immobilization of zebrafish larvae in environmental scanning electron microscopy.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  11. Spatial Domain based Image Enhancement Techniques for Scanned Electron Microscope-SEM-images

    Directory of Open Access Journals (Sweden)

    Rakhi Chanana

    2011-07-01

    Full Text Available The growing need for efficiently processing and analyzing the information contained in digital images is a continuous challenge in order to apply image processing. Digital images are captured from different imaging media elements like cameras, scanned electron microscopes etc. While going through the imaging process, Images get distorted in various forms resulting in extreme dark or light areas. All these things lead to the loss of information. The goal in each case is to extract useful information. In that case, Image processing extracts useful information by applying various image enhancement and algorithms. In this paper, we have discussed a practical implementation of various enhancement methods for Scanned Electron Microscope (SEM images and their experimental results. SEM images lead to very dark and light areas in an image. While imaging the information in the front scene is not only the source of information but some scenes on the dark side can also have the useful information. Before processing any further we require to enhance such images and one of the enhancement techniques i.e. Histogram Statistics comes out to be an ideal approach.

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

    Science.gov (United States)

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

    2015-06-01

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

  13. Analysis of membrane electrode assembly (MEA) by environmental scanning electron microscope (ESEM)

    Energy Technology Data Exchange (ETDEWEB)

    Yu, H.M.; Schumacher, J.O.; Zobel, M.; Hebling, C. [Fraunhofer Institute of Solar Energy System, Heidenhofstrasse 2, D-79110 Freiburg (Germany)

    2005-08-18

    To date, the available equipment for characterising the microstructure of membrane electrode assembly (MEA) is still not well developed. For example, applying the normal scanning electron microscope (SEM) only provides information on the dry structure of MEAs. This paper presents a microstructure analysis method of MEAs in proton exchange membrane fuel cells (PEMFC). The microstructure analysis in this paper utilises the environmental scanning electron microscope (ESEM), which shows its advantage on the sample microstructure analysis in wet mode. When water is present, the characteristics of the MEA, especially the hydrophobic and/or hydrophilic properties, are distinguishable on the ESEM images. With proper temperature and pressure control, the water distribution within both the membrane and the catalyst layer can be viewed by ESEM. Based on ESEM measurement and mercury porosity measurement, the distributions of hydrophobic and hydrophilic pores in MEA have been analyzed. By means of ESEM and energy dispersive X-ray (EDX), a degraded MEA is characterized. The microstructure change of the degraded MEA has been discussed. The results provide helpful information for the understanding of MEAs in PEMFC. (author)

  14. Anatomical descriptions of silicified woods from Madagascar and Indonesia by scanning electron microscopy.

    Science.gov (United States)

    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.

  15. The identification of black carbon particles with the analytical scanning electron microscope. Methods and initial results

    Energy Technology Data Exchange (ETDEWEB)

    Stoffyn-Egli, P. [MicroChem, Geochemistry Consultants, East Jeddore, Nova Scotia (Canada); Potter, T.M.; Leonard, J.D.; Pocklington, R. [Department of Fisheries and Oceans, Bedford Institute of Oceanography, Dartmouth, Nova Scotia (Canada)

    1997-04-09

    Combustion of fossil fuel and vegetation produces large quantities of black carbon particles (BCP) which are dispersed by winds over large areas. Once deposited in the sediment, BCP constitute an historic record of anthropogenic activities and wildfires. For BCP to be significant environmental indicators, it is necessary to determine their source as precisely as possible. A method has been developed to differentiate BCP from other carbonaceous particles, and to assign them to coal, oil, or biomass combustion using a scanning electron microscope equipped with an elemental detector (Analytical Scanning Electron Microscope, ASEM). BCP were identified in the ASEM as particles with an O/C atomic ratio of less than 0.15. Morphology (shape and surface texture) and trace element content (S and Cl) were used to classify BCP according to source using samples of known origin (oil, coal and wood fly-ash) and marine sediment samples from Halifax Inlet, which has undergone progressive urbanisation and industrialization over the last 250 years. The method is applicable to a wide size range of BCP and complete isolation of the BCP from the rest of the sample is not necessary

  16. 3D imaging by serial block face scanning electron microscopy for materials science using ultramicrotomy.

    Science.gov (United States)

    Hashimoto, Teruo; Thompson, George E; Zhou, Xiaorong; Withers, Philip J

    2016-04-01

    Mechanical serial block face scanning electron microscopy (SBFSEM) has emerged as a means of obtaining three dimensional (3D) electron images over volumes much larger than possible by focused ion beam (FIB) serial sectioning and at higher spatial resolution than achievable with conventional X-ray computed tomography (CT). Such high resolution 3D electron images can be employed for precisely determining the shape, volume fraction, distribution and connectivity of important microstructural features. While soft (fixed or frozen) biological samples are particularly well suited for nanoscale sectioning using an ultramicrotome, the technique can also produce excellent 3D images at electron microscope resolution in a time and resource-efficient manner for engineering materials. Currently, a lack of appreciation of the capabilities of ultramicrotomy and the operational challenges associated with minimising artefacts for different materials is limiting its wider application to engineering materials. Consequently, this paper outlines the current state of the art for SBFSEM examining in detail how damage is introduced during slicing and highlighting strategies for minimising such damage. A particular focus of the study is the acquisition of 3D images for a variety of metallic and coated systems.

  17. New insights into subsurface imaging of carbon nanotubes in polymer composites via scanning electron microscopy

    Science.gov (United States)

    Zhao, Minhua; Ming, Bin; Kim, Jae-Woo; Gibbons, Luke J.; Gu, Xiaohong; Nguyen, Tinh; Park, Cheol; Lillehei, Peter T.; Villarrubia, J. S.; Vladár, András E.; Liddle, J. Alexander

    2015-02-01

    Despite many studies of subsurface imaging of carbon nanotube (CNT)-polymer composites via scanning electron microscopy (SEM), significant controversy exists concerning the imaging depth and contrast mechanisms. We studied CNT-polyimide composites and, by three-dimensional reconstructions of captured stereo-pair images, determined that the maximum SEM imaging depth was typically hundreds of nanometers. The contrast mechanisms were investigated over a broad range of beam accelerating voltages from 0.3 to 30 kV, and ascribed to modulation by embedded CNTs of the effective secondary electron (SE) emission yield at the polymer surface. This modulation of the SE yield is due to non-uniform surface potential distribution resulting from current flows due to leakage and electron beam induced current. The importance of an external electric field on SEM subsurface imaging was also demonstrated. The insights gained from this study can be generally applied to SEM nondestructive subsurface imaging of conducting nanostructures embedded in dielectric matrices such as graphene-polymer composites, silicon-based single electron transistors, high resolution SEM overlay metrology or e-beam lithography, and have significant implications in nanotechnology.

  18. Serial Block-Face Scanning Electron Microscopy to Reconstruct Three-Dimensional Tissue Nanostructure

    Directory of Open Access Journals (Sweden)

    Denk Winfried

    2004-01-01

    Full Text Available 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.

  19. Is Canada ready for patient accessible electronic health records? A national scan

    Directory of Open Access Journals (Sweden)

    Eysenbach Gunther

    2008-07-01

    Full Text Available Abstract Background Access to personal health information through the electronic health record (EHR is an innovative means to enable people to be active participants in their own health care. Currently this is not an available option for consumers of health. The absence of a key technology, the EHR, is a significant obstacle to providing patient accessible electronic records. To assess the readiness for the implementation and adoption of EHRs in Canada, a national scan was conducted to determine organizational readiness and willingness for patient accessible electronic records. Methods A survey was conducted of Chief Executive Officers (CEOs of Canadian public and acute care hospitals. Results Two hundred thirteen emails were sent to CEOs of Canadian general and acute care hospitals, with a 39% response rate. Over half (54.2% of hospitals had some sort of EHR, but few had a record that was predominately electronic. Financial resources were identified as the most important barrier to providing patients access to their EHR and there was a divergence in perceptions from healthcare providers and what they thought patients would want in terms of access to the EHR, with providers being less willing to provide access and patients desire for greater access to the full record. Conclusion As the use of EHRs becomes more commonplace, organizations should explore the possibility of responding to patient needs for clinical information by providing access to their EHR. The best way to achieve this is still being debated.

  20. New Insights on Subsurface Imaging of Carbon Nanotubes in Polymer Composites via Scanning Electron Microscopy

    Science.gov (United States)

    Zhao, Minhua; Ming, Bin; Kim, Jae-Woo; Gibbons, Luke J.; Gu, Xiaohong; Nguyen, Tinh; Park, Cheol; Lillehei, Peter T.; Villarrubia, J. S.; Vladar, Andras E.; hide

    2015-01-01

    Despite many studies of subsurface imaging of carbon nanotube (CNT)-polymer composites via scanning electron microscopy (SEM), significant controversy exists concerning the imaging depth and contrast mechanisms. We studied CNT-polyimide composites and, by threedimensional reconstructions of captured stereo-pair images, determined that the maximum SEM imaging depth was typically hundreds of nanometers. The contrast mechanisms were investigated over a broad range of beam accelerating voltages from 0.3 to 30 kV, and ascribed to modulation by embedded CNTs of the effective secondary electron (SE) emission yield at the polymer surface. This modulation of the SE yield is due to non-uniform surface potential distribution resulting from current flows due to leakage and electron beam induced current. The importance of an external electric field on SEM subsurface imaging was also demonstrated. The insights gained from this study can be generally applied to SEM nondestructive subsurface imaging of conducting nanostructures embedded in dielectric matrices such as graphene-polymer composites, silicon-based single electron transistors, high resolution SEM overlay metrology or e-beam lithography, and have significant implications in nanotechnology.