Superconducting phonon spectroscopy using a low-temperature scanning tunneling microscope

NASA Technical Reports Server (NTRS)

Leduc, H. G.; Kaiser, W. J.; Hunt, B. D.; Bell, L. D.; Jaklevic, R. C.

1989-01-01

The low-temperature scanning tunneling microscope (STM) system described by LeDuc et al. (1987) was used to observe the phonon density of states effects in a superconductor. Using techniques based on those employed in macroscopic tunneling spectroscopy, electron tunneling current-voltage (I-V) spectra were measured for NbN and Pb, and dI/dV vs V spectra were measured using standard analog derivative techniques. I-V measurements on NbN and Pb samples under typical STM conditions showed no evidence for multiparticle tunneling effects.

Transmission Electron Microscope Observations of Phyllosilicate Development During Experimental Aqueous Alteration of Allende

NASA Technical Reports Server (NTRS)

Jones, C. L.; Brearley, A. J.

2000-01-01

Samples of Allende have been altered hydrothermally under oxidizing conditions at 200 C. TEM studies show that within 30 days evidence of replacement of matrix olivines by fine-grained serpentine is present and by 90 days complete alteration of many grains has occurred.

Transmission electron microscope CCD camera

DOEpatents

Downing, Kenneth H.

1999-01-01

In order to improve the performance of a CCD camera on a high voltage electron microscope, an electron decelerator is inserted between the microscope column and the CCD. This arrangement optimizes the interaction of the electron beam with the scintillator of the CCD camera while retaining optimization of the microscope optics and of the interaction of the beam with the specimen. Changing the electron beam energy between the specimen and camera allows both to be optimized.

76 FR 65696 - Battelle Energy Alliance, et al.;

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-24

... of Texas at Austin, Austin, TX 78712. Instrument: Electron Microscope. Manufacturer: FEI Company, the... research or scientific educational uses requiring an electron microscope. We know of no electron microscope...

Densities of 5-15 micron interplanetary dust particles

NASA Technical Reports Server (NTRS)

Love, S. G.; Joswiak, D. J.; Brownlee, D. E.

1993-01-01

We have measured the densities of about 100 5-15 micron stratospheric IDPs. Great care was taken to minimize selection bias in the sample population. Masses were determined using an absolute x-ray analysis technique with a transmission electron microscope, and volumes were found using scanning electron microscope imagery. Unmelted chondritic particles have densities between 0.5 and 6.0 g/cc. Roughly half of the particles have densities below 2 g/cc, indicating appreciable porosity, but porosities greater than about 70 percent are rare. IDPs with densities above 3.5 g/cc usually contain large sulfide grains. We find no evidence of bimodality in the unmelted particle density distribution. Chondritic spherules (melted particles) have densities near 3.5 g/cc, consistent with previous results for deep sea spherules.

Electron microscopic visualization of autophagosomes induced by infection of human papillomavirus pseudovirions

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

Ishii, Yoshiyuki, E-mail: yishii@nih.go.jp

2013-04-19

Highlights: •HPV16 pseudovirions (16PsVs) infection induces an autophagy response. •The autophagy was analyzed by transmission electron microscope (TEM). •TEM showed the double-membrane vesicles in HeLa cells inoculated with 16PsVs. •These vesicles incorporated 16PsVs particles in the lumen. •These results imply that autophagosomes are generated from the plasma membrane. -- Abstract: Autophagy is a bulk degradation process for subcellular proteins and organelles to manage cell starvation. Autophagy is associated with the formation of autophagosomes and further functions as a defense mechanism against infection by various pathogens. Human papillomavirus (HPV) infection induces an autophagy response, such as up-regulation of marker proteins formore » autophagy, in host keratinocytes. However, direct microscopic evidence for autophagy induction by HPV infection is still lacking. Here, I report an electron microscopic analysis of autophagosomes elicited by the entry of HPV pseudovirions (PsVs). HeLa cells showed enhanced infectivity for PsVs of HPV type 16 (16PsVs) when treated with an autophagy inhibitor, suggesting the involvement of autophagy in HPV infection. In HeLa cells inoculated with 16PsVs, transmission electron microscopy showed the presence of cup-shaped, double-membrane vesicles (phagophores) and double-membrane-bound vesicles, which are typical structures of autophagosomes. These double-membrane vesicles displayed a large lumen volume and incorporated 10–50 16PsVs particles in the lumen. These results demonstrate that autophagy is indeed induced during the HPV16 entry process and imply that autophagosomes are generated from the plasma membrane by HPV infection.« less

Topical anaesthetic and tear film stability.

PubMed

Mengher, L S; Pandher, K S; Bron, A J

1986-02-01

The effect of unpreserved topical anaesthetic on tear film stability (0.4% oxybuprocaine hydrochloride) was investigated in a double masked randomised study in 12 healthy volunteers, using a noninvasive tear film break up technique (NIBUT). It was found that the topical anaesthetic did not reduce the pre-corneal tear film stability, contrary to the electron microscopic evidence.

Mars Life? - Microscopic Tube-like Structures

NASA Technical Reports Server (NTRS)

1996-01-01

This high-resolution scanning electron microscope image shows an unusual tube-like structural form that is less than 1/100th the width of a human hair in size found in meteorite ALH84001, a meteorite believed to be of Martian origin. Although this structure is not part of the research published in the Aug. 16 issue of the journal Science, it is located in a similar carbonate glob in the meteorite. This structure will be the subject of future investigations that could confirm whether or not it is fossil evidence of primitive life on Mars 3.6 billion years ago.

Electron microscopy and antigenic studies of uncharacterized viruses. I. Evidence suggesting the placement of viruses in families Arenaviridae, Paramyxoviridae, or Poxviridae.

PubMed

Zeller, H G; Karabatsos, N; Calisher, C H; Digoutte, J P; Murphy, F A; Shope, R E

1989-01-01

During approximately 35 years, investigators in various laboratories studying arbovirus ecology and epidemiology accumulated many virus isolates, more than 60 of which were not characterized or placed in taxa. By a combination of electron microscopic and antigenic studies we collected information sufficient to provisionally classify 60 isolates. Electron microscopic observations suggest that 20 are members of the virus family Bunyaviridae, 20 Rhabdoviridae, 14 Reoviridae, one Togaviridae, one Paramyxoviridae (Mapuera virus, from a bat), and one Poxviridae (Yoka virus, from mosquitoes). Serologic studies provided evidence sufficient to place some of these viruses in recognized antigenic groups, within families and genera, and to establish new antigenic groups and taxa for others. Three viruses were found to have morphologic and morphogenetic characteristics consistent with those of members of the family Arenaviridae: Quaranfil virus, a human pathogen, Johnston Atoll virus, isolated from birds and ticks, and Araguari virus, isolated from an opossum. This, the first in a series of three papers, described methods used for these investigations and also presents descriptions of viruses provisionally placed in the families Arenaviridae, Paramyxoviridae, or Poxviridae. Descriptions of viruses provisionally placed in families Bunyaviridae and Reoviridae are published in the second and third papers, respectively. Viruses of the family Rhabdoviridae have been described separately.

Orientation and phase mapping in the transmission electron microscope using precession-assisted diffraction spot recognition: state-of-the-art results.

PubMed

Viladot, D; Véron, M; Gemmi, M; Peiró, F; Portillo, J; Estradé, S; Mendoza, J; Llorca-Isern, N; Nicolopoulos, S

2013-10-01

A recently developed technique based on the transmission electron microscope, which makes use of electron beam precession together with spot diffraction pattern recognition now offers the possibility to acquire reliable orientation/phase maps with a spatial resolution down to 2 nm on a field emission gun transmission electron microscope. The technique may be described as precession-assisted crystal orientation mapping in the transmission electron microscope, precession-assisted crystal orientation mapping technique-transmission electron microscope, also known by its product name, ASTAR, and consists in scanning the precessed electron beam in nanoprobe mode over the specimen area, thus producing a collection of precession electron diffraction spot patterns, to be thereafter indexed automatically through template matching. We present a review on several application examples relative to the characterization of microstructure/microtexture of nanocrystalline metals, ceramics, nanoparticles, minerals and organics. The strengths and limitations of the technique are also discussed using several application examples. ©2013 The Authors. Journal of Microscopy published by John Wiley & Sons Ltd on behalf of Royal Microscopical Society.

Edge mixing dynamics in graphene p–n junctions in the quantum Hall regime

PubMed Central

Matsuo, Sadashige; Takeshita, Shunpei; Tanaka, Takahiro; Nakaharai, Shu; Tsukagoshi, Kazuhito; Moriyama, Takahiro; Ono, Teruo; Kobayashi, Kensuke

2015-01-01

Massless Dirac electron systems such as graphene exhibit a distinct half-integer quantum Hall effect, and in the bipolar transport regime co-propagating edge states along the p–n junction are realized. Additionally, these edge states are uniformly mixed at the junction, which makes it a unique structure to partition electrons in these edge states. Although many experimental works have addressed this issue, the microscopic dynamics of electron partition in this peculiar structure remains unclear. Here we performed shot-noise measurements on the junction in the quantum Hall regime as well as at zero magnetic field. We found that, in sharp contrast with the zero-field case, the shot noise in the quantum Hall regime is finite in the bipolar regime, but is strongly suppressed in the unipolar regime. Our observation is consistent with the theoretical prediction and gives microscopic evidence that the edge states are uniquely mixed along the p–n junction. PMID:26337445

Spectral function of few electrons in quantum wires and carbon nanotubes as a signature of Wigner localization

NASA Astrophysics Data System (ADS)

Secchi, Andrea; Rontani, Massimo

2012-03-01

We demonstrate that the profile of the space-resolved spectral function at finite temperature provides a signature of Wigner localization for electrons in quantum wires and semiconducting carbon nanotubes. Our numerical evidence is based on the exact diagonalization of the microscopic Hamiltonian of few particles interacting in gate-defined quantum dots. The minimal temperature required to suppress residual exchange effects in the spectral function image of (nanotubes) quantum wires lies in the (sub)kelvin range.

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

PubMed

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

2015-08-01

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

Distinction between amorphous and healed planar deformation features in shocked quartz using composite color scanning electron microscope cathodoluminescence (SEM-CL) imaging

NASA Astrophysics Data System (ADS)

Hamers, Maartje F.; Pennock, Gill M.; Herwegh, Marco; Drury, Martyn R.

2016-10-01

Planar deformation features (PDFs) in quartz are one of the most reliable and most widely used forms of evidence for hypervelocity impact. PDFs can be identified in scanning electron microscope cathodoluminescence (SEM-CL) images, but not all PDFs show the same CL behavior: there are nonluminescent and red luminescent PDFs. This study aims to explain the origin of the different CL emissions in PDFs. Focused ion beam (FIB) thin foils were prepared of specific sample locations selected in composite color SEM-CL images and were analyzed in a transmission electron microscope (TEM). The FIB preparation technique allowed a direct, often one-to-one correlation between the CL images and the defect structure observed in TEM. This correlation shows that composite color SEM-CL imaging allows distinction between amorphous PDFs on one hand and healed PDFs and basal Brazil twins on the other: nonluminescent PDFs are amorphous, while healed PDFs and basal Brazil twins are red luminescent, with a dominant emission peak at 650 nm. We suggest that the red luminescence is the result of preferential beam damage along dislocations, fluid inclusions, and twin boundaries. Furthermore, a high-pressure phase (possibly stishovite) in PDFs can be detected in color SEM-CL images by its blue luminescence.

Designs for a quantum electron microscope.

PubMed

Kruit, P; Hobbs, R G; Kim, C-S; Yang, Y; Manfrinato, V R; Hammer, J; Thomas, S; Weber, P; Klopfer, B; Kohstall, C; Juffmann, T; Kasevich, M A; Hommelhoff, P; Berggren, K K

2016-05-01

One of the astounding consequences of quantum mechanics is that it allows the detection of a target using an incident probe, with only a low probability of interaction of the probe and the target. This 'quantum weirdness' could be applied in the field of electron microscopy to generate images of beam-sensitive specimens with substantially reduced damage to the specimen. A reduction of beam-induced damage to specimens is especially of great importance if it can enable imaging of biological specimens with atomic resolution. Following a recent suggestion that interaction-free measurements are possible with electrons, we now analyze the difficulties of actually building an atomic resolution interaction-free electron microscope, or "quantum electron microscope". A quantum electron microscope would require a number of unique components not found in conventional transmission electron microscopes. These components include a coherent electron beam-splitter or two-state-coupler, and a resonator structure to allow each electron to interrogate the specimen multiple times, thus supporting high success probabilities for interaction-free detection of the specimen. Different system designs are presented here, which are based on four different choices of two-state-couplers: a thin crystal, a grating mirror, a standing light wave and an electro-dynamical pseudopotential. Challenges for the detailed electron optical design are identified as future directions for development. While it is concluded that it should be possible to build an atomic resolution quantum electron microscope, we have also identified a number of hurdles to the development of such a microscope and further theoretical investigations that will be required to enable a complete interpretation of the images produced by such a microscope. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Cytochemical and Cytofluorometric Evidence for Guard Cell Photosystems 1

PubMed Central

Vaughn, Kevin C.; Outlaw, William H.

1983-01-01

Evidence for photosynthetic linear electron transport in guard cells was obtained with two sensitive methods of high spacial resolution. Light-dependent diaminobenzidine oxidation (an indicator of PSI) and DCMU-sensitive, light-dependent thiocarbamyl nitroblue tetrazolium reduction (an indicator of PSII) were observed in guard cell plastids of Hordeum vulgare L. cv Himalaya using electron microscopic cytochemical procedures. DCMU-sensitive Chl a fluorescence induction (an indicator of PSII) was detected in individual guard cell pairs of Vicia faba L. cv Longpod using an ultramicrofluorometer. At least for these species, we conclude these results are proof for the presence of PSII in guard cell chloroplasts, which until now has been somewhat controversial. Images Fig. 2 Fig. 1 PMID:16662840

Identification and characterization of Citrus yellow vein clearing virus, a putative new member of the genus Mandarivirus infecting Citrus spp.

USDA-ARS?s Scientific Manuscript database

Yellow vein clearing virus, an uncharacterized filamentous virus, was first observed in Pakistan in 1988 and later in India in 1997 in Etrog citron (Citrus medica). Based on electron microscopic evidence of filamentous particles, the virus, provisionally named Citrus yellow vein clearing virus (CYVC...

Hemorrhagic enteritis in captive American kestrels (Falco sparverius)

USGS Publications Warehouse

Sileo, L.; Franson, J.C.; Graham, D.L.; Domermuth, C.H.; Rattner, B.A.; Pattee, O.H.

1983-01-01

Hemorrhagic enteritis and hepatitis of suspected adenovirus etiology were the apparent cause of death of nine captive American kestrels. Cloacal hemorrhage was the only prominent gross lesion: disseminated hepatocellular necrosis, and intranuclear inclusion bodies were evident microscopically. Electron microscopy revealed numerous adenovirus-like particles associated with the hepatic lesions. Attempts to serologically identify the agent were unsuccessful.

Size effects on melting and wetting in the Ga-Pb nano-alloy

NASA Astrophysics Data System (ADS)

Allione, M.; Kofman, R.; Celestini, F.; Lereah, Y.

2009-04-01

Ga-Pb alloys with 15 at% Pb mean concentration have been prepared at the nanoscale by means of evaporation-condensation technique in ultra high vacuum conditions. Transmission electron microscope images indicate that at room temperature, the system is a two-components breath figure composed of liquid Ga nanodrops containing Pb nanocrystals. Some thermodynamic properties of this nano-alloy are investigated for different temperatures and particle sizes. The results obtained put in evidence a large modification of the Ga-Pb bulk phase diagram: a decrease of the melting temperatures of the two components as well as the ones of the miscibility gap. Changes in the microscopic structure of the system as a function of temperature have been investigated and a full wetting transition from a dry to a completely wet state has been put in evidence.

75 FR 13486 - Application(s) for Duty-Free Entry of Scientific Instruments

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... University, One Waterfront Place, PO Box 6024, Morgantown, WV 26506. Instrument: Electron Microscope.... Justification for Duty-Free Entry: There are no domestic manufacturers of this type of electron microscope.... Lawrence University, 23 Romoda Drive, Canton, NY 13617. Instrument: Electron Microscope. Manufacturer: FEI...

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The Design and Construction of a Simple Transmission Electron Microscope for Educational Purposes.

ERIC Educational Resources Information Center

Hearsey, Paul K.

This document presents a model for a simple transmission electron microscope for educational purposes. This microscope could demonstrate thermonic emission, particle acceleration, electron deflection, and flourescence. It is designed to be used in high school science courses, particularly physics, taking into account the size, weight, complexity…

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Secondary electron imaging of monolayer materials inside a transmission electron microscope

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

Cretu, Ovidiu, E-mail: cretu.ovidiu@nims.go.jp; Lin, Yung-Chang; Suenaga, Kazutomo

2015-08-10

A scanning transmission electron microscope equipped with a backscattered and secondary electron detector is shown capable to image graphene and hexagonal boron nitride monolayers. Secondary electron contrasts of the two lightest monolayer materials are clearly distinguished from the vacuum level. A signal difference between these two materials is attributed to electronic structure differences, which will influence the escape probabilities of the secondary electrons. Our results show that the secondary electron signal can be used to distinguish between the electronic structures of materials with atomic layer sensitivity, enhancing its applicability as a complementary signal in the analytical microscope.

Integration of a high-NA light microscope in a scanning electron microscope.

PubMed

Zonnevylle, A C; Van Tol, R F C; Liv, N; Narvaez, A C; Effting, A P J; Kruit, P; Hoogenboom, J P

2013-10-01

We present an integrated light-electron microscope in which an inverted high-NA objective lens is positioned inside a scanning electron microscope (SEM). The SEM objective lens and the light objective lens have a common axis and focal plane, allowing high-resolution optical microscopy and scanning electron microscopy on the same area of a sample simultaneously. Components for light illumination and detection can be mounted outside the vacuum, enabling flexibility in the construction of the light microscope. The light objective lens can be positioned underneath the SEM objective lens during operation for sub-10 μm alignment of the fields of view of the light and electron microscopes. We demonstrate in situ epifluorescence microscopy in the SEM with a numerical aperture of 1.4 using vacuum-compatible immersion oil. For a 40-nm-diameter fluorescent polymer nanoparticle, an intensity profile with a FWHM of 380 nm is measured whereas the SEM performance is uncompromised. The integrated instrument may offer new possibilities for correlative light and electron microscopy in the life sciences as well as in physics and chemistry. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

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

PubMed

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

2010-03-01

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

Automated thin-film analyses of hydrated interplanetary dust particles in the analytical electron microscope

NASA Technical Reports Server (NTRS)

Germani, M. S.; Bradley, J. P.; Brownlee, D. E.

1990-01-01

A 200 keV electron microscope was used to obtain elemental analyses from over 4000 points on thin sections of eight 'layer silicate' class interplanetary dust particles (IDPs). Major and minor element abundances from a volume approaching that of a cylinder 50 nm in diameter were observed. Mineral phases and their relative abundances in the thin sections were identified and petrographic characteristics were determined. Three of the particles contained smectite (1.0-1.2 nm basal spacing) and two contained serpentine (0.7 nm basal spacing). The point count analyses and Mg-Si-Fe ternary diagrams show that one of the serpentine-containing IDPs is similar to CI and CM chondritic meteorites. The IDPs exhibit evidence of aqueous processing, but they have typically experienced only short range, submicrometer scale alteration. The IDPs may provide a broad sampling of the asteroid belt.

Research of the Dispersity of the Functional Sericite/Methylphenyl- Silicone Resin

PubMed Central

Jiang, B.; Zhu, C. C.; Huang, Y. D.

2015-01-01

In order to improve the homogeneity and dispersity of the sericite in methylphenyl-silicone resin, the agglomerate state of the sericites was controlled effectively. The dispersive model of the sericite in methylphenyl-silicone resin was designed also. First, the modified sericite was prepared using hexadecyl trimethyl ammonium bromide as the intercalating agent. Then, functional sericite was incorporated into methylphenyl-silicone by terminal hydroxyl. The structure and dispersive performance of the hybrid polymers was charactered by analytical instruments. Scanning electron microscopy and Transmission electron microscope, Laser scanning confocal microscope and X-ray diffraction analysis showed that functional sericite was dispersed homogeneously in methylphenyl-silicone resin matrix. X-ray photoelectron spectroscopy analysis showed that the absorption peaks of the Si-OH band of methylphenyl-silicone resin were decreased and the Si-O-Si band was increased. This change evidently showed a significant role to enhance the reaction degree of the functional sericite in methylphenyl-silicone resin. PMID:26061002

In situ study on atomic mechanism of melting and freezing of single bismuth nanoparticles

PubMed Central

Li, Yingxuan; Zang, Ling; Jacobs, Daniel L.; Zhao, Jie; Yue, Xiu; Wang, Chuanyi

2017-01-01

Experimental study of the atomic mechanism in melting and freezing processes remains a formidable challenge. We report herein on a unique material system that allows for in situ growth of bismuth nanoparticles from the precursor compound SrBi2Ta2O9 under an electron beam within a high-resolution transmission electron microscope (HRTEM). Simultaneously, the melting and freezing processes within the nanoparticles are triggered and imaged in real time by the HRTEM. The images show atomic-scale evidence for point defect induced melting, and a freezing mechanism mediated by crystallization of an intermediate ordered liquid. During the melting and freezing, the formation of nucleation precursors, nucleation and growth, and the relaxation of the system, are directly observed. Based on these observations, an interaction–relaxation model is developed towards understanding the microscopic mechanism of the phase transitions, highlighting the importance of cooperative multiscale processes. PMID:28194017

In situ study on atomic mechanism of melting and freezing of single bismuth nanoparticles

NASA Astrophysics Data System (ADS)

Li, Yingxuan; Zang, Ling; Jacobs, Daniel L.; Zhao, Jie; Yue, Xiu; Wang, Chuanyi

2017-02-01

Experimental study of the atomic mechanism in melting and freezing processes remains a formidable challenge. We report herein on a unique material system that allows for in situ growth of bismuth nanoparticles from the precursor compound SrBi2Ta2O9 under an electron beam within a high-resolution transmission electron microscope (HRTEM). Simultaneously, the melting and freezing processes within the nanoparticles are triggered and imaged in real time by the HRTEM. The images show atomic-scale evidence for point defect induced melting, and a freezing mechanism mediated by crystallization of an intermediate ordered liquid. During the melting and freezing, the formation of nucleation precursors, nucleation and growth, and the relaxation of the system, are directly observed. Based on these observations, an interaction-relaxation model is developed towards understanding the microscopic mechanism of the phase transitions, highlighting the importance of cooperative multiscale processes.

In situ study on atomic mechanism of melting and freezing of single bismuth nanoparticles.

PubMed

Li, Yingxuan; Zang, Ling; Jacobs, Daniel L; Zhao, Jie; Yue, Xiu; Wang, Chuanyi

2017-02-13

Experimental study of the atomic mechanism in melting and freezing processes remains a formidable challenge. We report herein on a unique material system that allows for in situ growth of bismuth nanoparticles from the precursor compound SrBi 2 Ta 2 O 9 under an electron beam within a high-resolution transmission electron microscope (HRTEM). Simultaneously, the melting and freezing processes within the nanoparticles are triggered and imaged in real time by the HRTEM. The images show atomic-scale evidence for point defect induced melting, and a freezing mechanism mediated by crystallization of an intermediate ordered liquid. During the melting and freezing, the formation of nucleation precursors, nucleation and growth, and the relaxation of the system, are directly observed. Based on these observations, an interaction-relaxation model is developed towards understanding the microscopic mechanism of the phase transitions, highlighting the importance of cooperative multiscale processes.

Manipulation of subsurface carbon nanoparticles in Bi 2 Sr 2 CaCu 2 O 8 + δ using a scanning tunneling microscope

DOE PAGES

Stollenwerk, A. J.; Hurley, N.; Beck, B.; ...

2015-03-19

In this study, we present evidence that subsurface carbon nanoparticles in Bi₂Sr₂CaCu₂O 8+δ can be manipulated with nanometer precision using a scanning tunneling microscope. High resolution images indicate that most of the carbon particles remain subsurface after transport observable as a local increase in height as the particle pushes up on the surface. Tunneling spectra in the vicinity of these protrusions exhibit semiconducting characteristics with a band gap of approximately 1.8 eV, indicating that the incorporation of carbon locally alters the electronic properties near the surface.

The future of electron microscopy

DOE PAGES

Zhu, Yimei; Durr, Hermann

2015-04-01

Seeing is believing. So goes the old adage and seen evidence is undoubtedly satisfying because it can be interpreted easily, though not always correctly. For centuries, humans have developed such instruments as telescopes that observe the heavens and microscopes that reveal bacteria and viruses. The 2014 Nobel Prize in Chemistry was awarded to Eric Betzig, Stefan Hell, and William Moerner for their foundational work on superresolution fluorescence microscopy in which they overcame the Abbe diffraction limit for the resolving power of conventional light microscopes. (See Physics Today, December 2014, page 18.) That breakthrough enabled discoveries in biological research and testifiesmore » to the importance of modern microscopy.« less

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

PubMed

Jin, P; Li, X

2015-12-01

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

[Thirty years of the electron microscope investigation in zoology and parasitology in the Zoological Institute of the Russian Academy of Sciences].

PubMed

Shatrov, A B

2003-01-01

The history of the electron microscope investigations in zoology and parasitology in the Zoological Institute of the Russian Academy of Sciences and progress in scanning and transmission electron microscope investigations in this field of biology to the moment are briefly accounted.

75 FR 52928 - Emory University, et al., Notice of Consolidated Decision on Applications for Duty-Free Entry of...

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2010-08-30

... Consolidated Decision on Applications for Duty-Free Entry of Electron Microscopes This is a decision... 30322. Instrument: Electron Microscope. Manufacturer: JEOL, Ltd., Japan. Intended Use: See notice at 75... Department of Health, Menands, NY 12204-2719. Instrument: Electron Microscope. Manufacturer: JEOL Ltd., Japan...

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

PubMed

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

2016-05-01

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

Grayscale inhomogeneity correction method for multiple mosaicked electron microscope images

NASA Astrophysics Data System (ADS)

Zhou, Fangxu; Chen, Xi; Sun, Rong; Han, Hua

2018-04-01

Electron microscope image stitching is highly desired to acquire microscopic resolution images of large target scenes in neuroscience. However, the result of multiple Mosaicked electron microscope images may exist severe gray scale inhomogeneity due to the instability of the electron microscope system and registration errors, which degrade the visual effect of the mosaicked EM images and aggravate the difficulty of follow-up treatment, such as automatic object recognition. Consequently, the grayscale correction method for multiple mosaicked electron microscope images is indispensable in these areas. Different from most previous grayscale correction methods, this paper designs a grayscale correction process for multiple EM images which tackles the difficulty of the multiple images monochrome correction and achieves the consistency of grayscale in the overlap regions. We adjust overall grayscale of the mosaicked images with the location and grayscale information of manual selected seed images, and then fuse local overlap regions between adjacent images using Poisson image editing. Experimental result demonstrates the effectiveness of our proposed method.

A scoring scheme for evaluating magnetofossil identifications

NASA Astrophysics Data System (ADS)

Kopp, R. E.; Kirschvink, J. L.

2007-12-01

In many Quaternary lacustrine and marine settings, fossil magnetotactic bacteria are a major contributor to sedimentary magnetization [1]. Magnetite particles produced by magnetotactic bacteria have traits, shaped by natural selection, that increase the efficiency with which the bacteria utilize iron and also facilitate the recognition of the particles' biological origin. In particular, magnetotactic bacteria generally produce particles with characteristic shapes and narrow size and shape distributions that lie within the single domain stability field. The particles have effective positive magnetic anisotropy, produced by alignment in chains and frequently by particle elongation. In addition, the crystals are often nearly stochiometric and have few crystallographic defects. Yet, despite these distinctive traits, there are few identified magnetofossils that predate the Quaternary, and many putative identifications are highly controversial. We propose a six-criteria scoring scheme for evaluating identifications based on the quality of the geological, magnetic, and electron microscopic evidence. Our criteria are: (1) whether the geological context is well-constrained stratigraphically, and whether paleomagnetic evidence suggests a primary magnetization; (2) whether magnetic or microscopic evidence support the presence of significant single-domain magnetite; (3) whether magnetic or ferromagnetic resonance evidence indicates narrow size and shape distributions, and whether microscopic evidence reveals single-domain particles with truncated edges, elongate single-domain particles, and/or narrow size and shape distributions; (4) whether ferromagnetic resonance, low-temperature magnetic, or electron microscopic evidence reveals the presence of chains; (5) whether low-temperature magnetometry, energy dispersive X-ray spectroscopy, or other techniques demonstrate the near-stochiometry of the particles; and (6) whether high-resolution TEM indicates the near- absence of crystallographic defects. We use criterion 1 to set the threshold for determining whether a magnetofossil identification is robust. Criteria 3 and 4 are assigned numerical scores that range from 0 to 4, while criteria 2, 5, and 6 are evaluated based on presence or absence. Based on this scheme, the oldest robust magnetofossils yet found come from the Cretaceous chalk beds of southern England [2], though Lower Cambrian limestones of the Pestrotsvet Formation, Siberia Platform, only marginally fail to meet our robust criteria [3]. Although magnetofossils have also been reported from Proterozoic, Archean, and Martian rocks, none of these identifications are robust. References: [1] R. E. Kopp and J. L. Kirschvink (2007). Earth Sci. Rev. doi:10.1016/j.earscirev.2007.08.001. [2] P. Montgomery et al. (1998). Earth Planet. Sci. Lett. 156: 209-224. [3] S. B. R. Chang et al. (1987). Phys. Earth Planet. Int. 46: 289-303.

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

PubMed Central

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

2015-01-01

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

High cycle fatigue in the transmission electron microscope

DOE PAGES

Bufford, Daniel C.; Stauffer, Douglas; Mook, William M.; ...

2016-06-28

One of the most common causes of structural failure in metals is fatigue induced by cyclic loading. Historically, microstructure-level analysis of fatigue cracks has primarily been performed post mortem. However, such investigations do not directly reveal the internal structural processes at work near micro- and nanoscale fatigue cracks and thus do not provide direct evidence of active microstructural mechanisms. In this paper, the tension–tension fatigue behavior of nanocrystalline Cu was monitored in real time at the nanoscale by utilizing a new capability for quantitative cyclic mechanical loading performed in situ in a transmission electron microscope (TEM). Controllable loads were appliedmore » at frequencies from one to several hundred hertz, enabling accumulations of 10 6 cycles within 1 h. The nanometer-scale spatial resolution of the TEM allows quantitative fatigue crack growth studies at very slow crack growth rates, measured here at ~10 –12 m·cycle –1. This represents an incipient threshold regime that is well below the tensile yield stress and near the minimum conditions for fatigue crack growth. Evidence of localized deformation and grain growth within 150 nm of the crack tip was observed by both standard imaging and precession electron diffraction orientation mapping. Finally, these observations begin to reveal with unprecedented detail the local microstructural processes that govern damage accumulation, crack nucleation, and crack propagation during fatigue loading in nanocrystalline Cu.« less

High cycle fatigue in the transmission electron microscope

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

Bufford, Daniel C.; Stauffer, Douglas; Mook, William M.

One of the most common causes of structural failure in metals is fatigue induced by cyclic loading. Historically, microstructure-level analysis of fatigue cracks has primarily been performed post mortem. However, such investigations do not directly reveal the internal structural processes at work near micro- and nanoscale fatigue cracks and thus do not provide direct evidence of active microstructural mechanisms. In this paper, the tension–tension fatigue behavior of nanocrystalline Cu was monitored in real time at the nanoscale by utilizing a new capability for quantitative cyclic mechanical loading performed in situ in a transmission electron microscope (TEM). Controllable loads were appliedmore » at frequencies from one to several hundred hertz, enabling accumulations of 10 6 cycles within 1 h. The nanometer-scale spatial resolution of the TEM allows quantitative fatigue crack growth studies at very slow crack growth rates, measured here at ~10 –12 m·cycle –1. This represents an incipient threshold regime that is well below the tensile yield stress and near the minimum conditions for fatigue crack growth. Evidence of localized deformation and grain growth within 150 nm of the crack tip was observed by both standard imaging and precession electron diffraction orientation mapping. Finally, these observations begin to reveal with unprecedented detail the local microstructural processes that govern damage accumulation, crack nucleation, and crack propagation during fatigue loading in nanocrystalline Cu.« less

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

PubMed

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

2015-12-01

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

Size determination of Acipenser ruthenus spermatozoa in different types of electron microscopy.

PubMed

Psenicka, Martin; Tesarová, Martina; Tesitel, Jakub; Nebesárová, Jana

2010-07-01

In this study three types of scanning electron microscopes were used for the size determination of spermatozoa of sterlet Acipenser ruthenus - high vacuum scanning electron microscope (SEM, JEOL 6300), environmental scanning electron microscope (ESEM, Quanta 200 FEG), field emission scanning electron microscope (FESEM, JEOL 7401F) with cryoattachment Alto 2500 (Gatan) and transmission electron microscope (TEM, JEOL 1010). The use of particular microscopes was tied with different specimen preparation techniques. The aim of this study was to evaluate to what degree the type of used electron microscope can influence the size of different parts of spermatozoa. For high vacuum SEM the specimen was prepared using two slightly different procedures. After chemical fixation with 2.5% glutaraldehyde in 0.1M phosphate buffer and post-fixation by 1% osmium tetroxide, the specimen was dehydrated by acetone series and dried either by critical point method or by means of t-butylalcohol. For ESEM fresh, unfixed material was used, which was dropped on microscopic copper grids. In FESEM working in cryo-mode the specimen was observed in a frozen state. Ultrathin sections from chemically fixed and Epon embedded specimens were prepared for TEM observation. Distinct parts of sterlet spermatozoa were measured in each microscope and the data obtained was statistically processed. Results confirmed that the classical chemical procedure of specimen preparation for SEM including critical point drying method led to a significant contraction of all measured values, which could deviate up to 30% in comparison with values measured on the fresh chemically untreated specimen in ESEM. Surprisingly sperm dimensions determinated on ultrathin sections by TEM are comparable with values obtained in ESEM or FESEM. Copyright 2010 Elsevier Ltd. All rights reserved.

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

PubMed

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

2010-11-01

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

An electron microscope for the aberration-corrected era.

PubMed

Krivanek, O L; Corbin, G J; Dellby, N; Elston, B F; Keyse, R J; Murfitt, M F; Own, C S; Szilagyi, Z S; Woodruff, J W

2008-02-01

Improved resolution made possible by aberration correction has greatly increased the demands on the performance of all parts of high-end electron microscopes. In order to meet these demands, we have designed and built an entirely new scanning transmission electron microscope (STEM). The microscope includes a flexible illumination system that allows the properties of its probe to be changed on-the-fly, a third-generation aberration corrector which corrects all geometric aberrations up to fifth order, an ultra-responsive yet stable five-axis sample stage, and a flexible configuration of optimized detectors. The microscope features many innovations, such as a modular column assembled from building blocks that can be stacked in almost any order, in situ storage and cleaning facilities for up to five samples, computer-controlled loading of samples into the column, and self-diagnosing electronics. The microscope construction is described, and examples of its capabilities are shown.

Antibacterial and cytotoxic potential of silver nanoparticles synthesized using latex of Calotropis gigantea L.

NASA Astrophysics Data System (ADS)

Rajkuberan, Chandrasekaran; Sudha, Kannaiah; Sathishkumar, Gnanasekar; Sivaramakrishnan, Sivaperumal

2015-02-01

The present study aimed to synthesis silver nanoparticles (AgNPs) in a greener route using aqueous latex extract of Calotropis gigantea L. toward biomedical applications. Initially, synthesis of AgNPs was confirmed through UV-Vis spectroscopy which shows the surface plasmonic resonance peak (SPR) at 420 nm. Fourier transform infrared spectroscopy (FTIR) analysis provides clear evidence that protein fractions present in the latex extract act as reducing and stabilizing bio agents. Energy dispersive X-ray (EDAX) spectroscopy confirms the presence of silver as a major constituent element. X-ray diffractograms displays that the synthesized AgNPs were biphasic crystalline nature. Electron microscopic studies such as Field emission scanning electron microscopic (Fe-SEM) and Transmission electron microscope (TEM) reveals that synthesized AgNPs are spherical in shape with the size range between 5 and 30 nm. Further, crude latex aqueous extract and synthesized AgNPs were evaluated against different bacterial pathogens such as Bacillus cereus, Enterococci sp, Shigella sp, Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus and Escherichia coli. Compared to the crude latex aqueous extract, biosynthesized AgNPs exhibits a remarkable antimicrobial activity. Likewise invitro anticancer study manifests the cytotoxicity value of synthesized AgNPs against tested HeLa cells. The output of this study clearly suggesting that biosynthesized AgNPs using latex of C. gigantea can be used as promising nanomaterial for therapeutic application in context with nanodrug formulation.

Hartmann characterization of the PEEM-3 aberration-corrected X-ray photoemission electron microscope.

PubMed

Scholl, A; Marcus, M A; Doran, A; Nasiatka, J R; Young, A T; MacDowell, A A; Streubel, R; Kent, N; Feng, J; Wan, W; Padmore, H A

2018-05-01

Aberration correction by an electron mirror dramatically improves the spatial resolution and transmission of photoemission electron microscopes. We will review the performance of the recently installed aberration corrector of the X-ray Photoemission Electron Microscope PEEM-3 and show a large improvement in the efficiency of the electron optics. Hartmann testing is introduced as a quantitative method to measure the geometrical aberrations of a cathode lens electron microscope. We find that aberration correction leads to an order of magnitude reduction of the spherical aberrations, suggesting that a spatial resolution of below 100 nm is possible at 100% transmission of the optics when using x-rays. We demonstrate this improved performance by imaging test patterns employing element and magnetic contrast. Published by Elsevier B.V.

A new apparatus for electron tomography in the scanning electron microscope

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

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

2015-06-23

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

ultraLM and miniLM: Locator tools for smart tracking of fluorescent cells in correlative light and electron microscopy.

PubMed

Brama, Elisabeth; Peddie, Christopher J; Wilkes, Gary; Gu, Yan; Collinson, Lucy M; Jones, Martin L

2016-12-13

In-resin fluorescence (IRF) protocols preserve fluorescent proteins in resin-embedded cells and tissues for correlative light and electron microscopy, aiding interpretation of macromolecular function within the complex cellular landscape. Dual-contrast IRF samples can be imaged in separate fluorescence and electron microscopes, or in dual-modality integrated microscopes for high resolution correlation of fluorophore to organelle. IRF samples also offer a unique opportunity to automate correlative imaging workflows. Here we present two new locator tools for finding and following fluorescent cells in IRF blocks, enabling future automation of correlative imaging. The ultraLM is a fluorescence microscope that integrates with an ultramicrotome, which enables 'smart collection' of ultrathin sections containing fluorescent cells or tissues for subsequent transmission electron microscopy or array tomography. The miniLM is a fluorescence microscope that integrates with serial block face scanning electron microscopes, which enables 'smart tracking' of fluorescent structures during automated serial electron image acquisition from large cell and tissue volumes.

Spherical aberration correction in a scanning transmission electron microscope using a sculpted thin film.

PubMed

Shiloh, Roy; Remez, Roei; Lu, Peng-Han; Jin, Lei; Lereah, Yossi; Tavabi, Amir H; Dunin-Borkowski, Rafal E; Arie, Ady

2018-06-01

Nearly eighty years ago, Scherzer showed that rotationally symmetric, charge-free, static electron lenses are limited by an unavoidable, positive spherical aberration. Following a long struggle, a major breakthrough in the spatial resolution of electron microscopes was reached two decades ago by abandoning the first of these conditions, with the successful development of multipole aberration correctors. Here, we use a refractive silicon nitride thin film to tackle the second of Scherzer's constraints and demonstrate an alternative method for correcting spherical aberration in a scanning transmission electron microscope. We reveal features in Si and Cu samples that cannot be resolved in an uncorrected microscope. Our thin film corrector can be implemented as an immediate low cost upgrade to existing electron microscopes without re-engineering of the electron column or complicated operation protocols and can be extended to the correction of additional aberrations. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Immunogold labeling reveals subcellular localisation of silica nanoparticles in a human blood-brain barrier model

NASA Astrophysics Data System (ADS)

Ye, Dong; Anguissola, Sergio; O'Neill, Tiina; Dawson, Kenneth A.

2015-05-01

Subcellular location of nanoparticles has been widely investigated with fluorescence microscopy, via fluorescently labeled antibodies to visualise target antigens in cells. However, fluorescence microscopy, such as confocal or live cell imaging, has generally limited 3D spatial resolution. Conventional electron microscopy can be useful in bridging resolution gap, but still not ideal in resolving subcellular organelle identities. Using the pre-embedding immunogold electron microscopic imaging, we performed accurate examination of the intracellular trafficking and gathered further evidence of transport mechanisms of silica nanoparticles across a human in vitro blood-brain barrier model. Our approach can effectively immunolocalise a variety of intracellular compartments and provide new insights into the uptake and subcellular transport of nanoparticles.Subcellular location of nanoparticles has been widely investigated with fluorescence microscopy, via fluorescently labeled antibodies to visualise target antigens in cells. However, fluorescence microscopy, such as confocal or live cell imaging, has generally limited 3D spatial resolution. Conventional electron microscopy can be useful in bridging resolution gap, but still not ideal in resolving subcellular organelle identities. Using the pre-embedding immunogold electron microscopic imaging, we performed accurate examination of the intracellular trafficking and gathered further evidence of transport mechanisms of silica nanoparticles across a human in vitro blood-brain barrier model. Our approach can effectively immunolocalise a variety of intracellular compartments and provide new insights into the uptake and subcellular transport of nanoparticles. Electronic supplementary information (ESI) available: Nanoparticle characterisation data, preservation of cellular structures, staining controls, optimisation of size amplification via the silver enhancement, and more imaging results from anti-clathrin and anti-caveolin 1 immunolabeling. See DOI: 10.1039/c5nr01539a

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

PubMed

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

2010-08-01

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

Flexible high-voltage supply for experimental electron microscope

NASA Technical Reports Server (NTRS)

Chapman, G. L.; Jung, E. A.; Lewis, R. N.; Van Loon, L. S.; Welter, L. M.

1969-01-01

Scanning microscope uses a field-emission tip for the electron source, an electron gun that simultaneously accelerates and focuses electrons from the source, and one auxiliary lens to produce a final probe size at the specimen on the order of angstroms.

Proposed alteration of images of molecular orbitals obtained using a scanning tunneling microscope as a probe of electron correlation.

PubMed

Toroz, Dimitrios; Rontani, Massimo; Corni, Stefano

2013-01-04

Scanning tunneling spectroscopy (STS) allows us to image single molecules decoupled from the supporting substrate. The obtained images are routinely interpreted as the square moduli of molecular orbitals, dressed by the mean-field electron-electron interaction. Here we demonstrate that the effect of electron correlation beyond the mean field qualitatively alters the uncorrelated STS images. Our evidence is based on the ab initio many-body calculation of STS images of planar molecules with metal centers. We find that many-body correlations alter significantly the image spectral weight close to the metal center of the molecules. This change is large enough to be accessed experimentally, surviving to molecule-substrate interactions.

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

NASA Technical Reports Server (NTRS)

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

1975-01-01

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

Thermal-Wave Microscope

NASA Technical Reports Server (NTRS)

Jones, Robert E.; Kramarchuk, Ihor; Williams, Wallace D.; Pouch, John J.; Gilbert, Percy

1989-01-01

Computer-controlled thermal-wave microscope developed to investigate III-V compound semiconductor devices and materials. Is nondestructive technique providing information on subsurface thermal features of solid samples. Furthermore, because this is subsurface technique, three-dimensional imaging also possible. Microscope uses intensity-modulated electron beam of modified scanning electron microscope to generate thermal waves in sample. Acoustic waves generated by thermal waves received by transducer and processed in computer to form images displayed on video display of microscope or recorded on magnetic disk.

Microstructural evolution and micromechanical properties of gamma-irradiated Au ball bonds

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

Yusoff, Wan Yusmawati Wan, E-mail: yusmawati@upnm.edu.my; Ismail, Roslina, E-mail: roslina.ismail@ukm.my; Jalar, Azman, E-mail: azmn@ukm.my

2014-07-01

The effect of gamma radiation on the mechanical and structural properties of gold ball bonds was investigated. Gold wires from thermosonic wire bonding were exposed to gamma rays from a Cobalt-60 source at a low dose (5 Gy). The load–depth curve of nanoindentation for the irradiated gold wire bond has an apparent staircase shape during loading compared to the as-received sample. The hardness of the specimens calculated from the nanoindentation shows an increase in value from 0.91 to 1.09 GPa for specimens after exposure. The reduced elastic modulus for irradiated specimens significantly increased as well, with values from 75.18 tomore » 98.55 GPa. The change in intrinsic properties due to gamma radiation was investigated using dual-focused ion beam and high-resolution transmission electron microscope analysis. The dual-focused ion beam and high-resolution transmission electron microscope images confirmed the changes in grain structure and the presence of dislocations. The scanning electron microscope micrographs of focused ion beam cross sections showed that the grain structure of the gold became elongated and smaller after exposure to gamma rays. Meanwhile, high-resolution transmission electron microscopy provided evidence that gamma radiation induced dislocation of the atomic arrangement. - Highlights: • Nanoindentation technique provides a detailed characterisation of Au ball bond. • P–h curve of irradiated Au ball bond shows an apparent pop-in event. • Hardness and reduced modulus increased after exposure. • Elongated and smaller grain structure in irradiated specimens • Prevalent presence of dislocations in the atomic arrangement.« less

Morphoscopic analysis of experimentally produced bony wounds from low-velocity ballistic impact.

PubMed

Kieser, Jules A; Tahere, Joy; Agnew, Caitlin; Kieser, David C; Duncan, Warwick; Swain, Michael V; Reeves, Matthew T

2011-12-01

Understanding how bone behaves when subjected to ballistic impact is of critical importance for forensic questions, such as the reconstruction of shooting events. Yet the literature addressing microscopic anatomical features of gunshot wounds to different types of bone is sparse. Moreover, a biomechanical framework for describing how the complex architecture of bone affects its failure during such impact is lacking. The aim of this study was to examine the morphological features associated with experimental gunshot wounds in slaughtered pig ribs. We shot the 4th rib of 12 adult pigs with .22 mm subsonic bullets at close range (5 cm) and examined resultant wounds under the light microscope, scanning electron microscope SEM and micro tomograph μCT. In all cases there was a narrow shot channel followed by spall region, with evidence of plastic deformation with burnishing of the surface bone in the former, and brittle fracture around and through individual Haversian systems in the latter. In all but one case, the entrance wounds were characterized by superficially fractured cortical bone in the form of a well-defined collar, while the exit wounds showed delamination of the periosteum. Inorganic residue was evident in all cases, with electron energy dispersive spectroscopy EDS confirming the presence of carbon, phosphate, lead and calcium. This material appeared to be especially concentrated within the fractured bony collar at the entrance. We conclude that gunshot wounds in flat bones may be morphologically divided into a thin burnished zone at the entry site, and a fracture zone at the exit.

Nanometres-resolution Kikuchi patterns from materials science specimens with transmission electron forward scatter diffraction in the scanning electron microscope.

PubMed

Brodusch, N; Demers, H; Gauvin, R

2013-04-01

A charge-coupled device camera of an electron backscattered diffraction system in a scanning electron microscope was positioned below a thin specimen and transmission Kikuchi patterns were collected. Contrary to electron backscattered diffraction, transmission electron forward scatter diffraction provides phase identification and orientation mapping at the nanoscale. The minimum Pd particle size for which a Kikuchi diffraction pattern was detected and indexed reliably was 5.6 nm. An orientation mapping resolution of 5 nm was measured at 30 kV. The resolution obtained with transmission electron forward scatter diffraction was of the same order of magnitude than that reported in electron nanodiffraction in the transmission electron microscope. An energy dispersive spectrometer X-ray map and a transmission electron forward scatter diffraction orientation map were acquired simultaneously. The high-resolution chemical, phase and orientation maps provided at once information on the chemical form, orientation and coherency of precipitates in an aluminium-lithium 2099 alloy. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

Structural, optical and compositional stability of MoS2 multi-layer flakes under high dose electron beam irradiation

NASA Astrophysics Data System (ADS)

Rotunno, E.; Fabbri, F.; Cinquanta, E.; Kaplan, D.; Longo, M.; Lazzarini, L.; Molle, A.; Swaminathan, V.; Salviati, G.

2016-06-01

MoS2 multi-layer flakes, exfoliated from geological molybdenite, have been exposed to high dose electron irradiation showing clear evidence of crystal lattice and stoichiometry modifications. A massive surface sulfur depletion is induced together with the consequent formation of molybdenum nanoislands. It is found that a nanometric amorphous carbon layer, unwillingly deposited during the transmission electron microscope experiments, prevents the formation of the nanoislands. In the absence of the carbon layer, the formation of molybdenum grains proceeds both on the top and bottom surfaces of the flake. If carbon is present on both the surfaces then the formation of Mo grains is completely prevented.

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

NASA Astrophysics Data System (ADS)

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

2018-01-01

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

Pop-cola acids and tooth erosion: an in vitro, in vivo, electron-microscopic, and clinical report.

PubMed

Borjian, Amirfirooz; Ferrari, Claudia C F; Anouf, Antoni; Touyz, Louis Z G

2010-01-01

Introduction. Manufactured Colas are consumed universally as soft drinks. Evidence about the acid contents of Cola-beverages and its effects on teeth is rare. Aim. To assess (i) cola acidity and buffering capacity in vitro, (ii) tooth erosion after swishing with colas in vivo (iii) scanning electron microscopic effects on teeth of colas, and tooth-brush abrasion, and (iv) report a clinical case of erosion from cola consumption. Materials and Methods. (i) We measured six commercially available pop "Cola beverages", pH, and buffering capacities using a pH-Mettler Automatic Titrator, with weak solution of Sodium Hydroxide (ii) two cohorts, one with teeth, the second without teeth rinsed with aliquots of Cola for 60 seconds. Swished cola samples tested for calcium and phosphorus contents using standardized chemical analytical methods (iii) enamel, dentine, and the enamel-cemental junction from unerupted extracted wisdom teeth were examined with a scanning electron microscope after exposure to colas, and tested for tooth-brush abrasion; (iv) a clinical case of pop cola erosion presentation, are all described. Results. Comparisons among pop colas tested in vitro reveal high acidity with very low pH. Buffering capacities in millilitres of 0.5 M NaOH needed to increase one pH unit, to pH 5.5 and pH 7 are reported. Rinsing in vivo with pop cola causes leeching of calcium from teeth; SEM shows dental erosion, and pop-cola consumption induces advanced dental erosion and facilitates abrasion. Conclusions. (i) Pop-Cola acid activity is below the critical pH 5.5 for tooth dissolution, with high buffering capacities countering neutralization effects of saliva; (ii) calcium is leeched out of teeth after rinsing with pop colas; (iii) SEM evidence explains why chronic exposure to acid pop colas causes dental frangibles; (iv) a clinical case of pop-cola erosion confirms this.

Pop-Cola Acids and Tooth Erosion: An In Vitro, In Vivo, Electron-Microscopic, and Clinical Report

PubMed Central

Borjian, Amirfirooz; Ferrari, Claudia C. F.; Anouf, Antoni; Touyz, Louis Z. G.

2010-01-01

Introduction. Manufactured Colas are consumed universally as soft drinks. Evidence about the acid contents of Cola-beverages and its effects on teeth is rare. Aim. To assess (i) cola acidity and buffering capacity in vitro, (ii) tooth erosion after swishing with colas in vivo (iii) scanning electron microscopic effects on teeth of colas, and tooth-brush abrasion, and (iv) report a clinical case of erosion from cola consumption. Materials and Methods. (i) We measured six commercially available pop “Cola beverages”, pH, and buffering capacities using a pH-Mettler Automatic Titrator, with weak solution of Sodium Hydroxide (ii) two cohorts, one with teeth, the second without teeth rinsed with aliquots of Cola for 60 seconds. Swished cola samples tested for calcium and phosphorus contents using standardized chemical analytical methods (iii) enamel, dentine, and the enamel-cemental junction from unerupted extracted wisdom teeth were examined with a scanning electron microscope after exposure to colas, and tested for tooth-brush abrasion; (iv) a clinical case of pop cola erosion presentation, are all described. Results. Comparisons among pop colas tested in vitro reveal high acidity with very low pH. Buffering capacities in millilitres of 0.5 M NaOH needed to increase one pH unit, to pH 5.5 and pH 7 are reported. Rinsing in vivo with pop cola causes leeching of calcium from teeth; SEM shows dental erosion, and pop-cola consumption induces advanced dental erosion and facilitates abrasion. Conclusions. (i) Pop-Cola acid activity is below the critical pH 5.5 for tooth dissolution, with high buffering capacities countering neutralization effects of saliva; (ii) calcium is leeched out of teeth after rinsing with pop colas; (iii) SEM evidence explains why chronic exposure to acid pop colas causes dental frangibles; (iv) a clinical case of pop-cola erosion confirms this. PMID:21151663

Underbody Blast Models of TBI Caused by Hyper-Acceleration and Secondary Head Impact

DTIC Science & Technology

2014-02-01

Cleveland RO, Tanzi RE, Stanton PK, McKee AC. (2012) Chronic traumatic encephalopathy in blast-exposed military veterans and a blast neurotrauma mouse model...exposure, remove brains, and process for electron microscopic analysis of cyto- and axonal ultrastructure and for histochemical evidence of acute ...of Trauma and Acute Care Surgery (see Appendix). These observations include increased axonopathy (silver staining) in the cerebellum and astrocyte

PHOTOMETRIC EVIDENCE FOR THE OSMOTIC BEHAVIOR OF RAT LIVER MICROSOMES

PubMed Central

Tedeschi, Henry; James, Joseph M.; Anthony, William

1963-01-01

Electron microscope observations are consistent with the interpretation that the elements of the endoplasmic reticulum are osmotically active in situ as well as after isolation. More recently, it has been reported that microsomal suspensions equilibrate almost completely with added C14-sucrose and that no osmotic behavior is evident from photometric data. These findings were considered at variance with the electron microscope data. However, equilibration with added label simply attests to a relatively high permeability, and, in addition, the photometric data need not be critical. Osmotic volume changes, measured photometrically, may be masked by concomitant events (e.g., changes in the refractive index of the test solutions at varying osmotic pressures, breakdown of the particles, and agglutination). For these reasons the photometric experiments were repeated. In this work, the reciprocal of optical density of microsomal suspensions was found to vary linearly with the reciprocal of concentration of the medium at constant refractive index. These changes probably correspond to osmotic volume changes, since the effect was found to be (a) independent of substance used and (b) osmotically reversible. The transmission of the suspension was found to vary with the refractive index of the medium, the concentration of particles, and the wavelength of incident light, according to relationships that are similar to or identical with those obtained for mitochondrial suspensions. PMID:14064105

Comparative evaluation of enamel abrasivity by toothbrush and velcro: An in vitro scanning electron microscope study

PubMed Central

Ojha, Saroj Kumar; Javdekar, Sadashiv Bhaskar; Dhir, Sangeeta

2015-01-01

Context: Plaque control has been shown to be pivotal in maintaining the optimal periodontal health. Mechanical plaque control is the most popular option for establishing the optimal oral health. Toothbrushes have been the novel tool for mechanical cleansing. However, the abrasive potential of the toothbrushes on the enamel surface is an area in gray. Aims: The aim of this in vitro study is to evaluate the abrasivity of the toothbrush versus the velcro fasteners. Materials and Methods: The mounted teeth of both the groups were subjected to abrasion test, and the tooth surfaces were observed for the possible abrasions from the oscillating strokes (toothbrush) and frictional contacts (hook and loop velcro) and examined under the scanning electron microscope. Results: Comparative assessment of both velcro (hook and loop) and toothbrush bristles did not reveal any evidence of abrasion on the tooth specimens. Conclusions: Veclro fasteners are safe and qualitatively at par to the manual toothbrush for their efficacy and efficiency in teeth cleansing PMID:26229264

Dopant concentration dependent growth of Fe:ZnO nanostructures

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

Sahai, Anshuman; Goswami, Navendu, E-mail: navendugoswami@gmail.com

2016-05-23

Systematic investigations of structural properties of 1-10% Fe doped ZnO nanostructure (Fe:ZnO NS) prepared via chemical precipitation method have been reported. Structural properties were probed thoroughly employing scanning electron microscope (SEM) and transmission electron microscope (TEM), energy dispersive X-ray (EDAX) analysis and X-ray diffraction (XRD). Morphological transformation of nanostructures (NS) with Fe incorporation is evident in SEM/TEM images. Nanoparticles (NP) obtained with 1% Fe, evolve to nanorods (NR) for 3% Fe; NR transform to nanocones (NC) (for 5% and 7% Fe) and finally NC transform to nanoflakes (NF) at 10% Fe. Morover, primary phase of Zn{sub 1-x}Fe{sub x}O along withmore » secondary phases of ZnFe{sub 2}O{sub 4} and Fe{sub 2}O{sub 3} were also revealed through XRD measurements. Based on collective XRD, SEM, TEM, and EDAX interpretations, a model for morphological evolution of NS was proposed and the pivotal role of Fe dopant was deciphered.« less

Towards native-state imaging in biological context in the electron microscope

PubMed Central

Weston, Anne E.; Armer, Hannah E. J.

2009-01-01

Modern cell biology is reliant on light and fluorescence microscopy for analysis of cells, tissues and protein localisation. However, these powerful techniques are ultimately limited in resolution by the wavelength of light. Electron microscopes offer much greater resolution due to the shorter effective wavelength of electrons, allowing direct imaging of sub-cellular architecture. The harsh environment of the electron microscope chamber and the properties of the electron beam have led to complex chemical and mechanical preparation techniques, which distance biological samples from their native state and complicate data interpretation. Here we describe recent advances in sample preparation and instrumentation, which push the boundaries of high-resolution imaging. Cryopreparation, cryoelectron microscopy and environmental scanning electron microscopy strive to image samples in near native state. Advances in correlative microscopy and markers enable high-resolution localisation of proteins. Innovation in microscope design has pushed the boundaries of resolution to atomic scale, whilst automatic acquisition of high-resolution electron microscopy data through large volumes is finally able to place ultrastructure in biological context. PMID:19916039

Purchase of a Transmission Electron Microscope for Xavier University of Louisiana

DTIC Science & Technology

2015-05-15

imaging facility on the second floor of the Pharmacy Addition at Xavier University that already includes two scanning electron microscopes. The new TEM...is now in use. Xavier University has formally pledged to provide funds for the 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13. SUPPLEMENTARY...for Public Release; Distribution Unlimited Final Report: Purchase of a Transmission Electron Microscope for Xavier University of Louisiana The views

[Authentication of Trace Material Evidence in Forensic Science Field with Infrared Microscopic Technique].

PubMed

Jiang, Zhi-quan; Hu, Ke-liang

2016-03-01

In the field of forensic science, conventional infrared spectral analysis technique is usually unable to meet the detection requirements, because only very a few trace material evidence with diverse shapes and complex compositions, can be extracted from the crime scene. Infrared microscopic technique is developed based on a combination of Fourier-transform infrared spectroscopic technique and microscopic technique. Infrared microscopic technique has a lot of advantages over conventional infrared spectroscopic technique, such as high detection sensitivity, micro-area analysisand nondestructive examination. It has effectively solved the problem of authentication of trace material evidence in the field of forensic science. Additionally, almost no external interference is introduced during measurements by infrared microscopic technique. It can satisfy the special need that the trace material evidence must be reserved for witness in court. It is illustrated in detail through real case analysis in this experimental center that, infrared microscopic technique has advantages in authentication of trace material evidence in forensic science field. In this paper, the vibration features in infrared spectra of material evidences, including paints, plastics, rubbers, fibers, drugs and toxicants, can be comparatively analyzed by means of infrared microscopic technique, in an attempt to provide powerful spectroscopic evidence for qualitative diagnosis of various criminal and traffic accident cases. The experimental results clearly suggest that infrared microscopic technique has an incomparable advantage and it has become an effective method for authentication of trace material evidence in the field of forensic science.

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

PubMed

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

1976-10-01

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

Electron Microscope Center Opens at Berkeley.

ERIC Educational Resources Information Center

Robinson, Arthur L.

1981-01-01

A 1.5-MeV High Voltage Electron Microscope has been installed at the Lawrence Berkeley Laboratory which will help materials scientists and biologists study samples in more true-to-life situations. A 1-MeV Atomic Resolution Microscope will be installed at the same location in two years which will allow scientists to distinguish atoms. (DS)

Specimen Holder for Analytical Electron Microscopes

NASA Technical Reports Server (NTRS)

Clanton, U. S.; Isaacs, A. M.; Mackinnon, I.

1985-01-01

Reduces spectral contamination by spurious X-ray. Specimen holder made of compressed carbon, securely retains standard electron microscope grid (disk) 3 mm in diameter and absorbs backscattered electrons that otherwise generate spurious X-rays. Since holder inexpensive, dedicated to single specimen when numerous samples examined.

Fatal acute babesiosis in a juvenile wild dog (Lycaon pictus).

PubMed

Colly, L P; Nesbit, J W

1992-03-01

Clinical examination of a 75-day-old captive juvenile wild dog suffering from lassitude revealed pale mucous membranes, icterus, laboured respiration, a "water-hammer" pulse and splenomegaly. A peripheral blood smear containing numerous Babesia-infected erythrocytes confirmed the diagnosis of babesiosis. Treatment was unsuccessful and the animal died shortly after receiving a blood transfusion. The findings at necropsy were typical for acute babesiosis and included anaemia, icterus, splenomegaly and haemoglobinuria. In addition, marked atrophy of the thymus and lymph nodes was evident. Microscopic and electron microscopic examination of selected tissues disclosed high parasitaemia with vascular stasis and injury to both endothelial and parenchymal components. It is speculated that vaccination-induced immune incompetence predisposed to development of clinical babesiosis.

Microscope and method of use

DOEpatents

Bongianni, Wayne L.

1984-01-01

A method and apparatus for electronically focusing and electronically scanning microscopic specimens are given. In the invention, visual images of even moving, living, opaque specimens can be acoustically obtained and viewed with virtually no time needed for processing (i.e., real time processing is used). And planar samples are not required. The specimens (if planar) need not be moved during scanning, although it will be desirable and possible to move or rotate nonplanar specimens (e.g., laser fusion targets) against the lens of the apparatus. No coupling fluid is needed, so specimens need not be wetted. A phase acoustic microscope is also made from the basic microscope components together with electronic mixers.

Simultaneous specimen and stage cleaning device for analytical electron microscope

DOEpatents

Zaluzec, Nestor J.

1996-01-01

An improved method and apparatus are provided for cleaning both a specimen stage, a specimen and an interior of an analytical electron microscope (AEM). The apparatus for cleaning a specimen stage and specimen comprising a plasma chamber for containing a gas plasma and an air lock coupled to the plasma chamber for permitting passage of the specimen stage and specimen into the plasma chamber and maintaining an airtight chamber. The specimen stage and specimen are subjected to a reactive plasma gas that is either DC or RF excited. The apparatus can be mounted on the analytical electron microscope (AEM) for cleaning the interior of the microscope.

Microscope and method of use

DOEpatents

Bongianni, W.L.

1984-04-17

A method and apparatus for electronically focusing and electronically scanning microscopic specimens are given. In the invention, visual images of even moving, living, opaque specimens can be acoustically obtained and viewed with virtually no time needed for processing (i.e., real time processing is used). And planar samples are not required. The specimens (if planar) need not be moved during scanning, although it will be desirable and possible to move or rotate nonplanar specimens (e.g., laser fusion targets) against the lens of the apparatus. No coupling fluid is needed, so specimens need not be wetted. A phase acoustic microscope is also made from the basic microscope components together with electronic mixers. 7 figs.

Development of a SEM-based low-energy in-line electron holography microscope for individual particle imaging.

PubMed

Adaniya, Hidehito; Cheung, Martin; Cassidy, Cathal; Yamashita, Masao; Shintake, Tsumoru

2018-05-01

A new SEM-based in-line electron holography microscope has been under development. The microscope utilizes conventional SEM and BF-STEM functionality to allow for rapid searching of the specimen of interest, seamless interchange between SEM, BF-STEM and holographic imaging modes, and makes use of coherent low-energy in-line electron holography to obtain low-dose, high-contrast images of light element materials. We report here an overview of the instrumentation and first experimental results on gold nano-particles and carbon nano-fibers for system performance tests. Reconstructed images obtained from the holographic imaging mode of the new microscope show substantial image contrast and resolution compared to those acquired by SEM and BF-STEM modes, demonstrating the feasibility of high-contrast imaging via low-energy in-line electron holography. The prospect of utilizing the new microscope to image purified biological specimens at the individual particle level is discussed and electron optical issues and challenges to further improve resolution and contrast are considered. Copyright © 2018 Elsevier B.V. All rights reserved.

Kidney lesions in Rocky Mountain spotted fever: a light-, immunofluorescence-, and electron-microscopic study.

PubMed Central

Bradford, W. D.; Croker, B. P.; Tisher, C. C.

1979-01-01

The essential pathologic lesion in Rocky Mountain spotted fever (RMSF) is a vasculitis that may involve the kidneys as well as the heart, brain, skin, and subcutaneous tissues. Histopathologic information concerning the response of the kidneys in RMSF is rather limited, however. In this study renal tissue from 17 children who died of RMSF was examined by light, electron, and immunofluorescence microscopy. A lymphocytic or mixed inflammation, or both, involving vessels and interstitium of the kidney was found in all patients. In addition, 10 patients had histologic evidence of acute tubular necrosis, and another 3 had glomerular lesions consisting of focal segmental tuft necrosis or increased cellularity secondary to neutophilic infiltration, or both. Immunofluorescence- and electron-microscopic studies failed to demonstrate immune-complex deposition within glomeruli, a finding that suggests that immunoglobulin and classic immune complexes were not involved in the pathogenesis of the renal lesions at the time of death. These findings suggest the possibility that the pathogenesis of the renal lesion in RMSF may be due to a direct action of the organism (Rickettsia rickettsii) on the vessel wall. Images Figure 2 Figure 1 PMID:525676

High-efficiency and conveniently recyclable photo-catalysts for dye degradation based on urchin-like CuO microparticle/polymer hybrid composites

NASA Astrophysics Data System (ADS)

Liu, Xiong; Cheng, Yuming; Li, Xuefeng; Dong, Jinfeng

2018-05-01

In this work, we developed a new type of photo-catalysts composed of the urchin-like cupric oxide (CuO) microparticle and polyvinylidene fluoride (PVDF) hybrid composites by the convenient organic-inorganic hybrid strategy, which show high-efficiency and conveniently recyclable for dye degradation including methylene blue (MB), Congo red (CR), and malachite green (MG) by visible light irradiation. The micro-structural characteristics of urchin-like CuO microparticles are crucial and dominant over the photo-degrading efficiency of hybrid catalyst because of their highly exposed {0 0 2} facet and larger specific surface area. Simultaneously, the intrinsic porous framework of PVDF membrane not only remains the excellent photo-catalytic activity of urchin-like CuO microparticles but also facilitates the enrichment of dyes on the membrane, and thereby synergistically contributing to the photo-catalytic efficiency. The microstructures of both urchin-like CuO microparticles and hybrid catalysts are systematically characterized by various techniques including scanning electron microscopy (SEM), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and nitrogen adsorption/desorption isotherms, which evidently support the mentioned mechanism.

Nitrogen implantation with a scanning electron microscope.

PubMed

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

2018-01-08

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

75 FR 43918 - National Center for Toxicological Research, et al.; Notice of Consolidated Decision on...

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2010-07-27

... Research, et al.; Notice of Consolidated Decision on Applications for Duty-Free Entry of Electron...: National Center for Toxicological Research, (USFDA), Jefferson, AK 72079. Instrument: Electron Microscope.... Applicant: University of Virginia, Charlottesville, VA 22903. Instrument: Electron Microscope. Manufacturer...

Scanning Electron Microscope Observations of Marine Microorganisms on Surfaces Coated with Antifouling Paints.

DTIC Science & Technology

1981-06-01

sessile marine inverte- brates in Monterey harbor. Veliger 17 (supplement): 1-35. 1977. The nature of primary organic films in the marine environment and...I A10A4h 605 NAVAL POSTGRADUATE SCHOOL MONTEREY CA F/S 11/3 SCANING ELECTRON MICROSCOPE OBSERVATIONS OF MARINE MICROORANI-E-C(U) UNLSSIFIED N*2...Scanning Electron Microscope Observations Master’s thesis; of Marine Microorganisms on Surfaces June 1981 Coated with Ant ifouling Paints 6.PERFORMING

Electron microscope aperture system

NASA Technical Reports Server (NTRS)

Heinemann, K. (Inventor)

1976-01-01

An electron microscope including an electron source, a condenser lens having either a circular aperture for focusing a solid cone of electrons onto a specimen or an annular aperture for focusing a hollow cone of electrons onto the specimen, and an objective lens having an annular objective aperture, for focusing electrons passing through the specimen onto an image plane are described. The invention also entails a method of making the annular objective aperture using electron imaging, electrolytic deposition and ion etching techniques.

Choice and maintenance of equipment for electron crystallography.

PubMed

Mills, Deryck J; Vonck, Janet

2013-01-01

The choice of equipment for an electron crystallography laboratory will ultimately be determined by the available budget; nevertheless, the ideal lab will have two electron microscopes: a dedicated 300 kV cryo-EM with a field emission gun and a smaller LaB(6) machine for screening. The high-end machine should be equipped with photographic film or a very large CCD or CMOS camera for 2D crystal data collection; the screening microscope needs a mid-size CCD for rapid evaluation of crystal samples. The microscope room installations should provide adequate space and a special environment that puts no restrictions on the collection of high-resolution data. Equipment for specimen preparation includes a carbon coater, glow discharge unit, light microscope, plunge freezer, and liquid nitrogen containers and storage dewars. When photographic film is to be used, additional requirements are a film desiccator, dark room, optical diffractometer, and a film scanner. Having the electron microscopes and ancillary equipment well maintained and always in optimum condition facilitates the production of high-quality data.

Vibrational spectroscopy in the electron microscope.

PubMed

Krivanek, Ondrej L; Lovejoy, Tracy C; Dellby, Niklas; Aoki, Toshihiro; Carpenter, R W; Rez, Peter; Soignard, Emmanuel; Zhu, Jiangtao; Batson, Philip E; Lagos, Maureen J; Egerton, Ray F; Crozier, Peter A

2014-10-09

Vibrational spectroscopies using infrared radiation, Raman scattering, neutrons, low-energy electrons and inelastic electron tunnelling are powerful techniques that can analyse bonding arrangements, identify chemical compounds and probe many other important properties of materials. The spatial resolution of these spectroscopies is typically one micrometre or more, although it can reach a few tens of nanometres or even a few ångströms when enhanced by the presence of a sharp metallic tip. If vibrational spectroscopy could be combined with the spatial resolution and flexibility of the transmission electron microscope, it would open up the study of vibrational modes in many different types of nanostructures. Unfortunately, the energy resolution of electron energy loss spectroscopy performed in the electron microscope has until now been too poor to allow such a combination. Recent developments that have improved the attainable energy resolution of electron energy loss spectroscopy in a scanning transmission electron microscope to around ten millielectronvolts now allow vibrational spectroscopy to be carried out in the electron microscope. Here we describe the innovations responsible for the progress, and present examples of applications in inorganic and organic materials, including the detection of hydrogen. We also demonstrate that the vibrational signal has both high- and low-spatial-resolution components, that the first component can be used to map vibrational features at nanometre-level resolution, and that the second component can be used for analysis carried out with the beam positioned just outside the sample--that is, for 'aloof' spectroscopy that largely avoids radiation damage.

Ultrastructural Study of Some Pollen Grains of Prairie Flowers

ERIC Educational Resources Information Center

Kozar, Frank

1973-01-01

Discusses the importance of the electron microscope, and in particular the scanning electron microscope, in studying the surface topography, sectional substructures, and patterns of development of pollen grains. The production, dispersal methods, and structure of pollen grains are described and illustrated with numerous electron micrographs. (JR)

Synthesis Properties and Electron Spin Resonance Properties of Titanic Materials (abstract)

NASA Astrophysics Data System (ADS)

Cho, Jung Min; Lee, Jun; Kim, Tak Hee; Sun, Min Ho; Jang, Young Bae; Cho, Sung June

2009-04-01

Titanic materials were synthesized by hydrothermal method of TiO2 anatase in 10M LiOH, 10M NaOH, and 14M KOH at 130° C for 30 hours. Alkaline media were removed from the synthesized products using 0.1N HCl aqueous solution. The as-prepared samples were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, Brunauer-Emmett-Teller isotherm, and electron spin resonance. Different shapes of synthesized products were observed through the typical electron microscope and indicated that the formation of the different morphologies depends on the treatment conditions of highly alkaline media. Many micropores were observed in the cubic or octahedral type of TiO2 samples through the typical electron microscope and Langmuir adsorption-desorption isotherm of liquid nitrogen at 77° K. Electron spin resonance studies have also been carried out to verify the existence of paramagnetic sites such as oxygen vacancies on the titania samples. The effect of alkali metal ions on the morphologies and physicochemical properties of nanoscale titania are discussed.

Design and performance of a beetle-type double-tip scanning tunneling microscope

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

Jaschinsky, Philipp; Coenen, Peter; Pirug, Gerhard

2006-09-15

A combination of a double-tip scanning tunneling microscope with a scanning electron microscope in ultrahigh vacuum environment is presented. The compact beetle-type design made it possible to integrate two independently driven scanning tunneling microscopes in a small space. Moreover, an additional level for coarse movement allows the decoupling of the translation and approach of the tunneling tip. The position of the two tips can be controlled from the millimeter scale down to 50 nm with the help of an add-on electron microscope. The instrument is capable of atomic resolution imaging with each tip.

Development of Scanning Ultrafast Electron Microscope Capability.

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

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

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

Multifarious applications of atomic force microscopy in forensic science investigations.

PubMed

Pandey, Gaurav; Tharmavaram, Maithri; Rawtani, Deepak; Kumar, Sumit; Agrawal, Y

2017-04-01

Forensic science is a wide field comprising of several subspecialties and uses methods derived from natural sciences for finding criminals and other evidence valid in a legal court. A relatively new area; Nano-forensics brings a new era of investigation in forensic science in which instantaneous results can be produced that determine various agents such as explosive gasses, biological agents and residues in different crime scenes and terrorist activity investigations. This can be achieved by applying Nanotechnology and its associated characterization techniques in forensic sciences. Several characterization techniques exist in Nanotechnology and nano-analysis is one such technique that is used in forensic science which includes Electron microscopes (EM) like Transmission (TEM) and Scanning (SEM), Raman microscopy (Micro -Raman) and Scanning Probe Microscopes (SPMs) like Atomic Force Microscope (AFM). Atomic force microscopy enables surface characterization of different materials by examining their morphology and mechanical properties. Materials that are immeasurable such as hair, body fluids, textile fibers, documents, polymers, pressure sensitive adhesives (PSAs), etc. are often encountered during forensic investigations. This review article will mainly focus on the use of AFM in the examination of different evidence such as blood stains, forged documents, human hair samples, ammunitions, explosives, and other such applications in the field of Forensic Science. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultrastructure of cholinergic neurons in the laterodorsal tegmental nucleus of the rat: interaction with catecholamine fibers.

PubMed

Kubota, Y; Leung, E; Vincent, S R

1992-01-01

The ultrastructure of choline acetyltransferase (ChAT)-immunoreactive neurons in the laterodorsal tegmental nucleus (TLD) of the rat was investigated by immunohistochemical techniques. The immunoreactive neurons were medium to large in size, with a few elongated dendrites, contained well-developed cytoplasm, and a nucleus with deep infoldings. They received many nonimmunoreactive, mostly asymmetric synaptic inputs on their soma and dendrites. ChAT-immunoreactive, usually myelinated, axons were occasionally seen in TLD. Only one immunoreactive axon terminal was observed within TLD, and it made synaptic contact with a nonimmunoreactive neuronal perikaryon. The synaptic interactions between ChAT-immunoreactive neurons and tyrosine hydroxylase (TH)-immunoreactive fibers in the TLD were investigated with a double immunohistochemical staining method. ChAT-immunoreactivity detected with a beta-galactosidase method was light blue-green in the light microscope and formed dot-like electron dense particles at the electron microscopic level. TH-immunoreactivity, visualized with a nickel-enhanced immunoperoxidase method, was dark blue-black in the light microscope and diffusely opaque in the electron microscope. Therefore, the difference between these two kinds of immunoreactivity could be quite easily distinguished at both light and electron microscopic levels. In the light microscope, TH-positive fibers were often closely apposed to ChAT-immunoreactive cell bodies and dendrites in TLD. In the electron microscope, the cell soma and proximal dendrites of ChAT-immunoreactive neurons received synaptic contacts from TH-immunoreactive axon terminals. These results provide a morphological basis for catecholaminergic regulation of the cholinergic reticular system.

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2012-12-04

... Consolidated Decision on Applications for Duty-Free Entry of Electron Microscope This is a decision... Stocker Center, Athens, OH 45701. Instrument: Electron Microscope. Manufacturer: JEOL Ltd., Japan... North Carolina Wilmington, 601 South College Road, Wilmington, NC 28403-5915. Instrument: Electron...

Influence of mechanical noise inside a scanning electron microscope.

PubMed

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

2015-04-01

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

Microcircuit testing and fabrication, using scanning electron microscopes

NASA Technical Reports Server (NTRS)

Nicolas, D. P.

1975-01-01

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

Method of forming aperture plate for electron microscope

NASA Technical Reports Server (NTRS)

Heinemann, K. (Inventor)

1974-01-01

An electron microscope is described with an electron source a condenser lens having either a circular aperture for focusing a solid cone of electrons onto a specimen or an annular aperture for focusing a hollow cone of electrons onto the specimen. It also has objective lens with an annular objective aperture, for focusing electrons passing through the specimen onto an image plane. A method of making the annular objective aperture using electron imaging, electrolytic deposition and ion etching techniques is included.

Development of scanning electron and x-ray microscope

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

Matsumura, Tomokazu, E-mail: tomokzau.matsumura@etd.hpk.co.jp; Hirano, Tomohiko, E-mail: tomohiko.hirano@etd.hpk.co.jp; Suyama, Motohiro, E-mail: suyama@etd.hpk.co.jp

We have developed a new type of microscope possessing a unique feature of observing both scanning electron and X-ray images under one unit. Unlike former X-ray microscopes using SEM [1, 2], this scanning electron and X-ray (SELX) microscope has a sample in vacuum, thus it enables one to observe a surface structure of a sample by SEM mode, to search the region of interest, and to observe an X-ray image which transmits the region. For the X-ray observation, we have been focusing on the soft X-ray region from 280 eV to 3 keV to observe some bio samples and softmore » materials. The resolutions of SEM and X-ray modes are 50 nm and 100 nm, respectively, at the electron energy of 7 keV.« less

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

NASA Technical Reports Server (NTRS)

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

1972-01-01

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

Multi-pass transmission electron microscopy

DOE PAGES

Juffmann, Thomas; Koppell, Stewart A.; Klopfer, Brannon B.; ...

2017-05-10

Feynman once asked physicists to build better electron microscopes to be able to watch biology at work. While electron microscopes can now provide atomic resolution, electron beam induced specimen damage precludes high resolution imaging of sensitive materials, such as single proteins or polymers. Here, we use simulations to show that an electron microscope based on a multi-pass measurement protocol enables imaging of single proteins, without averaging structures over multiple images. While we demonstrate the method for particular imaging targets, the approach is broadly applicable and is expected to improve resolution and sensitivity for a range of electron microscopy imaging modalities,more » including, for example, scanning and spectroscopic techniques. The approach implements a quantum mechanically optimal strategy which under idealized conditions can be considered interaction-free.« less

Postnatal development of microcyst in the anteroventral cochlear nucleus of the Mongolian gerbil: a light- and electron microscopic study.

PubMed

Yu, Shang-Ming; Ko, Tsui-Ling; Lin, Kwan-Hwa

2011-09-01

We investigated the postnatal formation and origin of the microcyst, which are not fully elucidated at present, in the cochlear nucleus of gerbils. Sixty-six Mongolian gerbils were investigated at the light microscope level, and 35 of them were observed at the electron microscopic level. Foamy structures were evidently found at 2 days of age and remained unchanged through 4-8 days. The first small vacuole, presumably the former microcyst, appeared at 8 days. Myelin sheath bundles first appeared at 13 days. Electron-dense bodies were frequently found in the junction of the superficial layer and the deep layer at 2 days. The medium-sized vacuole was found in close association with the spherical bushy cells in the anteroventral cochlear nucleus (AVCN) as early as 5 weeks. Various large and small vacuoles were presumably coalesced to form a large vacuole at 3 and 6 months. Membranous structures and red blood cells were in the budding-like vacuoles at 6 months. In addition to membranous structures, the microcyst contained distorted mitochondria and parts of myelin sheaths. The vacuole was interposed between spherical bushy cells at age of 10 months. Small vacuoles were mainly located in the flame-shaped neurons at 14 months. An internal detachment and an external protrusion of the myelin sheath into the adjacent microcyst were found. Thus, this study suggests the first appearance of microcysts at 8 days. Also, the microcyst and the blood vessel may exchange their contents through a leakage in the anteroventral cochlear nucleus.

Measurement of flow speed in the channels of novel threadlike structures on the surfaces of mammalian organs

NASA Astrophysics Data System (ADS)

Sung, Baeckkyoung; Kim, Min Su; Lee, Byung-Cheon; Yoo, Jung Sun; Lee, Sang-Hee; Kim, Youn-Joong; Kim, Ki-Woo; Soh, Kwang-Sup

2008-02-01

There have been several reports on novel threadlike structures (NTSs) on the surfaces of the internal organs of rats and rabbits since their first observation by Bonghan Kim in 1963. To confirm this novel circulatory function, it is necessary to observe the flow of liquid through the NTS as well as the structurally corroborating channels in the NTS. In this article, we report on the measurement of the flow speed of Alcian blue solution in the NTSs on the organ surfaces of rabbits, and we present electron microscopic images depicting the cribrous cross-section with channels. The speed was measured as 0.3 ± 0.1 mm/s, and the flow distance was up to 12 cm. The flow was unidirectional, and the phase contrast microscopic images showed that the NTSs were strongly stained with Alcian blue. The ultrastructure of the NTSs revealed by cryo-scanning electron microscopy and high-voltage electron microscopy showed that (1) there were cell-like bodies and globular clumps of matter inside the sinus of the channel with thin strands of segregated zones which is a microscopic evidence of the liquid flow, (2) the sinuses have wall structures surrounded with extracellular matrices of collagenous fibers, and (3) there exists a cribriform structure of sinuses. To understand the mechanism for the circulation, a quantitative analysis of the flow speed has been undertaken applying a simplified windkessel model. In this analysis, it was shown that the liquid flow through the NTSs could be due to peristaltic motion of the NTS itself.

Visualizing Morphological Changes of Abscission Zone Cells in Arabidopsis by Scanning Electron Microscope.

PubMed

Shi, Chun-Lin; Butenko, Melinka A

2018-01-01

Scanning electron microscope (SEM) is a type of electron microscope which produces detailed images of surface structures. It has been widely used in plants and animals to study cellular structures. Here, we describe a detailed protocol to prepare samples of floral abscission zones (AZs) for SEM, as well as further image analysis. We show that it is a powerful tool to detect morphologic changes at the cellular level during the course of abscission in wild-type plants and to establish the details of phenotypic alteration in abscission mutants.

Scanning electron microscopic appearance of rat otocyst of the twelfth postcoital day: elaboration of a method.

PubMed

Marovitz, W F; Khan, K M

1977-01-01

A method for removal, fixation, microdissection, and drying of early rat otocyst for examination by the scanning electron microscope is elaborated. Tissues were dissected, fixed as for conventional transmission electron microscopy and dried by critical point evaporation using amylacetate as the transitional fluid and carbon dioxide as the pressure head. Otocysts were either dissected at the time of initial fixation, or subsequent to drying. The otocyst of the 12th postcoital day was used as a model system in this preliminary report. Critical point drying retained the overall configuration and the fine ultrastructural detail of the otocyst. The interior otocystic surface was visualized and cilia bearing cells of the luminal surface were identified. Most if not all of these cells had a comspicuous, but short kinocillum which terminated in an ovoid bulb. The scanning electron microscopic appearance was correlated to the transmission electron microscopic image seen in the second paper in this Supplement.

Atmospheric scanning electron microscope for correlative microscopy.

PubMed

Morrison, Ian E G; Dennison, Clare L; Nishiyama, Hidetoshi; Suga, Mitsuo; Sato, Chikara; Yarwood, Andrew; O'Toole, Peter J

2012-01-01

The JEOL ClairScope is the first truly correlative scanning electron and optical microscope. An inverted scanning electron microscope (SEM) column allows electron images of wet samples to be obtained in ambient conditions in a biological culture dish, via a silicon nitride film window in the base. A standard inverted optical microscope positioned above the dish holder can be used to take reflected light and epifluorescence images of the same sample, under atmospheric conditions that permit biochemical modifications. For SEM, the open dish allows successive staining operations to be performed without moving the holder. The standard optical color camera used for fluorescence imaging can be exchanged for a high-sensitivity monochrome camera to detect low-intensity fluorescence signals, and also cathodoluminescence emission from nanophosphor particles. If these particles are applied to the sample at a suitable density, they can greatly assist the task of perfecting the correlation between the optical and electron images. Copyright © 2012 Elsevier Inc. All rights reserved.

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

Juffmann, Thomas; Koppell, Stewart A.; Klopfer, Brannon B.

Feynman once asked physicists to build better electron microscopes to be able to watch biology at work. While electron microscopes can now provide atomic resolution, electron beam induced specimen damage precludes high resolution imaging of sensitive materials, such as single proteins or polymers. Here, we use simulations to show that an electron microscope based on a multi-pass measurement protocol enables imaging of single proteins, without averaging structures over multiple images. While we demonstrate the method for particular imaging targets, the approach is broadly applicable and is expected to improve resolution and sensitivity for a range of electron microscopy imaging modalities,more » including, for example, scanning and spectroscopic techniques. The approach implements a quantum mechanically optimal strategy which under idealized conditions can be considered interaction-free.« less

Electron holography study of magnetization behavior in the writer pole of a perpendicular magnetic recording head by a 1 MV transmission electron microscope.

PubMed

Hirata, Kei; Ishida, Yoichi; Akashi, Tetsuya; Shindo, Daisuke; Tonomura, Akira

2012-01-01

The magnetic domain structure of the writer poles of perpendicular magnetic recording heads was studied using electron holography. Although the domain structure of a 100-nm-thick writer pole could be observed with a 300 kV transmission electron microscope, that of the 250-nm-thick writer pole could not be analyzed due to the limited transmission capability of the instrument. On the other hand, the detailed domain structure of the 250-nm-thick writer pole was successfully analyzed by a 1 MV electron microscope using its high transmission capability. The thickness and material dependency of the domain structure of a writer pole were discussed.

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

PubMed

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

2018-02-01

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

Optics of high-performance electron microscopes*

PubMed Central

Rose, H H

2008-01-01

During recent years, the theory of charged particle optics together with advances in fabrication tolerances and experimental techniques has lead to very significant advances in high-performance electron microscopes. Here, we will describe which theoretical tools, inventions and designs have driven this development. We cover the basic theory of higher-order electron optics and of image formation in electron microscopes. This leads to a description of different methods to correct aberrations by multipole fields and to a discussion of the most advanced design that take advantage of these techniques. The theory of electron mirrors is developed and it is shown how this can be used to correct aberrations and to design energy filters. Finally, different types of energy filters are described. PMID:27877933

Widespread hydrothermal alteration minerals in the fine-grained matrices of the Tieschitz unequilibrated ordinary chondrite

NASA Astrophysics Data System (ADS)

Dobricǎ, E.; Brearley, A. J.

2014-08-01

Mineralogic, textural, and compositional studies of black and white matrices in the unequilibrated ordinary chondrite Tieschitz (H/L, 3.6) show, for the first time in an ordinary chondrite, the presence of widespread, randomly distributed geode-like voids and veins. Scanning electron microscope (SEM) and transmission electron microscope (TEM) studies show that these voids and veins are partially or completely filled by sodic-calcic amphiboles (winchite and barroisite). The occurrence of amphiboles provides unequivocal evidence of the involvement of fluids in the metamorphic evolution of the parent body of Tieschitz. The presence of amphiboles as the main hydrous phases, rather than phyllosilicates, indicates that aqueous fluids were present at or close to the peak of thermal metamorphism, rather than during the waning stages of the cooling history of the parent body. In addition, ferrous olivine crystals, in association with the amphibole, also establish an important link between thermal metamorphism and hydrous phases formed at high temperatures. Mineralogic and textural evidence suggests that the white matrix and amphibole formed contemporaneously from the same hydrous fluid, prior to the formation of ferrous olivine crystals. Additionally, a dark inclusion identified in the host chondrite has mineralogic, petrologic, and bulk chemical characteristics that are similar to the black matrix of host Tieschitz, suggesting that this dark inclusion was emplaced before or during parent body metamorphism.

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

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

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

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

NASA Technical Reports Server (NTRS)

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

1972-01-01

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

Removal of Micrometer Size Morphological Defects and Enhancement of Ultraviolet Emission by Thermal Treatment of Ga-Doped ZnO Nanostructures

PubMed Central

Manzoor, Umair; Kim, Do K.; Islam, Mohammad; Bhatti, Arshad S.

2014-01-01

Mixed morphologies of Ga-doped Zinc Oxide (ZnO) nanostructures are synthesized by vapor transport method. Systematic scanning electron microscope (SEM) studies of different morphologies, after periodic heat treatments, gives direct evidence of sublimation. SEM micrographs give direct evidence that morphological defects of nanostructures can be removed by annealing. Ultra Violet (UV) and visible emission depends strongly on the annealing temperatures and luminescent efficiency of UV emission is enhanced significantly with each subsequent heat treatment. X-Ray diffraction (XRD) results suggest that crystal quality improved by annealing and phase separation may occur at high temperatures. PMID:24489725

Removal of micrometer size morphological defects and enhancement of ultraviolet emission by thermal treatment of Ga-doped ZnO nanostructures.

PubMed

Manzoor, Umair; Kim, Do K; Islam, Mohammad; Bhatti, Arshad S

2014-01-01

Mixed morphologies of Ga-doped Zinc Oxide (ZnO) nanostructures are synthesized by vapor transport method. Systematic scanning electron microscope (SEM) studies of different morphologies, after periodic heat treatments, gives direct evidence of sublimation. SEM micrographs give direct evidence that morphological defects of nanostructures can be removed by annealing. Ultra Violet (UV) and visible emission depends strongly on the annealing temperatures and luminescent efficiency of UV emission is enhanced significantly with each subsequent heat treatment. X-Ray diffraction (XRD) results suggest that crystal quality improved by annealing and phase separation may occur at high temperatures.

Influence of mechanical noise inside a scanning electron microscope

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

Gaudenzi de Faria, Marcelo; Haddab, Yassine, E-mail: yassine.haddab@femto-st.fr; Le Gorrec, Yann

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 themore » 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.« less

Ionic liquid-based observation technique for nonconductive materials in the scanning electron microscope: Application to the characterization of a rare earth ore.

PubMed

Brodusch, Nicolas; Waters, Kristian; Demers, Hendrix; Gauvin, Raynald

2014-03-01

A new approach for preparing geological materials is proposed to reduce charging during their characterization in a scanning electron microscope. This technique was applied to a sample of the Nechalacho rare earth deposit, which contains a significant amount of the minerals fergusonite and zircon. Instead of covering the specimen surface with a conductive coating, the sample was immersed in a dilute solution of ionic liquid and then air dried prior to SEM analysis. Imaging at a wide range of accelerating voltages was then possible without evidence of charging when using the in-chamber secondary and backscattered electrons detectors, even at 1 kV. High resolution x-ray and electron backscatter diffraction mapping were successfully obtained at 20 and 5 kV with negligible image drifting and permitted the characterization of the microstructure of the zircon/fergusonite-Y aggregates encased in the matrix minerals. Because of the absence of a conductive layer at the surface of the specimen, the Kikuchi band contrast was improved and the backscatter electron signal increased at both 5 and 20 kV as confirmed by Monte Carlo modeling. These major developments led to an improvement of the spatial resolution and efficiency of the above characterization techniques applied to the rare earth ore and it is expected that they can be applied to other types of ores and minerals. Copyright © 2014 Wiley Periodicals, Inc.

78 FR 5776 - Columbia University, et al.; Notice of Consolidated Decision on Applications for Duty-Free Entry...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-28

... 94305. Instrument: Titan 80-300 Environmental Transmission Electron Microscope. Manufacturer: FEI Co.../Scanning Electron Microscope. Manufacturer: FEI Co., the Netherlands. Intended Use: See notice at 77 FR...

Fine needle aspiration (FNA) of synovial sarcoma--a comparative histological-cytological study of 15 cases, including immunohistochemical, electron microscopic and cytogenetic examination and DNA-ploidy analysis.

PubMed

Akerman, M; Willén, H; Carlén, B; Mandahl, N; Mertens, F

1996-06-01

A retrospective study of 25 FNAs (11 aspirates from primary tumours and 14 from recurrencies and metastases) from 15 synovial sarcomas was performed. The cytological findings were correlated with the histopathology and the value of immunohistochemical and electron microscopic examination as well as DNA-ploidy and cytogenetic analysis for diagnosis were assessed. A reproducible cellular pattern with a reliable diagnosis of spindle cell sarcoma was possible provided that the aspirates were cell rich. However, a true biphasic pattern indicative of synovial sarcoma was only seen in one of the 25 specimens. Electron microscopic examination of the aspirates was a valuable adjunctive diagnostic method, whereas immunocytochemistry and DNA-ploidy analysis were not. Immunohistochemical, electron microscopic and cytogenetic analysis were all valuable ancillary methods when performed on surgical specimens. Malignant haemangiopericytoma and fibrosarcoma were the most important differential diagnoses in the FNA specimens.

A two-dimensional Dirac fermion microscope

NASA Astrophysics Data System (ADS)

Bøggild, Peter; Caridad, José M.; Stampfer, Christoph; Calogero, Gaetano; Papior, Nick Rübner; Brandbyge, Mads

2017-06-01

The electron microscope has been a powerful, highly versatile workhorse in the fields of material and surface science, micro and nanotechnology, biology and geology, for nearly 80 years. The advent of two-dimensional materials opens new possibilities for realizing an analogy to electron microscopy in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2D electron guns, deflectors, tunable lenses and various detectors. The simulations show how simple objects can be imaged with well-controlled and collimated in-plane beams consisting of relativistic charge carriers. Finally, we discuss the potential of such microscopes for investigating edges, terminations and defects, as well as interfaces, including external nanoscale structures such as adsorbed molecules, nanoparticles or quantum dots.

A two-dimensional Dirac fermion microscope

PubMed Central

Bøggild, Peter; Caridad, José M.; Stampfer, Christoph; Calogero, Gaetano; Papior, Nick Rübner; Brandbyge, Mads

2017-01-01

The electron microscope has been a powerful, highly versatile workhorse in the fields of material and surface science, micro and nanotechnology, biology and geology, for nearly 80 years. The advent of two-dimensional materials opens new possibilities for realizing an analogy to electron microscopy in the solid state. Here we provide a perspective view on how a two-dimensional (2D) Dirac fermion-based microscope can be realistically implemented and operated, using graphene as a vacuum chamber for ballistic electrons. We use semiclassical simulations to propose concrete architectures and design rules of 2D electron guns, deflectors, tunable lenses and various detectors. The simulations show how simple objects can be imaged with well-controlled and collimated in-plane beams consisting of relativistic charge carriers. Finally, we discuss the potential of such microscopes for investigating edges, terminations and defects, as well as interfaces, including external nanoscale structures such as adsorbed molecules, nanoparticles or quantum dots. PMID:28598421

Scanning Microscopes Using X Rays and Microchannels

NASA Technical Reports Server (NTRS)

Wang, Yu

2003-01-01

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

Development of the field of structural physiology

PubMed Central

FUJIYOSHI, Yoshinori

2015-01-01

Electron crystallography is especially useful for studying the structure and function of membrane proteins — key molecules with important functions in neural and other cells. Electron crystallography is now an established technique for analyzing the structures of membrane proteins in lipid bilayers that closely simulate their natural biological environment. Utilizing cryo-electron microscopes with helium-cooled specimen stages that were developed through a personal motivation to understand the functions of neural systems from a structural point of view, the structures of membrane proteins can be analyzed at a higher than 3 Å resolution. This review covers four objectives. First, I introduce the new research field of structural physiology. Second, I recount some of the struggles involved in developing cryo-electron microscopes. Third, I review the structural and functional analyses of membrane proteins mainly by electron crystallography using cryo-electron microscopes. Finally, I discuss multifunctional channels named “adhennels” based on structures analyzed using electron and X-ray crystallography. PMID:26560835

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

PubMed

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

2013-02-01

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

Nucleotide-Specific Contrast for DNA Sequencing by Electron Spectroscopy.

PubMed

Mankos, Marian; Persson, Henrik H J; N'Diaye, Alpha T; Shadman, Khashayar; Schmid, Andreas K; Davis, Ronald W

2016-01-01

DNA sequencing by imaging in an electron microscope is an approach that holds promise to deliver long reads with low error rates and without the need for amplification. Earlier work using transmission electron microscopes, which use high electron energies on the order of 100 keV, has shown that low contrast and radiation damage necessitates the use of heavy atom labeling of individual nucleotides, which increases the read error rates. Other prior work using scattering electrons with much lower energy has shown to suppress beam damage on DNA. Here we explore possibilities to increase contrast by employing two methods, X-ray photoelectron and Auger electron spectroscopy. Using bulk DNA samples with monomers of each base, both methods are shown to provide contrast mechanisms that can distinguish individual nucleotides without labels. Both spectroscopic techniques can be readily implemented in a low energy electron microscope, which may enable label-free DNA sequencing by direct imaging.

Faunal composition and organic surface encrustations at hydrothermal vents on the southern Juan De Fuca Ridge

NASA Astrophysics Data System (ADS)

Tunnicliffe, Verena; Fontaine, A. R.

1987-10-01

Examination of a small collection of macroinvertebrates from three vents of the southern Juan de Fuca vent field reveals differences between the vents with respect to species composition, species habits, and microbial and metallic deposits on their surfaces. TWo apparently new vestimentiferan species were found, and for the first time the Juan de Fuca palm worm was observed to dwell on smokers. High acidity values recorded in this system may interfere with the process of shell calcification in an archaeogastropod snail. The surfaces of vestimentifer an tubes at two vents are heavily encrusted with microbial and metallic accumulations. Scanning electron microscope, transmission electron microscope, and energy dispersive X ray microanalysis observations show that iron-based crusts on orange tubes are built from accumulations of an Fe-rich particle of distinctive size and shape. Morphological evidence is presented for the microbial origin of Fe-rich particles. Zn-rich particles found on black tubes are not of microbial origin. We suggest that iron deposition on surfaces in the vent environment is initially biocatalytic but subsequent deposits may build by simple inorganic reactions.

Morphology and Viability of Pleistocene Microbiota from the CRREL Permafrost Tunnel Near Fox, Alaska

NASA Technical Reports Server (NTRS)

Hoover, Richard B.

2000-01-01

The U. S. Army Cold Regions Research and Engineering Laboratory maintains the CRREL Permafrost Tunnel at Fox, Alaska (-10 miles north of Fairbanks.) The active microbial ecosystems and the cryopreserved anabiotic viable microorganisms and dead microbial remains and biomarkers frozen within the permafrost and ice of the CRREL Permafrost Tunnel are of direct relevance to Astrobiology. Microbial extremophiles from permafrost and ice provide information concerning where and how should we search for evidence of life elsewhere in the Cosmos. The permafrost and ice wedges of the Fox tunnel preserves a magnificent of record of Pliocene, Pleistocene and Holocene life on Earth spanning more than 2.5 million years. This record includes frozen fossil bacteria, archaea, algae, mosses, higher plants, insects and mammals. In this paper we present the preliminary results of studies of the morphology, ultramicrostructure and elemental distributions of Fox tunnel microbiota as determined in-situ by the Environmental Scanning Electron Microscope (ESEM) and the Field Emission Scanning Electron Microscope (FESEM) investigations. The long-term viability of cryopreserved microbiota and potential implications to Astrobiology will be discussed.

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

PubMed

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

2014-08-01

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

Surface-plasmon-polariton hybridized cavity modes in submicrometer slits in a thin Au film

NASA Astrophysics Data System (ADS)

Walther, R.; Fritz, S.; Müller, E.; Schneider, R.; Maniv, T.; Cohen, H.; Matyssek, C.; Busch, K.; Gerthsen, D.

2016-06-01

The excitation of cavity standing waves in double-slit structures in thin gold films, with slit lengths between 400 and 2560 nm, was probed with a strongly focused electron beam in a transmission electron microscope. The energies and wavelengths of cavity modes up to the 11 th mode order were measured with electron energy loss spectroscopy to derive the corresponding dispersion relation. For all orders, a significant redshift of mode energies accompanied by a wavelength elongation relative to the expected resonator energies and wavelengths is observed. The resultant dispersion relation is found to closely follow the well-known dispersion law of surface-plasmon polaritons (SPPs) propagating on a gold/air interface, thus providing direct evidence for the hybridized nature of the detected cavity modes with SPPs.

Spontaneous breaking of time-reversal symmetry in strongly interacting two-dimensional electron layers in silicon and germanium.

PubMed

Shamim, S; Mahapatra, S; Scappucci, G; Klesse, W M; Simmons, M Y; Ghosh, A

2014-06-13

We report experimental evidence of a remarkable spontaneous time-reversal symmetry breaking in two-dimensional electron systems formed by atomically confined doping of phosphorus (P) atoms inside bulk crystalline silicon (Si) and germanium (Ge). Weak localization corrections to the conductivity and the universal conductance fluctuations were both found to decrease rapidly with decreasing doping in the Si:P and Ge:P delta layers, suggesting an effect driven by Coulomb interactions. In-plane magnetotransport measurements indicate the presence of intrinsic local spin fluctuations at low doping, providing a microscopic mechanism for spontaneous lifting of the time-reversal symmetry. Our experiments suggest the emergence of a new many-body quantum state when two-dimensional electrons are confined to narrow half-filled impurity bands.

High-resolution electron microscope

NASA Technical Reports Server (NTRS)

Nathan, R.

1977-01-01

Employing scanning transmission electron microscope as interferometer, relative phases of diffraction maximums can be determined by analysis of dark field images. Synthetic aperture technique and Fourier-transform computer processing of amplitude and phase information provide high resolution images at approximately one angstrom.

75 FR 9867 - University of Pittsburgh, et al

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-04

... DEPARTMENT OF COMMERCE International Trade Administration University of Pittsburgh, et al.; Notice of Consolidated Decision on Applications for Duty-Free Entry of Electron Microscopes This is a...: University of Pittsburgh, Pittsburgh, PA 15260. Instrument: Electron Microscope. Manufacturer: JEOL, Ltd...

Development of a miniature scanning electron microscope for in-flight analysis of comet dust

NASA Technical Reports Server (NTRS)

Conley, J. M.; Bradley, J. G.; Giffin, C. E.; Albee, A. L.; Tomassian, A. D.

1983-01-01

A description is presented of an instrument which was developed with the original goal of being flown on the International Comet Mission, scheduled for a 1985 launch. The Scanning Electron Microscope and Particle Analyzer (SEMPA) electron miniprobe is a miniaturized electrostatically focused electron microscope and energy dispersive X-ray analyzer for in-flight analysis of comet dust particles. It was designed to be flown on board a comet rendezvous spacecraft. Other potential applications are related to asteroid rendezvous and planetary lander missions. According to the development objectives, SEMPA miniprobe is to have the capability for imaging and elemental analysis of particles in the size range of 0.25 microns and larger.

Profiling with the electron microscope.

NASA Technical Reports Server (NTRS)

Vedder, J. F.; Lem, H. Y.

1972-01-01

Discussion of a profiling technique using a scanning electron microscope for obtaining depth information on a single micrograph of a small specimen. A stationary electron beam is used to form a series of contamination spots in a line across the specimen. Micrographs obtained by this technique are useful as a means of projection and display where stereo viewers are not practical.

Determination of atomic-scale chemical composition at semiconductor heteroepitaxial interfaces by high-resolution transmission electron microscopy.

PubMed

Wen, C; Ma, Y J

2018-03-01

The determination of atomic structures and further quantitative information such as chemical compositions at atomic scale for semiconductor defects or heteroepitaxial interfaces can provide direct evidence to understand their formation, modification, and/or effects on the properties of semiconductor films. The commonly used method, high-resolution transmission electron microscopy (HRTEM), suffers from difficulty in acquiring images that correctly show the crystal structure at atomic resolution, because of the limitation in microscope resolution or deviation from the Scherzer-defocus conditions. In this study, an image processing method, image deconvolution, was used to achieve atomic-resolution (∼1.0 Å) structure images of small lattice-mismatch (∼1.0%) AlN/6H-SiC (0001) and large lattice-mismatch (∼8.5%) AlSb/GaAs (001) heteroepitaxial interfaces using simulated HRTEM images of a conventional 300-kV field-emission-gun transmission electron microscope under non-Scherzer-defocus conditions. Then, atomic-scale chemical compositions at the interface were determined for the atomic intermixing and Lomer dislocation with an atomic step by analyzing the deconvoluted image contrast. Furthermore, the effect of dynamical scattering on contrast analysis was also evaluated for differently weighted atomic columns in the compositions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Classification of Streptomyces Spore Surfaces into Five Groups

PubMed Central

Dietz, Alma; Mathews, John

1971-01-01

Streptomyces spores surfaces have been classified into five groups, smooth, warty, spiny, hairy, and rugose, by examination of carbon replicas of spores with the transmission electron microscope and by direct examination of spores with the scanning electron microscope. Images PMID:4928607

COLONIAL GROWTH OF MYCOPLASMA GALLISEPTICUM OBSERVED WITH THE ELECTRON MICROSCOPE

PubMed Central

Shifrine, Moshe; Pangborn, Jack; Adler, Henry E.

1962-01-01

Shifrine, Moshe (University of California, Davis), Jack Pangborn, and Henry E. Adler. Colonial growth of Mycoplasma gallisepticum observed with the electron microscope. J. Bacteriol. 83:187–192. 1962.—Mycoplasma gallisepticum strain S6 was grown on collodion film on solid medium. Samples were removed every few hours, fixed, washed, shadowed, and observed with the electron microscope. Three distinct forms of growth were observed: elementary cells (hexagonally shaped), platycytes, and exoblasts. A tentative mode of growth was postulated. The significance of the angular morphology to the relation between mycoplasmas and L-forms of bacteria is discussed. Images PMID:13911868

In situ electronic probing of semiconducting nanowires in an electron microscope.

PubMed

Fauske, V T; Erlbeck, M B; Huh, J; Kim, D C; Munshi, A M; Dheeraj, D L; Weman, H; Fimland, B O; Van Helvoort, A T J

2016-05-01

For the development of electronic nanoscale structures, feedback on its electronic properties is crucial, but challenging. Here, we present a comparison of various in situ methods for electronically probing single, p-doped GaAs nanowires inside a scanning electron microscope. The methods used include (i) directly probing individual as-grown nanowires with a sharp nano-manipulator, (ii) contacting dispersed nanowires with two metal contacts and (iii) contacting dispersed nanowires with four metal contacts. For the last two cases, we compare the results obtained using conventional ex situ litho-graphy contacting techniques and by in situ, direct-write electron beam induced deposition of a metal (Pt). The comparison shows that 2-probe measurements gives consistent results also with contacts made by electron beam induced deposition, but that for 4-probe, stray deposition can be a problem for shorter nanowires. This comparative study demonstrates that the preferred in situ method depends on the required throughput and reliability. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

[Experimental study of restiffening of the rigor mortis].

PubMed

Wang, X; Li, M; Liao, Z G; Yi, X F; Peng, X M

2001-11-01

To observe changes of the length of sarcomere of rat when restiffening. We measured the length of sarcomere of quadriceps in 40 rats in different condition by scanning electron microscope. The length of sarcomere of rigor mortis without destroy is obviously shorter than that of restiffening. The length of sarcomere is negatively correlative to the intensity of rigor mortis. Measuring the length of sarcomere can determine the intensity of rigor mortis and provide evidence for estimation of time since death.

Studies of Brazilian meteorites. XIV - Mineralogy, petrology, and chemistry of the Conquista, Minas Gerais, chondrite

NASA Technical Reports Server (NTRS)

Keil, K.; Kirchner, E.; Gomes, C. B.; Jarosewich, E.; Murta, R. L. L.

1978-01-01

The Conquista chondrite is described and classified as an H4. The mineral composition is reported. H-group classification is based on described microscopic, electron microprobe, and bulk chemical studies. The evidence for petrologic type 4 classification includes the pronounced well-developed chondritic texture; the slight compositional variations in constituent phases; the high Ca contents of pyroxene and the presence of pigeonite; glassy to microcrystalline interstitial material rich in alkalis and SiO2; and twinned low-Ca clinopyroxene.

Quasiparticle pair creation in unstable superflow

NASA Astrophysics Data System (ADS)

Elser, Veit

1995-06-01

Landau's instability mechanism in superflow is considered with special attention given to the role of nonuniformity in the flow. Linear stability analysis applied to the first in a series of approximate microscopic equations for the superfluid reveals a growth rate for Landau's instability proportional to the shear in the flow. In a quasiparticle description, the shear acts as a source of particle pair creation. The observation of roton-pair creation in experiments with electron bubbles in helium is offered as evidence of this phenomenon.

In situ studies on radiation tolerance of nanotwinned Cu

DOE PAGES

Chen, Y.; Li, J.; Yu, K. Y.; ...

2016-03-31

We investigate the radiation response of nanotwinned Cu by using in situ Kr ion irradiation technique inside a transmission electron microscope. In comparison with coarse grained Cu, nanotwinned Cu exhibits smaller defect size and lower defect density. In situ studies also show that twin boundaries effectively remove a large number of defect clusters. The life time of defect clusters in nanotwinned Cu is very different from that in its coarse grained counterpart. This study provides further evidence on twin-boundary enabled radiation tolerance in nanotwinned metals.

In Situ Formation of Carbon Nanotubes Encapsulated within Boron Nitride Nanotubes via Electron Irradiation

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

Arenal, Raul; Lopez-Bezanilla, Alejandro

2014-07-25

We report experimental evidence of the formation by in situ electron-irradiation of single-walled carbon nanotubes (C NT) confined within boron nitride nanotubes (BN-NT). The electron radiation stemming from the microscope supplies the energy required by the amorphous carbonaceous structures to crystallize in a tubular form in a catalyst free procedure, at room temperature and high vacuum. The structural defects resulting from the interaction of the shapeless carbon with the BN nanotube are corrected in a self-healing process throughout the crystallinization. Structural changes developed during the irradiation process such as defects formation and evolution, shrinkage, and shortness of the BN-NT weremore » in situ monitored. The outer BN wall provides a protective and insulating shell against environmental Perturbations to the inner C-NT without affecting their electronic properties, as demonstrated by first principles calculations.« less

Transmission electron microscope studies of extraterrestrial materials

NASA Technical Reports Server (NTRS)

Keller, Lindsay P.

1995-01-01

Transmission Electron Microscopy, X-Ray spectrometry and electron-energy-loss spectroscopy are used to analyse carbon in interplanetary dust particles. Optical micrographs are shown depicting cross sections of the dust particles embedded in sulphur. Selected-area electron diffraction patterns are shown. Transmission Electron Microscope specimens of lunar soil were prepared using two methods: ion-milling and ultramicrotomy. A combination of high resolution TEM imaging and electron diffraction is used to characterize the opaque assemblages. The opaque assemblages analyzed in this study are dominated by ilmenite with lesser rutile and spinel exsolutions, and traces of Fe metal.

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

Zhou, T.Q.; Buczkowski, A.; Radzimski, Z.J.

The electrical activity of as-grown and intentionally decorated misfit dislocations in an epitaxial Si/Si(Ge) heterostructure was examined using the electron beam induced current (EBIC) technique in a scanning electron microscope. Misfit dislocations, which were not visible initially, were subsequently activated either by an unknown processing contaminant or a backside metallic impurity. Passivation of these contaminated dislocations was then studied using low energy deuterium ion implantation in a Kaufman ion source. EBIC results show that the recombination activity of the decorated misfit dislocations was dramatically reduced by the deuterium treatment. Although a front side passivation treatment was more effective than amore » backside treatment, a surface ion bombardment damage problem is still evident. 5 refs., 3 figs.« less

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

DTIC Science & Technology

2017-06-29

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

Damage-free vibrational spectroscopy of biological materials in the electron microscope

PubMed Central

Rez, Peter; Aoki, Toshihiro; March, Katia; Gur, Dvir; Krivanek, Ondrej L.; Dellby, Niklas; Lovejoy, Tracy C.; Wolf, Sharon G.; Cohen, Hagai

2016-01-01

Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an ‘aloof' electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies <1 eV can be ‘safely' investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C–H, N–H and C=O vibrational signatures with no observable radiation damage. The technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ∼10 nm, simultaneously combined with imaging in the electron microscope. PMID:26961578

Damage-free vibrational spectroscopy of biological materials in the electron microscope.

PubMed

Rez, Peter; Aoki, Toshihiro; March, Katia; Gur, Dvir; Krivanek, Ondrej L; Dellby, Niklas; Lovejoy, Tracy C; Wolf, Sharon G; Cohen, Hagai

2016-03-10

Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an 'aloof' electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies <1 eV can be 'safely' investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C-H, N-H and C=O vibrational signatures with no observable radiation damage. The technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ∼10 nm, simultaneously combined with imaging in the electron microscope.

Damage-free vibrational spectroscopy of biological materials in the electron microscope

DOE PAGES

Rez, Peter; Aoki, Toshihiro; March, Katia; ...

2016-03-10

Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an ‘aloof’ electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies o1 eV can be ‘safely’ investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C–H, N–H and C=O vibrational signatures with nomore » observable radiation damage. Furthermore, the technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ~10nm, simultaneously combined with imaging in the electron microscope.« less

Damage-free vibrational spectroscopy of biological materials in the electron microscope

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

Rez, Peter; Aoki, Toshihiro; March, Katia

Vibrational spectroscopy in the electron microscope would be transformative in the study of biological samples, provided that radiation damage could be prevented. However, electron beams typically create high-energy excitations that severely accelerate sample degradation. Here this major difficulty is overcome using an ‘aloof’ electron beam, positioned tens of nanometres away from the sample: high-energy excitations are suppressed, while vibrational modes of energies o1 eV can be ‘safely’ investigated. To demonstrate the potential of aloof spectroscopy, we record electron energy loss spectra from biogenic guanine crystals in their native state, resolving their characteristic C–H, N–H and C=O vibrational signatures with nomore » observable radiation damage. Furthermore, the technique opens up the possibility of non-damaging compositional analyses of organic functional groups, including non-crystalline biological materials, at a spatial resolution of ~10nm, simultaneously combined with imaging in the electron microscope.« less

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

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

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

2016-10-01

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

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

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

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

2016-03-30

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

A Student-Built Scanning Tunneling Microscope

ERIC Educational Resources Information Center

Ekkens, Tom

2015-01-01

Many introductory and nanotechnology textbooks discuss the operation of various microscopes including atomic force (AFM), scanning tunneling (STM), and scanning electron microscopes (SEM). In a nanotechnology laboratory class, students frequently utilize microscopes to obtain data without a thought about the detailed operation of the tool itself.…

78 FR 2659 - Application(s) for Duty-Free Entry of Scientific Instruments

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-14

..., 2201 West End Ave., Nashville, TN 37235. Instrument: Electron Microscope. Manufacturer: FEI Company... St., West Lafayette, IN 47907-2024. Instrument: Electron Microscope. Manufacturer: FEI Company, the..., microorganisms, nanomaterials, and chemical compounds. Justification for Duty-Free Entry: There are no...

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

PubMed Central

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

2005-01-01

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

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

PubMed

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

2005-06-21

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

Microscopic origin of the fast blue-green luminescence of chemically synthesized non-oxidized silicon quantum dots.

PubMed

Dohnalová, Kateřina; Fučíková, Anna; Umesh, Chinnaswamy P; Humpolíčková, Jana; Paulusse, Jos M J; Valenta, Jan; Zuilhof, Han; Hof, Martin; Gregorkiewicz, Tom

2012-10-22

The microscopic origin of the bright nanosecond blue-green photoluminescence (PL), frequently reported for synthesized organically terminated Si quantum dots (Si-QDs), has not been fully resolved, hampering potential applications of this interesting material. Here a comprehensive study of the PL from alkyl-terminated Si-QDs of 2-3 nm size, prepared by wet chemical synthesis is reported. Results obtained on the ensemble and those from the single nano-object level are compared, and they provide conclusive evidence that efficient and tunable emission arises due to radiative recombination of electron-hole pairs confined in the Si-QDs. This understanding paves the way towards applications of chemical synthesis for the development of Si-QDs with tunable sizes and bandgaps. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microcellular nanocomposite injection molding process

Treesearch

Mingjun Yuan; Lih-Sheng Turng; Rick Spindler; Daniel Caulfield; Chris Hunt

2003-01-01

This study aims to explore the processing benefits and property improvements of combining nanocomposites with microcellular injection molding. The molded parts produced based on the Design of Experiments (DOE) matrices were subjected to tensile testing, impact testing, and Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Dynamic Mechanical...

The microscopic world: A demonstration of electron microscopy for younger students

NASA Technical Reports Server (NTRS)

Horton, Linda L.

1992-01-01

The purpose is to excite students about the importance of scientific investigation and demonstrate why they should look at things in greater detail, extending beyond superficial examination. The topics covered include: microscopy, scanning electron microscopes, high magnification, and the scientific method.

Electron density distribution in BaPb{sub 1-x}Sb{sub x}O{sub 3} superconducting oxides studied by double nuclear magnetic resonance methods

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

Piskunov, Yu. V., E-mail: piskunov@imp.uran.ru; Ogloblichev, V. V.; Arapova, I. Yu.

2011-11-15

The effect of charge disorder on the formation of an inhomogeneous state of the electron system in the conduction band in BaPb{sub 1-x}Sb{sub x}O{sub 3} superconducting oxides is investigated experimentally by NMR methods. The NMR spectra of {sup 17}O are measured systematically, and the contributions from {sup 17}O atoms with different cation nearest surroundings are identified. It is found that microscopic regions with an elevated spin density of charge carriers are formed within two coordination spheres near antimony ions. Nuclei of the superconducting phase of the oxide (regions with an elevated antimony concentration) microscopically distributed over the sample are detectedmore » in compounds with x = 0.25 and 0.33. Experiments in which a double resonance signal of the spin echo of {sup 17}O-{sup 207}Pb and {sup 17}O-{sup 121}Sb are measured in the metal phase of BaPb{sub 1-x}Sb{sub x}O{sub 3} oxides are carried out for the first time. The constants of indirect heteronuclear spin-spin {sup 17}O-{sup 207}Pb interaction are determined as functions of the local Knight shift {sub 207}Ks. The estimates of the constants of the indirect interaction between the nuclei of the nearest neighbors (O-Pb and Pb-Pb atoms) and analysis of evolution of the NMR spectra of {sup 17}O upon a change in the antimony concentration are convincing evidence in favor of the development of a microscopically inhomogeneous state of the electron system in the metal phase of BaPb{sub 1-x}Sb{sub x}O{sub 3} oxides.« less

Nucleotide-Specific Contrast for DNA Sequencing by Electron Spectroscopy

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

Mankos, Marian; Persson, Henrik H. J.; N’Diaye, Alpha T.

DNA sequencing by imaging in an electron microscope is an approach that holds promise to deliver long reads with low error rates and without the need for amplification. Earlier work using transmission electron microscopes, which use high electron energies on the order of 100 keV, has shown that low contrast and radiation damage necessitates the use of heavy atom labeling of individual nucleotides, which increases the read error rates. Other prior work using scattering electrons with much lower energy has shown to suppress beam damage on DNA. Here we explore possibilities to increase contrast by employing two methods, X-ray photoelectronmore » and Auger electron spectroscopy. Using bulk DNA samples with monomers of each base, both methods are shown to provide contrast mechanisms that can distinguish individual nucleotides without labels. In conclusion, both spectroscopic techniques can be readily implemented in a low energy electron microscope, which may enable label-free DNA sequencing by direct imaging.« less

Nucleotide-Specific Contrast for DNA Sequencing by Electron Spectroscopy

DOE PAGES

Mankos, Marian; Persson, Henrik H. J.; N’Diaye, Alpha T.; ...

2016-05-05

DNA sequencing by imaging in an electron microscope is an approach that holds promise to deliver long reads with low error rates and without the need for amplification. Earlier work using transmission electron microscopes, which use high electron energies on the order of 100 keV, has shown that low contrast and radiation damage necessitates the use of heavy atom labeling of individual nucleotides, which increases the read error rates. Other prior work using scattering electrons with much lower energy has shown to suppress beam damage on DNA. Here we explore possibilities to increase contrast by employing two methods, X-ray photoelectronmore » and Auger electron spectroscopy. Using bulk DNA samples with monomers of each base, both methods are shown to provide contrast mechanisms that can distinguish individual nucleotides without labels. In conclusion, both spectroscopic techniques can be readily implemented in a low energy electron microscope, which may enable label-free DNA sequencing by direct imaging.« less

A next generation positron microscope and a survey of candidate samples for future positron studies

NASA Astrophysics Data System (ADS)

Dull, Terry Lou

A positron microscope has been constructed and is nearing the conclusion of its assembly and testing. The instrument is designed to perform positron and electron microscopy in both scanning and magnifying modes. In scanning mode, a small beam of particles is rastered across the target and the amplitude of a positron or electron related signal is recorded as a function of position. For positrons this signal may come from Doppler Broadening Spectroscopy, Reemitted Positron Spectroscopy or Positron Annihilation Lifetime Spectroscopy. For electrons this signal may come from the number of secondary electrons or Auger Electron Spectroscopy. In magnifying mode an incident beam of particles is directed onto the target and emitted particles, either secondary electrons or reemitted positrons, are magnified to form an image. As a positron microscope the instrument will primarily operate in magnifying mode, as a positron reemission microscope. As an electron microscope the instrument will be able to operate in both magnifying and scanning modes. Depth-profiled Doppler Broadening Spectroscopy studies using a non-microscopic low-energy positron beam have also been performed on a series of samples to ascertain the applicability of positron spectroscopies and/or microscopy to their study. All samples have sub-micron film and/or feature size and thus are only susceptible to positron study with low-energy beams. Several stoichiometries and crystallinities of chalcogenide thin films (which can be optically reversibly switched between crystalline states) were studied and a correlation was found to exist between the amorphous/FCC S-parameter difference and the amorphous/FCC switching time. Amorphous silicon films were studied in an attempt to observe the well-established Staebler-Wronski effect as well as the more controversial photodilatation effect. However, DBS was not able to detect either effect. The passive oxide films on titanium and aluminum were studied in an attempt to verify the Point Defect Model, a detailed, but as yet microscopically unconfirmed, theory of the corrosive breakdown of passive films. DBS results supportive of the PDM were observed. Graphitic carbon fibers were also studied and DBS indicated the presence of a 200 nm thick outer fiber skin possibly characterized by a high degree of graphitic crystallite alignment.

Microscopic Electron Variations Measured Simultaneously By The Cluster Spacecraft

NASA Astrophysics Data System (ADS)

Buckley, A. M.; Carozzi, T. D.; Gough, M. P.; Beloff, N.

Data is used from the Particle Correlator experiments running on each of the four Cluster spacecraft so as to determine common microscopic behaviour in the elec- tron population observed over the macroscopic Cluster separations. The Cluster par- ticle correlator experiments operate by forming on board Auto Correlation Functions (ACFs) generated from short time series of electron counts obtained, as a function of electron energy, from the PEACE HEEA sensor. The information on the microscopic variation of the electron flux covers the frequency range DC up to 41 kHz (encom- passing typical electron plasma frequencies and electron gyro frequencies and their harmonics), the electron energy range is that covered by the PEACE HEEA sensor (within the range 1 eV to 26 keV). Results are presented of coherent electron struc- tures observed simultaneously by the four spacecraft in the differing plasma interac- tion regions and boundaries encountered by Cluster. As an aid to understanding the plasma interactions, use is made of numerical simulations which model both the un- derlying statistical properties of the electrons and also the manner in which particle correlator experiments operate.

Interference experiment with asymmetric double slit by using 1.2-MV field emission transmission electron microscope.

PubMed

Harada, Ken; Akashi, Tetsuya; Niitsu, Kodai; Shimada, Keiko; Ono, Yoshimasa A; Shindo, Daisuke; Shinada, Hiroyuki; Mori, Shigeo

2018-01-17

Advanced electron microscopy technologies have made it possible to perform precise double-slit interference experiments. We used a 1.2-MV field emission electron microscope providing coherent electron waves and a direct detection camera system enabling single-electron detections at a sub-second exposure time. We developed a method to perform the interference experiment by using an asymmetric double-slit fabricated by a focused ion beam instrument and by operating the microscope under a "pre-Fraunhofer" condition, different from the Fraunhofer condition of conventional double-slit experiments. Here, pre-Fraunhofer condition means that each single-slit observation was performed under the Fraunhofer condition, while the double-slit observations were performed under the Fresnel condition. The interference experiments with each single slit and with the asymmetric double slit were carried out under two different electron dose conditions: high-dose for calculation of electron probability distribution and low-dose for each single electron distribution. Finally, we exemplified the distribution of single electrons by color-coding according to the above three types of experiments as a composite image.

Pre-microscope tunnelling — Inspiration or constraint?

NASA Astrophysics Data System (ADS)

Walmsley, D. G.

1987-03-01

Before the microscope burst upon the scene, tunnelling had established for itself a substantial niche in the repertoire of the solid state physicist. Over a period of 20 years it has contributed importantly to our understanding of many systems. It elucidated the superconducting state, first by a direct display of the energy gap then by providing detailed information on the phonon spectra and electron-phonon coupling strength in junction electrodes. Its use as a phonon spectrometer was subsequently extended to semiconductors and to the oxides of insulating barriers. Eventually the vibrational spectra of monolayer organic and inorganic adsorbates became amenable with rich scientific rewards. In a few cases electronic transitions have been observed. Plasmon excitation by tunnelling electrons led to insights on the electron loss function in metals at visible frequencies and provided along the way an intriguing light emitting device. With the advent of the microscope it is now appropriate to enquire how much of this experience can profitably be carried over to the new environment. Are we constrained just to repeat the experiments in a new configuration? Happily no. The microscope offers us topographical and spectroscopic information of a new order. One might next ask how great is the contact between the two disciplines? We explore this question and seek to establish where the pre-microscope experience can be helpful in inspiring our use of this marvellous new facility that we know as the scanning tunnelling microscope.

Electronic structure and microscopic model of V(2)GeO(4)F(2)-a quantum spin system with S = 1.

PubMed

Rahaman, Badiur; Saha-Dasgupta, T

2007-07-25

We present first-principles density functional calculations and downfolding studies of the electronic and magnetic properties of the oxide-fluoride quantum spin system V(2)GeO(4)F(2). We discuss explicitly the nature of the exchange paths and provide quantitative estimates of magnetic exchange couplings. A microscopic modelling based on analysis of the electronic structure of this systems puts it in the interesting class of weakly coupled alternating chain S = 1 systems. Based on the microscopic model, we make inferrences about its spin excitation spectra, which needs to be tested by rigorous experimental study.

Miniature self-contained vacuum compatible electronic imaging microscope

DOEpatents

Naulleau, Patrick P.; Batson, Phillip J.; Denham, Paul E.; Jones, Michael S.

2001-01-01

A vacuum compatible CCD-based microscopic camera with an integrated illuminator. The camera can provide video or still feed from the microscope contained within a vacuum chamber. Activation of an optional integral illuminator can provide light to illuminate the microscope subject. The microscope camera comprises a housing with a objective port, modified objective, beam-splitter, CCD camera, and LED illuminator.

Electron Source Brightness and Illumination Semi-Angle Distribution Measurement in a Transmission Electron Microscope.

PubMed

Börrnert, Felix; Renner, Julian; Kaiser, Ute

2018-05-21

The electron source brightness is an important parameter in an electron microscope. Reliable and easy brightness measurement routes are not easily found. A determination method for the illumination semi-angle distribution in transmission electron microscopy is even less well documented. Herein, we report a simple measurement route for both entities and demonstrate it on a state-of-the-art instrument. The reduced axial brightness of the FEI X-FEG with a monochromator was determined to be larger than 108 A/(m2 sr V).

An ultrafast electron microscope gun driven by two-photon photoemission from a nanotip cathode

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

Bormann, Reiner; Strauch, Stefanie; Schäfer, Sascha, E-mail: schaefer@ph4.physik.uni-goettingen.de

We experimentally and numerically investigate the performance of an advanced ultrafast electron source, based on two-photon photoemission from a tungsten needle cathode incorporated in an electron microscope gun geometry. Emission properties are characterized as a function of the electrostatic gun settings, and operating conditions leading to laser-triggered electron beams of very low emittance (below 20 nm mrad) are identified. The results highlight the excellent suitability of optically driven nano-cathodes for the further development of ultrafast transmission electron microscopy.

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

NASA Technical Reports Server (NTRS)

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

1989-01-01

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

A new heterolobosean amoeba Solumitrus palustris n. g., n. sp. isolated from freshwater marsh soil.

PubMed

Anderson, O Roger; Wang, Wen; Faucher, Sebastien P; Bi, Keran; Shuman, Howard A

2011-01-01

During the course of research on the bacterial feeding behavior and resistance of amoebae to virulent pathogens, we isolated a new strain of amoeba from organic rich soil at the margin of freshwater swamp in the northeastern United States. Light microscopic morphology is characteristically heterolobosean, resembling vahlkampfiids, including a broadened, limax shape, and eruptive locomotion, but occasionally becoming more contracted and less elongated with lateral or anterior bulges and somewhat branching sparse, uroidal filaments. Electron microscopic evidence, including mitochondria with flattened cristae surrounded by rough endoplasmic reticulum, further indicates a heterolobosean affinity. The solitary nucleus contains a centrally located nucleolus. Cysts are rounded with occasionally an eccentrically located nucleus. The cyst walls are relatively thin, becoming crenated, and loosely enclosing the cyst when mature. Molecular genetic evidence places this isolate among the Heterolobosea, branching most closely in a clade including Allovahlkampfia spelaea and previously isolated, un-named strains of soil amoebae. Based on differentiated features, including morphology of the uroid, cyst wall structure, and molecular genetic evidence that distinguish it from A. spelaea, a new genus and species, Solumitrus palustris, is proposed for this new heterolobosean. © 2010 The Author(s). Journal of Eukaryotic Microbiology © 2010 International Society of Protistologists.

Mechanisms of high-gradient microwave breakdown on metal surfaces in high power microwave source

NASA Astrophysics Data System (ADS)

Xie, Jialing; Chen, Changhua; Chang, Chao; Wu, Cheng; Huo, Yankun

2017-12-01

A breakdown cavity was designed to study the high-gradient microwave breakdown on a metal surface. The breakdown cavity can be distinguished into an electron emission boundary and a bombardment boundary as there is an evident difference in amplitude of the electric field between the two planes in the cavity. Breakdown tracks on the cavity were studied with an electron scanning microscope. The tracks on the electron emission boundary with the higher electric field were eroded; a component analysis indicates that these tracks contain an emission boundary material. On the bombardment boundary with a lower electric field, two kinds of tracks exist: an erosion track containing a bombardment boundary material and a sputtered track containing an emission boundary material. From these tracks, the mechanisms of high-gradient microwave breakdown on a metal surface have been analyzed.

SPE-LEEM Studies on the Surface and Electronic Structure of 2-D Transition Metal Dichalcogenides

NASA Astrophysics Data System (ADS)

Yeh, Po-Chun; Jin, Wencan; Zaki, Nader; Zhang, Datong; Sadowski, Jerzy; Al-Mahboob, Abdullah; van de Zande, Arend; Chenet, Daniel; Dadap, Jerry; Herman, Irving; Sutter, Petter; Hone, James; Osgood, Richard

2014-03-01

In this work, we studied the surface and electronic structure of monolayer and few-layer exfoliated MoS2 and WSe2, as well as chemical-vapor-deposition (CVD) grown MoS2, using Spectroscopic Photoemission and Low Energy Electron Microscope (SPE-LEEM). LEEM measurements reveal that, unlike exfoliated MoS2, CVD-grown MoS2 exhibits grain-boundary alterations due to surface strain. However, LEEM and micro-probe low energy electron diffraction show that the quality of CVD-grown MoS2 is comparable to that of exfoliated MoS2. Micrometer-scale angle-resolved photoemission spectroscopy (ARPES) measurement on exfoliated MoS2 and WSe2 single-crystals provides direct evidence for the shifting of the valence band maximum from Γ to K, when the layer number is thinned down to one, as predicted by density functional theory. Our measurements of the k-space resolved electronic structure allow for further comparison with other theoretical predictions and with transport measurements. Session I and II

Electron beam assisted field evaporation of insulating nanowires/tubes

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

Blanchard, N. P., E-mail: nicholas.blanchard@univ-lyon1.fr; Niguès, A.; Choueib, M.

2015-05-11

We demonstrate field evaporation of insulating materials, specifically BN nanotubes and undoped Si nanowires, assisted by a convergent electron beam. Electron irradiation leads to positive charging at the nano-object's apex and to an important increase of the local electric field thus inducing field evaporation. Experiments performed both in a transmission electron microscope and in a scanning electron microscope are presented. This technique permits the selective evaporation of individual nanowires in complex materials. Electron assisted field evaporation could be an interesting alternative or complementary to laser induced field desorption used in atom probe tomography of insulating materials.

The contributions of Otto Scherzer (1909-1982) to the development of the electron microscope.

PubMed

Marko, Michael; Rose, Harald

2010-08-01

Otto Scherzer was one of the pioneers of theoretical electron optics. He was coauthor of the first comprehensive book on electron optics and was the first to understand that round electron lenses could not be combined to correct aberrations, as is the case in light optics. He subsequently was the first to describe several alternative means to correct spherical and chromatic aberration of electron lenses. These ideas were put into practice by his laboratory and students at Darmstadt and their successors, leading to the fully corrected electron microscopes now in operation.

Evidence for Microfossils in Ancient Rocks and Meteorites

NASA Technical Reports Server (NTRS)

Hoover, Richard B.; Rozanov, A. Y.; Zhmur, S. I.; Gorlenko, V. M.

1998-01-01

The McKay et all. detection of chemical biomarkers and possible microfossils in an ancient meteorite from Mars (ALH84001) stimulated research in several areas of importance to the newly emerging field of Astrobiology. Their report resulted in a search for additional evidence of microfossils in ancient terrestrial rocks and meteorites. These studies of ancient rocks and meteorites were conducted independently (and later collaboratively) in the United States and Russia using the SEM, Environmental Scanning Electron Microscope (ESEM), and Field Emission Scanning Electron Microscope (FESEM). We have encountered in-situ in freshly broken carbonaceous chondrites a large number of complex microstructures that appear to be lithified microbial forms. The meteoritic microstructures have characteristics similar to the lithified remains of filamentous cyanobacteria and bacterial microfossils we have found in ancient phosphorites, ancient graphites and oil shales. Energy Dispersive Spectroscopy (EDS) and Link microprobe analysis shows the possible microfossils have a distribution of chemical elements characteristic of the meteorite rock matrix, although many exhibit a superimposed carbon enhancement. We have concluded that the mineralized bodies encountered embedded in the rock matrix of freshly fractured meteoritic surfaces can not be dismissed as recent surface contaminants. Many of the forms found in-situ in the Murchison, Efremovka, and Orgueil carbonaceous meteorites are strikingly similar to microfossils of coccoid bacteria, cyanobacteria and fungi such as we have found in the Cambrian phosphorites of Khubsugul, Mongolia and high carbon Phanerozoic and Precambrian rocks of the Siberian and Russian Platforms.

Application of automatic image analysis for morphometric studies of peroxisomes stained cytochemically for catalase. II. Light-microscopic application.

PubMed

Beier, K; Fahimi, H D

1987-01-01

The feasibility of the application of a television-based image analyzer, the Texture Analysis System (TAS, Leitz Wetzlar, FRG) in conjunction with a light microscope for morphometric studies of hepatic peroxisomes has been investigated. Rat liver peroxisomes were stained with the alkaline-DAB method for localization of catalase and semithin (0.25 and 1 micron) sections of plastic-embedded material were examined under an oil immersion objective. The TAS detected the peroxisomal profiles selectively and determined their morphometric parameters automatically. The same parameters were obtained also by morphometric analysis of electron micrographs from the same material. The volume density of peroxisomes determined by TAS in semithin sections of normal liver, after correction for section thickness, is quite close to the corresponding value obtained by morphometry of electron micrographs. The difference is approximately 20%. In animals treated with the hypolipidemic drug bezafibrate, which causes proliferation of peroxisomes, TAS detected readily the increase in volume density of peroxisomes in semithin sections. In comparison with electron microscopy, however, the light-microscopic approach seems to underestimate the proliferation. The lower resolution of the light microscope and overlapping of neighbouring particles in relatively thick sections used for light-microscopic analysis may account for the differences. The present study has demonstrated the usefulness of automatic image analysis in conjunction with selective cytochemical staining of peroxisomes for morphometry of this organelle in rat liver. The light-microscopic approach is not only faster but is also extremely economical by obviating the use of an electron microscope.

Electron beam induced deposition of silicon nanostructures from a liquid phase precursor.

PubMed

Liu, Yin; Chen, Xin; Noh, Kyong Wook; Dillon, Shen J

2012-09-28

This work demonstrates electron beam induced deposition of silicon from a SiCl(4) liquid precursor in a transmission electron microscope and a scanning electron microscope. Silicon nanodots of tunable size are reproducibly grown in controlled geometries. The volume of these features increases linearly with deposition time. The results indicate that secondary electrons generated at the substrate surface serve as the primary source of silicon reduction. However, at high current densities the influence of the primary electrons is observed to retard growth. The results demonstrate a new approach to fabricating silicon nanostructures and provide fundamental insights into the mechanism for liquid phase electron beam induced deposition.

Electron beam induced deposition of silicon nanostructures from a liquid phase precursor

NASA Astrophysics Data System (ADS)

Liu, Yin; Chen, Xin; Noh, Kyong Wook; Dillon, Shen J.

2012-09-01

This work demonstrates electron beam induced deposition of silicon from a SiCl4 liquid precursor in a transmission electron microscope and a scanning electron microscope. Silicon nanodots of tunable size are reproducibly grown in controlled geometries. The volume of these features increases linearly with deposition time. The results indicate that secondary electrons generated at the substrate surface serve as the primary source of silicon reduction. However, at high current densities the influence of the primary electrons is observed to retard growth. The results demonstrate a new approach to fabricating silicon nanostructures and provide fundamental insights into the mechanism for liquid phase electron beam induced deposition.

Transmission Electron Microscope Measures Lattice Parameters

NASA Technical Reports Server (NTRS)

Pike, William T.

1996-01-01

Convergent-beam microdiffraction (CBM) in thermionic-emission transmission electron microscope (TEM) is technique for measuring lattice parameters of nanometer-sized specimens of crystalline materials. Lattice parameters determined by use of CBM accurate to within few parts in thousand. Technique developed especially for use in quantifying lattice parameters, and thus strains, in epitaxial mismatched-crystal-lattice multilayer structures in multiple-quantum-well and other advanced semiconductor electronic devices. Ability to determine strains in indivdual layers contributes to understanding of novel electronic behaviors of devices.

Ponderomotive phase plate for transmission electron microscopes

DOEpatents

Reed, Bryan W [Livermore, CA

2012-07-10

A ponderomotive phase plate system and method for controllably producing highly tunable phase contrast transfer functions in a transmission electron microscope (TEM) for high resolution and biological phase contrast imaging. The system and method includes a laser source and a beam transport system to produce a focused laser crossover as a phase plate, so that a ponderomotive potential of the focused laser crossover produces a scattering-angle-dependent phase shift in the electrons of the post-sample electron beam corresponding to a desired phase contrast transfer function.

In situ flat embedding of monolayers and cell relocation in the acrylic resin LR white for comparative light and electron microscopy studies.

PubMed

Steiner, M; Schöfer, C; Mosgoeller, W

1994-12-01

A simple and reliable method has been developed for the in situ LR White embedding of cell monolayers grown on glass cover-slips. Combined with cytochemical or immunological procedures, this technique allows light and/or electron microscopy investigations of a large number of cells in the same horizontal plane within a relatively short period of time. It can be applied to cells grown on microgrid finder cover-slips which allows a distinct site of even an individual cell of a monolayer to be studied at first at the light microscope level and subsequently at the electron microscope level. Hence, it is also suitable for controlling manipulation of single cells, followed by their serial sectioning after relocation in the electron microscope.

Mars Life? - Microscopic Tubular Structures

NASA Image and Video Library

1996-08-09

This electron microscope image shows extremely tiny tubular structures that are possible microscopic fossils of bacteria-like organisms that may have lived on Mars more than 3.6 billion years ago. http://photojournal.jpl.nasa.gov/catalog/PIA00285

Mars Life? - Microscopic Egg-shaped Structures

NASA Image and Video Library

1996-08-09

This electron microscope image shows egg-shaped structures, some of which may be possible microscopic fossils of Martian origin as discussed by NASA research published in the Aug. 16, 1996. http://photojournal.jpl.nasa.gov/catalog/PIA00286

CHARACTERISTICS OF INDIVIDUAL PARTICLES AT A RURAL SITE IN THE EASTERN UNITED STATES

EPA Science Inventory

To determine the nature of aerosol particles in a rural area of the eastern United States, aerosol samples were collected at Deep Creek Lake, Maryland, on various substrates and analyzed by a scanning electron microscope (SEM) and a transmission electron microscope (TEM). SEM ana...

Characterization of calcium crystals in Abelia using x-ray diffraction and electron microscopes

USDA-ARS?s Scientific Manuscript database

Localization, chemical composition, and morphology of calcium crystals in leaves and stems of Abelia mosanensis and A. ×grandiflora were analyzed with a variable pressure scanning electron microscope (VP-SEM) equipped with an X-ray diffraction system, low temperature SEM (LT-SEM) and a transmission ...

77 FR 33422 - The Regents of the University of California, et al.; Notice of Consolidated Decision on...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-06

... DEPARTMENT OF COMMERCE International Trade Administration The Regents of the University of...: Washington University in St. Louis, Saint Louis, MO 63130. Instrument: Electron Microscope. Manufacturer: FEI.... Applicant: The Regents of the University of California, Berkeley, CA 94720. Instrument: Electron Microscope...

Neuroanatomy from Mesoscopic to Nanoscopic Scales: An Improved Method for the Observation of Semithin Sections by High-Resolution Scanning Electron Microscopy

PubMed Central

Rodríguez, José-Rodrigo; Turégano-López, Marta; DeFelipe, Javier; Merchán-Pérez, Angel

2018-01-01

Semithin sections are commonly used to examine large areas of tissue with an optical microscope, in order to locate and trim the regions that will later be studied with the electron microscope. Ideally, the observation of semithin sections would be from mesoscopic to nanoscopic scales directly, instead of using light microscopy and then electron microscopy (EM). Here we propose a method that makes it possible to obtain high-resolution scanning EM images of large areas of the brain in the millimeter to nanometer range. Since our method is compatible with light microscopy, it is also feasible to generate hybrid light and electron microscopic maps. Additionally, the same tissue blocks that have been used to obtain semithin sections can later be used, if necessary, for transmission EM, or for focused ion beam milling and scanning electron microscopy (FIB-SEM). PMID:29568263

Neuroanatomy from Mesoscopic to Nanoscopic Scales: An Improved Method for the Observation of Semithin Sections by High-Resolution Scanning Electron Microscopy.

PubMed

Rodríguez, José-Rodrigo; Turégano-López, Marta; DeFelipe, Javier; Merchán-Pérez, Angel

2018-01-01

Semithin sections are commonly used to examine large areas of tissue with an optical microscope, in order to locate and trim the regions that will later be studied with the electron microscope. Ideally, the observation of semithin sections would be from mesoscopic to nanoscopic scales directly, instead of using light microscopy and then electron microscopy (EM). Here we propose a method that makes it possible to obtain high-resolution scanning EM images of large areas of the brain in the millimeter to nanometer range. Since our method is compatible with light microscopy, it is also feasible to generate hybrid light and electron microscopic maps. Additionally, the same tissue blocks that have been used to obtain semithin sections can later be used, if necessary, for transmission EM, or for focused ion beam milling and scanning electron microscopy (FIB-SEM).

Variations in contrast of scanning electron microscope images for microstructure analysis of Si-based semiconductor materials.

PubMed

Itakura, Masaru; Kuwano, Noriyuki; Sato, Kaoru; Tachibana, Shigeaki

2010-08-01

Image contrasts of Si-based semiconducting materials have been investigated by using the latest scanning electron microscope with various detectors under a range of experimental conditions. Under a very low accelerating voltage (500 V), we obtained a good image contrast between crystalline SiGe whiskers and the amorphous matrix using an in-lens secondary electron (SE) detector, while the conventional topographic SE image and the compositional backscattered electron (BSE) image gave no distinct contrast. By using an angular-selective BSE (AsB) detector for wide-angle scattered BSE, on the other hand, the crystal grains in amorphous matrix can be clearly visualized as 'channelling contrast'. The image contrast is very similar to that of their transmission electron microscope image. The in-lens SE (true SE falling dots SE1) and the AsB (channelling) contrasts are quite useful to distinguish crystalline parts from amorphous ones.

Dynamic imaging with electron microscopy

ScienceCinema

Campbell, Geoffrey; McKeown, Joe; Santala, Melissa

2018-02-13

Livermore researchers have perfected an electron microscope to study fast-evolving material processes and chemical reactions. By applying engineering, microscopy, and laser expertise to the decades-old technology of electron microscopy, the dynamic transmission electron microscope (DTEM) team has developed a technique that can capture images of phenomena that are both very small and very fast. DTEM uses a precisely timed laser pulse to achieve a short but intense electron beam for imaging. When synchronized with a dynamic event in the microscope's field of view, DTEM allows scientists to record and measure material changes in action. A new movie-mode capability, which earned a 2013 R&D 100 Award from R&D Magazine, uses up to nine laser pulses to sequentially capture fast, irreversible, even one-of-a-kind material changes at the nanometer scale. DTEM projects are advancing basic and applied materials research, including such areas as nanostructure growth, phase transformations, and chemical reactions.

Energy-filtered real- and k-space secondary and energy-loss electron imaging with Dual Emission Electron spectro-Microscope: Cs/Mo(110).

PubMed

Grzelakowski, Krzysztof P

2016-05-01

Since its introduction the importance of complementary k||-space (LEED) and real space (LEEM) information in the investigation of surface science phenomena has been widely demonstrated over the last five decades. In this paper we report the application of a novel kind of electron spectromicroscope Dual Emission Electron spectroMicroscope (DEEM) with two independent electron optical channels for reciprocal and real space quasi-simultaneous imaging in investigation of a Cs covered Mo(110) single crystal by using the 800eV electron beam from an "in-lens" electron gun system developed for the sample illumination. With the DEEM spectromicroscope it is possible to observe dynamic, irreversible processes at surfaces in the energy-filtered real space and in the corresponding energy-filtered kǁ-space quasi-simultaneously in two independent imaging columns. The novel concept of the high energy electron beam sample illumination in the cathode lens based microscopes allows chemically selective imaging and analysis under laboratory conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparison of cross-sectional transmission electron microscope studies of thin germanium epilayers grown on differently oriented silicon wafers.

PubMed

Norris, D J; Myronov, M; Leadley, D R; Walther, T

2017-12-01

We compare transmission electron microscopical analyses of the onset of islanding in the germanium-on-silicon (Ge/Si) system for three different Si substrate orientations: (001), (11¯0) and (11¯1)Si. The Ge was deposited by reduced pressure chemical vapour deposition and forms islands on the surface of all Si wafers; however, the morphology (aspect ratio) of the deposited islands is different for each type of wafer. Moreover, the mechanism for strain relaxation is different for each type of wafer owing to the different orientation of the (111) slip planes with the growth surface. Ge grown on (001)Si is initially pseudomorphically strained, yielding small, almost symmetrical islands of high aspect ratio (clusters or domes) on top interdiffused SiGe pedestals, without any evidence of plastic relaxation by dislocations, which would nucleate later-on when the islands might have coalesced and then the Matthews-Blakeslee limit is reached. For (11¯0)Si, islands are flatter and more asymmetric, and this is correlated with plastic relaxation of some islands by dislocations. In the case of growth on (11¯1)Si wafers, there is evidence of immediate strain relaxation taking place by numerous dislocations and also twinning. In the case of untwined film/substrate interfaces, Burgers circuits drawn around certain (amorphous-like) regions show a nonclosure with an edge-type a/4[1¯12] Burgers vector component visible in projection along [110]. Microtwins of multiples of half unit cells in thickness have been observed which occur at the growth interface between the Si(11¯1) buffer layer and the overlying Ge material. Models of the growth mechanisms to explain the interfacial configurations of each type of wafer are suggested. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Development of a secondary electron energy analyzer for a transmission electron microscope.

PubMed

Magara, Hideyuki; Tomita, Takeshi; Kondo, Yukihito; Sato, Takafumi; Akase, Zentaro; Shindo, Daisuke

2018-04-01

A secondary electron (SE) energy analyzer was developed for a transmission electron microscope. The analyzer comprises a microchannel plate (MCP) for detecting electrons, a coil for collecting SEs emitted from the specimen, a tube for reducing the number of backscattered electrons incident on the MCP, and a retarding mesh for selecting the energy of SEs incident on the MCP. The detection of the SEs associated with charging phenomena around a charged specimen was attempted by performing electron holography and SE spectroscopy using the energy analyzer. The results suggest that it is possible to obtain the energy spectra of SEs using the analyzer and the charging states of a specimen by electron holography simultaneously.

Structural analysis of ion-implanted chemical-vapor-deposited diamond by transmission electron microscope

NASA Astrophysics Data System (ADS)

Jiang, N.; Deguchi, M.; Wang, C. L.; Won, J. H.; Jeon, H. M.; Mori, Y.; Hatta, A.; Kitabatake, M.; Ito, T.; Hirao, T.; Sasaki, T.; Hiraki, A.

1997-04-01

A transmission electron microscope (TEM) study of ion-implanted chemical-vapor-deposited (CVD) diamond is presented. CVD diamond used for transmission electron microscope observation was directly deposited onto Mo TEM grids. As-deposited specimens were irradiated by C (100 keV) ions at room temperature with a wide range of implantation doses (10 12-10 17/cm 2). Transmission electron diffraction (TED) patterns indicate that there exists a critical dose ( Dc) for the onset of amorphization of CVD diamond as a result of ion induced damage and the value of critical dose is confirmed to be about 3 × 10 15/cm 2. The ion-induced transformation process is clearly revealed by high resolution electron microscope (HREM) images. For a higher dose implantation (7 × 10 15/cm 2) a large amount of diamond phase is transformed into amorphous carbon and many tiny misoriented diamond blocks are found to be left in the amorphous solid. The average size of these misoriented diamond blocks is only about 1-2 nm. Further bombardment (10 17/cm 2) almost kills all of the diamond phase within the irradiated volume and moreover leads to local formation of micropolycrystalline graphite.

An investigation of nitride precipitates in archaeological iron artefacts from Poland.

PubMed

Kedzierski, Z; Stepiński, J; Zielińska-Lipiec, A

2010-03-01

The paper describes the investigations of nitride precipitates in a spearhead and a sword found in the territory of Poland, in cremation graveyards of the Przeworsk Culture, dated to the Roman Period. Three different techniques of the examination of nitride precipitates were employed: optical microscope, scanning electron microscope (scanning electron microscope with energy dispersive X-ray spectrometer) and transmission electron microscope. Two types of precipitates have been observed, and their plate-like shape was demonstrated. The large precipitate has been confirmed to be gamma'-Fe(4)N, whereas the small one has been identified as alpha''-Fe(16)N(2). The origin of nitride precipitates in archaeological iron artefacts from Poland is probably a result of the manufacturing process or cremation as part of burial rites. An examination of available iron artefacts indicates that nitride precipitates (have only limited effect on mechanical properties) influence the hardness of metal only to a very limited degree.

Aberration corrected 1.2-MV cold field-emission transmission electron microscope with a sub-50-pm resolution

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

Akashi, Tetsuya; Takahashi, Yoshio; Tanigaki, Toshiaki, E-mail: toshiaki.tanigaki.mv@hitachi.com

2015-02-16

Atomic-resolution electromagnetic field observation is critical to the development of advanced materials and to the unveiling of their fundamental physics. For this purpose, a spherical-aberration corrected 1.2-MV cold field-emission transmission electron microscope has been developed. The microscope has the following superior properties: stabilized accelerating voltage, minimized electrical and mechanical fluctuation, and coherent electron emission. These properties have enabled to obtain 43-pm information transfer. On the bases of these performances, a 43-pm resolution has been obtained by correcting lens aberrations up to the third order. Observations of GaN [411] thin crystal showed a projected atomic locations with a separation of 44 pm.

Indentation-Enabled In Situ Mechanical Characterization of Micro/Nanopillars in Electron Microscopes

NASA Astrophysics Data System (ADS)

Guo, Qiang; Fu, Xidan; Guo, Xiaolei; Liu, Zhiying; Shi, Yan; Zhang, Di

2018-04-01

Indentation-enabled micro/nanomechanical characterization of small-scale specimens provides powerful new tools for probing materials properties that were once unattainable by conventional experimental methods. Recent advancement in instrumentation further allows mechanical testing to be carried out in situ in electron microscopes, with high spatial and temporal resolution. This review discusses the recent development of nanoindentation-enabled in situ mechanical testing in electron microscopes, with an emphasis on the study of micro/nanopillars. Focus is given to novel applications beyond simple compressive and tensile testing that have been developed in the past few years, and limitations and possible future research directions in this field are proposed and discussed.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P [Los Alamos, NM; Chernobrod, Boris M [Los Alamos, NM

2010-06-29

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P.; Chernobrod, Boris M.

2009-11-10

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of impaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P.; Chernobrod, Boris M.

2007-12-11

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P [Los Alamos, NM; Chernobrod, Boris M [Los Alamos, NM

2010-07-13

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Spin microscope based on optically detected magnetic resonance

DOEpatents

Berman, Gennady P [Los Alamos, NM; Chernobrod, Boris M [Los Alamos, NM

2009-10-27

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Effects of gamma radiation on hard dental tissues of albino rats using scanning electron microscope - Part 1

NASA Astrophysics Data System (ADS)

El-Faramawy, Nabil; Ameen, Reham; El-Haddad, Khaled; Maghraby, Ahmed; El-Zainy, Medhat

2011-12-01

In the present study, 40 adult male albino rats were used to study the effect of gamma radiation on the hard dental tissues (enamel surface, dentinal tubules and the cementum surface). The rats were irradiated at 0.2, 0.5, 1.0, 2.0, 4.0 and 6.0 Gy gamma doses. The effects of irradiated hard dental tissues samples were investigated using a scanning electron microscope. For doses up to 0.5 Gy, there was no evidence of the existence of cracks on the enamel surface. With 1 Gy irradiation dose, cracks were clearly observed with localized erosive areas. At 2 Gy irradiation dose, the enamel showed morphological alterations as disturbed prismatic and interprismatic areas. An increase in dentinal tubules diameter and a contemporary inter-tubular dentine volume decrease were observed with higher irradiation dose. Concerning cementum, low doses,<0.5 Gy, showed surface irregularities and with increase in the irradiation dose to≥1 Gy, noticeable surface irregularities and erosive areas with decrease in Sharpey's fiber sites were observed. These observations could shed light on the hazardous effects of irradiation fields to the functioning of the human teeth.

Preparation of hierarchical porous Zn-salt particles and their superhydrophobic performance

NASA Astrophysics Data System (ADS)

Gao, Dahai; Jia, Mengqiu

2015-12-01

Superhydrophobic surfaces arranged by hierarchical porous particles were prepared using modified hydrothermal routes under the effect of sodium citrate. Two particle samples were generated in the medium of hexamethylenetetramine (P1) and urea (P2), respectively. X-ray diffraction, scanning electron microscope, and transmission electron microscope were adopted for the investigation, and results revealed that the P1 and P2 particles are porous microspheres with crosslinked extremely thin (10-30 nm) sheet crystals composed of Zn5(OH)8Ac2·2H2O and Zn5(CO3)2(OH)6, respectively. The prepared particles were treated with a fluoroethylene vinyl ether derivative and studied using Fourier transform infrared spectroscopy and energy-dispersive X-ray spectrometer. Results showed that the hierarchical surfaces of these particles were combined with low-wettable fluorocarbon layers. Moreover, the fabricated surface composed of the prepared hierarchical particles displayed considerably high contact angles, indicating great superhydrophobicity for the products. The wetting behavior of the particles was analyzed with a theoretical wetting model in comparison with that of chestnut-like ZnO products obtained through a conventional hydrothermal route. Correspondingly, this study provided evidence that high roughness surface plays a great role in superhydrophobic behavior.

Atomic force microscopic imaging of Acanthamoeba castellanii and Balamuthia mandrillaris trophozoites and cysts.

PubMed

Aqeel, Yousuf; Siddiqui, Ruqaiyyah; Ateeq, Muhammad; Raza Shah, Muhammad; Kulsoom, Huma; Khan, Naveed Ahmed

2015-01-01

Light microscopy and electron microscopy have been successfully used in the study of microbes, as well as free-living protists. Unlike light microscopy, which enables us to observe living organisms or the electron microscope which provides a two-dimensional image, atomic force microscopy provides a three-dimensional surface profile. Here, we observed two free-living amoebae, Acanthamoeba castellanii and Balamuthia mandrillaris under the phase contrast inverted microscope, transmission electron microscope and atomic force microscope. Although light microscopy was of lower magnification, it revealed functional biology of live amoebae such as motility and osmoregulation using contractile vacuoles of the trophozoite stage, but it is of limited value in defining the cyst stage. In contrast, transmission electron microscopy showed significantly greater magnification and resolution to reveal the ultra-structural features of trophozoites and cysts including intracellular organelles and cyst wall characteristics but it only produced a snapshot in time of a dead amoeba cell. Atomic force microscopy produced three-dimensional images providing detailed topographic description of shape and surface, phase imaging measuring boundary stiffness, and amplitude measurements including width, height and length of A. castellanii and B. mandrillaris trophozoites and cysts. These results demonstrate the importance of the application of various microscopic methods in the biological and structural characterization of the whole cell, ultra-structural features, as well as surface components and cytoskeleton of protist pathogens. © 2014 The Author(s) Journal of Eukaryotic Microbiology © 2014 International Society of Protistologists.

Scanning electron microscope view of iron crystal growing on pyroxene crystal

NASA Technical Reports Server (NTRS)

1972-01-01

A scanning electron microscope photograph of a four-micron size iron crystal growing on a pyroxene crystal (calcium-magnesium-iron silicate) from the Apollo 15 Hadley-Apennino lunar landing site. The well developed crystal faces indicate that the crystal was formed from a hot vapor as the rock was cooling.

Arc-melting preparation of single crystal LaB.sub.6 cathodes

DOEpatents

Gibson, Edwin D.; Verhoeven, John D.

1977-06-21

A method for preparing single crystals of lanthanum hexaboride (LaB.sub.6) by arc melting a rod of compacted LaB.sub.6 powder. The method is especially suitable for preparing single crystal LaB.sub.6 cathodes for use in scanning electron microscopes (SEM) and scanning transmission electron microscopes (STEM).

Deciphering the physics and chemistry of perovskites with transmission electron microscopy.

PubMed

Polking, Mark J

2016-03-28

Perovskite oxides exhibit rich structural complexity and a broad range of functional properties, including ferroelectricity, ferromagnetism, and superconductivity. The development of aberration correction for the transmission electron microscope and concurrent progress in electron spectroscopy, electron holography, and other techniques has fueled rapid progress in the understanding of the physics and chemistry of these materials. New techniques based on the transmission electron microscope are first surveyed, and the applications of these techniques for the study of the structure, chemistry, electrostatics, and dynamics of perovskite oxides are then explored in detail, with a particular focus on ferroelectric materials.

Microfossils in Carbonaceous Meteorites

NASA Technical Reports Server (NTRS)

Hoover, Richard B.

2009-01-01

Microfossils of large filamentous trichomic prokaryotes have been detected during in-situ investigations of carbonaceous meteorites. This research has been carried out using the Field Emission Scanning Electron Microscope (FESEM) to examine freshly fractured interior surfaces of the meteorites. The images obtained reveal that many of these remains are embedded in the meteorite rock matrix. Energy Dispersive X-Ray Spectroscopy (EDS) studies establish that the filamentous microstructures have elemental compositions consistent with the meteorite matrix, but are often encased within carbon-rich electron transparent sheath-like structures infilled with magnesium sulfate. This is consistent with the taphonomic modes of fossilization of cyanobacteria and sulphur bacteria, since the life habits and processes of these microorganisms frequently result in distinctive chemical biosignatures associated with the properties of their cell-walls, trichomes, and the extracellular polymeric substances (EPS) of the sheath. In this paper the evidence for biogenicity presented includes detailed morphological and morphometric data consistent with known characteristics of uniseriate and multiseriate cyanobacteria. Evidence for indigeneity includes the embedded nature of the fossils and elemental compositions inconsistent with modern biocontaminants.

Wear effects on microscopic morphology and hyaluronan uptake in siloxane-hydrogel contact lenses.

PubMed

Tavazzi, Silvia; Tonveronachi, Martina; Fagnola, Matteo; Cozza, Federica; Ferraro, Lorenzo; Borghesi, Alessandro; Ascagni, Miriam; Farris, Stefano

2015-07-01

The purpose of this study was a comparison between new and worn siloxane-hydrogel contact lenses in terms of microscopic structure, surface morphology, and loading of hyaluronan. The analyses were performed by scanning electron microscopy, with the support of the freeze-drying technique, and by fluorescence confocal microscopy. Along the depth profile of new lenses, a thin porous top layer was observed, which corresponds to the region of hyaluronan penetration inside well-defined channels. The time evolution was followed from one day to two weeks of daily wear, when a completely different scenario was found. Clear experimental evidence of a buggy surface was observed with several crests and regions of swelling, which could be filled by the hyaluronan solution. The modifications are attributed to the progressive relaxation of the structure of the polymeric network. © 2014 Wiley Periodicals, Inc.

Tailoring the morphology of raspberry-like carbon black/polystyrene composite microspheres for fabricating superhydrophobic surface

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

Bao, Yubin; Li, Qiuying, E-mail: liqy@ecust.edu.cn; Shanghai Key Laboratory Polymeric Materials

In our previous report, raspberry-like carbon black/polystyrene (CB/PS) composite microsphere was prepared through heterocoagulation process. Based on the previous study, in the present work, the morphology of raspberry-like CB/PS particle is tailored through adjusting the polarity and the concentration ratio of CB/PS colloidal suspension with the purpose to prepare particulate film for the fabrication of superhydrophobic surface. Scanning electron microscope (SEM) confirms the morphology of raspberry-like particle and the coverage of CB. Rough surfaces fabricated by raspberry-like particles with proper morphology are observed by SEM and clear evidence of superhydrophobic surface is shown. The structure of raspberry-like particle is analyzedmore » by atom force microscope. The proposed relationship between the hydrophobicity and the structure of CB aggregates on the surface of PS microsphere is discussed in details.« less

Time-resolved electric force microscopy of charge traps in polycrystalline pentacene films

NASA Astrophysics Data System (ADS)

Jaquith, Michael; Muller, Erik; Marohn, John

2006-03-01

The microscopic mechanisms by which charges trap in organic electronic materials are poorly understood. Muller and Marohn recently showed that electric force microscopy (EFM) can be used to image trapped charge in working pentacene thin-film transistors [E. M. Muller et al, Adv. Mater. 17 1410 (2005)]. We have extended their work by imaging trapped charge in pentacene films with much larger grains. In contrast to the previous study in which charge was found to trap inhomogeneously throughout the transistor gap, we find microscopic evidence for a new trapping mechanism in which charges trap predominantly at the pentacene/metal interface in large-grained devices. We have also made localized measurements of the trap growth over time by performing pulsed-gate EFM experiments. Integrated-rate kinetics data supports a charge trap mechanism which is second order in holes, e.g., holes trap in pairs, although the charge-trapping rate appears to depend on gate voltage.

Source brightness and useful beam current of carbon nanotubes and other very small emitters

NASA Astrophysics Data System (ADS)

Kruit, P.; Bezuijen, M.; Barth, J. E.

2006-01-01

The potential application of carbon nanotubes as electron sources in electron microscopes is analyzed. The resolution and probe current that can be obtained from a carbon nanotube emitter in a low-voltage scanning electron microscope are calculated and compared to the state of the art using Schottky electron sources. Many analytical equations for probe-size versus probe-current relations in different parameter regimes are obtained. It is shown that for most carbon nanotube emitters, the gun lens aberrations are larger than the emitters' virtual source size and thus restrict the microscope's performance. The result is that the advantages of the higher brightness of nanotube emitters are limited unless the angular emission current is increased over present day values or the gun lens aberrations are decreased. For some nanotubes with a closed cap, it is known that the emitted electron beam is coherent over the full emission cone. We argue that for such emitters the parameter ``brightness'' becomes meaningless. The influence of phase variations in the electron wave front emitted from such a nanotube emitter on the focusing of the electron beam is analyzed.

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

PubMed

Walther, Paul; Schmid, Eberhard; Höhn, Katharina

2013-01-01

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

Transmission environmental scanning electron microscope with scintillation gaseous detection device.

PubMed

Danilatos, Gerasimos; Kollia, Mary; Dracopoulos, Vassileios

2015-03-01

A transmission environmental scanning electron microscope with use of a scintillation gaseous detection device has been implemented. This corresponds to a transmission scanning electron microscope but with addition of a gaseous environment acting both as environmental and detection medium. A commercial type of low vacuum machine has been employed together with appropriate modifications to the detection configuration. This involves controlled screening of various emitted signals in conjunction with a scintillation gaseous detection device already provided with the machine for regular surface imaging. Dark field and bright field imaging has been obtained along with other detection conditions. With a progressive series of modifications and tests, the theory and practice of a novel type of microscopy is briefly shown now ushering further significant improvements and developments in electron microscopy as a whole. Copyright © 2014 Elsevier B.V. All rights reserved.

Self-assembly of chlorophenols in water

PubMed Central

Rogalska, Ewa; Rogalski, Marek; Gulik-Krzywicki, Tadeusz; Gulik, Annette; Chipot, Christophe

1999-01-01

In saturated solutions of some di- and trichlorophenols, structures with complex morphologies, consisting of thin, transparent sheets often coiling into helices and ultimately twisting into filaments, were observed under the optical microscope. Freeze-fracture electron microscopy, x-ray diffraction, phase diagrams, and molecular modeling were performed to elucidate the observed phenomena. Here, we present evidence that the chlorophenols studied, when interacting with water, self-assemble into bilayers. The fact that some chlorophenols form the same supramolecular structures as those described previously for structurally nonrelated surfactants sheds light on the mechanisms of self-assembly. PMID:10359753

Physics and engineering aspects of cell and tissue imaging systems: microscopic devices and computer assisted diagnosis.

PubMed

Chen, Xiaodong; Ren, Liqiang; Zheng, Bin; Liu, Hong

2013-01-01

The conventional optical microscopes have been used widely in scientific research and in clinical practice. The modern digital microscopic devices combine the power of optical imaging and computerized analysis, archiving and communication techniques. It has a great potential in pathological examinations for improving the efficiency and accuracy of clinical diagnosis. This chapter reviews the basic optical principles of conventional microscopes, fluorescence microscopes and electron microscopes. The recent developments and future clinical applications of advanced digital microscopic imaging methods and computer assisted diagnosis schemes are also discussed.

Analysis of microscopic parameters of surface charging in polymer caused by defocused electron beam irradiation.

PubMed

Liu, Jing; Zhang, Hai-Bo

2014-12-01

The relationship between microscopic parameters and polymer charging caused by defocused electron beam irradiation is investigated using a dynamic scattering-transport model. The dynamic charging process of an irradiated polymer using a defocused 30 keV electron beam is conducted. In this study, the space charge distribution with a 30 keV non-penetrating e-beam is negative and supported by some existing experimental data. The internal potential is negative, but relatively high near the surface, and it decreases to a maximum negative value at z=6 μm and finally tend to 0 at the bottom of film. The leakage current and the surface potential behave similarly, and the secondary electron and leakage currents follow the charging equilibrium condition. The surface potential decreases with increasing beam current density, trap concentration, capture cross section, film thickness and electron-hole recombination rate, but with decreasing electron mobility and electron energy. The total charge density increases with increasing beam current density, trap concentration, capture cross section, film thickness and electron-hole recombination rate, but with decreasing electron mobility and electron energy. This study shows a comprehensive analysis of microscopic factors of surface charging characteristics in an electron-based surface microscopy and analysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fully kinetic simulations of collisionless, mesothermal plasma emission: Macroscopic plume structure and microscopic electron characteristics

NASA Astrophysics Data System (ADS)

Hu, Yuan; Wang, Joseph

2017-03-01

This paper presents a fully kinetic particle particle-in-cell simulation study on the emission of a collisionless plasma plume consisting of cold beam ions and thermal electrons. Results are presented for both the two-dimensional macroscopic plume structure and the microscopic electron kinetic characteristics. We find that the macroscopic plume structure exhibits several distinctive regions, including an undisturbed core region, an electron cooling expansion region, and an electron isothermal expansion region. The properties of each region are determined by microscopic electron kinetic characteristics. The division between the undisturbed region and the cooling expansion region approximately matches the Mach line generated at the edge of the emission surface, and that between the cooling expansion region and the isothermal expansion region approximately matches the potential well established in the beam. The interactions between electrons and the potential well lead to a new, near-equilibrium state different from the initial distribution for the electrons in the isothermal expansion region. The electron kinetic characteristics in the plume are also very anisotropic. As the electron expansion process is mostly non-equilibrium and anisotropic, the commonly used assumption that the electrons in a collisionless, mesothermal plasma plume may be treated as a single equilibrium fluid in general is not valid.

Analysis with electron microscope of multielement samples using pure element standards

DOEpatents

King, Wayne E.

1987-01-01

A method and modified analytical electron microscope for determining the concentration of elements in a multielement sample by exposing samples with differing thicknesses for each element to a beam of electrons, simultaneously measuring the electron dosage and x-ray intensities for each sample of element to determine a "K.sub.AB " value to be used in the equation ##EQU1## where I is intensity and C is concentration for elements A and B, and exposing the multielement sample to determine the concentrations of the elements in the sample.

Rapid and precise scanning helium ion microscope milling of solid-state nanopores for biomolecule detection.

PubMed

Yang, Jijin; Ferranti, David C; Stern, Lewis A; Sanford, Colin A; Huang, Jason; Ren, Zheng; Qin, Lu-Chang; Hall, Adam R

2011-07-15

We report the formation of solid-state nanopores using a scanning helium ion microscope. The fabrication process offers the advantage of high sample throughput along with fine control over nanopore dimensions, producing single pores with diameters below 4 nm. Electronic noise associated with ion transport through the resultant pores is found to be comparable with levels measured on devices made with the established technique of transmission electron microscope milling. We demonstrate the utility of our nanopores for biomolecular analysis by measuring the passage of double-strand DNA.

Intrinsic instability of aberration-corrected electron microscopes.

PubMed

Schramm, S M; van der Molen, S J; Tromp, R M

2012-10-19

Aberration-corrected microscopes with subatomic resolution will impact broad areas of science and technology. However, the experimentally observed lifetime of the corrected state is just a few minutes. Here we show that the corrected state is intrinsically unstable; the higher its quality, the more unstable it is. Analyzing the contrast transfer function near optimum correction, we define an "instability budget" which allows a rational trade-off between resolution and stability. Unless control systems are developed to overcome these challenges, intrinsic instability poses a fundamental limit to the resolution practically achievable in the electron microscope.

Thermophysical ESEM and TEM Characterization of Carbon Fibers CTE, Spectroscopy and Roughness Studies at High Temperatures

NASA Technical Reports Server (NTRS)

Ochoa, Ozden O.

2004-01-01

Accurate determination of the transverse properties of carbon fibers is important for assessment and prediction of local material as well as global structural response of composite components. However the measurements are extremely difficult due to the very small diameters of the fibers (few microns only) and must be conducted within a microscope. In this work, environmental scanning electron microscope (ESEM) and transmission electron microscope (TEM) are used to determine the transverse coefficient of thermal expansion of different carbon fibers as a function of temperature.

Electron beam dynamics in an ultrafast transmission electron microscope with Wehnelt electrode.

PubMed

Bücker, K; Picher, M; Crégut, O; LaGrange, T; Reed, B W; Park, S T; Masiel, D J; Banhart, F

2016-12-01

High temporal resolution transmission electron microscopy techniques have shown significant progress in recent years. Using photoelectron pulses induced by ultrashort laser pulses on the cathode, these methods can probe ultrafast materials processes and have revealed numerous dynamic phenomena at the nanoscale. Most recently, the technique has been implemented in standard thermionic electron microscopes that provide a flexible platform for studying material's dynamics over a wide range of spatial and temporal scales. In this study, the electron pulses in such an ultrafast transmission electron microscope are characterized in detail. The microscope is based on a thermionic gun with a Wehnelt electrode and is operated in a stroboscopic photoelectron mode. It is shown that the Wehnelt bias has a decisive influence on the temporal and energy spread of the picosecond electron pulses. Depending on the shape of the cathode and the cathode-Wehnelt distance, different emission patterns with different pulse parameters are obtained. The energy spread of the pulses is determined by space charge and Boersch effects, given by the number of electrons in a pulse. However, filtering effects due to the chromatic aberrations of the Wehnelt electrode allow the extraction of pulses with narrow energy spreads. The temporal spread is governed by electron trajectories of different length and in different electrostatic potentials. High temporal resolution is obtained by excluding shank emission from the cathode and aberration-induced halos in the emission pattern. By varying the cathode-Wehnelt gap, the Wehnelt bias, and the number of photoelectrons in a pulse, tradeoffs between energy and temporal resolution as well as beam intensity can be made as needed for experiments. Based on the characterization of the electron pulses, the optimal conditions for the operation of ultrafast TEMs with thermionic gun assembly are elaborated. Copyright © 2016 Elsevier B.V. All rights reserved.

Vacuum Ultraviolet (VUV) radiation-induced degradation of Fluorinated Ethylene Propylene (FEP) Teflon aboard the Long Duration Exposure Facility (LDEF)

NASA Technical Reports Server (NTRS)

Brinza, David E.; Stiegman, A. E.; Staszak, Paul R.; Laue, Eric G.; Liang, Ranty H.

1992-01-01

Examination of fluorinated ethylene propylene (FEP) copolymer specimens recovered from the Long Duration Exposure Facility (LDEF) provides evidence for degradation attributed to extended solar vacuum ultraviolet (VUV) irradiation. Scanning electron microscope (SEM) images of sheared FEP film edges reveal the presence of a highly embrittled layer on the exposed surface of specimens obtained from the trailing edge of the LDEF. Similar images obtained for leading edge and control FEP films do not exhibit evidence for such an embrittled layer. Laboratory VUV irradiation of FEP films is found to produce a damage layer similar to that witnessed in the LDEF trailing edge films. Spectroscopic analyses of irradiated films provide data to advance a photochemical mechanism for degradation.

Dose-rate-dependent damage of cerium dioxide in the scanning transmission electron microscope.

PubMed

Johnston-Peck, Aaron C; DuChene, Joseph S; Roberts, Alan D; Wei, Wei David; Herzing, Andrew A

2016-11-01

Beam damage caused by energetic electrons in the transmission electron microscope is a fundamental constraint limiting the collection of artifact-free information. Through understanding the influence of the electron beam, experimental routines may be adjusted to improve the data collection process. Investigations of CeO 2 indicate that there is not a critical dose required for the accumulation of electron beam damage. Instead, measurements using annular dark field scanning transmission electron microscopy and electron energy loss spectroscopy demonstrate that the onset of measurable damage occurs when a critical dose rate is exceeded. The mechanism behind this phenomenon is that oxygen vacancies created by exposure to a 300keV electron beam are actively annihilated as the sample re-oxidizes in the microscope environment. As a result, only when the rate of vacancy creation exceeds the recovery rate will beam damage begin to accumulate. This observation suggests that dose-intensive experiments can be accomplished without disrupting the native structure of the sample when executed using dose rates below the appropriate threshold. Furthermore, the presence of an encapsulating carbonaceous layer inhibits processes that cause beam damage, markedly increasing the dose rate threshold for the accumulation of damage. Published by Elsevier B.V.

Dose-rate-dependent damage of cerium dioxide in the scanning transmission electron microscope

PubMed Central

Johnston-Peck, Aaron C.; DuChene, Joseph S.; Roberts, Alan D.; Wei, Wei David; Herzing, Andrew A.

2016-01-01

Beam damage caused by energetic electrons in the transmission electron microscope is a fundamental constraint limiting the collection of artifact-free information. Through understanding the influence of the electron beam, experimental routines may be adjusted to improve the data collection process. Investigations of CeO2 indicate that there is not a critical dose required for the accumulation of electron beam damage. Instead, measurements using annular dark field scanning transmission electron microscopy and electron energy loss spectroscopy demonstrate that the onset of measurable damage occurs when a critical dose rate is exceeded. The mechanism behind this phenomenon is that oxygen vacancies created by exposure to a 300 keV electron beam are actively annihilated as the sample re-oxidizes in the microscope environment. As a result, only when the rate of vacancy creation exceeds the recovery rate will beam damage begin to accumulate. This observation suggests that dose-intensive experiments can be accomplished without disrupting the native structure of the sample when executed using dose rates below the appropriate threshold. Furthermore, the presence of an encapsulating carbonaceous layer inhibits processes that cause beam damage, markedly increasing the dose rate threshold for the accumulation of damage. PMID:27469265

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

PubMed

Saladra, Dawid; Kopernik, Magdalena

2016-10-01

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

[Microscopic investigation of vessel wall after endovascular catheter atherectomy].

PubMed

Tsygankov, V N; Khovalkin, R G; Chekmareva, I A; Kalinin, D V; Filippova, E M

2014-01-01

Endovascular target catheter atherectomy (ETCA) - method of artery patency allowing to obtain occlusion substrate. Given the high destructive effect of atherectome's elements on tissue the objective was determination possibility of histological and electron microscopic investigation of this substrate after atherectomy. The research included 8 patients who underwent ETCA of legs arteries. It was observed substrate removal from broken stent in 1 case. 2 of 8 patients had diabetes. Obtained substrate was available for histological and electron microscopic investigation. Atherosclerosis was confirmed in all cases. It was not observed substrate significant morphological changes in patients with presence or absence of diabetes. Microscopic investigation of substrate from broken stent shows pronounced development of granulation tissue that was regarded as special form of reparative regeneration. Finding internal elastic membrane during microscopic investigation in some cases proves radical intervention. The authors consider that microscopic investigation of substrate after ETCA may be used for diagnosis verification, thorough analysis of morphological changes in lesion area and radicalism of atherectomy.

Isotope analysis in the transmission electron microscope.

PubMed

Susi, Toma; Hofer, Christoph; Argentero, Giacomo; Leuthner, Gregor T; Pennycook, Timothy J; Mangler, Clemens; Meyer, Jannik C; Kotakoski, Jani

2016-10-10

The Ångström-sized probe of the scanning transmission electron microscope can visualize and collect spectra from single atoms. This can unambiguously resolve the chemical structure of materials, but not their isotopic composition. Here we differentiate between two isotopes of the same element by quantifying how likely the energetic imaging electrons are to eject atoms. First, we measure the displacement probability in graphene grown from either 12 C or 13 C and describe the process using a quantum mechanical model of lattice vibrations coupled with density functional theory simulations. We then test our spatial resolution in a mixed sample by ejecting individual atoms from nanoscale areas spanning an interface region that is far from atomically sharp, mapping the isotope concentration with a precision better than 20%. Although we use a scanning instrument, our method may be applicable to any atomic resolution transmission electron microscope and to other low-dimensional materials.

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

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

Zaka, F.

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

Microscopic investigation of cavitation erosion damage in metals

NASA Technical Reports Server (NTRS)

Hackworh, J. V.; Adler, W. F.

1974-01-01

The results of research to identify the cavitation erosion damage mechanisms at the microscopic level for three metals (aluminum, stainless steel, and titanium) representing a range of properties and microstructure are presented. The metals were exposed to cavitation generated in distilled water by a 20-kHz ultrasonic facility operating at a vibration amplitude of 2 mils. Representative properties of the metals and experimental details are summarized. Replicas of the eroded surfaces of the specimens obtained periodically during exposure were examined with a transmission electron microscope to follow progression of the erosion damage and identify dominant erosion mechanisms as a function of exposure time. Eroded surfaces of selected specimens were also examined with a scanning electron microscope to assist in the interpretation.

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

DOEpatents

de Jonge, Niels [Oak Ridge, TN

2010-08-17

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

Electron microscope phase enhancement

DOEpatents

Jin, Jian; Glaeser, Robert M.

2010-06-15

A microfabricated electron phase shift element is used for modifying the phase characteristics of an electron beam passing though its center aperture, while not affecting the more divergent portion of an incident beam to selectively provide a ninety-degree phase shift to the unscattered beam in the back focal plan of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. One application of the element is to increase the contrast of an electron microscope for viewing weakly scattering samples while in focus. Typical weakly scattering samples include biological samples such as macromolecules, or perhaps cells. Preliminary experimental images demonstrate that these devices do apply a ninety degree phase shift as expected. Electrostatic calculations have been used to determine that fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size aperture is about 5:1. Calculations are underway to determine the feasibility of aspect smaller aspect ratios of about 3:1 and about 2:1.

Mars Life? - Microscopic Structures

NASA Image and Video Library

1996-08-09

In the center of this electron microscope image of a small chip from a meteorite are several tiny structures that are possible microscopic fossils of primitive, bacteria-like organisms that may have lived on Mars more than 3.6 billion years ago. http://photojournal.jpl.nasa.gov/catalog/PIA00283

A Conspicuous Clay Ovoid in Nakhla: Evidence for Subsurface Hydrothermal Alteration on Mars with Implications for Astrobiology

PubMed Central

Haigh, Sarah; Lyon, Ian

2014-01-01

Abstract A conspicuous biomorphic ovoid structure has been discovered in the Nakhla martian meteorite, made of nanocrystalline iron-rich saponitic clay and amorphous material. The ovoid is indigenous to Nakhla and occurs within a late-formed amorphous mesostasis region of rhyolitic composition that is interstitial to two clinopyroxene grains with Al-rich rims, and contains acicular apatite crystals, olivine, sulfides, Ti-rich magnetite, and a new mineral of the rhoenite group. To infer the origin of the ovoid, a large set of analytical tools was employed, including scanning electron microscopy and backscattered electron imaging, wavelength-dispersive X-ray analysis, X-ray mapping, Raman spectroscopy, time-of-flight secondary ion mass spectrometry analysis, high-resolution transmission electron microscope imaging, and atomic force microscope topographic mapping. The concentric wall of the ovoid surrounds an originally hollow volume and exhibits internal layering of contrasting nanotextures but uniform chemical composition, and likely inherited its overall shape from a preexisting vesicle in the mesostasis glass. A final fibrous layer of Fe-rich phases blankets the interior surfaces of the ovoid wall structure. There is evidence that the parent rock of Nakhla has undergone a shock event from a nearby bolide impact that melted the rims of pyroxene and the interstitial matter and initiated an igneous hydrothermal system of rapidly cooling fluids, which were progressively mixed with fluids from the melted permafrost. Sharp temperature gradients were responsible for the crystallization of Al-rich clinopyroxene rims, rhoenite, acicular apatites, and the quenching of the mesostasis glass and the vesicle. During the formation of the ovoid structure, episodic fluid infiltration events resulted in the precipitation of saponite rinds around the vesicle walls, altered pyrrhotite to marcasite, and then isolated the ovoid wall structure from the rest of the system by depositing a layer of iron oxides/hydroxides. Carbonates, halite, and sulfates were deposited last within interstitial spaces and along fractures. Among three plausible competing hypotheses here, this particular abiotic scenario is considered to be the most reasonable explanation for the formation of the ovoid structure in Nakhla, and although compelling evidence for a biotic origin is lacking, it is evident that the martian subsurface contains niche environments where life could develop. Key Words: Biomorph—Clays—Search for life (biosignatures)—Martian meteorites—Hydrothermal systems. Astrobiology 14, 651–693. PMID:25046549

Concurrent in situ ion irradiation transmission electron microscope

DOE PAGES

Hattar, K.; Bufford, D. C.; Buller, D. L.

2014-08-29

An in situ ion irradiation transmission electron microscope has been developed and is operational at Sandia National Laboratories. This facility permits high spatial resolution, real time observation of electron transparent samples under ion irradiation, implantation, mechanical loading, corrosive environments, and combinations thereof. This includes the simultaneous implantation of low-energy gas ions (0.8–30 keV) during high-energy heavy ion irradiation (0.8–48 MeV). In addition, initial results in polycrystalline gold foils are provided to demonstrate the range of capabilities.

Ultrastructural analysis of dental ceramic surface processed by a 1070 nm fiber laser

NASA Astrophysics Data System (ADS)

Fornaini, C.; Merigo, E.; Poli, F.; Rocca, J.-P.; Selleri, S.; Cucinotta, A.

2018-04-01

Background: Lithium di-silicate dental ceramic bonding, realized by using different resins, is strictly dependent on micro-mechanical retention and chemical adhesion. The aim of this in vitro study was to investigate the capability of a 1070 nm fibre laser for their surface treatment. Methods: Samples were irradiated by a pulsed fibre laser at 1070 nm with different parameters (peak power of 5, 7.5, and 10 kW, repetition rate (RR) 20 kHz, speed of 10 and 50 mm/sec, and total energy density from 1.3 to 27 kW/cm2) Subsequently, the surface modifications were analysed by optical microscope, scanning electron microscope (SEM) and energy dispersive X-ray Spectroscopy (EDS). Results: With a peak power of 5 kW, RR of 20 kHz, and speed of 50 mm/sec, the microscopic observation of the irradiated surface showed increased roughness with small areas of melting and carbonization. EDS analysis revealed that, with these parameters, there are no evident differences between laser-processed samples and controls. Conclusions: A 1070 nm fibre laser can be considered as a good device to increase the adhesion of lithium di-silicate ceramics when optimum parameters are considered.

Confirmation of thalamosubthalamic projections by electron microscopic autoradiography.

PubMed

Sugimoto, T; Hattori, T

1983-05-16

Direct projections from the centre median-parafascicular complex (CM-Pf) to the subthalamic nucleus(STN) were confirmed by electron microscopic autoradiography. [3H]Leucine injections into the rat CM-Pf produced preferential labeling of Gray's type I boutons containing round vesicles in the ipsilateral STN. Further results strongly suggested the existence of some common CM-Pf projections to both the striatum and STN.

Collection and Analysis of Aircraft Emitted Particles

NASA Technical Reports Server (NTRS)

Wilson, James Charles

1999-01-01

The University of Denver Aerosol Group proposed to adapt an impactor system for the collection of particles emitted by aircraft. The collection substrates were electron microscope grids which were analyzed by Dr. Pat Sheridan using a transmission electron microscope. The impactor was flown in the SNIFF behind aircraft and engine emissions were sampled. This report details the results of that work.

Foucault imaging by using non-dedicated transmission electron microscope

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

Taniguchi, Yoshifumi; Matsumoto, Hiroaki; Harada, Ken

2012-08-27

An electron optical system for observing Foucault images was constructed using a conventional transmission electron microscope without any special equipment for Lorentz microscopy. The objective lens was switched off and an electron beam was converged by a condenser optical system to the crossover on the selected area aperture plane. The selected area aperture was used as an objective aperture to select the deflected beam for Foucault mode, and the successive image-forming lenses were controlled for observation of the specimen images. The irradiation area on the specimen was controlled by selecting the appropriate diameter of the condenser aperture.

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

PubMed

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

2015-03-01

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

Review of current progress in nanometrology with the helium ion microscope

NASA Astrophysics Data System (ADS)

Postek, Michael T.; Vladár, András; Archie, Charles; Ming, Bin

2011-02-01

Scanning electron microscopy has been employed as an imaging and measurement tool for more than 50 years and it continues as a primary tool in many research and manufacturing facilities across the world. A new challenger to this work is the helium ion microscope (HIM). The HIM is a new imaging and metrology technology. Essentially, substitution of the electron source with a helium ion source yields a tool visually similar in function to the scanning electron microscope, but very different in the fundamental imaging and measurement process. The imaged and measured signal originates differently than in the scanning electron microscope and that fact and its single atom source diameter may be able to push the obtainable resolution lower, provide greater depth-of-field and ultimately improve the metrology. Successful imaging and metrology with this instrument entails understanding and modeling of new ion beam/specimen interaction physics. As a new methodology, HIM is beginning to show promise and the abundance of potentially advantageous applications for nanometrology has yet to be fully exploited. This paper discusses some of the progress made at NIST in collaboration with IBM to understand the science behind this new technology.

Fabrication of large area plasmonic nanoparticle grating structure on silver halide based transmission electron microscope film and its application as a surface enhanced Raman spectroscopy substrate

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

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

The plasmonic responses of silver nanoparticle grating structures of different periods made on silver halide based electron microscope film are investigated. Raster scan of the conventional scanning electron microscope (SEM) is used to carry out electron beam lithography for fabricating the plasmonic nanoparticle grating (PNG) structures. Morphological characterization of the PNG structures, carried out by the SEM and the atomic force microscope, indicates that the depth of the groove decreases with a decrease in the grating period. Elemental characterization performed by the energy dispersive spectroscopy and the x-ray diffraction shows the presence of nanoparticles of silver in the PNG grating.more » The optical characterization of the gratings shows that the localized surface plasmon resonance peak shifts from 366 to 378 nm and broadens with a decrease in grating period from 10 to 2.5 μm. The surface enhanced Raman spectroscopy of the Rhodamine-6G dye coated PNG structure shows the maximum enhancement by two orders of magnitude in comparison to the randomly distributed silver nanoparticles having similar size and shape as the PNG structure.« less

Preparation of polymeric Janus particles by directional UV-induced reactions.

PubMed

Liu, Lianying; Ren, Mingwei; Yang, Wantai

2009-09-15

Polymeric Janus particles are obtained by UV-induced selective surface grafting polymerizations and coupling reactions, in virtue of the light-absorption of photoreactive materials such as the immobilized photoinitiator and spread photoinitiator solution on the surfaces exposed to UV light and the sheltering of densely arrayed immovable particles from light. Varying the monomers or macromolecules applied in photografting polymerization or coupling reaction, and choosing diverse polymeric particles of various size, bicolor and amphiphilic Janus particles could be successfully achieved. Observations by fluorescence microscope, scanning electron microscope ,and transmission electron microscope confirmed the asymmetrical morphology of the resultant Janus particles.

Electronic properties of epitaxial silicene: a LT-STM/STS study

NASA Astrophysics Data System (ADS)

Fleurence, Antoine; Lee, Chi-Cheng; Ozaki, Taisuke; Yamada-Takamura, Yukiko; Yoshida, Yasuo; Hasegawa, Yukio

2013-03-01

The astonishing properties of silicene, the Si-counterpart of graphene, together with pioneering experimental observations, triggered in the very recent years, an exponentially increasing interest for this atom-thick material, both at fundamental level and for applications in high-speed electronic devices. We demonstrated, that the spontaneous segregation of silicon on (0001) surface of zirconium diboride (ZrB2) thin films epitaxied on Si(111) wafers gives rise to a wide-scale uniform two-dimensional silicene sheet. The silicene nature of the honeycomb structure imaged by scanning tunneling microscopy is evidenced by the observation of gap-opened π-electronic bands. The band gap opening is primarily due the specifically imprinted buckling. Here, we present the results of a low-temperature scanning tunneling spectroscopy investigation, which evidences the n-doped nature of silicene. The mapping of the local density of states, together with density functional theory give precious insights into the microscopic origin of the electronic bands of silicene. In particular, it shows the correlation between the degree of sp2 hybridization of different Si atoms in the internal structure and the character of the electronic bands.

Interaction of electrons with light metal hydrides in the transmission electron microscope.

PubMed

Wang, Yongming; Wakasugi, Takenobu; Isobe, Shigehito; Hashimoto, Naoyuki; Ohnuki, Somei

2014-12-01

Transmission electron microscope (TEM) observation of light metal hydrides is complicated by the instability of these materials under electron irradiation. In this study, the electron kinetic energy dependences of the interactions of incident electrons with lithium, sodium and magnesium hydrides, as well as the constituting element effect on the interactions, were theoretically discussed, and electron irradiation damage to these hydrides was examined using in situ TEM. The results indicate that high incident electron kinetic energy helps alleviate the irradiation damage resulting from inelastic or elastic scattering of the incident electrons in the TEM. Therefore, observations and characterizations of these materials would benefit from increased, instead decreased, TEM operating voltage. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Improvement to the scanning electron microscope image adaptive Canny optimization colorization by pseudo-mapping.

PubMed

Lo, T Y; Sim, K S; Tso, C P; Nia, M E

2014-01-01

An improvement to the previously proposed adaptive Canny optimization technique for scanning electron microscope image colorization is reported. The additional feature, called pseudo-mapping technique, is that the grayscale markings are temporarily mapped to a set of pre-defined pseudo-color map as a mean to instill color information for grayscale colors in chrominance channels. This allows the presence of grayscale markings to be identified; hence optimization colorization of grayscale colors is made possible. This additional feature enhances the flexibility of scanning electron microscope image colorization by providing wider range of possible color enhancement. Furthermore, the nature of this technique also allows users to adjust the luminance intensities of selected region from the original image within certain extent. © 2014 Wiley Periodicals, Inc.

[Effects of Gravity on Attachment of Tendon to Bone

NASA Technical Reports Server (NTRS)

Johnson, Roger B.

1997-01-01

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

Simulation of transmission electron microscope images of biological specimens.

PubMed

Rullgård, H; Ofverstedt, L-G; Masich, S; Daneholt, B; Oktem, O

2011-09-01

We present a new approach to simulate electron cryo-microscope images of biological specimens. The framework for simulation consists of two parts; the first is a phantom generator that generates a model of a specimen suitable for simulation, the second is a transmission electron microscope simulator. The phantom generator calculates the scattering potential of an atomic structure in aqueous buffer and allows the user to define the distribution of molecules in the simulated image. The simulator includes a well defined electron-specimen interaction model based on the scalar Schrödinger equation, the contrast transfer function for optics, and a noise model that includes shot noise as well as detector noise including detector blurring. To enable optimal performance, the simulation framework also includes a calibration protocol for setting simulation parameters. To test the accuracy of the new framework for simulation, we compare simulated images to experimental images recorded of the Tobacco Mosaic Virus (TMV) in vitreous ice. The simulated and experimental images show good agreement with respect to contrast variations depending on dose and defocus. Furthermore, random fluctuations present in experimental and simulated images exhibit similar statistical properties. The simulator has been designed to provide a platform for development of new instrumentation and image processing procedures in single particle electron microscopy, two-dimensional crystallography and electron tomography with well documented protocols and an open source code into which new improvements and extensions are easily incorporated. © 2011 The Authors Journal of Microscopy © 2011 Royal Microscopical Society.

Revealing the 1 nm/s extensibility of nanoscale amorphous carbon in a scanning electron microscope.

PubMed

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. © Wiley Periodicals, Inc.

Low-voltage electron microscopy of polymer and organic molecular thin films.

PubMed

Drummy, Lawrence F; Yang, Junyan; Martin, David C

2004-06-01

We have demonstrated the capabilities of a novel low-voltage electron microscope (LVEM) for imaging polymer and organic molecular thin films. The LVEM can operate in transmission electron microscopy, scanning transmission electron microscopy, scanning electron microscopy, and electron diffraction modes. The microscope operates at a nominal accelerating voltage of 5 kV and fits on a tabletop. A detailed discussion of the electron-sample interaction processes is presented, and the mean free path for total electron scattering was calculated to be 15 nm for organic samples at 5 kV. The total end point dose for the destruction of crystallinity at 5 kV was estimated at 5 x 10(-4) and 3.5 x 10(-2) C/cm2 for polyethylene and pentacene, respectively. These values are significantly lower than those measured at voltages greater than 100 kV. A defocus series of colloidal gold particles allowed us to estimate the experimental contrast transfer function of the microscope. Images taken of several organic materials have shown high contrast for low atomic number elements and a resolution of 2.5 nm. The materials studied here include thin films of the organic semiconductor pentacene, triblock copolymer films, single-molecule dendrimers, electrospun polymer fibers and gold nanoparticles. Copyright 2004 Elsevier B.V.

[THE CHARACTERISTICS OF MORPHOLOGY OF BIOFILM OF PERIODONTIUM UNDER INFLAMMATORY DISEASES OF GUMS (CHRONIC CATARRHAL GINGIVITIS, CHRONIC PERIODONTITIS, CANDIDA-ASSOCIATED PERIODONTITIS) ACCORDING RESULTS OF ELECTRONIC MICROSCOPY].

PubMed

Ippolitov, E V; Didenko, L V; Tzarev, V N

2015-12-01

The study was carried out to analyze morphology of biofilm of periodontium and to develop electronic microscopic criteria of differentiated diagnostic of inflammatory diseases of gums. The scanning electronic microscopy was applied to analyze samples of bioflm of periodont from 70 patients. Including ten patients with every nosologic form of groups with chronic catarrhal periodontitis. of light, mean and severe degree, chronic catarrhal gingivitis, Candida-associated paroperiodontitis and 20 healthy persons with intact periodontium. The analysis was implemented using dual-beam scanning electronic microscope Quanta 200 3D (FEI company, USA) and walk-through electronic micJEM 100B (JEOL, Japan). To detect marker DNA of periodont pathogenic bacteria in analyzed samples the kit of reagentsfor polymerase chain reaction "MultiDent-5" ("GenLab", Russia). The scanning electronic microscopy in combination with transmission electronic microscopy and polymerase chain reaction permits analyzing structure, composition and degree of development of biofilm of periodontium and to apply differentiated diagnostic of different nosologic forms of inflammatory diseases of periodontium, including light form of chronic periodontitis and gingivitis. The electronic microscopical indications of diseases ofperiodontium of inflammatory character are established: catarrhal gingivitis, (coccal morphological alternate), chronic periodontitis (bacillary morphological alternate), Candida-associated periodontitis (Candida morphological alternate of biofilm ofperiodontium).

Acquisition parameters optimization of a transmission electron forward scatter diffraction system in a cold-field emission scanning electron microscope for nanomaterials characterization.

PubMed

Brodusch, Nicolas; Demers, Hendrix; Trudeau, Michel; Gauvin, Raynald

2013-01-01

Transmission electron forward scatter diffraction (t-EFSD) is a new technique providing crystallographic information with high resolution on thin specimens by using a conventional electron backscatter diffraction (EBSD) system in a scanning electron microscope. In this study, the impact of tilt angle, working distance, and detector distance on the Kikuchi pattern quality were investigated in a cold-field emission scanning electron microscope (CFE-SEM). We demonstrated that t-EFSD is applicable for tilt angles ranging from -20° to -40°. Working distance (WD) should be optimized for each material by choosing the WD for which the EBSD camera screen illumination is the highest, as the number of detected electrons on the screen is directly dependent on the scattering angle. To take advantage of the best performances of the CFE-SEM, the EBSD camera should be close to the sample and oriented towards the bottom to increase forward scattered electron collection efficiency. However, specimen chamber cluttering and beam/mechanical drift are important limitations in the CFE-SEM used in this work. Finally, the importance of t-EFSD in materials science characterization was illustrated through three examples of phase identification and orientation mapping. © Wiley Periodicals, Inc.

Direction-division multiplexed holographic free-electron-driven light sources

NASA Astrophysics Data System (ADS)

Clarke, Brendan P.; MacDonald, Kevin F.; Zheludev, Nikolay I.

2018-01-01

We report on a free-electron-driven light source with a controllable direction of emission. The source comprises a microscopic array of plasmonic surface-relief holographic domains, each tailored to direct electron-induced light emission at a selected wavelength into a collimated beam in a prescribed direction. The direction-division multiplexed source is tested by driving it with the 30 kV electron beam of a scanning electron microscope: light emission, at a wavelength of 800 nm in the present case, is switched among different output angles by micron-scale repositioning of the electron injection point among domains. Such sources, with directional switching/tuning possible at picosecond timescales, may be applied to field-emission and surface-conduction electron-emission display technologies, optical multiplexing, and charged-particle-beam position metrology.

Development of a high brightness ultrafast Transmission Electron Microscope based on a laser-driven cold field emission source.

PubMed

Houdellier, F; Caruso, G M; Weber, S; Kociak, M; Arbouet, A

2018-03-01

We report on the development of an ultrafast Transmission Electron Microscope based on a cold field emission source which can operate in either DC or ultrafast mode. Electron emission from a tungsten nanotip is triggered by femtosecond laser pulses which are tightly focused by optical components integrated inside a cold field emission source close to the cathode. The properties of the electron probe (brightness, angular current density, stability) are quantitatively determined. The measured brightness is the largest reported so far for UTEMs. Examples of imaging, diffraction and spectroscopy using ultrashort electron pulses are given. Finally, the potential of this instrument is illustrated by performing electron holography in the off-axis configuration using ultrashort electron pulses. Copyright © 2017 Elsevier B.V. All rights reserved.

Solid-state nanopores of controlled geometry fabricated in a transmission electron microscope

NASA Astrophysics Data System (ADS)

Qian, Hui; Egerton, Ray F.

2017-11-01

Energy-filtered transmission electron microscopy and electron tomography were applied to in situ studies of the formation, shape, and diameter of nanopores formed in a silicon nitride membrane in a transmission electron microscope. The nanopore geometry was observed in three dimensions by electron tomography. Drilling conditions, such as probe current, beam convergence angle, and probe position, affect the formation rate and the geometry of the pores. With a beam convergence semi-angle of α = 22 mrad, a conical shaped nanopore is formed but at α = 45 mrad, double-cone (hourglass-shaped) nanopores were produced. Nanopores with an effective diameter between 10 nm and 1.8 nm were fabricated by controlling the drilling time.

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

PubMed

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

2016-08-01

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

Lack of detection of a putative retrovirus associated with haemic neoplasia in the soft shell clam Mya arenaria.

PubMed

AboElkhair, M; Iwamoto, T; Clark, K F; McKenna, P; Siah, A; Greenwood, S J; Berthe, F C J; Casey, J W; Cepica, A

2012-01-01

Haemic neoplasia (HN) is a leukemia-like disease that affects at least 20 species of marine bivalves including soft shell clam, Mya arenaria. Since the disease was discovered in 1969, the etiology remains unknown. A retroviral etiology has been suggested based on the detection of reverse transcriptase activity and electron microscopic observation of retroviral-like particles using negative staining. To date, however no virus isolate and no retroviral sequence from HN has been obtained. Moreover, transmission of the disease by cell-free filtrate from affected clams has not been reproduced. In the current study, we reinvestigated the association of HN with a putative retrovirus. Sucrose gradient centrifugation followed by assessment of reverse transcriptase activity, electrophoretic analysis of protein and RNA, and electron microscopic examinations of fractions corresponding to retroviral density were employed. Detection of retroviral pol sequences using degenerate RT-PCR approaches was also attempted. Our results showed visible bands at the expected density of retrovirus in HN-positive and HN-negative clam tissues and both with reverse transcriptase activity. Electron microscopy, RNA analysis, protein analysis, and PCR systems targeting the pol gene of retroviruses did not however provide clear evidence supporting presence of a retrovirus. We point out that the retrovirus etiology of HN of Mya arenaria proposed some 25 years ago should be reconsidered in the absence of a virus isolate or virus sequences. Copyright © 2011 Elsevier Inc. All rights reserved.

Micro-buffy coats of whole blood: a method for the electron microscopic study of mononuclear cells.

PubMed

Nunes, J F; Soares, J O; Alves de Matos, A P

1979-09-01

A method for the electron microscopic study of human peripheral lymphocytes by which very small buffy coats are obtained through centrifugation of heparinized whole blood in glass or plastic microhematocrit tubes is presented. This method is time saving and efficient, yielding well preserved material and a comparatively large number of mononuclear cells (mainly lymphocytes) in each thin section.

Practical application of HgI2 detectors to a space-flight scanning electron microscope

NASA Technical Reports Server (NTRS)

Bradley, J. G.; Conley, J. M.; Albee, A. L.; Iwanczyk, J. S.; Dabrowski, A. J.

1989-01-01

Mercuric iodide X-ray detectors have been undergoing tests in a prototype scanning electron microscope system being developed for unmanned space flight. The detector program addresses the issues of geometric configuration in the SEM, compact packaging that includes separate thermoelectric coolers for the detector and FET, X-ray transparent hermetic encapsulation and electrical contacts, and a clean vacuum environment.

Effect of process parameters on microstructure and mechanical properties of friction stir welded joints: A review

NASA Astrophysics Data System (ADS)

Wanare, S. P.; Kalyankar, V. D.

2018-04-01

Friction stir welding is emerging as a promising technique for joining of lighter metal alloys due to its several advantages over conventional fusion welding processes such as low thermal distortion, good mechanical properties, fine weld joint microstructure, etc. This review article mainly focuses on analysis of microstructure and mechanical properties of friction stir welded joints. Various microstructure characterization techniques used by previous researchers such as optical microscopes, x-ray diffraction, electron probe microscope, transmission electron microscope, scanning electron microscopes with electron back scattered diffraction, electron dispersive microscopy, etc. are thoroughly overviewed and their results are discussed. The effects of friction stir welding process parameters such as tool rotational speed, welding speed, tool plunge depth, axial force, tool shoulder diameter to tool pin diameter ratio, tool geometry etc. on microstructure and mechanical properties of welded joints are studied and critical observations are noted down. The microstructure examination carried out by previous researchers on various zones of welded joints such as weld zone, heat affected zone and base metal are studied and critical remarks have been presented. Mechanical performances of friction stir welded joints based on tensile test, micro-hardness test, etc. are discussed. This article includes exhaustive literature review of standard research articles which may become ready information for subsequent researchers to establish their line of action.

Automated in-chamber specimen coating for serial block-face electron microscopy.

PubMed

Titze, B; Denk, W

2013-05-01

When imaging insulating specimens in a scanning electron microscope, negative charge accumulates locally ('sample charging'). The resulting electric fields distort signal amplitude, focus and image geometry, which can be avoided by coating the specimen with a conductive film prior to introducing it into the microscope chamber. This, however, is incompatible with serial block-face electron microscopy (SBEM), where imaging and surface removal cycles (by diamond knife or focused ion beam) alternate, with the sample remaining in place. Here we show that coating the sample after each cutting cycle with a 1-2 nm metallic film, using an electron beam evaporator that is integrated into the microscope chamber, eliminates charging effects for both backscattered (BSE) and secondary electron (SE) imaging. The reduction in signal-to-noise ratio (SNR) caused by the film is smaller than that caused by the widely used low-vacuum method. Sample surfaces as large as 12 mm across were coated and imaged without charging effects at beam currents as high as 25 nA. The coatings also enabled the use of beam deceleration for non-conducting samples, leading to substantial SNR gains for BSE contrast. We modified and automated the evaporator to enable the acquisition of SBEM stacks, and demonstrated the acquisition of stacks of over 1000 successive cut/coat/image cycles and of stacks using beam deceleration or SE contrast. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

Visualization of Neutrophil Extracellular Traps and Fibrin Meshwork in Human Fibrinopurulent Inflammatory Lesions: III. Correlative Light and Electron Microscopic Study

PubMed Central

Onouchi, Takanori; Shiogama, Kazuya; Mizutani, Yasuyoshi; Takaki, Takashi; Tsutsumi, Yutaka

2016-01-01

Neutrophil extracellular traps (NETs) released from dead neutrophils at the site of inflammation represent webs of neutrophilic DNA stretches dotted with granule-derived antimicrobial proteins, including lactoferrin, and play important roles in innate immunity against microbial infection. We have shown the coexistence of NETs and fibrin meshwork in varied fibrinopurulent inflammatory lesions at both light and electron microscopic levels. In the present study, correlative light and electron microscopy (CLEM) employing confocal laser scanning microscopy and scanning electron microscopy was performed to bridge light and electron microscopic images of NETs and fibrin fibrils in formalin-fixed, paraffin-embedded, autopsied lung sections of legionnaire’s pneumonia. Lactoferrin immunoreactivity and 4'-6-diamidino-2-phenylindole (DAPI) reactivity were used as markers of NETs, and fibrin was probed by fibrinogen gamma chain. Of note is that NETs light microscopically represented as lactoferrin and DAPI-colocalized dots, 2.5 μm in diameter. CLEM gave super-resolution images of NETs and fibrin fibrils: “Dotted” NETs were ultrastructurally composed of fine filaments and masses of 58 nm-sized globular materials. A fibrin fibril consisted of clusters of smooth-surfaced filaments. NETs filaments (26 nm in diameter) were significantly thinner than fibrin filaments (295 nm in diameter). Of note is that CLEM was applicable to formalin-fixed, paraffin-embedded sections of autopsy material. PMID:27917008

Multi-Scale Investigation of the Formation and Breakdown of Passive Films on Carbon Steel Rebar in Concrete

NASA Astrophysics Data System (ADS)

Ghods, Pouria

The multi-scale investigation presented in this thesis was carried out to understand better the mechanisms of passivation and chloride-induced depassivation of carbon steel reinforcement in concrete. The study consisted of electrochemical experiments (electrochemical impedance spectroscopy, linear polarization resistance, free corrosion potential, anodic polarization), microscopic examinations (scanning electron microscopy, transmission electron microscopy, selected area diffraction, convergent beam electron diffraction), numerical modeling (finite element method), and spectroscopic studies (x-ray photoelectron, energy dispersed x-ray, electron energy loss). Electrochemical and microscopic studies showed that the composition of the pore solution and the surface conditions of the rebar affect the passivity and depassivation of carbon steel in concrete. It was demonstrated that crevices between mill scale and steel may become potential sites for depassivation and pit nucleation. The numerical investigation that was carried out to test this hypothesis confirmed that the ratio of chloride to hydroxide concentrations, Cl-/OH-, in crevices increased to levels higher than that of the bulk pore solution, making crevices more vulnerable to depassivation. Therefore, it was concluded that the variability associated with reported chloride thresholds might be attributed, at least in part, to the variability in mill scale properties resulting from the variability in manufacturing. The nano-scale microscopic and spectroscopic studies indicated the formation of 4-10 nm-thick passive oxide films on carbon steel in simulated concrete pore solutions, and these films consisted of two layers separated with an indistinct border. The inner layer was mainly composed of protective Fe2+-rich oxides that are in epitaxial relationship with the underlying steel surface; while the outer layer mostly consisted of (possibly porous) Fe3+-rich oxides, through which chlorides can penetrate. It was proposed that, in the presence of chlorides, Fe+2-rich oxides in the inner layer transform into Fe+3-rich oxides and potentially become un-protective. Although how this transformation occurs is still subject of future research, there are evidences showing that the process most likely leads to the formation of local anodic and cathodic sites on the steel surface.

Summary of in situ epitaxial nucleation and growth measurements. [for semiconducting single crystal PbSe films

NASA Technical Reports Server (NTRS)

Poppa, H.; Moorhead, R. D.; Heinemann, K.

1974-01-01

In situ nucleation and growth measurements of Ag and Au on single-crystal PbSe thin films were made using a transmission electron microscope. Properties studied were polymorphism, crystalline perfection, and the stoichiometric composition of the initial and the autoepitaxially thickened PbSe substrates. The quantitative nucleation and cluster growth measurements were limited to low-saturation conditions. The epitaxial orientations are discussed, and evidence is presented as to the stage of deposition at which the epitaxial order for Ag is introduced. Strong substrate/overgrowth interaction manifested itself by alloying and interdiffusion.

Isolation of a Diatom Frustule Fragment from the Lower Stratosphere (22-27Km)-EVIDENCE for a Cosmic Origin

NASA Astrophysics Data System (ADS)

Wainwright, Milton; Rose, Christopher E.; Baker, Alexander J.; Briston, J. K.; Wickramasinghe, N. Chandra

2013-03-01

Sampling of the stratosphere at heights between 22 and 27 km was carried out in the UK on 31st July 2013 using balloon-borne equipment carrying aseptically clean electron microscope stubs onto which aerosols were directly captured. The experiment revealed the presence of a diatom frustule captured from a height of >25km. On account of the very short residence time of particles of diatom size and mass at these heights, we argue for its incidence from space, with a probable origin in the watery environment of a comet.

Characterization-curing-property studies of HBRF 55A resin formulations

NASA Technical Reports Server (NTRS)

Pearce, E. M.; Mijovic, J.

1985-01-01

Characterization curing property investigations on HBRF 55A resin formulations are reported. The initial studies on as received cured samples cut from a full-size FWC are reviewed. Inadequacies of as-received and aged samples are pointed out and additional electron microscopic evidence is offered. Characterization of as-received ingredients of HBRF 55A formulation is described. Specifically, Epon 826, Epon 828, EpiRez 5022, RD-2 and various amines, including Tonox and Tonox 60.40, were characterized. Cure kinetics of various formulations are investigated. Changes in physical/thermal properties (viscosity, specific heat, thermal conductivity and density) during cure are described.

A pancreatic venular defect in the BB/Wor rat.

PubMed Central

Majno, G.; Joris, I.; Handler, E. S.; Desemone, J.; Mordes, J. P.; Rossini, A. A.

1987-01-01

BB rats develop spontaneous autoimmune diabetes mellitus characterized morphologically by insulitis, an inflammatory lymphocytic infiltration of the islets of Langerhans. To investigate the role of the vascular endothelium of the pancreas in this destructive process, the authors injected diabetes-prone (DP) and diabetes-resistant (DR) BB/Wor rats as well as other nondiabetic strains of rats with Monastral blue B, a colloidal pigment that identifies leaky microvasculature. They found evidence of a venular defect limited to the pancreas that is specific to the BB rat. Light- and electron-microscopic evidence suggests that this defect is due to a population of trapped (marginating) intravascular monocytes, which may be activated by the colloidal pigment and release vasoactive mediators. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:3618725

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

Chandrasekaran, S.; Liebig, W. V.; Mecklenberg, M.

Aerographite (AG) is a mechanically robust, lightweight synthetic cellular material, which consists of a 3D interconnected network of tubular carbon [1]. The presence of open channels in AG aids to infiltrate them with polymer matrices, thereby yielding an electrical conducting and lightweight composite. Aerographite produced with densities in the range of 7–15 mg/cm 3 was infiltrated with a low viscous epoxy resin by means of vacuum infiltration technique. Detailed morphological and structural investigations on synthesized AG and AG/epoxy composite were performed by scanning electron microscopic techniques. Our present study investigates the fracture and failure of AG/epoxy composites and its energymore » absorption capacity under compression. The composites displayed an extended plateau region when uni-axially compressed, which led to an increase in energy absorption of ~133% per unit volume for 1.5 wt% of AG, when compared to pure epoxy. Preliminary results on fracture toughness showed an enhancement of ~19% in K IC for AG/epoxy composites with 0.45 wt% of AG. Furthermore, our observations of fractured surfaces under scanning electron microscope gives evidence of pull-out of arms of AG tetrapod, interface and inter-graphite failure as the dominating mechanism for the toughness improvement in these composites. These observations were consistent with the results obtained from photoelasticity experiments on a thin film AG/epoxy model composite.« less

Toxicological effects and recovery of the corneal epithelium in Cyprinus carpio communis Linn. exposed to monocrotophos: an scanning electron microscope study.

PubMed

Uppal, Ravneet Kaur; Johal, Mohinder Singh; Sharma, Madan Lal

2015-05-01

This study was conducted based on the evidence of fish habitats in North India being affected by organophosphate pesticides draining from agricultural fields into bodies of water, especially during the rainy season. Various tissues of fish such as scales, gills ovaries, kidney, and liver have been studied from the toxicological point of view, but the toxicological effects of aquatic pollutants on fish cornea have not been investigated to date. We conducted comparative toxicological studies on the cornea of Cyprinus carpio communis using two sublethal (0.038 and 0.126 ppm) concentrations of monocrotophos pesticide for 30 days. Corneas from all the groups were evaluated by a scanning electron microscope. The fish exposed to the monocrotophos pesticide developed corneal necrosis due to the formation of crystalloid-like structures, thinning and shrinkage of microridges on the corneal epithelium. After 30 days, fish from the monocrotophos-treated tank were transferred to normal environmental conditions. After 60 days under natural condition, epithelial cells did not fully recover. In conclusion, exposure to monocrotophos induces irreversible changes in the cornea of C. carpio communis. As fish and mammalian visual systems share many similarities, the reported finding may offer useful insights for further toxicological and ophthalmological studies in humans. © 2013 American College of Veterinary Ophthalmologists.

Disentangling specific versus generic doping mechanisms in oxide heterointerfaces

NASA Astrophysics Data System (ADS)

Gabel, J.; Zapf, M.; Scheiderer, P.; Schütz, P.; Dudy, L.; Stübinger, M.; Schlueter, C.; Lee, T.-L.; Sing, M.; Claessen, R.

2017-05-01

More than a decade after the discovery of the two-dimensional electron system (2DES) at the interface between the band insulators LaAlO3 (LAO) and SrTiO3 (STO) its microscopic origin is still under debate. Several explanations have been proposed, the main contenders being electron doping by oxygen vacancies and electronic reconstruction, i.e., the redistribution of electrons to the interface to minimize the electrostatic energy in the polar LAO film. However, no experiment thus far could provide unambiguous information on the microscopic origin of the interfacial charge carriers. Here we utilize a novel experimental approach combining photoelectron spectroscopy (PES) with highly brilliant synchrotron radiation and apply it to a set of samples with varying key parameters that are thought to be crucial for the emergence of interfacial conductivity. Based on microscopic insight into the electronic structure, we obtain results tipping the scales in favor of polar discontinuity as a generic, robust driving force for the 2DES formation. Likewise, other functionalities such as magnetism or superconductivity might be switched in all-oxide devices by polarity-driven charge transfer.

Fine structure of the dorsal lingual epithelium of the juvenile hawksbill turtle, Eretmochelys imbricata bissa.

PubMed

Iwasaki, S; Asami, T; Wanichanon, C

1996-04-01

Various species of turtles are adapted to different environments, such as freshwater, seawater, and terrestrial habitats. Comparisons of histological and ultrastructural features of the tongue of the juvenile Hawksbill turtle, Eretmochelys imbricata bissa, with those of freshwater turtles should reveal some aspects of the relationship between the structure of the lingual epithelium and the environment. The light microscope, scanning electron microscope and transmission electron microscope were used. Light microscopy revealed that the mucosal epithelium of the tongue was of the keratinized, stratified squamous type. Under the scanning electron microscope, no lingual papillae were visible on the dorsal surface of the tongue. Micropits and the thickening of cell margins were clearly seen on the surface of cells located on the outermost side. The transmission electron microscope revealed that the cells in the intermediate layer were gradually flattened from the basal side to the surface side, as were their nuclei. In the shallow intermediate layer, the cells were significantly flattened, and their nuclei were condensed or had disappeared. The cytoplasm contained keratohyalin granules, tonofibrils, free ribosomes, mitochondria, and rough endoplasmic reticulum. Numerous free ribosomes were attached to the surface of small keratohyalin granules. The cells of the keratinized layer were significantly flattened, and their nuclei had completely disappeared. Most of cytoplasm was filled with keratin fibers of high electron density. Keratin fibers of the shedding cells, which were located on the outermost side of the keratinized layer, appeared looser, and each fiber, which was somewhat thicker than the tonofibrils and tonofilaments, was clearly distinguishable. The lingual epithelium of the juvenile Hawksbill turtle differs significantly from that of the adult freshwater turtle, in spite of the similarity in gross morphology of the tongues of these species.

Terrestrial Clay under Microscope

NASA Image and Video Library

2008-09-30

A scanning electron microscope captured this image of terresterial soil containing a phyllosilicate mineral from Koua Bocca, Ivory Coast, West Africa. This soil shares some similarities with Martian soil scooped by NASA Phoenix Lander.

Characterization of quantum well structures using a photocathode electron microscope

NASA Technical Reports Server (NTRS)

Spencer, Michael G.; Scott, Craig J.

1989-01-01

Present day integrated circuits pose a challenge to conventional electronic and mechanical test methods. Feature sizes in the submicron and nanometric regime require radical approaches in order to facilitate electrical contact to circuits and devices being tested. In addition, microwave operating frequencies require careful attention to distributed effects when considering the electrical signal paths within and external to the device under test. An alternative testing approach which combines the best of electrical and optical time domain testing is presented, namely photocathode electron microscope quantitative voltage contrast (PEMQVC).

The free-electron laser - Maxwell's equations driven by single-particle currents

NASA Technical Reports Server (NTRS)

Colson, W. B.; Ride, S. K.

1980-01-01

It is shown that if single particle currents are coupled to Maxwell's equations, the resulting set of self-consistent nonlinear equations describes the evolution of the electron beam and the amplitude and phase of the free-electron-laser field. The formulation is based on the slowly varying amplitude and phase approximation, and the distinction between microscopic and macroscopic scales, which distinguishes the microscopic bunching from the macroscopic pulse propagation. The capabilities of this new theoretical approach become apparent when its predictions for the ultrashort pulse free-electron laser are compared to experimental data; the optical pulse evolution, determined simply and accurately, agrees well with observations.

Analysis with electron microscope of multielement samples using pure element standards

DOEpatents

King, W.E.

1986-01-06

This disclosure describes a method and modified analytical electron microscope for determining the concentration of elements in a multielement sample by exposing samples with differing thicknesses for each element to a beam of electrons. Simultaneously the electron dosage and x-ray intensities are measured for each sample of element to determine a ''K/sub AB/'' value to be used in the equation (I/sub A/I/sub B/) = K/sub AB/ (C/sub A//C/sub B/), where I is intensity and C is concentration for elements A and B. The multielement sample is exposed to determine the concentrations of the elements in the sample.

Microstructural study of the nickel-base alloy WAZ-20 using qualitative and quantitative electron optical techniques

NASA Technical Reports Server (NTRS)

Young, S. G.

1973-01-01

The NASA nickel-base alloy WAZ-20 was analyzed by advanced metallographic techniques to qualitatively and quantitatively characterize its phases and stability. The as-cast alloy contained primary gamma-prime, a coarse gamma-gamma prime eutectic, a gamma-fine gamma prime matrix, and MC carbides. A specimen aged at 870 C for 1000 hours contained these same constituents and a few widely scattered high W particles. No detrimental phases (such as sigma or mu) were observed. Scanning electron microscope, light metallography, and replica electron microscope methods are compared. The value of quantitative electron microprobe techniques such as spot and area analysis is demonstrated.

Observation of a brine layer on an ice surface with an environmental scanning electron microscope at higher pressures and temperatures.

PubMed

Krausko, Ján; Runštuk, Jiří; Neděla, Vilém; Klán, Petr; Heger, Dominik

2014-05-20

Observation of a uranyl-salt brine layer on an ice surface using backscattered electron detection and ice surface morphology using secondary-electron detection under equilibrium conditions was facilitated using an environmental scanning electron microscope (ESEM) at temperatures above 250 K and pressures of hundreds of Pa. The micrographs of a brine layer over ice grains prepared by either slow or shock freezing provided a complementary picture of the contaminated ice grain boundaries. Fluorescence spectroscopy of the uranyl ions in the brine layer confirmed that the species exists predominately in the solvated state under experimental conditions of ESEM.

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

PubMed

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

2017-09-01

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

Highly dispersible diamond nanoparticles for pretreatment of diamond films on Si substrate

NASA Astrophysics Data System (ADS)

Zhao, Shenjie; Huang, Jian; Zhou, Xinyu; Ren, Bing; Tang, Ke; Xi, Yifan; Wang, Lin; Wang, Linjun; Lu, Yicheng

2018-03-01

High quality diamond film on Si substrate was synthesized by coating diamond nanoparticles prepared by polyglycerol grafting (ND-PG) dispersion as pre-treatment method. Transmission electron microscope indicates that ND-PG is much more dispersible than untreated nanoparticles in organic solvents. The surface morphology was characterized by scanning electron microscope while atomic force microscope was conducted to measure the surface roughness. Microstructure properties were carried out by Raman spectroscopy and X-ray diffraction. The results revealed an increase in nucleation density, an acceleration of growth rate and an improvement of film crystalline quality by using spin-coating ND-PG pretreatment.

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

NASA Astrophysics Data System (ADS)

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

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

Electron microscopy study of the iron meteorite Santa Catharina

NASA Technical Reports Server (NTRS)

Zhang, J.; Williams, D. B.; Goldstein, J. I.; Clarke, R. S., Jr.

1990-01-01

A characterization of the microstructural features of Santa Catharina (SC) from the millimeter to submicron scale is presented. The same specimen was examined using an optical microscope, a scanning electron microscope, an electron probe microanalyzer, and an analytical electron microscope. Findings include the fact that SC metal nodules may have different bulk Ni values, leading to different microstructures upon cooling; that SC USNM 6293 is the less corroded sample, as tetrataenite exists as less than 10 nm ordered domains throughout the entire fcc matrix (it is noted that this structure is the same as that of the Twin City meteorite and identical to clear taenite II in the retained taenite regions of the octahedrites); that SC USNM 3043 has a more complicated microstructure due to corrosion; and that the low Ni phase of the cloudy zone was selectively corroded in some areas and formed the dark regions, indicating that the SC meteorite corrosion process was electrochemical in nature and may involve Cl-containing akaganeite.

Acquisition of a High Resolution Field Emission Scanning Electron Microscope for the Analysis of Returned Samples

NASA Technical Reports Server (NTRS)

Nittler, Larry R.

2003-01-01

This grant furnished funds to purchase a state-of-the-art scanning electron microscope (SEM) to support our analytical facilities for extraterrestrial samples. After evaluating several instruments, we purchased a JEOL 6500F thermal field emission SEM with the following analytical accessories: EDAX energy-dispersive x-ray analysis system with fully automated control of instrument and sample stage; EDAX LEXS wavelength-dispersive x-ray spectrometer for high sensitivity light-element analysis; EDAX/TSL electron backscatter diffraction (EBSD) system with software for phase identification and crystal orientation mapping; Robinson backscatter electron detector; and an in situ micro-manipulator (Kleindiek). The total price was $550,000 (with $150,000 of the purchase supported by Carnegie institution matching funds). The microscope was delivered in October 2002, and most of the analytical accessories were installed by January 2003. With the exception of the wavelength spectrometer (which has been undergoing design changes) everything is working well and the SEM is in routine use in our laboratory.

Progress on PEEM3 -- An Aberration Corrected X-Ray Photoemission Electron Microscope at the ALS

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

MacDowell, A. A.; Feng, J.; DeMello, A.

2007-01-19

A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed and built at the Advanced Light Source (ALS). An electron mirror combined with a much-simplified magnetic dipole separator is to be used to provide simultaneous correction of spherical and chromatic aberrations. It is installed on an elliptically polarized undulator (EPU) beamline, and will be operated with very high spatial resolution and high flux to study the composition, structure, electric and magnetic properties of complex materials. The instrument has been designed and is described. The instrumental hardware is being deployed in 2 phases. The first phase is the deployment ofmore » a standard PEEM type microscope consisting of the standard linear array of electrostatic electron lenses. The second phase will be the installation of the aberration corrected upgrade to improve resolution and throughput. This paper describes progress as the instrument enters the commissioning part of the first phase.« less

Progress on PEEM3 - An Aberration Corrected X-Ray PhotoemissionElectron Microscope at the ALS

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

MacDowell, Alastair A.; Feng, J.; DeMello, A.

2006-05-20

A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed and built at the Advanced Light Source (ALS). An electron mirror combined with a much-simplified magnetic dipole separator is to be used to provide simultaneous correction of spherical and chromatic aberrations. It is installed on an elliptically polarized undulator (EPU) beamline, and will be operated with very high spatial resolution and high flux to study the composition, structure, electric and magnetic properties of complex materials. The instrument has been designed and is described. The instrumental hardware is being deployed in 2 phases. The first phase is the deployment ofmore » a standard PEEM type microscope consisting of the standard linear array of electrostatic electron lenses. The second phase will be the installation of the aberration corrected upgrade to improve resolution and throughput. This paper describes progress as the instrument enters the commissioning part of the first phase.« less

Intracellular localisation of dengue-2 RNA in mosquito cell culture using electron microscopic in situ hybridisation.

PubMed

Grief, C; Galler, R; Côrtes, L M; Barth, O M

1997-01-01

Non-isotopic in situ hybridisation was used at the electron microscope level to determine the localisation of viral RNA in dengue-2 infected mosquito cells at 14, 24, 48 and 72 h post-infection. In situ hybridisation was carried out on sections of dengue-2 infected mosquito cells using a digoxigenin-labelled DNA probe to the envelope protein gene sequence of the virus. Viral RNA was consistently localised over the rough endoplasmic reticulum and the virus-induced smooth membrane structures which form within the endoplasmic reticulum. During the later stages of infection electron-dense areas were observed to develop in close proximity to the smooth membrane structures. Electron microscopic in situ hybridisation showed that these denser areas contained both viral RNA and virus particles. Our results show that in dengue-2 infected mosquito cells the smooth membrane structures are an important site for the concentration of dengue viral RNA and its possible subsequent encapsidation into virus particles.

Diagnosis of electrocution: The application of scanning electron microscope and energy-dispersive X-ray spectroscopy in five cases.

PubMed

Visonà, S D; Chen, Y; Bernardi, P; Andrello, L; Osculati, A

2018-03-01

Deaths from electricity, generally, do not have specific findings at the autopsy. The diagnosis is commonly based on the circumstances of the death and the morphologic findings, above all the current mark. Yet, the skin injury due to an electrocution and other kinds of thermal injuries often cannot be differentiated with certainty. Therefore, there is a great interest in finding specific markers of electrocution. The search for the metallization of the skin through Scanning Electron Microscope equipped with Energy Dispersive X-Ray Spectroscopy (EDS) probe is of special importance in order to achieve a definite diagnosis in case of suspected electrocution. We selected five cases in which the electrocution was extremely likely considering the circumstances of the death. In each case a forensic autopsy was performed. Then, the skin specimens were stained with Hematoxylin Eosin and Perls. On the other hand, the skin lesions were examined with a scanning electron microscope equipped with EDS probe in order to evaluate the morphological ultrastructural features and the presence of deposits on the surface of the skin. The typical skin injury of the electrocution (current mark) were macroscopically detected in all of the cases. The microscopic examination of the skin lesions revealed the typical spherical vacuoles in the horny layer and, in the epidermis, the elongation of the cell nuclei as well as necrosis. Perls staining was negative in 4 out 6 cases. Ultrastructural morphology revealed the evident vacuolization of the horny layer, elongation of epidermic cells, coagulation of the elastic fibers. In the specimens collected from the site of contact with the conductor of case 1 and 2, the presence of the Kα peaks of iron was detected. In the corresponding specimens taken from cases 2, 4, 5 the microanalysis showed the Kα peaks of titanium. In case 3, titanium and carbon were found. In the suspicion of electrocution, the integrated use of different tools is recommended, including macroscopic observation, H&E staining, iron-specific staining, scanning electron microscopy and EDS microanalysis. Only the careful interpretation of the results provided by all these methods can allow the pathologist to correctly identify the cause of the death. Particularly, the present study suggests that the microanalysis (SEM-EDS) represents a very useful tool for the diagnosis of electrocution, allowing the detection and the identification of the metals embedded in the skin and their evaluation in the context of the ultrastructural morphology. Copyright © 2018. Published by Elsevier B.V.

Thermal conductivity and dielectric functions of alkali chloride XCl (X = Li, Na, K and Rb): a first-principles study

NASA Astrophysics Data System (ADS)

Xu, M.; Yang, J. Y.; Liu, L. H.

2016-07-01

The macroscopic physical properties of solids are fundamentally determined by the interactions among microscopic electrons, phonons and photons. In this work, the thermal conductivity and infrared-visible-ultraviolet dielectric functions of alkali chlorides and their temperature dependence are fully investigated at the atomic level, seeking to unveil the microscopic quantum interactions beneath the macroscopic properties. The microscopic phonon-phonon interaction dominates the thermal conductivity which can be investigated by the anharmonic lattice dynamics in combination with Peierls-Boltzmann transport equation. The photon-phonon and electron-photon interaction intrinsically induce the infrared and visible-ultraviolet dielectric functions, respectively, and such microscopic processes can be simulated by first-principles molecular dynamics without empirical parameters. The temperature influence on dielectric functions can be effectively included by choosing the thermally equilibrated configurations as the basic input to calculate the total dipole moment and electronic band structure. The overall agreement between first-principles simulations and literature experiments enables us to interpret the macroscopic thermal conductivity and dielectric functions of solids in a comprehensive way.

Scanning electron microscope view of iron crystal

NASA Technical Reports Server (NTRS)

1972-01-01

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

Scanning electron microscope view of iron crystal

NASA Image and Video Library

1972-11-10

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

Direct evidence for a magnetic f-electron–mediated pairing mechanism of heavy-fermion superconductivity in CeCoIn5

PubMed Central

Van Dyke, John S.; Massee, Freek; Allan, Milan P.; Davis, J. C. Séamus; Petrovic, Cedomir; Morr, Dirk K.

2014-01-01

To identify the microscopic mechanism of heavy-fermion Cooper pairing is an unresolved challenge in quantum matter studies; it may also relate closely to finding the pairing mechanism of high-temperature superconductivity. Magnetically mediated Cooper pairing has long been the conjectured basis of heavy-fermion superconductivity but no direct verification of this hypothesis was achievable. Here, we use a novel approach based on precision measurements of the heavy-fermion band structure using quasiparticle interference imaging to reveal quantitatively the momentum space (k-space) structure of the f-electron magnetic interactions of CeCoIn5. Then, by solving the superconducting gap equations on the two heavy-fermion bands Ekα,β with these magnetic interactions as mediators of the Cooper pairing, we derive a series of quantitative predictions about the superconductive state. The agreement found between these diverse predictions and the measured characteristics of superconducting CeCoIn5 then provides direct evidence that the heavy-fermion Cooper pairing is indeed mediated by f-electron magnetism. PMID:25062692

Murphy's law-if anything can go wrong, it will: Problems in phage electron microscopy.

PubMed

Ackermann, Hans-W; Tiekotter, Kenneth L

2012-04-01

The quality of bacteriophage electron microscopy appears to be on a downward course since the 1980s. This coincides with the introduction of digital electron microscopes and a general lowering of standards, possibly due to the disappearance of several world-class electron microscopists The most important problem seems to be poor contrast. Positive staining is frequently not recognized as an undesirable artifact. Phage parts, bacterial debris, and aberrant or damaged phage particles may be misdiagnosed as bacterial viruses. Digital electron microscopes often seem to be operated without magnification control because this is difficult and inconvenient. In summary, most phage electron microscopy problems may be attributed to human failure. Journals are a last-ditch defense and have a heavy responsibility in selecting competent reviewers and rejecting, or not, unsatisfactory articles.

Considerable knock-on displacement of metal atoms under a low energy electron beam.

PubMed

Gu, Hengfei; Li, Geping; Liu, Chengze; Yuan, Fusen; Han, Fuzhou; Zhang, Lifeng; Wu, Songquan

2017-03-15

Under electron beam irradiation, knock-on atomic displacement is commonly thought to occur only when the incident electron energy is above the incident-energy threshold of the material in question. However, we report that when exposed to intense electrons at room temperature at a low incident energy of 30 keV, which is far below the theoretically predicted incident-energy threshold of zirconium, Zircaloy-4 (Zr-1.50Sn-0.25Fe-0.15Cr (wt.%)) surfaces can undergo considerable displacement damage. We demonstrate that electron beam irradiation of the bulk Zircaloy-4 surface resulted in a striking radiation effect that nanoscale precipitates within the surface layer gradually emerged and became clearly visible with increasing the irradiation time. Our transmission electron microscope (TEM) observations further reveal that electron beam irradiation of the thin-film Zircaly-4 surface caused the sputtering of surface α-Zr atoms, the nanoscale atomic restructuring in the α-Zr matrix, and the amorphization of precipitates. These results are the first direct evidences suggesting that displacement of metal atoms can be induced by a low incident electron energy below threshold. The presented way to irradiate may be extended to other materials aiming at producing appealing properties for applications in fields of nanotechnology, surface technology, and others.

Failure Analysis of Heavy-Ion-Irradiated Schottky Diodes

NASA Technical Reports Server (NTRS)

Casey, Megan C.; Lauenstein, Jean-Marie; Wilcox, Edward P.; Topper, Alyson D.; Campola, Michael J.; Label, Kenneth A.

2017-01-01

In this work, we use high- and low-magnitude optical microscope images, infrared camera images, and scanning electron microscope images to identify and describe the failure locations in heavy-ion-irradiated Schottky diodes.

Fabrication and In Situ Transmission Electron Microscope Characterization of Free-Standing Graphene Nanoribbon Devices.

PubMed

Wang, Qing; Kitaura, Ryo; Suzuki, Shoji; Miyauchi, Yuhei; Matsuda, Kazunari; Yamamoto, Yuta; Arai, Shigeo; Shinohara, Hisanori

2016-01-26

Edge-dependent electronic properties of graphene nanoribbons (GNRs) have attracted intense interests. To fully understand the electronic properties of GNRs, the combination of precise structural characterization and electronic property measurement is essential. For this purpose, two experimental techniques using free-standing GNR devices have been developed, which leads to the simultaneous characterization of electronic properties and structures of GNRs. Free-standing graphene has been sculpted by a focused electron beam in transmission electron microscope (TEM) and then purified and narrowed by Joule heating down to several nanometer width. Structure-dependent electronic properties are observed in TEM, and significant increase in sheet resistance and semiconducting behavior become more salient as the width of GNR decreases. The narrowest GNR width we obtained with the present method is about 1.6 nm with a large transport gap of 400 meV.

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

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

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

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

Characterization of the Micro-Abrasive Wear in Coatings of TaC-HfC/Au for Biomedical Implants

PubMed Central

Guzmán, Pablo; Yate, Luis; Sandoval, Mercy; Caballero, Jose

2017-01-01

The object of this work was the deposition of a Ta-Hf-C thin film with a gold interlayer on stainless steel, via the physical vapor deposition (PVD) technique, in order to evaluate the properties of different systems subjected to micro-abrasive wear phenomena generated by alumina particles in Ringer's solution. The surface characterization was performed using a scanning electron microscope (SEM) and atomic force microscope (AFM). The crystallographic phases exhibited for each coating were obtained by X-ray diffraction (XRD). As a consequence of modifying the composition of Ta-Hf there was evidence of an improvement in the micro-abrasive wear resistance and, for each system, the wear constants that confirm the enhancement of the surface were calculated. Likewise, these surfaces can be bioactive, generating an alternative to improve the biological fixation of the implants, therefore, the coatings of TaC-HfC/Au contribute in the development of the new generation of orthopedic implants. PMID:28773207

Understanding the interacted mechanism between carbonation and chloride aerosol attack in ordinary Portland cement concrete

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

Liu, Jun; Qiu, Qiwen; Chen, Xiaochi

An experimental study is carried out with the aim to understand the interacted mechanism between carbonation and chloride aerosol attack in ordinary Portland cement (OPC) concrete. Effects of carbonation on the chloride profile, the chloride binding capacity and the chloride diffusion coefficient are evaluated. Besides, effect of chloride aerosol attack on the carbonation rate is investigated. Concrete specimens with three water-to-cement ratios (0.38, 0.47 and 0.53) are fabricated in this work. Tested results demonstrate that carbonation remarkably affects the chloride profile, reduces the chloride binding capacity, and also accelerates the rate of chloride ion diffusion of concrete. Besides, the presencemore » of chloride aerosol can lead to lower the carbonation depth and increase the pH value of carbonated concrete. Microscopic properties such as morphology, porosity, and pore size distribution for the contaminated concretes are explored by scanning electron microscope and mercury intrusion porosimetry, which provide strong evidence to these research findings.« less

Interference evidence for Rashba-type spin splitting on a semimetallic WT e 2 surface

DOE PAGES

Li, Qing; Yan, Jiaqiang; Yang, Biao; ...

2016-09-13

Here, semimetallic tungsten ditelluride displays an extremely large nonsaturating magnetoresistance, which is thought to arise from the perfect n–p charge compensation with low carrier densities in WTe 2. We find a strong Rashba spin-orbit effect in density functional calculations due to the noncentrosymmetric structure. This lifts twofold spin degeneracy of the bands. A prominent umklapp interference pattern is observed by our scanning tunneling microscopic measurements at 4.2 K, which differs distinctly from the surface atomic structure demonstrated at 77 K. The energy dependence of umklapp interference shows a strong correspondence with densities of states integrated from ARPES measurement, manifesting amore » fact that the bands are spin-split on the opposite sides of Γ. Spectroscopic survey reveals the electron/hole asymmetry changes alternately with lateral locations along the b axis, providing a microscopic picture for double-carrier transport of semimetallic WTe 2. The conclusion is further supported by our ARPES results and Shubnikov–de Haas (SdH) oscillations measurements.« less

A brief discussion about image quality and SEM methods for quantitative fractography of polymer composites.

PubMed

Hein, L R O; Campos, K A; Caltabiano, P C R O; Kostov, K G

2013-01-01

The methodology for fracture analysis of polymeric composites with scanning electron microscopes (SEM) is still under discussion. Many authors prefer to use sputter coating with a conductive material instead of applying low-voltage (LV) or variable-pressure (VP) methods, which preserves the original surfaces. The present work examines the effects of sputter coating with 25 nm of gold on the topography of carbon-epoxy composites fracture surfaces, using an atomic force microscope. Also, the influence of SEM imaging parameters on fractal measurements is evaluated for the VP-SEM and LV-SEM methods. It was observed that topographic measurements were not significantly affected by the gold coating at tested scale. Moreover, changes on SEM setup leads to nonlinear outcome on texture parameters, such as fractal dimension and entropy values. For VP-SEM or LV-SEM, fractal dimension and entropy values did not present any evident relation with image quality parameters, but the resolution must be optimized with imaging setup, accompanied by charge neutralization. © Wiley Periodicals, Inc.

Experimental evaluation of environmental scanning electron microscopes at high chamber pressure.

PubMed

Fitzek, H; Schroettner, H; Wagner, J; Hofer, F; Rattenberger, J

2015-11-01

In environmental scanning electron microscopy (ESEM) high pressure applications have become increasingly important. Wet or biological samples can be investigated without time-consuming sample preparation and potential artefacts from this preparation can be neglected. Unfortunately, the signal-to-noise ratio strongly decreases with increasing chamber pressure. To evaluate the high pressure performance of ESEM and to compare different electron microscopes, information about spatial resolution and detector type is not enough. On the one hand, the scattering of the primary electron beam increases, which vanishes the contrast in images; and on the other hand, the secondary electrons (SE) signal amplification decreases. The stagnation gas thickness (effective distance the beam has to travel through the imaging gas) as well as the SE detection system depend on the microscope and for a complete and serious evaluation of an ESEM or low vacuum SEM it is necessary to specify these two parameters. A method is presented to determine the fraction of scattered and unscattered electrons and to calculate the stagnation gas thickness (θ). To evaluate the high pressure performance of the SE detection system, a method is presented that allows for an analysis of a single image and the calculation of the signal-to-noise ratio of this image. All investigations are performed on an FEI ESEM Quanta 600 (field emission gun) and an FEI ESEM Quanta 200 (thermionic gun). These methods and measurements should represent opportunities for evaluating the high pressure performance of an ESEM. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

[Electron microscopic study on the petechial hemorrhagic spots in patients with epidemic hemorrhage fever (EHF)].

PubMed

Wang, S Q; Feng, M; Yang, L

1994-12-01

EHF viral particles were found in the squamous epithelial cells and capillary endothelial cells of the petechial spots located at the mucous membrane of the soft palate in cases of early stage of severe type EHF by transmission electron microscopy. The viral particles are round or oval in shape, about 100 nm in diameter with a lipid bilayer envelope from which spikes are protruding. The virions matured by budding through the intracytoplasmic membranes into the smooth surfaced vesicles. The morphological characteristics of the virion coincided with the viral particles of Family Bunyaviridae. It was the first time to demonstrate that the squamous epithelial cells of the soft palate is one of the target cells in EHF virus infection and to describe the subcellular morphological evidence of the petechial spots at the soft palate by EM.

Atomic Defects and Doping of Monolayer NbSe2.

PubMed

Nguyen, Lan; Komsa, Hannu-Pekka; Khestanova, Ekaterina; Kashtiban, Reza J; Peters, Jonathan J P; Lawlor, Sean; Sanchez, Ana M; Sloan, Jeremy; Gorbachev, Roman V; Grigorieva, Irina V; Krasheninnikov, Arkady V; Haigh, Sarah J

2017-03-28

We have investigated the structure of atomic defects within monolayer NbSe 2 encapsulated in graphene by combining atomic resolution transmission electron microscope imaging, density functional theory (DFT) calculations, and strain mapping using geometric phase analysis. We demonstrate the presence of stable Nb and Se monovacancies in monolayer material and reveal that Se monovacancies are the most frequently observed defects, consistent with DFT calculations of their formation energy. We reveal that adventitious impurities of C, N, and O can substitute into the NbSe 2 lattice stabilizing Se divacancies. We further observe evidence of Pt substitution into both Se and Nb vacancy sites. This knowledge of the character and relative frequency of different atomic defects provides the potential to better understand and control the unusual electronic and magnetic properties of this exciting two-dimensional material.

Direct evidence of single quantum dot emission from GaN islands formed at threading dislocations using nanoscale cathodoluminescence: A source of single photons in the ultraviolet

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

Schmidt, Gordon, E-mail: Gordon.Schmidt@ovgu.de; Berger, Christoph; Veit, Peter

2015-06-22

Intense emission from GaN islands embedded in AlN resulting from GaN/AlN quantum well growth is directly resolved by performing cathodoluminescence spectroscopy in a scanning transmission electron microscope. Line widths down to 440 μeV are measured in a wavelength region between 220 and 310 nm confirming quantum dot like electronic properties in the islands. These quantum dot states can be structurally correlated to islands of slightly enlarged thicknesses of the GaN/AlN quantum well layer preferentially formed in vicinity to dislocations. The quantum dot states exhibit single photon emission in Hanbury Brown-Twiss experiments with a clear antibunching in the second order correlation function atmore » zero time delay.« less

Trinucleate uterine epithelial cells as evidence for White-tail Deer trophoblast binucleate cell migration and as markers of placental binucleate cell dynamics in a variety of wild ruminants.

PubMed

Wooding, F B Peter; Osborn, David; Killian, Gary J

2018-02-01

The unicellular trophoblast epithelium of all ruminants so far investigated contains 15-20% binucleate cells with numerous secretory granules. Electron microscope (EM) studies of the domesticated cow, ewe, goat and deer species have established that these BNC migrate out of the trophoblast epithelium to fuse with the apposed maternal uterine epithelial cells or derivative to form fetomaternal tissue throughout pregnancy. However there is one careful EM study of the trophoblast of a wild ruminant, the White-tail deer, which found the usual number of BNC but no evidence of any migration or fusion. Since there are up to 200 species of wild ruminants, it was important to establish whether there really are two possible scenarios for BNC function. This paper reports a light microscope (LM) immunocytochemical study of cell dynamics in ruminant placentas using 1-2 mμ deresinated sections. The results clearly demonstrate that the White-tail deer and all of the other 15 (see Table 1) randomly selected wild ruminants show the same BNC migration and fusion pattern. These results suggest that this remarkable cellular behaviour is fundamental to the ruminant evolutionary success. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrical potentials between stent-grafts made from different metals induce negligible corrosion.

PubMed

Kazimierczak, A; Podraza, W; Lenart, S; Wiernicki, I; Gutowski, P

2013-10-01

Evaluation of the risk of galvanic corrosion in various stent-grafts in current practice, when devices with unmatched alloy compositions are deployed together. Five nitinol (NT) and two steel (SS) stent-grafts produced by different companies were used in different combinations to create 21 samples (NT:NT, n = 10; NT:SS, n = 10; SS:SS, n = 1). Electric potential was measured between the metal couplings after immersion in 0.9% NaCl at a temperature of 37 °C. Subsequently, the same samples were incubated for 24 months in 0.9% NaCl at 37-39 °C under hermetic conditions and examined under a scanning electron microscope in order to search for any evidence of corrosion. Electric potentials between different metals alloys were found (means: NT:SS, 181 μV; NT:NT, 101 μV; SS:SS, 160 μV). The mean electrical potential between stainless steel and nitinol samples was significantly higher than between NT:NT couplings (p < .001). During the final scanning electron microscope examination, only one spot of pitting corrosion (>10 μm) on a nitinol surface was found (associated with previous mechanical damage) in an NT:SS sample after 24 months of incubation in vitro and no sign of mechanical failure of the wires was found. Direct contact between the stainless steel and the nitinol alloys does indeed create electrical potential but with a minimal risk of galvanic corrosion. No evidence was found for significant galvanic corrosion when two endovascular implants (stent-grafts) made from different metal composition were used in the same procedure. Copyright © 2013 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Electron microscopic evidence for the myosin head lever arm mechanism in hydrated myosin filaments using the gas environmental chamber

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

Minoda, Hiroki; CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012; Okabe, Tatsuhiro

2011-02-25

Research highlights: {yields} We succeeded in recording structural changes of hydrated myosin cross-bridges. {yields} We succeeded in position-marking the cross-bridges with site-directed antibodies. {yields} We recorded cross-bridge movement at different regions in individual cross-bridge. {yields} The movement was smallest at the cross-bridge-subfragment two boundary. {yields} The results provide evidence for the cross-bridge lever arm mechanism. -- Abstract: Muscle contraction results from an attachment-detachment cycle between the myosin heads extending from myosin filaments and the sites on actin filaments. The myosin head first attaches to actin together with the products of ATP hydrolysis, performs a power stroke associated with release ofmore » hydrolysis products, and detaches from actin upon binding with new ATP. The detached myosin head then hydrolyses ATP, and performs a recovery stroke to restore its initial position. The strokes have been suggested to result from rotation of the lever arm domain around the converter domain, while the catalytic domain remains rigid. To ascertain the validity of the lever arm hypothesis in muscle, we recorded ATP-induced movement at different regions within individual myosin heads in hydrated myosin filaments, using the gas environmental chamber attached to the electron microscope. The myosin head were position-marked with gold particles using three different site-directed antibodies. The amplitude of ATP-induced movement at the actin binding site in the catalytic domain was similar to that at the boundary between the catalytic and converter domains, but was definitely larger than that at the regulatory light chain in the lever arm domain. These results are consistent with the myosin head lever arm mechanism in muscle contraction if some assumptions are made.« less

Evidence for a Peierls phase-transition in a three-dimensional multiple charge-density waves solid

PubMed Central

Mansart, Barbara; Cottet, Mathieu J. G.; Penfold, Thomas J.; Dugdale, Stephen B.; Tediosi, Riccardo; Chergui, Majed; Carbone, Fabrizio

2012-01-01

The effect of dimensionality on materials properties has become strikingly evident with the recent discovery of graphene. Charge ordering phenomena can be induced in one dimension by periodic distortions of a material’s crystal structure, termed Peierls ordering transition. Charge-density waves can also be induced in solids by strong coulomb repulsion between carriers, and at the extreme limit, Wigner predicted that crystallization itself can be induced in an electrons gas in free space close to the absolute zero of temperature. Similar phenomena are observed also in higher dimensions, but the microscopic description of the corresponding phase transition is often controversial, and remains an open field of research for fundamental physics. Here, we photoinduce the melting of the charge ordering in a complex three-dimensional solid and monitor the consequent charge redistribution by probing the optical response over a broad spectral range with ultrashort laser pulses. Although the photoinduced electronic temperature far exceeds the critical value, the charge-density wave is preserved until the lattice is sufficiently distorted to induce the phase transition. Combining this result with ab initio electronic structure calculations, we identified the Peierls origin of multiple charge-density waves in a three-dimensional system for the first time. PMID:22451898

Experimental Evidence for Wigner’s Tunneling Time

NASA Astrophysics Data System (ADS)

Camus, N.; Yakaboylu, E.; Fechner, L.; Klaiber, M.; Laux, M.; Mi, Y.; Hatsagortsyan, K. Z.; Pfeifer, T.; Keitel, C. H.; Moshammer, R.

2018-04-01

Tunneling of a particle through a barrier is one of the counter-intuitive properties of quantum mechanical motion. Thanks to advances in the generation of strong laser fields, new opportunities to dynamically investigate this process have been developed. In the so-called attoclock measurements the electron’s properties after tunneling are mapped on its emission direction. We investigate the tunneling dynamics and achieve a high sensitivity thanks to two refinements of the attoclock principle. Using near-IR wavelength we place firmly the ionization process in the tunneling regime. Furthermore, we compare the electron momentum distributions of two atomic species of slightly different atomic potentials (argon and krypton) being ionized under absolutely identical conditions. Experimentally, using a reaction microscope, we succeed in measuring the 3D electron momentum distributions for both targets simultaneously. Theoretically, the time resolved description of tunneling in strong-field ionization is studied using the leading quantum-mechanical Wigner treatment. A detailed analysis of the most probable photoelectron emission for Ar and Kr allows testing the theoretical models and a sensitive check of the electron initial conditions at the tunnel exit. The agreement between experiment and theory provides a clear evidence for a non-zero tunneling time delay and a non-vanishing longitudinal momentum at this point.

Vise holds specimens for microscope

NASA Technical Reports Server (NTRS)

Greule, W. N.

1980-01-01

Convenient, miniature, spring-loaded clamp holds specimens for scanning electron microscope. Clamp is made out of nesting sections of studded angle-aluminum. Specimens are easier to mount and dismount with vise than with conductive adhesive or paint.

Mars Life? - Microscopic Tubular Structures

NASA Image and Video Library

1996-08-09

This electron microscope image shows tubular structures of likely Martian origin. These structures are very similar in size and shape to extremely tiny microfossils found in some Earth rocks. http://photojournal.jpl.nasa.gov/catalog/PIA00287

Collection of trace evidence of explosive residues from the skin in a death due to a disguised letter bomb. The synergy between confocal laser scanning microscope and inductively coupled plasma atomic emission spectrometer analyses.

PubMed

Turillazzi, Emanuela; Monaci, Fabrizio; Neri, Margherita; Pomara, Cristoforo; Riezzo, Irene; Baroni, Davide; Fineschi, Vittorio

2010-04-15

In most deaths caused by explosive, the victim's body becomes a depot for fragments of explosive materials, so contributing to the collection of trace evidence which may provide clues about the specific type of device used with explosion. Improvised explosive devices are used which contain "homemade" explosives rather than high explosives because of the relative ease with which such components can be procured. Many methods such as chromatography-mass spectrometry, scanning electron microscopy, stereomicroscopy, capillary electrophoresis are available for use in the identification of explosive residues on objects and bomb fragments. Identification and reconstruction of the distribution of explosive residues on the decedent's body may give additional hints in assessing the position of the victim in relation to the device. Traditionally these residues are retrieved by swabbing the body and clothing during the early phase, at autopsy. Gas chromatography-mass spectrometry and other analytical methods may be used to analyze the material swabbed from the victim body. The histological examination of explosive residues on skin samples collected during the autopsy may reveal significant details. The information about type, quantity and particularly about anatomical distribution of explosive residues obtained utilizing confocal laser scanning microscope (CLSM) together with inductively coupled plasma atomic emission spectrometer (ICP-AES), may provide very significant evidence in the clarification and reconstruction of the explosive-related events. Copyright 2009 Elsevier Ireland Ltd. All rights reserved.

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

PubMed Central

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

2016-01-01

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

Copper silicide/silicon nanowire heterostructures: in situ TEM observation of growth behaviors and electron transport properties.

PubMed

Chiu, Chung-Hua; Huang, Chun-Wei; Chen, Jui-Yuan; Huang, Yu-Ting; Hu, Jung-Chih; Chen, Lien-Tai; Hsin, Cheng-Lun; Wu, Wen-Wei

2013-06-07

Copper silicide has been studied in the applications of electronic devices and catalysts. In this study, Cu3Si/Si nanowire heterostructures were fabricated through solid state reaction in an in situ transmission electron microscope (TEM). The dynamic diffusion of the copper atoms in the growth process and the formation mechanism are characterized. We found that two dimensional stacking faults (SF) may retard the growth of Cu3Si. Due to the evidence of the block of edge-nucleation (heterogeneous) by the surface oxide, center-nucleation (homogeneous) is suggested to dominate the silicidation. Furthermore, the electrical transport properties of various silicon channel length with Cu3Si/Si heterostructure interfaces and metallic Cu3Si NWs have been investigated. The observations not only provided an alternative pathway to explore the formation mechanisms and interface properties of Cu3Si/Si, but also suggested the potential application of Cu3Si at nanoscale for future processing in nanotechnology.

Microscopic studies of the fate of charges in organic semiconductors: Scanning Kelvin probe measurements of charge trapping, transport, and electric fields in p- and n-type devices

NASA Astrophysics Data System (ADS)

Smieska, Louisa Marion

Organic semiconductors could have wide-ranging applications in lightweight, efficient electronic circuits. However, several fundamental questions regarding organic electronic device behavior have not yet been fully addressed, including the nature of chemical charge traps, and robust models for injection and transport. Many studies focus on engineering devices through bulk transport measurements, but it is not always possible to infer the microscopic behavior leading to the observed measurements. In this thesis, we present scanning-probe microscope studies of organic semiconductor devices in an effort to connect local properties with local device behavior. First, we study the chemistry of charge trapping in pentacene transistors. Working devices are doped with known pentacene impurities and the extent of charge trap formation is mapped across the transistor channel. Trap-clearing spectroscopy is employed to measure an excitation of the pentacene charge trap species, enabling identification of the degradationrelated chemical trap in pentacene. Second, we examine transport and trapping in peryelene diimide (PDI) transistors. Local mobilities are extracted from surface potential profiles across a transistor channel, and charge injection kinetics are found to be highly sensitive to electrode cleanliness. Trap-clearing spectra generally resemble PDI absorption spectra, but one derivative yields evidence indicating variation in trap-clearing mechanisms for different surface chemistries. Trap formation rates are measured and found to be independent of surface chemistry, contradicting a proposed silanol trapping mechanism. Finally, we develop a variation of scanning Kelvin probe microscopy that enables measurement of electric fields through a position modulation. This method avoids taking a numeric derivative of potential, which can introduce high-frequency noise into the electric field signal. Preliminary data is presented, and the theoretical basis for electric field noise in both methods is examined.

Pressure wave injuries to the nervous system caused by high-energy missile extremity impact: Part II. Distant effects on the central nervous system--a light and electron microscopic study on pigs.

PubMed

Suneson, A; Hansson, H A; Seeman, T

1990-03-01

The aim of the present study was to investigate if distant effects could be detected within the central nervous system after impact of a high-energy missile in the left thigh of young pigs. Pressure transducers implanted in various parts of the body of the animal, including the brain, recorded a short-lasting burst of oscillating pressure waves with high frequencies and large amplitudes, traversing the body tissue with a velocity of about that of sound in water (1,460 m/s). The distance between the point of impact and the brain and cervical spinal cord is in the range of 0.5 m. Macroscopic examination revealed that there was no gross brain tissue disruption or visible blood-brain barrier dysfunction. Light microscopic examination demonstrated myelin invaginations in the largest axons and shrinkage of axoplasm. Electron microscopic examination revealed a reduction in the number of microtubules, especially in the larger axons in the brainstem. Disintegration of Nissl substance, i.e., chromatolysis, was noticed after 48 hr in many Purkinje nerve cells in the cerebellum, concomitantly with the appearance of an increased frequency of association between lamellar bodies and mitochondria. Changes could also be observed in the cervical spinal cord and, at reduced frequency and extent, in the optic nerve and in other parts of the brain. These effects were evident within a few minutes after the trauma and persisted even 48 hr after the extremity injury. It is concluded that distant effects, likely to be caused by the oscillating high-frequency pressure waves, appear in the central nervous system after a high-energy missile extremity impact.

Freeze-fracture of infected plant leaves in ethanol for scanning electron microscopic study of fungal pathogens.

PubMed

Moore, Jayma A; Payne, Scott A

2012-01-01

Fungi often are found within plant tissues where they cannot be visualized with the scanning electron microscope (SEM). We present a simple way to reveal cell interiors while avoiding many common causes of artifact. Freeze-fracture of leaf tissue using liquid nitrogen during the 100% ethanol step of the dehydration process just before critical point drying is useful in exposing intracellular fungi to the SEM.

Clinical Investigation Program Report Control Symbol MED 300.

DTIC Science & Technology

1983-10-01

13 Agent Induced Delay of Gastric Emptying. (0) (PR) (P) 1979 The Experimental Fat Embolism Syndrome: An Electron 15 Microscopic Study of Lung in...1981 Investigation of Chronic Phantom Pain. (0) (PR) (P) 25 v Year Page Initiated 1981 Experimental Fat Embolism Syndrome: Basic Studies and 26...14 Detail Summary Sheet Date 3 Oct 83 Prot No.: 79-21 Status: Ongoing Title: The Experimental Fat Embolism Syndrome: An Electron Microscopic Study of

High-resolution, cryogenic, side-entry type specimen stage

DOEpatents

King, Wayne E.; Merkle, Karl L.

1979-01-01

A high-resolution, cryogenic side-entry type specimen stage includes a copper block within which a specimen can be positioned in the electron beam of an electron microscope, one end of the copper block constituting a specimen heat exchanger, means for directing a flow of helium at cryogenic temperature into the heat exchanger, and electrical leads running from the specimen to the exterior of the microscope for four point D.C. electrical resistivity measurements.

The Enhanced Driver’s License: Collateral Gains or Collateral Damage?

DTIC Science & Technology

2012-12-01

fact, are only detectible under a high- powered electron microscope. The indication, thus, is that the improvements made to the driver’s license...security environment, say airport security, there is no time to analyze driver’s licenses under a high- powered electron microscope to ensure they are...95 Advancements in recent decades have reduced the size and cost of RFID technology and as such, have increased the number of purposes ( supply

Low Voltage Electron Beam Lithography

DTIC Science & Technology

1994-01-01

September 1970 (Societe Franaise do Microscopic Elecuouique, Plaris, 1970) Vol. 2, p. 55. [31 H . C. Pfeiffer, "Basic limitations of probefonning systems...USA (editors: 0. Jobari and I. Corvin). [4) T. Groves, D. L Hunmond, H . Kuo, ’Elecmnm-beam broadening effct caused by discreteness of space charge...Electron Microscope Gun". Br. J. Appi. Phys.. February 1952, pp. 40-46. M. E. Haine, P. A. Einstein, and P. H . Brocherd. "Resistance Bias

Linear, Single-Stranded Deoxyribonucleic Acid Isolated from Kilham Rat Virus

PubMed Central

Salzman, Lois Ann; White, Wesley L.; Kakefuda, Tsuyoshi

1971-01-01

Kilham rat virus (KRV) was grown in a rat nephroma cell line and was purified by two isopycnic centrifugations in cesium chloride. The virus contains single-stranded deoxyribonucleic acid (DNA) with a molecular weight of approximately 1.6 × 106. The DNA was extracted from the virion by both phenol extraction and by 2% sodium dodecyl sulfate at 50 C. KRV DNA, extracted by both procedures, was observed in an electron microscope by using a cytochrome c or diethylaminoethyldextran monolayer. The DNA was also exposed to exonuclease I, an enzyme which hydrolyzes specifically linear, single-stranded DNA. Hydrolysis of 70 to 80% of the DNA was observed. Both the enzymatic and the electron microscope studies support the conclusion that extracted KRV DNA is a single-stranded, linear molecule. The length of the DNA was measured in the electron microscope and determined to be 1.505 ± 0.206 μm. Images PMID:4327590

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

Henn, T.; Kiessling, T., E-mail: tobias.kiessling@physik.uni-wuerzburg.de; Ossau, W.

We describe a two-color pump-probe scanning magneto-optical Kerr effect microscope which we have developed to investigate electron spin phenomena in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution. The key innovation of our microscope is the usage of an ultrafast “white light” supercontinuum fiber-laser source which provides access to the whole visible and near-infrared spectral range. Our Kerr microscope allows for the independent selection of the excitation and detection energy while avoiding the necessity to synchronize the pulse trains of two separate picosecond laser systems. The ability to independently tune the pump and probe wavelength enables themore » investigation of the influence of excitation energy on the optically induced electron spin dynamics in semiconductors. We demonstrate picosecond real-space imaging of the diffusive expansion of optically excited electron spin packets in a (110) GaAs quantum well sample to illustrate the capabilities of the instrument.« less

A densitometric analysis of commercial 35mm films

NASA Technical Reports Server (NTRS)

Hammond, Ernest C., Jr.; Ruffin, Christopher, III

1989-01-01

IIaO films have been subjected to various sensitometric tests. The have included thermal and aging effects and reciprocity failure studies. In order to compare the special IIaO film with popular brands of 35 mm films and their possible use in astrophotography, Agfa, Fuji and Kodak print and slide formats, as well as black and white and color formats, were subjected to sensitometric, as well as densitometric analysis. A scanning electron microscope was used to analyze grain structure size, and shape as a function of both speed and brand. Preliminary analysis of the grain structure using an ISI-SS40 scanning electron microscope indicates that the grain sizes for darker densities are much larger than the grain size for lighter densities. Researchers analyze the scanning electron microscope findings of the various grains versus densities as well as enhancement of the grains, using the IP-8500 Digital Image Processor.

Artificial submicron or nanometer speckle fabricating technique and electron microscope speckle photography

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

Liu Zhanwei; Xie Huimin; Fang Daining

2007-03-15

In this article, a novel artificial submicro- or nanometer speckle fabricating technique is proposed by taking advantage of submicro or nanometer particles. In the technique, submicron or nanometer particles were adhered to an object surface by using ultrasonic dispersing technique. The particles on the object surface can be regarded as submicro or nanometer speckle by using a scanning electronic microscope at a special magnification. In addition, an electron microscope speckle photography (EMSP) method is developed to measure in-plane submicron or nanometer deformation of the object coated with the artificial submicro or nanometer speckles. The principle of artificial submicro or nanometermore » speckle fabricating technique and the EMSP method are discussed in detail in this article. Some typical applications of this method are offered. The experimental results verified that the artificial submicro or nanometer speckle fabricating technique and EMSP method is feasible.« less

Multi-walled carbon nanotubes decorated by platinum catalyst nanoparticles--examination and microanalysis using scanning and transmission electron microscopies.

PubMed

Guinel, M J-F; Brodusch, N; Verde-Gómez, Y; Escobar-Morales, B; Gauvin, R

2013-10-01

Carbon nanotubes (CNTs) decorated with platinum (Pt) nanoparticles (NPs) have been characterized using a cold field-emission scanning electron microscope (SEM) and a high resolution field-emission transmission electron microscope (TEM). With this particular composite material, the complementary nature of the two instruments was demonstrated. Although the long CNTs were found to be mostly bent and defective in some parts, the nucleation of Pt occurred randomly and uniformly covered the CNTs. The NPs displayed a large variation in size, were sometimes defective with twins and stacking faults, and were found to be faceted with the presence of surface steps. The shape and size of the NPs and the presence of defects may have significant consequences on the activity of the Pt catalyst material. Also, thin layers of platinum oxide were identified on the surface of some NPs. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

In situ microscopy of rapidly heated nano-Al and nano-Al/WO{sub 3} thermites

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

Sullivan, Kyle T.; Zachariah, Michael R.; Chiou, Wen-An

2010-09-27

The initiation and reaction mechanism of nano-Al and nano-Al thermites in rapid heating environments is investigated in this work. A semiconductor-based grid/stage was used, capable of in situ heating of a sample from room temperature to 1473 K, and at a rate of 10{sup 6} K/s, inside an electron microscope. Nano-Al was rapidly heated in a transmission electron microscope, and before and after images indicate that the aluminum migrates through the shell, consistent with a diffusion-based mechanism. A nano-Al/WO{sub 3} composite was then heated in a scanning electron microscope. The results indicate that a reactive sintering mechanism is occurring formore » the nano-Al/WO{sub 3} thermite, as the products are found to be in surface contact and significantly deformed after the heating pulse.« less

Irradiation Creep in Graphite

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

Ubic, Rick; Butt, Darryl; Windes, William

2014-03-13

An understanding of the underlying mechanisms of irradiation creep in graphite material is required to correctly interpret experimental data, explain micromechanical modeling results, and predict whole-core behavior. This project will focus on experimental microscopic data to demonstrate the mechanism of irradiation creep. High-resolution transmission electron microscopy should be able to image both the dislocations in graphite and the irradiation-induced interstitial clusters that pin those dislocations. The team will first prepare and characterize nanoscale samples of virgin nuclear graphite in a transmission electron microscope. Additional samples will be irradiated to varying degrees at the Advanced Test Reactor (ATR) facility and similarlymore » characterized. Researchers will record microstructures and crystal defects and suggest a mechanism for irradiation creep based on the results. In addition, the purchase of a tensile holder for a transmission electron microscope will allow, for the first time, in situ observation of creep behavior on the microstructure and crystallographic defects.« less

Scanning electron microscope cathodoluminescence imaging of subgrain boundaries, twins and planar deformation features in quartz

NASA Astrophysics Data System (ADS)

Hamers, M. F.; Pennock, G. M.; Drury, M. R.

2017-04-01

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.

Structure of IgG and IgY molecules in ribosome-antibody complexes as studied by electron microscopy.

PubMed

Noll, F; Lutsch, G; Bielka, H

1982-03-01

The overall shape and dimensions of IgG (rabbit) and IgY (chicken) antibodies against ribosomal proteins have been studied in electron micrographs of ribosome-antibody complexes. The antibodies appear as Y-shaped molecules with an angle of about 90 degrees between their Fab arms. The length of one Fab arm amounts to about 10 nm. No differences between the IgG and IgY molecules could be detected electron microscopically. The data obtained on the shape of IgG and IgY correlate with those of earlier electron microscopic studies while the determined size of the Fab arms is in the range found by scattering methods.

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

Lorut, F.; Imbert, G.; Roggero, A.

In this paper, we investigate the tendency of porous low-K dielectrics (also named Ultra Low-K, ULK) behavior to shrink when exposed to the electron beam of a scanning electron microscope. Various experimental electron beam conditions have been used for irradiating ULK thin films, and the resulting shrinkage has been measured through use of an atomic force microscope tool. We report the shrinkage to be a fast, cumulative, and dose dependent effect. Correlation of the shrinkage with incident electron beam energy loss has also been evidenced. The chemical modification of the ULK films within the interaction volume has been demonstrated, withmore » a densification of the layer and a loss of carbon and hydrogen elements being observed.« less

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

NASA Astrophysics Data System (ADS)

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

2011-06-01

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

The PC9A Filter Screening Tool

DTIC Science & Technology

2016-02-01

conjunction with an optical microscope for identification of other important debris such as glass beads. The FST has now been installed at RAAF East...conservative screening limits need to be sent for detailed laboratory analysis. Laboratory analysis has traditionally involved a manual microscopic ...Electron Microscope with Energy Dispersive Spectroscopy (SEM EDS) to determine the composition and likely source. The Engine Maintenance Manual

Three dimensional profile measurement using multi-channel detector MVM-SEM

NASA Astrophysics Data System (ADS)

Yoshikawa, Makoto; Harada, Sumito; Ito, Keisuke; Murakawa, Tsutomu; Shida, Soichi; Matsumoto, Jun; Nakamura, Takayuki

2014-07-01

In next generation lithography (NGL) for the 1x nm node and beyond, the three dimensional (3D) shape measurements such as side wall angle (SWA) and height of feature on photomask become more critical for the process control. Until today, AFM (Atomic Force Microscope), X-SEM (cross-section Scanning Electron Microscope) and TEM (Transmission Electron Microscope) tools are normally used for 3D measurements, however, these techniques require time-consuming preparation and observation. And both X-SEM and TEM are destructive measurement techniques. This paper presents a technology for quick and non-destructive 3D shape analysis using multi-channel detector MVM-SEM (Multi Vision Metrology SEM), and also reports its accuracy and precision.

An in-plane magnetic chiral dichroism approach for measurement of intrinsic magnetic signals using transmitted electrons

PubMed Central

Song, Dongsheng; Tavabi, Amir H.; Li, Zi-An; Kovács, András; Rusz, Ján; Huang, Wenting; Richter, Gunther; Dunin-Borkowski, Rafal E.; Zhu, Jing

2017-01-01

Electron energy-loss magnetic chiral dichroism is a powerful technique that allows the local magnetic properties of materials to be measured quantitatively with close-to-atomic spatial resolution and element specificity in the transmission electron microscope. Until now, the technique has been restricted to measurements of the magnetic circular dichroism signal in the electron beam direction. However, the intrinsic magnetization directions of thin samples are often oriented in the specimen plane, especially when they are examined in magnetic-field-free conditions in the transmission electron microscope. Here, we introduce an approach that allows in-plane magnetic signals to be measured using electron magnetic chiral dichroism by selecting a specific diffraction geometry. We compare experimental results recorded from a cobalt nanoplate with simulations to demonstrate that an electron magnetic chiral dichroism signal originating from in-plane magnetization can be detected successfully. PMID:28504267

Electron beam analysis of particulate cometary material

NASA Technical Reports Server (NTRS)

Bradley, John

1989-01-01

Electron microscopy will be useful for characterization of inorganic dust grains in returned comet nucleus samples. The choice of instrument(s) will depend primarily on the nature of the samples, but ultimately a variety of electron-beam methods could be employed. Scanning and analytical (transmission) electron microscopy are the logical choise for morphological, mineralogical, and bulk chemical analyses of dust grains removed from ices. It may also be possible to examine unmelted ice/dust mixtures using an environmental scanning electron microscope equipped with a cryo-transfer unit and a cold stage. Electron microscopic observations of comet nuclei might include: (1) porosities of dust grains; (2) morphologies and microstructures of individual mineral grains; (3) relative abundances of olivine, pyroxene, and glass; and (4) the presence of phases that might have resulted from aqueous alteration (layer silicates, carbonates, sulfates).

Microscopy with slow electrons: from LEEM to XPEEM

ScienceCinema

Bauer, Ernst [Arizona State University, Phoenix, Arizona, United States

2017-12-09

The short penetration and escape depth of electrons with energies below 1 keV make them ideally suited for the study of surfaces and ultrathin films. The combination of the low energy electrons and the high lateral resolution of a microscope produces a powerful method for the characterization of nanostructures on bulk samples, in particular if the microscope is equipped with an imaging energy filter and connected to a synchrotron radiation source. Comprehensive characterization by imaging, diffraction, and spectroscope of the structural, chemical, and magnetic properties is then possible. The Talk will describe the various imaging techniques in using reflected and emitted electrons in low-energy electron microscopy (LEEM) and x-ray photoemission electron microscopy (XPEEM), with an emphasis on magnetic materials with spin-polarized LEEM and x-ray magnetic circular dichroism PEEM. The talk with end with an outlook on future possibilities.

Phase contrast in high resolution electron microscopy

DOEpatents

Rose, H.H.

1975-09-23

This patent relates to a device for developing a phase contrast signal for a scanning transmission electron microscope. The lens system of the microscope is operated in a condition of defocus so that predictable alternate concentric regions of high and low electron density exist in the cone of illumination. Two phase detectors are placed beneath the object inside the cone of illumination, with the first detector having the form of a zone plate, each of its rings covering alternate regions of either higher or lower electron density. The second detector is so configured that it covers the regions of electron density not covered by the first detector. Each detector measures the number of electrons incident thereon and the signal developed by the first detector is subtracted from the signal developed by the record detector to provide a phase contrast signal. (auth)

Missing defects? A comparison of microscopic and macroscopic approaches to identifying linear enamel hypoplasia.

PubMed

Hassett, Brenna R

2014-03-01

Linear enamel hypoplasia (LEH), the presence of linear defects of dental enamel formed during periods of growth disruption, is frequently analyzed in physical anthropology as evidence for childhood health in the past. However, a wide variety of methods for identifying and interpreting these defects in archaeological remains exists, preventing easy cross-comparison of results from disparate studies. This article compares a standard approach to identifying LEH using the naked eye to the evidence of growth disruption observed microscopically from the enamel surface. This comparison demonstrates that what is interpreted as evidence of growth disruption microscopically is not uniformly identified with the naked eye, and provides a reference for the level of consistency between the number and timing of defects identified using microscopic versus macroscopic approaches. This is done for different tooth types using a large sample of unworn permanent teeth drawn from several post-medieval London burial assemblages. The resulting schematic diagrams showing where macroscopic methods achieve more or less similar results to microscopic methods are presented here and clearly demonstrate that "naked-eye" methods of identifying growth disruptions do not identify LEH as often as microscopic methods in areas where perikymata are more densely packed. Copyright © 2013 Wiley Periodicals, Inc.

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

PubMed

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

2017-05-01

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

KLASS: Kennedy Launch Academy Simulation System

NASA Technical Reports Server (NTRS)

Garner, Lesley C.

2007-01-01

Software provides access to many sophisticated scientific instrumentation (Scanning Electron Microscope (SEM), a Light Microscope, a Scanning Probe Microscope (covering Scanning Tunneling, Atomic Force, and Magnetic Force microscopy), and an Energy Dispersive Spectrometer for the SEM). Flash animation videos explain how each of the instruments work. Videos on how they are used at NASA and the sample preparation. Measuring and labeling tools provided with each instrument. Hands on experience of controlling the virtual instrument to conduct investigations, much like the real scientists at NASA do. Very open architecture. Open source on SourceForge. Extensive use of XML Target audience is high school and entry-level college students. "Many beginning students never get closer to an electron microscope than the photos in their textbooks. But anyone can get a sense of what the instrument can do by downloading this simulator from NASA's Kennedy Space Center." Science Magazine, April 8th, 2005

A Monte Carlo model of hot electron trapping and detrapping in SiO2

NASA Astrophysics Data System (ADS)

Kamocsai, R. L.; Porod, W.

1991-02-01

High-field stressing and oxide degradation of SiO2 are studied using a microscopic model of electron heating and charge trapping and detrapping. Hot electrons lead to a charge buildup in the oxide according to the dynamic trapping-detrapping model by Nissan-Cohen and co-workers [Y. Nissan-Cohen, J. Shappir, D. Frohman-Bentchkowsky, J. Appl. Phys. 58, 2252 (1985)]. Detrapping events are modeled as trap-to-band impact ionization processes initiated by high energy conduction electrons. The detailed electronic distribution function obtained from Monte Carlo transport simulations is utilized for the determination of the detrapping rates. We apply our microscopic model to the calculation of the flat-band voltage shift in silicon dioxide as a function of the electric field, and we show that our model is able to reproduce the experimental results. We also compare these results to the predictions of the empirical trapping-detrapping model which assumes a heuristic detrapping cross section. Our microscopic theory accounts for the nonlocal nature of impact ionization which leads to a dark space close to the injecting cathode, which is unaccounted for in the empirical model.

Microscopic Electron Dynamics in Metal Nanoparticles for Photovoltaic Systems.

PubMed

Kluczyk, Katarzyna; Jacak, Lucjan; Jacak, Witold; David, Christin

2018-06-25

Nanoparticles—regularly patterned or randomly dispersed—are a key ingredient for emerging technologies in photonics. Of particular interest are scattering and field enhancement effects of metal nanoparticles for energy harvesting and converting systems. An often neglected aspect in the modeling of nanoparticles are light interaction effects at the ultimate nanoscale beyond classical electrodynamics. Those arise from microscopic electron dynamics in confined systems, the accelerated motion in the plasmon oscillation and the quantum nature of the free electron gas in metals, such as Coulomb repulsion and electron diffusion. We give a detailed account on free electron phenomena in metal nanoparticles and discuss analytic expressions stemming from microscopic (Random Phase Approximation—RPA) and semi-classical (hydrodynamic) theories. These can be incorporated into standard computational schemes to produce more reliable results on the optical properties of metal nanoparticles. We combine these solutions into a single framework and study systematically their joint impact on isolated Au, Ag, and Al nanoparticles as well as dimer structures. The spectral position of the plasmon resonance and its broadening as well as local field enhancement show an intriguing dependence on the particle size due to the relevance of additional damping channels.

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

NASA Astrophysics Data System (ADS)

Vynnyk, Taras; Scheuer, Renke; Reithmeier, Eduard

2011-06-01

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

SPE-LEEM Studies on the Surface and Electronic Structure of 2-D Transition Metal Dichalcogenides (Part II)

NASA Astrophysics Data System (ADS)

Jin, Wencan; Yeh, Po-Chun; Zaki, Nader; Zhang, Datong; Sadowski, Jerzy; Al-Mahboob, Abdullah; van de Zande, Arend; Chenet, Daniel; Dadap, Jerry; Herman, Irving; Sutter, Peter; Hone, James; Osgood, Richard

2014-03-01

In this work, we studied the surface and electronic structure of monolayer and few-layer exfoliated MoS2 and WSe2, as well as chemical-vapor-deposition (CVD) grown MoS2, using Spectroscopic Photoemission and Low Energy Electron Microscope (SPE-LEEM). LEEM measurements reveal that, unlike exfoliated MoS2, CVD-grown MoS2 exhibits grain-boundary alterations due to surface strain. However, LEEM and micro-probe low energy electron diffraction show that the quality of CVD-grown MoS2 is comparable to that of exfoliated MoS2. Micrometer-scale angle-resolved photoemission spectroscopy (ARPES) measurement on exfoliated MoS2 and WSe2 single-crystals provides direct evidence for the shifting of the valence band maximum from Γ to K, when the layer number is thinned down to one, as predicted by density functional theory. Our measurements of the k-space resolved electronic structure allow for further comparison with other theoretical predictions and with transport measurements. This work is supported by DOE grant DE-FG 02-04-ER-46157, research carried out in part at the CFN and NSLS, Brookhaven National Laboratory.

Tomography experiment of an integrated circuit specimen using 3 MeV electrons in the transmission electron microscope.

PubMed

Zhang, Hai-Bo; Zhang, Xiang-Liang; Wang, Yong; Takaoka, Akio

2007-01-01

The possibility of utilizing high-energy electron tomography to characterize the micron-scale three dimensional (3D) structures of integrated circuits has been demonstrated experimentally. First, electron transmission through a tilted SiO(2) film was measured with an ultrahigh-voltage electron microscope (ultra-HVEM) and analyzed from the point of view of elastic scattering of electrons, showing that linear attenuation of the logarithmic electron transmission still holds valid for effective specimen thicknesses up to 5 microm under 2 MV accelerating voltages. Electron tomography of a micron-order thick integrated circuit specimen including the Cu/via interconnect was then tried with 3 MeV electrons in the ultra-HVEM. Serial projection images of the specimen tilted at different angles over the range of +/-90 degrees were acquired, and 3D reconstruction was performed with the images by means of the IMOD software package. Consequently, the 3D structures of the Cu lines, via and void, were revealed by cross sections and surface rendering.

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

PubMed

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

2017-07-01

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

Dark-field imaging based on post-processed electron backscatter diffraction patterns of bulk crystalline materials in a scanning electron microscope.

PubMed

Brodusch, Nicolas; Demers, Hendrix; Gauvin, Raynald

2015-01-01

Dark-field (DF) images were acquired in the scanning electron microscope with an offline procedure based on electron backscatter diffraction (EBSD) patterns (EBSPs). These EBSD-DF images were generated by selecting a particular reflection on the electron backscatter diffraction pattern and by reporting the intensity of one or several pixels around this point at each pixel of the EBSD-DF image. Unlike previous studies, the diffraction information of the sample is the basis of the final image contrast with a pixel scale resolution at the EBSP providing DF imaging in the scanning electron microscope. The offline facility of this technique permits the selection of any diffraction condition available in the diffraction pattern and displaying the corresponding image. The high number of diffraction-based images available allows a better monitoring of deformation structures compared to electron channeling contrast imaging (ECCI) which is generally limited to a few images of the same area. This technique was applied to steel and iron specimens and showed its high capability in describing more rigorously the deformation structures around micro-hardness indents. Due to the offline relation between the reference EBSP and the EBSD-DF images, this new technique will undoubtedly greatly improve our knowledge of deformation mechanism and help to improve our understanding of the ECCI contrast mechanisms. Copyright © 2014 Elsevier B.V. All rights reserved.

Scanning Electron Microscopic Evaluation of Several Resharpening Techniques.

DTIC Science & Technology

1982-08-19

AD-AI20 320 ARMY INST OF DENTAL RESEARCH WASHINGTON OC F/6 6/5 SCANNING ELECTRON MICROSCOPIC EVALUATION OF SEVERAL RESHARPENIN-ETC(U) UNLASSIFIE D...NIT NUMBERS US Army Institute of Dental Research Walter Reed Army Medical Center N/A Washington, DC 20012 it. CONTROLLING OFFICE NAME AND ADORESS I...several resharpening techniques by Donald J. DeNucci, DDS, MS and Carson L. Mader, DMD, MSD United States Army Institute of Dental Research Walter Reed

A Transmission Electron Microscope Investigation of Space Weathering Effects in Hayabusa Samples

NASA Technical Reports Server (NTRS)

Keller, Lindsay P.; Berger, Eve L.

2014-01-01

The Hayabusa mission to asteroid 25143 Itokawa successfully returned the first direct samples of the regolith from the surface of an asteroid. The Hayabusa samples thus present a special opportunity to directly investigate the evolution of asteroidal surfaces, from the development of the regolith to the study of the more complex effects of space weathering. Here we describe the mineralogy, microstructure and composition of three Hayabusa mission particles using transmission electron microscope (TEM) techniques

Technique to quantitatively measure magnetic properties of thin structures at <10 NM spatial resolution

DOEpatents

Bajt, Sasa

2003-07-08

A highly sensitive and high resolution magnetic microscope images magnetic properties quantitatively. Imaging is done with a modified transmission electron microscope that allows imaging of the sample in a zero magnetic field. Two images from closely spaced planes, one in focus and one slightly out of focus, are sufficient to calculate the absolute values of the phase change imparted to the electrons, and hence obtain the magnetization vector field distribution.

Applications of the Analytical Electron Microscope to Materials Science

NASA Technical Reports Server (NTRS)

Goldstein, J. I.

1992-01-01

In the last 20 years, the analytical electron microscope (AEM) as allowed investigators to obtain chemical and structural information from less than 50 nanometer diameter regions in thin samples of materials and to explore problems where reactions occur at boundaries and interfaces or within small particles or phases in bulk samples. Examples of the application of the AEM to materials science problems are presented in this paper and demonstrate the usefulness and the future potential of this instrument.

A 25% tannic acid solution as a root canal irrigant cleanser: a scanning electron microscope study.

PubMed

Bitter, N C

1989-03-01

A scanning electron microscope was used to evaluate the cleansing properties of a 25% tannic acid solution on the dentinal surface in the pulp chamber of endodontically prepared teeth. This was compared with the amorphous smear layer of the canal with the use of hydrogen peroxide and sodium hypochlorite solution as an irrigant. The tannic acid solution removed the smear layer more effectively than the regular cleansing agent.

Zeiss ΣIGMA VP-FE-SEM User Guide

EPA Science Inventory

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

The hard parts (trophi) of the rotifer mastax do contain chitin: evidence from studies on Brachionus plicatilis.

PubMed

Klusemann, J; Kleinow, W; Peters, W

1990-01-01

The jaws (trophi) of the rotifer Brachionus plicatilis are soluble in strong acids but are resistant to long treatments by strong alkali. They show the same buoyant density as chitin and also as the chitin-containing layers of rotifer egg-shells. The presence of chitin in these structures was confirmed using the following techniques: chitosan-tests, thin-layer chromatography of trophi-hydrolysates which revealed glucosamine, by dissolving trophi with chitinase and electron microscopic WGA/gold-labelling. The content of chitin in the trophi was estimated by two different methods to be approx. 64% (50-75%).

Deformation behavior of austenitic stainless steel at deep cryogenic temperatures

NASA Astrophysics Data System (ADS)

Han, Wentuo; Liu, Yuchen; Wan, Farong; Liu, Pingping; Yi, Xiaoou; Zhan, Qian; Morrall, Daniel; Ohnuki, Somei

2018-06-01

The nonmagnetic austenite steels are the jacket materials for low-temperature superconductors of fusion reactors. The present work provides evidences that austenites transform to magnetic martensite when deformation with a high-strain is imposed at 77 K and 4.2 K. The 4.2 K test is characterized by serrated yielding that is related to the specific motion of dislocations and phase transformations. The in-situ transmission electron microscope (TEM) observations in nanoscale reveal that austenites achieve deformation by twinning under low-strain conditions at deep cryogenic temperatures. The generations of twins, martensitic transformations, and serrated yielding are in order of increasing difficulty.

A SEM-correlation of the anatomy of the vitreous body: making visible the invisible.

PubMed

Jongebloed, W L; Humalda, D; Worst, J F

1986-12-30

The naked human vitreous (sclera, iris and cornea removed) suspended in water does not reveal inner structures. After ink injection into the vitreous, the presence of different compartments and the existence of cisterns becomes evident. A concept of the internal system of cisterns is given on the basis of stereoscopic-lightmicroscopic images. An attempt is made to correlate images of the complete vitreous body, obtained with a stereo-lightmicroscope, with images of segments of cisternal walls produced with a scanning electron-microscope (SEM). A comparison is made between SEM-images of the vitreous bodies of human and rabbit eyes.

Surface crystalline phases and nanoindentation hardness of explanted zirconia femoral heads.

PubMed

Catledge, Shane A; Cook, Monique; Vohra, Yogesh K; Santos, Erick M; McClenny, Michelle D; David Moore, K

2003-10-01

One new and nine explanted zirconia femoral heads were studied using glancing angle X-ray diffraction, scanning electron microscopy, and nanoindentation hardness techniques. All starting zirconia implants consisted only of tetragonal zirconia polycrystals (TZP). For comparison, one explanted alumina femoral head was also studied. Evidence for a surface tetragonal-to-monoclinic zirconia phase transformation was observed in some implants, the extent of which was varied for different in-service conditions. A strong correlation was found between increasing transformation to the monoclinic phase and decreasing surface hardness. Microscopic investigations of some of the explanted femoral heads revealed ultra high molecular weight polyethylene and metallic transfer wear debris.

Evidence of a temperature transition for denuded zone formation in nanocrystalline Fe under He irradiation

DOE PAGES

El-Atwani, Osman; Nathaniel II, James E.; Leff, Asher C.; ...

2016-10-18

Nanocrystalline materials are radiation-tolerant materials’ candidates due to their high defect sink density. Here, nanocrystalline iron films were irradiated with 10 keV helium ions in situ in a transmission electron microscope at elevated temperatures. Grain-size-dependent bubble density changes and denuded zone occurrence were observed at 700 K, but not at 573 K. This transition, attributed to increased helium–vacancy migration at elevated temperatures, suggests that nanocrystalline microstructures are more resistant to swelling at 700 K due to decreased bubble density. Finally, denuded zone formation had no correlation with grain size and misorientation angle under the conditions studied.

Mechanical and electrical characterization of semiconducting ZnO nanorings by direct nano-manipulation

NASA Astrophysics Data System (ADS)

Mai, Wenjie; Zhang, Long; Gu, Yudong; Huang, Shiqing; Zhang, Zongfu; Lao, Changshi; Yang, Peihua; Qiang, Pengfei; Chen, Zhongwei

2012-08-01

With assistance from a nano-manipulator system inside a scanning electron microscope chamber, mechanical and electrical properties of ZnO nanorings were investigated. The change of a fractured nanoring to nearly straight nanobelts was strong evidence to support the previously proposed electrostatic-force-induced self-coiling model, and our computational simulation results indicated the fracture force was 25-30 μN. The contact between a tungsten tip of the manipulator and a ZnO nanoring was confirmed as the Schottky type; therefore, the change of I-V curves of the nanoring under compression was attributed to the Schottky barrier height changes.

Silver nanoparticle production by Rhizopus stolonifer and its antibacterial activity against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae

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

Banu, Afreen; Rathod, Vandana, E-mail: drvandanarathod@rediffmail.com; Ranganath, E.

Highlights: {yields} Silver nanoparticle production by using Rhizopus stolonifer. {yields} Antibacterial activity of silver nanoparticles against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae. {yields} Synergistic effect of antibiotics with silver nanoparticles towards ESBL-strains. {yields} Characterization of silver nanoparticles made by UV-vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, atomic force microscopy (AFM). -- Abstract: This report focuses on the synthesis of silver nanoparticles using the fungus, Rhizopus stolonifer and its antimicrobial activity. Research in nanotechnology highlights the possibility of green chemistry pathways to produce technologically important nanomaterials. Characterization of newly synthesized silvermore » nanoparticles was made by UV-visible absorption spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy and atomic force microscope (AFM). TEM micrograph revealed the formation of spherical nanoparticles with size ranging between 3 and 20 nm. The biosynthesized silver nanoparticles (AgNPs) showed excellent antibacterial activity against ESBL-strains which includes E. coli, Proteus. sp. and Klebsiella sp.« less

In situ hybridization at the electron microscope level: localization of transcripts on ultrathin sections of Lowicryl K4M-embedded tissue using biotinylated probes and protein A-gold complexes

PubMed Central

1986-01-01

A technique has been developed for localizing hybrids formed in situ on semi-thin and ultrathin sections of Lowicryl K4M-embedded tissue. Biotinylated dUTP (Bio-11-dUTP and/or Bio-16-dUTP) was incorporated into mitochondrial rDNA and small nuclear U1 probes by nick- translation. The probes were hybridized to sections of Drosophila ovaries and subsequently detected with an anti-biotin antibody and protein A-gold complex. On semi-thin sections, probe detection was achieved by amplification steps with anti-protein A antibody and protein A-gold with subsequent silver enhancement. At the electron microscope level, specific labeling was obtained over structures known to be the site of expression of the appropriate genes (i.e., either over mitochondria or over nuclei). The labeling pattern at the light microscope level (semi-thin sections) was consistent with that obtained at the electron microscope level. The described nonradioactive procedures for hybrid detection on Lowicryl K4M-embedded tissue sections offer several advantages: rapid signal detection: superior morphological preservation and spatial resolution; and signal-to-noise ratios equivalent to radiolabeling. PMID:3084498

Effects of Al3(Sc,Zr) and Shear Band Formation on the Tensile Properties and Fracture Behavior of Al-Mg-Sc-Zr Alloy

NASA Astrophysics Data System (ADS)

Huang, Hongfeng; Jiang, Feng; Zhou, Jiang; Wei, Lili; Qu, Jiping; Liu, Lele

2015-11-01

The mechanical properties and microstructures of Al-6Mg-0.25Sc-0.1Zr alloy (wt.%) during annealing were investigated by means of uniaxial tensile testing, optical microscope, scanning electron microscope, transmission electron microscope, and high-resolution transmission electron microscope. The results show that a large number of micro and grain-scale shear bands form in this alloy after cold rolling. As the tensile-loading force rises, strain softening would generate in shear bands, resulting in the occurrence of shear banding fracture in cold-rolled Al-Mg-Sc-Zr alloys. Recrystallization takes place preferentially in shear bands during annealing. Due to the formation of coarse-grain bands constructed by new subgrains, recrystallization softening tends to occur in these regions. During low-temperature annealing, recrystallization is inhibited by nano-scale Al3(Sc,Zr) precipitates which exert significant coherency strengthening and modulus hardening. However, the strengthening effect of Al3(Sc,Zr) decreases with the increasing of particle diameter at elevated annealing temperature. The mechanical properties of the recrystallized Al-Mg-Sc-Zr alloy decrease to a minimum level, and the fracture plane exhibits pure ductile fracture characteristics.

Three-dimensional reconstruction of highly complex microscopic samples using scanning electron microscopy and optical flow estimation.

PubMed

Baghaie, Ahmadreza; Pahlavan Tafti, Ahmad; Owen, Heather A; D'Souza, Roshan M; Yu, Zeyun

2017-01-01

Scanning Electron Microscope (SEM) as one of the major research and industrial equipment for imaging of micro-scale samples and surfaces has gained extensive attention from its emerge. However, the acquired micrographs still remain two-dimensional (2D). In the current work a novel and highly accurate approach is proposed to recover the hidden third-dimension by use of multi-view image acquisition of the microscopic samples combined with pre/post-processing steps including sparse feature-based stereo rectification, nonlocal-based optical flow estimation for dense matching and finally depth estimation. Employing the proposed approach, three-dimensional (3D) reconstructions of highly complex microscopic samples were achieved to facilitate the interpretation of topology and geometry of surface/shape attributes of the samples. As a byproduct of the proposed approach, high-definition 3D printed models of the samples can be generated as a tangible means of physical understanding. Extensive comparisons with the state-of-the-art reveal the strength and superiority of the proposed method in uncovering the details of the highly complex microscopic samples.

Electronic structure of polycrystalline CVD-graphene revealed by Nano-ARPES

NASA Astrophysics Data System (ADS)

Chen, Chaoyu; Avila, José; Asensio, Maria C.

2017-06-01

The ability to explore electronic structure and their role in determining material’s macroscopic behaviour is essential to explain and engineer functions of material and device. Since its debut in 2004, graphene has attracted global research interest due to its unique properties. Chemical vapor deposition (CVD) has emerged as an important method for the massive preparation and production of graphene for various applications. Here by employing angle-resolved photoemission spectroscopy with nanoscale spatial resolution ˜ 100 nm (Nano-ARPES), we describe the approach to measure the electronic structure of polycrystalline graphene on copper foils, demonstrating the power of Nano-ARPES to detect the electronic structure of microscopic single crystalline domains, being fully compatible with conventional ARPES. Similar analysis could be employed to other microscopic materials

Electron microscopy of whole cells in liquid with nanometer resolution

PubMed Central

de Jonge, N.; Peckys, D. B.; Kremers, G. J.; Piston, D. W.

2009-01-01

Single gold-tagged epidermal growth factor (EGF) molecules bound to cellular EGF receptors of fixed fibroblast cells were imaged in liquid with a scanning transmission electron microscope (STEM). The cells were placed in buffer solution in a microfluidic device with electron transparent windows inside the vacuum of the electron microscope. A spatial resolution of 4 nm and a pixel dwell time of 20 μs were obtained. The liquid layer was sufficiently thick to contain the cells with a thickness of 7 ± 1 μm. The experimental findings are consistent with a theoretical calculation. Liquid STEM is a unique approach for imaging single molecules in whole cells with significantly improved resolution and imaging speed over existing methods. PMID:19164524

Electron-beam-induced potentials in semiconductors: calculation and measurement with an SEM/SPM hybrid system

NASA Astrophysics Data System (ADS)

Thomas, Ch; Joachimsthaler, I.; Heiderhoff, R.; Balk, L. J.

2004-10-01

In this work electron-beam-induced potentials are analysed theoretically and experimentally for semiconductors. A theoretical model is developed to describe the surface potential distribution produced by an electron beam. The distribution of generated carriers is calculated using semiconductor equations. This distribution causes a local change in surface potential, which is derived with the help of quasi-Fermi energies. The potential distribution is simulated using the model developed and measured with a scanning probe microscope (SPM) built inside a scanning electron microscope (SEM), for different samples, for different beam excitations and for different cantilever voltages of SPM. In the end, some fields of application are shown where material properties can be determined using an SEM/SPM hybrid system.

Two Further Experiments on Electron Interference

ERIC Educational Resources Information Center

Matteucci, G.; Pozzi, G.

1978-01-01

Presents the results of two experiments concerning the phenomena of the interference of probabilities and of the so called Aharonov-Bohm effect. An electron biprism and a standard electron microscope have been used for the experiments. (Author/GA)

Zernike phase-contrast electron cryotomography applied to marine cyanobacteria infected with cyanophages.

PubMed

Dai, Wei; Fu, Caroline; Khant, Htet A; Ludtke, Steven J; Schmid, Michael F; Chiu, Wah

2014-11-01

Advances in electron cryotomography have provided new opportunities to visualize the internal 3D structures of a bacterium. An electron microscope equipped with Zernike phase-contrast optics produces images with markedly increased contrast compared with images obtained by conventional electron microscopy. Here we describe a protocol to apply Zernike phase plate technology for acquiring electron tomographic tilt series of cyanophage-infected cyanobacterial cells embedded in ice, without staining or chemical fixation. We detail the procedures for aligning and assessing phase plates for data collection, and methods for obtaining 3D structures of cyanophage assembly intermediates in the host by subtomogram alignment, classification and averaging. Acquiring three or four tomographic tilt series takes ∼12 h on a JEM2200FS electron microscope. We expect this time requirement to decrease substantially as the technique matures. The time required for annotation and subtomogram averaging varies widely depending on the project goals and data volume.

Design and commissioning of an aberration-corrected ultrafast spin-polarized low energy electron microscope with multiple electron sources.

PubMed

Wan, Weishi; Yu, Lei; Zhu, Lin; Yang, Xiaodong; Wei, Zheng; Liu, Jefferson Zhe; Feng, Jun; Kunze, Kai; Schaff, Oliver; Tromp, Ruud; Tang, Wen-Xin

2017-03-01

We describe the design and commissioning of a novel aberration-corrected low energy electron microscope (AC-LEEM). A third magnetic prism array (MPA) is added to the standard AC-LEEM with two prism arrays, allowing the incorporation of an ultrafast spin-polarized electron source alongside the standard cold field emission electron source, without degrading spatial resolution. The high degree of symmetries of the AC-LEEM are utilized while we design the electron optics of the ultrafast spin-polarized electron source, so as to minimize the deleterious effect of time broadening, while maintaining full control of electron spin. A spatial resolution of 2nm and temporal resolution of 10ps (ps) are expected in the future time resolved aberration-corrected spin-polarized LEEM (TR-AC-SPLEEM). The commissioning of the three-prism AC-LEEM has been successfully finished with the cold field emission source, with a spatial resolution below 2nm. Copyright © 2017 Elsevier B.V. All rights reserved.

Colonization of cashew plants by Lasiodiplodia theobromae: Microscopical features

USDA-ARS?s Scientific Manuscript database

Lasiodiplodia theobromae is a phytopathogenic fungus causing gummosis, a threatening disease for cashew plants in Brazil. In an attempt to investigate the ultrastructural features of the pathogen colonization and its response to immunofluorescence labeling, light, confocal and electron microscope st...

Protective effects of combination of quercetin and α-tocopherol on mitochondrial dysfunction and myocardial infarct size in isoproterenol-treated myocardial infarcted rats: biochemical, transmission electron microscopic, and macroscopic enzyme mapping evidences.

PubMed

Punithavathi, V R; Stanely Mainzen Prince, P

2010-01-01

Mitochondrial dysfunction plays an important role in the pathology of myocardial infarction. We evaluated the combined protective effects of quercetin and α-tocopherol on mitochondrial damage and myocardial infarct size in isoproterenol-induced myocardia- infarcted rats. Rats were pretreated with quercetin (10 mg/kg) alone, α-tocopherol (10 mg/kg) alone, and combination of quercetin (10 mg/kg) and α-tocopherol (10 mg/kg) orally using an intragastric tube daily for 14 days. After pretreatment, rats were induced myocardial infarction by isoproterenol (100 mg/kg) at an interval of 24 h for 2 days. Isoproterenol treatment caused significant increase in mitochondrial lipid peroxides with significant decrease in mitochondrial antioxidants. Significant decrease in the activities of isocitrate, succinate, malate, and α-ketoglutarate and NADH dehydrogenases and cytochrome-c-oxidase, significant increase in calcium, and significant decrease in adenosine triphosphate were observed in mitochondria of myocardial infarcted rats. Combined pretreatment with quercetin and α-tocopherol normalized all the biochemical parameters and preserved the integrity of heart tissue and restored normal mitochondrial function in myocardial-infarcted rats. Transmission electron microscopic findings on heart mitochondria and macroscopic enzyme mapping assay on the size of myocardial infarct also correlated with these biochemical parameters. The present study showed that combined pretreatment was highly effective than single pretreatment. Copyright 2010 Wiley Periodicals, Inc.

Fracture, failure and compression behaviour of a 3D interconnected carbon aerogel (Aerographite) epoxy composite

DOE PAGES

Chandrasekaran, S.; Liebig, W. V.; Mecklenberg, M.; ...

2015-11-04

Aerographite (AG) is a mechanically robust, lightweight synthetic cellular material, which consists of a 3D interconnected network of tubular carbon [1]. The presence of open channels in AG aids to infiltrate them with polymer matrices, thereby yielding an electrical conducting and lightweight composite. Aerographite produced with densities in the range of 7–15 mg/cm 3 was infiltrated with a low viscous epoxy resin by means of vacuum infiltration technique. Detailed morphological and structural investigations on synthesized AG and AG/epoxy composite were performed by scanning electron microscopic techniques. Our present study investigates the fracture and failure of AG/epoxy composites and its energymore » absorption capacity under compression. The composites displayed an extended plateau region when uni-axially compressed, which led to an increase in energy absorption of ~133% per unit volume for 1.5 wt% of AG, when compared to pure epoxy. Preliminary results on fracture toughness showed an enhancement of ~19% in K IC for AG/epoxy composites with 0.45 wt% of AG. Furthermore, our observations of fractured surfaces under scanning electron microscope gives evidence of pull-out of arms of AG tetrapod, interface and inter-graphite failure as the dominating mechanism for the toughness improvement in these composites. These observations were consistent with the results obtained from photoelasticity experiments on a thin film AG/epoxy model composite.« less

Screening of bacterial strains isolated from uranium mill tailings porewaters for bioremediation purposes.

PubMed

Sánchez-Castro, Iván; Amador-García, Ahinara; Moreno-Romero, Cristina; López-Fernández, Margarita; Phrommavanh, Vannapha; Nos, Jeremy; Descostes, Michael; Merroun, Mohamed L

2017-01-01

The present work characterizes at different levels a number of bacterial strains isolated from porewaters sampled in the vicinity of two French uranium tailing repositories. The 16S rRNA gene from 33 bacterial isolates, corresponding to the different morphotypes recovered, was almost fully sequenced. The resulting sequences belonged to 13 bacterial genera comprised in the phyla Firmicutes, Actinobacteria and Proteobacteria. Further characterization at physiological level and metals/metalloid tolerance provided evidences for an appropriate selection of bacterial strains potentially useful for immobilization of uranium and other common contaminants. By using High Resolution Transmission Electron Microscope (HRTEM), this potential ability to immobilize uranium as U phosphate mineral phases was confirmed for the bacterial strains Br3 and Br5 corresponding to Arthrobacter sp. and Microbacterium oxydans, respectively. Scanning Transmission Electron Microscope- High-Angle Annular Dark-Field (STEM-HAADF) analysis showed U accumulates on the surface and within bacterial cytoplasm, in addition to the extracellular space. Energy Dispersive X-ray (EDX) element-distribution maps demonstrated the presence of U and P within these accumulates. These results indicate the potential of certain bacterial strains isolated from porewaters of U mill tailings for immobilizing uranium, likely as uranium phosphates. Some of these bacterial isolates might be considered as promising candidates in the design of uranium bioremediation strategies. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

PubMed

Thennarasu, G; Kavithaa, S; Sivasamy, A

2011-08-01

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

Red shifts of the Eg(1) Raman mode of nanocrystalline TiO2:Er monoliths grown by sol-gel process

NASA Astrophysics Data System (ADS)

Palomino-Merino, R.; Trejo-Garcia, P.; Portillo-Moreno, O.; Jiménez-Sandoval, S.; Tomás, S. A.; Zelaya-Angel, O.; Lozada-Morales, R.; Castaño, V. M.

2015-08-01

Nanocrystalline monoliths of Er doped TiO2 were prepared by the sol-gel technique, by controlling the Er-doping levels into the TiO2 precursor solution. As-prepared and annealed in air samples showed the anatase TiO2 phase. The average diameter of the nanoparticles ranged from 19 to 2.6 nm as the nominal concentration of Er varies from 0% to 7%, as revealed by EDS analysis in an electron microscope. Photo Acoustic Spectroscopy (PAS) allowed calculate the forbidden band gap, evidencing an absorption edge at around 300 nm, attributed to TiO2 and evidence of electronic transitions or Er3+. The Raman spectra, corresponding to the anatase phase, show the main phonon mode Eg(1) band position at 144 cm-1 with a red shift for the annealing samples.

HRTEM low dose: the unfold of the morphed graphene, from amorphous carbon to morphed graphenes.

PubMed

Calderon, H A; Okonkwo, A; Estrada-Guel, I; Hadjiev, V G; Alvarez-Ramírez, F; Robles Hernández, F C

We present experimental evidence under low-dose conditions transmission electron microscopy for the unfolding of the evolving changes in carbon soot during mechanical milling. The milled soot shows evolving changes as a function of the milling severity or time. Those changes are responsible for the transformation from amorphous carbon to graphenes, graphitic carbon, and highly ordered structures such as morphed graphenes, namely Rh6 and Rh6-II. The morphed graphenes are corrugated layers of carbon with cross-linked covalently nature and sp 2 - or sp 3 -type allotropes. Electron microscopy and numerical simulations are excellent complementary tools to identify those phases. Furthermore, the TEAM 05 microscope is an outstanding tool to resolve the microstructure and prevent any damage to the sample. Other characterization techniques such as XRD, Raman, and XPS fade to convey a true identification of those phases because the samples are usually blends or mixes of the mentioned phases.

Differentiation between Prototheca and morphologically similar green algae in tissue.

PubMed

Chandler, F W; Kaplan, W; Callaway, C S

1978-07-01

Evidence that algae are pathogens was provided by the results of electron microscopic studies of tissues from five cattle and sheep suspected of having green algal infections. Chloroplasts were demonstrated in the algae in each case. Prototheca organisms, considered by some to be achloric mutants of green algae, are causative agents of disease in man and animals and may appear morphologically similar to green algae in tissue. However, electron microscopy showed that chloroplasts were absent in these organisms. Light microscopy revealed not only similarities in size, shape, and mode of reproduction, but also a striking difference between the Prototheca organisms and green algae. Unlike Prototheca, the green algae contained abundant cytoplasmic starch granules that were strongly positive by several staining procedures; these granules, which were PAS-negative following diastase digestion, provide a means of differentiating green algae from Prototheca cells in tissue.

Enhancement in surface area and magnetization of CoFe2O4 nanoparticles for targeted drug delivery application

NASA Astrophysics Data System (ADS)

Kale, Swati B.; Somvanshi, Sandeep B.; Sarnaik, M. N.; More, S. D.; Shukla, S. J.; Jadhav, K. M.

2018-05-01

This paper reports facile synthesis, characterizations by X-ray diffraction and scanning electron microscopy and magnetic behaviour of cobalt ferrite nanoparticles. Cobalt ferrite nanoparticles were prepared by sol-gel auto combustion technique using glycine as a fuel. Phase purity and nanocrystalline nature of the prepared sample was confirmed through X-ray diffraction technique. No extra peak other than cubic spinel structure was observed in the XRD pattern. The crystallite size calculated by using Scherrer's formula is of the order of 21.6 nm indicating the nanocrystalline nature of the prepared cobalt ferrite sample. The surface morphological studies were carried out using scanning electron microscope (SEM). SEM image shows homogeneous, agglomerated particles with sponge-like form. The saturation magnetization, coercivity and remenance magnetization obtained by hysteresis curve clearly gives the evidence of excellent and enhanced magnetic behaviour.

Electron Spin Relaxation: The Role of Spin-Orbit Coupling in Organic Semiconductors

NASA Astrophysics Data System (ADS)

Willis, M.; Nuccio, L.; Schulz, L.; Gillin, W.; Kreouzis, T.; Pratt, F.; Lord, J.; Heeney, M.; Fratini, S.; Bernhard, C.; Drew, A.

2012-02-01

Rapid development of organic materials has lead to their availability in commercial products. Until now, the spin degree of freedom has not generally been used in organic materials. As well as engineering difficulties, there are fundamental questions with respect to the electron spin relaxation (eSR) mechanisms in organic molecules. Muons used as a microscopic spin probe, localized to a single molecule, can access information needed to identify the relevant model for eSR. In this presentation I will introduce the ALC-MuSR technique describing how eSR can be extracted and the expected effects. I will show how the technique has been applied to small organic molecules such as the group III Quinolate series and functionalized molecules with a pentacene-like backbone. Lastly I will present the Z-number and temperature dependence in these organic molecules and show strong evidence for a spin-orbit based eSR mechanism.

Comments on ”Evidence of the hydrogen release mechanism in bulk MgH2”

NASA Astrophysics Data System (ADS)

Surrey, Alexander; Nielsch, Kornelius; Rellinghaus, Bernd

2017-04-01

The effect of an electron beam induced dehydrogenation of MgH2 in the transmission electron microscope (TEM) is largely underestimated by Nogita et al., and led the authors to a misinterpretation of their TEM observations. Firstly, the selected area diffraction (SAD) pattern is falsely interpreted. A re-evaluation of the SAD pattern reveals that no MgH2 is present in the sample, but that it rather consists of Mg and MgO only. Secondly, the transformation of the sample upon in-situ heating in the TEM cannot be ascribed to dehydrogenation, but is rather to be explained by the (nanoscale) Kirkendall effect, which leads to the formation of hollow MgO shells without any metallic Mg in their cores. Hence, the conclusions drawn from the TEM investigation are invalid, as the authors apparently have never studied MgH2.

Cultivation of pathogenic Treponema pallidum in vitro.

PubMed

Horváth, I; Duncan, W P; Bullard, J C

1981-01-01

Treponema pallidum was discovered relatively late and was not cultured in vitro. Both the delineation of T. pallidum biology and the eradication of syphilis suggest the necessity of cultivation in vitro. An attempt has been made with an improved medium to cultivate pathogenic T. pallidum Budapest strain in vitro. Only in the first passage, evidence of in vitro multiplication of T. pallidum has been established by (i) macroscopic observation, (ii) darkfield examination, (iii) electron microscopic examination, (iv) optical densities, (v) tritium labelled thymidine incorporation, and (vi) the pathogenicity off the cultured organisms was evidenced by rabbit challenge. Explanation of the oxygen utilization of T. pallidum suspension is discussed. Unidentified formations were observed on electron micrographs from the 96 h cultures. They may belong to the multiplication forms of treponemes. Further experiments are needed for their identification and for expansion of the multiplication of T. pallidum beyond the first passage.

A sensitive EUV Schwarzschild microscope for plasma studies with sub-micrometer resolution

DOE PAGES

Zastrau, U.; Rodel, C.; Nakatsutsumi, M.; ...

2018-02-05

We present an extreme ultraviolet (EUV) microscope using a Schwarzschild objective which is optimized for single-shot sub-micrometer imaging of laser-plasma targets. The microscope has been designed and constructed for imaging the scattering from an EUV-heated solid-density hydrogen jet. Here, imaging of a cryogenic hydrogen target was demonstrated using single pulses of the free-electron laser in Hamburg (FLASH) free-electron laser at a wavelength of 13.5 nm. In a single exposure, we observe a hydrogen jet with ice fragments with a spatial resolution in the sub-micrometer range. In situ EUV imaging is expected to enable novel experimental capabilities for warm dense mattermore » studies of micrometer-sized samples in laser-plasma experiments.« less

A sensitive EUV Schwarzschild microscope for plasma studies with sub-micrometer resolution

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

Zastrau, U.; Rodel, C.; Nakatsutsumi, M.

We present an extreme ultraviolet (EUV) microscope using a Schwarzschild objective which is optimized for single-shot sub-micrometer imaging of laser-plasma targets. The microscope has been designed and constructed for imaging the scattering from an EUV-heated solid-density hydrogen jet. Here, imaging of a cryogenic hydrogen target was demonstrated using single pulses of the free-electron laser in Hamburg (FLASH) free-electron laser at a wavelength of 13.5 nm. In a single exposure, we observe a hydrogen jet with ice fragments with a spatial resolution in the sub-micrometer range. In situ EUV imaging is expected to enable novel experimental capabilities for warm dense mattermore » studies of micrometer-sized samples in laser-plasma experiments.« less

Morphology-controllable of Sn doped ZnO nanorods prepared by spray pyrolysis for transparent electrode application

NASA Astrophysics Data System (ADS)

Hameed, M. Shahul; Princice, J. Joseph; Babu, N. Ramesh; Zahirullah, S. Syed; Deshmukh, Sampat G.; Arunachalam, A.

2018-05-01

Transparent conductive Sn doped ZnO nanorods have been deposited at various doping level by spray pyrolysis technique on glass substrate. The structural, surface morphological and optical properties of these films have been investigated with the help of X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM) and UV-Vis spectrophotometer respectively. XRD patterns revealed a successful high quality growth of single crystal ZnO nanorods with hexagonal wurtzite structure having (002) preferred orientation. The scanning electron microscope (SEM) image of the prepared films exposed the uniform distribution of Sn doped ZnO nanorod shaped grains. All these films were highly transparent in the visible region with average transmittance of 90%.

Development of micro-four-point probe in a scanning tunneling microscope for in situ electrical transport measurement.

PubMed

Ge, Jian-Feng; Liu, Zhi-Long; Gao, Chun-Lei; Qian, Dong; Liu, Canhua; Jia, Jin-Feng

2015-05-01

Electrons at surface may behave differently from those in bulk of a material. Multi-functional tools are essential in comprehensive studies on a crystal surface. Here, we developed an in situ microscopic four-point probe (4PP) transport measurement system on the basis of a scanning tunneling microscope (STM). In particular, convenient replacement between STM tips and micro-4PPs enables systematic investigations of surface morphology, electronic structure, and electrical transport property of a same sample surface. Performances of the instrument are demonstrated with high-quality STM images, tunneling spectra, and low-noise electrical I-V characteristic curves of a single-layer FeSe film grown on a conductive SrTiO3 surface.

Micromorphology of trichomes of Thymus malyi (Lamiaceae).

PubMed

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

2008-12-01

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

Fixation methods for electron microscopy of human and other liver

PubMed Central

Wisse, Eddie; Braet, Filip; Duimel, Hans; Vreuls, Celien; Koek, Ger; Olde Damink, Steven WM; van den Broek, Maartje AJ; De Geest, Bart; Dejong, Cees HC; Tateno, Chise; Frederik, Peter

2010-01-01

For an electron microscopic study of the liver, expertise and complicated, time-consuming processing of hepatic tissues and cells is needed. The interpretation of electron microscopy (EM) images requires knowledge of the liver fine structure and experience with the numerous artifacts in fixation, embedding, sectioning, contrast staining and microscopic imaging. Hence, the aim of this paper is to present a detailed summary of different methods for the preparation of hepatic cells and tissue, for the purpose of preserving long-standing expertise and to encourage new investigators and clinicians to include EM studies of liver cells and tissue in their projects. PMID:20556830

ELECTRON MICROSCOPIC OBSERVATIONS OF AMOEBA PROTEUS IN GROWTH AND INANITION

PubMed Central

Cohen, Adolph I.

1957-01-01

Electron microscopic observations have been made on growing and dividing specimens of Amoeba proteus and also on starving animals. Structures presumably corresponding to the mitochondria, alpha particles, vacuoles, and Golgi material are described. A new entity, designated as a foamy particle, is noted. Descriptions are given of the cytoplasmic and nuclear membranes. During division the inner, thick nuclear membrane component is seen to vanish and the outer membrane persist. Measurements suggest a gradual reappearance of the inner component with growth. Starving animals show a loss of cytoplasmic granularity and an increase in the electron density of mitochondria, presumably due to lipide accumulation. PMID:13481020

Electron microscopic observations of amoeba proteus in growth and inanition.

PubMed

COHEN, A I

1957-11-25

Electron microscopic observations have been made on growing and dividing specimens of Amoeba proteus and also on starving animals. Structures presumably corresponding to the mitochondria, alpha particles, vacuoles, and Golgi material are described. A new entity, designated as a foamy particle, is noted. Descriptions are given of the cytoplasmic and nuclear membranes. During division the inner, thick nuclear membrane component is seen to vanish and the outer membrane persist. Measurements suggest a gradual reappearance of the inner component with growth. Starving animals show a loss of cytoplasmic granularity and an increase in the electron density of mitochondria, presumably due to lipide accumulation.

Investigations in space-related molecular biology. [cryo-electron microscopic and diffraction studies on terrestrial and extraterrestrial specimens

NASA Technical Reports Server (NTRS)

Fernandez-Moran, H.; Pritzker, A. N.

1974-01-01

Improved instrumentation and preparation techniques for high resolution, high voltage cryo-electron microscopic and diffraction studies on terrestrial and extraterrestrial specimens are reported. Computer correlated ultrastructural and biochemical work on hydrated and dried cell membranes and related biological systems provided information on membrane organization, ice crystal formation and ordered water, RNA virus linked to cancer, lunar rock samples, and organometallic superconducting compounds. Apollo 11, 12, 14, and 15 specimens were analyzed

Collaborative Research and Development (CR&D). Delivery Order 0051: Atomic Scale Transmission Electron Microscope Image Modeling and Application to Semiconductor Heterointerface Characterization

DTIC Science & Technology

2008-01-01

information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD...microscopy ( AEM ), to characterize a variety of III-V semiconductor thin films. The materials investigated include superlattices based on the InAs- GaSb...technique. TEM observations were performed using a Philips-CM 200 FEG transmission electron microscope equipped with a field emission gun, operated at an

Diffusion length measurements using the scanning electron microscope. [in semiconductor devices

NASA Technical Reports Server (NTRS)

Weizer, V. G.

1975-01-01

A measurement technique employing the scanning electron microscope is described in which values of the true bulk diffusion length are obtained. It is shown that surface recombination effects can be eliminated through the application of highly doped surface field layers. The influence of high injection level effects and low-high junction current generation on the resulting measurement was investigated. Close agreement is found between the diffusion lengths measured by this method and those obtained using a penetrating radiation technique.

Local dynamic range compensation for scanning electron microscope imaging system.

PubMed

Sim, K S; Huang, Y H

2015-01-01

This is the extended project by introducing the modified dynamic range histogram modification (MDRHM) and is presented in this paper. This technique is used to enhance the scanning electron microscope (SEM) imaging system. By comparing with the conventional histogram modification compensators, this technique utilizes histogram profiling by extending the dynamic range of each tile of an image to the limit of 0-255 range while retains its histogram shape. The proposed technique yields better image compensation compared to conventional methods. © Wiley Periodicals, Inc.

DNA Binding Peptide Directed Synthesis of Continuous DNA Nanowires for Analysis of Large DNA Molecules by Scanning Electron Microscope.

PubMed

Kim, Kyung-Il; Lee, Seonghyun; Jin, Xuelin; Kim, Su Ji; Jo, Kyubong; Lee, Jung Heon

2017-01-01

Synthesis of smooth and continuous DNA nanowires, preserving the original structure of native DNA, and allowing its analysis by scanning electron microscope (SEM), is demonstrated. Gold nanoparticles densely assembled on the DNA backbone via thiol-tagged DNA binding peptides work as seeds for metallization of DNA. This method allows whole analysis of DNA molecules with entangled 3D features. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication and electric measurements of nanostructures inside transmission electron microscope.

PubMed

Chen, Qing; Peng, Lian-Mao

2011-06-01

Using manipulation holders specially designed for transmission electron microscope (TEM), nanostructures can be characterized, measured, modified and even fabricated in-situ. In-situ TEM techniques not only enable real-time study of structure-property relationships of materials at atomic scale, but also provide the ability to control and manipulate materials and structures at nanoscale. This review highlights in-situ electric measurements and in-situ fabrication and structure modification using manipulation holder inside TEM. Copyright © 2011 Elsevier B.V. All rights reserved.

Computer measurement of particle sizes in electron microscope images

NASA Technical Reports Server (NTRS)

Hall, E. L.; Thompson, W. B.; Varsi, G.; Gauldin, R.

1976-01-01

Computer image processing techniques have been applied to particle counting and sizing in electron microscope images. Distributions of particle sizes were computed for several images and compared to manually computed distributions. The results of these experiments indicate that automatic particle counting within a reasonable error and computer processing time is feasible. The significance of the results is that the tedious task of manually counting a large number of particles can be eliminated while still providing the scientist with accurate results.

Plasmon-mediated circularly polarized luminescence of GaAs in a scanning tunneling microscope

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

Mühlenberend, Svenja; Gruyters, Markus; Berndt, Richard, E-mail: berndt@physik.uni-kiel.de

2015-12-14

The electroluminescence from p-type GaAs(110) in a scanning tunneling microscope has been investigated at 6 K. Unexpectedly, high degrees of circular polarization have often been observed with ferromagnetic Ni tips and also with paramagnetic W and Ag tips. The data are interpreted in terms of two distinct excitation mechanisms. Electron injection generates intense luminescence with low polarization. Plasmon-mediated generation of electron-hole pairs leads to less intense emission, which, however, is highly polarized for many tips.

Hair follicle nevus occurring in frontonasal dysplasia: an electron microscopic observation.

PubMed

Kuwahara, H; Lao, L M; Kiyohara, T; Kumakiri, M; Igawa, H

2001-06-01

We report a rare hair follicle nevus that occurred in a three-month-old Japanese boy with mild frontonasal dysplasia. It had been present since birth. Histologically, numerous tiny vellus hair follicles were found within the dermis. The constituent cells of these follicles showed the features of follicular germ cells under the electron microscope. The fibroblasts around the follicles were active and merged with the colloid substance. Many myofibroblasts were found in a collagenous stroma in the atrophic lesion of the frontonasal dysplasia.

Tannic acid for smear layer removal: pilot study with scanning electron microscope.

PubMed

Bitter, N C

1989-04-01

The effects of a 25% tannic acid solution applied to the surface of prepared dentin was compared with untreated prepared dentin surfaces. The following results were demonstrated by electron microscope observation: (1) cavity preparations created an amorphous dentinal smear layer, (2) placement of a 25% tannic acid solution for 15 seconds removed the smear layer, (3) the contents of the dentinal tubules were not removed and no enlargement of dentinal tubules was found, and (3) a clean dentinal surface was observed.

Analytical electron microscopic studies and positron lifetime measurements in Al-doped MgO crystals

NASA Astrophysics Data System (ADS)

Pedrosa, M. A.; Pareja, R.; González, R.; Abraham, M. M.

1987-07-01

MgO crystals intentionally doped with Al were characterized by analytical electron microscopic examinations and positron lifetime measurements. Large spinel (MgO Al2O3) precipitates were observed in samples with high contents of Al. A well-defined crystallographic relationship between the precipitates and the matrix was found. The characteristics of positron lifetime spectra appear to depend on the valence state of the different impurities in the MgO lattice suggesting that positrons are trapped by vacancy impurity complexes.

Electronic structure and microscopic model of CoNb2O6

NASA Astrophysics Data System (ADS)

Molla, Kaimujjaman; Rahaman, Badiur

2018-05-01

We present the first principle density functional calculations to figure out the underlying spin model of CoNb2O6. The first principles calculations define the main paths of superexchange interaction between Co spins in this compound. We discuss the nature of the exchange paths and provide quantitative estimates of magnetic exchange couplings. A microscopic modeling based on analysis of the electronic structure of this system puts it in the interesting class of weakly couple geometrically frustrated isosceles triangular Ising antiferromagnet.

A simple way to obtain backscattered electron images in a scanning transmission electron microscope.

PubMed

Tsuruta, Hiroki; Tanaka, Shigeyasu; Tanji, Takayoshi; Morita, Chiaki

2014-08-01

We have fabricated a simple detector for backscattered electrons (BSEs) and incorporated the detector into a scanning transmission electron microscope (STEM) sample holder. Our detector was made from a 4-mm(2) Si chip. The fabrication procedure was easy, and similar to a standard transmission electron microscopy (TEM) sample thinning process based on ion milling. A TEM grid containing particle objects was fixed to the detector with a silver paste. Observations were carried out using samples of Au and latex particles at 75 and 200 kV. Such a detector provides an easy way to obtain BSE images in an STEM. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Microscopic description of orbital-selective spin ordering in BaMn2As2

NASA Astrophysics Data System (ADS)

Craco, L.; Carara, S. S.

2018-05-01

Using generalized gradient approximation+dynamical mean-field theory, we provide a microscopic description of orbital-selective spin ordering in the tetragonal manganese pnictide BaMn2As2 . We demonstrate the coexistence of local moments and small band-gap electronic states in the parent compound. We also explore the role played by electron/hole doping, showing that the Mott insulating state is rather robust to small removal of electron charge carriers similar to cuprate oxide superconductors. Good qualitative accord between theory and angle-resolved photoemission as well as electrical transport provides support to our view of orbital-selective spin ordering in BaMn2As2 . Our proposal is expected to be an important step to understanding the emergent correlated electronic structure of materials with persisting ordered localized moments coexisting with Coulomb reconstructed nonmagnetic electronic states.

Evidence from Opportunity's Microscopic Imager for water on Meridiani Planum.

PubMed

Herkenhoff, K E; Squyres, S W; Arvidson, R; Bass, D S; Bell, J F; Bertelsen, P; Ehlmann, B L; Farrand, W; Gaddis, L; Greeley, R; Grotzinger, J; Hayes, A G; Hviid, S F; Johnson, J R; Jolliff, B; Kinch, K M; Knoll, A H; Madsen, M B; Maki, J N; McLennan, S M; McSween, H Y; Ming, D W; Rice, J W; Richter, L; Sims, M; Smith, P H; Soderblom, L A; Spanovich, N; Sullivan, R; Thompson, S; Wdowiak, T; Weitz, C; Whelley, P

2004-12-03

The Microscopic Imager on the Opportunity rover analyzed textures of soils and rocks at Meridiani Planum at a scale of 31 micrometers per pixel. The uppermost millimeter of some soils is weakly cemented, whereas other soils show little evidence of cohesion. Rock outcrops are laminated on a millimeter scale; image mosaics of cross-stratification suggest that some sediments were deposited by flowing water. Vugs in some outcrop faces are probably molds formed by dissolution of relatively soluble minerals during diagenesis. Microscopic images support the hypothesis that hematite-rich spherules observed in outcrops and soils also formed diagenetically as concretions.

Mars Life? - Microscopic Egg-shaped Structures

NASA Technical Reports Server (NTRS)

1996-01-01

This electron microscope image shows egg-shaped structures, some of which may be possible microscopic fossils of Martian origin as discussed by NASA research published in the Aug. 16, 1996, issue of the journal Science. A two-year investigation found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils such as these inside of an ancient Martian rock that fell to Earth as a meteorite. The largest possible fossils are less than 1/100th the diameter of a human hair in size while most are ten times smaller.

The Scanning Optical Microscope: An Overview

NASA Astrophysics Data System (ADS)

Kino, G. S.; Corte, T. R.; Xiao, G. Q.

1988-07-01

In the last few years there has been a resurgence in research on optical microscopes. One reason stems from the invention of the acoustic microscope by Quate and Lemons,1 and the realization that some of the same principles could be applied to the optical microscope. The acoustic microscope has better transverse definition for the same wavelength than the standard optical microscope and at the same time has far better range definition. Consequently, Kompfner, who was involved with the work on the early acoustic microscope, decided to try out similar scanning microscope principles with optics, and started a group with Wilson and Sheppard to carry out such research at Oxford.2 Sometime earlier, Petran et a13 had invented the tandem scanning microscope which used many of the same principles. Now, in our laboratory at Stanford, these ideas on the tandem scanning microscope and the scanning optical microscope are converging. Another aspect of this work, which stems from the earlier experience with the acoustic microscope, involves measurement of both phase and amplitude of the optical beam. It is also possible to use scanned optical microscopy for other purposes. For instance, an optical beam can be used to excite electrons and holes in semiconductors, and the generated current can be measured. By scanning the optical beam over the semiconductor, an image can be obtained of the regions where there is strong or weak electron hole generation. This type of microscope is called OBIC (Optical Beam Induced Current). A second application involves fluorescent imaging of biological materials. Here we have the excellent range definition of a scanning optical microscope which eliminates unwanted glare from regions of the material where the beam is unfocused.3 A third application is focused on the heating effect of the light beam. With such a system, images can be obtained which are associated with changes in the thermal properties of a material, changes in recombination rates in semiconductors, and differences in material properties associated with either acoustic or thermal effects.4,5 Thus, the range of scanning optical microscopy applications is very large. In the main, the most important applications have been to semiconductors and to biology.

The Potential Protective Effects of 2-aminoethyl Diphenylborinate against Inner Ear Acoustic Trauma: Experimental Study Using Transmission and Scanning Electron Microscopy.

PubMed

Kaymakçı, Mustafa; Acar, Mustafa; Burukoglu, Dilek; Kutlu, Hatice Mehtap; Shojaolsadati, Paria; Cingi, Cemal; Bayar Muluk, Nuray

2015-04-01

In this prospective experimental study, we investigated the preventive effects of 2-aminoethyl diphenylborinate (2-APB) in rats exposed to acoustic trauma (AT). Light microscopic, transmission electron microscopic (TEM), and scanning electron microscopic (SEM) examinations were performed. Eighteen healthy Wistar albino rats were divided into the following three groups: groups 1 (control), 2 (AT), and 3 (AT+APB). The rats in groups 2 and 3 were exposed to AT; in group 3 rats, 2-APB at 2 mg/kg was also administered, initially transperitoneally, after 10 min. During the light microscopic, TEM, and SEM examinations, the structures of the cochlear hair cells, stereocilia, and Deiter's cells were normal in the control group. In the AT group, the organ of Corti and proximate structures were damaged according to the light microscopic examination. During the TEM examination, intense cellular damage and stereocilia loss were detected, while during the SEM examination, extensive damage and stereocilia loss were observed. Decreased damage with preserved cochlear structure was detected during the light microscopic examination in the AT+APB group than in the AT group. During the TEM and SEM examinations, although stereocilia loss occurred in the AT+APB group, near-normal cell, cilia, and tectorial membrane structures were also observed in the AT+APB group compared with the AT group. 2-APB may have protective effects against AT damage of the cochlea. The main mechanism underlying this effect is the inhibition of the vasoconstriction of the cochlear spiral modiolar artery, thereby improving cochlear blood flow. We conclude that 2-APB may also be effective if used immediately following AT.

Optimising electron microscopy experiment through electron optics simulation.

PubMed

Kubo, Y; Gatel, C; Snoeck, E; Houdellier, F

2017-04-01

We developed a new type of electron trajectories simulation inside a complete model of a modern transmission electron microscope (TEM). Our model incorporates the precise and real design of each element constituting a TEM, i.e. the field emission (FE) cathode, the extraction optic and acceleration stages of a 300kV cold field emission gun, the illumination lenses, the objective lens, the intermediate and projection lenses. Full trajectories can be computed using magnetically saturated or non-saturated round lenses, magnetic deflectors and even non-cylindrical symmetry elements like electrostatic biprism. This multi-scale model gathers nanometer size components (FE tip) with parts of meter length (illumination and projection systems). We demonstrate that non-trivial TEM experiments requiring specific and complex optical configurations can be simulated and optimized prior to any experiment using such model. We show that all the currents set in all optical elements of the simulated column can be implemented in the real column (I2TEM in CEMES) and used as starting alignment for the requested experiment. We argue that the combination of such complete electron trajectory simulations in the whole TEM column with automatic optimization of the microscope parameters for optimal experimental data (images, diffraction, spectra) allows drastically simplifying the implementation of complex experiments in TEM and will facilitate the development of advanced use of the electron microscope in the near future. Copyright © 2017 Elsevier B.V. All rights reserved.

Combined use of optical and electron microscopic techniques for the measurement of hygroscopic property, chemical composition, and morphology of individual aerosol particles.

PubMed

Ahn, Kang-Ho; Kim, Sun-Man; Jung, Hae-Jin; Lee, Mi-Jung; Eom, Hyo-Jin; Maskey, Shila; Ro, Chul-Un

2010-10-01

In this work, an analytical method for the characterization of the hygroscopic property, chemical composition, and morphology of individual aerosol particles is introduced. The method, which is based on the combined use of optical and electron microscopic techniques, is simple and easy to apply. An optical microscopic technique was used to perform the visual observation of the phase transformation and hygroscopic growth of aerosol particles on a single particle level. A quantitative energy-dispersive electron probe X-ray microanalysis, named low-Z particle EPMA, was used to perform a quantitative chemical speciation of the same individual particles after the measurement of the hygroscopic property. To validate the analytical methodology, the hygroscopic properties of artificially generated NaCl, KCl, (NH(4))(2)SO(4), and Na(2)SO(4) aerosol particles of micrometer size were investigated. The practical applicability of the analytical method for studying the hygroscopic property, chemical composition, and morphology of ambient aerosol particles is demonstrated.

[Observation by transmission electron microscope and identification of endophytic bacteria isolated from Bursaphelenchus xylophilus and B. mucronatus].

PubMed

Yuan, Weimin; Wu, Xiaoqin; Ye, Jianren; Tian, Xiaojing

2011-08-01

The pine wood nematode, Bursaphlenchus xylophilus, morphologically similar to B. mucronatus, is the pathogen of pine wilt disease. This study was focused on the endophytic bacteria present in these nematodes. Detailed observations were made on sections of all parts of the two types of nematodes by transmission electron microscope. The nematodes were surface-sterilized by soaking in 1% mercuric chloride and antibiotic mixture, and then ground and cultured on nutrient agar plate. The physiological and biochemical characteristics combined with molecular characterization of bacteria were analyzed and identified. Endophytic bacteria were found in intestines of the two nematodes by transmission electron microscope observations. On the basis of surface sterilization, total three bacteria strains were obtained from B. xylophilus and B. mucronatus. These bacteria belong to Stenotrophomonas and Ewingella. It confirms the presence of endophytic bacteria in Bursaphelenchus xylophilus and B. mucronatus and these bacteria may play a physical and ecological roles in nematodes.

Investigation of Microstructural Features Determining the Toughness of 980 MPa Bainitic Weld Metal

NASA Astrophysics Data System (ADS)

Cao, R.; Zhang, X. B.; Wang, Z.; Peng, Y.; Du, W. S.; Tian, Z. L.; Chen, J. H.

2014-02-01

The microstructural features that control the impact toughness of weld metals of a 980 MPa 8 pct Ni high-strength steel are investigated using instrumented Charpy V tester, optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), electron back-scattered diffraction (EBSD), and finite-element method (FEM) calculation. The results show that the critical event for cleavage fracture in this high-strength steel and weld metals is the propagation of a bainite packet-sized crack across the packet boundary into contiguous packets, and the bainitic packet sizes control the impact toughness. The high-angle misorientation boundaries detected in a bainite packet by EBSD form fine tear ridges on fracture surfaces. However, they are not the decisive factors controlling the cleavage fracture. The effects of Ni content are essential factors for improving the toughness. The extra large cleavage facets seriously deteriorate the toughness, which are formed on the interfaces of large columnar crystals growing in welding pools with high heat input.

Polarized light and scanning electron microscopic investigation of enamel hypoplasia in primary teeth.

PubMed

Sabel, Nina; Klingberg, Gunilla; Dietz, Wolfram; Nietzsche, Sandor; Norén, Jörgen G

2010-01-01

Enamel hypoplasia is a developmental disturbance during enamel formation, defined as a macroscopic defect in the enamel, with a reduction of the enamel thickness with rounded, smooth borders. Information on the microstructural level is still limited, therefore further studies are of importance to better understand the mechanisms behind enamel hypoplasia. To study enamel hypoplasia in primary teeth by means of polarized light microscopy and scanning electron microscopy. Nineteen primary teeth with enamel hypoplasia were examined in a polarized light microscope and in a scanning electron microscope. The cervical and incisal borders of the enamel hypoplasia had a rounded appearance, as the prisms in the rounded cervical area of the hypoplasia were bent. The rounded borders had a normal surface structure whereas the base of the defects appeared rough and porous. Morphological findings in this study indicate that the aetiological factor has a short duration and affects only certain ameloblasts. The bottom of the enamel hypoplasia is porous and constitutes possible pathways for bacteria into the dentin.

Synthesis and characterization of Ag@polycarbazole coaxial nanocables and their enhanced dispersion behavior

NASA Astrophysics Data System (ADS)

Zahoor, Ahmad; Teng, Qiu; Wang, Haiqiao; Choudhry, M. A.; Li, Xiaoyu

2011-06-01

Ag@polycarbazole coaxial nanocables (CNCs) have been successfully fabricated by the oxidative polymerization of carbazole over Ag nanowires (NWs) in acetonitrile. The morphology of Ag NWs and CNCs was studied by employing a transmission electron microscope (TEM) and a scanning electron microscope (SEM), which showed them to be a monodisperse material. The thickness of the polymer sheath was found to be 5 nm to 8 nm by observation under a high-resolution transmission electron microscope (HR-TEM). Energy dispersive X-ray spectroscopy (EDS), FT-IR and Raman measurements were used to characterize the polymer sheath, which demonstrated it to be a carbon material in polycarbazole form. X-ray photoelectron spectroscopy (XPS) was used for an interfacial study, which revealed that Ag surface atoms remained intact during polymer growth. In the end, zeta potential showed that the dispersion stability of Ag NWs increased due to polymer encapsulation, which is significant to obtain a particular alignment for anisotropic measurement of electrical conductivity.

Sb,123121 nuclear quadrupole resonance as a microscopic probe in the Te-doped correlated semimetal FeSb2: Emergence of electronic Griffith phase, magnetism, and metallic behavior

NASA Astrophysics Data System (ADS)

Gippius, A. A.; Zhurenko, S. V.; Hu, R.; Petrovic, C.; Baenitz, M.

2018-02-01

Sb,123121 nuclear quadrupole resonance (NQR) was applied to Fe(Sb1-xTex)2 in the low doping regime (x =0 , 0.01, and 0.05) as a microscopic zero field probe to study the evolution of 3 d magnetism and the emergence of metallic behavior. Whereas the NQR spectra itself reflects the degree of local disorder via the width of the individual NQR lines, the spin lattice relaxation rate (SLRR) 1 /T1(T ) probes the fluctuations at the Sb site. The fluctuations originate either from conduction electrons or from magnetic moments. In contrast to the semimetal FeSb2 with a clear signature of the charge and spin gap formation in 1 /T1(T ) T [˜exp/(Δ kBT ) ] , the 1% Te-doped system exhibits almost metallic conductivity and the SLRR nicely confirms that the gap is almost filled. A weak divergence of the SLRR coefficient 1 /T1(T ) T ˜T-n˜T-0.2 points towards the presence of electronic correlations towards low temperatures. This is supported by the electronic specific heat coefficient γ =(Cel/T ) showing a power-law divergence γ (T ) ˜T-m˜(1/T1T ) 1 /2˜T-n /2˜Cel/T which is expected in the renormalized Landau Fermi liquid theory for correlated electrons. In contrast to that the 5% Te-doped sample exhibits a much larger divergence in the SLRR coefficient showing 1 /T1(T ) T ˜T-0.72 . According to the specific heat divergence a power law with n =2 m =0.56 is expected for the SLRR. This dissimilarity originates from admixed critical magnetic fluctuations in the vicinity of antiferromagnetic long range order with 1 /T1(T ) T ˜T-3 /4 behavior. Furthermore Te-doped FeSb2 as a disordered paramagnetic metal might be a platform for the electronic Griffith phase scenario. NQR evidences a substantial asymmetric broadening of the Sb,123121 NQR spectrum for the 5% sample. This has a predominant electronic origin in agreement with the electronic Griffith phase and stems probably from an enhanced Sb-Te bond polarization and electronic density shift towards the Te atom inside Sb-Te dumbbell.

Sb 121 , 123 nuclear quadrupole resonance as a microscopic probe in the Te-doped correlated semimetal FeSb 2 : Emergence of electronic Griffith phase, magnetism, and metallic behavior

DOE PAGES

Gippius, A. A.; Zhurenko, S. V.; Hu, R.; ...

2018-02-12

121,123Sb nuclear quadrupole resonance (NQR) was applied to Fe(Sb 1-xTe x) 2 in the low doping regime (x = 0 , 0.01, and 0.05) as a microscopic zero field probe to study the evolution of 3d magnetism and the emergence of metallic behavior. Whereas the NQR spectra itself reflects the degree of local disorder via the width of the individual NQR lines, the spin lattice relaxation rate (SLRR) 1/T 1 (T) probes the fluctuations at the Sb site. The fluctuations originate either from conduction electrons or from magnetic moments. In contrast to the semimetal FeSb 2 with a clear signaturemore » of the charge and spin gap formation in 1/T 1(T)T[~exp/(Δk BT)] , the 1% Te-doped system exhibits almost metallic conductivity and the SLRR nicely confirms that the gap is almost filled. A weak divergence of the SLRR coefficient 1/T 1(T)T ~ T -n ~ T -0.2 points towards the presence of electronic correlations towards low temperatures. This is supported by the electronic specific heat coefficient γ = (C el/T) showing a power-law divergence γ (T) ~ T -m ~ (1/T 1T) 1/2 ~ T -n/2 ~ C el/T which is expected in the renormalized Landau Fermi liquid theory for correlated electrons. In contrast to that the 5% Te-doped sample exhibits a much larger divergence in the SLRR coefficient showing 1/T 1(T)T ~ T -0.72 . According to the specific heat divergence a power law with n = 2 m = 0.56 is expected for the SLRR. This dissimilarity originates from admixed critical magnetic fluctuations in the vicinity of antiferromagnetic long range order with 1/T 1(T)T ~ T -3/4 behavior. Furthermore Te-doped FeSb 2 as a disordered paramagnetic metal might be a platform for the electronic Griffith phase scenario. NQR evidences a substantial asymmetric broadening of the 121,123Sb NQR spectrum for the 5% sample. Lastly, this has a predominant electronic origin in agreement with the electronic Griffith phase and stems probably from an enhanced Sb-Te bond polarization and electronic density shift towards the Te atom inside Sb-Te dumbbell.« less

Sb 121 , 123 nuclear quadrupole resonance as a microscopic probe in the Te-doped correlated semimetal FeSb 2 : Emergence of electronic Griffith phase, magnetism, and metallic behavior

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

Gippius, A. A.; Zhurenko, S. V.; Hu, R.

121,123Sb nuclear quadrupole resonance (NQR) was applied to Fe(Sb 1-xTe x) 2 in the low doping regime (x = 0 , 0.01, and 0.05) as a microscopic zero field probe to study the evolution of 3d magnetism and the emergence of metallic behavior. Whereas the NQR spectra itself reflects the degree of local disorder via the width of the individual NQR lines, the spin lattice relaxation rate (SLRR) 1/T 1 (T) probes the fluctuations at the Sb site. The fluctuations originate either from conduction electrons or from magnetic moments. In contrast to the semimetal FeSb 2 with a clear signaturemore » of the charge and spin gap formation in 1/T 1(T)T[~exp/(Δk BT)] , the 1% Te-doped system exhibits almost metallic conductivity and the SLRR nicely confirms that the gap is almost filled. A weak divergence of the SLRR coefficient 1/T 1(T)T ~ T -n ~ T -0.2 points towards the presence of electronic correlations towards low temperatures. This is supported by the electronic specific heat coefficient γ = (C el/T) showing a power-law divergence γ (T) ~ T -m ~ (1/T 1T) 1/2 ~ T -n/2 ~ C el/T which is expected in the renormalized Landau Fermi liquid theory for correlated electrons. In contrast to that the 5% Te-doped sample exhibits a much larger divergence in the SLRR coefficient showing 1/T 1(T)T ~ T -0.72 . According to the specific heat divergence a power law with n = 2 m = 0.56 is expected for the SLRR. This dissimilarity originates from admixed critical magnetic fluctuations in the vicinity of antiferromagnetic long range order with 1/T 1(T)T ~ T -3/4 behavior. Furthermore Te-doped FeSb 2 as a disordered paramagnetic metal might be a platform for the electronic Griffith phase scenario. NQR evidences a substantial asymmetric broadening of the 121,123Sb NQR spectrum for the 5% sample. Lastly, this has a predominant electronic origin in agreement with the electronic Griffith phase and stems probably from an enhanced Sb-Te bond polarization and electronic density shift towards the Te atom inside Sb-Te dumbbell.« less

New trend in electron holography

NASA Astrophysics Data System (ADS)

Tanigaki, Toshiaki; Harada, Ken; Murakami, Yasukazu; Niitsu, Kodai; Akashi, Tetsuya; Takahashi, Yoshio; Sugawara, Akira; Shindo, Daisuke

2016-06-01

Electron holography using a coherent electron wave is a promising technique for high-resolution visualization of electromagnetic fields in and around objects. The capability of electron holography has been enhanced by the development of new technologies and has thus become an even more powerful tool for exploring scientific frontiers. This review introduces these technologies including split-illumination electron holography and vector-field electron tomography. Split-illumination electron holography, which uses separated coherent waves, overcomes the limits imposed by the lateral coherence requirement for electron waves in electron holography. Areas that are difficult to observe using conventional electron holography are now observable. Exemplified applications include observing a singular magnetic domain wall in electrical steel sheets, local magnetizations at anti-phase boundaries, and electrostatic potentials in metal-oxide-semiconductor field-effect transistors. Vector-field electron tomography can be used to visualize magnetic vectors in three dimensions. Two components of the vectors are reconstructed using dual-axis tomography, and the remaining one is calculated using div B   =  0. A high-voltage electron microscope can be used to achieve precise magnetic reconstruction. For example, magnetic vortices have been visualized using a 1 MV holography electron microscope.

Extreme ultraviolet patterned mask inspection performance of advanced projection electron microscope system for 11nm half-pitch generation

NASA Astrophysics Data System (ADS)

Hirano, Ryoichi; Iida, Susumu; Amano, Tsuyoshi; Watanabe, Hidehiro; Hatakeyama, Masahiro; Murakami, Takeshi; Suematsu, Kenichi; Terao, Kenji

2016-03-01

Novel projection electron microscope optics have been developed and integrated into a new inspection system named EBEYE-V30 ("Model EBEYE" is an EBARA's model code) , and the resulting system shows promise for application to half-pitch (hp) 16-nm node extreme ultraviolet lithography (EUVL) patterned mask inspection. To improve the system's inspection throughput for 11-nm hp generation defect detection, a new electron-sensitive area image sensor with a high-speed data processing unit, a bright and stable electron source, and an image capture area deflector that operates simultaneously with the mask scanning motion have been developed. A learning system has been used for the mask inspection tool to meet the requirements of hp 11-nm node EUV patterned mask inspection. Defects are identified by the projection electron microscope system using the "defectivity" from the characteristics of the acquired image. The learning system has been developed to reduce the labor and costs associated with adjustment of the detection capability to cope with newly-defined mask defects. We describe the integration of the developed elements into the inspection tool and the verification of the designed specification. We have also verified the effectiveness of the learning system, which shows enhanced detection capability for the hp 11-nm node.

Contributed review: Review of integrated correlative light and electron microscopy.

PubMed

Timmermans, F J; Otto, C

2015-01-01

New developments in the field of microscopy enable to acquire increasing amounts of information from large sample areas and at an increased resolution. Depending on the nature of the technique, the information may reveal morphological, structural, chemical, and still other sample characteristics. In research fields, such as cell biology and materials science, there is an increasing demand to correlate these individual levels of information and in this way to obtain a better understanding of sample preparation and specific sample properties. To address this need, integrated systems were developed that combine nanometer resolution electron microscopes with optical microscopes, which produce chemically or label specific information through spectroscopy. The complementary information from electron microscopy and light microscopy presents an opportunity to investigate a broad range of sample properties in a correlated fashion. An important part of correlating the differences in information lies in bridging the different resolution and image contrast features. The trend to analyse samples using multiple correlated microscopes has resulted in a new research field. Current research is focused, for instance, on (a) the investigation of samples with nanometer scale distribution of inorganic and organic materials, (b) live cell analysis combined with electron microscopy, and (c) in situ spectroscopic and electron microscopy analysis of catalytic materials, but more areas will benefit from integrated correlative microscopy.

21 CFR 1000.15 - Examples of electronic products subject to the Radiation Control for Health and Safety Act of 1968.

Code of Federal Regulations, 2012 CFR

2012-04-01

.... (a) Examples of electronic products which may emit x-rays and other ionizing electromagnetic radiation, electrons, neutrons, and other particulate radiation include: Ionizing electromagnetic radiation... radiation and ionizing electromagnetic radiation: Electron microscopes. Neutron generators. (b) Examples of...

21 CFR 1000.15 - Examples of electronic products subject to the Radiation Control for Health and Safety Act of 1968.

Code of Federal Regulations, 2010 CFR

2010-04-01

.... (a) Examples of electronic products which may emit x-rays and other ionizing electromagnetic radiation, electrons, neutrons, and other particulate radiation include: Ionizing electromagnetic radiation... radiation and ionizing electromagnetic radiation: Electron microscopes. Neutron generators. (b) Examples of...

21 CFR 1000.15 - Examples of electronic products subject to the Radiation Control for Health and Safety Act of 1968.

Code of Federal Regulations, 2011 CFR

2011-04-01

.... (a) Examples of electronic products which may emit x-rays and other ionizing electromagnetic radiation, electrons, neutrons, and other particulate radiation include: Ionizing electromagnetic radiation... radiation and ionizing electromagnetic radiation: Electron microscopes. Neutron generators. (b) Examples of...

21 CFR 1000.15 - Examples of electronic products subject to the Radiation Control for Health and Safety Act of 1968.

Code of Federal Regulations, 2014 CFR

2014-04-01

.... (a) Examples of electronic products which may emit x-rays and other ionizing electromagnetic radiation, electrons, neutrons, and other particulate radiation include: Ionizing electromagnetic radiation... radiation and ionizing electromagnetic radiation: Electron microscopes. Neutron generators. (b) Examples of...

21 CFR 1000.15 - Examples of electronic products subject to the Radiation Control for Health and Safety Act of 1968.

Code of Federal Regulations, 2013 CFR

2013-04-01

.... (a) Examples of electronic products which may emit x-rays and other ionizing electromagnetic radiation, electrons, neutrons, and other particulate radiation include: Ionizing electromagnetic radiation... radiation and ionizing electromagnetic radiation: Electron microscopes. Neutron generators. (b) Examples of...

Microscopy and microanalysis of complex nanosized strengthening precipitates in new generation commercial Al-Cu-Li alloys.

PubMed

Guinel, M J-F; Brodusch, N; Sha, G; Shandiz, M A; Demers, H; Trudeau, M; Ringer, S P; Gauvin, R

2014-09-01

Precipitates (ppts) in new generation aluminum-lithium alloys (AA2099 and AA2199) were characterised using scanning and transmission electron microscopy and atom probe tomography. Results obtained on the following ppts are reported: Guinier-Preston zones, T1 (Al2 CuLi), β' (Al3 Zr) and δ' (Al3 Li). The focus was placed on their composition and the presence of minor elements. X-ray energy-dispersive spectrometry in the electron microscopes and mass spectrometry in the atom probe microscope showed that T1 ppts were enriched in zinc (Zn) and magnesium up to about 1.9 and 3.5 at.%, respectively. A concentration of 2.5 at.% Zn in the δ' ppts was also measured. Unlike Li and copper, Zn in the T1 ppts could not be detected using electron energy-loss spectroscopy in the transmission electron microscope because of its too low concentration and the small sizes of these ppts. Indeed, Monte Carlo simulations of EEL spectra for the Zn L2,3 edge showed that the signal-to-noise ratio was not high enough and that the detection limit was at least 2.5 at.%, depending on the probe current. Also, the simulation of X-ray spectra confirmed that the detection limit was exceeded for the Zn Kα X-ray line because the signal-to-noise ratio was high enough in that case, which is in agreement with our observations. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

Asbestos Testing: Is the EPA Misleading You?

ERIC Educational Resources Information Center

Levins, Hoag

1983-01-01

Experts warn that only electron microscopes can see the smaller fibers of asbestos that are known to cause the most cancers, though the Environmental Protection Agency still endorses optical microscopes for asbestos removal verification. Asbestos testing methods are explained and sources of information are provided. (MLF)

Confocal laser scanning microscopic photoconversion: a new method to stabilize fluorescently labeled cellular elements for electron microscopic analysis.

PubMed

Colello, Raymond J; Tozer, Jordan; Henderson, Scott C

2012-01-01

Photoconversion, the method by which a fluorescent dye is transformed into a stable, osmiophilic product that can be visualized by electron microscopy, is the most widely used method to enable the ultrastructural analysis of fluorescently labeled cellular structures. Nevertheless, the conventional method of photoconversion using widefield fluorescence microscopy requires long reaction times and results in low-resolution cell targeting. Accordingly, we have developed a photoconversion method that ameliorates these limitations by adapting confocal laser scanning microscopy to the procedure. We have found that this method greatly reduces photoconversion times, as compared to conventional wide field microscopy. Moreover, region-of-interest scanning capabilities of a confocal microscope facilitate the targeting of the photoconversion process to individual cellular or subcellular elements within a fluorescent field. This reduces the area of the cell exposed to light energy, thereby reducing the ultrastructural damage common to this process when widefield microscopes are employed. © 2012 by John Wiley & Sons, Inc.

Electronic structure, dielectric response, and surface charge distribution of RGD (1FUV) peptide.

PubMed

Adhikari, Puja; Wen, Amy M; French, Roger H; Parsegian, V Adrian; Steinmetz, Nicole F; Podgornik, Rudolf; Ching, Wai-Yim

2014-07-08

Long and short range molecular interactions govern molecular recognition and self-assembly of biological macromolecules. Microscopic parameters in the theories of these molecular interactions are either phenomenological or need to be calculated within a microscopic theory. We report a unified methodology for the ab initio quantum mechanical (QM) calculation that yields all the microscopic parameters, namely the partial charges as well as the frequency-dependent dielectric response function, that can then be taken as input for macroscopic theories of electrostatic, polar, and van der Waals-London dispersion intermolecular forces. We apply this methodology to obtain the electronic structure of the cyclic tripeptide RGD-4C (1FUV). This ab initio unified methodology yields the relevant parameters entering the long range interactions of biological macromolecules, providing accurate data for the partial charge distribution and the frequency-dependent dielectric response function of this peptide. These microscopic parameters determine the range and strength of the intricate intermolecular interactions between potential docking sites of the RGD-4C ligand and its integrin receptor.

76 FR 58245 - Application(s) for Duty-Free Entry of Scientific Instruments

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-20

... Laboratory, 480 Cornell Avenue, Upton, New York 11973. Instrument: Electron Microscope. Manufacturer: JEOL... of energy-related matter including superconductors and thermoelectric materials, using electron...

Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope.

PubMed

Bäcke, Olof; Lindqvist, Camilla; de Zerio Mendaza, Amaia Diaz; Gustafsson, Stefan; Wang, Ergang; Andersson, Mats R; Müller, Christian; Kristiansen, Per Magnus; Olsson, Eva

2017-05-01

We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices. To investigate how electron irradiation affects the thermal stability of polymer:fullerene films, a model bulk-heterojunction film based on a thiophene-quinoxaline copolymer and a fullerene derivative was heat-treated in-situ in a transmission electron microscope. In areas of the film that exposed to the electron beam the nanostructure of the film remained stable, while the nanostructure in areas not exposed to the electron beam underwent large phase separation and nucleation of fullerene crystals. UV-vis spectroscopy shows that the polymer:fullerene films are stable for electron doses up to 2000kGy. Copyright © 2016 Elsevier B.V. All rights reserved.

Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope.

PubMed

Bäcke, Olof; Lindqvist, Camilla; de Zerio Mendaza, Amaia Diaz; Gustafsson, Stefan; Wang, Ergang; Andersson, Mats R; Müller, Christian; Kristiansen, Per Magnus; Olsson, Eva

2017-02-01

We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices. To investigate how electron irradiation affects the thermal stability of polymer:fullerene films, a model bulk-heterojunction film based on a thiophene-quinoxaline copolymer and a fullerene derivative was heat-treated in-situ in a transmission electron microscope. In areas of the film that exposed to the electron beam the nanostructure of the film remained stable, while the nanostructure in areas not exposed to the electron beam underwent large phase separation and nucleation of fullerene crystals. UV-vis spectroscopy shows that the polymer:fullerene films are stable for electron doses up to 2000kGy. Copyright © 2017 Elsevier B.V. All rights reserved.

Electronic and structural aspects of spin transitions observed by optical microscopy. The case of [Fe(ptz)6](BF4)2.

PubMed

Chong, Christian; Mishra, Haritosh; Boukheddaden, Kamel; Denise, Stéphane; Bouchez, Guillaume; Collet, Eric; Ameline, Jean-Claude; Naik, Anil D; Garcia, Yann; Varret, François

2010-02-11

The colorimetric analysis of images recorded with an optical microscope during the onset of the spin crossover transformation allows monitoring separately the involved electronic and structural aspects, through the separation of resonant absorption and scattering effects. Complementary information can also be obtained by using the polarized modes of the microscope. These potentialities are illustrated by the observation of [Fe(ptz)(6)](BF(4))(2) single crystals during the onset of the thermal transitions in the 110-140 K range. We characterized the interplay between the electronic (HS <--> LS) and structural (order <--> disorder) transformations. Elastic stresses and mechanical effects (hopping, self-cleavage) generated by the volume change upon electronic transition are also illustrated, with their impact on the photoswitching properties of the crystals.

Correlative Fluorescence and Electron Microscopy in 3D-Scanning Electron Microscope Perspective.

PubMed

Franks, Jonathan; Wallace, Callen T; Shibata, Masateru; Suga, Mitsuo; Erdman, Natasha; Stolz, Donna B; Watkins, Simon C

2017-04-03

The ability to correlate fluorescence microscopy (FM) and electron microscopy (EM) data obtained on biological (cell and tissue) specimens is essential to bridge the resolution gap between the data obtained by these different imaging techniques. In the past such correlations were limited to either EM navigation in two dimensions to the locations previously highlighted by fluorescence markers, or subsequent high-resolution acquisition of tomographic information using a TEM. We present a novel approach whereby a sample previously investigated by FM is embedded and subjected to sequential mechanical polishing and backscatter imaging by scanning electron microscope. The resulting three dimensional EM tomogram of the sample can be directly correlated to the FM data. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

The temperature-dependency of the optical band gap of ZnO measured by electron energy-loss spectroscopy in a scanning transmission electron microscope

NASA Astrophysics Data System (ADS)

Granerød, Cecilie S.; Galeckas, Augustinas; Johansen, Klaus Magnus; Vines, Lasse; Prytz, Øystein

2018-04-01

The optical band gap of ZnO has been measured as a function of temperature using Electron Energy-Loss Spectroscopy (EELS) in a (Scanning) Transmission Electron Microscope ((S)TEM) from approximately 100 K up towards 1000 K. The band gap narrowing shows a close to linear dependency for temperatures above 250 K and is accurately described by Varshni, Bose-Einstein, Pässler and Manoogian-Woolley models. Additionally, the measured band gap is compared with both optical absorption measurements and photoluminescence data. STEM-EELS is here shown to be a viable technique to measure optical band gaps at elevated temperatures, with an available temperature range up to 1500 K and the benefit of superior spatial resolution.

What transmission electron microscopes can visualize now and in the future.

PubMed

Müller, Shirley A; Aebi, Ueli; Engel, Andreas

2008-09-01

Our review concentrates on the progress made in high-resolution transmission electron microscopy (TEM) in the past decade. This includes significant improvements in sample preparation by quick-freezing aimed at preserving the specimen in a close-to-native state in the high vacuum of the microscope. Following advances in cold stage and TEM vacuum technology systems, the observation of native, frozen hydrated specimens has become a widely used approach. It fostered the development of computer guided, fully automated low-dose data acquisition systems allowing matched pairs of images and diffraction patterns to be recorded for electron crystallography, and the collection of entire tilt-series for electron tomography. To achieve optimal information transfer to atomic resolution, field emission electron guns combined with acceleration voltages of 200-300 kV are now routinely used. The outcome of these advances is illustrated by the atomic structure of mammalian aquaporin-O and by the pore-forming bacterial cytotoxin ClyA resolved to 12 A. Further, the Yersinia injectisome needle, a bacterial pseudopilus and the binding of phalloidin to muscle actin filaments were chosen to document the advantage of the high contrast offered by dedicated scanning transmission electron microscopy (STEM) and/or the STEM's ability to measure the mass of protein complexes and directly link this to their shape. Continued progress emerging from leading research laboratories and microscope manufacturers will eventually enable us to determine the proteome of a single cell by electron tomography, and to more routinely solve the atomic structure of membrane proteins by electron crystallography.

x-y-recording in transmission electron microscopy. A versatile and inexpensive interface to personal computers with application to stereology.

PubMed

Rickmann, M; Siklós, L; Joó, F; Wolff, J R

1990-09-01

An interface for IBM XT/AT-compatible computers is described which has been designed to read the actual specimen stage position of electron microscopes. The complete system consists of (i) optical incremental encoders attached to the x- and y-stage drivers of the microscope, (ii) two keypads for operator input, (iii) an interface card fitted to the bus of the personal computer, (iv) a standard configuration IBM XT (or compatible) personal computer optionally equipped with a (v) HP Graphic Language controllable colour plotter. The small size of the encoders and their connection to the stage drivers by simple ribbed belts allows an easy adaptation of the system to most electron microscopes. Operation of the interface card itself is supported by any high-level language available for personal computers. By the modular concept of these languages, the system can be customized to various applications, and no computer expertise is needed for actual operation. The present configuration offers an inexpensive attachment, which covers a wide range of applications from a simple notebook to high-resolution (200-nm) mapping of tissue. Since section coordinates can be processed in real-time, stereological estimations can be derived directly "on microscope". This is exemplified by an application in which particle numbers were determined by the disector method.

Application of Environmental Scanning Electron Microscope-Nanomanipulation System on Spheroplast Yeast Cells Surface Observation.

PubMed

Rad, Maryam Alsadat; Ahmad, Mohd Ridzuan; Nakajima, Masahiro; Kojima, Seiji; Homma, Michio; Fukuda, Toshio

2017-01-01

The preparation and observations of spheroplast W303 cells are described with Environmental Scanning Electron Microscope (ESEM). The spheroplasting conversion was successfully confirmed qualitatively, by the evaluation of the morphological change between the normal W303 cells and the spheroplast W303 cells, and quantitatively, by determining the spheroplast conversion percentage based on the OD 800 absorbance data. From the optical microscope observations as expected, the normal cells had an oval shape whereas spheroplast cells resemble a spherical shape. This was also confirmed under four different mediums, that is, yeast peptone-dextrose (YPD), sterile water, sorbitol-EDTA-sodium citrate buffer (SCE), and sorbitol-Tris-Hcl-CaCl 2 (CaS). It was also observed that the SCE and CaS mediums had a higher number of spheroplast cells as compared to the YPD and sterile water mediums. The OD 800 absorbance data also showed that the whole W303 cells were fully converted to the spheroplast cells after about 15 minutes. The observations of the normal and the spheroplast W303 cells were then performed under an environmental scanning electron microscope (ESEM). The normal cells showed a smooth cell surface whereas the spheroplast cells had a bleb-like surface after the loss of its integrity when removing the cell wall.

Frequency-doubled Alexandrite laser for use in periodontology: a scanning electron microscopic investigation

NASA Astrophysics Data System (ADS)

Rechmann, Peter; Hennig, Thomas

1996-12-01

During prior studies it could be demonstrated that engaging a frequency double Alexandrite-laser allows a fast and strictly selective ablation of supra- and subgingival calculus. Furthermore, the removal of unstained microbial plaque was observed. First conclusions were drawn following light microscopic investigations on undecalcified sections of irradiated teeth. In the present study the cementum surface after irradiation with a frequency doubled Alexandrite-laser was observed by means of a scanning electron microscope. After irradiation sections of teeth were dried in alcohol and sputtered with gold. In comparison irradiated cementum surfaces of unerupted operatively removed wisdom teeth and tooth surfaces after the selective removal of calculus were investigated. A complete removal of calculus was observed as well as a remaining smooth surface of irradiated cementum.

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

PubMed Central

Iancu, Violeta; Hla, Saw-Wai

2006-01-01

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

The objective lens of the electron microscope with correction of spherical and axial chromatic aberrations.

PubMed

Bimurzaev, S B; Aldiyarov, N U; Yakushev, E M

2017-10-01

The paper describes the principle of operation of a relatively simple aberration corrector for the transmission electron microscope objective lens. The electron-optical system of the aberration corrector consists of the two main elements: an electrostatic mirror with rotational symmetry and a magnetic deflector formed by the round-shaped magnetic poles. The corrector operation is demonstrated by calculations on the example of correction of basic aberrations of the well-known objective lens with a bell-shaped distribution of the axial magnetic field. Two of the simplest versions of the corrector are considered: a corrector with a two-electrode electrostatic mirror and a corrector with a three-electrode electrostatic mirror. It is shown that using the two-electrode mirror one can eliminate either spherical or chromatic aberration of the objective lens, without changing the value of its linear magnification. Using a three-electrode mirror, it is possible to eliminate spherical and chromatic aberrations of the objective lens simultaneously, which is especially important in designing electron microscopes with extremely high resolution. © The Author 2017. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A Hydrodynamic Theory for Spatially Inhomogeneous Semiconductor Lasers: Microscopic Approach

NASA Technical Reports Server (NTRS)

Li, Jianzhong; Ning, C. Z.; Biegel, Bryan A. (Technical Monitor)

2001-01-01

Starting from the microscopic semiconductor Bloch equations (SBEs) including the Boltzmann transport terms in the distribution function equations for electrons and holes, we derived a closed set of diffusion equations for carrier densities and temperatures with self-consistent coupling to Maxwell's equation and to an effective optical polarization equation. The coherent many-body effects are included within the screened Hartree-Fock approximation, while scatterings are treated within the second Born approximation including both the in- and out-scatterings. Microscopic expressions for electron-hole (e-h) and carrier-LO (c-LO) phonon scatterings are directly used to derive the momentum and energy relaxation rates. These rates expressed as functions of temperatures and densities lead to microscopic expressions for self- and mutual-diffusion coefficients in the coupled density-temperature diffusion equations. Approximations for reducing the general two-component description of the electron-hole plasma (EHP) to a single-component one are discussed. In particular, we show that a special single-component reduction is possible when e-h scattering dominates over c-LO phonon scattering. The ambipolar diffusion approximation is also discussed and we show that the ambipolar diffusion coefficients are independent of e-h scattering, even though the diffusion coefficients of individual components depend sensitively on the e-h scattering rates. Our discussions lead to new perspectives into the roles played in the single-component reduction by the electron-hole correlation in momentum space induced by scatterings and the electron-hole correlation in real space via internal static electrical field. Finally, the theory is completed by coupling the diffusion equations to the lattice temperature equation and to the effective optical polarization which in turn couples to the laser field.

Simulating electron wave dynamics in graphene superlattices exploiting parallel processing advantages

NASA Astrophysics Data System (ADS)

Rodrigues, Manuel J.; Fernandes, David E.; Silveirinha, Mário G.; Falcão, Gabriel

2018-01-01

This work introduces a parallel computing framework to characterize the propagation of electron waves in graphene-based nanostructures. The electron wave dynamics is modeled using both "microscopic" and effective medium formalisms and the numerical solution of the two-dimensional massless Dirac equation is determined using a Finite-Difference Time-Domain scheme. The propagation of electron waves in graphene superlattices with localized scattering centers is studied, and the role of the symmetry of the microscopic potential in the electron velocity is discussed. The computational methodologies target the parallel capabilities of heterogeneous multi-core CPU and multi-GPU environments and are built with the OpenCL parallel programming framework which provides a portable, vendor agnostic and high throughput-performance solution. The proposed heterogeneous multi-GPU implementation achieves speedup ratios up to 75x when compared to multi-thread and multi-core CPU execution, reducing simulation times from several hours to a couple of minutes.

Electron-excited energy dispersive x-ray spectrometry in the variable pressure scanning electron microscope (EDS/VPSEM): it's not microanalysis anymore!

NASA Astrophysics Data System (ADS)

Newbury, Dale E.; Ritchie, Nicholas W. M.

2015-10-01

X-ray spectra suffer significantly degraded spatial resolution when measured in the variable-pressure scanning electron microscope (VPSEM, chamber pressure 1 Pa to 2500 Pa) as compared to highvacuum SEM (operating pressure < 10 mPa). Depending on the gas path length, electrons that are scattered hundreds of micrometers outside the focused beam can contribute 90% or more of the measured spectrum. Monte Carlo electron trajectory simulation, available in NIST DTSA-II, models the gas scattering and simulates mixed composition targets, e.g., particle on substrate. The impact of gas scattering at the major (C > 0.1 mass fraction), minor (0.01 <= C <= 0.1), and trace (C < 0.01) constituent levels can be estimated. NIST DTSA-II for Java-platforms is available free at: http://www.cstl.nist.gov/div837/837.02/epq/dtsa2/index.html).

Use of reciprocal lattice layer spacing in electron backscatter diffraction pattern analysis

PubMed

Michael; Eades

2000-03-01

In the scanning electron microscope using electron backscattered diffraction, it is possible to measure the spacing of the layers in the reciprocal lattice. These values are of great use in confirming the identification of phases. The technique derives the layer spacing from the higher-order Laue zone rings which appear in patterns from many materials. The method adapts results from convergent-beam electron diffraction in the transmission electron microscope. For many materials the measured layer spacing compares well with the calculated layer spacing. A noted exception is for higher atomic number materials. In these cases an extrapolation procedure is described that requires layer spacing measurements at a range of accelerating voltages. This procedure is shown to improve the accuracy of the technique significantly. The application of layer spacing measurements in EBSD is shown to be of use for the analysis of two polytypes of SiC.

Direct in situ observation of the electron-driven synthesis of Ag filaments on α-Ag2WO4 crystals

PubMed Central

Longo, E.; Cavalcante, L. S.; Volanti, D. P.; Gouveia, A. F.; Longo, V. M.; Varela, J. A.; Orlandi, M. O.; Andrés, J.

2013-01-01

In this letter, we report, for the first time, the real-time in situ nucleation and growth of Ag filaments on α-Ag2WO4 crystals driven by an accelerated electron beam from an electronic microscope under high vacuum. We employed several techniques to characterise the material in depth. By using these techniques combined with first-principles modelling based on density functional theory, a mechanism for the Ag filament formation followed by a subsequent growth process from the nano- to micro-scale was proposed. In general, we have shown that an accelerated electron beam from an electronic microscope under high vacuum enables in situ visualisation of Ag filaments with subnanometer resolution and offers great potential for addressing many fundamental issues in materials science, chemistry, physics and other fields of science. PMID:23591807

In-line three-dimensional holography of nanocrystalline objects at atomic resolution

PubMed Central

Chen, F.-R.; Van Dyck, D.; Kisielowski, C.

2016-01-01

Resolution and sensitivity of the latest generation aberration-corrected transmission electron microscopes allow the vast majority of single atoms to be imaged with sub-Ångstrom resolution and their locations determined in an image plane with a precision that exceeds the 1.9-pm wavelength of 300 kV electrons. Such unprecedented performance allows expansion of electron microscopic investigations with atomic resolution into the third dimension. Here we report a general tomographic method to recover the three-dimensional shape of a crystalline particle from high-resolution images of a single projection without the need for sample rotation. The method is compatible with low dose rate electron microscopy, which improves on signal quality, while minimizing electron beam-induced structure modifications even for small particles or surfaces. We apply it to germanium, gold and magnesium oxide particles, and achieve a depth resolution of 1–2 Å, which is smaller than inter-atomic distances. PMID:26887849

Direct observation of electronic-liquid-crystal phase transitions and their microscopic origin in La 1/3Ca 2/3MnO 3

DOE PAGES

Tao, J.; Sun, K.; Yin, W. -G.; ...

2016-11-22

The ground-state electronic order in doped manganites is frequently associated with a lattice modulation, contributing to their many interesting properties. However, measuring the thermal evolution of the lattice superstructure with reciprocal-space probes alone can lead to ambiguous results with competing interpretations. Here, we provide direct observations of the evolution of the superstructure in La 1/3Ca 2/3MnO 3 in real space, as well as reciprocal space, using transmission electron microscopic (TEM) techniques. We show that the transitions are the consequence of a proliferation of dislocations plus electronic phase separation. The resulting states are well described by the symmetries associated with electronic-liquid-crystalmore » (ELC) phases. Furthermore, our results resolve the long-standing controversy over the origin of the incommensurate superstructure and suggest a new structural model that is consistent with recent theoretical calculations.« less

An historical account of the development and applications of the negative staining technique to the electron microscopy of viruses.

PubMed

Horne, R W; Wildy, P

1979-09-01

A brief historical account of the development and applications of the negative staining techniques to the study of the structure of viruses and their components as observed in the electron microscope is presented. Although the basic method of surrounding or embedding specimens in opaque dyes was used in light microscopy dating from about 1884, the equivalent preparative techniques applied to electron microscopy were comparatively recent. The combination of experiments on a sophisticated bacterial virus and the installation of a high resolution electron microscope in the Cavendish Laboratory, Cambridge, during 1954, subsequently led to the analysis of several important morphological features of animal, plant and bacterial viruses. The implications of the results from these early experiments on viruses and recent developments in negative staining methods for high resolution image analysis of electron micrographs are also discussed.

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

PubMed

Gutierrez-Urrutia, Ivan

2017-01-01

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

Effective Pb2+ removal from water using nanozerovalent iron stored 10 months

NASA Astrophysics Data System (ADS)

Ahmed, M. A.; Bishay, Samiha T.; Ahmed, Fatma M.; El-Dek, S. I.

2017-10-01

Heavy metal removal from water required reliable and cost-effective considerations, fast separation as well as easy methodology. In this piece of research, nanozerovalent iron (NZVI) was prepared as ideal sorbent for Pb2+ removal. The sample was characterized using X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and atomic force microscope (AFM-SPM). Batch experiments comprised the effect of pH value and contact time on the adsorption process. The same NZVI was stored for a shelf time (10 months) and the batch experiment was repeated. The outcomes of the investigation assured that NZVI publicized an extraordinary large metal uptake (98%) after a short contact time (10 h). The stored sample revealed the same effectiveness on Pb2+ removal under the same conditions. The results of the physical properties, magnetic susceptibility, and conductance were correlated with the adsorption efficiency. This work offers evidence that these NZVI particles could be potential candidate for Pb2+ removal in large scale, stored for a long time using a simple, green, and cost-effective methodology, and represent an actual feedback in waste water treatment.

Time Resolved Microscopy of Charge Trapping in Polycrystalline Pentacene

NASA Astrophysics Data System (ADS)

Jaquith, Michael; Muller, Erik; Marohn, John

2007-03-01

The microscopic mechanisms by which charges trap in organic electronic materials are poorly understood. Muller and Marohn recently showed that electric force microscopy (EFM) can be used to image trapped charge in working pentacene thin-film transistors [E. M. Muller et al., Adv. Mater. 17 1410 (2005)]. We have made a new discovery by imaging trapped charge in pentacene films with much larger grains. In contrast to the previous study in which charge was found to trap inhomogeneously throughout the transistor gap, we find microscopic evidence for a new trapping mechanism in which charges trap predominantly at the pentacene/metal interface in large-grained devices. We conclude that at least two charge trapping mechanisms are at play in polycrystalline pentacene. We have made localized measurements of the trap growth over time by performing pulsed-gate EFM experiments. Trap formation is not instantaneous, taking up to a second to complete. Furthermore, the charge-trapping rate depends strongly on gate voltage (or hole concentration). This kinetics data is consistent with the hypothesis that traps form by chemical reaction.

MORPH-II, a software package for the analysis of scanning-electron-micrograph images for the assessment of the fractal dimension of exposed stone surfaces

USGS Publications Warehouse

Mossotti, Victor G.; Eldeeb, A. Raouf

2000-01-01

Turcotte, 1997, and Barton and La Pointe, 1995, have identified many potential uses for the fractal dimension in physicochemical models of surface properties. The image-analysis program described in this report is an extension of the program set MORPH-I (Mossotti and others, 1998), which provided the fractal analysis of electron-microscope images of pore profiles (Mossotti and Eldeeb, 1992). MORPH-II, an integration of the modified kernel of the program MORPH-I with image calibration and editing facilities, was designed to measure the fractal dimension of the exposed surfaces of stone specimens as imaged in cross section in an electron microscope.

The Wavelength-Dispersive Spectrometer and Its Proposed Use in the Analytical Electron Microscope

NASA Technical Reports Server (NTRS)

Goldstein, Joseph I.; Lyman, Charles E.; Williams, David B.

1989-01-01

The Analytical Electron Microscope (AEM) equipped with a wavelength-dispersive spectrometer (WDS) should have the ability to resolve peaks which normally overlap in the spectra from an energy-dispersive spectrometer (EDS). With a WDS it should also be possible to measure lower concentrations of elements in thin foils due to the increased peak-to-background ratio compared with EDS. The WDS will measure X-ray from the light elements (4 less than Z less than 1O) more effectively. This paper addresses the possibility of interfacing a compact WDS with a focussing circle of approximately 4 cm to a modem AEM with a high-brightness (field emission) source of electrons.

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

NASA Technical Reports Server (NTRS)

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.

Evolution of ferromagnetism in two-dimensional electron gas of LaTiO3/SrTiO3

NASA Astrophysics Data System (ADS)

Wen, Fangdi; Cao, Yanwei; Liu, Xiaoran; Pal, B.; Middey, S.; Kareev, M.; Chakhalian, J.

2018-03-01

Understanding, creating, and manipulating spin polarization of two-dimensional electron gases at complex oxide interfaces present an experimental challenge. For example, despite almost a decade long research effort, the microscopic origin of ferromagnetism in LaAlO3/SrTiO3 heterojunctions is still an open question. Here, by using a prototypical two-dimensional electron gas (2DEG) which emerges at the interface between band insulator SrTiO3 and antiferromagnetic Mott insulator LaTiO3, the experiment reveals the evidence for magnetic phase separation in a hole-doped Ti d1 t2g system, resulting in spin-polarized 2DEG. The details of electronic and magnetic properties of the 2DEG were investigated by temperature-dependent d.c. transport, angle-dependent X-ray photoemission spectroscopy, and temperature-dependent magnetoresistance. The observation of clear hysteresis in magnetotransport at low magnetic fields implies spin-polarization from magnetic islands in the hole rich LaTiO3 near the interface. These findings emphasize the role of magnetic instabilities in doped Mott insulators, thus providing another path for designing all-oxide structures relevant to spintronic applications.

Growth and nanomechanical characterization of nanoscale 3D architectures grown via focused electron beam induced deposition

DOE PAGES

Lewis, Brett B.; Mound, Brittnee A.; Srijanto, Bernadeta; ...

2017-10-12

Here, nanomechanical measurements of platinum–carbon 3D nanoscale architectures grown via focused electron beam induced deposition (FEBID) were performed using a nanoindentation system in a scanning electron microscope (SEM) for simultaneous in situ imaging.

National Plant Diagnostic Network, Taxonomic training videos: Aphids under the microscope - Cerataphis brasiliensis

USDA-ARS?s Scientific Manuscript database

Training is a critical part of aphid (Hemiptera: Aphididae) identification. This video provides provides training to identify the palm aphid, Cerataphis brasiliensis, using a compound microscope and an electronic identification key called “LUCID.” The video demonstrates key morphological structures...

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

PubMed

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

2018-04-01

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

Backscattered electron SEM imaging of resin sections from plant specimens: observation of histological to subcellular structure and CLEM.

PubMed

Rizzo, N W; Duncan, K E; Bourett, T M; Howard, R J

2016-08-01

We have refined methods for biological specimen preparation and low-voltage backscattered electron imaging in the scanning electron microscope that allow for observation at continuous magnifications of ca. 130-70 000 X, and documentation of tissue and subcellular ultrastructure detail. The technique, based upon early work by Ogura & Hasegawa (1980), affords use of significantly larger sections from fixed and resin-embedded specimens than is possible with transmission electron microscopy while providing similar data. After microtomy, the sections, typically ca. 750 nm thick, were dried onto the surface of glass or silicon wafer and stained with heavy metals-the use of grids avoided. The glass/wafer support was then mounted onto standard scanning electron microscopy sample stubs, carbon-coated and imaged directly at an accelerating voltage of 5 kV, using either a yttrium aluminum garnet or ExB backscattered electron detector. Alternatively, the sections could be viewed first by light microscopy, for example to document signal from a fluorescent protein, and then by scanning electron microscopy to provide correlative light/electron microscope (CLEM) data. These methods provide unobstructed access to ultrastructure in the spatial context of a section ca. 7 × 10 mm in size, significantly larger than the typical 0.2 × 0.3 mm section used for conventional transmission electron microscopy imaging. Application of this approach was especially useful when the biology of interest was rare or difficult to find, e.g. a particular cell type, developmental stage, large organ, the interface between cells of interacting organisms, when contextual information within a large tissue was obligatory, or combinations of these factors. In addition, the methods were easily adapted for immunolocalizations. © 2015 The Author. Journal of Microscopy published by John Wiley & Sons, Ltd on behalf of the Royal Microscopical Society.

Mars Life? - Microscopic Structures

NASA Technical Reports Server (NTRS)

1996-01-01

In the center of this electron microscope image of a small chip from a meteorite are several tiny structures that are possible microscopic fossils of primitive, bacteria-like organisms that may have lived on Mars more than 3.6 billion years ago. A two-year investigation by a NASA research team found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils such as these inside of an ancient Martian rock that fell to Earth as a meteorite. The largest possible fossils are less than 1/100th the diameter of a human hair in size while most are ten times smaller.

Structural, electronic structure and antibacterial properties of graphene-oxide nano-sheets

NASA Astrophysics Data System (ADS)

Sharma, Aditya; Varshney, Mayora; Nanda, Sitansu Sekhar; Shin, Hyun Joon; Kim, Namdong; Yi, Dong Kee; Chae, Keun-Hwa; Ok Won, Sung

2018-04-01

Correlation between the structural/electronic structure properties and bio-activity of graphene-based materials need to be thoroughly evaluated before their commercial implementation in the health and environment precincts. To better investigate the local hybridization of sp2/sp3 orbitals of the functional groups of graphene-oxide (GO) and their execution in the antimicrobial mechanism, we exemplify the antibacterial activity of GO sheets towards the Escherichia coli bacteria (E. coli) by applying the field-emission scanning electron microscopy (FESEM), near edge X-ray absorption fine structure (NEXAFS) and scanning transmission X-ray microscope (STXM) techniques. C K-edge and O K-edge NEXAFS spectra have revealed lesser sp2 carbon atoms in the aromatic ring and attachment of functional oxygen groups at GO sheets. Entrapment of E. coli bacteria by GO sheets is evidenced by FESEM investigations and has also been corroborated by nano-scale imaging of bacteria using the STXM. Spectroscopy evidence of functional oxygen moieties with GO sheets and physiochemical entrapment of E. coli bacteria have assisted us to elaborate the mechanism of cellular oxidative stress-induced disruption of bacterial membrane.

High-resolution electron microscopic evidence for the filamentous structure of the cyst wall in Giardia muris and Giardia duodenalis.

PubMed

Erlandsen, S L; Bemrick, W J; Pawley, J

1989-10-01

High-resolution morphological studies of the cyst wall of Giardia spp. were performed using low-voltage scanning electron microscopy (LVSEM) and transmission electron microscopy (TEM). The cyst wall was composed of membranous and filamentous layers. The membranous layer consisted of an inner and an outer cyst membrane separated by a thin layer of cytoplasm. The filamentous layer contained individual filaments that ranged from 7 to 20 nm in diameter when measured by LVSEM, formed a dense meshwork with branches or interconnections, and were occasionally arranged on the surface in whorled patterns. Cysts of Giardia muris from mice, Giardia duodenalis from dogs, pigs, voles, beavers, muskrats, and humans, and Giardia psittaci from a bird (parakeet), possessed an essentially identical wall composed of filaments. Inducement of excystation in viable Giardia cysts produced a dramatic increase in the interfilament spacing over an entire cyst, but none was observed in heat-killed or chemically fixed control cysts. These results demonstrated that the cyst wall of Giardia spp. was composed of a complex arrangement of filaments, presumably formed during the process of encystment.

Electron Microscopic Observations of Rabbit Antibodies.

PubMed

Hall, C E; Nisonoff, A; Slayter, H S

1959-12-01

Electron micrographs were obtained showing the individual, shadow-cast macromolecules from solutions of purified anti-p-azobenzoate rabbit antibody and of normal gamma-globulin. The two materials look alike and consist mainly of asymmetrical rod-like particles about 30 to 40 A in diameter. Lengths are not constant but the weight average is about 250 A for the antibodies and about 200 A for the gamma-globulin. The average observed dimensions are reasonably consistent with values deduced from physical-chemical methods, although the shape is more nearly that of a cylindrical rod rather than the ellipsoid employed in hydrodynamical theory. Mixtures of antibody and specific dihaptenic dye were examined in attempts to establish the mode of the specific aggregation. At the high dilutions necessary for electron microscopy (0.1 mg./ml.), the effect of the dye was small and tended to be masked by non-specific aggregation on drying. The evidence suggests that under these conditions the specific reaction involves an end-to-end aggregation of the elementary particles to produce a weight average length about twice that of the pure antibody.

Visible light-harvesting of TiO2 nanotubes array by pulsed laser deposited CdS

NASA Astrophysics Data System (ADS)

Bjelajac, Andjelika; Djokic, Veljko; Petrovic, Rada; Socol, Gabiel; Mihailescu, Ion N.; Florea, Ileana; Ersen, Ovidiu; Janackovic, Djordje

2014-08-01

Titanium dioxide (TiO2) nanotubes arrays, obtained by anodization technique and annealing, were decorated with CdS using pulsed laser deposition method. Their structural, morphological and chemical characterization was carried out by electron microscopy in scanning (SEM) and transmission (TEM) modes, combined with energy dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS). It was demonstrated that the quantity of deposited CdS can be controlled by varying the number of laser pulses. The chemical mapping of the elements of interest was performed using the energy filtered mode of the electron microscope. The results showed that pulse laser deposition is an adequate technique for deposition of CdS inside and between 100 nm wide TiO2 nanotubes. The diffuse reflectance spectroscopy investigation of selected samples proved that the absorption edge of the prepared CdS/TiO2 nanocomposites is significantly extended to the visible range. The corresponding band gaps were determinated from the Tauc plot of transformed Kubelka-Munk function. The band gap reduction of TiO2 nanotubes by pulsed laser deposition of CdS was put in evidence.

Effect of linear alkyl benzene sulfonate in skin of fish fingerlings (Cirrhina mrigala): observations with scanning electron microscope

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

Misra, V.; Chawla, G.; Kumar, V.

1987-04-01

Pathomorphological changes in the skin was noticed under the scanning electron microscope in fish fingerlings (Cirrhina mrigala) exposed to 0.005 ppm (25% of the LC50) concentration to linear alkyl benzene sulfonate. The epithelial cells present in the epidermis of the skin were found to secrete more mucus with linear alkyl benzene sulfonate (LAS) than did controls. The presence or deposition of mucus on the surface of skin indicated likely molecular interaction between constituents of mucus and LAS.

Environmental scanning electron microscopy of personal and household products.

PubMed

Hoyberg, K

1997-03-01

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

Morphological observation and characterization of the Pseudoregma bambucicola with the scanning electron microscope.

PubMed

Nong, Xiang; Zeng, Xuemei; Yang, Yaojun; Liang, Zi; Tang, Mei; Liao, Lejuan; Luo, Chaobing

2017-11-01

Both leica microscopic camera system and scanning electron microscopy was used to observe and characterize the feet, back, abdomen, antennae and mouthparts of the Pseudoregma bambucicola from the bamboo, Bambusa multiplex . The possible functions of all the external morphological characteristics of the P. bambucicola were described and discussed in detail, which offers a basis for further enriching the biology, phylogeny and ecological niche of the P. bambucicola . Moreover, the morphological results should contribute to morphological identification and differentiation of the P. bambucicola from other aphids in the same family.

Electron microscopic and optical studies of prism faces of synthetic quartz

NASA Technical Reports Server (NTRS)

Buzek, B. C.; Vagh, A. S.

1977-01-01

Application of electron and optical microscopic techniques to the study of growth spirals on quartz crystal faces is described. Attention is centered on the centers of the spirals and on screw ledges; overhanging kinks are revealed on one side of the spiral centers. The possibility that these special features may have developed after growth of the crystals went to completion is explored. The conjecture is raised that such structures might result from adsorption of growth-inhibiting impurities at the center of the growth spiral on the quartz habit faces.

Characteristics of different frequency ranges in scanning electron microscope images

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

Sim, K. S., E-mail: kssim@mmu.edu.my; Nia, M. E.; Tan, T. L.

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.

Electron microscope detection of an endogenous infection of retrovirus-like particles in L20B cells.

PubMed

Roberts, Jason A; Thorley, Bruce R; Bruggink, Leesa D; Marshall, John A

2013-08-01

L20B cells are a cell line commonly used for the isolation of poliovirus. The current study indicates that L20B cells are chronically infected with a retrovirus-like particle that replicates in the cytoplasm and buds through the plasma membrane. The findings indicate that care is needed in the use of L20B cells for certain virus isolation studies and emphasize the importance of electron microscope studies as an adjunct to the development of diagnostic virology protocols.

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

PubMed Central

2014-01-01

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

Ballistic-Electron-Emission Microscope

NASA Technical Reports Server (NTRS)

Kaiser, William J.; Bell, L. Douglas

1990-01-01

Ballistic-electron-emission microscope (BEEM) employs scanning tunneling-microscopy (STM) methods for nondestructive, direct electrical investigation of buried interfaces, such as interface between semiconductor and thin metal film. In BEEM, there are at least three electrodes: emitting tip, biasing electrode, and collecting electrode, receiving current crossing interface under investigation. Signal-processing device amplifies electrode signals and converts them into form usable by computer. Produces spatial images of surface by scanning tip; in addition, provides high-resolution images of buried interface under investigation. Spectroscopic information extracted by measuring collecting-electrode current as function of one of interelectrode voltages.