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Sample records for electron microscopic investigations

  1. Investigation of diesel ash particulate matter: A scanning electron microscope and transmission electron microscope study

    NASA Astrophysics Data System (ADS)

    Liati, A.; Dimopoulos Eggenschwiler, P.; Müller Gubler, E.; Schreiber, D.; Aguirre, M.

    2012-03-01

    Investigation of ash PM deposited in a diesel particulate filter (DPF) operating on a light truck by means of SEM and TEM reveals the following: ash inside the DPF occurs in form of chemically very inhomogeneous, mostly brittle agglomerates accumulated at the plugged ends of inlet channels and deposited directly on the inlet channel walls all along the filter length. Ash agglomerates occur within pores of the channel walls. A minor part of ash PM may escape to the atmosphere. The individual ash phases are mostly crystalline with round outlines and sizes between ca. 170 and 60 nm, down to 7-12 nm, that is far below the breathable size range PM10. Aggregation of the predominantly finest fraction of ash particles leads to densification, which may translate to fewer breakouts from the DPF. EDX mapping and chemical analyses of the bulk ash reveal that ash consists mainly of Ca, Mg, P, Zn, S, O and minor Fe, Al and Si. Based on TEM diffraction data of ash single phases, combined with data on their chemistry, the diversity of ash phases is higher than previously presumed. Comparison with the ash particles of a heavily used DPF from a passenger car operating with Fe-based fuel-borne additives reveals characteristics very similar to those found for the light truck DPF with a tendency to generally lower sizes of the participating phases, mostly between 30 and 60 nm. 4-40 nm large, locally abundant Pt particles deriving from the coating material of the diesel oxidation catalyst (DOC) upstream the DPF occur within ash agglomerates of both DPFs. Ash collected from the exhaust gas at the exit of the light truck DPF under normal engine operation reveals that some fine particles, as well as a few of the larger (200-600 nm) ash-bearing agglomerates escape filtration. Very fine ash particles are reaching the atmosphere also attached onto soot agglomerates.

  2. TEAM Electron Microscope Animation

    SciTech Connect

    2012-01-01

    The TEAM Electron Microscope, a device that enables atomic-scale imaging in 3-D, has a rotating stage that can hold and position samples inside electron microscopes with unprecedented stability, position-control accuracy, and range of motion.The TEAM Stage makes one of the world's most powerful electron microscopes even better, and enables previously impossible experiments.

  3. 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

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

    NASA Astrophysics Data System (ADS)

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

    2005-10-01

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

  5. Investigation of Sterilization Effect by various Gas Plasmas and Electron Microscopic Observation of Bacteria

    NASA Astrophysics Data System (ADS)

    Sasaki, Yota; Takamatsu, Toshihiro; Uehara, Kodai; Oshita, Takaya; Miyahara, Hidekazu; Okino, Akitoshi; Ikeda, Keiko; Matsumura, Yuriko; Iwasawa, Atsuo; Kohno, Masahiro

    2014-10-01

    Atmospheric non-thermal plasmas have attracted attention as a new sterilization method. It is considered that factor of plasma sterilization are mainly reactive oxygen species (ROS). However, the sterilization mechanism hasn't been investigated in detail because conventional plasma sources have a limitation in usable gas species and lack variety of ROS. So we developed multi-gas plasma jet which can generate various gas plasmas. In this study, investigation of sterilization effect by various gas plasmas and electron microscopic observation of bacteria were performed. Oxygen, nitrogen, carbon dioxide, argon and air were used as plasma gas. To investigate gas-species dependence of sterilization effect, S.aureus was treated. As a result, nitrogen plasma and carbon dioxide plasma were effective for sterilization. To investigate sterilization mechanism, the surface of S.aureus was observed by scanning electron microscope. As a result, dimples were observed on the surface after irradiation of nitrogen plasma, but no change observed in the case of carbon dioxide plasma. These results suggest that bactericidal mechanism of nitrogen and carbon dioxide plasma should be different. In the presentation, Measurement result of ROS will be reported.

  6. Forensic Scanning Electron Microscope

    NASA Astrophysics Data System (ADS)

    Keeley, R. H.

    1983-03-01

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

  7. Light and scanning electron microscopic investigations on MiteStop-treated poultry red mites.

    PubMed

    Locher, Nina; Klimpel, Sven; Abdel-Ghaffar, Fathy; Al Rasheid, Khaled A S; Mehlhorn, Heinz

    2010-07-01

    Recent studies of the neem seed product MiteStop showed that it has a good acaricidal effect against all developmental stages of the poultry red mite, Dermanyssus gallinae. In vitro tests proved an efficacy at direct contact, as well as by fumigant toxicity. Light and scanning electron microscopic (SEM) investigations showed no clear, morphologically visible signs of an effect caused by fumigant toxicity. Direct contact with the neem product, however, seemed to be of great impact. Chicken mites turned dark brown or even black after being treated with the neem product. SEM analysis showed damages along the body surface of the mites.

  8. 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.

  9. Neurohistochemical and electron microscopic investigations of pathological and age-related changes in the cardiovascular system.

    PubMed

    Shvalev, V N; Guski, H; Fernández-Britto, J E; Sosunov, A A; Pavlovich, E R; Anikin AYu; Zhuchkova, N I; Kargina-Terentyeva, R A

    1992-01-01

    Neurohistochemical and electron microscopic investigations of the autonomic nervous system (ANS) of man and animals suggest that its ontogenesis can be divided into the premediatory, mediatory and postmediatory periods of development. The postmediatory period begins heterochronically in various ganglia of the ANS. A normal process of early cardiac desympathization usually occurs at the age of 35 to 60 years. Specific changes of preceding sudden cardiac death are elicited in different parts of the ANS and adrenal glands. This is accompanied by focal myocardial desympathization. Coronary vessels and conducting system which may influence myocardial hypersensitivity zones to catecholamines are involved in the process of destabilization of the cardiac function. Moreover, relationships are demonstrated which exist between the atherosclerotic lesions of the aortic wall and the status of its nerve plexuses.

  10. Nanosecond electron microscopes

    PubMed

    Bostanjoglo; Elschner; Mao; Nink; Weingartner

    2000-04-01

    Combining electron optics, fast electronics and pulsed lasers, a transmission and a photoelectron emission microscope were built, which visualize events in thin films and on surfaces with a time resolution of several nanoseconds. The high-speed electron microscopy is capable to track fast laser-induced processes in metals below the ablation threshold, which are difficult to detect by other imaging techniques. The material response to nano- and femtosecond laser pulses was found to be very different. It was dominated by thermo/chemocapillary flow and chemical reactions in the case of nanosecond pulses, and by mechanical deformations and non-thermal electron emission after a femtosecond pulse.

  11. Electron microscope studies

    SciTech Connect

    Crewe, A.V.; Kapp, O.H.

    1992-07-01

    This is a report covering the research performed in the Crewe laboratory between 1964 and 1992. Because of limitations of space we have provided relatively brief summaries of the major research directions of the facility during these years. A complete bibliography has been included and we have referenced groups of pertinent publications at the beginning of each section. This report summarizes our efforts to develop better electron microscopes and chronicles many of the experimental programs, in materials science and biology, that acted both as a stimulus to better microscope design and also as a testing ground for many instrumental innovations.

  12. Ultra-structural hair alterations of drug abusers: a scanning electron microscopic investigation

    PubMed Central

    Turkmenoglu, Fatma Pinar; Kasirga, Ugur Baran; Celik, Hakan Hamdi

    2015-01-01

    As drug abuse carries a societal stigma, patients do not often report their history of drug abuse to the healthcare providers. However, drug abuse is highly co-morbid with a host of other health problems such as psychiatric disorders and skin diseases, and majority of individuals with drug use disorders seek treatment in the first place for other problems. Therefore, it is very important for physicians to be aware of clinical signs and symptoms of drug use. Recently diagnostic value of dermatologic tissue alterations associated with drug abuse has become a very particular interest because skin changes were reported to be the earliest noticeable consequence of drug abuse prompting earlier intervention and treatment. Although hair is an annex of skin, alterations on hair structure due to drug use have not been demonstrated. This study represents the first report on ultra-structural hair alterations of drug abusers. We have investigated ultra-structure of the hair samples obtained from 6 cocaine, 6 heroin, 7 cannabis and 4 lysergic acid diethylamide (LSD) abusers by scanning electron microscope (SEM). SEM analysis of hair samples gave us drug-specific discriminating alterations. We suggest that results of this study will make a noteworthy contribution to cutaneous alterations associated with drug abuse which are regarded as the earliest clinical manifestations, and this SEM approach is a very specific and effective tool in the detection of abuse of respective drugs, leading early treatment. PMID:26309532

  13. 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.

  14. 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.

  15. Electron microscopic investigation of the diffusion of Bacillus licheniformis alpha-amylase into corn starch granules.

    PubMed

    Helbert, W; Schülein, M; Henrissat, B

    1996-10-01

    A method for the direct electron microscopic observation of amylases in interaction with starch granules is presented. The technique involves immuno-gold labeling of the enzymes and cross-sectioning of hydrated starch granules. This approach allows the analysis of the internal degradation of starch with a concomitant visualization of enzymes at the sites of hydrolysis. The visualization of enzymes at the surface, inside the channel and inside the core of the degraded granules shows that the alpha-amylase molecules first proceed from the surface toward the center (centripetal hydrolysis). Then the core is completely degraded from within by erosion of its periphery (centrifugal hydrolysis). In the first case (centripetal hydrolysis), the enzymes act by progressing along the polysaccharide chains. By contrast, the centrifugal hydrolysis leads to even erosion, indicative of a more diffusive motion of the enzymes.

  16. 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.

  17. [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.

  18. Microscopic investigation of electronic inhomogeneity induced by substitutions in quantum critical CeCoIn5

    NASA Astrophysics Data System (ADS)

    Ronning, Filip; Sakai, Hironori; Zhu, Jianxin; Wakeham, Nicholas; Yasuoka, Hiroshi; Tokunaga, Yo; Kambe, Shin; Bauer, Eric; Thompson, Joe

    In Cd-doped CeCoIn5 magnetic order can be suppressed by pressure giving rise to a dome of superconductivity surrounding a quantum critical point (QCP). However, the typical non-Fermi liquid (NFL) signatures expected at this QCP are absent. In contrast, in Sn-doped CeRhIn5, pressure also suppresses magnetism giving rise to a dome of superconductivity, but in this case, the NFL signatures ARE observed at the QCP. We presents results using nuclear quadrupole resonance to probe microscopically the response of the prototypical quantum-critical metal CeCoIn5 to substitutions of small amounts of Sn and Cd for In. These substituents induce very different local electronic environments as observed by site dependent spin lattice relaxation rates 1/T1. Cd-doped samples generate a much more inhomogeneous spin environment than observed in Sn-doped samples. This difference naturally explains the presence and absence of NFL signatures at the respective QCPs mentioned above. The effects found here illustrate the need for care in general when interpreting NFL properties determined by macroscopic measurements achieved by chemical substitutions.

  19. 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.

  20. Electron microscopic investigation of crystal lattice bending-torsion and internal stresses in deformed polycrystalline alloys

    SciTech Connect

    Koneva, N. A. Kozlov, E. V.

    2016-01-15

    Generalization of the results of electron microscopy investigations of the crystal lattice bending-torsion (χ) and the internal stresses (IS) was conducted. The deformed polycrystalline alloys and steels were investigated. The sources of χ and IS origin were established. The regularities of their change with the distance from the sources and the evolution with deformation were revealed. The contribution of IS into the deformation resistance was determined. The nature of formation of two sequences of dislocation substructure transformations during deformation of alloys was established.

  1. Scanning electron microscope investigation on the process of healing of skin wounds in Cirrhinus mrigala.

    PubMed

    Verma, Neeraj; Kumari, Usha; Mittal, Swati; Mittal, Ajay Kumar

    2017-08-11

    Present scanning electron microscope study, reports healing of excised skin wounds in Cirrhinus mrigala. Healing process of wounds, inflicted on head skin, using biopsy punch was observed at intervals-0 hour (h), 1, 2, 4, 6, 12 h, 1 day (d) 2 and 4 d. Accumulation of mucus in wound region within 1h after infliction of wound has been considered an immediate measure to provide protection to injured skin from microbial invasion and other external environmental hazards. On infliction of wound, mobilization of epithelial cells at wound edge is associated with disturbance of coaptive relationship of epithelial cells till original coaptive stability is reached. At 6-12 h appearance of epidermal ridge in region of contact of migrating fronts is due to piling up of epithelial cells. This is associated with cessation of migration of epithelial cells and their simultaneous continual arrival in the region. Speedy epithelialization of skin wounds in C. mrigala like in other fishes, compared to that of mammals and other higher vertebrates, is possibly facilitated owing to surrounding wet external environment. Microridges in initial stages of wound healing appear fragmented without particular orientation. Further, epithelial cells in epithelium in wound region and in region adjacent to wound elongate. These changes are associated with the stretching of epithelial cells indicating their streaming and migration, toward wound. Presence of superficial neuromasts, smallest functional units of lateral line system, a hydrodynamic sensory system, has been associated with important functional significance in fish. © 2017 Wiley Periodicals, Inc.

  2. Neonatal lines in the enamel of primary teeth--a morphological and scanning electron microscopic investigation.

    PubMed

    Sabel, Nina; Johansson, Carina; Kühnisch, Jan; Robertson, Agneta; Steiniger, Frank; Norén, Jörgen G; Klingberg, Gunilla; Nietzsche, Sandor

    2008-10-01

    The neonatal line (NNL) is in principle found in all primary teeth and the line represents the time of birth. Earlier findings of the appearance of the NNL in light microscope and in microradiographs have shown not only changes in the prism direction of the enamel, but that the NNL has a hypomineralized character. The neonatal line was analyzed in un-decalcified sections of primary lower and central incisors, collected from individuals of different ages utilizing polarized light microscopy, microradiography, scanning electron microscopy (SEM) and X-ray analysis (XRMA). In polarized light the NNL appeared to have a more porous structure than the enamel in general. The appearance of the NNL as a dark line in microradiographs is interpreted as the NNL being less mineralized than neighbouring enamel. Analysis with ImageJ visualized the reduction of the amount of grey value, indicating that the NNL is less mineralized. Analysis of the NNL in SEM showed a reduction of the diameter of enamel prisms, the more narrow diameters continued through the postnatal enamel. A change of the growth direction of the prisms was also observed at the NNL. In a three-dimensional image the NNL appeared as a grove, however, in non-etched enamel no grove was seen. The elemental analyses with XRMA showed no marked changes in the content of C, Ca, P, N, O or S in the area around the NNL. The NNL is an optical phenomenon due to alterations in height, and degree of mineralization of the enamel prisms.

  3. Ultra-structural hair alterations in Friedreich's ataxia: A scanning electron microscopic investigation.

    PubMed

    Turkmenoglu, F Pinar; Kasirga, U Baran; Celik, H Hamdi

    2015-08-01

    Friedreich's ataxia (FRDA) is an autosomal recessive inherited disorder involving progressive damage to the central and peripheral nervous systems and cardiomyopathy. FRDA is caused by the silencing of the FXN gene and reduced levels of the encoded protein, frataxin. Frataxin is a mitochondrial protein that functions primarily in iron-sulfur cluster synthesis. Skin disorders including hair abnormalities have previously been reported in patients with mitochondrial disorders. However, to our knowledge, ultra-structural hair alterations in FRDA were not demonstrated. The purpose of this study was to determine ultra-structural alterations in the hairs of FRDA patients as well as carriers. Hair specimen from four patients, who are in different stages of the disease, and two carriers were examined by scanning electron microscope. Thin and weak hair follicles with absence of homogeneities on the cuticular surface, local damages of the cuticular layer, cuticular fractures were detected in both carriers and patients, but these alterations were much more prominent in the hair follicles of patients. In addition, erosions on the surface of the cuticle and local deep cavities just under the cuticular level were observed only in patients. Indistinct cuticular pattern, pores on the cuticular surface, and presence of concavities on the hair follicle were also detected in patients in later stages of the disease. According to our results, progression of the disease increased the alterations on hair structure. We suggest that ultra-structural alterations observed in hair samples might be due to oxidative stress caused by deficient frataxin expression in mitochondria. © 2015 Wiley Periodicals, Inc.

  4. Athena microscopic Imager investigation

    USGS Publications Warehouse

    Herkenhoff, K. E.; Squyres, S. W.; Bell, J.F.; Maki, J.N.; Arneson, H.M.; Bertelsen, P.; Brown, D.I.; Collins, S.A.; Dingizian, A.; Elliott, S.T.; Goetz, W.; Hagerott, E.C.; Hayes, A.G.; Johnson, M.J.; Kirk, R.L.; McLennan, S.; Morris, R.V.; Scherr, L.M.; Schwochert, M.A.; Shiraishi, L.R.; Smith, G.H.; Soderblom, L.A.; Sohl-Dickstein, J. N.; Wadsworth, M.V.

    2003-01-01

    The Athena science payload on the Mars Exploration Rovers (MER) includes the Microscopic Imager (MI). The MI is a fixed-focus camera mounted on the end of an extendable instrument arm, the Instrument Deployment Device (IDD). The MI was designed to acquire images at a spatial resolution of 30 microns/pixel over a broad spectral range (400-700 nm). The MI uses the same electronics design as the other MER cameras but has optics that yield a field of view of 31 ?? 31 mm across a 1024 ?? 1024 pixel CCD image. The MI acquires images using only solar or skylight illumination of the target surface. A contact sensor is used to place the MI slightly closer to the target surface than its best focus distance (about 66 mm), allowing concave surfaces to be imaged in good focus. Coarse focusing (???2 mm precision) is achieved by moving the IDD away from a rock target after the contact sensor has been activated. The MI optics are protected from the Martian environment by a retractable dust cover. The dust cover includes a Kapton window that is tinted orange to restrict the spectral bandpass to 500-700 nm, allowing color information to be obtained by taking images with the dust cover open and closed. MI data will be used to place other MER instrument data in context and to aid in petrologic and geologic interpretations of rocks and soils on Mars. Copyright 2003 by the American Geophysical Union.

  5. A photoemission electron microscope investigation of chemical vapor deposition diamond films and diamond nucleation

    SciTech Connect

    Wang, C.

    1993-12-31

    CVD diamond nucleation is investigated using the hot filament technique. The stability of CVD diamond at elevated temperatures in vacuum, O{sub 2}, and atomic hydrogen environments are studied using photoemission electron microscopy (PEEM) combined with in-vacuo x-ray photoelectron spectroscopy (XPS). Dissolution, oxidation, and atomic hydrogen etching processes of CVD diamond are observed in real-time. Low field cold electron emission from CVD diamond films has been observed for the first time by PEEM. Nucleation density Mo substrates could be increased from 10{sup 4} to 10{sup 8}/cm{sup 2} by polishing. Heating the substrate to 870{degrees}C in vacuum prior to deposition, or above 1000{degrees}C at the beginning of deposition, reduced nucleation by more than 100-fold. Reduction in nucleation sites is attributed to annealing. Nucleation on Mo{sub 2}C substrates was found to be very poor (10{sup 4}/cm{sup 2}), which shows carbide alone does not promote nucleation. Carbide formation may remove nucleation sites. CVD diamond was found to dissolve into the Mo substrate in vacuum at about 1200{degrees}C. XPS showed formation of Mo{sub 2}C when the diamond dissolved. Diamond oxidation to gas phase products occurred directly at about 600{degrees}C, with no observable participation by the substrate. No detectable etching by atomic hydrogen at a pressure 1 {times} 10{sup {minus}4} torr was observed. Boron doped and `pure` CVD diamond films were found to emit electrons at room temperature under the action of the accelerating electric field of the PEEM (about 30 kV/cm) without photon excitation. The mechanism underlying this phenomenon was investigated with PEEM and by studying the emission current-vs-voltage characteristics of the CVD diamond films. Morphology and crystalline orientation were found to play only a minor role. Impurities in the CVD diamond structure lowers the potential barrier substantially; tunneling of electrons into the vacuum is facile.

  6. The temporal and spatial separation of specific syntheses in the process of chondrogenesis (electron microscopic investigation).

    PubMed

    Kerkis, A Y; Kristolyubova, N B

    1975-05-01

    The ultrastructural of the chondroblasts was investigated in vitro by the methods of light and electron microscopy, determining the degree of differentiation of the individual cells. It was found that in the process of differentiation, the surface area of the membranes of the rough endoplasmic reticulum undergoes a five-fold increase, while the concentration of free ribosomes in the cytoplasm decreases. The total concentration of free ribosomes and those attached to the membranes per unit volume is unchanged and is approximately 5500 ribosomes per mu3. The use of H3-proline showed that collagen is synthesized on free polyribosomes in the cytoplasm, and not on the rough endoplasmic reticulum. A hypothesis was advanced on the temporal and spatial separation of specific syntheses in the cartilage, playing an important role in the differentiation of the chondroblasts.

  7. Scanning electron microscope investigation of the structural growth in thick sputtered coatings

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1975-01-01

    Sputtered S-Monel, silver, and 304 stainless steel coatings and molybdenum disulfide coatings were deposited on mica and metal substrates with various surface finishes to investigate the structural growth of the coating by scanning electron microscopy. The geometry and the surface morphology of the nodules are characterized. Compositional changes within the coating were analyzed by energy dispersive X-ray analysis. Defects in the surface finish act as preferential nucleation sites and form isolated overlapping and complex nodules and various unusual surface overgrowths on the coating. The nodule boundaries are very vulnerable to chemical etching and these nodules do not disappear after full annealing. Further, they have undesirable effects on mechanical properties; cracks are initiated at the nodules when the coating is stressed by mechanical forces.

  8. In-situ investigation of laser surface modifications of WC-Co hard metals inside a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Mueller, H.; Wetzig, K.; Schultrich, B.; Pompe, Wolfgang; Chapliev, N. I.; Konov, Vitaly I.; Pimenov, S. M.; Prokhorov, Alexander M.

    1989-05-01

    The investigation of laser interaction with solid surfaces and of the resulting mechanism of surface modification are of technical interest to optimize technological processes, and they are also of fundamental scientific importance. Most instructive indormation is available with the ail of the in-situ techniques. For instance, measuring of the photon emission of the irradiated surface ane the plasma torch (if it is produced) simultaneously to laser action, makes it possible to gain a global characterization of the laser-solid interaction. In order to obtain additional information about surface and structure modifications in microscopic detail , a laser and scanning electron microscope were combined in to a tandem equipment (LASEM). Inside this eqiipment the microscopic observation is carried out directly at the laser irradiated area without any displacement of the sample. In this way, the stepwise development of surface modification during multipulse irradiation is visible in microscopic details and much more reliable information about the surface modification process is obtainable in comparison to an external laser irradiation. Such kind of equipments were realized simultaneously and independently in the Institut of General Physics (Moscow) and the Central Institute of Solid State Physics and Material Research (Dresden) using a CO2 and a LTd-glass-laser, respectively. In the following the advantages and possibilities of a LASEM shall be demonstrated by some selected investigations of WC-CO hardmeta. The results were obtained in collaboration by both groups with the aid of the pulsed CO2-laser. The TEA CO2 laser was transmitted through a ZnSe-window into the sample chamber of the SEM and focused ofAo tfte sample surface. It was operated in TEM - oo mode with a repetition rate of about 1 pulse per second. A peak power density of about 160 MW/cm2 was achieved in front of the sample surface.

  9. Trace element carriers in combined sewer during dry and wet weather: an electron microscope investigation.

    PubMed

    El Samrani, A G; Lartiges, B S; Ghanbaja, J; Yvon, J; Kohler, A

    2004-04-01

    The nature of trace element carriers contained in sewage and combined sewer overflow (CSO) was investigated by TEM-EDX-Electron diffraction and SEM-EDX. During dry weather, chalcophile elements were found to accumulate in sewer sediments as early diagenetic sulfide phases. The sulfurization of some metal alloys was also evidenced. Other heavy metal carriers detected in sewage include metal alloys, some iron oxihydroxide phases and neoformed phosphate minerals such as anapaite. During rain events, the detailed characterization of individual mineral species allowed to differentiate the contributions from various specific sources. Metal plating particles, barite from automobile brake, or rare earth oxides from catalytic exhaust pipes, originate from road runoff, whereas PbSn alloys and lead carbonates are attributed to zinc-works from roofs and paint from building siding. Soil contribution can be traced by the presence of clay minerals, iron oxihydroxides, zircons and rare earth phosphates. However, the most abundant heavy metal carriers in CSO samples were the sulfide particles eroded from sewer sediments. The evolution of relative abundances of trace element carriers during a single storm event, suggests that the pollution due to the "first flush" effect principally results from the sewer stock of sulfides and previously deposited metal alloys, rather than from urban surface runoff.

  10. Investigation of C3 S hydration mechanism by transmission electron microscope (TEM) with integrated Super-X(TM) EDS system.

    PubMed

    Sakalli, Y; Trettin, R

    2017-07-01

    Tricalciumsilicate (C3 S, Alite) is the major component of the Portland cement clinker. Hydration of Alite is decisive in influencing the properties of the resulting material. This is due to its high content in cement. The mechanism of the hydration of C3 S is very complicated and not yet fully understood. There are different models describing the hydration of C3 S in various ways. In this work for a better understanding of hydration mechanism, the hydrated C3 S was investigated by using the transmission electron microscope (TEM) and for the first time, the samples for the investigations were prepared by using of focused ion beam from sintered pellets of C3 S. Also, an FEI Talos F200x with an integrated Super-X EDS system was used for the investigations. FEI Talos F200X combines outstanding high-resolution S/TEM and TEM imaging with energy dispersive X-ray spectroscopy signal detection, and 3D chemical characterization with compositional mapping. TEM is a very powerful tool for material science. A high energy beam of electrons passes through a very thin sample, and the interactions between the electrons and the atoms can be used to observe the structure of the material and other features in the structure. TEM can be used to study the growth of layers and their composition. TEM produces high-resolution, two-dimensional images and will be used for a wide range of educational, science and industry applications. Chemical analysis can also be performed. The purpose of these investigations was to get the information about the composition of the C-S-H phases and some details of the nanostructure of the C-S-H phases. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  11. ELECTRON MICROSCOPIC AND MICRODIFFRACTION INVESTIGATION OF NONMETALLIC IMPURITIES IN MOLYBDENUM AND ITS ALLOYS,

    DTIC Science & Technology

    and distribution of the inclusions were determined in specimens of molybdenum produced by electron - beam melting and in molybdenum alloys containing...specimens. The electron - beam melting and annealing were done in a vacuum of 10-4-10-5 Hg mm. (Author)

  12. The lamina propria of vertebrate seminiferous tubules: a comparative light and electron microscopic investigation.

    PubMed

    Christl, H W

    1990-01-01

    The lamina propria of the seminiferous tubules was compared by means of light and electron microscopy in specimens obtained from the following vertebrates: Mute swan, northern mallard, blackbird, grey short-tailed opossum, north american opossum, european rabbit, mouse, rat, golden hamster, mini pig, bull, llama, roebuck, horse, coati, cat, dog, java monkey, orang utan. The lamina propria consists of basal lamina, ground substance, collagen fibers, fibroblasts and myofibroblasts. Myofibroblasts are characterized by myofilaments, dense patches and a basal lamina covering their plasmalemma. The layers of myofibroblasts always lie adjacent to the germinal epithelium, while the surrounding fibroblast layers are located peripherally.

  13. Transmission electron microscope and rock magnetic investigations of remanence carriers in a Precambrian metadolerite

    NASA Astrophysics Data System (ADS)

    Morgan, G. E.; Smith, P. P. K.

    1981-04-01

    A Precambrian metadolerite dyke has two distinct types of remanence carriers; those with medium/high coercivities (unblocking fields of 20-120 mT) and those with low coercivities (unblocking fields of <15 mT). Optical examination reveals numerous submicron probably opaque inclusions in the plagioclase feldspar and also large opaque grains consisting of coarse oxidation-exsolution intergrowths of magnetite and ilmenite. All opaque phases have been examined using transmission electron microscopy together with microanalysis and electron diffraction. The submicron inclusions in the plagioclase are titanomagnetites (0 < x ≤ 0.14) with a size range between about 0.01 and 0.5 μm and axial ratios between 1 (equidimensional) and about 0.3. Many of these inclusions fall in the single-domain field but some are probably pseudo-single-domain. The large opaque grains contain almost pure magnetite and ilmenite and show no fine-scale exsolution; the magnetite regions of the intergrowths are of multidomain size and reveal multidomain structure under Lorentz electron microscopy. There are also some primary ilmenites containing very fine exsolved haematite, and there are very fine plates of ilmenite and very elongate needles of magnetite within the augite. Experiments on artificial samples containing very carefully prepared separates of plagioclase and large opaque grains show that the pure plagioclase acquires a remanence with unblocking fields of 20-140 mT and blocking temperatures of 390-590°C and the large opaque grains acquire a remanence with unblocking fields of less than 15 mT but a wide range of blocking temperatures up to about 570°C. It is concluded that the medium/high coercivity component of remanence in the rock is carried largely or possibly entirely by the submicron magnetites within the plagioclase and that the low coercivity component is carried largely or entirely by the multidomain magnetites in the large opaques. The contribution of the magnetite needles in

  14. [Experimental investigations on cell resorption from the peritoneal cavity by use of the scanning electron microscope (author's transl)].

    PubMed

    Remmele, W; Richter, I E; Wildenhof, H

    1975-10-01

    1. It is well known that microscopically small particles may be absorbed from the peritoneal cavity via the large lymphatic vessels. The present experiments were carried out in order to elucidate the site of the absorption. In addition, the role of transperitoneal transport of neoplastic cells as a possible cause of cancer metastases was studied. 2. The peritoneal surface of 40 rats and mice was studied with the scanning electron microscope (diaphragm, lateral abdominal wall). The investigations were carried out in 8 rats and 3 mice 24 hrs following the intraperitoneal injection of washed homologous erythrocytes and in 20 rats and 5 mice 24 hrs after the intraperitoneal injection of Ehrlich ascites tumor cells. 2 rats and 2 mice served as controls. 3. In the control animals no stomata could be shown in the peritoneum of the diaphragm or in the lateral abdominal wall. 4. The i.p. injection of erythrocytes was followed by the appearance of stomata in the peritoneal surface of the diaphragm, and absorption of erythrocytes could be demonstrated. No stomata were found in the peritoneum of the lateral abdominal wall. 5. Tumor cells were found in the stomata following the i.p. injection of ascites tumor cells. It is concluded that a lympho-hematogenous spread of tumor cells seems probable at least in the early stage of tumor infiltration of the peritoneum. This stage is followed by implantation of the tumor cells on the peritoneum.

  15. Electron microscope studies

    SciTech Connect

    Crewe, A.V.; Kapp, O.H.

    1991-06-01

    This year our laboratory has continued to make progress in the design of electron-optical systems, in the study of structure-function relationships of large multi-subunit proteins, in the development of new image processing software and in achieving a workable sub-angstrom STEM. We present an algebraic approach to the symmetrical Einzel (unipotential) lens wherein we simplify the analysis by specifying a field shape that meets some preferred set of boundary or other conditions and then calculate the fields. In a second study we generalize this approach to study of three element electrostatic lenses of which the symmetrical Einzel lens is a particular form. The purpose is to develop a method for assisting in the design of a lens for a particular purpose. In our biological work we study a stable and functional dodecameric complex of globin chains from the hemoglobin of Lumbricus terrestris. This is a complex lacking the linker'' subunit first imaged in this lab and required for maintenance of the native structure. In addition, we do a complete work-up on the hemoglobin of the marine polychaete Eudistylia vancouverii demonstrating the presence of a hierarchy of globin complexes. We demonstrate stable field-emission in the sub-angstrom STEM and the preliminary alignment of the beam. We continue our exploration of a algorithms for alignment of sequences of protein and DNA. Our computer facilities now include four second generation RISC workstations and we continue to take increasing advantage of the floating-point and graphical performance of these devices.

  16. 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.

  17. 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.

  18. Twelve-point scale grading system of scanning electron microscopic examination to investigate subtle changes in damaged hair surface.

    PubMed

    Lee, S Y; Choi, A R; Baek, J H; Kim, H O; Shin, M K; Koh, J S

    2016-11-01

    To assess the hair surface condition, scanning electron microscope (SEM) is commonly used and it remains an indispensable hair morphology characterization technique. Yet, the technique is criticized for having subjective viewpoints and limitations in distinguishing the appearance of cuticle layers. The aim of this study is to establish an objective classification system and also to subdivide by detailed description of damaged cuticle layers. Hair samples were collected from female subjects (n = 500) who participated in hair efficacy study and Asian hair bunches (n = 180) that were previously collected. Damage to hair was initiated by chemical, heat stress and ultraviolet irradiation. We suggested the grading criterion on a 12-point scale and compared with a wide range grading system on a 5-point scale. We evaluated other hair surface-related parameters such as hair luster-ring and combing load to verify the validity and efficacy of our new grading system. The grading criterion on our 12-point scale revealed an improved discrimination compared to the wide range grading system. Hair surface-related parameters were significantly improved after hair care product, and these tendencies were likely to be determined to be similarly improved using the 12-point scale grading system. The 12-point scale classification system was demonstrated to be a more precise standardization and appropriate evaluation method to investigate the subtle distinction of the hair shaft after hair care product application. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. 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

  20. Evaluation of Electrospray as a Sample Preparation Tool for Electron Microscopic Investigations: Toward Quantitative Evaluation of Nanoparticles.

    PubMed

    Mielke, Johannes; Dohányosová, Pavla; Müller, Philipp; López-Vidal, Silvia; Hodoroaba, Vasile-Dan

    2017-02-01

    The potential of electrospray deposition, for the controlled preparation of particles for imaging in electron microscopes, is evaluated on various materials: from mono-modal suspensions of spherical particles to multimodal suspensions and to real-world industrial materials. It is shown that agglomeration is reduced substantially on the sample carrier, compared with conventional sample preparation techniques. For the first time, it is possible to assess the number concentration of a tri-modal polystyrene suspension by electron microscopy, due to the high deposition efficiency of the electrospray. We discovered that some suspension stabilizing surfactants form artifact particles during electrospraying. These can be avoided by optimizing the sprayed suspension.

  1. Spectral Interferometry with Electron Microscopes.

    PubMed

    Talebi, Nahid

    2016-09-21

    Interference patterns are not only a defining characteristic of waves, but also have several applications; characterization of coherent processes and holography. Spatial holography with electron waves, has paved the way towards space-resolved characterization of magnetic domains and electrostatic potentials with angstrom spatial resolution. Another impetus in electron microscopy has been introduced by ultrafast electron microscopy which uses pulses of sub-picosecond durations for probing a laser induced excitation of the sample. However, attosecond temporal resolution has not yet been reported, merely due to the statistical distribution of arrival times of electrons at the sample, with respect to the laser time reference. This is however, the very time resolution which will be needed for performing time-frequency analysis. These difficulties are addressed here by proposing a new methodology to improve the synchronization between electron and optical excitations through introducing an efficient electron-driven photon source. We use focused transition radiation of the electron as a pump for the sample. Due to the nature of transition radiation, the process is coherent. This technique allows us to perform spectral interferometry with electron microscopes, with applications in retrieving the phase of electron-induced polarizations and reconstructing dynamics of the induced vector potential.

  2. Spectral Interferometry with Electron Microscopes

    PubMed Central

    Talebi, Nahid

    2016-01-01

    Interference patterns are not only a defining characteristic of waves, but also have several applications; characterization of coherent processes and holography. Spatial holography with electron waves, has paved the way towards space-resolved characterization of magnetic domains and electrostatic potentials with angstrom spatial resolution. Another impetus in electron microscopy has been introduced by ultrafast electron microscopy which uses pulses of sub-picosecond durations for probing a laser induced excitation of the sample. However, attosecond temporal resolution has not yet been reported, merely due to the statistical distribution of arrival times of electrons at the sample, with respect to the laser time reference. This is however, the very time resolution which will be needed for performing time-frequency analysis. These difficulties are addressed here by proposing a new methodology to improve the synchronization between electron and optical excitations through introducing an efficient electron-driven photon source. We use focused transition radiation of the electron as a pump for the sample. Due to the nature of transition radiation, the process is coherent. This technique allows us to perform spectral interferometry with electron microscopes, with applications in retrieving the phase of electron-induced polarizations and reconstructing dynamics of the induced vector potential. PMID:27649932

  3. Microscopic investigation of electronic inhomogeneity induced by substitutions in a quantum critical metal CeCoIn5

    NASA Astrophysics Data System (ADS)

    Sakai, H.; Ronning, F.; Zhu, J.-X.; Wakeham, N.; Yasuoka, H.; Tokunaga, Y.; Kambe, S.; Bauer, E. D.; Thompson, J. D.

    2015-09-01

    Chemical substitutions are used commonly to tune a magnetic transition to zero temperature, but the resulting non-Fermi-liquid (NFL) behavior is nonuniversal. We have used nuclear quadrupole resonance to probe microscopically the response of a prototypical quantum critical metal CeCoIn5 to substitutions of small amounts of Sn and Cd for In. These substituents induce very different local electronic environments as observed by site-dependent spin lattice relaxation rates 1 /T1 that influence the NFL behavior. The effects found here illustrate the need for care in interpreting NFL properties determined by macroscopic measurements.

  4. Persistent extraradicular infection in root-filled asymptomatic human tooth: scanning electron microscopic analysis and microbial investigation after apical microsurgery.

    PubMed

    Signoretti, Fernanda G C; Endo, Marcos S; Gomes, Brenda P F A; Montagner, Francisco; Tosello, Fernanda B; Jacinto, Rogério C

    2011-12-01

    Procedural accidents have a negative effect on healing and might contribute to the persistence of infections in inaccessible apical areas, requiring surgical intervention. This report describes a case of persistent apical periodontitis of a lower left first molar associated with the sinus tract and a periapical lesion that required nonsurgical endodontic retreatment and apical surgery for resolution. The tooth had received endodontic treatment 3 years ago and had to be retreated using the crown-down technique with chemical auxiliary substance (2% chlorhexidine gel), foramen patency, and enlargement and was filled in a single appointment. The occlusal access cavity was immediately restored with composite resin. After 1 month, it could be observed that the sinus tract persisted and, radiographically, the lesion remained unaltered. Therefore, endodontic microsurgery was indicated. Apical microsurgery was performed under magnification with the use of a dental operating microscope including apicectomy, root end with ultrasound, and sealing with mineral trioxide aggregate. A microbiological sample was collected from the apical lesion. The resected distal root apex was observed by scanning electron microscopy. The following species were detected: Actinomyces naeslundii and Actinomyces meyeri, Propionibacterium propionicum, Clostridium botullinum, Parvimonas micra, and Bacteroides ureolyticus; scanning electron microscopic analysis revealed bacterial biofilm surrounding the apical foramen and external radicular surface. Gutta-percha overfilling at the apex because of a zip caused during initial endodontic treatment could be observed. A 6-month follow-up showed apparent radiographic periapical healing, which progressed after 24 months. Gram-positive anaerobic bacteria and extraradicular biofilm seem to participate in the maintenance of persistent periapical pathology, and endodontic retreatment followed by periapical microsurgery proved to be a successful alternative in the

  5. A transmission electron microscope investigation of the effect of lead acetate on the hepatopancreatic ceca of Gammarus pulex.

    PubMed

    Kutlu, Mehtap; Düzen, Ayla; Bayçu, Cengiz; Ozata, Ahmet

    2002-10-01

    The freshwater Amphipod Gammarus pulex is a sensitive indicator organism for environmental contamination. In this study, effects of heavy metal lead acetate were investigated by using electron microscopy techniques. Control group was not expose to lead acetate but experimental group was for 96 h. The ultrastructural changes of hepatopancreatic ceca cells were studied in these two groups by electron microscopy techniques analysing cellular structure, structure of organelles and vacuolization. The number of cells based on the toxic effects of lead acetate was increased compared with the control group. The number and length of cell microvilli was decreased. Additionally degenerated mitocondria, dilation of golgi vesicules and cytoplasmic vacuolization were observed. The results of present study suggest that the exposure to the lead acetate may cause some ultrastructural changes on hepatopancreatic ceca of digestive system in Gammarus pulex. The significance of this change in terms of environmental toxicology needs to be further studied.

  6. The Athena Microscopic Imager Investigation

    NASA Technical Reports Server (NTRS)

    Herkenhoff, K. E.; Aquyres, S. W.; Bell, J. F., III; Maki, J. N.; Arneson, H. M.; Brown, D. I.; Collins, S. A.; Dingizian, A.; Elliot, S. T.; Geotz, W.

    2003-01-01

    The Athena science payload on the Mars Exploration Rovers (MER) includes the Microscopic Imager (MI) [1]. The MI is a fixed-focus camera mounted on the end of an extendable instrument arm, the Instrument Deployment Device (IDD; see Figure 1).The MI was designed to acquire images at a spatial resolution of 30 microns/pixel over a broad spectral range (400 - 700 nm; see Table 1). Technically, the microscopic imager is not a microscope: it has a fixed magnification of 0.4 and is intended to produce images that simulate a geologist s view through a common hand lens. In photographers parlance, the system makes use of a macro lens. The MI uses the same electronics design as the other MER cameras [2, 3] but has optics that yield a field of view of 31 31 mm across a 1024 1024 pixel CCD image (Figure 2). The MI acquires images using only solar or skylightillumination of the target surface. A contact sensor is used to place the MI slightly closer to the target surface than its best focus distance (about 66 mm), allowing concave surfaces to be imaged in good focus. Because the MI has a relatively small depth of field (3 mm), a single MI image of a rough surface will contain both focused and unfocused areas. Coarse focusing will be achieved by moving the IDD away from a rock target after the contact sensor is activated. Multiple images taken at various distances will be acquired to ensure good focus on all parts of rough surfaces. By combining a set of images acquired in this way, a completely focused image can be assembled. Stereoscopic observations can be obtained by moving the MI laterally relative to its boresight. Estimates of the position and orientation of the MI for each acquired image will be stored in the rover computer and returned to Earth with the image data. The MI optics will be protected from the Martian environment by a retractable dust cover. The dust cover includes a Kapton window that is tinted orange to restrict the spectral bandpass to 500-700 nm

  7. Argon broad ion beam tomography in a cryogenic scanning electron microscope: a novel tool for the investigation of representative microstructures in sedimentary rocks containing pore fluid.

    PubMed

    Desbois, G; Urai, J L; Pérez-Willard, F; Radi, Z; Offern, S; Burkart, I; Kukla, P A; Wollenberg, U

    2013-03-01

    The contribution describes the implementation of a broad ion beam (BIB) polisher into a scanning electron microscope (SEM) functioning at cryogenic temperature (cryo). The whole system (BIB-cryo-SEM) provides a first generation of a novel multibeam electron microscope that combines broad ion beam with cryogenic facilities in a conventional SEM to produce large, high-quality cross-sections (up to 2 mm(2)) at cryogenic temperature to be imaged at the state-of-the-art SEM resolution. Cryogenic method allows detecting fluids in their natural environment and preserves samples against desiccation and dehydration, which may damage natural microstructures. The investigation of microstructures in the third dimension is enabled by serial cross-sectioning, providing broad ion beam tomography with slices down to 350 nm thick. The functionalities of the BIB-cryo-SEM are demonstrated by the investigation of rock salts (synthetic coarse-grained sodium chloride synthesized from halite-brine mush cold pressed at 150 MPa and 4.5 GPa, and natural rock salt mylonite from a salt glacier at Qom Kuh, central Iran). In addition, results from BIB-cryo-SEM on a gas shale and Boom Clay are also presented to show that the instrument is suitable for a large range of sedimentary rocks. For the first time, pore and grain fabrics of preserved host and reservoir rocks can be investigated at nm-scale range over a representative elementary area. In comparison with the complementary and overlapping performances of the BIB-SEM method with focused ion beam-SEM and X-ray tomography methods, the BIB cross-sectioning enables detailed insights about morphologies of pores at greater resolution than X-ray tomography and allows the production of large representative surfaces suitable for FIB-SEM investigations of a specific representative site within the BIB cross-section. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

  8. Scanning electron microscopic investigations of root structural modifications arising from growth in crude oil-contaminated sand.

    PubMed

    Balasubramaniyam, Anuluxshy; Harvey, Patricia J

    2014-11-01

    The choice of plant for phytoremediation success requires knowledge of how plants respond to contaminant exposure, especially their roots which are instrumental in supporting rhizosphere activity. In this study, we investigated the responses of plants with different architectures represented by beetroot (Beta vulgaris), a eudicot with a central taproot and many narrower lateral roots, and tall fescue (Festuca arundinacea), a monocot possessing a mass of threadlike fibrous roots to grow in crude oil-treated sand. In this paper, scanning electron microscopy was used to investigate modifications to plant root structure caused by growth in crude oil-contaminated sand. Root structural disorders were evident and included enhanced thickening in the endodermis, increased width of the root cortical zone and smaller diameter of xylem vessels. Inhibition in the rate of root elongation correlated with the increase in cell wall thickening and was dramatically pronounced in beetroot compared to the roots of treated fescue. The latter possessed significantly fewer (p < 0.001) and significantly shorter (p < 0.001) root hairs compared to control plants. Possibly, root hairs that absorb the hydrophobic contaminants may prevent contaminant absorption into the main root and concomitant axile root thickening by being sloughed off from roots. Tall fescue exhibited greater root morphological adaptability to growth in crude oil-treated sand than beetroot and, thus, a potential for long-term phytoremediation.

  9. Electron microscopic investigation of the kinetics of the layer and island crystallization of amorphous V2O3 films deposited by pulsed laser evaporation

    NASA Astrophysics Data System (ADS)

    Bagmut, A. G.

    2017-06-01

    An electron microscopic investigation was performed on the kinetics of the layer and island crystallization of amorphous V2O3 films deposited by pulsed laser evaporation of vanadium in an oxygen atmosphere. The crystallization was initiated by the action of an electron beam on an amorphous film in the column of a transmission electron microscope. The kinetic curves were plotted on the basis of a frame-by-frame analysis of the video recorded during the crystallization of the film. It was found that the layer crystallization of amorphous films is characterized by a quadratic dependence of the fraction of the crystalline phase x on the time t, whereas the island crystallization is described by an exponential dependence of x on t. The kinetic curves of island crystallization of amorphous films were analyzed on the basis of the α-version of the Kolmogorov model. For each type of crystallization, there are specific values of the dimensionless relative length unit δ0, which is equal to the ratio of the characteristic length unit to the parameter characterizing the unit cell of the crystal. It was established that, for the layer crystallization, the relative length unit lies in the range δ0 4300-4700, whereas for the fine-grained island crystallization, it amounts to δ0 110.

  10. 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)

  11. 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)

  12. Ultrafast Electron Microscopes: Design Criteria, Electron Sources, and Column Modeling

    NASA Astrophysics Data System (ADS)

    Berger, Joel A.

    Dynamic Transmission Electron Microscopy, and its picosecond/femtosecond subclass Ultrafast Electron Microscopy, is an emerging field in instrumentation science. It attempts to combine the nanoscale spatial resolution of transmission electron microscopes with the temporal resolution of modern ultrafast lasers. In this thesis, I present my contributions to this young field. These include a novel model for simulating the dynamics of ultrafast electron pulses in electron microscope systems, design criteria for constructing such a system, and theoretical and experimental groundwork geared towards selecting a useful photocathode for electron pulse generation. I also present the prototype ultrafast electron microscope system being built at UIC.

  13. Seismic isolation of an electron microscope

    SciTech Connect

    Godden, W.G.; Aslam, M.; Scalise, D.T.

    1980-01-01

    A unique two-stage dynamic-isolation problem is presented by the conflicting design requirements for the foundations of an electron microscope in a seismic region. Under normal operational conditions the microscope must be isolated from ambient ground noise; this creates a system extremely vulnerable to seismic ground motions. Under earthquake loading the internal equipment forces must be limited to prevent damage or collapse. An analysis of the proposed design solution is presented. This study was motivated by the 1.5 MeV High Voltage Electron Microscope (HVEM) to be installed at the Lawrence Berkeley Laboratory (LBL) located near the Hayward Fault in California.

  14. Cathodoluminescence in the scanning transmission electron microscope.

    PubMed

    Kociak, M; Zagonel, L F

    2016-12-19

    Cathodoluminescence (CL) is a powerful tool for the investigation of optical properties of materials. In recent years, its combination with scanning transmission electron microscopy (STEM) has demonstrated great success in unveiling new physics in the field of plasmonics and quantum emitters. Most of these results were not imaginable even twenty years ago, due to conceptual and technical limitations. The purpose of this review is to present the recent advances that broke these limitations, and the new possibilities offered by the modern STEM-CL technique. We first introduce the different STEM-CL operating modes and the technical specificities in STEM-CL instrumentation. Two main classes of optical excitations, namely the coherent one (typically plasmons) and the incoherent one (typically light emission from quantum emitters) are investigated with STEM-CL. For these two main classes, we describe both the physics of light production under electron beam irradiation and the physical basis for interpreting STEM-CL experiments. We then compare STEM-CL with its better known sister techniques: scanning electron microscope CL, photoluminescence, and electron energy-loss spectroscopy. We finish by comprehensively reviewing recent STEM-CL applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Cathodoluminescence in the scanning transmission electron microscope.

    PubMed

    Kociak, M; Zagonel, L F

    2017-05-01

    Cathodoluminescence (CL) is a powerful tool for the investigation of optical properties of materials. In recent years, its combination with scanning transmission electron microscopy (STEM) has demonstrated great success in unveiling new physics in the field of plasmonics and quantum emitters. Most of these results were not imaginable even twenty years ago, due to conceptual and technical limitations. The purpose of this review is to present the recent advances that broke these limitations, and the new possibilities offered by the modern STEM-CL technique. We first introduce the different STEM-CL operating modes and the technical specificities in STEM-CL instrumentation. Two main classes of optical excitations, namely the coherent one (typically plasmons) and the incoherent one (typically light emission from quantum emitters) are investigated with STEM-CL. For these two main classes, we describe both the physics of light production under electron beam irradiation and the physical basis for interpreting STEM-CL experiments. We then compare STEM-CL with its better known sister techniques: scanning electron microscope CL, photoluminescence, and electron energy-loss spectroscopy. We finish by comprehensively reviewing recent STEM-CL applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Light and scanning electron microscope investigations comparing calculus removal using an Er:YAG laser and a frequency-doubled alexandrite laser

    NASA Astrophysics Data System (ADS)

    Rechmann, Peter; Hennig, Thomas; Sadegh, Hamid M. M.; Goldin, Dan S.

    1997-05-01

    With respect to lasers emitting within the mid-IR spectral domain fiber applicators are being developed. Intended is the use of these lasers in periodontal therapy and their application inside the gingival pocket. Aim of the study presented here is to compare the effect of an Er:YAG laser on dental calculus with the results following irradiation with a frequency doubled Alexandrite laser. The surface of freshly extracted wisdom teeth and of extracted teeth suffering from severe periodontitis were irradiated with both laser wavelengths using a standardized application protocol. Calculus on the enamel surface, at the enamel cementum junction and on the root surface was irradiated. For light microscope investigations undecalcified histological sections were prepared after treatment. For the scanning electron microscope teeth were dried in alcohol and sputtered with gold. Investigations revealed that with both laser systems calculus can be removed. Using the frequency doubled Alexandrite laser selective removal of calculus is possible while engaging the Er:YAG laser even at lowest energies necessary for calculus removal healthy cementum is ablated without control.

  17. 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.

  18. Vibrational spectroscopy in the electron microscope

    NASA Astrophysics Data System (ADS)

    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.

    2014-10-01

    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.

  19. Microcalorimetric and electron microscopic investigation on the effects of essential oil from Cymbopogon densiflorus on Staphylococcus aureus.

    PubMed

    Takaisi-Kikuni, N B; Krüger, D; Gnann, W; Wecke, J

    1996-01-01

    Microcalorimetry, optical density measurements and electron microscopy, were used to assess the influence of various amounts of the essential oil of Cymbopogon densiflorus (lemongrass oil) on the metabolic activity, growth and morphology of Staphylococcus aureus. Relatively high concentrations of the oil impaired staphylococcal growth in a bacteriostatic manner (chloramphenicol type), and in low doses metabolism became ineffective due to energy losses in the form of heat. Ultrastructural data revealed morphological changes characteristic for the influence of bactericidal antibiotics inducing bacteriolysis (penicillin type). The essential oil may have antibacterial activity by influencing bacterial targets involved in cytoplasmic and cell wall metabolism.

  20. Electron microscopical investigation on aldrin-induced hepatocyte pathology in Rana catesbeiana, with special emphasis on peroxisomes.

    PubMed

    de Brito-Gitirana, L; Miguel, N C

    2000-08-01

    We examined the effect of aldrin on hepatocyte ultrastructure in liver of Rana catesbeiana. The frogs were experimentally exposed to chemical substance and liver fragments processed for routine transmission electron microscopy. Hepatic peroxisomes were visualized after incubation with alkaline 3,3'-diaminobezidine (DAB) method. Ultrastructural analysis revealed progressive hepatocyte changes induced by this drug. After 2-weeks, in the hepatocytes the nuclear envelop and the cisternae of both smooth and rough endoplasmic reticulum (SER und RER, respectively) were unusually enlarged. Reduction of glycogen granules associated with an increased frequency of lysosomes was observed. Normal appearing peroxisomes were present in clusters. Lipid droplets were also visualuzed. After 4-weeks, there was a new increase of glcogen associated with a great number of mitochondria and peroxisomes. Moreover, SER und RER were still dilated. Intracellular lipid inclusions became more abundant. These results suggest that the aldrin 250 induces ultrastructural changes in the hepatocyte of Rana catesbeiana.

  1. [Dormancy of Candida albicans ATCC10231 in the presence of amphotericin B. Investigation using the scanning electron microscope (SEM)].

    PubMed

    Benmansour, W; Boucherit-Otmani, Z; Boucherit, K

    2014-09-01

    The aim of this study was to visualize the morphology of Candida albicans ATCC10231 in the absence and in the presence of amphotericin B at 0.4 μg/mL, to better understand the phenomenon responsible for a large portion of cases of treatment failure called "dormancy phenomenon". The main objective was to determine the morphological changes adopted by C. albicans in the lag phase extended before resuming normal growth. In order to define the morphological characteristics and surface properties of the cells in the absence and in the presence of amphotericin B at 0.4 μg/mL, cells were cultured in Sabouraud medium at 30°C, and the morphology index was determined by reference to the classification of forms in C. albicans determined by Merson-Davies and Odds. Then, the technique of scanning electron microscopy (SEM) coupled with image analysis was used to measure the surface and determined the morphological properties using the plugin analysis three-dimensional (3D) integrated into the ImageJ software. The dormant phase in C. albicans ATCC10231 grown in Sabouraud liquid at 30°C in the presence of amphotericin B at 0.4 μg/mL extends to 21 hours. The index morphology obtained for the two samples (in the absence and presence of amphotericin B) indicates that the cell even in the presence of amphotericin B retains its yeast form (Mi<1.5) The analysis of microphotography obtained by scanning electron microscopy (SEM) has shown that the cell in the presence of amphotericin B is partially deformed; the deformation is estimated at 33.25%, with various changes in the cell surface. This study showed that the morphology of C. albicans ATCC10231 in the presence of amphotericin B at 0.4 μg/mL changes with partial deformation of the cell. This rate is insufficient to induce cell death, which partly explains the phenomenon of dormancy adopted by C. albicans prior to cell repair and resume normal growth. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  2. Hot isostatic pressing-processed hydroxyapatite-coated titanium implants: light microscopic and scanning electron microscopy investigations.

    PubMed

    Wie, H; Herø, H; Solheim, T

    1998-01-01

    Hot isostatic pressing (HIP) was used in a new procedure to produce hydroxyapatite (HA) coatings on a commercially pure titanium (cpTi) substrate for osseous implantation. Eighteen HIP-processed HA-coated implants were placed in the inferior border of the mandibles in 2 Labrador retriever dogs and left submerged for 3 months. As control specimens, 12 sandblasted cpTi implants were placed in the same mandibles and, to compare the bone reaction, 2 additional plasma-sprayed HA-coated implants (Integral) were placed. Tissue reactions at the bony interfaces of the implants were studied in ground sections with the implants in situ, using ordinary, fluorescent, and polarized light microscopy and scanning electron microscopy (SEM). The HIP-processed HA coatings displayed an increased density in light microscopy and SEM as compared to plasma-sprayed coatings. Direct bone-implant contact was found in all 3 types of surfaces. However, the production of new bone was far more abundant for the HA-coated implants than for sandblasted cpTi implants. The presence of bone-forming and bone-resorbing cells indicated active bone remodeling in the interface area at 3 months after implant placement. The present results support the view that epitaxial bone growth may occur from the HA-coated implant surface. It was concluded that the increased density of the present HIP-processed HA material does not reduce the bioactive properties of the coatings.

  3. Characterization and scanning electron microscopic investigation of crosslinked freeze dried gelatin matrices for study of drug diffusivity and release kinetics.

    PubMed

    Thakur, Goutam; Mitra, Analava; Basak, Amit; Sheet, Debdoot

    2012-02-01

    Drug delivery is a promising technique to enhance the therapeutic efficacy of the drug. However, properties of carrier materials require intense improvement for effective transport of drug molecules. In the current study, attempts have been made to develop freeze dried gelatin matrices cross linked with genipin at various temperatures (5°C, 15°C and 25°C) prior to freeze-drying (-80°C). The freeze dried matrices thus obtained at the said temperatures are characterized for crosslinking density, compression strength, swelling behaviors. The matrix crosslinked at 25°C showed highest Flory-Rehner crosslinking density (467 ± 46) (p<0.05), highest compressive strength (12.36 ± 0.12) (p<0.05) and lowest equilibrium water content. In this context, scanning electron microscopy (SEM) was performed to study the surface morphology (size and shape of pores) of the crosslinked matrices. These images were further processed for quantitative analysis of morphological features, viz., areas, radius, ferret diameter, length of major and minor axis and eccentricity using MATLAB toolboxes. These quantitative analyses correlate transport and the release kinetics of model anti-inflammatory drug (indomethacin) from crosslinked matrices in vitro to tune as a controllable delivery system. The diffusional exponent (n) for all constructs ranging from 0.61 to 0.69 (p<0.05) (0.45

  4. 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.

  5. Nano Robotic Manipulation inside Electron Microscopes

    NASA Astrophysics Data System (ADS)

    Fukuda, Toshio; Nakajima, Masahiro; Liu, Pou

    We report nanomanipulation and nanoassembly through nanorobotic manipulation inside electron microscopes. A hybrid nanorobotic manipulation system, which is integrated with a nanorobotic manipulator inside a transmission electron microscope (TEM) and nanorobotic manipulators inside a scanning electron microscope (SEM), is used. The elasticity of a multi-walled CNT (MWNT) is measured inside a TEM. The telescoping MWNT is fabricated by peeling off outer layers through destructive fabrication process. The electrostatic actuation of telescoping MWNT is directly observed by a TEM. A cutting technique for CNTs assisted by the presence of oxygen gas is also presented. The cutting procedure was conducted in less than 1 minute using a low-energy electron beam inside a scanning electron microscope. A bending technique of a CNT assisted by the presence of oxygen gas is also applied for the 3-D fabrication of nanosturucture. We expect that these techniques will be applied for the rapid prototyping nanoassembly of various CNT nanodevices. For the nano-biological applications, environmental-SEM (E-SEM) nanomanipulation system is also presented with the direct observation of the hydroscopic samples with non-drying treatment.

  6. Automated monitoring to reduce electron microscope downtime.

    PubMed

    Brunner, Matthias J; Resch, Guenter P

    2009-10-01

    High-end transmission electron microscopes are complex and sensitive instruments. Failure of one of the external supplies, malfunction of the microscope hardware or maloperation are typical reasons for subsystems to fail. Especially if undiscovered for a longer period of time, this can cause unnecessary downtime, compromising user access and increasing operating costs. Utilizing the software introduced in this article ("MoniTEM"), we have succeeded to reduce downtime of an FEI Tecnai Polara by coupling constant monitoring of critical subsystems with automatic, remote feedback to the system supervisor, ensuring immediate problem solving. The software described here is freely available from http://www.imba.oeaw.ac.at/monitem/ and can be readily adapted for use with other FEI transmission electron microscopes.

  7. 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

  8. Development of Scanning Ultrafast Electron Microscope Capability.

    SciTech Connect

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

    2016-11-01

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

  9. Optics of high-performance electron microscopes.

    PubMed

    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.

  10. 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.

  11. Isotope analysis in the transmission electron microscope

    PubMed Central

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

    2016-01-01

    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 12C or 13C 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. PMID:27721420

  12. A transmission electron microscope for lecture demonstrations

    NASA Astrophysics Data System (ADS)

    Panitz, J. A.; Rempfer, Gertrude

    2006-11-01

    A simple transmission electron microscope (TEM) suitable for lecture demonstrations is described. In this TEM electrons are created in a glow discharge between two parallel electrodes in air at a reduced pressure. The electrons are collimated by a small hole in the anode, focused by a solenoid that acts as an electromagnetic lens, and imaged on a thin layer of phosphor deposited inside an Erlenmeyer flask. An image of a biological sample placed between the source and the lens can be magnified about 20 times. The microscope uses inexpensive components that can be quickly assembled during a demonstration. The TEM provides a visual and memorable display that highlights phenomena such as mean-free-path, charged particle optics, electrical discharges, and cathodoluminescence.

  13. 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.

  14. 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.

  15. 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.

  16. Science 101: How Does an Electron Microscope Work?

    ERIC Educational Resources Information Center

    Robertson, Bill

    2013-01-01

    Contrary to popular opinion, electron microscopes are not used to look at electrons. They are used to look for structure in things that are too small to observe with an optical microscope, or to obtain images that are magnified much more than is obtainable with an optical microscope. To understand how electron microscopes work, it will help to go…

  17. Science 101: How Does an Electron Microscope Work?

    ERIC Educational Resources Information Center

    Robertson, Bill

    2013-01-01

    Contrary to popular opinion, electron microscopes are not used to look at electrons. They are used to look for structure in things that are too small to observe with an optical microscope, or to obtain images that are magnified much more than is obtainable with an optical microscope. To understand how electron microscopes work, it will help to go…

  18. Transmission electron microscopic pathoanatomy of congenital trigger thumb.

    PubMed

    Buchman, M T; Gibson, T W; McCallum, D; Cuda, D D; Ramos, A G

    1999-01-01

    Previous studies of trigger digits in children have been limited to gross morphology and light-microscopic histology. Nine children with 11 trigger thumbs formed a preliminary study group for electron-microscopic evaluation of tendon nodules and A-1 pulleys. This pathoanatomic investigation was not previously reported. Comparison was made with light-microscopic sections. Large amounts of mature collagen was observed. Fibroblasts with prominent rough endoplasmic reticulum were present. No degenerative or inflammatory changes were noted in either tendon or sheath. We believe that although the etiology of trigger digits is still uncertain, an infectious, inflammatory, or degenerative process is unlikely.

  19. Ultrafast supercontinuum fiber-laser based pump-probe scanning magneto-optical Kerr effect microscope for the investigation of electron spin dynamics in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution

    SciTech Connect

    Henn, T.; Kiessling, T. Ossau, W.; Molenkamp, L. W.; Biermann, K.; Santos, P. V.

    2013-12-15

    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 the 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.

  20. 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).

  1. 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).

  2. Applications of 1 MV field-emission transmission electron microscope.

    PubMed

    Tonomura, Akira

    2003-01-01

    A newly developed 1 MV field-emission transmission electron microscope has recently been applied to the field of superconductivity by utilizing its bright and monochromatic field-emission electron beam. This microscope allows individual magnetic vortices inside high-Tc superconductors to be observed, thus, opening the way to investigate the unusual behaviour of vortices, which reflects the anisotropic layered structure of these superconducting materials. One example is the observation of the arrangements of chain vortex lines that are formed when a magnetic field is applied obliquely to the layer plane of the materials.

  3. [Scanning electron microscopic investigations of cutting edge quality in lamellar keratotomy using the Wavelight femtosecond laser (FS-200) : What influence do spot distance and an additional tunnel have?

    PubMed

    Hammer, T; Höche, T; Heichel, J

    2017-07-24

    Femtosecond lasers (fs-lasers) are established cutting instruments for the creation of LASIK flaps. Previous studies often showed even rougher surfaces after application of fs-laser systems compared to lamellar keratotomy with mechanical microkeratomes. When cutting the cornea with fs-lasers, an intrastromal gas development occurs, which has a potentially negative influence on the cutting quality if the gas cannot be dissipated; therefore, manufacturers have chosen the way of gas assimilation in so-called pockets. The investigated system creates a tunnel which opens under the conjunctiva. The aim of this study was to investigate the effects of a tunnel as well as the influence of different spot distances on the quality of cut surfaces and edges. In this experimental study on freshly enucleated porcine eyes (n = 15), the following cuts were carried out with the FS-200 (Wavelight, Erlangen, Germany): 1. standard setting (spot and line separation 8 µm), 2. with tunnel for gas drainage, 3. without gas-conducting tunnel, 4. with increased spot spacing (spot and line separation 9 μm instead of 8 μm) and 5. with reduced spot spacing (spot and line separation 7 μm instead of 8 μm). Subsequently, scanning electron microscopy (FEI Quanta 650, Hillsboro, OR) of the cut edges and surfaces as well as the gas drain tunnel were performed. The evaluation was based on an established score. The current fs-laser system (200 Hz) is able to create smooth cutting surfaces and sharp edges. The changed density of laser pulses compared to the standard settings with a reduced or increased distance between the pulses, did not achieve any further improvement in the surface quality. The gas-conducting tunnel could be detected by scanning electron microscope. In the case of cutting without a tunnel, roughened surfaces and irregularities on the cutting edges were found. When the FS-200 fs-laser is used, LASIK cuts with very smooth cut surfaces and sharp cutting

  4. Phagocytosis of bacteria by polymorphonuclear leukocytes: a freeze-fracture, scanning electron microscope, and thin-section investigation of membrane structure

    PubMed Central

    Moore, PL; Bank, HL; Brissie, NT; Spicer, SS

    1978-01-01

    The changes in membrane structure of rabbit polymorphonuclear (PMN) leukocytes during bacterial phagocytosis was investigated with scanning electron microscope (SEM), thin-section, and freeze-fracture techniques. SEM observations of bacterial attachment sites showed the involvement of limited areas of PMN membrane surface (0.01-0.25μm(2)). Frequently, these areas of attachment were located on membrane extensions. The membrane extensions were present before, during, and after the engulfment of bacteria, but were diminished in size after bacterial engulfment. In general, the results obtained with SEM and thin-section techniques aided in the interpretation of the three-dimensional freeze-fracture replicas. Freeze-fracture results revealed the PMN leukocytes had two fracture faces as determined by the relative density of intramembranous particles (IMP). Membranous extensions of the plasma membrane, lysosomes, and phagocytic vacuoles contained IMP's with a distribution and density similar to those of the plasma membrane. During phagocytosis, IMPs within the plasma membrane did not undergo a massive aggregation. In fact, structural changes within the membranes were infrequent and localized to regions such as the attachment sites of bacteria, the fusion sites on the plasma membrane, and small scale changes in the phagocytic vacuole membrane during membrane fusion. During the formation of the phagocytic vacuole, the IMPs of the plasma membrane appeared to move in with the lipid bilayer while maintaining a distribution and density of IMPs similar to those of the plasma membranes. Occasionally, IMPs were aligned to linear arrays within phagocytic vacuole membranes. This alignment might be due to an interaction with linearly arranged motile structures on the side of the phagocytic vacuole membranes. IMP-free regions were observed after fusion of lysosomes with the phagocytic vacuoles or plasma membrane. These IMP-free areas probably represent sites where membrane fusion

  5. Spectral, electron microscopic and chemical investigations of gamma-induced purple color zonings in amethyst crystals from the Dursunbey-Balıkesir region of Turkey

    NASA Astrophysics Data System (ADS)

    Hatipoğlu, Murat; Kibar, Rana; Çetin, Ahmet; Can, Nurdoğan; Helvacı, Cahit; Derin, H.

    2011-07-01

    Amethyst crystals on matrix specimens from the Dursunbey-Balıkesir region in Turkey have five representative purple color zonings: dark purple, light purple, lilac, orchid, and violet. The purple color zonings have been analyzed with optical absorption spectra in the visible wavelength region, chemical full trace element analyses (inductively coupled plasma-atomic emission spectroscopy and inductively coupled plasma-mass spectroscopy), and scanning electron microscopic images with high magnification. It can be proposed that the production of the purple color in amethyst crystals is due to three dominant absorption bands centered at 375, 530, and 675 nm, respectively. In addition, the purple color zonings are also due to four minor absorption bands centered at 435, 480, 620, and 760 nm. X-ray diffraction graphics of the investigated amethyst crystals indicate that these crystals are composed of a nearly pure alpha-quartz phase and do not include any moganite silica phase and/or other mineral implications. Trace element analyses of the amethyst crystals show five representative purple color zonings, suggesting that the absorption bands can be mainly attributed to extrinsic defects (chemical impurities). However, another important factor that influences all structural defects in amethyst is likely to be the gamma irradiation that exists during amethyst crystallization and its inclusion in host materials. This gamma irradiation originates from the large underlying intrusive granitoid body in the region of amethyst formation. Irradiation modifies the valence values of the impurity elements in the amethyst crystals. It is observed that the violet-colored amethyst crystals have the most stable and the least reversible coloration when exposed to strong light sources. This situation can be related to the higher impurity content of Fe (2.50 ppm), Co (3.1 ppm), Ni (38 ppm), Cu (17.9 ppm), Zn (10 ppm), Zr (3.9 ppm), and Mo (21.8 ppm).

  6. Miniature electron microscope beam column optics

    NASA Astrophysics Data System (ADS)

    Loyd, Jody Stuart

    This investigation is in the area of electrostatic lens design with the overarching goal of contributing to the creation of a miniaturized scanning electron microscope (SEM) for use in mineralogical analysis or detection of signs of life on the surface of Mars. Such an instrument could also have application in the exploration of Earth's moon, planetary moons, asteroids, or comets. Other embodiments could include tabletop or field portable SEMs for use on Earth. The scope of this research is in the design of a beam column that attains focusing, demagnification, and aberration control within the smallest achievable package. The goals of planetary exploration and of spaceflight in general impose severe constraints on the instrument's mass and electrical power consumption, while favoring a robust design of small size and high rigidity that is also simple to align. To meet these requirements a design using electrostatic lenses was favored because of the lower power requirement and mass of electrostatic versus magnetic lenses, their relatively simple construction, as well as inherently easier shielding from extraneous fields. In modeling the lens field, a hybrid of a Boundary Element Method (BEM) and a Fourier series solution was employed, whereby an initial solution from the BEM is used to derive the bounding potential of a cylindrical subdomain for the subsequent Fourier series solution. The approach is applicable to many problems in physics and combines the inherent precision of this series solution with the flexibility of BEM to describe practical, non-idealized electrode shapes. The resulting lens field in the Fourier series subdomain is of higher precision, thereby allowing smaller errors in subsequent calculations of electron ray paths. The effects of aberrations are thus easier to observe in tracing non-paraxial rays. A significant speed increase in tracing rays is also observed. The modeling technique has been validated by reproducing example ray-traces through

  7. On the preparation, microscopic investigation and application of ISCOMs.

    PubMed

    Myschik, Julia; Lendemans, Dirk G; McBurney, Warren T; Demana, Patrick H; Hook, Sarah; Rades, Thomas

    2006-01-01

    ISCOM matrices constitute colloidal structures formed from Quillaja saponins, cholesterol and phospholipid. Addition of protein antigens to these matrices leads to the formation of ISCOMs. In this review we report on microscopic investigations of ISCOM matrices and ISCOMs as well as related colloidal structures, such as helices, worm-like micelles, ring-like micelles, and lamellae structures. We briefly outline the immunologic basis for the use of ISCOMs as vaccine delivery systems, and describe the various methods to form ISCOMs. Negative staining transmission electron micrographs of all colloidal structures are presented and described. On the basis of our microscopic investigations, different formation mechanisms of ISCOMS are discussed.

  8. Investigation of Fretting by Microscopic Observation

    NASA Technical Reports Server (NTRS)

    Godfrey, Douglas

    1951-01-01

    An experimental investigation, using microscopic observation and color motion photomicrographs of the action, was conducted to determine the cause of fretting. Glass and other noncorrosive materials, as well as metals, were used as specimens. A very simple apparatus vibrated convex surfaces in contact with stationary flat surfaces at frequencies of 120 cycles or less than l cycle per second, an amplitude of 0.0001 inch, and load of 0.2 pound.

  9. Development of electron moire method using a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Kishimoto, Satoshi; Egashira, Mitsuru; Shinya, Norio

    1991-12-01

    A new moire method using a scanning electron microscope (SEM) for the measurement of micro-deformation has been developed. This new method makes it possible to observe the moire fringe pattern and SEM image at the same time. In this method, a fine microgrid prepared by electron lithography is used as a model grid, and scanning exposure of the electron beam in a SEM is used as a master grid. The exposure of electron beam on the specimen with the model grid produces moire fringes of bright and dark lines formed by the different amount of the secondary electrons. This fine moire fringe pattern is fine and clear enough to measure the strain distribution in a small area. By this method, concentrated strains around a small hole in polyimide resin specimens and also the inhomogeneous micro- deformations such as grain boundary sliding in copper specimens were measured, with high accuracy.

  10. Electron microscope evidence of virus infection in cultured marine fish

    NASA Astrophysics Data System (ADS)

    Sun, Xiu-Qin; Zhang, Jin-Xing; Qu, Ling-Yun

    2000-09-01

    Electron microscope investigation on the red sea bream ( Pagrosomus major), bastard halibut ( Paralichthys olivaceus) and stone flounder ( Kareius bicoloratus) in North China revealed virus infection in the bodies of the dead and diseased fish. These viruses included the lymphocystis disease virus (LDV), parvovirus, globular virus, and a kind of baculavirus which was not discovered and reported before and is now tentatively named baculavirus of stone flounder ( Kareius bicoloratus).

  11. 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.

  12. Observation of a vacuum tunnel gap in a transmission electron microscope using a micromechanical tunneling microscope

    NASA Astrophysics Data System (ADS)

    Lutwyche, M. I.; Wada, Y.

    1995-05-01

    This letter reports the observation of the vacuum tunnel gap between two conductors using a high resolution transmission electron microscope. A 2.5 mm square micromachined tunneling microscope chip has been fabricated with a minimum feature size of 0.4 μm. The chip fits into a modified side-entry type transmission electron microscope holder. The tunnel gap is controlled by a purpose-built feedback controller. The micromachines work reliably during observation of the tip apex in a transmission electron microscope, allowing the voltage and current to be changed while the tunnel gap is observed.

  13. TEBAL: Nanosculpting devices with electrons in a transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Drndic, Marija

    2008-03-01

    Manipulation of matter on the scale of atoms and molecules is an essential part of realizing the potential that nanotechnology has to offer. In this talk I will describe transmission electron beam ablation lithography (TEBAL), a method for fabricating nanostructures and fully integrated devices on silicon nitride membranes by nanosculpting evaporated metal films with electron beams. TEBAL works by controllably exposing materials to an intense and highly focused beam of 200 keV electrons inside the transmission electron microscope (TEM). The effect of electron irradiation can be used to controllably displace or ablate regions of the metal with resolution on the scale of tens of atoms per exposure. In situ TEM imaging of the ablation action with atomic resolution allows for real-time feedback control during fabrication. Specific examples presented here include the fabrication and characterization of nanogaps, nanorings, nanowires with tailored shapes and curvatures, and multi-terminal devices with nanoislands or nanopores between the terminals. These nanostructures are fabricated at precise locations on a chip and seamlessly integrated into large-scale circuitry. I will discuss how the combination of high resolution, geometrical control and yield make TEBAL attractive for many applications including nanoelectronics, superconductivity, nanofluidics and molecular (DNA) translocation studies through nanopore-based transistors. References: 1) M.D. Fischbein and M. Drndic, ``Sub-10 nm Device Fabrication in a Transmission Electron Microscope'', Nano Letters, 7 (5), 1329, 2007. 2) M. D. Fischbein and M. Drndic, ``Nanogaps by direct lithography for high-resolution imaging and electronic characterization of nanostructures'', Applied Physics Letters, 88 (6), 063116, 2006.

  14. Binding of the transcription activator NRI (NTRC) to a supercoiled DNA segment imitates association with the natural enhancer: an electron microscopic investigation.

    PubMed Central

    Révet, B; Brahms, S; Brahms, G

    1995-01-01

    Electron microscopic visualization indicates that the transcription activator NRI (NTRC) binds with exceptional selectivity and efficiency to a sequence-induced superhelical (spiral) segment inserted upstream of the glnA promoter, accounting for its observed ability to substitute for the natural glnA enhancer. The cooperative binding of NRI to the spiral insert leads to protein oligomerization which, at higher concentration, promotes selective coating of the entire superhelical segment with protein. Localization of NRI at apical loops is observed with negatively supercoiled plasmid DNA. With a linear plasmid, bending of DNA is observed. We confirm that NRI is a DNA-bending protein, consistent with its high affinity for spiral DNA. These results prove that spiral DNA without any homology to the NRI-binding sequence site can substitute for the glnA enhancer by promoting cooperative activator binding to DNA and facilitating protein oligomerization. Similar mechanisms might apply to other prokaryotic and eukaryotic activator proteins that share the ability to bend DNA and act efficiently as multimers. Images Fig. 1 Fig. 2 Fig. 4 Fig. 5 PMID:7638226

  15. Collection of secondary electrons in scanning electron microscopes.

    PubMed

    Müllerová, I; Konvalina, I

    2009-12-01

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

  16. Microscopic Investigations into the Effect of Surface Treatment of Cathode and Electron Transport Layer on the Performance of Inverted Organic Solar Cells.

    PubMed

    Gupta, Shailendra Kumar; Jindal, Rajeev; Garg, Ashish

    2015-08-05

    Surface treatments of various layers in organic solar cells play a vital role in determining device characteristics. In this manuscript, we report on the influence of surface treatment of indium tin oxide (ITO) electrode and electron transport layer (ETL), ZnO, on the photovoltaic performance of inverted organic solar cells (IOSC) and their correlation with the surface chemistry and surface potential as studied using X-ray photoelectron spectroscopy (XPS) and Kelvin probe force microscopy (KPFM), using the device structure glass/ITO/ZnO/P3HT: PCBM/MoO3/(Au or Ag) (P3HT, poly(3-hexylthiophene-2,5-diyl), and PCBM, phenyl-C61-butyric acid methyl ester). Our results show that although ozonization of ITO leads to an improvement in the device power conversion efficiency, the ozonization of a subsequent ZnO layer results in a decreased performance mainly because of a decrease in the fill factor (FF). However, subsequent methanol (CH3OH) treatment of ZnO layer on an ozonized ITO electrode shows substantial improvement with device efficiencies exceeding ∼4% along with superior reproducibility of the devices. Furthermore, a detailed analysis of the surface wettability, chemistry, and surface potential using contact angle measurements, XPS, and KPFM attribute the improvements to the elimination of surface defects and the changes in the surface potential. Finally, impedance analysis suggests that methanol treatment of the ZnO layers leads to the development of a favorable nanophase structure with higher conductivity, which is otherwise indiscernible using microscopic methods.

  17. A sub-cm micromachined electron microscope

    NASA Technical Reports Server (NTRS)

    Feinerman, A. D.; Crewe, D. A.; Perng, D. C.; Shoaf, S. E.; Crewe, A. V.

    1993-01-01

    A new approach for fabricating macroscopic (approximately 10x10x10 mm(exp 3)) structures with micron accuracy has been developed. This approach combines the precision of semiconductor processing and fiber optic technologies. A (100) silicon wafer is anisotropically etched to create four orthogonal v-grooves and an aperture on each 10x12 mm die. Precision 308 micron optical fibers are sandwiched between the die to align the v-grooves. The fiber is then anodically bonded to the die above and below it. This procedure is repeated to create thick structures and a stack of 5 or 6 die will be used to create a miniature scanning electron microscope (MSEM). Two die in the structure will have a segmented electrode to deflect the beam and correct for astigmatism. The entire structure is UHV compatible. The performance of an SEM improves as its length is reduced and a sub-cm 2 keV MSEM with a field emission source should have approximately 1 nm resolution. A low voltage high resolution MSEM would be useful for the examination of biological specimens and semiconductors with a minimum of damage. The first MSEM will be tested with existing 6 micron thermionic sources. In the future a micromachined field emission source will be used. The stacking technology presented in this paper can produce an array of MSEMs 1 to 30 mm in length with a 1 mm or larger period. A key question being addressed by this research is the optimum size for a low voltage MSEM which will be determined by the required spatial resolution, field of view, and working distance.

  18. Scanning Electron Microscope Studies on Aggregation Characteristics of Alumina Nanofluids

    DTIC Science & Technology

    2013-08-01

    UNCLASSIFIED SCANNING ELECTRON MICROSCOPE STUDIES ON AGGREGATION CHARACTERISTICS OF ALUMINA NANOFLUIDS INTERIM REPORT TFLRF No. 443...UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED SCANNING ELECTRON MICROSCOPE STUDIES ON AGGREGATION CHARACTERISTICS OF ALUMINA NANOFLUIDS INTERIM REPORT TFLRF...Aggregation Characteristics of Alumina Nanofluids 5a. CONTRACT NUMBER W56HZV-09-C-0100 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S

  19. Dynamic-scanning-electron-microscope study of friction and wear

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

    A friction and wear apparatus was built into a real time scanning electron microscope (SEM). The apparatus and SEM comprise a system which provides the capability of performing dynamic friction and wear experiments in situ. When the system is used in conjunction with dispersive X-ray analysis, a wide range of information on the wearing process can be obtained. The type of wear and variation with speed, load, and time can be investigated. The source, size, and distribution of wear particles can be determined and metallic transferal observed. Some typical results obtained with aluminum, copper, and iron specimens are given.

  20. A high-resolution field-emission-gun, scanning electron microscope investigation of anisotropic hydrogen decrepitation in Nd-Fe-B-based sintered magnets

    NASA Astrophysics Data System (ADS)

    Soderznik, Marko; McGuiness, Paul; Zuzek-Rozman, Kristina; Škulj, Irena; Yan, Gaolin; Kobe, Spomenka

    2010-05-01

    In this investigation commercial magnets based on (Nd,Dy)14(Fe,Co)79B7 were prepared by a conventional powder-metallurgy route with a degree of alignment equal to ˜90% and then exposed to hydrogen at a pressure of 1 bar. The magnets, in the form of cylinders, were observed to decrepitate exclusively from the ends. High-resolution electron microscopy was able to identify the presence of crack formation within the Nd2Fe14B grains, with the cracks running parallel to the c axis of these grains. Based on the concentration profile for hydrogen in a rare-earth transition-metal material, it is clear that the presence of hydrogen-induced cracks running perpendicular to the ends of the magnet provides for a much more rapidly progressing hydrogen front in this direction than from the sides of the magnet. This results in the magnet exhibiting a macroscopic tendency to decrepitate from the poles of the magnet toward the center. This combination of microstructural modification via particle alignment as part of the sintering process and direct observation via high-resolution electron microscopy has led to a satisfying explanation for the anisotropic hydrogen-decrepitation effect.

  1. Analytical electron microscope study of eight ataxites

    NASA Technical Reports Server (NTRS)

    Novotny, P. M.; Goldstein, J. I.; Williams, D. B.

    1982-01-01

    Optical and electron optical (SEM, TEM, AEM) techniques were employed to investigate the fine structure of eight ataxite-iron meteorites. Structural studies indicated that the ataxites can be divided into two groups: a Widmanstaetten decomposition group and a martensite decomposition group. The Widmanstaetten decomposition group has a Type I plessite microstructure and the central taenite regions contain highly dislocated lath martensite. The steep M shaped Ni gradients in the taenite are consistent with the fast cooling rates, of not less than 500 C/my, observed for this group. The martensite decomposition group has a Type III plessite microstructure and contains all the chemical group IVB ataxites. The maximum taenite Ni contents vary from 47.5 to 52.7 wt % and are consistent with slow cooling to low temperatures of not greater than 350 C at cooling rates of not greater than 25 C/my.

  2. Analytical electron microscope study of eight ataxites

    NASA Astrophysics Data System (ADS)

    Novotny, P. M.; Goldstein, J. I.; Williams, D. B.

    1982-12-01

    Optical and electron optical (SEM, TEM, AEM) techniques were employed to investigate the fine structure of eight ataxite-iron meteorites. Structural studies indicated that the ataxites can be divided into two groups: a Widmanstaetten decomposition group and a martensite decomposition group. The Widmanstaetten decomposition group has a Type I plessite microstructure and the central taenite regions contain highly dislocated lath martensite. The steep M shaped Ni gradients in the taenite are consistent with the fast cooling rates, of not less than 500 C/my, observed for this group. The martensite decomposition group has a Type III plessite microstructure and contains all the chemical group IVB ataxites. The maximum taenite Ni contents vary from 47.5 to 52.7 wt % and are consistent with slow cooling to low temperatures of not greater than 350 C at cooling rates of not greater than 25 C/my.

  3. 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.

  4. The Scanning Electron Microscope and the Archaeologist

    ERIC Educational Resources Information Center

    Ponting, Matthew

    2004-01-01

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

  5. The Scanning Electron Microscope and the Archaeologist

    ERIC Educational Resources Information Center

    Ponting, Matthew

    2004-01-01

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

  6. Ultra low-K shrinkage behavior when under electron beam in a scanning electron microscope

    SciTech Connect

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

    2013-08-28

    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, with a densification of the layer and a loss of carbon and hydrogen elements being observed.

  7. 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.

  8. 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.

  9. Electric field stimulation setup for photoemission electron microscopes

    SciTech Connect

    Buzzi, M.; Vaz, C. A. F.; Raabe, J.; Nolting, F.

    2015-08-15

    Manipulating magnetisation by the application of an electric field in magnetoelectric multiferroics represents a timely issue due to the potential applications in low power electronics and the novel physics involved. Thanks to its element sensitivity and high spatial resolution, X-ray photoemission electron microscopy is a uniquely suited technique for the investigation of magnetoelectric coupling in multiferroic materials. In this work, we present a setup that allows for the application of in situ electric and magnetic fields while the sample is analysed in the microscope. As an example of the performances of the setup, we present measurements on Ni/Pb(Mg{sub 0.66}Nb{sub 0.33})O{sub 3}-PbTiO{sub 3} and La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/PMN-PT artificial multiferroic nanostructures.

  10. Electric field stimulation setup for photoemission electron microscopes.

    PubMed

    Buzzi, M; Vaz, C A F; Raabe, J; Nolting, F

    2015-08-01

    Manipulating magnetisation by the application of an electric field in magnetoelectric multiferroics represents a timely issue due to the potential applications in low power electronics and the novel physics involved. Thanks to its element sensitivity and high spatial resolution, X-ray photoemission electron microscopy is a uniquely suited technique for the investigation of magnetoelectric coupling in multiferroic materials. In this work, we present a setup that allows for the application of in situ electric and magnetic fields while the sample is analysed in the microscope. As an example of the performances of the setup, we present measurements on Ni/Pb(Mg(0.66)Nb(0.33))O3-PbTiO3 and La(0.7)Sr(0.3)MnO3/PMN-PT artificial multiferroic nanostructures.

  11. Electric field stimulation setup for photoemission electron microscopes

    NASA Astrophysics Data System (ADS)

    Buzzi, M.; Vaz, C. A. F.; Raabe, J.; Nolting, F.

    2015-08-01

    Manipulating magnetisation by the application of an electric field in magnetoelectric multiferroics represents a timely issue due to the potential applications in low power electronics and the novel physics involved. Thanks to its element sensitivity and high spatial resolution, X-ray photoemission electron microscopy is a uniquely suited technique for the investigation of magnetoelectric coupling in multiferroic materials. In this work, we present a setup that allows for the application of in situ electric and magnetic fields while the sample is analysed in the microscope. As an example of the performances of the setup, we present measurements on Ni/Pb(Mg0.66Nb0.33)O3-PbTiO3 and La0.7Sr0.3MnO3/PMN-PT artificial multiferroic nanostructures.

  12. Coherent Chromatic Effect in the Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Erni, Rolf

    2016-03-01

    Under the assumption of local atomic scattering, elastic electron scattering at finite scattering angles implies a small but finite energy loss. This energy loss, which under conventional imaging conditions in high-resolution transmission electron microscopy is of the order of 0.1 meV and thus negligible, increases by more than 2 orders of magnitude if light elements are investigated at sub-Ångström resolution. For a microscope of finite chromatic aberration, the energy loss leads to an element-specific chromatic effect which increases with the instrument resolution and with decreasing mass of the scattering atom. Despite that this effect is small, it can degrade the achievable image contrast. However, the effect can be considered in the optimization of the phase-contrast imaging conditions and even be beneficial to enhance the relative image contrast of light atoms in the presence of heavy atoms.

  13. Coherent Chromatic Effect in the Transmission Electron Microscope.

    PubMed

    Erni, Rolf

    2016-03-18

    Under the assumption of local atomic scattering, elastic electron scattering at finite scattering angles implies a small but finite energy loss. This energy loss, which under conventional imaging conditions in high-resolution transmission electron microscopy is of the order of 0.1 meV and thus negligible, increases by more than 2 orders of magnitude if light elements are investigated at sub-Ångström resolution. For a microscope of finite chromatic aberration, the energy loss leads to an element-specific chromatic effect which increases with the instrument resolution and with decreasing mass of the scattering atom. Despite that this effect is small, it can degrade the achievable image contrast. However, the effect can be considered in the optimization of the phase-contrast imaging conditions and even be beneficial to enhance the relative image contrast of light atoms in the presence of heavy atoms.

  14. Quantification of the Information Limit of Transmission Electron Microscopes

    SciTech Connect

    Barthel, J.; Thust, A.

    2008-11-14

    The resolving power of high-resolution transmission electron microscopes is characterized by the information limit, which reflects the size of the smallest object detail observable with a particular instrument. We introduce a highly accurate measurement method for the information limit, which is suitable for modern aberration-corrected electron microscopes. An experimental comparison with the traditionally applied Young's fringe method yields severe discrepancies and confirms theoretical considerations according to which the Young's fringe method does not reveal the information limit.

  15. 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.

  16. In situ formation of bismuth nanoparticles through electron-beam irradiation in a transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Sepulveda-Guzman, S.; Elizondo-Villarreal, N.; Ferrer, D.; Torres-Castro, A.; Gao, X.; Zhou, J. P.; Jose-Yacaman, M.

    2007-08-01

    In this work, bismuth nanoparticles were synthesized when a precursor, sodium bismuthate, was exposed to an electron beam at room temperature in a transmission electron microscope (TEM). The irradiation effects were investigated in situ using selected-area electron diffraction, high-resolution transmission electron microscopy and x-ray energy dispersive spectroscopy. After the electron irradiation, bismuth nanoparticles with a rhombohedral structure and diameter of 6 nm were observed. The average particle size increased with the irradiation time. The electron-induced reduction is attributed to the desorption of oxygen ions. This method offers a one-step route to synthesize bismuth nanoparticles using electron irradiation, and the particle size can be controlled by the irradiation time.

  17. The evolution of ultrafast electron microscope instrumentation.

    PubMed

    Reed, B W; Armstrong, M R; Browning, N D; Campbell, G H; Evans, J E; LaGrange, T; Masiel, D J

    2009-08-01

    Extrapolating from a brief survey of the literature, we outline a vision for the future development of time-resolved electron probe instruments that could offer levels of performance and flexibility that push the limits of physical possibility. This includes a discussion of the electron beam parameters (brightness and emittance) that limit performance, the identification of a dimensionless invariant figure of merit for pulsed electron guns (the number of electrons per lateral coherence area, per pulse), and calculations of how this figure of merit determines the trade-off of spatial against temporal resolution for different imaging modes. Modern photonics' ability to control its fundamental particles at the quantum level, while enjoying extreme flexibility and a very large variety of operating modes, is held up as an example and a goal. We argue that this goal may be approached by combining ideas already in the literature, suggesting the need for large-scale collaborative development of next-generation time-resolved instruments.

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

    PubMed

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

    1992-05-01

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

  19. Microscope spectrometer for light scattering investigations

    SciTech Connect

    Barbara, Aude; Lopez-Rios, Tomas; Dumont, Sylvain; Gay, Frederic; Quemerais, Pascal

    2010-08-01

    We describe a setup including a microscope to study volumes of a few {mu}m{sup 3} by static and dynamic light scattering (DLS) in a backscattering configuration. Light scattered by individual objects of micrometric size can be analyzed in the 400-800 nm spectral range. This setup can also be employed to study both diluted and concentrated colloidal solutions by DLS measurements. For diluted solutions we found evidence of the fluctuations of the number of particles in a confocal volume. We discuss their contribution to the autocorrelation function of the scattered intensity measured as a function of time.

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1992-12-01

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

  2. Simulation and Characterization of a Miniaturized Scanning Electron Microscope

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  3. Electron microscopic observations of human hair medulla.

    PubMed

    de Cássia Comis Wagner, Rita; Kiyohara, Pedro Kunihiko; Silveira, Marina; Joekes, Inés

    2007-04-01

    In the study of human hair, medulla is the less studied structure because it is believed that it has no influence on the fibre properties. The aim of this paper is to contribute to the better understanding of medulla morphology. Using reproducible methods for hair samples preparations allowed observing the inner fibre by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Three medulla subunits were observed in cryofractured samples. In addition, the application of plasma etching on samples allowed accessing chemical differences between them. Two kinds of medulla were identified using stereomicroscopy: thin and thick medulla. They were morphologically differentiated using TEM. These methods can be used to study systematically the effects of medulla on hair properties and to evaluate the efficiency of cosmetic products.

  4. Electron Microscope Studies of Cadmium Mercury Telluride

    NASA Astrophysics Data System (ADS)

    Lyster, Martin

    Available from UMI in association with The British Library. Requires signed TDF. Epitaxial layers of Cd_{x }Hg_{(1-x)}Te grown on various substrates by liquid phase epitaxy and metallo-organic vapour phase epitaxy have been studied using transmission and scanning electron microscopy, in a variety of contrast modes. Wavelength-dispersive X-ray microanalysis has been used to study interfaces in epitaxial specimens, and the results are used to derive diffusion coefficients for a range of values of x in Cd_ {x}Hg_{(1-x)} Te. Extensive use has been made of back-scattered electron contrast in the SEM as a means of compositional mapping, and defect structures are imaged by this technique. The back-scattered electron contrast at interfaces has been studied in detail and is modelled using the Monte Carlo approach. The modelling is combined with calculations and practical measurements of the probe size in the SEM instrument used in the work, to arrive at a quantitative explanation of this contrast. The SEM and scintillator detector used allow a spatial resolution of better than 1000A, but it is shown that improvements in this are possible with present technology. Scanning infra-red microscopy (SIRM) and high -resolution transmission electron microscopy (HREM) have been applied to the study of CdTe. SIRM images reveal information about Te precipitation, including particle size and density. HREM images provide results concerning dislocation structures in CdTe. Selected-area diffraction contrast TEM results are presented which illustrate the microstructure of LPE and MOVPE material; and TEM foil preparation techniques are discussed, including the choice of ion species for milling cross-sectional specimens. In view of the results obtained, suggestions are made for future work in this field.

  5. Influence of mechanical noise inside a scanning electron microscope

    SciTech Connect

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

    2015-04-15

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

  6. 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.

  7. Dynamics of a nanodroplet under a transmission electron microscope

    SciTech Connect

    Leong, Fong Yew; Mirsaidov, Utkur M.; Matsudaira, Paul; Mahadevan, L.

    2014-01-15

    We investigate the cyclical stick-slip motion of water nanodroplets on a hydrophilic substrate viewed with and stimulated by a transmission electron microscope. Using a continuum long wave theory, we show how the electrostatic stress imposed by non-uniform charge distribution causes a pinned convex drop to deform into a toroidal shape, with the shape characterized by the competition between the electrostatic stress and the surface tension of the drop, as well as the charge density distribution which follows a Poisson equation. A horizontal gradient in the charge density creates a lateral driving force, which when sufficiently large, overcomes the pinning induced by surface heterogeneities in the substrate disjoining pressure, causing the drop to slide on the substrate via a cyclical stick-slip motion. Our model predicts step-like dynamics in drop displacement and surface area jumps, qualitatively consistent with experimental observations.

  8. Fully Mechanically Controlled Automated Electron Microscopic Tomography

    PubMed Central

    Liu, Jinxin; Li, Hongchang; Zhang, Lei; Rames, Matthew; Zhang, Meng; Yu, Yadong; Peng, Bo; Celis, César Díaz; Xu, April; Zou, Qin; Yang, Xu; Chen, Xuefeng; Ren, Gang

    2016-01-01

    Knowledge of three-dimensional (3D) structures of each individual particles of asymmetric and flexible proteins is essential in understanding those proteins’ functions; but their structures are difficult to determine. Electron tomography (ET) provides a tool for imaging a single and unique biological object from a series of tilted angles, but it is challenging to image a single protein for three-dimensional (3D) reconstruction due to the imperfect mechanical control capability of the specimen goniometer under both a medium to high magnification (approximately 50,000–160,000×) and an optimized beam coherence condition. Here, we report a fully mechanical control method for automating ET data acquisition without using beam tilt/shift processes. This method could reduce the accumulation of beam tilt/shift that used to compensate the error from the mechanical control, but downgraded the beam coherence. Our method was developed by minimizing the error of the target object center during the tilting process through a closed-loop proportional-integral (PI) control algorithm. The validations by both negative staining (NS) and cryo-electron microscopy (cryo-EM) suggest that this method has a comparable capability to other ET methods in tracking target proteins while maintaining optimized beam coherence conditions for imaging. PMID:27403922

  9. Fully Mechanically Controlled Automated Electron Microscopic Tomography.

    PubMed

    Liu, Jinxin; Li, Hongchang; Zhang, Lei; Rames, Matthew; Zhang, Meng; Yu, Yadong; Peng, Bo; Celis, César Díaz; Xu, April; Zou, Qin; Yang, Xu; Chen, Xuefeng; Ren, Gang

    2016-07-11

    Knowledge of three-dimensional (3D) structures of each individual particles of asymmetric and flexible proteins is essential in understanding those proteins' functions; but their structures are difficult to determine. Electron tomography (ET) provides a tool for imaging a single and unique biological object from a series of tilted angles, but it is challenging to image a single protein for three-dimensional (3D) reconstruction due to the imperfect mechanical control capability of the specimen goniometer under both a medium to high magnification (approximately 50,000-160,000×) and an optimized beam coherence condition. Here, we report a fully mechanical control method for automating ET data acquisition without using beam tilt/shift processes. This method could reduce the accumulation of beam tilt/shift that used to compensate the error from the mechanical control, but downgraded the beam coherence. Our method was developed by minimizing the error of the target object center during the tilting process through a closed-loop proportional-integral (PI) control algorithm. The validations by both negative staining (NS) and cryo-electron microscopy (cryo-EM) suggest that this method has a comparable capability to other ET methods in tracking target proteins while maintaining optimized beam coherence conditions for imaging.

  10. Experimental charge density from electron microscopic maps.

    PubMed

    Wang, Jimin

    2017-08-01

    The charge density (CD) distribution of an atom is the difference per unit volume between the positive charge of its nucleus and the distribution of the negative charges carried by the electrons that are associated with it. The CDs of the atoms in macromolecules are responsible for their electrostatic potential (ESP) distributions, which can now be visualized using cryo-electron microscopy at high resolution. CD maps can be recovered from experimental ESP density maps using the negative Laplacian operation. CD maps are easier to interpret than ESP maps because they are less sensitive to long-range electrostatic effects. An ESP-to-CD conversion involves multiplication of amplitudes of structure factors as Fourier transforms of these maps in reciprocal space by 1/d(2) , where d is the resolution of reflections. In principle, it should be possible to determine the charges carried by the individual atoms in macromolecules by comparing experimental CD maps with experimental ESP maps. © 2017 The Protein Society.

  11. Fully Mechanically Controlled Automated Electron Microscopic Tomography

    DOE PAGES

    Liu, Jinxin; Li, Hongchang; Zhang, Lei; ...

    2016-07-11

    Knowledge of three-dimensional (3D) structures of each individual particles of asymmetric and flexible proteins is essential in understanding those proteins' functions; but their structures are difficult to determine. Electron tomography (ET) provides a tool for imaging a single and unique biological object from a series of tilted angles, but it is challenging to image a single protein for three-dimensional (3D) reconstruction due to the imperfect mechanical control capability of the specimen goniometer under both a medium to high magnification (approximately 50,000-160,000×) and an optimized beam coherence condition. Here, we report a fully mechanical control method for automating ET data acquisitionmore » without using beam tilt/shift processes. This method could reduce the accumulation of beam tilt/shift that used to compensate the error from the mechanical control, but downgraded the beam coherence. Our method was developed by minimizing the error of the target object center during the tilting process through a closed-loop proportional-integral (PI) control algorithm. The validations by both negative staining (NS) and cryo-electron microscopy (cryo-EM) suggest that this method has a comparable capability to other ET methods in tracking target proteins while maintaining optimized beam coherence conditions for imaging.« less

  12. Fully Mechanically Controlled Automated Electron Microscopic Tomography

    SciTech Connect

    Liu, Jinxin; Li, Hongchang; Zhang, Lei; Rames, Matthew; Zhang, Meng; Yu, Yadong; Peng, Bo; Celis, César Díaz; Xu, April; Zou, Qin; Yang, Xu; Chen, Xuefeng; Ren, Gang

    2016-07-11

    Knowledge of three-dimensional (3D) structures of each individual particles of asymmetric and flexible proteins is essential in understanding those proteins' functions; but their structures are difficult to determine. Electron tomography (ET) provides a tool for imaging a single and unique biological object from a series of tilted angles, but it is challenging to image a single protein for three-dimensional (3D) reconstruction due to the imperfect mechanical control capability of the specimen goniometer under both a medium to high magnification (approximately 50,000-160,000×) and an optimized beam coherence condition. Here, we report a fully mechanical control method for automating ET data acquisition without using beam tilt/shift processes. This method could reduce the accumulation of beam tilt/shift that used to compensate the error from the mechanical control, but downgraded the beam coherence. Our method was developed by minimizing the error of the target object center during the tilting process through a closed-loop proportional-integral (PI) control algorithm. The validations by both negative staining (NS) and cryo-electron microscopy (cryo-EM) suggest that this method has a comparable capability to other ET methods in tracking target proteins while maintaining optimized beam coherence conditions for imaging.

  13. Fully Mechanically Controlled Automated Electron Microscopic Tomography

    NASA Astrophysics Data System (ADS)

    Liu, Jinxin; Li, Hongchang; Zhang, Lei; Rames, Matthew; Zhang, Meng; Yu, Yadong; Peng, Bo; Celis, César Díaz; Xu, April; Zou, Qin; Yang, Xu; Chen, Xuefeng; Ren, Gang

    2016-07-01

    Knowledge of three-dimensional (3D) structures of each individual particles of asymmetric and flexible proteins is essential in understanding those proteins’ functions; but their structures are difficult to determine. Electron tomography (ET) provides a tool for imaging a single and unique biological object from a series of tilted angles, but it is challenging to image a single protein for three-dimensional (3D) reconstruction due to the imperfect mechanical control capability of the specimen goniometer under both a medium to high magnification (approximately 50,000–160,000×) and an optimized beam coherence condition. Here, we report a fully mechanical control method for automating ET data acquisition without using beam tilt/shift processes. This method could reduce the accumulation of beam tilt/shift that used to compensate the error from the mechanical control, but downgraded the beam coherence. Our method was developed by minimizing the error of the target object center during the tilting process through a closed-loop proportional-integral (PI) control algorithm. The validations by both negative staining (NS) and cryo-electron microscopy (cryo-EM) suggest that this method has a comparable capability to other ET methods in tracking target proteins while maintaining optimized beam coherence conditions for imaging.

  14. Microscopic and electronic structure of semimetallic Sb and Semiconducting AlSb fabricated by nanoscale electrodeposition: An in situ scanning probe investigation.

    PubMed

    Mann, O; Aravinda, C L; Freyland, W

    2006-11-02

    The nanoscale electrocrystallization of pure Sb and the compound semiconductor AlSb on Au(111) has been studied by in situ scanning probe techniques (STM and STS) employing an ionic liquid electrolyte, {AlCl3-[C4mim]+Cl-} (1:1) containing SbCl3. The characteristic changes of the electronic structures with varying potentials have been probed for the first time by normalized differential conductance spectra, (dI/dU)/(I/U). In the underpotential deposition range of Sb the formation of two layers is observed. For the first monolayer a (square root 3 x square root 3)R30 degrees structure is determined from atomically resolved STM images. During the deposition and dissolution of the Sb monolayers characteristic wormlike or spinodal structures appear indicating surface alloying of antimony with the gold substrate. Under overpotential conditions two different Sb structures have been observed. If the deposition potential is continuously stepped to -0.1 V, Sb nanostripes form. On the other hand, randomly dispersed small clusters occur if the potential is jumped from 0.0 to -0.3 V vs Al/Al(III). Both modifications exhibit typical semimetallic behavior as shown by the STS spectra. At -1.1 V the cyclic voltammogram shows a clear reduction wave that is assigned to AlSb compound formation. Deposits in this potential range are characterized by a homogeneous distribution of clusters with diameters of approximately 20 nm. Conductance spectra of these clusters exhibit the main features of the electronic structure of the bulk semiconductor AlSb, with a band gap of 2.0 +/- 0.2 eV. Electrodeposition experiments on both sides of the compound deposition potential show a strong doping effect that is manifest in the corresponding conductance spectra.

  15. ELECTRON MICROSCOPIC STUDIES OF RENAL DISEASE

    PubMed Central

    Latta, Harrison

    1960-01-01

    The nephrotic syndrome, glomerulonephritis, disseminated lupus erythematosus and the Fanconi syndrome show characteristic changes with electron microscopy. Experimental studies of animals were carried out to determine the significance of such changes by observing reactions that occur under carefully controlled conditions. A lesion with collagen deposition that was found in the centrolobular region of glomeruli sheds new light on the function of this region. This evidence must be considered in developing an understanding of how the production of urine is controlled. Fluid-filled compartments and various bodies associated with the ultrastructure of tubule cells can be produced under conditions which suggest that these structures play a role in tubular resorption. ImagesFigure 1, 2.Figure 3.Figure 4, 5.Figure 6, 7.Figure 8, 9.Figure 10.Figure 11, 12.Figure 13, 14.Figure 15, 16.Figure 17. PMID:13759386

  16. Electron Microscope Studies of the Human Epidermis

    PubMed Central

    Hibbs, Richard G.; Clark, Wallace H.

    1959-01-01

    The thin skin of the left upper quadrant of the human abdomen has been studied by electron microscopy. Tissue removed with a high speed rotary punch was fixed in osmium tetroxide or potassium permanganate. The latter fixative in our preparations is superior to osmium for the demonstration of epidermal cell membranes and certain other membranous structures of the epidermis. The cytoplasmic membranes of basal cells and cells of the stratum granulosum have been found to be relatively straight, while those of most spinous cells are sharply scalloped. The deep cells of the stratum spinosum in the rete ridge area show cell membranes and cytoplasmic structure intermediate between true basal cells and most cells of the stratum spinosum. The extracellular material of the desmosome has been found to consist of alternate dark and light laminae similar to those described by Odland (13) and Horstmann and Knoop (7). PMID:13673050

  17. Electron microscope study of Sarcocystis sp

    USGS Publications Warehouse

    Zeve, V.H.; Price, D.L.; Herman, C.M.

    1966-01-01

    Sarcocystis sp. obtained from wild populations of grackles, Quiscalus quiscula (Linn.), were examined to clarify the effect of the parasite on the host. Electron micrographs are presented to show areas of muscle destruction adjacent to the parasite which appear to be mechanically produced by the parasite. The microtubules within the villus-like projections of the cyst suggest that their possible function is absorptive and/or conductive with regard to the production of a toxin or the conveyance of nutritive material to the developing cells. The proposed function of submembranous filaments and their relation to the conoid is discussed. Similarities in the ultrastructure to Toxoplasma and other protozoa tend to negate the relegation of Sarcocystis to the fungi and further emphasize its protozoan nature.

  18. Development of scanning electron and x-ray microscope

    SciTech Connect

    Matsumura, Tomokazu Hirano, Tomohiko Suyama, Motohiro

    2016-01-28

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

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

    NASA Astrophysics Data System (ADS)

    Schmoeckel, Ferdinand; Fatikow, Sergej

    2000-06-01

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

  20. Dental Wear: A Scanning Electron Microscope Study

    PubMed Central

    Levrini, Luca; Di Benedetto, Giulia

    2014-01-01

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

  1. Dental wear: a scanning electron microscope study.

    PubMed

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

    2014-01-01

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

  2. A negative stain for electron microscopic tomography.

    PubMed

    Fera, Andrea; Farrington, Jane E; Zimmerberg, Joshua; Reese, Thomas S

    2012-04-01

    While negative staining can provide detailed, two-dimensional images of biological structures, the potential of combining tomography with negative staining to provide three-dimensional views has yet to be fully realized. Basic requirements of a negative stain for tomography are that the density and atomic number of the stain are optimal, and that the stain does not degrade or rearrange with the intensive electron dose (~10⁶ e/nm²) needed to collect a full set of tomographic images. A commercially available, tungsten-based stain appears to satisfy these prerequisites. Comparison of the surface structure of negatively stained influenza A virus with previous structural results served to evaluate this negative stain. The combination of many projections of the same structure yielded detailed images of single proteins on the viral surface. Corresponding surface renderings are a good fit to images of the viral surface derived from cryomicroscopy as well as to the shapes of crystallized surface proteins. Negative stain tomography with the appropriate stain yields detailed images of individual molecules in their normal setting on the surface of the influenza A virus.

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

    PubMed

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

    1998-01-01

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

  4. Resolution of the Electron Microscope at the Atomic Scale

    SciTech Connect

    O'Keefe, Dr. Michael; Allard Jr, Lawrence Frederick; Blom, Dr. Douglas

    2013-01-01

    The importance of atomic-resolution electron microscopy as a tool for structure analysis lies in its ability to produce images in which each peak corresponds to the position of an atom (or atomic column) within the specimen. Being able to distinguish between atoms (or columns) that appear close together when projected in the chosen viewing direction depends on the resolution of the microscope. Knowledge of the resolution of any particular electron microscope is crucial to judge if its resolution is appropriate for the specimen. In addition, resolution quality will determine the precision of measured atom positions.

  5. 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

  6. In situ nanoindentation in a transmission electron microscope

    SciTech Connect

    Minor, Andrew M.

    2002-01-01

    This dissertation presents the development of the novel mechanical testing technique of in situ nanoindentation in a transmission electron microscope (TEM). This technique makes it possible to simultaneously observe and quantify the mechanical behavior of nano-scale volumes of solids.

  7. Scanning electron microscope facility for examination of radioactive materials

    SciTech Connect

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

    1985-02-01

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

  8. [A view of tropical biology through the electron microscope].

    PubMed

    Hernández-Chavarría, Francisco

    2002-01-01

    The first electron microscope in Costa Rica was a donation from the government of Japan through its International Cooperation Agency (JICA) in 1974. This donation made possible the consolidation of what was to become the University of Costa Rica's Electron Microscope Unit (UME). Within three years the first scientific papers were published, dealing with ultrastructural aspects of "Corn's rayado fino virus" and rotavirus, viral agent of human diarrhea. Subsequent papers out of the UME were published for the most part in the Journal of Tropical Biology, totaling at least 50 in that journal alone by the year 2000. With the recent acquisition of Energy Dispersive Spectrometer to coupled in transmission electron microscope and scanning electron microscope to X ray analysis, the data acquisition of the UME has been greatly enhanced, making possible to analyze both structure and elemental chemical composition in a specimen. Other applications of this new technology include studies of environmental pollution with heavy metals, such as comparative analysis of residues on leaves from urban areas and those on leaves from primary forest.

  9. Achondrogenesis type I: light and electron-microscopic studies.

    PubMed

    Molz, G; Spycher, M A

    1980-06-01

    The light- and electron-microscopic structure of articular and costal cartilage in a case of achondrogenesis type I has been described. The most characteristic ultrastructural change in the chondrocytes was conspicuous dilatation of the rough endoplasmatic reticulum (RER) which contained amorphous electronopaque material. This change in the RER was accompanied by marked hypertrophy of the Golgi apparatus; the matrix was basically unchanged.

  10. High cycle fatigue in the transmission electron microscope

    SciTech Connect

    Bufford, Daniel C.; Stauffer, Douglas; Mook, William M.; Syed Asif, S. A.; Boyce, Brad L.; Hattar, Khalid

    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 applied at frequencies from one to several hundred hertz, enabling accumulations of 106 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.

  11. 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 106 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

  12. High Cycle Fatigue in the Transmission Electron Microscope.

    PubMed

    Bufford, Daniel C; Stauffer, Douglas; Mook, William M; Syed Asif, S A; Boyce, Brad L; Hattar, Khalid

    2016-08-10

    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 study, 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 applied 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. 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.

  13. High cycle fatigue in the transmission electron microscope

    SciTech Connect

    Bufford, Daniel C.; Stauffer, Douglas; Mook, William M.; Syed Asif, S. A.; Boyce, Brad L.; Hattar, Khalid

    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 applied at frequencies from one to several hundred hertz, enabling accumulations of 106 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.

  14. Examples of electrostatic electron optics: the Farrand and Elektros microscopes and electron mirrors.

    PubMed

    Hawkes, P W

    2012-08-01

    The role of Gertrude Rempfer in the design of the Farrand and Elektros microscopes is evoked. The study of electron mirror optics, aberration correction using mirrors and the development of microscopes employing electron mirrors are recapitulated, accompanied by a full bibliography, of earlier publications in particular.

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

    SciTech Connect

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

    2012-06-15

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

  16. 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.

  17. 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.

  18. Intrinsic Instability of Aberration-Corrected Electron Microscopes

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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.

  19. Secondary electron imaging of monolayer materials inside a transmission electron microscope

    SciTech Connect

    Cretu, Ovidiu 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.

  20. 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.

  1. Transmission electron microscope characterisation of molar-incisor-hypomineralisation.

    PubMed

    Xie, Zonghan; Kilpatrick, Nicky M; Swain, Michael V; Munroe, Paul R; Hoffman, Mark

    2008-10-01

    Molar-incisor-hypomineralisation (MIH), one of the major developmental defects in dental enamel, is presenting challenge to clinicians due, in part, to the limited understanding of microstructural changes in affected teeth. Difficulties in the preparation of site-specific transmission electron microscope (TEM) specimens are partly responsible for this deficit. In this study, a dual-beam field emission scanning electron microscope (FESEM)/focused ion beam (FIB) milling instrument was used to prepare electron transparent specimens of sound and hypomineralised enamel. Microstructural analysis revealed that the hypomineralised areas in enamel were associated with marked changes in microstructure; loosely packed apatite crystals within prisms and wider sheath regions were identified. Microstructural changes appear to occur during enamel maturation and may be responsible for the dramatic reduction in mechanical properties of the affected regions. An enhanced knowledge of the degradation of structural integrity in hypomineralised enamel could shed light on more appropriate management strategies for these developmental defects.

  2. Foucault imaging by using non-dedicated transmission electron microscope

    SciTech Connect

    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.

  3. Foucault imaging by using non-dedicated transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Taniguchi, Yoshifumi; Matsumoto, Hiroaki; Harada, Ken

    2012-08-01

    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.

  4. Purchase of a Transmission Electron Microscope for Xavier University of Louisiana

    DTIC Science & Technology

    2015-05-15

    SECURITY CLASSIFICATION OF: We solicited and received three price quotations for a research-grade transmission electron microscope : FEI, Inc... Electron Microscope (TEM). Delivery and installation were completed in December, 2014. The new TEM joins and complements an existing microscopic ...imaging facility on the second floor of the Pharmacy Addition at Xavier University that already includes two scanning electron microscopes . The new TEM

  5. Interaction-Free Quantum Electron Microscope in Free-Space

    NASA Astrophysics Data System (ADS)

    Yang, Yujia; Kim, Chung-Soo; Hobbs, Richard; Manfrinato, Vitor; Celiker, Orhan; Kruit, Pieter; Berggren, Karl

    2015-03-01

    We propose the design and theoretical analysis of a quantum electron microscope (QEM), which utilizes interaction-free quantum measurement with electrons for nanoscale imaging. The QEM can be used to image electron-irradiation-sensitive materials, such as biological samples, with a high resolution and low radiation damage. Our QEM scheme is an electron interferometer with a storage resonator. The incoming electron beam is asymmetrically split into a strong reference beam and a weak sample beam, both of which are stored in the resonator. Only the weak sample beam transmits through the sample for multiple times. We propose to build the QEM with free-space electron optics. We develop a scattering matrix method to theoretically analyze the contrast mechanism, radiation damage, and measurement accuracy. We propose an electron-mirror-based storage resonator and we have performed electron optics simulation of electron trajectories within the resonator. We also report experimental implementation and characterization of the electron beam-splitter to be used in the QEM. Thin crystals fabricated with focused ion beam and nano-gratings fabricated with electron-beam lithography are two candidate beam-splitters, both of which are characterized by electron diffraction. This work is funded by Gordon and Betty Moore Foundation.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. 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.

  8. 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.

  9. Sub-10 nm device fabrication in a transmission electron microscope.

    PubMed

    Fischbein, Michael D; Drndić, Marija

    2007-05-01

    We show that a high-resolution transmission electron microscope can be used to fabricate metal nanostructures and devices on insulating membranes by nanosculpting metal films. Fabricated devices include nanogaps, nanodiscs, nanorings, nanochannels, and nanowires with tailored curvatures and multi-terminal nanogap devices with nanoislands or nanoholes between the terminals. The high resolution, geometrical flexibility, and yield make this fabrication method attractive for many applications including nanoelectronics and nanofluidics.

  10. 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).

  11. Ion charge neutralization effects in scanning electron microscopes.

    PubMed

    Crawford, C K

    1980-01-01

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

  12. Circular dichroism in the electron microscope: Progress and applications (invited)

    SciTech Connect

    Schattschneider, P.; Loeffler, S.; Ennen, I.; Stoeger-Pollach, M.; Verbeeck, J.

    2010-05-15

    According to theory, x-ray magnetic circular dichroism in a synchrotron is equivalent to energy loss magnetic chiral dichroism (EMCD) in a transmission electron microscope (TEM). After a synopsis of the development of EMCD, the theoretical background is reviewed and recent results are presented, focusing on the study of magnetic nanoparticles for ferrofluids and Heusler alloys for spintronic devices. Simulated maps of the dichroic strength as a function of atom position in the crystal allow evaluating the influence of specimen thickness and sample tilt on the experimental EMCD signal. Finally, the possibility of direct observation of chiral electronic transitions with atomic resolution in a TEM is discussed.

  13. 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.

  14. 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.

  15. A fast iterative technique for restoring scanning electron microscope images

    NASA Astrophysics Data System (ADS)

    Nakahira, Kenji; Miyamoto, Atsushi; Honda, Toshifumi

    2014-12-01

    This paper proposes a fast new technique for restoring scanning electron microscope images to improve their sharpness. The images with our approach are sharpened by deconvolution with the point spread function modeled as the intensity distribution of the electron beam at the specimen's surface. We propose an iterative technique that employs a modified cost function based on the Richardson-Lucy method to achieve faster processing. The empirical results indicate significant improvements in image quality. The proposed approach speeds up deconvolution by about 10-50 times faster than that with the conventional Richardson-Lucy method.

  16. Automation of electron diffraction analysis in an analytical electron microscope

    SciTech Connect

    Carr, M.J.

    1981-07-01

    This paper outlines the concept of gathering and analyzing electron diffraction patterns in an AEM by using a computer to digitally control the operation of a set of post-projector lens scan coils. By digitally controlling the deflection of a static selected area diffraction pattern either to a fixed reference point or in a reduced raster over the apertured STEM detector, a set of electronic signals may be generated which contain information of the form I = f(x,y). Not only can this signal be rapidly processed to provide real-time analyses of diffracted distances and angles of spots in the pattern, but also the operator maintains control over the scanning coils (via joystick) allowing only selected spots to be gathered and analyzed, thus facilitating the analysis of imperfect of multiple patterns. A description of the hardware and software is given, as well as preliminary results and current limitations.

  17. Topics in recent studies with high-voltage electron microscopes.

    PubMed

    Mori, Hirotaro

    2011-01-01

    In this article, topics in recent studies with high-voltage electron microscopes (HVEMs) are reviewed. High-voltage electron microscopy possesses a number of advantages that cannot be afforded by conventional electron microscopy, thus providing a unique microscopy technique in both materials science and biological science. One of these advantages is the capability of continuously observing phenomena using a variety of electron microscopy techniques simultaneously with the introduction of the displacement of atoms from lattice points. This has enabled in-depth studies on such fundamental subjects as the crystalline-to-amorphous-to-crystalline transition, the motion properties of point defects and the one-dimensional diffusion of dislocation loops. Electron tomography studies using HVEMs take advantage of the large observable thickness of a specimen. In addition, by combining different advantages, a number of advanced applications in materials science have been carried out, including analyses of the atomic structure of a reduction-induced reconstructed surface and the atomic mechanism behind the self-catalytic vapor-liquid-solid growth of an oxide nanowire. As long as excellent and invaluable studies that cannot be carried out without HVEMs appear in succession, it is necessary to make the utmost efforts to improve these microscopes.

  18. Pulsed Power for a Dynamic Transmission Electron Microscope

    SciTech Connect

    dehope, w j; browning, n; campbell, g; cook, e; king, w; lagrange, t; reed, b; stuart, b; Shuttlesworth, R; Pyke, B

    2009-06-25

    Lawrence Livermore National Laboratory (LLNL) has converted a commercial 200kV transmission electron microscope (TEM) into an ultrafast, nanoscale diagnostic tool for material science studies. The resulting Dynamic Transmission Electron Microscope (DTEM) has provided a unique tool for the study of material phase transitions, reaction front analyses, and other studies in the fields of chemistry, materials science, and biology. The TEM's thermionic electron emission source was replaced with a fast photocathode and a laser beam path was provided for ultraviolet surface illumination. The resulting photoelectron beam gives downstream images of 2 and 20 ns exposure times at 100 and 10 nm spatial resolution. A separate laser, used as a pump pulse, is used to heat, ignite, or shock samples while the photocathode electron pulses, carefully time-synchronized with the pump, function as probe in fast transient studies. The device functions in both imaging and diffraction modes. A laser upgrade is underway to make arbitrary cathode pulse trains of variable pulse width of 10-1000 ns. Along with a fast e-beam deflection scheme, a 'movie mode' capability will be added to this unique diagnostic tool. This talk will review conventional electron microscopy and its limitations, discuss the development and capabilities of DTEM, in particularly addressing the prime and pulsed power considerations in the design and fabrication of the DTEM, and conclude with the presentation of a deflector and solid-state pulser design for Movie-Mode DTEM.

  19. Image resolution and sensitivity in an environmental transmission electron microscope.

    PubMed

    Jinschek, J R; Helveg, S

    2012-11-01

    An environmental transmission electron microscope provides unique means for the atomic-scale exploration of nanomaterials during the exposure to a reactive gas environment. Here we examine conditions to obtain such in situ observations in the high-resolution transmission electron microscopy (HRTEM) mode with an image resolution of 0.10nm. This HRTEM image resolution threshold is mapped out under different gas conditions, including gas types and pressures, and under different electron optical settings, including electron beam energies, doses and dose-rates. The 0.10nm resolution is retainable for H(2) at 1-10mbar. Even for N(2), the 0.10nm resolution threshold is reached up to at least 10mbar. The optimal imaging conditions are determined by the electron beam energy and the dose-rate as well as an image signal-to-noise (S/N) ratio that is consistent with Rose's criterion of S/N≥5. A discussion on the electron-gas interactions responsible for gas-induced resolution deterioration is given based on interplay with complementary electron diffraction (ED), scanning transmission electron microscopy (STEM) as well as electron energy loss spectroscopy (EELS) data.

  20. 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.

  1. Photocathode Optimization for a Dynamic Transmission Electron Microscope: Final Report

    SciTech Connect

    Ellis, P; Flom, Z; Heinselman, K; Nguyen, T; Tung, S; Haskell, R; Reed, B W; LaGrange, T

    2011-08-04

    The Dynamic Transmission Electron Microscope (DTEM) team at Harvey Mudd College has been sponsored by LLNL to design and build a test setup for optimizing the performance of the DTEM's electron source. Unlike a traditional TEM, the DTEM achieves much faster exposure times by using photoemission from a photocathode to produce electrons for imaging. The DTEM team's work is motivated by the need to improve the coherence and current density of the electron cloud produced by the electron gun in order to increase the image resolution and contrast achievable by DTEM. The photoemission test setup is nearly complete and the team will soon complete baseline tests of electron gun performance. The photoemission laser and high voltage power supply have been repaired; the optics path for relaying the laser to the photocathode has been finalized, assembled, and aligned; the internal setup of the vacuum chamber has been finalized and mostly implemented; and system control, synchronization, and data acquisition has been implemented in LabVIEW. Immediate future work includes determining a consistent alignment procedure to place the laser waist on the photocathode, and taking baseline performance measurements of the tantalum photocathode. Future research will examine the performance of the electron gun as a function of the photoemission laser profile, the photocathode material, and the geometry and voltages of the accelerating and focusing components in the electron gun. This report presents the team's progress and outlines the work that remains.

  2. Elastofibroma. A correlated light and electron microscopic study.

    PubMed

    Kindblom, L G; Spicer, S S

    1982-01-01

    Four cases of elastofibroma located in the subscapular region of 3 men aged 66, 74, and 83 years, and a woman 70 years old are reported. A correlated light and electron microscopic study including ultrastructural examination of Verhoeff's iron-hematoxylin (VIH)-stained sections was performed. Light microscopically, the elastofibromas were characterized by connective tissue built up by collagen fibers and sclerotic masses mingled with numerous fibers and globules of elastin material. In one micron thick Epon sections these elastin fibers often revealed a central axis surrounded by a mantle composed of periodic segments giving them a necklace-like appearance. The ultrastructural findings of these elastin structures, stained with VIH, and the appearance of the stroma cells and their relation to the elastin indicate that elastofibroma is a non-neoplastic reactive lesion in which elastin material is synthesized by the stromal cells and predominantly laid down around preexisting elastic fibers.

  3. 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.

  4. Which image parameter(s) for the automation of the electron microscope?

    PubMed

    Bonnet, N; Zinzindohoue, P

    1989-03-01

    Experiments on automating the transmission electron microscope rely on the search for minimum variance. This image parameter gives satisfactory results for automatic focusing, astigmatism correction, and beam alignment. We investigate here the different image descriptors that might also be used; we conclude that texture parameters, which are directional, would be better candidates correcting astigmatism and beam tilt.

  5. In situ laser processing in a scanning electron microscope

    SciTech Connect

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

    2012-07-15

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

  6. In situ laser processing in a scanning electron microscope

    SciTech Connect

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

    2012-01-01

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

  7. Observation of Materials Processes in Liquids in the Electron Microscope

    SciTech Connect

    Wang, Chong M.; Liao, Honggang; Ross, Frances M.

    2015-01-01

    Materials synthesis and the functioning of devices often indispensably involve liquid media. But direct visualization of dynamic process in liquids, especially with high spatial and temporal resolution, has been challenging. For solid materials, advances in aberration corrected electron microscopy have made observation of atomic level features a routine practice. Here we discuss the extent to which one can take advantage of the resolution of modern electron microscopes to image phenomenon occuring in liquids. We will describe the fundamentals of two different experimental approaches, closed and open liquid cells. We will illustrate the capabilities of each approach by considering processes in batteries and nucleation and growth of nanoparticles from solution. We conclude that liquid cell electron microscopy appears to be duly fulfilling its role for in situ studies of nanoscale processes in liquids, revealing physical and chemical processes otherwise difficult to observe.

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

    SciTech Connect

    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 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 no 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.

  9. 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

  10. Understanding oxide interfaces: From microscopic imaging to electronic phases

    NASA Astrophysics Data System (ADS)

    Ilani, Shahal

    2014-03-01

    In the last decade, the advent of complex oxide interfaces has unleashed a wealth of new possibilities to create materials with unexpected functionalities. A notable example is the two-dimensional electron system formed at the interface between LaAlO3 and SrTiO3 (LAO/STO), which exhibits ferromagnetism, superconductivity, and a wide range of unique magneto-transport properties. A key challenge is to find the microscopic mechanisms that underlie these emergent phenomena. While there is a growing understanding that these phenomena might reflect rich structures at the micro-scale, experimental progress toward microscopic imaging of this system has been so far rather limited due to the buried nature of its interface. In this talk I will discuss our experiments that study this system on microscopic and macroscopic scales. Using a newly-developed nanotube-based scanning electrometer we image on the nanoscale the electrostatics and mechanics of this buried interface. We reveal the dynamics of structural domains in STO, their role in generating the contested anomalous piezoelectricity of this substrate, and their direct effects on the physics of the interface electrons. Using macroscopic magneto-transport experiments we demonstrate that a universal Lifshitz transition between the population of d-orbitals with different symmetries underlies many of the transport phenomena observed to date. We further show that the interactions between the itinerant electrons and localized spins leads to an unusual, gate-tunable magnetic phase diagram. These measurements highlight the unique physical settings that can be realized within this new class of low dimensional systems.

  11. Integrated windows-based control system for an electron microscope

    NASA Astrophysics Data System (ADS)

    Ruan, Shengyang; Kapp, Oscar H.

    1994-12-01

    A Windows application has been developed for management and operation of beam instruments such as electron or ion microscopes. It provides a facility that allows an operator to manage a complicated instrument with minimal effort, primarily under mouse control. The hardware control components used on similar instruments (e.g., the scanning transmission electron microscopes in our lab), such as toggles, buttons, and potentiometers for adjustments on various scales, are all replaced by the controls of the Windows application and are addressable on a single screen. The new controls in this program (via adjustable software settings) offer speed of response and smooth operation providing tailored control of various instrument parameters. Along with the controls offering single parameter adjustment, a two-dimensional control was developed that allows two parameters to be coupled and addressed simultaneously. This capability provides convenience for such tasks as ``finding the beam'' and directing it to a location of interest on the specimen. Using an icon-based display, this Windows application provides better integrated and more robust information for monitoring instrument status than the indicators and meters of the traditional instrument controls. As a Windows application, this program is naturally able to share the resources of the Windows system and is thus able to link to many other applications such as our image acquisition and processing programs. Computer control provides automatic protection and instant diagnostics for the experimental instrument. This Windows application is fully functional and is in daily use to control a new type of electron microscope developed in our lab.

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

    NASA Technical Reports Server (NTRS)

    Nicolas, D. P.

    1974-01-01

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

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

    SciTech Connect

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

    2015-07-22

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

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

    NASA Technical Reports Server (NTRS)

    Nicolas, D. P.

    1974-01-01

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

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

    PubMed

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

    2016-01-01

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

  16. Purification and electron microscopic visualization of functional human spliceosomes

    PubMed Central

    Zhou, Zhaolan; Sim, Jeonggu; Griffith, Jack; Reed, Robin

    2002-01-01

    Pre-mRNA splicing takes place in a large and highly dynamic complex known as the spliceosome. Here we report the optimization of a maltose-binding protein (MBP) affinity-purification method to isolate functional spliceosomes for electron microscopic analysis. Visualization of the spliceosome preparations revealed distinct 40–60 nm particles. Immunogold-conjugated antibodies to spliceosome components specifically label these particles, which are eliminated by treatment with either RNase or protease. Moreover, spliceosomes assembled on two different pre-mRNAs are indistinguishable. This first visualization of purified functional spliceosomes assembled in vitro reveals striking structural features, including one or more central cavities and multiple elongate lobes. PMID:12215496

  17. Single cylinder in situ scanning electron microscope fatigue system

    SciTech Connect

    Smiltneek, Larry; Shinde, Sachin R.; Hoeppner, David W.

    2006-01-15

    This article introduces a single cylinder fatigue machine adaptable to a scanning electron microscope chamber. The machine includes a node control mechanism to create a still observation node at any location on the specimen as fatigue cycling occurs, thereby allowing a point of interest to remain within view. The exceptional stability of this machine enables improved in situ study of the fatigue cracking phenomenon. For example, an in situ machine enhances the researcher's ability to record material structural changes that precede crack nucleation and allows observation of the influences of microstructure (grain structure) on the early stages of crack propagation.

  18. 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.

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

    SciTech Connect

    Bormann, Reiner; Strauch, Stefanie; Schäfer, Sascha Ropers, Claus

    2015-11-07

    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.

  20. Electron-beam-induced ferroelectric domain behavior in the transmission electron microscope: Toward deterministic domain patterning

    NASA Astrophysics Data System (ADS)

    Hart, James L.; Liu, Shi; Lang, Andrew C.; Hubert, Alexander; Zukauskas, Andrius; Canalias, Carlota; Beanland, Richard; Rappe, Andrew M.; Arredondo, Miryam; Taheri, Mitra L.

    2016-11-01

    We report on transmission electron microscope beam-induced ferroelectric domain nucleation and motion. While previous observations of this phenomenon have been reported, a consistent theory explaining induced domain response is lacking, and little control over domain behavior has been demonstrated. We identify positive sample charging, a result of Auger and secondary electron emission, as the underlying mechanism driving domain behavior. By converging the electron beam to a focused probe, we demonstrate controlled nucleation of nanoscale domains. Molecular dynamics simulations performed are consistent with experimental results, confirming positive sample charging and reproducing the result of controlled domain nucleation. Furthermore, we discuss the effects of sample geometry and electron irradiation conditions on induced domain response. These findings elucidate past reports of electron beam-induced domain behavior in the transmission electron microscope and provide a path towards more predictive, deterministic domain patterning through electron irradiation.

  1. Phase Identification in a Scanning Electron Microscope Using Backscattered Electron Kikuchi Patterns

    PubMed Central

    Goehner, R. P.; Michael, J. R.

    1996-01-01

    Backscattered electron Kikuchi patterns (BEKP) suitable for crystallographic phase analysis can be collected in the scanning electron microscope (SEM) with a newly developed charge coupled device (CCD) based detector. Crystallographic phase identification using BEKP in the SEM is unique in that it permits high magnification images and BEKPs to be collected from a bulk specimen. The combination of scanning electron microscope (SEM) imaging, BEKP, and energy dispersive x-ray spectrometry holds the promise of a powerful new tool for materials science. PMID:27805167

  2. 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.

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

    SciTech Connect

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

    2005-08-15

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

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

    SciTech Connect

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

    2015-06-23

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

  5. Electron microscopic localization of cytoplasmic myosin with ferritin- labeled antibodies

    PubMed Central

    1981-01-01

    We localized myosin in vertebrate nonmuscle cells by electron microscopy using purified antibodies coupled with ferritin. Native and formaldehyde-fixed filaments of purified platelet myosin filaments each consisting of approximately 30 myosin molecules bound an equivalent number of ferritin-antimyosin conjugates. In preparations of crude platelet actomyosin, the ferritin-antimyosin bound exclusively to similar short, 10-15 nm wide filaments. In both cases, binding of the ferritin-antimyosin to the myosin filaments was blocked by preincubation with unlabeled antimyosin. With indirect fluorescent antibody staining at the light microscope level, we found that the ferritin-antimyosin and unlabeled antimyosin stained HeLa cells identically, with the antibodies concentrated in 0.5-microns spots along stress fibers. By electron microscopy, we found that the concentration of ferritin-antimyosin in the dense regions of stress fibers was five to six times that in the intervening less dense regions, 20 times that in the cytoplasmic matrix, and 100 times that in the nucleus. These concentration differences may account for the light microscope antibody staining pattern of spread interphase cells. Some, but certainly not all, of the ferritin-antimyosin was associated with 10-15-nm filaments. In mouse intestinal epithelial cells, ferritin- antimyosin was located almost exclusively in the terminal web. In isolated brush borders exposed to 5 mM MgCl2, ferritin-antimyosin was also concentrated in the terminal web associated with 10-15-nm filaments. PMID:7193682

  6. Transmission electron microscope calibration methods for critical dimension standards

    NASA Astrophysics Data System (ADS)

    Orji, Ndubuisi G.; Dixson, Ronald G.; Garcia-Gutierrez, Domingo I.; Bunday, Benjamin D.; Bishop, Michael; Cresswell, Michael W.; Allen, Richard A.; Allgair, John A.

    2016-10-01

    One of the key challenges in critical dimension (CD) metrology is finding suitable dimensional calibration standards. The transmission electron microscope (TEM), which produces lattice-resolved images having scale traceability to the SI (International System of Units) definition of length through an atomic lattice constant, has gained wide usage in different areas of CD calibration. One such area is critical dimension atomic force microscope (CD-AFM) tip width calibration. To properly calibrate CD-AFM tip widths, errors in the calibration process must be quantified. Although the use of TEM for CD-AFM tip width calibration has been around for about a decade, there is still confusion on what should be considered in the uncertainty analysis. We characterized CD-AFM tip-width samples using high-resolution TEM and high angle annular dark field scanning TEM and two CD-AFMs that are implemented as reference measurement systems. The results are used to outline how to develop a rigorous uncertainty estimate for TEM/CD-AFM calibration, and to compare how information from the two electron microscopy modes are applied to practical CD-AFM measurements. The results also represent a separate validation of previous TEM/CD-AFM calibration. Excellent agreement was observed.

  7. Light- and electron-microscopic histochemistry of Fabry's disease.

    PubMed Central

    Faraggiana, T.; Churg, J.; Grishman, E.; Strauss, L.; Prado, A.; Bishop, D. F.; Schuchman, E.; Desnick, R. J.

    1981-01-01

    A histochemical study was performed on light- and electron-microscopic level in a case of Fabry's disease. The patient underwent kidney transplantation for renal failure and died of heart failure 6 months later. Patient's tissues were studied at the light- and electron-microscopic levels with various embedding and staining techniques for lipids and carbohydrates. Two peroxidase-labeled lectins (from Ricinus communis and from Bandeiraea simplicifolia) known to have affinity for alpha- and beta-D-galactose, were strongly reactive with the storage material on frozen sections. The ultrahistochemical and extraction tests showed that the typical granules had a variable reactivity and morphologic characteristics in different cells, probably reflecting different composition. A small number of typical deposits were also observed in the transplanted kidney. This is the first reported case of recurrence of the storage disease in the allograft. Of interest was also the fact that the patient's blood inhibited normal alpha-galactosidase activity, suggesting a possible inhibitor-related mechanism in the pathogenesis of the recurrence. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 PMID:6786101

  8. Stereo-microvision. Development of an opto-electronic operating microscope.

    PubMed

    Reinhardt, H F; Horstmann, G A; Spink, R; Amrein, E I; Forrer, P

    1993-06-01

    A novel opto-electronic operating microscope has been designed and clinically tested. It consists of a small camera microscope, a central electronic unit, and a stereoscopic video monitor. Advanced miniaturization permitted ergonomics superior to those of conventional optomechanical microscopes. Electronic imaging facilitates coupling to an ultrasound navigation system which enables the neurosurgeon to verify the location of the focus in real time, correlated with CT and MRI pictures. A fully computerized, digital operating microscope will now be developed based on this prototype.

  9. Microscopic theory of the residual surface resistivity of Rashba electrons

    NASA Astrophysics Data System (ADS)

    Bouaziz, Juba; Lounis, Samir; Blügel, Stefan; Ishida, Hiroshi

    2016-07-01

    A microscopic expression of the residual electrical resistivity tensor is derived in linear response theory for Rashba electrons scattering at a magnetic impurity with cylindrical or noncylindrical potential. The behavior of the longitudinal and transversal residual resistivity is obtained analytically and computed for an Fe impurity at the Au(111) surface. We studied the evolution of the resistivity tensor elements as a function of the Rashba spin-orbit strength and the magnetization direction of the impurity. We found that the absolute values of longitudinal resistivity reduce with increasing spin-orbit strength of the substrate and that the scattering of the conduction electrons at magnetic impurities with magnetic moments pointing in directions not perpendicular to the surface plane produce a planar Hall effect and an anisotropic magnetoresistance even if the impurity carries no spin-orbit interaction. Functional forms are provided describing the anisotropy of the planar Hall effect and the anisotropic magnetoresistance with respect to the direction of the impurity moment. In the limit of no spin-orbit interaction and a nonmagnetic impurity of cylindrical symmetry, the expression of the residual resistivity of a two-dimensional electron gas has the same simplicity and form as for the three-dimensional electron gas [J. Friedel, J. Nuovo. Cim. 7, 287 (1958), 10.1007/BF02751483] and can also be expressed in terms of scattering phase shifts.

  10. 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.

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

    PubMed

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

    2011-06-01

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

  12. Femtosecond electron spectroscopy in an electron microscope with high brightness beams

    NASA Astrophysics Data System (ADS)

    Zhou, Faran; Williams, Joseph; Ruan, Chong-Yu

    2017-09-01

    A concept of performing femtosecond electron spectroscopy in an electron microscope with adaptive optics to handle space-charge-dominated beams is presented. Improved temporal-spectral resolutions are obtained through a combination of time and energy compression optics to disentangle the spectral information buried in temporally compressed pulses. A combined ∼1 eV-sub-ps performance with 105 electrons in single pulses, and femtosecond core-level spectroscopy at single-shots with higher doses are demonstrated. This strategy provides several orders of magnitude improvement in sensitivity compared to the state-of-the-art ultrafast electron microscopes, representing a flexible solution for studying electronic and chemical dynamics in complex systems overcoming the collective space-charge limitations.

  13. Transmission electron microscope sample holder with optical features

    DOEpatents

    Milas, Mirko [Port Jefferson, NY; Zhu, Yimei [Stony Brook, NY; Rameau, Jonathan David [Coram, NY

    2012-03-27

    A sample holder for holding a sample to be observed for research purposes, particularly in a transmission electron microscope (TEM), generally includes an external alignment part for directing a light beam in a predetermined beam direction, a sample holder body in optical communication with the external alignment part and a sample support member disposed at a distal end of the sample holder body opposite the external alignment part for holding a sample to be analyzed. The sample holder body defines an internal conduit for the light beam and the sample support member includes a light beam positioner for directing the light beam between the sample holder body and the sample held by the sample support member.

  14. A Transmission Electron Microscope Study of Experimentally Shocked Pregraphitic Carbon

    NASA Technical Reports Server (NTRS)

    Rietmeijer, Frans J. M.

    1995-01-01

    A transmission electron microscope study of experimental shock metamorphism in natural pre-graphitic carbon simulates the response of the most common natural carbons to increased shock pressure. The d-spacings of this carbon are insensitive to the shock pressure and have no apparent diagnostic value, but progressive comminution occurs in response to increased shock pressure up to 59.6 GPa. The function, P = 869.1 x (size(sub minimum )(exp -0.83), describes the relationship between the minimum root-mean-square subgrain size (nm) and shock pressure (GPa). While a subgrain texture of natural pregraphitic carbons carries little information when pre-shock textures are unknown, this texture may go unnoticed as a shock metamorphic feature.

  15. Wide-range tunable magnetic lens for tabletop electron microscope.

    PubMed

    Chang, Wei-Yu; Chen, Fu-Rong

    2016-12-01

    A tabletop scanning electron microscope (SEM) utilizes permanent magnets as condenser lenses to minimize its size, but this sacrifices the tunability of condenser lenses such that a tabletop system can only be operated with a fixed accelerating voltage. In contrast, the traditional condenser lens utilizes an electromagnetic coil to adjust the optical properties, but the size of the electromagnetic lens is inevitably larger. Here, we propose a tunable condenser lens for a tabletop SEM that uses a combination of permanent magnets and electromagnetic coils. The overall dimensions of the newly designed lens are the same as the original permanent magnet lens, but the new lens allows the tabletop SEM to be operated at different accelerating voltages between 1kV and 15kV. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Pigmentosis tubae, a new entity: light and electron microscopic study

    SciTech Connect

    Herrera, G.A.; Reimann, B.E.; Greenberg, H.L.; Miles, P.A.

    1983-03-01

    The authors noted an unusual finding in the fallopian tubes of a 31-year-old woman who had received external and internal whole pelvis radiotherapy for squamous cell carcinoma of the cervix. Aggregates of macrophages containing pigment, identified in a subepithelial location, were reminiscent of melanosis coli, which is caused by abuse of anthracene-containing laxatives. Electron microscopic examination of the pigment revealed cytoplasmic material with the appearance of lipofuscin, identical to the pigment described in cases of colonic melanosis. After a careful study of possible etiologic agents, it was concluded that the pigment most likely resulted from cellular damage caused by radiotherapy. The authors are not aware of any other reported case of this entity, which will be called pigmentosis tubae.

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

    PubMed

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

    2012-06-01

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

  18. Edge-on ion irradiation of electron microscope specimens

    SciTech Connect

    Otero, M.P. |; Allen, C.W.

    1992-07-01

    A special technique is described for in situ transmission electron microscope (TEM) experiments involving simultaneous ion irradiation, in which the resultant phenomena are observed as in a cross-section TEM specimen. That is, instead of ion-irradiating the film or foil specimen normal to the major surfaces and observing in plan view (i.e., in the same direction), the specimen is irradiated edge-on (i.e., parallel to the major surfaces) and is observed normal to the depth direction with respect to the irradiation. The results of amorphization of Si, irradiated in this orientation by 1 or 1.5 MeV Kr, are presented and briefly compared with the usual plan view observations. The limitations of the technique are discussed and several experiments which might profitably employ this technique are suggested.

  19. Edge-on ion irradiation of electron microscope specimens

    SciTech Connect

    Otero, M.P. Fundacao de Tecnologia Industrial , Lorena, SP ); Allen, C.W. )

    1992-01-01

    A special technique is described for in situ transmission electron microscope (TEM) experiments involving simultaneous ion irradiation, in which the resultant phenomena are observed as in a cross-section TEM specimen. That is, instead of ion-irradiating the film or foil specimen normal to the major surfaces and observing in plan view (i.e., in the same direction), the specimen is irradiated edge-on (i.e., parallel to the major surfaces) and is observed normal to the depth direction with respect to the irradiation. The results of amorphization of Si, irradiated in this orientation by 1 or 1.5 MeV Kr, are presented and briefly compared with the usual plan view observations. The limitations of the technique are discussed and several experiments which might profitably employ this technique are suggested.

  20. Ultrafast imaging of plasmons in a transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Lummen, Tom T. A.; Berruto, Gabriele; Toma, Andrea; Lamb, Raymond J.; McGrouther, Damien; Carbone, Fabrizio

    2016-03-01

    Miniaturized plasmonic and photonic integrated circuits are generally considered as the core of future generations of optoelectronic devices, due to their potential to bridge the size-compatibility gap between photonics and electronics. However, as the nanoscale is approached in increasingly small plasmonic and photonic systems, experimentally observing their behavior involves ever more stringent requirements in terms of both temporal and spatial resolution. This talk focuses on the use of time-resolved Photon-Induced Near-Field Electron Microscopy (PINEM) to study the excitation, propagation, (self-)interference and dynamics of surface plasmon polaritons (SPPs) in various plasmonic nanostructures with both nanometer and ultrafast resolution in a transmission electron microscope. Using this field-ofview technique, we directly show how photo-excited plasmonic interference patterns are controlled through the combination of excitation polarization and nanostructure geometry. Moreover, we capture the propagation of the photoinduced self-interfering plasmonic wave, clearly demonstrating the effects of axial confinement in nanostructured plasmonic thin film stacks.

  1. Structural Fingerprinting of Nanocrystals in the Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Rouvimov, Sergei; Plachinda, Pavel; Moeck, Peter

    2010-03-01

    Three novel strategies for the structurally identification of nanocrystals in a transmission electron microscope are presented. Either a single high-resolution transmission electron microscopy image [1] or a single precession electron diffractogram (PED) [2] may be employed. PEDs from fine-grained crystal powders may also be utilized. Automation of the former two strategies is in progress and shall lead to statistically significant results on ensembles of nanocrystals. Open-access databases such as the Crystallography Open Database which provides more than 81,500 crystal structure data sets [3] or its mainly inorganic and educational subsets [4] may be utilized. [1] http://www.scientificjournals.org/journals 2007/j/of/dissertation.htm [2] P. Moeck and S. Rouvimov, in: {Drugs and the Pharmaceutical Sciences}, Vol. 191, 2009, 270-313 [3] http://cod.ibt.lt, http://www.crystallography.net, http://cod.ensicaen.fr, http://nanocrystallography.org, http://nanocrystallography.net, http://journals.iucr.org/j/issues/2009/04/00/kk5039/kk5039.pdf [4] http://nanocrystallography.research.pdx.edu/CIF-searchable

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

    SciTech Connect

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

    2015-06-24

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

  3. 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.

  4. Visualization of macromolecular complexes using cryo-electron microscopy with FEI Tecnai transmission electron microscopes

    PubMed Central

    Grassucci, Robert A; Taylor, Derek; Frank, Joachim

    2009-01-01

    This protocol details the steps used for visualizing the frozen-hydrated grids as prepared following the accompanying protocol entitled ‘Preparation of macromolecular complexes for visualization using cryo-electron microscopy.’ This protocol describes how to transfer the grid to the microscope using a standard cryo-transfer holder or, alternatively, using a cryo-cartridge loading system, and how to collect low-dose data using an FEI Tecnai transmission electron microscope. This protocol also summarizes and compares the various options that are available in data collection for three-dimensional (3D) single-particle reconstruction. These options include microscope settings, choice of detectors and data collection strategies both in situations where a 3D reference is available and in the absence of such a reference (random-conical and common lines). PMID:18274535

  5. Bacterial Biofilm Morphology on a Failing Implant with an Oxidized Surface: A Scanning Electron Microscope Study.

    PubMed

    Simion, Massimo; Kim, David M; Pieroni, Stefano; Nevins, Myron; Cassinelli, Clara

    2016-01-01

    This case report provided a unique opportunity to investigate the extent of microbiota infiltration on the oxidized implant surface that has been compromised by peri-implantitis. Scanning electron microscopic analysis confirmed the etiologic role of the bacteria on the loss of supporting structure and the difficulty in complete removal of bacterial infiltration on the implant surface. This case report emphasizes the need to perform definitive surface decontamination on failing dental implants prior to a regeneration procedure.

  6. 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.

  7. Macroanatomic, light and scanning electron microscopic studies of the pecten oculi in the stork (Ciconia ciconia).

    PubMed

    Onuk, Burcu; Tutuncu, Serife; Alan, Aydin; Kabak, Murat; Ince, Nazan Gezer

    2013-09-01

    This study was undertaken to investigate the pecten oculi of stork by using macroscopic, light and electron microscopic techniques. A total of 20 eyes that were obtained from 10 storks were used. The eyes were cleaned and isolated by dissection. After various procedures, four of the pecten oculi were examined by light microscope while the other four with an electron microscope. The remaining 12 eyes were assigned for macroscopic investigation. Pecten oculi of the stork were determined as accordion-like structures that originated from n. opticus, consisting of 15-17 plica and projecting up to 2/5 of the diameter of the bulbus oculi. Light microscopic examination revealed two types of blood vessels. Afferent-efferent vessels were larger in diamater (40-45 µm), fewer in numbers, and the capillary vessels were smaller in diamater (2-5 µm) and more in numbers. There were granules including amount of melanin pigment at the apical part of the pleats. These granules were fewer and scattered randomly on the basal part of the pleats. As a result, pecten oculi in the stork, which is a migrating bird, were determined to be similar to those of other diurnal birds.

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

    PubMed

    Khursheed, Anjam

    2005-07-01

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

  9. Scanning electron microscope automatic defect classification of process induced defects

    NASA Astrophysics Data System (ADS)

    Wolfe, Scott; McGarvey, Steve

    2017-03-01

    With the integration of high speed Scanning Electron Microscope (SEM) based Automated Defect Redetection (ADR) in both high volume semiconductor manufacturing and Research and Development (R and D), the need for reliable SEM Automated Defect Classification (ADC) has grown tremendously in the past few years. In many high volume manufacturing facilities and R and D operations, defect inspection is performed on EBeam (EB), Bright Field (BF) or Dark Field (DF) defect inspection equipment. A comma separated value (CSV) file is created by both the patterned and non-patterned defect inspection tools. The defect inspection result file contains a list of the inspection anomalies detected during the inspection tools' examination of each structure, or the examination of an entire wafers surface for non-patterned applications. This file is imported into the Defect Review Scanning Electron Microscope (DRSEM). Following the defect inspection result file import, the DRSEM automatically moves the wafer to each defect coordinate and performs ADR. During ADR the DRSEM operates in a reference mode, capturing a SEM image at the exact position of the anomalies coordinates and capturing a SEM image of a reference location in the center of the wafer. A Defect reference image is created based on the Reference image minus the Defect image. The exact coordinates of the defect is calculated based on the calculated defect position and the anomalies stage coordinate calculated when the high magnification SEM defect image is captured. The captured SEM image is processed through either DRSEM ADC binning, exporting to a Yield Analysis System (YAS), or a combination of both. Process Engineers, Yield Analysis Engineers or Failure Analysis Engineers will manually review the captured images to insure that either the YAS defect binning is accurately classifying the defects or that the DRSEM defect binning is accurately classifying the defects. This paper is an exploration of the feasibility of the

  10. 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 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 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.

  11. ELECTRON ABSORBED FRACTIONS IN AN IMAGE-BASED MICROSCOPIC SKELETAL DOSIMETRY MODEL OF CHINESE ADULT MALE.

    PubMed

    Gao, Shenshen; Ren, Li; Qiu, Rui; Wu, Zhen; Li, Chunyan; Li, Junli

    2017-01-10

    Based on the Chinese reference adult male voxel model, a set of microscopic skeletal models of Chinese adult male is constructed through the processes of computed tomography (CT) imaging, bone coring, micro-CT imaging, image segmentation, merging into macroscopic bone model and implementation in Geant4. At the step of image segmentation, a new bone endosteum (BE) segmentation method is realized by sampling. The set of model contains 32 spongiosa samples with voxel size of 19 μm cubes. The microscopic spongiosa bone data for Chinese adult male are provided. Electron absorbed fractions in red bone marrow (RBM) and BE are calculated. Source tissues include the bone marrow (red and yellow), trabecular bone (surfaces and volumes) and cortical bone (surfaces and volumes). Target tissues include RBM and BE. Electron energies range from 10 keV to 10 MeV. Additionally, comparison of the result with other investigations is provided.

  12. Morphological characteristics of monosodium urate: a transmission electron microscopic study of intact natural and synthetic crystals.

    PubMed Central

    Paul, H; Reginato, A J; Schumacher, H R

    1983-01-01

    Transmission electron microscopic studies of synthetic and natural monosodium urate crystals dried on formvar coated grids showed identical internal structures in all crystals. At higher magnification the crystals' surface showed angular or wavy irregularities, and more rarely some crystals appeared to have other tiny crystals on the surface. Protein-like surface coating was not observed except in crystals from one asymptomatic patient in whom synovial fluid was loaded with monosodium urate crystals, but no inflammatory cells were present. Heated synthetic monosodium urate crystals retained the ultrastructural characteristics in their interior but they lost their needle or rod-like shape. Transmission electron microscopic study of monosodium urate crystals dried on formvar coated grids provides a quick method of investigating crystal ultrastructure. Images PMID:6830327

  13. Morphological characteristics of monosodium urate: a transmission electron microscopic study of intact natural and synthetic crystals.

    PubMed

    Paul, H; Reginato, A J; Schumacher, H R

    1983-02-01

    Transmission electron microscopic studies of synthetic and natural monosodium urate crystals dried on formvar coated grids showed identical internal structures in all crystals. At higher magnification the crystals' surface showed angular or wavy irregularities, and more rarely some crystals appeared to have other tiny crystals on the surface. Protein-like surface coating was not observed except in crystals from one asymptomatic patient in whom synovial fluid was loaded with monosodium urate crystals, but no inflammatory cells were present. Heated synthetic monosodium urate crystals retained the ultrastructural characteristics in their interior but they lost their needle or rod-like shape. Transmission electron microscopic study of monosodium urate crystals dried on formvar coated grids provides a quick method of investigating crystal ultrastructure.

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

    PubMed

    Draggan, S

    1976-02-01

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

  15. Is localized infrared spectroscopy now possible in the electron microscope?

    PubMed

    Rez, Peter

    2014-06-01

    The recently developed in-column monochromators make it possible to record energy-c spectra with resolutions better than 30 meV from nanometer-sized regions. It should therefore in principle be possible to detect localized vibrational excitations. The scattering geometry in the electron microscope means that bond stretching in the specimen plane or longitudinal optic phonons dominate the scattering. Most promising for initial studies are vibrations with energies between 300 and 400 meV from hydrogen bonded to other atoms. Estimates of the scattering cross-sections on the basis of a simple model show that they are about the same as inner shell scattering cross-sections. Cross-sections also increase with charge transfer between the atoms, and theory incorporating realistic charge distributions shows that signal/noise is the only limitation to high-resolution imaging. Given the magnitude of the scattering cross-sections, minimizing the tail of the zero-loss peak is just as important as achieving a small-width at half-maximum. Improvements in both resolution and controlling the zero-loss tail will be necessary before it is practical to detect optic phonons in solids between 40 and 60 meV.

  16. Development of compact Cs corrector for desktop electron microscope.

    PubMed

    Chang, Wei-Yu; Chen, Fu-Rong

    2017-08-01

    The desktop Electron Microscopes (desktop EMs) have been commercialized in the recent years, offering a spatial resolution around 1nm in scanning-transmission mode in a routine operation. For the purpose of further improvement in spatial resolution and signal / noise, one may need an aberration corrector with a compact form in order to fit into a desktop EM. In this paper, the permanent magnets with tunable coil are implemented as a transfer lens doublet to realize a compact hexapole corrector for a desktop EM. It will be shown that, with a proper design of permanent magnet transfer lens doublet and hexapole lens, we can generate a negative Cs and avoid the second-order axial astigmatism to reduce the final spot size at the sample plane to be better than 0.5nm for a field emission source. To fulfill with the required condition of a hexapole corrector, a tunable lens is implemented to adjust the magnetic field for compensating the practical error from the permanent magnet. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    PubMed

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

    2006-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  19. [The rat ventricular myocardium in chronic hypercapnia. Electron microscopic study].

    PubMed

    Reichart, E; Moravec, J; Moravec, M; Marotte, F; Hatt, P Y

    1975-11-01

    An electron microscope study of the left ventricular myocardium from rat acclimatized to chronic hypercapnia was done in order to complete the preceding work concerning general effects of respiratory acidosis. After 15 and 30 days of the acclimatation to 8% CO2 no lesions of the myocardium could be found. The results of the morphometric analysis indicated, however, discrete modifications of heart ultrastructure similar to those found before in hypoxic and failing hearts: namely a decrease of mitochondrial mean diameter and a non significant decrease of mitochondrial fractional volume. The latter was accompanied by a significant decrease of myofibrillar mass. The presence of cellular oedema seems to be suggested by an increase of fractional volume of the cytosol. The mechanism of these changes is not easy to explain. Further work will be necessary to make a choice between two possibilities: (1) depressed contractility related to some direct effect of high pCO2 and (2) tissue hypoxia secondary to local effects of the former.

  20. 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.

  1. Visualizing bone porosities using a tabletop scanning electron microscope

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  2. 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.

  3. Contact angle analysis on polymethylmethacrylate and commercial wax by using an environmental scanning electron microscope.

    PubMed

    Brugnara, Marco; Della Volpe, Claudio; Siboni, Stefano; Zeni, Dario

    2006-01-01

    The environmental scanning electron microscope (ESEM) represents one of the most exciting breakthroughs in electron microscopy since the invention of the electron microscope. Its ability to observe uncoated and hydrated samples enhances the possibility for investigating the wettability of surfaces at a microscopic level; by varying the relative vapour pressure or the temperature inside the chamber, it is possible to condense water drops on a micron scale. A large problem in measuring contact angles by ESEM is that the observation angle is not parallel or perpendicular to the surface; thus, the study of the droplets profile using the common algorithms such as spherical approximation or axisymmetric drop shape analysis (ADSA) is not possible, because only a spherical cap shape is commonly observed. In this paper we provide a useful mathematical model to calculate the real contact angle from the initial images. Initially, some simulated spherical caps with different contact and observation angles were created by an appropriate graphic package in order to test the mathematical model. Some real drops obtained by ESEM on wax and polymethylmethacrylate (PMMA) were then studied and the results compared with contact angles measured by common methods on the same materials.

  4. Investigating Dissolution and Precipitation Phenomena with a Smartphone Microscope

    SciTech Connect

    Lumetta, Gregg J.; Arcia, Edgar

    2016-10-11

    A novel smartphone microscope can be used to observe the dissolution and crystallization of sodium chloride at a microscopic level. Observation of these seemingly simple phenomena through the microscope at 100× magnification can actually reveal some surprising behavior. These experiments offer the opportunity to discuss some basic concepts such as how the morphological features of the crystals dictates how the dissolution process proceeds, and how materials can be purified by re-crystallization techniques.

  5. First Results of the Athena Microscopic Imager Investigation

    NASA Technical Reports Server (NTRS)

    Herkenhoff, K.; Squyres, S.; Archinal, B.; Arvidson, R.; Bass, D.; Barrett, J.; Becker, K.; Becker, T.; Bell, J., III; Burr, D.

    2004-01-01

    The Athena science payload on the Mars Exploration Rovers (MER) includes the Microscopic Imager (MI). The MI is a fixed-focus camera mounted on an extendable arm, the Instrument Deployment Device (IDD). The MI acquires images at a spatial resolution of 30 microns/pixel over a broad spectral range (400 - 700 nm). The MI uses the same electronics design as the other MER cameras but its optics yield a field of view of 31 x 31 mm across a 1024 x 1024 pixel CCD image. The MI acquires images using only solar or skylight illumination of the target surface. A contact sensor is used to place the MI slightly closer to the target surface than its best focus distance (about 69 mm), allowing concave surfaces to be imaged in good focus. Coarse focusing (approx. 2 mm precision) is achieved by moving the IDD away from a rock target after contact is sensed. The MI optics are protected from the Martian environment by a retractable dust cover. This cover includes a Kapton window that is tinted orange to restrict the spectral bandpass to 500 - 700 nm, allowing crude color information to be obtained by acquiring images with the cover open and closed. The MI science objectives, instrument design and calibration, operation, and data processing were described by Herkenhoff et al. Initial results of the MI experiment on both MER rovers ('Spirit' and 'Opportunity') are described below.

  6. First Results of the Athena Microscopic Imager Investigation

    NASA Technical Reports Server (NTRS)

    Herkenhoff, K.; Squyres, S.; Archinal, B.; Arvidson, R.; Bass, D.; Barrett, J.; Becker, K.; Becker, T.; Bell, J., III; Burr, D.

    2004-01-01

    The Athena science payload on the Mars Exploration Rovers (MER) includes the Microscopic Imager (MI). The MI is a fixed-focus camera mounted on an extendable arm, the Instrument Deployment Device (IDD). The MI acquires images at a spatial resolution of 30 microns/pixel over a broad spectral range (400 - 700 nm). The MI uses the same electronics design as the other MER cameras but its optics yield a field of view of 31 x 31 mm across a 1024 x 1024 pixel CCD image. The MI acquires images using only solar or skylight illumination of the target surface. A contact sensor is used to place the MI slightly closer to the target surface than its best focus distance (about 69 mm), allowing concave surfaces to be imaged in good focus. Coarse focusing (approx. 2 mm precision) is achieved by moving the IDD away from a rock target after contact is sensed. The MI optics are protected from the Martian environment by a retractable dust cover. This cover includes a Kapton window that is tinted orange to restrict the spectral bandpass to 500 - 700 nm, allowing crude color information to be obtained by acquiring images with the cover open and closed. The MI science objectives, instrument design and calibration, operation, and data processing were described by Herkenhoff et al. Initial results of the MI experiment on both MER rovers ('Spirit' and 'Opportunity') are described below.

  7. Microscopic Theory of Resistive Switching in Ordered Insulators: Electronic vs. Thermal Mechanism.

    PubMed

    Li, Jiajun; Aron, Camille; Kotliar, Gabriel; Han, Jong E

    2017-04-10

    We investigate the dramatic switch of resistance in ordered correlated insulators, when driven out of equilibrium by a strong voltage bias. Microscopic calculations on a driven-dissipative lattice of interacting electrons explain the main experimental features of resistive switching (RS), such as the hysteretic $I$-$V$ curves and the formation of hot conductive filaments. The energy-resolved electron distribution at the RS reveals the underlying nonequilibrium electronic mechanism, namely Landau-Zener tunneling, and also justifies a thermal description where the hot-electron temperature, estimated from the first moment of the distribution, matches the equilibrium phase transition temperature. We discuss the tangled relationship between filament growth and negative differential resistance, and the influence of crystallographic structure and disorder in the RS.

  8. Autofocus on moving object in scanning electron microscope.

    PubMed

    Kudryavtsev, Andrey V; Dembélé, Sounkalo; Piat, Nadine

    2017-07-12

    The sharpness of the images coming from a Scanning Electron Microscope (SEM) is a very important property for many computer vision applications at micro- and nanoscale. It represents how much object details are distinctive in the images: the object may be perceived sharp or blurred. Image sharpness highly depends on the value of focal distance, or working distance in the case of the SEM. Autofocus is the technique allowing to automatically adjust the working distance to maximize the sharpness. Most of the existing algorithms allows working only with a static object which is enough for the tasks of visualization, manual microanalysis or microcharacterization. These applications work with a low frame rate, less than 1 Hz, that guarantees a low level of noise. However, static autofocus can not be used for samples performing continuous 3D motion, which is the case of robotic applications where it is required to carry out a continuous 3D position measurement, e.g., nano-assembly or nanomanipulation. Moreover, in addition to constantly keeping object in focus while it is moving, it is required to perform the operation at high frame rate. The approach offering both these possibilities is presented in this paper and is referred as dynamic autofocus. The presented solution is based on stochastic optimization techniques. It allows tracking the maximum of the sharpness of the images without sweep and without training. It works under uncertainty conditions: presence of noise in images, unknown maximal sharpness and unknown 3D motion of the specimen. The experiments, that were performed with noisy images at high frame rate (5 Hz), were conducted on a Carl Zeiss Auriga 60 FE-SEM. They prove the robustness of the algorithm with respect to the variation of optimization parameters, object speed and magnification. Moreover, it is invariant to the object structure and its variation in time. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. An Electron Microscope Study of the Rat Ovum

    PubMed Central

    Sotelo, J. Roberto; Porter, Keith R.

    1959-01-01

    This paper reports on the fine structure of rat oocytes at stages before ovulation, during maturation, fertilization, and early cleavage. The study includes parallel observations on light and electron microscope preparations with attempted correlations. The follicular cells of the ovarian egg are described as sending long processes through the zona pellucida to the egg surface where they mingle with thin projections from the egg itself. No open communication between follicle cell cytoplasm and egg cytoplasm was observed. During maturation and fertilization both types of processes are withdrawn from the zona. The germinal vesicle and later the pronuclei of the fertilized egg are characterized by numerous large nucleoli. These have the form of thick walled vesicles with diameters as great as 8 to 10 µ. The wall is dense in the EM image and appears to consist in part of small granules. The cytoplasm shows several inclusions including mitochondria of usual form and a Golgi component which has the typical fine structure and the distribution described by earlier light studies. Small dense particles, presumably RNP particles, are distributed throughout the cytoplasmic matrix and show no preference for membranes. The endoplasmic reticulum of the oocyte is represented by a scattering only of vesicles, but begins a more extensive and elaborate development with the onset of segmentation. One inclusion of the ooplasm, similar in size to mitochondria, receives special attention. It is a vesicular structure, containing a large number of small vesicles (10 to 50 mµ in diameter) and frequently a central density or nucleoid. They are referred to as multivesicular bodies. Such bodies are found in small number in the ovarian egg, but increase greatly in number during maturation and fertilization. It appears from the micrographs of eggs in these latter stages that these vesicular bodies break down and liberate their content of small vesicles to the surrounding ooplasm. Comments are

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

    SciTech Connect

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

    2013-04-08

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

  11. 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.

  12. 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…

  13. 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…

  14. 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

  15. Brewster Angle Microscope Investigations of Two Dimensional Phase Transitions

    NASA Astrophysics Data System (ADS)

    Schuman, Adam William

    The liquid-liquid interface is investigated by microscopic and thermodynamic means to image and measure interfacial properties when the system undergoes a two-dimensional (2D) phase transition of a Gibbs monolayer by varying the sample temperature. An in-house Brewster angle microscope (BAM) is constructed to visualize the interface during this transition while a quasi-elastic light scattering technique is used to determine the interfacial tension. These results complement x-ray investigations of the same systems. Evidence of interfacial micro-separated structure, microphases, comes from observations across a hexane-water interface with the inclusion of a long-chain fluorinated alcohol surfactant into the bulk hexane. Microphases take the form of spatially modulated structure to the density of the surfactant as it spans laterally across the interface. The surfactant monolayer exhibits microphase morphology over a range of a couple degrees as the temperature of the system is scanned through the 2D gas-solid phase transition. Microphase structure was observed for heating and cooling the hexane-water system and structural comparisons are given when the temperature step and quench depth of the cooling process is varied. A complete sequence of morphological structure was observed from 2D gas to cluster to labyrinthine stripe to a 2D solid mosaic pattern. Two characteristic length scales emerge giving rise to speculation of an elastic contribution to the standard repulsive and attractive competitive forces stabilizing the microphase. The benefit of BAM to laterally image very thin films across the surface of an interface on the micrometer length scale nicely complements x-ray reflectivity methods that average structural data transverse to the liquid interface on a molecular scale. To properly analyze x-ray reflectivity data, the interface is required to be laterally homogeneous. BAM can sufficiently characterize the interface for this purpose as is done for a Langmuir

  16. Environmental Scanning Electron Microscope Imaging of Vesicle Systems.

    PubMed

    Perrie, Yvonne; Ali, Habib; Kirby, Daniel J; Mohammed, Afzal U R; McNeil, Sarah E; Vangala, Anil

    2017-01-01

    The structural characteristics of liposomes have been widely investigated and there is certainly a strong understanding of their morphological characteristics. Imaging of these systems, using techniques such as freeze-fracturing methods, transmission electron microscopy, and cryo-electron imaging, has allowed us to appreciate their bilayer structures and factors which can influence this. However, there are few methods which all us to study these systems in their natural hydrated state; commonly the liposomes are visualized after drying, staining, and/or fixation of the vesicles. Environmental Scanning Electron Microscopy (ESEM) offers the ability to image a liposome in its hydrated state without the need for prior sample preparation. Within our studies we were the first to use ESEM to study liposomes and niosomes and we have been able to dynamically follow the hydration of lipid films and changes in liposome suspensions as water condenses on to, or evaporates from, the sample in real time. This provides insight into the resistance of liposomes to coalescence during dehydration, thereby providing an alternative assay of liposome formulation and stability.

  17. Fractal evaluation of drug amorphicity from optical and scanning electron microscope images

    NASA Astrophysics Data System (ADS)

    Gavriloaia, Bogdan-Mihai G.; Vizireanu, Radu C.; Neamtu, Catalin I.; Gavriloaia, Gheorghe V.

    2013-09-01

    Amorphous materials are metastable, more reactive than the crystalline ones, and have to be evaluated before pharmaceutical compound formulation. Amorphicity is interpreted as a spatial chaos, and patterns of molecular aggregates of dexamethasone, D, were investigated in this paper by using fractal dimension, FD. Images having three magnifications of D were taken from an optical microscope, OM, and with eight magnifications, from a scanning electron microscope, SEM, were analyzed. The average FD for pattern irregularities of OM images was 1.538, and about 1.692 for SEM images. The FDs of the two kinds of images are less sensitive of threshold level. 3D images were shown to illustrate dependence of FD of threshold and magnification level. As a result, optical image of single scale is enough to characterize the drug amorphicity. As a result, the OM image at a single scale is enough to characterize the amorphicity of D.

  18. Apparatus and methods for controlling electron microscope stages

    SciTech Connect

    Duden, Thomas

    2015-08-11

    Methods and apparatus for generating an image of a specimen with a microscope (e.g., TEM) are disclosed. In one aspect, the microscope may generally include a beam generator, a stage, a detector, and an image generator. A plurality of crystal parameters, which describe a plurality of properties of a crystal sample, are received. In a display associated with the microscope, an interactive control sphere based at least in part on the received crystal parameters and that is rotatable by a user to different sphere orientations is presented. The sphere includes a plurality of stage coordinates that correspond to a plurality of positions of the stage and a plurality of crystallographic pole coordinates that correspond to a plurality of polar orientations of the crystal sample. Movement of the sphere causes movement of the stage, wherein the stage coordinates move in conjunction with the crystallographic coordinates represented by pole positions so as to show a relationship between stage positions and the pole positions.

  19. Diffusion length measurement using the scanning electron microscope. [for silicon solar cell

    NASA Technical Reports Server (NTRS)

    Weizer, V. G.

    1975-01-01

    The present work describes a measuring technique employing the scanning electron microscope in which values of the true bulk diffusion length are obtained. It is shown that surface recombination effects can be eliminated through application of highly doped surface field layers. The effects of high injection level and low-high junction current generation are investigated. Results obtained with this technique are compared to those obtained by a penetrating radiation (X-ray) method, and a close agreement is found. The SEM technique is limited to cells that contain a back surface field layer.

  20. Microscopic investigations in a diabetic rat urinary bladder infected with Trichosomoides crassicauda.

    PubMed

    Ozkorkmaz, Ebru Gokalp

    2011-01-01

    Rats are widely used laboratory animals and have several parasites. One of these are helminths, known not only to cause serious effects on the experimental results in healthy subjects, but also in subjects with heavy infections. One of the relatively pathologic helminth is Trichosomoides crassicauda, which lives in the nodules of the urinary bladder. It is known that diabetics are more prone to infections with several microorganisms. Observations in a diabetic rat bladder showed T. crassicauda eggs inside the transitional epithelium, and structural changes in the bladder epithelium were evident. Urinary-bladder tissues taken from streptozotocin-injected diabetic subjects and citrate buffer-injected control subjects were fixed, embedded in araldite and investigated under a light microscope. Distinct changes in the histological structure of a diabetic urinary bladder transitional epithelium were observed after T. crassicauda infection. Many papillomas were formed and the epithelial tissues were completely degenerated. In addition, electron microscopic examinations also revealed degeneration of the subepithelial tissues.

  1. Single-electron tunneling. [Microwave scanning tunneling microscope

    SciTech Connect

    Ruggiero, S.T.

    1993-01-01

    Pictures using the low-temperature microwave scanning tunneling microscope, have been made of particles and tunneling IV characteristics determined. Strong, sometimes periodic negative differential resistance was observed in small-particle systems. Au and Ag droplets and particles were studied. 4 figs.

  2. Imaging single atoms using secondary electrons with an aberration-corrected electron microscope.

    PubMed

    Zhu, Y; Inada, H; Nakamura, K; Wall, J

    2009-10-01

    Aberration correction has embarked on a new frontier in electron microscopy by overcoming the limitations of conventional round lenses, providing sub-angstrom-sized probes. However, improvement of spatial resolution using aberration correction so far has been limited to the use of transmitted electrons both in scanning and stationary mode, with an improvement of 20-40% (refs 3-8). In contrast, advances in the spatial resolution of scanning electron microscopes (SEMs), which are by far the most widely used instrument for surface imaging at the micrometre-nanometre scale, have been stagnant, despite several recent efforts. Here, we report a new SEM, with aberration correction, able to image single atoms by detecting electrons emerging from its surface as a result of interaction with the small probe. The spatial resolution achieved represents a fourfold improvement over the best-reported resolution in any SEM (refs 10-12). Furthermore, we can simultaneously probe the sample through its entire thickness with transmitted electrons. This ability is significant because it permits the selective visualization of bulk atoms and surface ones, beyond a traditional two-dimensional projection in transmission electron microscopy. It has the potential to revolutionize the field of microscopy and imaging, thereby opening the door to a wide range of applications, especially when combined with simultaneous nanoprobe spectroscopy.

  3. Contrast curves for low energy electron exposures of an EUV resist in a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Bhattarai, Suchit; Neureuther, Andrew R.; Naulleau, Patrick P.

    2017-03-01

    We present an experimental technique for determining the energy delivery efficiency of secondary electrons in an EUV resist, by directly exposing a positive tone chemically amplified resist with 29- 91 eV electrons created by utilizing the deceleration technology in a scanning electron microscope. Charging is an important problem associated with thin film exposure experiments. We assess the feasibility of using the SEM frame rate as a knob for controlling charging related artifacts. Preliminary measurements of secondary electron emission signal from an unexposed region in the resist provide clues about the time domain surface potentials that may form while the sample charges during exposures. These signals are found to change as a function of the SEM frame rate and landing energies. We provide contrast curve data for resist exposures with 29 eV, 49 eV and 91 eV electrons at three frame rates of 33 ms/frame, 8 s/frame and 30 s/frame. The energy delivery efficiency of electrons estimated for all three frame rates are also provided.

  4. 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.

  5. 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.

  6. Reflection electron energy-loss spectroscopy and imaging for surface studies in transmission electron microscopes.

    PubMed

    Wang, Z L; Bentley, J

    1992-02-15

    A review is given on the techniques and applications of high-energy reflection electron energy-loss spectroscopy (REELS) and reflection electron microscopy (REM) for surface studies in scanning transmission electron microscopes (STEM) and conventional transmission electron microscopes (TEM). A diffraction method is introduced to identify a surface orientation in the geometry of REM. The surface dielectric response theory is presented and applied for studying alpha-alumina surfaces. Domains of the alpha-alumina (012) surface initially terminated with oxygen can be reduced by an intense electron beam to produce Al metal; the resistance to beam damage of surface domains initially terminated with Al+3 ions is attributed to the screening effect of adsorbed oxygen. Surface energy-loss near-edge structure (ELNES), extended energy-loss fine structure (EXELFS), and microanalysis using REELS are illustrated based on the studies of TiO2 and MgO. Effects of surface resonances (or channeling) on the REELS signal-to-background ratio are described. The REELS detection of a monolayer of oxygen adsorption on diamond (111) surfaces is reported. It is shown that phase contrast REM image content can be significantly increased with the use of a field emission gun (FEG). Phase contrast effects close to the core of a screw dislocation are discussed and the associated Fresnel fringes around a surface step are observed. Finally, an in situ REM experiment is described for studying atomic desorption and diffusion processes on alpha-alumina surfaces at temperatures of 1,300-1,400 degrees C.

  7. Analytical electron microscope based on scanning transmission electron microscope with wavelength dispersive x-ray spectroscopy to realize highly sensitive elemental imaging especially for light elements

    NASA Astrophysics Data System (ADS)

    Koguchi, Masanari; Tsuneta, Ruriko; Anan, Yoshihiro; Nakamae, Koji

    2017-01-01

    An analytical electron microscope based on the scanning transmission electron microscope with wavelength dispersive x-ray spectroscopy (STEM-WDX) to realize highly sensitive elemental imaging especially for light elements has been developed. In this study, a large-solid-angle multi-capillary x-rays lens with a focal length of 5 mm, long-time data acquisition (e.g. longer than 26 h), and a drift-free system made it possible to visualize boron-dopant images in a Si substrate at a detection limit of 0.2 atomic percent.

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

    PubMed

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

    2011-06-01

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

  9. In situ conversion of nanostructures from solid to hollow in transmission electron microscopes using electron beam.

    PubMed

    El Mel, Abdel-Aziz; Bittencourt, Carla

    2016-06-07

    With the current development of electron beam sources, the use of transmission electron microscopes is no more limited to imaging or chemical analysis but has rather been extended to nanoengineering. This includes the e-beam induced growth, etching and structural transformation of nanomaterials. In this review we summarize recent progress on the e-beam induced morphological transformation of nanostructures from solid to hollow. We provide a detailed account of the processes reported so far in the literature with a special emphasis on the mechanistic understanding of the e-beam induced hollowing of nanomaterials. Through an important number of examples, we discuss how one can achieve a precise control of such hollowing processes by understanding the fundamental mechanisms occurring at the atomic scale during the irradiation of solid nanostructures. Finally, we conclude with remarks and our own view on the prospective future directions of this research field.

  10. 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.

  11. Comparison of the myotoxic effects of levobupivacaine, bupivacaine, and ropivacaine: an electron microscopic study.

    PubMed

    Öz Gergin, Özlem; Yıldız, Karamehmet; Bayram, Adnan; Sencar, Leman; Coşkun, Gülfidan; Yay, Arzu; Biçer, Cihangir; Özdamar, Saim; Polat, Sait

    2015-05-01

    The aim of this study was to investigate the myotoxic effects of bupivacaine, ropivacaine, and levobupivacaine which were applied intramuscularly to rat skeletal muscle. Forty Wistar-Albino rats were divided into four groups. In the study, .5% bupivacaine (Group B), .5% ropivacaine (Group R), .5% levobupivacaine (Group L), or .9% normal saline (Group SF) was applied intramuscularly to the right gastrocnemius muscle of rats. The rats in each group were sacrificed on the second day after injection. Sections of muscle samples were stained with hematoxylin-eosin for light microscopic investigation and prepared for the evaluation of ultrastructural changes in the subcellular level with transmission electron microscopy. All three local anesthetic agents caused qualitatively similar skeletal muscle damage. The most observed muscle damage was in Group B, muscle damage of Group R was less than that of Group B, and the least damage was seen in Group L quantitatively. Electron microscopic examination of each group that caused cellular damage was qualitatively similar. The most subcellular damage was observed in the group receiving bupivacaine, less was seen in the ropivacaine group, and the least was observed in the levobupivacaine group. The results indicated that bupivacaine caused more myotoxic damage than the other two agents in the skeletal muscle of rats and that levobupivacaine caused less myotoxic damage than both bupivacaine and ropivacaine at the cell and tissue levels.

  12. Naturally Occurring Immune-Complex Glomerulonephritis in Cynomolgus Monkeys (Macaca irus). I. Light, Immunofluorescence, and Electron Microscopic Studies.

    DTIC Science & Technology

    IMMUNOGLOBULINS, *VETERINARY MEDICINE, *MONKEYS, PATHOLOGY, FLUORESCENT ANTIBODY TECHNIQUES, DISEASES , GAMMA GLOBULIN, ANTIGENS, ANTIBODIES, HISTOLOGY, ETIOLOGY, ELECTRON MICROSCOPY, MICROSCOPES, IMMUNOLOGY.

  13. Advanced imaging microscope tools applied to microgravity research investigations

    NASA Astrophysics Data System (ADS)

    Peterson, L.; Samson, J.; Conrad, D.; Clark, K.

    1998-01-01

    The inability to observe and interact with experiments on orbit has been an impediment for both basic research and commercial ventures using the shuttle. In order to open the frontiers of space, the Center for Microgravity Automation Technology has developed a unique and innovative system for conducting experiments at a distance, the ``Remote Scientist.'' The Remote Scientist extends laboratory automation capability to the microgravity environment. While the Remote Scientist conceptually encompasses a broad spectrum of elements and functionalities, the development approach taken is to: • establish a baseline capability that is both flexible and versatile • incrementally augment the baseline with additional functions over time. Since last year, the application of the Remote Scientist has changed from protein crystal growth to tissue culture, specifically, the development of skeletal muscle under varying levels of tension. This system includes a series of bioreactor chambers that allow for three-dimensional growth of muscle tissue on a membrane suspended between the two ends of a programmable force transducer that can provide automated or investigator-initiated tension on the developing tissue. A microscope objective mounted on a translation carriage allows for high-resolution microscopy along a large area of the tissue. These images will be mosaiced on orbit to detect features and structures that span multiple images. The use of fluorescence and pseudo-confocal microscopy will maximize the observational capabilities of this system. A series of ground-based experiments have been performed to validate the bioreactor, the force transducer, the translation carriage and the image acquisition capabilities of the Remote Scientist. • The bioreactor is capable of sustaining three dimensional tissue culture growth over time. • The force transducer can be programmed to provide static tension on cells or to simulate either slow or fast growth of underlying tissues in

  14. Improved Specimen Coating Technique for Scanning Electron Microscope Observation of Decomposer Microorganisms 1

    PubMed Central

    Draggan, Sidney

    1976-01-01

    Sputter coating of leaf litter microbe samples provides scanning electron microscope images with greater information content than either vacuum evaporation of thin metal coatings or tissue conductance. Images PMID:16345150

  15. In situ fatigue loading stage inside scanning electron microscope

    NASA Technical Reports Server (NTRS)

    Telesman, Jack; Kantzos, Peter; Brewer, David

    1988-01-01

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

  16. The Microstructure of Cellulose Nanocrystal Aerogels as Revealed by Transmission Electron Microscope Tomography.

    PubMed

    Buesch, Christian; Smith, Sean W; Eschbach, Peter; Conley, John F; Simonsen, John

    2016-09-12

    The microstructure of highly porous cellulose nanocrystal (CNC) aerogels is investigated via transmission electron microscope (TEM) tomography. The aerogels were fabricated by first supercritically drying a carboxylated CNC organogel and then coating via atomic layer deposition with a thin conformal layer of Al2O3 to protect the CNCs against prolonged electron beam exposure. A series of images was then acquired, reconstructed, and segmented in order to generate a three-dimensional (3D) model of the aerogel. The model agrees well with theory and macroscopic measurements, indicating that a thin conformal inorganic coating enables TEM tomography as an analysis tool for microstructure characterization of CNC aerogels. The 3D model also reveals that the aerogels consist of randomly orientated CNCs that attach to one another primarily in three ways: end to end contact, "T″ contact, and "X″ contact.

  17. On the optical stability of high-resolution transmission electron microscopes.

    PubMed

    Barthel, J; Thust, A

    2013-11-01

    In the recent two decades the technique of high-resolution transmission electron microscopy experienced an unprecedented progress through the introduction of hardware aberration correctors and by the improvement of the achievable resolution to the sub-Ångström level. The important aspect that aberration correction at a given resolution requires also a well defined amount of optical stability has received little attention so far. Therefore we investigate the qualification of a variety of high-resolution electron microscopes to maintain an aberration corrected optical state in terms of an optical lifetime. We develop a comprehensive statistical framework for the estimation of the optical lifetime and find remarkably low values between tens of seconds and a couple of minutes. Probability curves are introduced, which inform the operator about the chance to work still in the fully aberration corrected state.

  18. An alternative to the flat substrate method of preparing electron microscope autoradiographs.

    PubMed

    Ball, A K; Tidball, J G; Dickson, D H

    1981-07-01

    Difficulty with flat substrate methods of preparing electron microscope autoradiographs has prompted reconsideration and refinement of a technique in which an electron microscope grid is placed beneath the specimen prior to dipping. This technique avoids the problems commonly associated with the direct application of emulsions to specimen grids, and should be considered as an alternative to flat substrate techniques when difficulty with these methods is encountered.

  19. In Situ Electronic Characterization of Graphene Nanoconstrictions Fabricated in a Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Lu, Ye; Merchant, Christopher; Drndic, Marija; Johnson, A. T. Charlie

    2012-02-01

    We report electronic measurements on high quality graphene nanoconstrictions (GNCs) fabricated in a transmission electron microscope (TEM), and the first measurements on GNC conductance with an accurate measurement of constriction width down to 1 nm. To create the GNCs, freely suspended graphene ribbons were fabricated using few-layer graphene grown by chemical vapor deposition. The ribbons were loaded into the TEM, and a current-annealing procedure was used to clean the material and improve its electronic characteristics. The TEM beam was then used to sculpt GNCs to a series of desired widths in the range 1-700 nm; after each sculpting step, the sample was imaged by TEM and its electronic properties were measured in situ. GNC conductance was found to be remarkably high, comparable to that of exfoliated graphene samples of similar size. The GNC conductance varied with width approximately as G(w) = (e^2/h)w^0.75, where w is the constriction width in nanometers. GNCs support current densities greater than 120 μA/nm^2, 2 orders of magnitude higher than that which has been previously reported for graphene nanoribbons and 2000 times higher than that reported for copper.

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

    PubMed

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

    2016-08-01

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

  1. In situ electronic characterization of graphene nanoconstrictions fabricated in a transmission electron microscope.

    PubMed

    Lu, Ye; Merchant, Christopher A; Drndić, Marija; Johnson, A T Charlie

    2011-12-14

    We report electronic measurements on high-quality graphene nanoconstrictions (GNCs) fabricated in a transmission electron microscope (TEM), and the first measurements on GNC conductance with an accurate measurement of constriction width down to 1 nm. To create the GNCs, freely suspended graphene ribbons were fabricated using few-layer graphene grown by chemical vapor deposition. The ribbons were loaded into the TEM, and a current-annealing procedure was used to clean the material and improve its electronic characteristics. The TEM beam was then used to sculpt GNCs to a series of desired widths in the range 1-700 nm; after each sculpting step, the sample was imaged by TEM and its electronic properties were measured in situ. GNC conductance was found to be remarkably high, comparable to that of exfoliated graphene samples of similar size. The GNC conductance varied with width approximately as G(w)=(e2/h)w0.75, where w is the constriction width in nanometers. GNCs support current densities greater than 120 μA/nm2, 2 orders of magnitude higher than that which has been previously reported for graphene nanoribbons and 2000 times higher than that reported for copper.

  2. Micro-Scanning Electron Microscope and X-ray Spectrometer for Planetary Exploration

    NASA Astrophysics Data System (ADS)

    Blake, D. F.; Nguyen, C. V.; Dholakia, G.; Ribaya, B. P.; Niemann, D.; Ngo, V.; McKenzie, C.; Rahman, M.; Alam, A.; Joy, D.; Espinosa, B.

    2007-12-01

    Scanning Electron Microscopy combined with electron-induced X-ray Fluorescence Spectroscopy (SEM-EDX) is one of the most powerful techniques for characterizing surface morphology and composition with spatial resolution of a micrometer or better. SEM-EDX can elucidate natural processes such as low-temperature diagenesis, thermal or pressure induced metamorphism, volcanism/magmatism, atmosphere/crust interaction and the like. This information is useful for the investigation of the natural history of solar system objects. We are developing a prototype micromachined scanning electron microscope with X-ray spectrometer (MSEMS) for solar system exploration. The MSEMS is comprised of a carbon nanotube field emission (CNTFE) electron source integrated with a micro-electro-mechanical-system (MEMS) based electron gun and electron optics structure. The MSEMS system will utilize a piezoelectric sample stage, having scan ranges from a few angstroms to several hundreds of microns. Compared with conventional electron sources, the CNTFE source offers advantages of low power usage, ultra-small source size and simplicity of electrostatic focusing. The MSEMS instrument, including CNTFE source, MEMS electron optic column and piezoelectric sample stage, is envisioned to be 1-2 cm in height and will operate in the range of 500 eV to 15 KeV. The imaging resolution of MEMS is predicted to be ~10 nm at 5 KeV and the spatial resolution of the X-ray spectrometer will be ~1 μm at 15 KeV. We will present field emission data from our CNTFE source as well as the MEMS electron gun and piezostage designs.

  3. Investigation of Microscopic Materials Limitations of Superconducting RF Cavities

    SciTech Connect

    Anlage, Steven

    2014-07-23

    The high-field performance of SRF cavities is often limited by breakdown events below the intrinsic limiting surface fields of Nb, and there is abundant evidence that these breakdown events are localized in space inside the cavity. Also, there is a lack of detailed understanding of the causal links between surface treatments and ultimate RF performance at low temperatures. An understanding of these links would provide a clear roadmap for improvement of SRF cavity performance, and establish a cause-and-effect ‘RF materials science’ of Nb. We propose two specific microscopic approaches to addressing these issues. First is a spatially-resolved local microwave-microscope probe that operates at SRF frequencies and temperatures to discover the microscopic origins of breakdown, and produce quantitative measurements of RF critical fields of coatings and films. Second, RF Laser Scanning Microscopy (LSM) has allowed visualization of RF current flow and sources of nonlinear RF response in superconducting devices with micro-meter spatial resolution. The LSM will be used in conjunction with surface preparation and characterization techniques to create definitive links between physical and chemical processing steps and ultimate cryogenic microwave performance. We propose to develop RF laser scanning microscopy of small-sample Nb pieces to establish surface-processing / RF performance relations through measurement of RF current distributions on micron-length scales and low temperatures.

  4. Unveiling nanometric plasmons optical properties with advanced electron spectroscopy in the Scanning Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Kociak, Mathieu

    Since the pioneering work of Yamamoto, the use of electron spectroscopy such as Cathodoluminescence (CL) and Electron Energy Loss Spectroscopy (EELS) in a Scanning (Transmission) Electron Microscope (STEM) has considerably helped improving our understanding of the optical properties of metallic nanoparticles. The resemblance of spectroscopic signals from electron and pure optical techniques leads to the intuition that both types of techniques are very close, an idea theoretically discussed by F.J. Garcia de Abajo and coworkers. However, it is also quite intuitive that CL and EELS should be different. For example, EELS helps detecting any sort of modes while CL can only detect radiative ones. On the other hand, even between optical spectroscopy techniques, clear differences such as energy shifts or spectral shapes changes are expected in the case of plasmons. The lack of adapted instrumentation capable of performing combined EELS and CL, as well as theoretical developments allowing to account for the generic difference between EELS and CL and their optical counterparts impeached a comprehensive understanding of plasmons physics with the otherwise amazing electron spectroscopies. In this talk, I will present recent experimental results showing combined EELS and CL spectral mapping of plasmonic properties for nanoparticles with several shapes (triangles, cubes, stars...) and composition (gold, silver, aluminum...). Helped with different theoretical tools, I will try to show how these results can be related to their optical counterparts (extinction, scattering), and what type of physical insights can be gained from these combined measurements. Finally, if time allows, pointing the weaknesses of state-of-the-art CL and EELS (in terms of spectral range and/or spectral resolution), I will present EELS results obtained on highly monochromated electron beams that could cope with these limitations

  5. Electronic Single Molecule Measurements with the Scanning Tunneling Microscope

    NASA Astrophysics Data System (ADS)

    Im, Jong One

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

  6. Three-dimensional numerical analysis of mixed ionic and electronic conducting cathode reconstructed by focused ion beam scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Matsuzaki, Katsuhisa; Shikazono, Naoki; Kasagi, Nobuhide

    2011-03-01

    Three-dimensional microstructure of mixed ionic and electronic conducting cathode, La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF6428), is obtained by a dual-beam focused ion beam-scanning electron microscope, and its overpotential is predicted by the lattice Boltzmann method. Gaseous, ionic and electronic transport equations coupled with electrochemical reaction at the gas/solid interface in the three-dimensional microstructure are solved with an assumption of local equilibrium in the solid oxide. The gas transport is modeled by the dusty gas model. The numerical simulation is conducted under the current density conditions of 0.01, 0.05, 0.1 and 0.2 A/cm2. Predicted cathode overpotentials agreed well with the experimental results. However, predicted overpotential was very large at O2 = 20%, T = 973 K and i = 0.2 A/cm2 case due to the decline of ionic conductivity at low oxygen partial pressure. Three-dimensional chemical potential and current vector distributions inside LSCF microstructure are presented. Ionic and electronic current stream lines are uniform and smooth, which indicates good ionic and electronic conductions as well as wide electrochemically active areas inside the LSCF microstructure. Present method will be an effective tool for investigating local oxygen potential field which affects local reactions, diffusions and physical properties of the MIEC cathodes.

  7. On the threshold conditions for electron beam damage of asbestos amosite fibers in the transmission electron microscope (TEM).

    PubMed

    Martin, Joannie; Beauparlant, Martin; Sauvé, Sébastien; L'Espérance, Gilles

    2016-12-01

    Asbestos amosite fibers were investigated to evaluate the damage caused by a transmission electron microscope (TEM) electron beam. Since elemental x-ray intensity ratios obtained by energy dispersive x-ray spectroscopy (EDS) are commonly used for asbestos identification, the impact of beam damage on these ratios was evaluated. It was determined that the magnesium/silicon ratio best represented the damage caused to the fiber. Various tests showed that most fibers have a current density threshold above which the chemical composition of the fiber is modified. The value of this threshold current density varied depending on the fiber, regardless of fiber diameter, and in some cases could not be determined. The existence of a threshold electron dose was also demonstrated. This value was dependent on the current density used and can be increased by providing a recovery period between exposures to the electron beam. This study also established that the electron beam current is directly related to the damage rate above a current density of 165 A/cm(2). The large number of different results obtained suggest, that in order to ensure that the amosite fibers are not damaged, analysis should be conducted below a current density of 100 A/cm(2).

  8. Scanning electron microscope studies of human metaphase chromosomes.

    PubMed

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

    2014-03-06

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

  9. [The cholesterol content of biomembranes (an electron microscopic study)].

    PubMed

    Gusev, S A; Povaliĭ, T M; Baryshnikova, N A

    1995-01-01

    A new specific cholesterol marker and scanning electron microscopy were used to study the quantity and distribution of cholesterol in the artifical phospholipid membranes and in the plasmalemma of animal and human endotheliocyte and erythrocytes in health and in hypercholesterolemia.

  10. Centrifugal sedimentation of virus particles for electron microscopic counting.

    PubMed

    Mathews, J; Buthala, D A

    1970-05-01

    Centrifuge cells with conical chambers were provided by using special inserts for the stainless-steel tubes that fit the Spinco SW-39 rotor. Particulate material, centrifuged in these cells, was collected on carbon-coated glass discs. These discs were exposed to OsO(4) vapor, dehydrated in graded alcohols, air-dried, and metal-shadowed. The metal-shadowed carbon film was floated from the glass, mounted on a grid, and examined. A knowledge of cell geometry and microscope magnification allowed correlation of the number of particles observed to a volume of the original suspension. A precision of +/-6% at the 95% confidence level was attained when counting approximately 100 particles per 10,000 x field. Applications and advantages of the method are discussed.

  11. Automatic system for electron tomography data collection in the ultra-high voltage electron microscope.

    PubMed

    Cao, Meng; Nishi, Ryuji; Wang, Fang

    2017-09-12

    In this study, we report an automatic system for collection of tilt series for electron tomography based on the ultra-HVEM in Osaka University. By remotely controlling the microscope and reading the observation image, the system can track the field of view and do focus in each tilt angle. The automatic tracking is carried out with an image matching technique based on normalized correlation coefficient. Auto focus is realized by the optimization of image sharpness. A toolkit that can expand the field of view with technique of image stitching is also developed. The system can automatically collect the tilt series with much smaller time consumption. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    PubMed

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

    2017-10-01

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

  13. 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

  14. Electronic structure of hydrogenated diamond: Microscopical insight into surface conductivity

    NASA Astrophysics Data System (ADS)

    Iacobucci, S.; Alippi, Paola; Calvani, P.; Girolami, M.; Offi, F.; Petaccia, L.; Trucchi, D. M.

    2016-07-01

    We have correlated the surface conductivity of hydrogen-terminated diamond to the electronic structure in the Fermi region. Significant density of electronic states (DOS) in proximity of the Fermi edge has been measured by photoelectron spectroscopy (PES) on surfaces exposed to air, corresponding to a p -type electric conductive regime, while upon annealing a depletion of the DOS has been achieved, resembling the diamond insulating state. The surface and subsurface electronic structure has been determined, exploiting the different probing depths of PES applied in a photon energy range between 7 and 31 eV. Ab initio density functional calculations including surface charge depletion and band-bending effects favorably compare with electronic states measured by angular-resolved photoelectron spectroscopy. Such states are organized in the energy-momentum space in a twofold structure: one, bulk-derived, band disperses in the Γ -X direction with an average hole effective mass of (0.43 ±0.02 ) m0 , where m0 is the bare electron mass; a second flatter band, with an effective mass of (2.2 ±0.9 ) m0 , proves that a hole gas confined in the topmost layers is responsible for the conductivity of the (2 ×1 ) hydrogen-terminated diamond (100 ) surface.

  15. Transmission electron microscopic examination of phosphoric acid fuel cell components

    NASA Technical Reports Server (NTRS)

    Pebler, A.

    1986-01-01

    Transmission electron microscopy (TEM) was used to physically characterize tested and untested phosphoric acid fuel cell (PAFC) components. Those examined included carbon-supported platinum catalysts, carbon backing paper, and Teflon-bonded catalyst layers at various stages of fabrication and after testing in pressurized PAFC's. Applicability of electron diffraction and electron energy loss spectroscopy for identifying the various phases was explored. The discussion focuses on the morphology and size distribution of platinum, the morphology and structural aspects of Teflon in catalyst layers, and the structural evidence of carbon corrosion. Reference is made to other physical characterization techniques where appropriate. A qualitative model of the catalyst layer that emerged from the TEM studies is presented.

  16. Microscopic theory of electron absorption by plasma-facing surfaces

    NASA Astrophysics Data System (ADS)

    Bronold, F. X.; Fehske, H.

    2017-01-01

    We describe a method for calculating the probability with which the wall of a plasma absorbs an electron at low energy. The method, based on an invariant embedding principle, expresses the electron absorption probability as the probability for transmission through the wall’s long-range surface potential times the probability to stay inside the wall despite of internal backscattering. To illustrate the approach we apply it to a SiO2 surface. Besides emission of optical phonons inside the wall we take elastic scattering at imperfections of the plasma-wall interface into account and obtain absorption probabilities significantly less than unity in accordance with available electron-beam scattering data but in disagreement with the widely used perfect absorber model.

  17. On the interpretation of electron microscopic maps of biological macromolecules.

    PubMed

    Wang, Jimin; Moore, Peter B

    2017-01-01

    The images of flash-frozen biological macromolecules produced by cryo-electron microscopy (EM) can be used to generate accurate, three-dimensional, electric potential maps for these molecules that resemble X-ray-derived electron density maps. However, unlike electron density maps, electric potential maps can include negative features that might for example represent the negatively charged, backbone phosphate groups of nucleic acids or protein carboxylate side chains, which can complicate their interpretation. This study examines the images of groups that include charged atoms that appear in recently-published, high-resolution EM potential maps of the ribosome and β-galactosidase. Comparisons of simulated maps of these same groups with their experimental counterparts highlight the impact that charge has on the appearance of electric potential maps. © 2016 The Protein Society.

  18. Transmission electron microscopic characterization of hypersensitive human radicular dentin

    SciTech Connect

    Yoshiyama, M.; Noiri, Y.; Ozaki, K.; Uchida, A.; Ishikawa, Y.; Ishida, H. )

    1990-06-01

    Transmission electron microscopy (TEM) and x-ray microanalysis (XMA) were used for the study of the ultrastructure of the lumens of dentinal tubules in superficial layers of dentin specimens obtained by use of a new biopsy technique from both hypersensitive and naturally desensitized areas of exposed root surfaces, in vivo. The TEM images showed clearly that the lumens of most of the tubules were occluded with mineral crystals in naturally desensitized areas, but such lumens were empty and surrounded with peritubular and intertubular dentin in hypersensitive areas. Moreover, electron-dense structures that lined peritubular dentin were observed in the empty lumens of dentinal tubules.

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

    PubMed

    Navarro, G; Mateos, M; Navarro, J L; Canalda, C

    1991-01-01

    Forty stainless steel endodontic files were observed at scanning electron microscopy after being subjected to ten disinfection cycles of 10 minutes each one, immersed in different chemical disinfectants. Corrosion was not observed on the surface of the files in circumstances that this study was made.

  20. Architecture of dermatophyte cell Walls: Electron microscopic and biochemical analysis

    NASA Technical Reports Server (NTRS)

    Nozawa, Y.; Kitajima, Y.

    1984-01-01

    A review with 83 references on the cell wall structure of dermatophytes is presented. Topics discussed include separation and preparation of cell walls; microstructure of cell walls by electron microscopy; chemical composition of cell walls; structural model of cell walls; and morphological structure of cell walls.

  1. Hair morphology in androgenetic alopecia: sonographic and electron microscopic studies.

    PubMed

    Wortsman, Ximena; Guerrero, Robinson; Wortsman, Jacobo

    2014-07-01

    To assess hair morphology in androgenetic alopecia on sonography and electron microscopy. A prospective study was performed in 33 patients with androgenetic alopecia and 10 unaffected control participants. In vivo sonography of the hair follicles of the scalp and in vitro sonography and electron microscopy of the hair shafts were performed according to a standardized protocol that included analysis of the right frontal and occipital regions. The upper frequency limit of the ultrasound probes ranged between 15 and 18 MHz. Scalp hair follicles and hair shafts were recognizable on sonography in all cases. Hair follicles in alopecia cases had significantly lower depths (P < .05). The hair shafts in alopecia also had a different distribution of their laminar pattern on in vitro sonography, with a greater presence of mixed (trilaminar and bilaminar) and solely bilaminar tracts in comparison with the controls (mostly trilaminar). On electron microscopy, the alopecia hair tracts showed irregularities and commonly a "melted candle" appearance of the cuticle. Sonography and electron microscopy uncover distinct abnormalities in the morphology of hair in androgenetic alopecia, which may potentially support the diagnosis and management of this common condition. © 2014 by the American Institute of Ultrasound in Medicine.

  2. Electron-microscopic study of Sn-chrisotile asbestos nanocomposite

    NASA Astrophysics Data System (ADS)

    Sorokin, L. M.; Kalmykov, A. E.; Fokin, A. V.; Kumzerov, Yu. A.

    2014-04-01

    Transmission electron microscopy was used to study the structural state of tin in Sn-chrisotile asbestos nanocomposite. It is shown that tin in the nanocomposite forms a system of nanowires, which, in turn, consist of crystallites of different lengths. Various orientational relations between the matrix and crystallites are revealed.

  3. Novel low-dose imaging technique for characterizing atomic structures through scanning transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Su, Chia-Ping; Syu, Wei-Jhe; Hsiao, Chien-Nan; Lai, Ping-Shan; Chen, Chien-Chun

    2017-08-01

    To investigate dislocations or heterostructures across interfaces is now of great interest to condensed matter and materials scientists. With the advances in aberration-corrected electron optics, the scanning transmission electron microscope has demonstrated its excellent capability of characterizing atomic structures within nanomaterials, and well-resolved atomic-resolution images can be obtained through long-exposure data acquisition. However, the sample drifting, carbon contamination, and radiation damage hinder further analysis, such as deriving three-dimensional (3D) structures from a series of images. In this study, a method for obtaining atomic-resolution images with significantly reduced exposure time was developed, using which an original high-resolution image with approximately one tenth the electron dose can be obtained by combining a fast-scan high-magnification image and a slow-scan low-magnification image. The feasibility of obtaining 3D atomic structures using the proposed approach was demonstrated through multislice simulation. Finally, the feasibility and accuracy of image restoration were experimentally verified. This general method cannot only apply to electron microscopy but also benefit to image radiation-sensitive materials using various light sources.

  4. Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope.

    PubMed

    Hieckmann, Ellen; Nacke, Markus; Allardt, Matthias; Bodrov, Yury; Chekhonin, Paul; Skrotzki, Werner; Weber, Jörg

    2016-05-28

    Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared.

  5. Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope

    PubMed Central

    Hieckmann, Ellen; Nacke, Markus; Allardt, Matthias; Bodrov, Yury; Chekhonin, Paul; Skrotzki, Werner; Weber, Jörg

    2016-01-01

    Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared. PMID:27285177

  6. Histological and Electron Microscope Staining for the Identification of Elastic Fiber Networks.

    PubMed

    Davis, Elaine C; Li, Ling

    2017-01-01

    Elastic fibers are a major component of the extracellular matrix and are present in many tissues. Routine histology and standard electron microscopy procedures often do not allow for clear identification of elastic fibers making their organization and ultrastructure difficult to study. In this paper, we describe staining methods and procedures to enhance the contrast of elastin at both the light and electron microscope levels.

  7. Design of an electron microscope phase plate using a focused continuous-wave laser

    SciTech Connect

    Spence, J.; Muller, H; Jin, Jian; Danev, R; Padmore, H; Glaeser, R.M

    2010-07-01

    We propose a Zernike phase contrast electron microscope that uses an intense laser focus to convert a phase image into a visible image. We present the relativistic quantum theory of the phase shift caused by the laser–electron interaction, study resonant cavities for enhancing the laser intensity and discuss applications in biology, soft-materials science and atomic and molecular physics.

  8. Design of an electron microscope phase plate using a focused continuous-wave laser

    PubMed Central

    Müller, H; Jin, Jian; Danev, R; Spence, J; Padmore, H; Glaeser, R M

    2010-01-01

    We propose a Zernike phase contrast electron microscope that uses an intense laser focus to convert a phase image into a visible image. We present the relativistic quantum theory of the phase shift caused by the laser–electron interaction, study resonant cavities for enhancing the laser intensity and discuss applications in biology, soft-materials science and atomic and molecular physics. PMID:20808709

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  10. A transmission electron microscopic study of the Bethany iron meteorite

    NASA Astrophysics Data System (ADS)

    Hasan, F.; Axon, H. J.

    1985-02-01

    The Bethany iron meteorite, which is a part of the Gibeon shower, is a fine octahedrite with zoned plessite fields of various sizes. The optically irresolvable microstructural details inside the plessitic fields have been studied by transmission electron microscopy, and the crystallographic relationships between the primary kamacite (alpha) and the parent taenite (gamma), and between the alpha and gamma particles in the coarse plessite, have been examined using electron diffraction. In the case of primary kamacite, the orientation-relationship with gamma was close to the Nishiyama-Wasserman relationship, whereas, for the plessitic alpha, the orientation-relationship with gamma was close to Kurdjumov-Sachs. It was also found that the (111)-gamma and (110)-alpha planes were not strictly parallel. Additionally, measurements of the composition profile through the zoned plessite have been made using STEM microanalysis technique, and related to microstructure.

  11. Microscopic probabilistic model for the simulation of secondary electron emission

    SciTech Connect

    Furman, M.A.; Pivi, M.T.F.

    2002-07-29

    We provide a detailed description of a model and its computational algorithm for the secondary electron emission process. The model is based on a broad phenomenological fit to data for the secondary emission yield (SEY) and the emitted-energy spectrum. We provide two sets of values for the parameters by fitting our model to two particular data sets, one for copper and the other one for stainless steel.

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

    PubMed

    Tenora, F; Mituch, J; Hovorka, I

    1989-01-01

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

  13. Electron microscopic examination of wastewater biofilm formation and structural components.

    PubMed Central

    Eighmy, T T; Maratea, D; Bishop, P L

    1983-01-01

    This research documents in situ wastewater biofilm formation, structure, and physiochemical properties as revealed by scanning and transmission electron microscopy. Cationized ferritin was used to label anionic sites of the biofilm glycocalyx for viewing in thin section. Wastewater biofilm formation paralleled the processes involved in marine biofilm formation. Scanning electron microscopy revealed a dramatic increase in cell colonization and growth over a 144-h period. Constituents included a variety of actively dividing morphological types. Many of the colonizing bacteria were flagellated. Filaments were seen after primary colonization of the surface. Transmission electron microscopy revealed a dominant gram-negative cell wall structure in the biofilm constituents. At least three types of glycocalyces were observed. The predominant glycocalyx possessed interstices and was densely labeled with cationized ferritin. Two of the glycocalyces appeared to mediate biofilm adhesion to the substratum. The results suggest that the predominant glycocalyx of this thin wastewater biofilm serves, in part, to: (i) enclose the bacteria in a matrix and anchor the biofilm to the substratum and (ii) provide an extensive surface area with polyanionic properties. Images PMID:6881965

  14. Electron microscopic analysis of rotavirus assembly-replication intermediates

    SciTech Connect

    Boudreaux, Crystal E.; Kelly, Deborah F.; McDonald, Sarah M.

    2015-03-15

    Rotaviruses (RVs) replicate their segmented, double-stranded RNA genomes in tandem with early virion assembly. In this study, we sought to gain insight into the ultrastructure of RV assembly-replication intermediates (RIs) using transmission electron microscopy (EM). Specifically, we examined a replicase-competent, subcellular fraction that contains all known RV RIs. Three never-before-seen complexes were visualized in this fraction. Using in vitro reconstitution, we showed that ~15-nm doughnut-shaped proteins in strings were nonstructural protein 2 (NSP2) bound to viral RNA transcripts. Moreover, using immunoaffinity-capture EM, we revealed that ~20-nm pebble-shaped complexes contain the viral RNA polymerase (VP1) and RNA capping enzyme (VP3). Finally, using a gel purification method, we demonstrated that ~30–70-nm electron-dense, particle-shaped complexes represent replicase-competent core RIs, containing VP1, VP3, and NSP2 as well as capsid proteins VP2 and VP6. The results of this study raise new questions about the interactions among viral proteins and RNA during the concerted assembly–replicase process. - Highlights: • Rotaviruses replicate their genomes in tandem with early virion assembly. • Little is known about rotavirus assembly-replication intermediates. • Assembly-replication intermediates were imaged using electron microscopy.

  15. Electron beam detection of a Nanotube Scanning Force Microscope.

    PubMed

    Siria, Alessandro; Niguès, Antoine

    2017-09-14

    Atomic Force Microscopy (AFM) allows to probe matter at atomic scale by measuring the perturbation of a nanomechanical oscillator induced by near-field interaction forces. The quest to improve sensitivity and resolution of AFM forced the introduction of a new class of resonators with dimensions at the nanometer scale. In this context, nanotubes are the ultimate mechanical oscillators because of their one dimensional nature, small mass and almost perfect crystallinity. Coupled to the possibility of functionalisation, these properties make them the perfect candidates as ultra sensitive, on-demand force sensors. However their dimensions make the measurement of the mechanical properties a challenging task in particular when working in cavity free geometry at ambient temperature. By using a focused electron beam, we show that the mechanical response of nanotubes can be quantitatively measured while approaching to a surface sample. By coupling electron beam detection of individual nanotubes with a custom AFM we image the surface topography of a sample by continuously measuring the mechanical properties of the nanoresonators. The combination of very small size and mass together with the high resolution of the electron beam detection method offers unprecedented opportunities for the development of a new class of nanotube-based scanning force microscopy.

  16. An Electron Microscopic Study of the Intestinal Villus

    PubMed Central

    Palay, Sanford L.; Karlin, Leonard J.

    1959-01-01

    The structure of the intestinal villus of the rat was studied in thin sections of tissue fixed in buffered osmium tetroxide and embedded in methacrylate. The simple columnar epithelium investing the villus is surmounted by a striated border consisting of slender projections of the cell surface. These microvilli are arranged in almost crystalline, hexagonal array, and increase the apical surface area of the cell by a factor of 24. The core of each microvillus is filled with fine fibrils which arise from the filamentous substance of the terminal web underlying the striated border. Each microvillus is covered by a tubular extension of the plasma membrane of the epithelial cell. Pinocytotic vesicles originating from the plasma membrane occur at the bases of the intermicrovillous spaces. The nucleus, mitochondria, and the endoplasmic reticulum of the epithelial cell display no unusual features. Small bits of ergastoplasm occur in the apical cytoplasm. A thin basement membrane separates the epithelium from the lamina propria which consists of vessels, nerves, and numerous lymphocytes, eosinophiles, mast cells, plasma cells, smooth muscle fibers, and macrophages suspended in a delicate stroma of fibroblasts and collagen fibers. Intercellular fat droplets often occur in this stroma, even in animals fasted for 40 hours. The blood capillaries are distinguished by their extremely attenuated, fenestrated endothelial cells. The lacteal has a thicker endothelium which, although not fenestrated, appears to have significant interruptions, especially at the margins between neighboring lining cells. Strands of smooth muscle always accompany the lacteal but do not form an integral part of its wall. Unmyelinated nerves, many of which are too small to be distinguished with the light microscope, course through the lamina propria in association with the vessels. The nerve fibers evidently do not cross the basement membrane into the epithelium. Neuromuscular junctions or other terminal

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

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  18. Transmission electron microscopic study of polytene chromosome 2R from Drosophila melanogaster.

    PubMed

    Wu, M; Waddell, J

    1982-01-01

    A simple and rapid method for studying polytene chromosome squashes by transmission electron microscope (TEM) is described. This technique provides close correlation between the light microscopic image and the TEM image. Fine structures of the chromosomes are preserved. The band pattern of region 44 A to 50 F of the chromosome 2 R has been analyzed and compared with Bridges' map (1935) and Lefevre's photographic representation (1976).

  19. Charge contrast imaging of biomaterials in a variable pressure scanning electron microscope.

    PubMed

    Clode, Peta L

    2006-09-01

    Charge contrast imaging (CCI) is a dynamic phenomenon recently reported in insulating and semiconducting materials imaged with low vacuum or variable pressure scanning electron microscopes (SEM). Data presented in this paper illustrates that CCI can also be applied to biominerals and biological soft-tissues and that useful and unique structural information can be obtained from routine samples. Various resin-embedded samples were considered and example images from several different biomaterials are presented. Due to the diverse nature of samples that appear to exhibit charge contrast, this imaging technique has prospective application in a wide range of biological and biomedical research. This work represents the first application of CCI to biomaterials and in particular, highlights a new method for investigating the formation, structure and growth of biominerals.

  20. Tilting and moving-object lens for a 3D electron microscope.

    PubMed

    Ura, Katsumi

    2016-10-01

    I investigated the tilting and movement of the objective lens of a 3D electron microscope electrically as an extension of the moving-objective lens concept. The electric or magnetic potential along the tilted optical axis is analytically expressed by a multipole potential expansion about the fixed central axis. The field distributions for axially symmetric dipole and quadrupole components are numerically shown, where the optical axis of a bell-shaped magnetic lens is tilted around the lens center by up to 60°. The hexapole and octapole components are also shown at a tilt angle of 45°. © The Author 2016. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

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

    PubMed Central

    Pourlis, Aris F.

    2013-01-01

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

  2. Electron microscopic time-lapse visualization of surface pore filtration on particulate matter trapping process.

    PubMed

    Sanui, Ryoko; Hanamura, Katsunori

    2016-09-01

    A scanning electron microscope (SEM) was used to dynamically visualize the particulate matter (PM) trapping process on diesel particulate filter (DPF) walls at a micro scale as 'time-lapse' images corresponding to the increase in pressure drop simultaneously measured through the DPF. This visualization and pressure drop measurement led to the conclusion that the PM trapping in surface pores was driven by PM bridging and stacking at constricted areas in porous channels. This caused a drastic increase in the pressure drop during PM accumulation at the beginning of the PM trapping process. The relationship between the porous structure of the DPF and the depth of the surface pore was investigated in terms of the porosity distribution and PM penetration depth near the wall surface with respect to depth. The pressure drop calculated with an assumed surface pore depth showed a good correspondence to the measured pressure drop.

  3. Horner's syndrome: an electron microscopic study of a human iris.

    PubMed Central

    McCartney, A. C.; Riordan-Eva, P.; Howes, R. C.; Spalton, D. J.

    1992-01-01

    Electron microscopy was performed on the irides of a man with a history of a long standing Horner's syndrome which resulted in iris heterochromia. Comparison of his normal brown iris with the depigmented blue iris showed depletion of anterior border cells and absence of sympathetic nerve fibres. Stromal melanocyte numbers were also diminished but melanosome numbers within the residual cells were not significantly different. Postnatal maintenance of stromal and anterior border zone pigmentation, derived from the neural crest, would appear to be dependent on an intact sympathetic nerve supply in contrast to the iris pigment epithelium which remains normally unaffected in Horner's syndrome. Images PMID:1486079

  4. [Electron microscopic study of pathogenic bacteria on environmental objects].

    PubMed

    Pavlova, I B; Lenchenko, E M

    1998-01-01

    The morphological picture of different bacteria (Salmonella typhimurium, Proteus vulgaris, Klebsiella pneumoniae, Pseudomonas aeruginosa, Yersinia enterocolitica O3, Y.pseudotuberculosis 1, Y.frederiksenii, Y.intermedia, Y.kristensenii) on environmental objects was studied with the use of scanning electron microscopy (SEM). Bacteria adhered to the surface of pieces of fodder, egg shell, cabbage leaves and form microcolonies, whose morphology was similar to colonies, grown on nutrient media. The cells produced extracellular substances, seen in SEM as integuments. These integuments were gourd to protect the population from the action of unfavorable factors.

  5. Continual skin peeling syndrome. An electron microscopic study.

    PubMed

    Silverman, A K; Ellis, C N; Beals, T F; Woo, T Y

    1986-01-01

    We encountered a patient with continual skin peeling syndrome, a rare disorder in which generalized, noninflammatory exfoliation of the stratum corneum occurs. Although scaling occurred spontaneously in our patient, he was also able to manually peel sheets of skin without bleeding or pain. Histologically, there was separation of corneocytes above the granular cell layer. Ultrastructural examination revealed an unusual type of intracellular cleavage, in which the plasma membrane of the "peeling" cell remained firmly adherent to the underlying cell while the upper part of the cell exfoliated. Unique intercellular electron-dense globular deposits were localized to the stratum corneum.

  6. Microscopic Investigation of Martian Soil Samples at the Phoenix Site

    NASA Astrophysics Data System (ADS)

    Pike, W. T.; Staufer, U.; Hecht, M. H.; Marshall, J.; Team, M. M.

    2008-12-01

    We have used the optical and atomic force microscopes (OM and AFM) of the MECA microscopy station on Phoenix (M. Hecht et al., Microscopy Capabilities of the Microscopy, Electrochemistry, and Conductivity Analyzer , JGR accepted for publication) to image samples within reach of the robot arm and delivered to sets of substrates mounted in a sample wheel. For loading the sample, the wheel was pushed out of the MECA enclosure, exposing only one set of substrates: strong and weak magnets, micro-buckets, silicone and silicon featuring grids of micromachined small holes and posts to capture particles. A thickness of up to 200 micrometers of material can be brought into the microscopy station under a leveling blade before the samples are rotated into the field of view of the microscopes as the substrates are tilted from horizontal to vertical. This tilt can cause the loss of a portion of the material depending on the relative strength of the adhesion forces compared to Martian gravity. The time constraints of sample delivery have so far ensured that any ice would have sublimed prior to delivery. From OM images of fully loaded substrates the particles found so far can be very coarsely grouped into three different categories: 1. subrounded strongly magnetic grains, of both a rough and glassy appearance with different shades of yellow, red, brown and black color in a size range of 50 to 100 micrometers, comprising about 10% of the sample volume; 2. small white flecks of a few micrometers in size, about 0.5% of the sample volume; 3. a majority component of a fine, uniformly coloured orange-reddish dust forming agglomerations from a few tens of microns in diameter to below the resolution of the OM with less magnetic attraction than the larger grains. Using populations on more sparsely populated substrates a size distribution could be estimated. The particle size distribution increases with decreasing size until cut off by the 4-micrometer resolution limit of the OM. The AFM

  7. Structural Fingerprinting of Nanocrystals in the Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Moeck, Peter

    2008-05-01

    Two novel strategies for the structurally identification of nanocrystals [1] from either a high resolution (HR) transmission electron microscopy (TEM) image or a precession electron diffractogram (PED) [2] are described (and demonstrated on a mixture of nanocrystalline maghemite and magnetite [3]). The structural information that can be extracted from a HRTEM image is the projected reciprocal lattice geometry, the plane symmetry group, a few structure factor amplitudes and phases. Except for the structure factor phases, the same kind of information can be extracted from a PED, but the information that can be used for structural fingerprinting is in this case not limited to the resolution of the TEM. Searching for this kind of information in (open access) databases (e.g. [4]) and matching it with high figures of merit to that of candidate structures allows for highly discriminatory identifications of nanocrystals. [1] P. Moeck, P. Fraundorf, Z. f"ur Kristallogr. 222 (2007) 634-645; open-access issue at http://www.atypon-link.com/OLD/doi/pdf/10.1524/zkri.2007.222.11.634; expanded version at arXiv:0706.2021 [2] http://www.nanomegas.com [3] P. Moeck, arXiv:0804.0063 [4] http://nanocrystallography.research.pdx.edu/CIF-searchable

  8. HIGH-RESOLUTION ELECTRON MICROSCOPIC ANALYSIS OF THE AMYLOID FIBRIL

    PubMed Central

    Shirahama, Tsuranobu; Cohen, Alan S.

    1967-01-01

    The ultrastructural organization of the fibrous component of amyloid has been analyzed by means of high resolution electron microscopy of negatively stained isolated amyloid fibrils and of positively stained amyloid fibrils in thin tissue sections. It was found that a number of subunits could be resolved according to their dimensions. The following structural organization is proposed. The amyloid fibril, the fibrous component of amyloid as seen in electron microscopy of thin tissue sections, consists of a number of filaments aggregated side-by-side. These amyloid filaments are approximately 75–80 A in diameter and consist of five (or less likely six) subunits (amyloid protofibrils) which are arranged parallel to each other, longitudinal or slightly oblique to the long axis of the filament. The filament has often seemed to disperse into several longitudinal rows. The amyloid protofibril is about 25–35 A wide and appears to consist of two or three subunit strands helically arranged with a 35–50-A repeat (or, less likely, is composed of globular subunits aggregated end-to-end). These amyloid subprotofibrillar strands measure approximately 10–15 A in diameter. PMID:6036530

  9. Electron microscopic analysis of rotavirus assembly-replication intermediates

    PubMed Central

    Boudreaux, Crystal E.; Kelly, Deborah F.; McDonald, Sarah M.

    2015-01-01

    Rotaviruses (RVs) replicate their segmented, double-stranded RNA genomes in tandem with early virion assembly. In this study, we sought to gain insight into the ultrastructure of RV assembly-replication intermediates (RIs) using transmission electron microscopy (EM). Specifically, we examined a replicase-competent, subcellular fraction that contains all known RV RIs. Three never-before-seen complexes were visualized in this fraction. Using in vitro reconstitution, we showed that ~15-nm doughnut-shaped proteins in strings were nonstructural protein 2 (NSP2) bound to viral RNA transcripts. Moreover, using immunoaffinity-capture EM, we revealed that ~20-nm pebble-shaped complexes contain the viral RNA polymerase (VP1) and RNA capping enzyme (VP3). Finally, using a gel purification method, we demonstrated that ~30–70-nm electron-dense, particle-shaped complexes represent replicase-competent core RIs, containing VP1, VP3, and NSP2 as well as capsid proteins VP2 and VP6. The results of this study raise new questions about the interactions among viral proteins and RNA during the concerted assembly-replicase process. PMID:25635339

  10. Prevention of electron beam transmittance for biological cell imaging using electron beam excitation-assisted optical microscope

    NASA Astrophysics Data System (ADS)

    Fukuta, Masahiro; Nawa, Yasunori; Inami, Wataru; Kawata, Yoshimasa

    2016-12-01

    We demonstrated the high-spatial-resolution imaging of label-free biological cells using an electron beam excitation-assisted optical (EXA) microscope without irradiation damage by the electron beam. An EXA microscope can be used to observe a specimen with a nanometric light source excited in the Si3N4 membrane by an electron beam. The incident electron beam penetrates the Si3N4 membrane and damages the specimen. To suppress the irradiation damage of the specimen, we prevented the transmittance of the electron beam by coating the Si3N4 membrane with a gold thin film. To obtain an electron beam transmittance through the Si3N4 of 0%, a gold film of 15 nm thickness was required. By adding the gold layer, a label-free cellular structure was observed with 135-nm spatial resolution.

  11. Prevention of electron beam transmittance for biological cell imaging using electron beam excitation-assisted optical microscope

    NASA Astrophysics Data System (ADS)

    Fukuta, Masahiro; Nawa, Yasunori; Inami, Wataru; Kawata, Yoshimasa

    2017-04-01

    We demonstrated the high-spatial-resolution imaging of label-free biological cells using an electron beam excitation-assisted optical (EXA) microscope without irradiation damage by the electron beam. An EXA microscope can be used to observe a specimen with a nanometric light source excited in the Si3N4 membrane by an electron beam. The incident electron beam penetrates the Si3N4 membrane and damages the specimen. To suppress the irradiation damage of the specimen, we prevented the transmittance of the electron beam by coating the Si3N4 membrane with a gold thin film. To obtain an electron beam transmittance through the Si3N4 of 0%, a gold film of 15 nm thickness was required. By adding the gold layer, a label-free cellular structure was observed with 135-nm spatial resolution.

  12. Influence of cathode geometry on electron dynamics in an ultrafast electron microscope.

    PubMed

    Ji, Shaozheng; Piazza, Luca; Cao, Gaolong; Park, Sang Tae; Reed, Bryan W; Masiel, Daniel J; Weissenrieder, Jonas

    2017-09-01

    Efforts to understand matter at ever-increasing spatial and temporal resolutions have led to the development of instruments such as the ultrafast transmission electron microscope (UEM) that can capture transient processes with combined nanometer and picosecond resolutions. However, analysis by UEM is often associated with extended acquisition times, mainly due to the limitations of the electron gun. Improvements are hampered by tradeoffs in realizing combinations of the conflicting objectives for source size, emittance, and energy and temporal dispersion. Fundamentally, the performance of the gun is a function of the cathode material, the gun and cathode geometry, and the local fields. Especially shank emission from a truncated tip cathode results in severe broadening effects and therefore such electrons must be filtered by applying a Wehnelt bias. Here we study the influence of the cathode geometry and the Wehnelt bias on the performance of a photoelectron gun in a thermionic configuration. We combine experimental analysis with finite element simulations tracing the paths of individual photoelectrons in the relevant 3D geometry. Specifically, we compare the performance of guard ring cathodes with no shank emission to conventional truncated tip geometries. We find that a guard ring cathode allows operation at minimum Wehnelt bias and improve the temporal resolution under realistic operation conditions in an UEM. At low bias, the Wehnelt exhibits stronger focus for guard ring than truncated tip cathodes. The increase in temporal spread with bias is mainly a result from a decrease in the accelerating field near the cathode surface. Furthermore, simulations reveal that the temporal dispersion is also influenced by the intrinsic angular distribution in the photoemission process and the initial energy spread. However, a smaller emission spot on the cathode is not a dominant driver for enhancing time resolution. Space charge induced temporal broadening shows a close to

  13. Influence of cathode geometry on electron dynamics in an ultrafast electron microscope

    PubMed Central

    Ji, Shaozheng; Piazza, Luca; Cao, Gaolong; Park, Sang Tae; Reed, Bryan W.; Masiel, Daniel J.; Weissenrieder, Jonas

    2017-01-01

    Efforts to understand matter at ever-increasing spatial and temporal resolutions have led to the development of instruments such as the ultrafast transmission electron microscope (UEM) that can capture transient processes with combined nanometer and picosecond resolutions. However, analysis by UEM is often associated with extended acquisition times, mainly due to the limitations of the electron gun. Improvements are hampered by tradeoffs in realizing combinations of the conflicting objectives for source size, emittance, and energy and temporal dispersion. Fundamentally, the performance of the gun is a function of the cathode material, the gun and cathode geometry, and the local fields. Especially shank emission from a truncated tip cathode results in severe broadening effects and therefore such electrons must be filtered by applying a Wehnelt bias. Here we study the influence of the cathode geometry and the Wehnelt bias on the performance of a photoelectron gun in a thermionic configuration. We combine experimental analysis with finite element simulations tracing the paths of individual photoelectrons in the relevant 3D geometry. Specifically, we compare the performance of guard ring cathodes with no shank emission to conventional truncated tip geometries. We find that a guard ring cathode allows operation at minimum Wehnelt bias and improve the temporal resolution under realistic operation conditions in an UEM. At low bias, the Wehnelt exhibits stronger focus for guard ring than truncated tip cathodes. The increase in temporal spread with bias is mainly a result from a decrease in the accelerating field near the cathode surface. Furthermore, simulations reveal that the temporal dispersion is also influenced by the intrinsic angular distribution in the photoemission process and the initial energy spread. However, a smaller emission spot on the cathode is not a dominant driver for enhancing time resolution. Space charge induced temporal broadening shows a close to

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

    NASA Astrophysics Data System (ADS)

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

    2002-10-01

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

  15. [Electron microscopic studies in enzootic muscular dystrophy in cattle].

    PubMed

    Bergmann, V; Kursa, J

    1979-01-01

    Electron microscopy was used to examine the sekeletal muscles of young cattle, aged between 13 and 24 months, with spontaneous enzootic myodystrophy (nutritional myodegeneration due to selenium deficiency, white muscle disease). The animals had been received from Sumava District, Southern Bohemia, an area known for shortage of selenium. Outbreaks of clinical illness were recorded from them between four and 18 days from the beginning of grazing. Most of the ultrastructural changes included decomposition of myofibrils and hyalinisation of fibres as well as defective fibril synthesis (Z-striation abnormality), some of the latter phenomena recordable even from regenerating fibre. However, minor disorders only were established from the mitochondria, sarcoplasmic reticulum, components of sarcoplasm, and vessels. There were far-reaching ultrastructural similarities to nutritional myodegeneration of sheep. The changes recorded are likely to suggest a specific role played by selenium in the formation and preservation of myofibril proteins.

  16. Transmission electron microscope cells for use with liquid samples

    DOEpatents

    Khalid, Waqas; Alivisatos, Paul A.; Zettl, Alexander K.

    2016-08-09

    This disclosure provides systems, methods, and devices related to transmission electron microscopy cells for use with liquids. In one aspect a device includes a substrate, a first graphene layer, and a second graphene layer. The substrate has a first surface and a second surface. The first surface defines a first channel, a second channel, and an outlet channel. The first channel and the second channel are joined to the outlet channel. The outlet channel defines a viewport region forming a though hole in the substrate. The first graphene layer overlays the first surface of the substrate, including an interior area of the first channel, the second channel, and the outlet channel. The second graphene layer overlays the first surface of the substrate, including open regions defined by the first channel, the second channel, and the outlet channel.

  17. Measurement of boundary plane inclination in a scanning electron microscope

    SciTech Connect

    Randle, V.; Dingley, D. )

    1989-09-01

    Recently, a method has been devised for measuring the boundary orientations using backscattered Kikuchi diffraction (BKD, otherwise known as electron backscattering, EBS). The work reported demonstrates that BKD can be efficiently used to measure both the misorientation across grain boundaries and also the orientation of boundary planes. In nickel it has been shown that the boundaries of grains which are situated along the corner of a rectangular specimen rotate so as to minimize their interfacial energy. For non-coincidence site lattices related grains, boundaries tend to align normal to the edge of the specimen, while {Sigma} = 3 and {Sigma} = 9 CSLs tend to rotate to tilt configuration, particularly asymmetric tilts such as {l brace}111{r brace}/ {l brace}115{r brace} or {l brace}110{r brace}/{l brace}114{r brace}.

  18. Using electron microscopes to look into the lung.

    PubMed

    Ochs, Matthias; Knudsen, Lars; Hegermann, Jan; Wrede, Christoph; Grothausmann, Roman; Mühlfeld, Christian

    2016-12-01

    In the nineteenth century, there was a dispute about the existence of a lung alveolar epithelium which remained unsolved until the invention of electron microscopy (EM) and its application to the lung. From the early 1960s, Ewald Weibel became the master of lung EM. He showed that the alveolar epithelium is covered with a lining layer containing surfactant. Weibel also explained the phenomenon of "non-nucleated plates" observed already in 1881 by Albert Kölliker. Weibel's most significant contribution was to the development of stereological methods. Therefore, quantitative characterization of lung structure revealing structure-function relationships became possible. Today, the spectrum of EM methods to study the fine structure of the lung has been extended significantly. Cryo-preparation techniques are available which are necessary for immunogold labeling of molecules. Energy-filtering techniques can be used for the detection of elements. There have also been major improvements in stereology, thus providing a very versatile toolbox for quantitative lung phenotype analyses. A new dimension was added by 3D EM techniques. Depending on the desired sample size and resolution, the spectrum ranges from array tomography via serial block face scanning EM and focused ion beam scanning EM to electron tomography. These 3D datasets provide new insights into lung ultrastructure. Biomedical EM is an ever-developing field. Its high resolution remains unparalleled. Moreover, EM has the unique advantage of providing an "open view" into cells and tissues within their full architectural context. Therefore, EM will remain an indispensable tool for a better understanding of the lung's functional design.

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

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

    PubMed

    Jones, L; Nellist, P D

    2014-05-01

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

  1. Intercomparison of lateral scales of scanning electron microscopes and atomic force microscopes in research institutes in Northern Europe

    NASA Astrophysics Data System (ADS)

    Seppä, Jeremias; Korpelainen, Virpi; Bergstrand, Sten; Karlsson, Helge; Lillepea, Lauri; Lassila, Antti

    2014-04-01

    An intercomparison of lateral scales of scanning electron microscopes (SEM) and atomic force microscopes (AFM) in various research laboratories in Northern Europe was organized by the local national metrology institutes. In this paper are presented the results of the comparison, with also an example uncertainty budget for AFM grating pitch measurement. Grating samples (1D) were circulated among the participating laboratories. The participating laboratories were also asked about the calibration of their instruments. The accuracy of the uncertainty estimates seemed to vary largely between the laboratories, and for some laboratories the appropriateness of the calibration procedures could be considered. Several institutes (60% of all results in terms of En value) also had good comprehension of their measurement capability. The average difference from reference value was 6.7 and 10.0 nm for calibrated instruments and 20.6 and 39.9 nm for uncalibrated instruments for 300 nm and 700 nm gratings, respectively. The correlation of the results for both nominally 300 and 700 nm gratings shows that a simple scale factor calibration would have corrected a large part of the deviations from the reference values.

  2. Sub-Angstrom Low Voltage Performance of a Monochromated, Aberration-Corrected Transmission Electron Microscope

    PubMed Central

    Bell, David C.; Russo, Christopher J.; Benner, Gerd

    2011-01-01

    Lowering the electron energy in the transmission electron microscope allows for a significant improvement in contrast of light elements, and reduces knock-on damage for most materials. If low-voltage electron microscopes are defined as those with accelerating voltages below 100 kV, the introduction of aberration correctors and monochromators to the electron microscope column enables Ångstrom-level resolution, which was previously reserved for higher voltage instruments. Decreasing electron energy has three important advantages: 1) knock-on damage is lower, which is critically important for sensitive materials such as graphene and carbon nanotubes; 2) cross sections for electron-energy-loss spectroscopy increase, improving signal-to-noise for chemical analysis; 3) elastic scattering cross sections increase, improving contrast in high-resolution, zero-loss images. The results presented indicate that decreasing the acceleration voltage from 200 kV to 80 kV in a monochromated, aberration-corrected microscope enhances the contrast while retaining sub-angstrom resolution. These improvements in low-voltage performance are expected to produce many new results and enable a wealth of new experiments in materials science. PMID:20598206

  3. Nanoscale imaging of whole cells using a liquid enclosure and a scanning transmission electron microscope.

    PubMed

    Peckys, Diana B; Veith, Gabriel M; Joy, David C; de Jonge, Niels

    2009-12-14

    Nanoscale imaging techniques are needed to investigate cellular function at the level of individual proteins and to study the interaction of nanomaterials with biological systems. We imaged whole fixed cells in liquid state with a scanning transmission electron microscope (STEM) using a micrometer-sized liquid enclosure with electron transparent windows providing a wet specimen environment. Wet-STEM images were obtained of fixed E. coli bacteria labeled with gold nanoparticles attached to surface membrane proteins. Mammalian cells (COS7) were incubated with gold-tagged epidermal growth factor and fixed. STEM imaging of these cells resulted in a resolution of 3 nm for the gold nanoparticles. The wet-STEM method has several advantages over conventional imaging techniques. Most important is the capability to image whole fixed cells in a wet environment with nanometer resolution, which can be used, e.g., to map individual protein distributions in/on whole cells. The sample preparation is compatible with that used for fluorescent microscopy on fixed cells for experiments involving nanoparticles. Thirdly, the system is rather simple and involves only minimal new equipment in an electron microscopy (EM) laboratory.

  4. Imaging flux vortices in type II superconductors with a commercial transmission electron microscope.

    PubMed

    Loudon, J C; Midgley, P A

    2009-05-01

    Flux vortices in superconductors can be imaged using transmission electron microscopy because the electron beam is deflected by the magnetic flux associated with the vortices. This technique has a better spatial and temporal resolution than many other imaging techniques and is sensitive to the magnetic flux density within each vortex, not simply the fields at the sample surface. Despite these advantages, only two groups have successfully employed the technique using specially adapted instruments. Here we demonstrate that vortices can be imaged with a modern, commercial transmission electron microscope operating at 300kV equipped with a field emission gun, Lorentz lens and a liquid helium cooled sample holder. We introduce superconductivity for non-specialists and discuss techniques for simulating and optimising images of flux vortices. Sample preparation is discussed in detail as the main difficulty with the technique is the requirement for samples with very large (>10microm), flat areas so that the image is not dominated by diffraction contrast. We have imaged vortices in superconducting Bi(2)Sr(2)CaCu(2)O(8-delta) and use correlation functions to investigate the ordered arrangements they adopt as a function of applied magnetic field.

  5. Nanoscale Imaging of Whole Cells Using a Liquid Enclosure and a Scanning Transmission Electron Microscope

    PubMed Central

    Peckys, Diana B.; Veith, Gabriel M.; Joy, David C.; de Jonge, Niels

    2009-01-01

    Nanoscale imaging techniques are needed to investigate cellular function at the level of individual proteins and to study the interaction of nanomaterials with biological systems. We imaged whole fixed cells in liquid state with a scanning transmission electron microscope (STEM) using a micrometer-sized liquid enclosure with electron transparent windows providing a wet specimen environment. Wet-STEM images were obtained of fixed E. coli bacteria labeled with gold nanoparticles attached to surface membrane proteins. Mammalian cells (COS7) were incubated with gold-tagged epidermal growth factor and fixed. STEM imaging of these cells resulted in a resolution of 3 nm for the gold nanoparticles. The wet-STEM method has several advantages over conventional imaging techniques. Most important is the capability to image whole fixed cells in a wet environment with nanometer resolution, which can be used, e.g., to map individual protein distributions in/on whole cells. The sample preparation is compatible with that used for fluorescent microscopy on fixed cells for experiments involving nanoparticles. Thirdly, the system is rather simple and involves only minimal new equipment in an electron microscopy (EM) laboratory. PMID:20020038

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

    PubMed

    Wight, S A; Zeissler, C J

    1993-08-01

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

  7. Removal of Vesicle Structures From Transmission Electron Microscope Images

    PubMed Central

    Jensen, Katrine Hommelhoff; Sigworth, Fred J.; Brandt, Sami Sebastian

    2016-01-01

    In this paper, we address the problem of imaging membrane proteins for single-particle cryo-electron microscopy reconstruction of the isolated protein structure. More precisely, we propose a method for learning and removing the interfering vesicle signals from the micrograph, prior to reconstruction. In our approach, we estimate the subspace of the vesicle structures and project the micrographs onto the orthogonal complement of this subspace. We construct a 2d statistical model of the vesicle structure, based on higher order singular value decomposition (HOSVD), by considering the structural symmetries of the vesicles in the polar coordinate plane. We then propose to lift the HOSVD model to a novel hierarchical model by summarizing the multidimensional HOSVD coefficients by their principal components. Along with the model, a solid vesicle normalization scheme and model selection criterion are proposed to make a compact and general model. The results show that the vesicle structures are accurately separated from the background by the HOSVD model that is also able to adapt to the asymmetries of the vesicles. This is a promising result and suggests even wider applicability of the proposed approach in learning and removal of statistical structures. PMID:26642456

  8. Electron Microscopic Visualization of Protein Assemblies on Flattened DNA Origami.

    PubMed

    Mallik, Leena; Dhakal, Soma; Nichols, Joseph; Mahoney, Jacob; Dosey, Anne M; Jiang, Shuoxing; Sunahara, Roger K; Skiniotis, Georgios; Walter, Nils G

    2015-07-28

    DNA provides an ideal substrate for the engineering of versatile nanostructures due to its reliable Watson-Crick base pairing and well-characterized conformation. One of the most promising applications of DNA nanostructures arises from the site-directed spatial arrangement with nanometer precision of guest components such as proteins, metal nanoparticles, and small molecules. Two-dimensional DNA origami architectures, in particular, offer a simple design, high yield of assembly, and large surface area for use as a nanoplatform. However, such single-layer DNA origami were recently found to be structurally polymorphous due to their high flexibility, leading to the development of conformationally restrained multilayered origami that lack some of the advantages of the single-layer designs. Here we monitored single-layer DNA origami by transmission electron microscopy (EM) and discovered that their conformational heterogeneity is dramatically reduced in the presence of a low concentration of dimethyl sulfoxide, allowing for an efficient flattening onto the carbon support of an EM grid. We further demonstrated that streptavidin and a biotinylated target protein (cocaine esterase, CocE) can be captured at predesignated sites on these flattened origami while maintaining their functional integrity. Our demonstration that protein assemblies can be constructed with high spatial precision (within ∼2 nm of their predicted position on the platforms) by using strategically flattened single-layer origami paves the way for exploiting well-defined guest molecule assemblies for biochemistry and nanotechnology applications.

  9. Nanomaterial engineering and property studies in a transmission electron microscope.

    PubMed

    Golberg, Dmitri; Costa, Pedro M F J; Wang, Ming-Sheng; Wei, Xianlong; Tang, Dai-Ming; Xu, Zhi; Huang, Yang; Gautam, Ujjal K; Liu, Baodan; Zeng, Haibo; Kawamoto, Naoyki; Zhi, Chunyi; Mitome, Masanori; Bando, Yoshio

    2012-01-10

    Modern methods of in situ transmission electron microscopy (TEM) allow one to not only manipulate with a nanoscale object at the nanometer-range precision but also to get deep insights into its physical and chemical statuses. Dedicated TEM holders combining the capabilities of a conventional high-resolution TEM instrument and atomic force -, and/or scanning tunneling microscopy probes become the powerful tools in nanomaterials analysis. This progress report highlights the past, present and future of these exciting methods based on the extensive authors endeavors over the last five years. The objects of interest are diverse. They include carbon, boron nitride and other inorganic one- and two-dimensional nanoscale materials, e.g., nanotubes, nanowires and nanosheets. The key point of all experiments discussed is that the mechanical and electrical transport data are acquired on an individual nanostructure level under ultimately high spatial, temporal and energy resolution achievable in TEM, and thus can directly be linked to morphological, structural and chemical peculiarities of a given nanomaterial. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Ion and electron beam nanofabrication of the which-way double-slit experiment in a transmission electron microscope

    SciTech Connect

    Frabboni, Stefano

    2010-12-27

    We have realized a which-way experiment closely resembling the original Feynman's proposal exploiting focused ion beam milling to prepare two nanoslits and electron beam induced deposition to grow, selectively over one of them, electron transparent layers of low atomic number amorphous material to realize a which-way detector for high energy electrons. By carrying out the experiment in an electron microscope equipped with an energy filter, we show that the inelastic scattering of electron transmitted through amorphous layers of different thicknesses provides the control of the dissipative interaction process responsible for the localization phenomena which cancels out the interference effects.

  11. Quantitative Nanostructure Characterization Using Atomic Pair Distribution Functions Obtained From Laboratory Electron Microscopes

    SciTech Connect

    Abeykoon M.; Billinge S.; Malliakas, C.D.; Juhas, P.; Bozin, E.S.; Kanatzidis, M.G.

    2012-05-01

    Quantitatively reliable atomic pair distribution functions (PDFs) have been obtained from nanomaterials in a straightforward way from a standard laboratory transmission electron microscope (TEM). The approach looks very promising for making electron derived PDFs (ePDFs) a routine step in the characterization of nanomaterials because of the ubiquity of such TEMs in chemistry and materials laboratories. No special attachments such as energy filters were required on the microscope. The methodology for obtaining the ePDFs is described as well as some opportunities and limitations of the method.

  12. AN ELECTRON MICROSCOPE STUDY OF CULTURED RAT SPINAL CORD

    PubMed Central

    Bunge, Richard P.; Bunge, Mary Bartlett; Peterson, Edith R.

    1965-01-01

    Explants prepared from 17- to 18-day fetal rat spinal cord were allowed to mature in culture; such preparations have been shown to differentiate and myelinate in vitro (61) and to be capable of complex bioelectric activity (14–16). At 23, 35, or 76 days, the cultures were fixed (without removal from the coverslip) in buffered OsO4, embedded in Epon, sectioned, and stained for light and electron microscopy. These mature explants generally are composed of several strata of neurons with an overlying zone of neuropil. The remarkable cytological similarity between in vivo and in vitro nervous tissues is established by the following observations. Cells and processes in the central culture mass are generally closely packed together with little intervening space. Neurons exhibit well developed Nissl bodies, elaborate Golgi regions, and subsurface cisternae. Axosomatic and axodendritic synapses, including synaptic junctions between axons and dendritic spines, are present. Typical synaptic vesicles and increased membrane densities are seen at the terminals. Variations in synaptic fine structure (Type 1 and Type 2 synapses of Gray) are visible. Some characteristics of the cultured spinal cord resemble infrequently observed specializations of in vivo central nervous tissue. Neuronal somas may display minute synapse-bearing projections. Occasionally, synaptic vesicles are grouped in a crystal-like array. A variety of glial cells, many apparently at intermediate stages of differentiation, are found throughout the otherwise mature explant. There is ultrastructural evidence of extensive glycogen deposits in some glial processes and scattered glycogen particles in neuronal terminals. This is the first description of the ultrastructure of cultured spinal cord. Where possible, correlation is made between the ultrastructural data and the known physiological properties of these cultures. PMID:14326105

  13. Choice of operating voltage for a transmission electron microscope.

    PubMed

    Egerton, R F

    2014-10-01

    An accelerating voltage of 100-300kV remains a good choice for the majority of TEM or STEM specimens, avoiding the expense of high-voltage microscopy but providing the possibility of atomic resolution even in the absence of lens-aberration correction. For specimens thicker than a few tens of nm, the image intensity and scattering contrast are likely to be higher than at lower voltage, as is the visibility of ionization edges below 1000eV (as required for EELS elemental analysis). In thick (>100nm) specimens, higher voltage ensures less beam broadening and better spatial resolution for STEM imaging and EDX spectroscopy. Low-voltage (e.g. 30kV) TEM or STEM is attractive for a very thin (e.g. 10nm) specimen, as it provides higher scattering contrast and fewer problems for valence-excitation EELS. Specimens that are immune to radiolysis suffer knock-on damage at high current densities, and this form of radiation damage can be reduced or avoided by choosing a low accelerating voltage. Low-voltage STEM with an aberration-corrected objective lens (together with a high-angle dark-field detector and/or EELS) offers atomic resolution and elemental identification from very thin specimens. Conventional TEM can provide atomic resolution in low-voltage phase-contrast images but requires correction of chromatic aberration and preferably an electron-beam monochromator. Many non-conducting (e.g. organic) specimens damage easily by radiolysis and radiation damage then determines the TEM image resolution. For bright-field scattering contrast, low kV can provide slightly better dose-limited resolution if the specimen is very thin (a few nm) but considerably better resolution is possible from a thicker specimen, for which higher kV is required. Use of a phase plate in a conventional TEM offers the most dose-efficient way of achieving atomic resolution from beam-sensitive specimens.

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

    SciTech Connect

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

    2006-03-06

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

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

    PubMed

    Ohya, Kaoru; Ishitani, Tohru

    2003-01-01

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

  16. Electron microscopic features of skin in neurometabolic disorders.

    PubMed

    Ceuterick, C; Martin, J J

    1992-10-01

    Skin biopsy may contribute to the clinical diagnosis of neurometabolic disorders. It is an easy and much less traumatic procedure than brain, rectal, peripheral nerve and skeletal muscle biopsies. The method is informative and not too time-consuming for an experienced examiner. Differential diagnosis is possible in most storage disorders since the ultrastructure of the storage is virtually typical in lysosomal and in nonlysosomal diseases. The storage has a particular distribution with characteristic ultrastructural patterns in the various cell types. Skin biopsy plays a major diagnostic role when clinical features are atypical for a storage disorder, to discover new phenotypic variants of known enzymatic deficiencies or when the biochemical defect has not yet been determined. It can be used as a screening procedure to orientate the investigations, to suggest specific biochemical assays on cultured fibroblasts or other tissues or body fluids. It can be applied to detect "presymptomatic" patients in affected families. Other disorders of the nervous system should be investigated in the future to ascertain whether skin biopsies could possibly be used for diagnostic purposes. Thorough knowledge of the morphological features of these disorders may also improve the understanding of their pathogenesis, shed some light on the underlying basic defects and control the results of therapy.

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

    PubMed

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

    2012-10-01

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

  18. Supravital uptake of methylene blue by dendritic cells within stratified squamous epithelia: a light and electron microscope study.

    PubMed

    Müller, T

    1996-03-01

    Electron microscopic data on methylene blue staining of dendritic cells in the epithelia of the soft palate and skin of the mouse after supravital dye injection are presented. The ultra-structural details were compared with corresponding light microscopic findings. Methylene blue stained tissue was fixed by immersion in a paraformaldehyde-glutaraldehyde solution containing phosphomolybdic acid. The ensuing dye precipitate was stabilized by ammonium heptamolybdate. The light microscopic investigation revealed that selective staining of dendritic cells depended on the presence of ambient oxygen. In addition, delicate morphological characteristics, like spinous structures of the dendrites, were visible. Some cells also showed terminal enlargements of the dendrites close to the surface of the epithelium. In general, visualization of morphological detail was superior to that obtained by conventional histological and immunohistochemical procedures. Nerve fibers were also stained within the epithelium as well as the subepithelial connective tissue. At the electron microscopic level, the dye was clearly identified as an electron dense precipitate that accumulated primarily within the cytoplasm near the plasma membrane. Furthermore, it was bound to the chromatin of the nuclei. No significant staining of mitochondria or other organelles was seen. Within the cytoplasm, the oxygen-dependent binding sites may be associated with heme proteins that attract both the dye in its reduced lipophilic leuco form and oxygen, followed by generation of oxygen radicals and a reoxidation of the leuco form to the cationic blue dye. Because of its selectivity for intraepithelial dendritic cells, the method described here supplements immunocytochemical procedures at both the light and electron microscopic levels.

  19. Spectroscopic and microscopic investigations of phthalocyanine aggregates on Gold(111)

    NASA Astrophysics Data System (ADS)

    Nishida, Krista Rachel Akiko

    Self-assembled organic pi systems are of interest because of their potential applications in light harvesting and electron transfer. Phthalocyanines (Pc) demonstrate desirable photonic and electronic properties, thus making them excellent candidates for functional nanostructures. The specific focus of this research has been the nanoscale aggregation of a metal-free organic dye, tetrasulfonic acid phthalocyanine (TSPc) and includes the use of UV-visible Spectroscopy, Resonance Light Scattering Spectroscopy (RLS), X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and ambient and ultra-high-vacuum Scanning Tunneling Microscopy (STM) and Scanning Tunneling Spectroscopy (STS). The UV-visible absorption studies show that TSPc aggregates upon dissolution in water and obeys Beer's Law within the concentration range of 10 -7M to 10-4M, indicating that TSPc concentration has no further effect on aggregation in aqueous solution. In addition, both ionic strength in NaCl and pH changes in the presence of NaOH, HCl or acetic acid (HAc) do affect aggregation. The RSL studies confirm these effects of pH only in the presence of HAc. The XPS studies show that the ratio of non-protonated to protonated nitrogens does not change with decreasing solution pH. STM images of TSPc deposited from pH<1 solutions reveal ordered branched web-like assemblies hundreds of nanometers in length, generally 2 nm tall and having variable widths. STM imaging shows TSPc aggregates decrease in order as pH increases. STM images of TSPc deposited from solutions with pH>10 show monolayer coverage of TSPc in salt form. High-resolution UHV-STM images of TSPc aggregates deposited from pH 0 solution on Au(111) reveal detailed coherent columnar architecture with the phthalocyanine macrocycles orientated parallel to the substrate surface. OMTS was used to identify the HOMO and LUMO of the TSPc aggregates and the results are contrasted with the same molecular states in unsubstituted metallated

  20. A preliminary electron microscopic investigation into the interaction between Aβ1-42 peptide and a novel nanoliposome- coupled retro-inverso peptide inhibitor, developed as a potential treatment for Alzheimer's disease

    NASA Astrophysics Data System (ADS)

    Sherer, M.; Fullwood, N. J.; Taylor, M.; Allsop, D.

    2015-10-01

    Alzheimer's disease (AD) is a progressive neurodegenerative condition that results in severe cognitive and functional decline in sufferers and for which there are currently no effective treatments to halt or reverse disease progression. AD is the most common form of dementia and age is the major risk factor for this disease. With worldwide population structures changing as increasing number of individuals survive into old age, there is urgent need for novel disease modifying treatments for this condition, which has profound effects upon sufferers in addition to those around them. Some of us have previously developed a peptide inhibitor of Aβ1-42 aggregation (RI-OR2-TAT) that has been shown to reduce Aβ1-42 pathology in vivo in mouse models of AD. ∼1690 copies of RI-OR2-TAT have been covalently attached to nanoliposome carrier particles forming Peptide Inhibitor NanoParticles (PINPs), and this study investigated the effect of PINPs upon Aβ1-42 aggregation at the molecular level. Our results show that PINPs are able to reduce Aβ1-42 aggregation and do so by binding early (oligomers) and late (fibrillar) stage aggregates. These results highlight the ability of PINPs to disrupt the formation of multiple Aβ1-42 aggregates capable of causing neurotoxicity and thus provide a strong case for PINPs to be carried forward into early stage clinical trials as a novel therapeutic option for the treatment of AD.

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

    NASA Technical Reports Server (NTRS)

    Loyd, Jody; Gregory, Don; Gaskin, Jessica

    2016-01-01

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

  2. 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.

  3. 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 ...

  4. 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.

  5. A study of the small intestinal mucosa using the scanning electron microscope

    PubMed Central

    Marsh, M. N.; Swift, J. A.

    1969-01-01

    In this paper we describe the features of small intestinal structure in normal control subjects using the scanning electron microscope. ImagesFIGS. 2a and 2bFIG. 3FIG. 4FIG. 5FIG. 6FIGS. 7a and 7bFIG. 8FIG. 9FIG. 10FIG. 11FIG. 12FIG. 13FIG. 14FIG. 15 PMID:5358588

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

    PubMed

    Schémann, J F

    1987-01-01

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

  7. 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.

  8. An x-ray photoemission electron microscope using an electron mirror aberration corrector for the study of complex materials

    NASA Astrophysics Data System (ADS)

    Feng, J.; Forest, E.; MacDowell, A. A.; Marcus, M.; Padmore, H.; Raoux, S.; Robin, D.; Scholl, A.; Schlueter, R.; Schmid, P.; Stöhr, J.; Wan, W.; Wei, D. H.; Wu, Y.

    2005-04-01

    A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed at the advanced light source (ALS). An electron mirror combined with a sophisticated magnetic beam separator is used to provide simultaneous correction of spherical and chromatic aberrations. Installed on an elliptically polarized undulator beamline, PEEM3 will be operated with very high spatial resolution and high flux to study the composition, structure, electric and magnetic properties of complex materials.

  9. A design for a subminiature, low energy scanning electron microscope with atomic resolution

    SciTech Connect

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

    2009-01-01

    We describe a type of scanning electron microscope that works by directly imaging the electron field-emission sites on a nanotip. Electrons are extracted from the nanotip through a nanoscale aperture, accelerated in a high electric field, and focused to a spot using a microscale Einzel lens. If the whole microscope (accelerating section and lens) and the focal length are both restricted in size to below 10 {mu}m, then computer simulations show that the effects of aberration are extremely small and it is possible to have a system with approximately unit magnification at electron energies as low as 300 eV. Thus a typical emission site of 1 nm diameter will produce an image of the same size, and an atomic emission site will give a resolution of 0.1-0.2 nm (1-2 A). Also, because the beam is not allowed to expand beyond 100 nm in diameter, the depth of field is large and the contribution to the beam spot size from chromatic aberrations is less than 0.02 nm (0.2 A) for 500 eV electrons. Since it is now entirely possible to make stable atomic sized emitters (nanopyramids), it is expected that this instrument will have atomic resolution. Furthermore the brightness of the beam is determined only by the field emission and can be up to 1x10{sup 6} times larger than in a typical (high energy) electron microscope. The advantages of this low energy, bright-beam electron microscope with atomic resolution are described and include the possibility of it being used to rapidly sequence the human genome from a single strand of DNA as well as being able to identify atomic species directly from the elastic scattering of electrons.

  10. Facilities for in situ ion beam studies in transmission electron microscopes

    SciTech Connect

    Allen, C.W.; Ohnuki, S.; Takahashi, H.

    1993-08-01

    Interfacing an ion accelerator to a transmission electron microscope (TEM) allows the analytical functions of TEM imaging and electron diffraction from very small regions to be employed during ion-irradiation effects studies. At present there are ten such installations in Japan, one in France and one in the USA. General specifications of facilities which are operational in 1993 are summarized, and additional facilities which are planned or being proposed are briefly described.

  11. In situ study of single-walled carbon nanotube growth in an environmental scanning electron microscope.

    PubMed

    Mehedi, H-A; Ravaux, J; Tahir, S; Podor, R; Jourdain, V

    2016-12-16

    Monitoring individual single-walled carbon nanotubes (SWCNTs) during their growth is a highly sought-after goal in view of understanding the processes involved in the nucleation, elongation and termination which ultimately control the diameter and chiral selectivity. Here, we report on the first truly in situ observations of SWCNT growth in an environmental scanning electron microscope (ESEM). The CNT growth from lithographically patterned catalysts was investigated as a function of the catalyst type (Fe, Co or Ni), temperature, type of precursor (ethanol or acetylene), gas phase composition and pressure, and pretreatment conditions, and we report on the most appropriate conditions for SWCNT growth in ESEM conditions. We show that this approach allows the observation at the submicron scale of the different steps of the nanotube synthesis including the catalyst reduction, the growth and percolation of the nanotube network, and the deposition of individual nanotubes grown in the gas phase on the substrate. Despite these obvious advantages, we identified a few limitations which will need to be tackled for fully taking advantage of the approach, for instance for monitoring the growth of individual SWCNTs by ESEM, including the short lifetime of the catalyst nanoparticles, the preference for kite growth (by opposition to surface growth) and the influence of the electron beam on the nanotube growth.

  12. Correction and alignment strategies for the beam separator of the photoemission electron microscope 3 (PEEM3)

    NASA Astrophysics Data System (ADS)

    Schmid, Peter; Feng, Jun; Padmore, Howard; Robin, David; Rose, Harald; Schlueter, Ross; Wan, Weishi; Forest, Étienne; Wu, Ying

    2005-02-01

    A high-resolution aberration-corrected photoemission electron microscope (PEEM3) will be installed on an undulator beamline at the Advanced Light Source at the Lawrence Berkeley National Laboratory. The aim of this instrument is to provide a substantial flux and resolution improvement by employing an electron mirror for correcting both the third-order spherical aberration and the primary chromatic aberration. In order to utilize this concept of correction, a beam separator is a prerequisite. Crucial to achieving a resolution of 5nm for the high-resolution mode, and a 16-fold increase in throughput at the same resolution as its predecessor, PEEM2, specified as 20nm at 2% transmission, for the high flux mode is the double-symmetric design of the beam separator, which eliminates all the second-order geometric aberrations. Nonetheless, substantial tuning capabilities must be incorporated into the PEEM3 design to compensate for both systematic and random errors. In this article, we investigate how to correct for nonsystematic imperfections and for systematic uncertainties in the accuracy of the magnetic fields and focus on how degradation of the resolution and the field of view can be minimized. Finally, we outline a tentative correction strategy for PEEM3.

  13. Combined light and electron microscopic visualization of neuropeptides and their receptors in central neurons.

    PubMed

    Salio, Chiara; Lossi, Laura; Merighi, Adalberto

    2011-01-01

    The study of neuronal connections and neuron to neuron (or neuron to glia) communication is of fundamental importance in understanding brain structure and function. Therefore, ultrastructural investigation by the use of immunocytochemical techniques is a really precious tool to obtain an exact map of the localization of neurotransmitters (neuropeptides) and their receptors at different types of synapses. However, in immunocytochemical procedures one has always to search for the optimal compromise between structural preservation and retention of antigenicity. This is often made difficult by the need to localize not only small transmitter molecules, as in the case of transmitter amino acids and neuropeptides, but also their specific receptors that are usually large proteins very sensitive to fixation procedures. We describe here a preembedding procedure employing the Fluoronanogold™ reagent, a probe consisting of fluorescein-tagged antibodies conjugated with ultrasmall gold particles that can be made visible under the electron microscope by a gold intensification procedure. This technique permits correlative fluorescence and electron microscopy observations, providing a very useful tool for the study of neuronal connectivity. Moreover, the Fluoronanogold™ procedure can be combined with conventional postembedding immunogold techniques in multiple labeling studies.

  14. In situ study of single-walled carbon nanotube growth in an environmental scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Mehedi, H.-A.; Ravaux, J.; Tahir, S.; Podor, R.; Jourdain, V.

    2016-12-01

    Monitoring individual single-walled carbon nanotubes (SWCNTs) during their growth is a highly sought-after goal in view of understanding the processes involved in the nucleation, elongation and termination which ultimately control the diameter and chiral selectivity. Here, we report on the first truly in situ observations of SWCNT growth in an environmental scanning electron microscope (ESEM). The CNT growth from lithographically patterned catalysts was investigated as a function of the catalyst type (Fe, Co or Ni), temperature, type of precursor (ethanol or acetylene), gas phase composition and pressure, and pretreatment conditions, and we report on the most appropriate conditions for SWCNT growth in ESEM conditions. We show that this approach allows the observation at the submicron scale of the different steps of the nanotube synthesis including the catalyst reduction, the growth and percolation of the nanotube network, and the deposition of individual nanotubes grown in the gas phase on the substrate. Despite these obvious advantages, we identified a few limitations which will need to be tackled for fully taking advantage of the approach, for instance for monitoring the growth of individual SWCNTs by ESEM, including the short lifetime of the catalyst nanoparticles, the preference for kite growth (by opposition to surface growth) and the influence of the electron beam on the nanotube growth.

  15. Development of a surface conductivity measurement system for ultrahigh vacuum transmission electron microscope

    SciTech Connect

    Minoda, H.; Hatano, K.; Yazawa, H.

    2009-11-15

    The surface conductivity measurement system using a micro-four-point probe (M4PP) had been developed for the ultrahigh vacuum transmission electron microscope (UHV-TEM). Since the current distribution in the sample crystals during the current voltage measurement by the M4PP is localized within the depth of several micrometers from the surface, the system is sensitive to the surface conductivity, which is related with the surface superstructure. It was installed in the main chamber of the TEM and the surface conductivity can be measured in situ. The surface structures were observed by reflection electron microscopy and diffraction (REM-RHEED). REM-RHEED enables us to observe the surface superstructures and their structure defects such as surface atomic steps and domain boundaries of the surface superstructure. Thus the effects of the defects on the surface conductivity can be investigated. In the present paper we present the surface conductivity measurement system and its application to the Si(111)-{radical}(3)x{radical}(3)-Ag surface prepared on the Si(111) vicinal surfaces. The result clearly showed that the surface conductivity was affected by step configuration.

  16. [Regulatory elements in the skin epithelium of Saccoglossus mereschkowskii (Enteropneusta, Hemichordata): electron microscopic and immunocytochemical study].

    PubMed

    Stoliarova, M V; Val'kovich, E I

    2013-01-01

    The aim of this investigation was to demonstrate the regulatory elements in the skin epithelium of Enteropneusta which are supposed to be related to the chordate ancestors. Using electron microscopy, it was found that in the skin epithelium of a representative of enteropneusts Saccoglossus mereschkowskii, the basal parts of some epitheliocytes took part in formation of a nerve layer. These cells were considered as receptor ciliated cells. The granular epithelial cells were shown to release secretion according to both exocrine and endocrine mechanism; these cells were characterized as endocrine-like regulatory cells. Fine granular cells possibly represent special receptor-endocrine-like cell type. The immunocytochemical detection of FMRFamid neuropeptide localization in histological sections confirmed the electron microscopic data on the presence of receptor and endocrine-like cells in the epithelium. It is suggested that the skin epithelium of Enteropneusta contains a peculiar neuro-endocrine regulatory system that is represented by receptor cells, receptor-endocrine-like cells of an open type and nerve elements of the nerve layer.

  17. In situ scanning electron microscope peeling to quantify surface energy between multiwalled carbon nanotubes and graphene.

    PubMed

    Roenbeck, Michael R; Wei, Xiaoding; Beese, Allison M; Naraghi, Mohammad; Furmanchuk, Al'ona; Paci, Jeffrey T; Schatz, George C; Espinosa, Horacio D

    2014-01-28

    Understanding atomic interactions between constituents is critical to the design of high-performance nanocomposites. Here, we report an experimental-computational approach to investigate the adhesion energy between as-produced arc discharge multiwalled carbon nanotubes (MWCNTs) and graphene. An in situ scanning electron microscope (SEM) experiment is used to peel MWCNTs from graphene grown on copper foils. The force during peeling is obtained by monitoring the deflection of a cantilever. Finite element and molecular mechanics simulations are performed to assist the data analysis and interpretation of the results. A finite element analysis of the experimental configuration is employed to confirm the applicability of Kendall's peeling model to obtain the adhesion energy. Molecular mechanics simulations are used to estimate the effective contact width at the MWCNT-graphene interface. The measured surface energy is γ = 0.20 ± 0.09 J·m(-2) or γ = 0.36 ± 0.16 J·m(-2), depending on the assumed conformation of the tube cross section during peeling. The scatter in the data is believed to result from an amorphous carbon coating on the MWCNTs, observed using transmission electron microscopy (TEM), and the surface roughness of graphene as characterized by atomic force microscopy (AFM).

  18. Electron microscopic examination of effects of bogma raki and walnut on cochlea: an experimental study.

    PubMed

    Cevik, C; Ozler, G S; Arli, C; Tatar, I; Sargon, M F; Zeren, C; Yonden, Z; Akoglu, E

    2015-03-01

    Illegal alcohol beverages known as bogma raki in our country are consumed widely in our region. The studies investigating the relationship between alcohol consumption and hearing ability report different results. In this study, we aimed to investigate the toxic effects of bogma raki that contains neurotoxic substances on cochlea by electron microscopy. To the best of our knowledge, this study is the first in the literature. A total of 48 Wistar male albino rats (aged 12-16 weeks and weighing 200-240 g) were used in the study. The rats were divided into 4 groups with 12 animals in each group. The groups include control, bogma raki, walnut, and walnut + bogma raki groups. Bogma raki (30% v/v, 9.2 ml kg(-1) day(-1)) is added to drinking water of rats in bogma raki group (n = 12) for 4 weeks. Walnut group rats (n = 12) are fed with standard rat food and walnut without limitation (10 g kg(-1) day(-1)). Bogma raki + walnut group rats (n = 12) are fed with standard rat food and walnut and bogma raki is added to drinking water. The cochleas were dissected and removed en bloc and examined by electron microscopy. Perineuronal oedema around neurons of spiral ganglion and hairy cells of organ of Corti were present in the bogma raki group, walnut group and bogma raki + walnut group under electron microscopic examination. Comparing these three groups, there were no differences in the ultrastructural pathological changes. In the ultrastructural examination of the myelinated axons forming cochlear nerve, no ultrastructural pathology was detected in all the groups.

  19. 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

  20. 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.

  1. High spatial resolution absorption contrast imaging with electron-beam excitation assisted optical microscope

    NASA Astrophysics Data System (ADS)

    Inami, Wataru; Fukuta, Masahiro; Kawata, Yoshimasa; Terakawa, Susumu

    2016-11-01

    We present high spatial-resolution label-free imaging with an electron-beam excitation-assisted optical microscope (EXA microscope). The EXA microscope improves the spatial resolution down to 100 nm. To realize the high spatial resolution, a nanoscale optical spot is generated by irradiating a fluorescent thin film with a focused electron beam whose spot size is less than 10 nm. The size of the optical spot becomes smaller than the diffraction limited spot size and is reduced to about 100 nm, because the light emission is localized in nanometer-sized region. In this microscopy, it is not necessary to label a specimen for imaging beyond the diffraction limit of the light. The specimen stage is separated from the vacuum chamber of the scanning electron microscope by the fluorescent thin film and a specimen under atmospheric pressure can be imaged. We demonstrated that the high spatial resolution absorption contrast imaging of the crystal of vitamin B9 having absorption at UV wavelengths. The absorption wavelength matches with the wavelength of the emission of the fluorescent thin film we deposited. The fine crystal structure was imaged beyond the optical diffraction limit. The image contrast corresponded with the thickness of the crystal measured with an atomic force microscope (AFM). The illumination light is absorbed with the vitamin B9 crystal and the intensity of the transmitted light depends on the thickness of the vitamin B9 crystal. The EXA microscope is useful for analysis of growth of a crystal, bio-imaging, and so on.

  2. Electron microscope studies. Progress report, 1 July 1964--1 June 1992

    SciTech Connect

    Crewe, A.V.; Kapp, O.H.

    1992-07-01

    This is a report covering the research performed in the Crewe laboratory between 1964 and 1992. Because of limitations of space we have provided relatively brief summaries of the major research directions of the facility during these years. A complete bibliography has been included and we have referenced groups of pertinent publications at the beginning of each section. This report summarizes our efforts to develop better electron microscopes and chronicles many of the experimental programs, in materials science and biology, that acted both as a stimulus to better microscope design and also as a testing ground for many instrumental innovations.

  3. In situ nanomechanical testing of twinned metals in a transmission electron microscope

    DOE PAGES

    Li, Nan; Wang, Jiangwei; Mao, Scott; ...

    2016-04-01

    This paper focuses on in situ transmission electron microscope (TEM) characterization to explore twins in face-centered-cubic and body-centered-cubic monolithic metals, and their impact on the overall mechanical performance. Taking advantage of simultaneous nanomechanical deformation and nanoscale imaging using versatile in situ TEM tools, direct correlation of these unique microscopic defects with macroscopic mechanical performance becomes possible. This article summarizes recent evidence to support the mechanisms related to strengthening and plasticity in metals, including nanotwinned Cu, Ni, Al, Au, and others in bulk, thin film, and nanowire forms.

  4. In situ nanomechanical testing of twinned metals in a transmission electron microscope

    SciTech Connect

    Li, Nan; Wang, Jiangwei; Mao, Scott; Wang, Haiyan

    2016-04-01

    This paper focuses on in situ transmission electron microscope (TEM) characterization to explore twins in face-centered-cubic and body-centered-cubic monolithic metals, and their impact on the overall mechanical performance. Taking advantage of simultaneous nanomechanical deformation and nanoscale imaging using versatile in situ TEM tools, direct correlation of these unique microscopic defects with macroscopic mechanical performance becomes possible. This article summarizes recent evidence to support the mechanisms related to strengthening and plasticity in metals, including nanotwinned Cu, Ni, Al, Au, and others in bulk, thin film, and nanowire forms.

  5. Absorption contrast imaging beyond the diffraction limit with electron-beam excitation assisted optical microscope

    NASA Astrophysics Data System (ADS)

    Inami, Wataru; Fukuta, Masahiro; Kawata, Yoshimasa; Terakawa, Susumu

    2017-04-01

    We demonstrated that the high spatial resolution absorption contrast imaging of the crystal of vitamin B9 having absorption at UV wavelengths. The absorption wavelength matches with the wavelength of the emission of the fluorescent thin film of an electron-beam excitation assisted (EXA) optical microscope. The fine crystal structure was imaged beyond the optical diffraction limit. The image contrast corresponded with the thickness of the crystal. The illumination light is absorbed with the vitamin B9 crystal and the intensity of the transmitted light depends on the thickness of the vitamin B9 crystal. The EXA optical microscope is useful for analysis of growth of a crystal, bioimaging, and so on.

  6. Modeling the acceleration field and objective lens for an aberration corrected photoemission electron microscope

    NASA Astrophysics Data System (ADS)

    Feng, J.; Padmore, H.; Wei, D. H.; Anders, S.; Wu, Y.; Scholl, A.; Robin, D.

    2002-03-01

    The modeling of the optical properties of the acceleration field and objective lens of a photoemission electron microscope (PEEM) is presented. Theory to calculate the aberrations of the extraction field was derived, and extended to include relativistic effects. An analysis of the microscope's electron optical performance and aberrations has been performed using an analytical model as well as a ray tracing method. Ray tracing has the flexibility needed for the assessment of aberrations where the geometry is too complex for analytical methods. This work shows that in the case of a simple PEEM front end of the acceleration gap and objective lens, the all orders ray tracing and full analytical treatments agree to very high precision. This allows us now to use the ray tracing method in situations where analytical methods are difficult, such as an aberration compensating electron mirror.

  7. 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.

  8. 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.

  9. Reduced Humidity Effects on Probe Nano-Oxidation Investigated Using Dynamic Force Microscope

    NASA Astrophysics Data System (ADS)

    Kuramochi, Hiromi; Ando, Kazunori; Tokizaki, Takashi; Yokoyama, Hiroshi

    2006-03-01

    Humidity effects on nano-oxidation are investigated using a dynamic force microscope in the humidity range of 30-60%. Oxide size and detected faradaic current increased with relative humidity and applied voltage. The aspect ratios of fabricated oxides at various humidities are approximately of the same magnitude. Scanning probe microscope nano-oxidation in the dynamic mode is less subject to the relative humidity than that in the contact mode.

  10. Electron-beam irradiation induced conductivity in ZnS nanowires as revealed by in situ transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Liu, Baodan; Bando, Yoshio; Wang, Mingsheng; Zhi, Chunyi; Fang, Xiaosheng; Tang, Chengchun; Mitome, Masanori; Golberg, Dmitri

    2009-08-01

    Electron transport variations in individual ZnS nanowires synthesized through a chemical vapor deposition process were in situ studied in transmission electron microscope under convergent electron-beam irradiation (EBI). It was found that the transport can dramatically be enhanced using proper irradiation conditions. The conductivity mechanism was revealed based on a detailed study of microstructure and composition evolutions under irradiation. EBI-induced Zn-rich domains' appearance and related O doping were mainly responsible for the conductivity improvements. First-principles theoretical calculations additionally indicated that the generation of midbands within a ZnS band gap might also contribute to the improved conductivity.

  11. 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.

  12. 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.

  13. Use of emission electron microscope for potential mapping in semiconductor microelectronics.

    PubMed

    Nepijko, S A; Sedov, N N; Schönhense, G; Escher, M

    2002-05-01

    An emission electron microscope was used for visualization and measurement of the distribution of electric fields and potentials on the surface under study. The contrast of microfields is caused by the fact that slow-moving electrons emitted from the object surface are deflected by these fields. The measurements were performed on a p-n junction to which a voltage was applied. It is shown that the type of contrast from the p-n junction can be reversed depending on the position of the contrast aperture restricting the electron beam. The same result was obtained by means of a computer simulation.

  14. 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

    2016-12-27

    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.

  15. 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.

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

    PubMed

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

    2014-11-01

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

  17. Light and electron microscopic features of early and late phase radiation-induced proctitis

    SciTech Connect

    Haboubi, N.Y.; Schofield, P.F.; Rowland, P.L.

    1988-10-01

    The light and electron microscopic features of rectal biopsies from 10 symptomatic patients treated with irradiation for pelvic malignancies are detailed. They are divided into two groups. Group I: biopsies taken during or shortly after the course of irradiation (six patients). Group II: biopsies taken 4 months or more after course completion (four patients). The distinguishing light microscopic features in the first group are epithelial meganucleosis, lack of mitotic activity, and patchy fibroblastic proliferation in the lamina propria. The blood vessels appear normal. In the second group, there are severe vascular changes characterized by narrowing of the arterioles by subintimal fibrosis, telangiectasia of capillaries and post-capillary venules, endothelial degeneration, and platelet thrombi formation. These vascular changes are always associated with severe fibrosis of the lamina propria and crypt distortion. The ultrastructural and light microscopic findings indicate that the cellular epithelial reaction and fibroblastic proliferation antedate the vascular injury, and the latter has no role in the acute phase reaction.

  18. The effects of Korean propolis against foodborne pathogens and transmission electron microscopic examination.

    PubMed

    Kim, Youn-Ha; Chung, Hyun-Jung

    2011-10-01

    This study was performed to evaluate the effects of Korean propolis against foodborne pathogens and spores of Bacillus cereus and to investigate the antimicrobial activity against B. cereus structure by transmission electron microscopy (TEM). The antimicrobial effects of the Korean propolis were tested against foodborne pathogens including Gram-positive (B. cereus, Listeria monocytogenes and Staphylococcus aureus) and Gram-negative (Salmonella typhimurium, Escherichia coli and Pseudomonas fluorescence) bacteria by agar diffusion assay. Gram-positive bacteria were more sensitive than were Gram-negative bacteria. The vegetative cells of B. cereus were the most sensitive among the pathogens tested with minimum inhibitory concentration (MIC) of 0.036 mg/μl of propolis on agar medium. Based on MIC, sensitivity of vegetative cells of B. cereus and its spores was tested in a nutrient broth with different concentrations of propolis at 37°C. In liquid broth, treatment with 1.8 mg/ml propolis showed bactericidal effect against B. cereus. B. cereus vegetative cells exposed to 7.2mg/ml of propolis lost their viability within 20 min. Against spores of B. cereus, propolis inhibited germination of spores up to 30 hours, compared to control at higher concentration than vegetative cells yet acted sporostatically. The bactericidal and sporostatic action of propolis were dependent on the concentration of propolis used and treatment time. Electron microscopic investigation of propolis-treated B. cereus revealed substantial structural damage at the cellular level and irreversible cell membrane rupture at a number of locations with the apparent leakage of intracellular contents. The antimicrobial effect of propolis in this study suggests potential use of propolis in foods. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Quantum coherent optical phase modulation in an ultrafast transmission electron microscope.

    PubMed

    Feist, Armin; Echternkamp, Katharina E; Schauss, Jakob; Yalunin, Sergey V; Schäfer, Sascha; Ropers, Claus

    2015-05-14

    Coherent manipulation of quantum systems with light is expected to be a cornerstone of future information and communication technology, including quantum computation and cryptography. The transfer of an optical phase onto a quantum wavefunction is a defining aspect of coherent interactions and forms the basis of quantum state preparation, synchronization and metrology. Light-phase-modulated electron states near atoms and molecules are essential for the techniques of attosecond science, including the generation of extreme-ultraviolet pulses and orbital tomography. In contrast, the quantum-coherent phase-modulation of energetic free-electron beams has not been demonstrated, although it promises direct access to ultrafast imaging and spectroscopy with tailored electron pulses on the attosecond scale. Here we demonstrate the coherent quantum state manipulation of free-electron populations in an electron microscope beam. We employ the interaction of ultrashort electron pulses with optical near-fields to induce Rabi oscillations in the populations of electron momentum states, observed as a function of the optical driving field. Excellent agreement with the scaling of an equal-Rabi multilevel quantum ladder is obtained, representing the observation of a light-driven 'quantum walk' coherently reshaping electron density in momentum space. We note that, after the interaction, the optically generated superposition of momentum states evolves into a train of attosecond electron pulses. Our results reveal the potential of quantum control for the precision structuring of electron densities, with possible applications ranging from ultrafast electron spectroscopy and microscopy to accelerator science and free-electron lasers.

  20. Quantum coherent optical phase modulation in an ultrafast transmission electron microscope

    NASA Astrophysics Data System (ADS)

    Feist, Armin; Echternkamp, Katharina E.; Schauss, Jakob; Yalunin, Sergey V.; Schäfer, Sascha; Ropers, Claus

    2015-05-01

    Coherent manipulation of quantum systems with light is expected to be a cornerstone of future information and communication technology, including quantum computation and cryptography. The transfer of an optical phase onto a quantum wavefunction is a defining aspect of coherent interactions and forms the basis of quantum state preparation, synchronization and metrology. Light-phase-modulated electron states near atoms and molecules are essential for the techniques of attosecond science, including the generation of extreme-ultraviolet pulses and orbital tomography. In contrast, the quantum-coherent phase-modulation of energetic free-electron beams has not been demonstrated, although it promises direct access to ultrafast imaging and spectroscopy with tailored electron pulses on the attosecond scale. Here we demonstrate the coherent quantum state manipulation of free-electron populations in an electron microscope beam. We employ the interaction of ultrashort electron pulses with optical near-fields to induce Rabi oscillations in the populations of electron momentum states, observed as a function of the optical driving field. Excellent agreement with the scaling of an equal-Rabi multilevel quantum ladder is obtained, representing the observation of a light-driven `quantum walk' coherently reshaping electron density in momentum space. We note that, after the interaction, the optically generated superposition of momentum states evolves into a train of attosecond electron pulses. Our results reveal the potential of quantum control for the precision structuring of electron densities, with possible applications ranging from ultrafast electron spectroscopy and microscopy to accelerator science and free-electron lasers.

  1. Investigation of Electronically Tunable Optical Filters.

    DTIC Science & Technology

    aperture characteristics, and the investigation of possibilities of its use to construct an electronically tunable laser. A separate paper is included, titled: CaMoO4 Electronically Tunable Optical Filter.

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

    PubMed

    Meller, S T; Dennis, B J

    1993-09-01

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

  3. Electronic structure investigations of quasicrystals

    NASA Astrophysics Data System (ADS)

    Rotenberg, E.; Theis, W.; Horn, K.

    2004-08-01

    We present a review of the determination of density of states (DOS) of quasicrystals using valence band photoemission spectroscopy. The absence of fine or spiky structure in the angle-integrated DOS of quasicrystals suggests the possibility of delocalized electronic states. These were confirmed with angle-resolved photoemission studies, which clearly establish the presence of dispersing features attributed to momentum-dependent bandstructure. Such dispersing states are observed not only for deeper-lying sp states, but also for d-derived bands near the Fermi level. Data from three different high symmetry surfaces of decagonal Al-Ni-Co, an ideal model system, are presented. We find that only a few dominant reciprocal lattice vectors are sufficient to describe the quasiperiodic potential, and the implications for electronic properties are discussed.

  4. 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.

  5. 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.

  6. Interface Between MTA and Dental Bonding Agents: Scanning Electron Microscope Evaluation.

    PubMed

    Cervino, Gabriele; Fiorillo, Luca; Spagnuolo, Gianrico; Bramanti, Ennio; Laino, Luigi; Lauritano, Floriana; Cicciù, Marco

    2017-01-01

    Nowadays, the material that offers the best sealing characteristic in the field of endodontic treatment is the mineral trioxide aggregate (MTA), nevertheless, this material necessities an adhesive bonding agent to perfectly join to the dental surface. The aim of this study was to analyze using a scanning electron microscope (SEM) the possible microgap between the adhesive, MTA, and the dental surface. Fourteen extracted molars were divided into two groups - group A was prepared with MTA-component adhesive and group B was prepared with MTA and composite dual etching. The observations were carried out with a SEM Phenom G2 Pro mode S.E.I. JMP® software was used for statistical analysis, and a t-test was used for evaluating the difference between the two groups. The gap of the areas at higher magnification (1000×) with a size greater than 5 microns in width and 20 microns in length were considered significant, and only group A recorded significant data. The SEM analysis performed in the group A with interposition of adhesive and flow between the dental pulp chamber and MTA demonstrates the presence of a marginal gap of considerable amplitude in the all of the samples investigated.

  7. Study of the thermal degradation mechanism of a composite propellant. [using electron microscopes

    NASA Technical Reports Server (NTRS)

    Schmidt, W. G.

    1975-01-01

    The current experimental program was designed to systematically investigate the role of the oxidizer in the thermal degradation process of composite propellants. The scanning electron microscope (SEM) was used to examine the failure sites in thermally degraded propellant samples. The formulation variables tested were oxidizer purity, oxidizer particle size, and oxidizer to binder bonding agent. The binder, a saturated hydrocarbon, was kept constant throughout the experiments. The oxidizers were: AP, chlorate-doped AP, arsenate-doped AP, and phosphate-doped AP. The oxidizer particle size distribution was 60% of the large fraction and 40% of the small fraction. The bonding agent, when present, was used at the 0.15% level. The data showed that both the oxidizer purity and particle size had an important affect on the thermal degradation process. The affect of the oxidizer particle size was more noticeable at the higher temperature and stress levels. An examination of the failure site, by SEM, of propellants subject to these latter conditions indicated that the fracturing of the large oxidizer particles led to the propellant cracking.

  8. Interface Between MTA and Dental Bonding Agents: Scanning Electron Microscope Evaluation

    PubMed Central

    Cervino, Gabriele; Fiorillo, Luca; Spagnuolo, Gianrico; Bramanti, Ennio; Laino, Luigi; Lauritano, Floriana; Cicciù, Marco

    2017-01-01

    Aims and Objectives: Nowadays, the material that offers the best sealing characteristic in the field of endodontic treatment is the mineral trioxide aggregate (MTA), nevertheless, this material necessities an adhesive bonding agent to perfectly join to the dental surface. The aim of this study was to analyze using a scanning electron microscope (SEM) the possible microgap between the adhesive, MTA, and the dental surface. Material and Methods: Fourteen extracted molars were divided into two groups – group A was prepared with MTA-component adhesive and group B was prepared with MTA and composite dual etching. The observations were carried out with a SEM Phenom G2 Pro mode S.E.I. JMP® software was used for statistical analysis, and a t-test was used for evaluating the difference between the two groups. Results: The gap of the areas at higher magnification (1000×) with a size greater than 5 microns in width and 20 microns in length were considered significant, and only group A recorded significant data. Conclusions: The SEM analysis performed in the group A with interposition of adhesive and flow between the dental pulp chamber and MTA demonstrates the presence of a marginal gap of considerable amplitude in the all of the samples investigated. PMID:28316952

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

    PubMed

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

    2001-12-01

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

  10. Common Bias Readout for TES Array on Scanning Transmission Electron Microscope

    NASA Astrophysics Data System (ADS)

    Yamamoto, R.; Sakai, K.; Maehisa, K.; Nagayoshi, K.; Hayashi, T.; Muramatsu, H.; Nakashima, Y.; Mitsuda, K.; Yamasaki, N. Y.; Takei, Y.; Hidaka, M.; Nagasawa, S.; Maehata, K.; Hara, T.

    2016-07-01

    A transition edge sensor (TES) microcalorimeter array as an X-ray sensor for a scanning transmission electron microscope system is being developed. The technical challenge of this system is a high count rate of ˜ 5000 counts/second/array. We adopted a 64 pixel array with a parallel readout. Common SQUID bias, and common TES bias are planned to reduce the number of wires and the resources of a room temperature circuit. The reduction rate of wires is 44 % when a 64 pixel array is read out by a common bias of 8 channels. The possible degradation of the energy resolution has been investigated by simulations and experiments. The bias fluctuation effects of a series connection are less than those of a parallel connection. Simple calculations expect that the fluctuations of the common SQUID bias and common TES bias in a series connection are 10^{-7} and 10^{-3}, respectively. We constructed 8 SQUIDs which are connected to 8 TES outputs and a room temperature circuit for common bias readout and evaluated experimentally. Our simulation of crosstalk indicates that at an X-ray event rate of 500 cps/pixel, crosstalk will broaden a monochromatic line by about 0.01 %, or about 1.5 eV at 15 keV. Thus, our design goal of 10 eV energy resolution across the 0.5-15 keV band should be achievable.

  11. Driving reversible redox reactions at solid-liquid interfaces with the electron beam of a transmission electron microscope.

    PubMed

    Ahmad, Nabeel; Wang, Guillaume; Nelayah, Jaysen; Ricolleau, Christian; Alloyeau, Damien

    2017-05-04

    Liquid-cell transmission electron microscopy (LCTEM) has opened up a new way to study chemical reactions at the interface between solids and liquids. However, understanding the effects of the electron beam in the liquid cell has been clearly identified as one of the most important challenges to assess correctly and quantitatively LCTEM data. Here we show that the electron beam can be used to drive reversible deposition/dissolution cycles of copper shells over gold nanoparticles in methanol. Besides revealing the influence of irreversible processes on the kinetic of growth/etching cycles, this study of nanostructure behaviour as a function of the dose rate highlights the possibility to switch the oxidising or reducing nature of liquid environment only with the electron beam. The chemical and electronic processes possibly involved in these tunable redox reactions are qualitatively discussed together with their possible impacts on electrochemical LCTEM experiments. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  12. Dacarbazine (DTIC)-induced human liver damage light and electron-microscopic findings.

    PubMed

    Dancygier, H; Runne, U; Leuschner, U; Milbradt, R; Classen, M

    1983-06-01

    The first electron-microscopic description of DTIC-induced human liver injury is presented. A 61-year-old man developed signs of hepatic failure during the second treatment cycle with DTIC for malignant melanoma. Light-microscopic examination revealed extensive centrilobular liver necrosis. Terminal hepatic venules did not show any signs of vasculitis or thrombosis and there was a lack of inflammatory infiltration. At the ultrastructural level intracytoplasmic, membrane-bound, organelle-free vacuoles were found in the hepatocytes. Liver cells showed bleb formation. Bile canaliculi were dilated and their microvilli flattened. In the pericanalicular exoplasm electron-dense fibrillary material, thought to be of microfilamentous origin, accumulated. The patient received 250 mg methylprednisolone i.v. at the very onset of symptoms and was discharged 12 days after the peak rise of transaminases with normal liver parameters.

  13. A New Technique for the Study of Viruses in the Electron Microscope

    PubMed Central

    Morgan, Councilman; Rifkind, Richard A.; Rose, Harry M.

    1963-01-01

    A method is described for the application of immunochemical stains to virus-infected cells in preparation for examination in the electron microscope. Specific antibodies to viral particles and to purified viral antigens have been rendered visible in the electron microscope by conjugation with the ironcontaining protein, ferritin. Examination of vaccinia-infected and influenza-infected cells treated with their specific ferritin-labelled antiserum has revealed the disposition of mature virus and viral precursors during various stages of the infection. Virus particles maturing at the cell surface and within the cytoplasm were specifically tagged and, in the case of influenza virus, the soluble, nucleoprotein viral-precursor was identified in distinct portions of the nucleus. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8

  14. Biological application of Compressed Sensing Tomography in the Scanning Electron Microscope.

    PubMed

    Ferroni, Matteo; Signoroni, Alberto; Sanzogni, Andrea; Masini, Luca; Migliori, Andrea; Ortolani, Luca; Pezza, Alessandro; Morandi, Vittorio

    2016-09-20

    The three-dimensional tomographic reconstruction of a biological sample, namely collagen fibrils in human dermal tissue, was obtained from a set of projection-images acquired in the Scanning Electron Microscope. A tailored strategy for the transmission imaging mode was implemented in the microscope and proved effective in acquiring the projections needed for the tomographic reconstruction. Suitable projection alignment and Compressed Sensing formulation were used to overcome the limitations arising from the experimental acquisition strategy and to improve the reconstruction of the sample. The undetermined problem of structure reconstruction from a set of projections, limited in number and angular range, was indeed supported by exploiting the sparsity of the object projected in the electron microscopy images. In particular, the proposed system was able to preserve the reconstruction accuracy even in presence of a significant reduction of experimental projections.

  15. 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.

  16. Biological application of Compressed Sensing Tomography in the Scanning Electron Microscope

    PubMed Central

    Ferroni, Matteo; Signoroni, Alberto; Sanzogni, Andrea; Masini, Luca; Migliori, Andrea; Ortolani, Luca; Pezza, Alessandro; Morandi, Vittorio

    2016-01-01

    The three-dimensional tomographic reconstruction of a biological sample, namely collagen fibrils in human dermal tissue, was obtained from a set of projection-images acquired in the Scanning Electron Microscope. A tailored strategy for the transmission imaging mode was implemented in the microscope and proved effective in acquiring the projections needed for the tomographic reconstruction. Suitable projection alignment and Compressed Sensing formulation were used to overcome the limitations arising from the experimental acquisition strategy and to improve the reconstruction of the sample. The undetermined problem of structure reconstruction from a set of projections, limited in number and angular range, was indeed supported by exploiting the sparsity of the object projected in the electron microscopy images. In particular, the proposed system was able to preserve the reconstruction accuracy even in presence of a significant reduction of experimental projections. PMID:27646194

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

    SciTech Connect

    Liu Zhanwei; Xie Huimin; Fang Daining; Dai Fulong; Wang Weining; Fang Yan

    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 nanometer 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.

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

    SciTech Connect

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

    2006-01-01

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

  19. Biological application of Compressed Sensing Tomography in the Scanning Electron Microscope

    NASA Astrophysics Data System (ADS)

    Ferroni, Matteo; Signoroni, Alberto; Sanzogni, Andrea; Masini, Luca; Migliori, Andrea; Ortolani, Luca; Pezza, Alessandro; Morandi, Vittorio

    2016-09-01

    The three-dimensional tomographic reconstruction of a biological sample, namely collagen fibrils in human dermal tissue, was obtained from a set of projection-images acquired in the Scanning Electron Microscope. A tailored strategy for the transmission imaging mode was implemented in the microscope and proved effective in acquiring the projections needed for the tomographic reconstruction. Suitable projection alignment and Compressed Sensing formulation were used to overcome the limitations arising from the experimental acquisition strategy and to improve the reconstruction of the sample. The undetermined problem of structure reconstruction from a set of projections, limited in number and angular range, was indeed supported by exploiting the sparsity of the object projected in the electron microscopy images. In particular, the proposed system was able to preserve the reconstruction accuracy even in presence of a significant reduction of experimental projections.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    The study of deformation features has been of great importance to determine deformation mechanisms in quartz. Relevant microstructures in both growth and deformation processes include dislocations, subgrains, subgrain boundaries, Brazil and Dauphiné twins and planar deformation features (PDFs). Dislocations and twin boundaries are most commonly imaged using a transmission electron microscope (TEM), because these cannot directly be observed using light microscopy, in contrast to PDFs. Here, we show that red-filtered cathodoluminescence imaging in a scanning electron microscope (SEM) is a useful method to visualise subgrain boundaries, Brazil and Dauphiné twin boundaries. Because standard petrographic thin sections can be studied in the SEM, the observed structures can be directly and easily correlated to light microscopy studies. In contrast to TEM preparation methods, SEM techniques are non-destructive to the area of interest on a petrographic thin section.

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

    NASA Astrophysics Data System (ADS)

    Cui, Le; Marchand, Éric

    2015-04-01

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

  2. Communication: Investigation of the electron momentum density distribution of nanodiamonds by electron energy-loss spectroscopy

    SciTech Connect

    Feng, Zhenbao; Yang, Bing; Lin, Yangming; Su, Dangsheng

    2015-12-07

    The electron momentum distribution of detonation nanodiamonds (DND) was investigated by recording electron energy-loss spectra at large momentum transfer in the transmission electron microscope (TEM), which is known as electron Compton scattering from solid (ECOSS). Compton profile of diamond film obtained by ECOSS was found in good agreement with prior photon experimental measurement and theoretical calculation that for bulk diamond. Compared to the diamond film, the valence Compton profile of DND was found to be narrower, which indicates a more delocalization of the ground-state charge density for the latter. Combining with other TEM characterizations such as high-resolution transmission electron spectroscopy, diffraction, and energy dispersive X-ray spectroscopy measurements, ECOSS was shown to be a great potential technique to study ground-state electronic properties of nanomaterials.

  3. Looking at DNA through the Electron Microscope: the Work of Jack Griffith

    PubMed Central

    Kresge, Nicole; Simoni, Robert D.; Hill, Robert L.

    2009-01-01

    Electron Microscopic Visualization of the RecA Protein-mediated Pairing and Branch Migration Phases of DNA Strand Exchange (Register, J. C., 3rd, Christiansen, G., and Griffith, J. (1987) J. Biol. Chem. 262, 12812–12820) Formation of DNA Loop Replication Fork Generated by Bacteriophage T7 Replication Proteins (Park, K., Debyser, Z., Tabor, S., Richardson, C. C., and Griffith, J. (1998) J. Biol. Chem. 273, 5260–5270)

  4. A sample holder with integrated laser optics for an ELMITEC photoemission electron microscope

    SciTech Connect

    Gierster, L.; Pape, L.; Ünal, A. A.; Kronast, F.

    2015-02-15

    We present a new sample holder compatible with ELMITEC Photoemission Electron Microscopes (PEEMs) containing an optical lens and a mirror. With the integrated optical elements, a laser beam is focused from the back side of the sample at normal incidence, yielding a minimum spot size of about 1 μm. This opens up new possibilities for local laser excitations in PEEM experiments such as imaging all-optical magnetization switching at a small length scale.

  5. An in situ transmission electron microscope deformation study of the slip transfer mechanisms in metals

    SciTech Connect

    Lee, T.C.; Robertson, I.M.; Birnbaum, H.K. . Dept. of Materials Science and Engineering)

    1990-09-01

    The slip transfer mechanisms across grain boundaries in 310 stainless steel, high-purity aluminum, and a Ni-S alloy have been studied by using the in situ transmission electron microscope (TEM) deformation technique. Several interactions between mobile lattice dislocations and grain boundaries have been observed, including the transfer and generation of dislocations at grain boundaries and the nucleation and propagation of a grain boundary crack. Quantitative condition have been established to correctly predict the slip transfer mechanism.

  6. Microscopic Electronic and Mechanical Properties of Ultra-Thin Layered Materials

    DTIC Science & Technology

    2016-07-25

    AFRL-AFOSR-VA-TR-2016-0264 MICROSCOPIC ELECTRONIC AND MECHANICAL PROPERTIES OF ULTRA-THIN LAYERED MATERIALS Abhay Pasupathy THE TRUSTEES OF COLUMBIA...MECHANICAL PROPERTIES OF ULTRA-THIN LAYERED MATERIALS 5b. GRANT NUMBER FA9550-11-1-0010 5c. PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Abhay...of ultra-thin (few layer) crystalline materials , commonly referred to as 2D materials . The technical approach used was to perform atomic-resolution

  7. A sample holder with integrated laser optics for an ELMITEC photoemission electron microscope.

    PubMed

    Gierster, L; Pape, L; Ünal, A A; Kronast, F

    2015-02-01

    We present a new sample holder compatible with ELMITEC Photoemission Electron Microscopes (PEEMs) containing an optical lens and a mirror. With the integrated optical elements, a laser beam is focused from the back side of the sample at normal incidence, yielding a minimum spot size of about 1 μm. This opens up new possibilities for local laser excitations in PEEM experiments such as imaging all-optical magnetization switching at a small length scale.

  8. Electron microscopic observations of terminals of functionally identified afferent fibers in cat spinal cord.

    PubMed

    Egger, M D; Freeman, N C; Malamed, S; Masarachia, P; Proshansky, E

    1981-02-23

    Using the method of intra-axonal injection of horseradish peroxidase, functionally identified afferent fibers from three slowly adapting (Type I) receptors and one Pacinian corpuscle in the glabrous skin of the hind paw of the cat were stained. Electron microscopic observation of the terminals of these fibers revealed predominantly axodendritic asymmetric synapses containing round, clear vesicles. Multiple synapses on a single dendrite were observed, separated by as little as 900 mm from one another.

  9. Defect tracking for nanoimprint lithography using optical surface scanner and scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Yu, Zhaoning; Kurataka, Nobuo; Tran, Hieu; Gauzner, Gene

    2016-09-01

    Fast optical surface scanners are used in combination with high-resolution scanning electron microscopes to facilitate the identification and tracking of nanoimprint defects. We have confirmed that hard particles cause permanent template damages during imprint, resulting in repeating imprint defects. Since contaminants encountered during imprint are dominated by hard metal oxide particles capable of causing such damage, stringent pre-imprint substrate screening is a critical requirement in a manufacturing environment.

  10. Steel Hardness Effects in Boundary Lubricated Sliding: An In-Situ SEM (Scanning Electron Microscope) Study

    DTIC Science & Technology

    1988-01-01

    in a scanning electron microscope (SEM). Through modifications to theSEM, these experiments could be run with a thin film of hydrocarbon oil applied to...as the number of sliding passes increases, plus agglomeration of wear debris interspersed with oil around the contact. Both of these effects lead to...24). [lhcse iments could be run with a thin film of hyvdrocarbon oil applied to were all basically unlubricated experiments that insol.t.d the sliding

  11. 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.

  12. Ultrastructural Analysis of Incinerated Teeth by Scanning Electron Microscope – A Short Study

    PubMed Central

    Swamy, Sugunakar Raju Godishala; Muddana, Keerthi

    2016-01-01

    Introduction In forensic context precise knowledge on physical and histological changes of teeth subjected to high temperatures is of great importance. Preserving fragile incinerated teeth for physical, histological and ultra structural examinations is essential in fire investigations involving the origin of fire, its cause as well as the identification of victims which relies on a thorough understanding of the structural changes in dental tissues subjected to heat. Aim The study was conducted to evaluate the physical and ultrastructural changes seen in freshly extracted teeth when subjected to gradual heating at different temperatures using Scanning Electron Microscope (SEM). Settings and Design Freshly extracted teeth collected from subjects of different age groups were subjected to different temperatures using laboratory furnace and findings were correlated to the temperature. Materials and Methods The study was conducted on 60 healthy freshly extracted teeth belonging to age group between 20-30 years. Group A comprised of control group which included teeth that were not subjected to heat whereas Group B, C and D comprised of teeth that were subjected to different temperatures i.e., 100oC, 300oC and 600oC respectively for a time of fifteen minutes in laboratory furnace, after which they were processed for SEM examination. Each group included 15 teeth; 5 anteriors, 5 premolars and 5 molars. Results Examination under SEM revealed definite ultra structural changes which were explicitly seen at particular temperatures (100oC, 300oC and 600oC). The samples showed cracks and charring of the tooth structure with ultra structural findings such as pebbles, granules, dots on enamel surface; and soap bubble pattern, honey comb pattern and snail track pattern on cementum surface. Conclusion Because of the consistency of morphological changes and the ultra structural patterns at various temperatures, evaluation of incinerated dental remains using SEM can provide additional

  13. Serotonin-producing cells in human gastric mucosa--immunohistochemical and electron microscopic study.

    PubMed

    Penkova, Nadya I; Baltadjiev, Georgi A; Koeva, Yvetta A; Atanassova, Pepa K; Andonov, Vladimir N; Trichkova, Valentina A

    2010-01-01

    The great many hormones released by the endocrine cells of the glands and lining epithelium of gastric mucosa determine its significance for the processes in the gastrointestinal tract. One of these hormones, serotonin, plays an important role in the regulation of the motility, secretion and sensation in the gastrointestinal tract. The aim of the present study was to conduct immunohistochemical and electron microscopic studies of serotonin-producing EC cell of gastric mucosa. Gastric mucosa biopsies were obtained and studied immunihistochemically for serotonin expression in the mucosa endocrine cells. Electron microscopic study was performed to specify the processes of synthesis, accumulation and release of secretory product by those cells. The immunohistochemical study revealed a considerable number of serotonin-containing EC cells scattered in the lining epithelium and between the glands in the corpus and pyloric region of the stomach. The electron microscopic study followed the stages of formation of the secretory granules from the initial accumulation of granular substance, its membrane packing and formation of mature granules to their disintegration in the secretory process. Serotonin as a neurotransmitter and gastrointestinal hormone appears to be a key to understanding a number of symptoms of gastrointestinal disorders like nausea, vomiting, pain, diarrhea and constipation. A detailed study of serotonin functions in the gastrointestinal tract realised through different types of receptors, and of the development of specific antagonists and agonists to these receptors would open up new opportunities for a more efficient treatment of gastrointestinal disorders.

  14. 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.

  15. Convenient preparation of high-quality specimens for annealing experiments in the transmission electron microscope.

    PubMed

    Duchamp, Martial; Xu, Qiang; Dunin-Borkowski, Rafal E

    2014-12-01

    A procedure based on focused ion beam milling and in situ lift-out is introduced for the preparation of high-quality specimens for in situ annealing experiments in the transmission electron microscope. The procedure allows an electron-transparent lamella to be cleaned directly on a heating chip using a low ion energy and back-side milling in order to minimize redeposition and damage. The approach is illustrated through the preparation of an Al-Mn-Fe complex metallic alloy specimen.

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

    SciTech Connect

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

    2011-06-01

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

  17. Enhanced microscopic nonlinear optical properties of novel Y-type chromophores with dual electron donor groups

    NASA Astrophysics Data System (ADS)

    Tang, Xiang; Pan, Lin; Jia, Kun; Tang, Xianzhong

    2016-03-01

    In this Letter, novel Y-type chromophores with dual electron donor groups, containing either styryl or azobenzene based π-conjugated bridge structures, were synthesized and their chemical structures, molecular configuration, microscopic optical properties as well as thermal properties were systematically characterized. The experimental results indicated that eight times increasing of second-order molecular hyperpolarizability as well as 50-100 nm blue shift of maximum absorption band for azobenzene based chromophore were observed by introducing Y-type dual electron donor groups, which was derived from the highly efficient 'total charge transfer' in this kind of chromophore as confirmed by the density functional theory calculation.

  18. Concurrent in situ ion irradiation transmission electron microscope

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  20. X-ray Energy Dispersive Spectrometry during in-situ Liquid Cell Studies using an Analytical Electron Microscope

    SciTech Connect

    Zaluzec, Nestor J.; Burke, M. Grace; Haigh, Sarah J.; Kulzick, Matthew

    2014-04-01

    The use of analytical spectroscopies during scanning/transmission electron microscope (S/TEM) investigations of micro- and nano-scale structures has become a routine technique in the arsenal of tools available to today's materials researchers. Essential to implementation and successful application of spectroscopy to characterization is the integration of numerous technologies, which include electron optics, specimen holders, and associated detectors. While this combination has been achieved in many instrument configurations, the integration of X-ray energy-dispersive spectroscopy and in situ liquid environmental cells in the S/TEM has to date been elusive. In this work we present the successful incorporation/modifications to a system that achieves this functionality for analytical electron microscopy.

  1. 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.

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

    SciTech Connect

    Zhang Haibo; Li Daoyu; Li Weiqin

    2007-12-15

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

  3. Irradiation-related amorphization and crystallization: In situ transmission electron microscope studies

    SciTech Connect

    Allen, C.W.

    1994-04-01

    Interfacing an ion accelerator to a transmission electron microscope (TEM) allows the analytical functions of TEM imaging and diffraction to be employed during ion-irradiation effects studies. At present there are twelve such installations in Japan, one in France and one in the US. This paper treats several aspects of in situ studies involving electron and ion beam induced and enhanced phase transformations and presents results of several in situ experiments to illustrate the dynamics of this approach in the materials science of irradiation effects. The paper describes the ion- and electron-induced amorphization of CuTi; the ion-irradiation-enhanced transformation of TiCr{sub 2}; and the ion- and electron-irradiation-enhanced crystallization of CoSi{sub 2}.

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

    SciTech Connect

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

    2016-08-15

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Characterization of Electron Microscopes with Binary Pseudo-random Multilayer Test Samples

    SciTech Connect

    V Yashchuk; R Conley; E Anderson; S Barber; N Bouet; W McKinney; P Takacs; D Voronov

    2011-12-31

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [1] and [2] and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [5]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi2/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  7. Characterization of electron microscopes with binary pseudo-random multilayer test samples

    SciTech Connect

    Yashchuk, V.V.; Conley, R.; Anderson, E.H.; Barber, S.K.; Bouet, N.; McKinney, W.R.; Takacs, P.Z. and Voronov, D.L.

    2010-12-08

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binarypseudo-random (BPR) gratings and arrays has been suggested and and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer. Here we describe the details of development of binarypseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi{sub 2}/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML testsamples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  8. Characterization of electron microscopes with binary pseudo-random multilayer test samples

    SciTech Connect

    Yashchuk, Valeriy V; Conley, Raymond; Anderson, Erik H; Barber, Samuel K; Bouet, Nathalie; McKinney, Wayne R; Takacs, Peter Z; Voronov, Dmitriy L

    2010-09-17

    Verification of the reliability of metrology data from high quality x-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [Proc. SPIE 7077-7 (2007), Opt. Eng. 47(7), 073602-1-5 (2008)} and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [Nucl. Instr. and Meth. A 616, 172-82 (2010)]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi2/Si multilayer coating with pseudo randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize x-ray microscopes. Corresponding work with x-ray microscopes is in progress.

  9. Electron microscopic observation of the sagittal structure of Drosophila mature sperm.

    PubMed

    Yasuno, Yusaku; Yamamoto, Masa-Toshi

    2014-09-01

    Observation of sperm development and determination of their morphological characteristics are very important to the understanding of phylogenetic relationships and the study of sperm function during fertilization. Although ultrastructural studies of sperm development in the testes of the fruit fly Drosophila have been performed, there are few reports describing electron microscopic morphology of mature sperm, that is, those released from the testes to the seminal vesicles. Here, we present the first report of the sagittal organization of Drosophila sperm head and neck regions by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The head and tail structures of a mature sperm, for example, the acrosome, nucleus, and flagellum, were easy to distinguish by the morphological characteristics of the sperm surface by SEM. The morphological relationships between the surface and internal structures of mature sperm were confirmed by observing longitudinal sections with TEM. Our approach overcame the technical difficulties involved in sample preparation for electron microscopic observation of the Drosophila mature sperm head, and therefore, this study serves as an important foundation for future genetic dissection of sperm ultrastructure and function in male sterile mutants.

  10. Non-Destructive Observations of Internal Micro-Defects Using Scanning Electron-Induced Acoustic Microscope

    NASA Astrophysics Data System (ADS)

    Koyama, Atsuhiro; Shibutani, Yoji

    Scanning electron-induced acoustic microscope (SEAM) has been developed as a new tool for non-destructive observations of the internal microstructures of materials. It consists of the electric chopper to pulse the high current electron beam and the detector of the longitudinal acoustic waves, both being attached to the commercial scanning electron microscope (SEM). The cyclic chopping of electron beam with extremely high frequency of a few hundred kilohertz makes the thermal wave due to the cyclic temperature rise with the short period. The wavelength of thermal wave may determine the essential SEAM resolution, because it's much smaller than the thermal stress wave (that is, the acoustic wave), which has just the role of conveying the information of thermal wave disturbance due to unexpected change as defects. Our own-built SEAM gives the best performance for observing the internal defects like the micro-voids, because it susceptibly senses the local difference of thermal properties in the sample. The paper indicates that some non-destructive observations for the micro-voids with a few microns order existing in the sintered materials are exhibited in conjunction with their destructive observations using focused-ion beam (FIB) technique to make certain of those as the proof.

  11. Spatially resolved quantum nano-optics of single photons using an electron microscope.

    PubMed

    Tizei, L H G; Kociak, M

    2013-04-12

    We report on the experimental demonstration of single-photon state generation and characterization in an electron microscope. In this aim we have used low intensity relativistic (energy between 60 and 100 keV) electrons beams focused in a ca. 1 nm probe to excite diamond nanoparticles. This triggered individual neutral nitrogen-vacancy centers to emit photons which could be gathered and sent to a Hanbury Brown-Twiss intensity interferometer. The detection of a dip in the correlation function at small time delays clearly demonstrates antibunching and thus the creation of nonclassical light states. Specifically, we have also demonstrated single-photon states detection. We unveil the mechanism behind quantum states generation in an electron microscope, and show that it clearly makes cathodoluminescence the nanometer scale analog of photoluminescence. By using an extremely small electron probe size and the ability to monitor its position with subnanometer resolution, we also show the possibility of measuring the quantum character of the emitted beam with deep subwavelength resolution.

  12. Microscopic investigation of the magnetic saturation process for Co/Pt multilayers

    NASA Astrophysics Data System (ADS)

    Quach, Duy-Truong; Kim, Dong-Hyun; Lee, Kyung-Min; Jeong, Jong-Ryul; Pham, Duc-Thang

    2016-07-01

    We have systematically investigated the magnetic saturation process for Co/Pt multilayers with perpendicular magnetic anisotropy by using the first-order reversal-curve (FORC) technique. We find that even for a field that apparently is higher than the major-loop saturation field, some microscopically not-yet-annihilated domains still remain. The true saturation on a microscopic scale field is found to be about 1.5 to 2.5 times greater than the macroscopicall-determined majorloop saturation field. Not-yet-annihilated domains are observed to be exponentially reduced with respect to the applied magnetic field.

  13. Application trials of in situ hybridization at the electron microscopic level.

    PubMed

    Kitazawa, Sohei; Kondo, Takeshi; Kitazawa, Riko

    2005-09-01

    In situ hybridization (ISH) is a morphology-oriented technique for demonstrating the presence of specific nucleic acid sequences at chromosomal, cytological and histological levels. It is, however, sometimes difficult to recognize specific cell identity, early phase mRNA expression and alternative splicing because of the limited resolution of the light microscope. To overcome this limitation, we developed an improved technique for ISH at the electron microscopic level, in which pre-embedding hybridization with a non-radioactively labeled probe was used, followed by post-embedding immunoglobulin gold colloid staining. By applying this technique, early phase bone morphogenetic protein-3 mRNA in the nuclei and cytoplasm was successfully demonstrated in a differentiating chondrocytic cell lineage. Moreover, with oligo-DNA probes specific for alternative spliced forms of parathyroid hormone-related protein mRNA, we demonstrated such forms in a hyperplastic parathyroid gland attributed to renal failure.

  14. Nonlinear least squares regression for single image scanning electron microscope signal-to-noise ratio estimation.

    PubMed

    Sim, K S; Norhisham, S

    2016-11-01

    A new method based on nonlinear least squares regression (NLLSR) is formulated to estimate signal-to-noise ratio (SNR) of scanning electron microscope (SEM) images. The estimation of SNR value based on NLLSR method is compared with the three existing methods of nearest neighbourhood, first-order interpolation and the combination of both nearest neighbourhood and first-order interpolation. Samples of SEM images with different textures, contrasts and edges were used to test the performance of NLLSR method in estimating the SNR values of the SEM images. It is shown that the NLLSR method is able to produce better estimation accuracy as compared to the other three existing methods. According to the SNR results obtained from the experiment, the NLLSR method is able to produce approximately less than 1% of SNR error difference as compared to the other three existing methods. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

  15. Light and electron microscopic evaluation of thymuses from feline leukemia virus-infected kittens.

    PubMed

    Pack, F D; Chapman, W L

    1980-01-01

    Light microscopic and electron microscopic findings in thymuses from 4-week old feline leukemia virus-infected and 4- and 9-week old noninfected kittens were evaluated and found to be morphologically similar to each other. Thymuses from 9-week old feline leukemia virusinfected kittens were markedly atrophied and individual lobules within each thymus varied in the severity of atrophy. Loubules having the least severe atrophy had a moderate thinning of the cortex and a heterogeneous thymuses included intense eosinopoiesis at the corticomedullary junction, increased prominence of vasculature, and enlarged Hassal's corpuscles. In addition to these changes lobules of thymus having the most severe atrophy had a marked cortical thymocyte depletion, lobule collapse, and increased numbers of mast cells. Degeneration of epithelial cells in most lobules was indicated by electronlucency of the cytoplasmic matrix and often greatly dilated rough endoplasmic reticulum.

  16. Osteogenesis imperfecta lethal in infancy: case report and scanning electron microscopic studies of the deciduous teeth.

    PubMed

    Levin, L S; Rosenbaum, K N; Brady, J M; Dorst, J P

    1982-12-01

    Radiologic evaluation of the skeleton and scanning electron microscopic studies of the teeth were performed on an infant boy with a lethal osteogenesis imperfecta (OI) syndrome who died at 10 mo of pneumonia. The skeletal findings included ribs that were focally expanded by fracture calluses, flat vertebral bodies, and wide limb bones. On fractured tooth surfaces, the enamel and dentin were normal as was the dentin calcification front. Although microscopic abnormalities have been noted in teeth from previously reported infants with lethal OI, a few studies also report infants with normal teeth. These differences in dental findings may indicate heterogeneity in OI lethal in infancy. Results of our study indicate that, until the primary biochemical defects in the OI syndromes are elucidated, examination of teeth from other infants with lethal OI and detailed evaluation of other clinical and skeletal features will aid in delineating heterogeneity and variation in expression in lethal OI.

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

    PubMed

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

    2016-11-01

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

  18. Microscopic Investigation of a New Two-Component Organic Conductor with Itinerant and Localized Spins: (CHTM-TTP)2TCNQ

    NASA Astrophysics Data System (ADS)

    Nakamura, Toshikazu; Taniguchi, Masateru; Misaki, Yohji; Tanaka, Kazuyoshi; Nogami, Yoshio

    2002-09-01

    Low-temperature electronic phases in a new two-component organic conductor, a segregated-stack charge-transfer salt called (CHTM-TTP)2TCNQ, are investigated. The ESR g tensor analyses indicate that there exist itinerant CHTM-TTP spins and localized TCNQ spins at R.T. The temperature dependence of the physical parameters reveals that this salt undergoes two drastic, successive phase transitions at low temperatures. The effective moment of the localized TCNQ spins decreases at the 245 K transition and completely disappears at the transition around 195 K. These curious physical properties are explained by the drastic changes in the electronic states of the two different types of spins. The spin susceptibility was decomposed into the contribution of each of the two spin species by using ESR, 1H-NMR, and static susceptibility analyses. We present a microscopic investigation of the two-spin system with itinerant and localized moments.

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

    PubMed

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

    2004-07-01

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

  20. An Aberration Corrected Photoemission Electron Microscope at the Advanced Light Source

    NASA Astrophysics Data System (ADS)

    Feng, J.; MacDowell, A. A.; Duarte, R.; Doran, A.; Forest, E.; Kelez, N.; Marcus, M.; Munson, D.; Padmore, H.; Petermann, K.; Raoux, S.; Robin, D.; Scholl, A.; Schlueter, R.; Schmid, P.; Stöhr, J.; Wan, W.; Wei, D. H.; Wu, Y.

    2004-05-01

    Design of a new aberration corrected Photoemission electron microscope PEEM3 at the Advanced Light Source is outlined. PEEM3 will be installed on an elliptically polarized undulator beamline and will be used for the study of complex materials at high spatial and spectral resolution. The critical components of PEEM3 are the electron mirror aberration corrector and aberration-free magnetic beam separator. The models to calculate the optical properties of the electron mirror are discussed. The goal of the PEEM3 project is to achieve the highest possible transmission of the system at resolutions comparable to our present PEEM2 system (50 nm) and to enable significantly higher resolution, albeit at the sacrifice of intensity. We have left open the possibility to add an energy filter at a later date, if it becomes necessary driven by scientific need to improve the resolution further.

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

    DOE PAGES

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

    2016-03-02

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

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

    SciTech Connect

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

    2016-03-02

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

  3. High-speed multiframe dynamic transmission electron microscope image acquisition system with arbitrary timing

    DOEpatents

    Reed, Bryan W.; DeHope, William J.; Huete, Glenn; LaGrange, Thomas B.; Shuttlesworth, Richard M.

    2015-10-20

    An electron microscope is disclosed which has a laser-driven photocathode and an arbitrary waveform generator (AWG) laser system ("laser"). The laser produces a train of temporally-shaped laser pulses of a predefined pulse duration and waveform, and directs the laser pulses to the laser-driven photocathode to produce a train of electron pulses. An image sensor is used along with a deflector subsystem. The deflector subsystem is arranged downstream of the target but upstream of the image sensor, and has two pairs of plates arranged perpendicular to one another. A control system controls the laser and a plurality of switching components synchronized with the laser, to independently control excitation of each one of the deflector plates. This allows each electron pulse to be directed to a different portion of the image sensor, as well as to be provided with an independently set duration and independently set inter-pulse spacings.

  4. High-speed multiframe dynamic transmission electron microscope image acquisition system with arbitrary timing

    DOEpatents

    Reed, Bryan W.; Dehope, William J; Huete, Glenn; LaGrange, Thomas B.; Shuttlesworth, Richard M

    2016-06-21

    An electron microscope is disclosed which has a laser-driven photocathode and an arbitrary waveform generator (AWG) laser system ("laser"). The laser produces a train of temporally-shaped laser pulses of a predefined pulse duration and waveform, and directs the laser pulses to the laser-driven photocathode to produce a train of electron pulses. An image sensor is used along with a deflector subsystem. The deflector subsystem is arranged downstream of the target but upstream of the image sensor, and has two pairs of plates arranged perpendicular to one another. A control system controls the laser and a plurality of switching components synchronized with the laser, to independently control excitation of each one of the deflector plates. This allows each electron pulse to be directed to a different portion of the image sensor, as well as to be provided with an independently set duration and independently set inter-pulse spacings.

  5. High-speed multi-frame dynamic transmission electron microscope image acquisition system with arbitrary timing

    SciTech Connect

    Reed, Bryan W.; DeHope, William J.; Huete, Glenn; LaGrange, Thomas B.; Shuttlesworth, Richard M.

    2016-02-23

    An electron microscope is disclosed which has a laser-driven photocathode and an arbitrary waveform generator (AWG) laser system ("laser"). The laser produces a train of temporally-shaped laser pulses each being of a programmable pulse duration, and directs the laser pulses to the laser-driven photocathode to produce a train of electron pulses. An image sensor is used along with a deflector subsystem. The deflector subsystem is arranged downstream of the target but upstream of the image sensor, and has a plurality of plates. A control system having a digital sequencer controls the laser and a plurality of switching components, synchronized with the laser, to independently control excitation of each one of the deflector plates. This allows each electron pulse to be directed to a different portion of the image sensor, as well as to enable programmable pulse durations and programmable inter-pulse spacings.

  6. Transmission electron microscopic method for gene mapping on polytene chromosomes by in situ hybridization.

    PubMed

    Wu, M; Davidson, N

    1981-11-01

    A transmission electron microscope method for gene mapping by in situ hybridization to Drosophila polytene chromosomes has been developed. As electron-opaque labels, we use colloidal gold spheres having a diameter of 25 nm. The spheres are coated with a layer of protein to which Escherichia coli single-stranded DNA is photochemically crosslinked. Poly(dT) tails are added to the 3' OH ends of these DNA strands, and poly(dA) tails are added to the 3' OH ends of a fragmented cloned Drosophila DNA. These probe--dA strands are hybridized in situ to polytene chromosome squashes. Gold spheres are linked to the hybridized probe--dA strands by A.T base pairing. The sphere positions relative to the chromosome bands can be observed by transmission electron microscopy. The method shows low background and high resolution.

  7. Proton Transmitting Energy Spectra and Transmission Electron Microscope Examinations of Biological Samples

    NASA Astrophysics Data System (ADS)

    Tan, Chun-yu; Xia, Yue-yuan; Zhang, Jian-hua; Mu, Yu-guang; Wang, Rui-jin; Liu, Ji-tian; Liu, Xiang-dong; Yu, Zeng-liang

    1999-02-01

    Transmission energy spectra of 530 keV H+ ion penetrating 140 μm thick seed coat of maize and fruit peel of grape with thickness of 100 μm were measured. The result indicates that these thick biological targets, as seen by the penetrating ions, are inhomogeneous, and there are open "channel like" paths along which the incident ions can transmit the targets easily. While most of the incident ions are stopped in the targets, some of the transmitting ions only lose a small fraction of their initial incident energy. The transmission energy spectra show a pure electronic stopping feature. Transmission electron microscope (TEM) micrographes taken from the samples of seed coat of maize and fruit peel of tomato with thickness of 60 μm indicate that 150 keV electron beam from the TEM can penetrate the thick samples to give very good images with clear contrasts.

  8. An aberration corrected photoemission electron microscope at the advanced light source

    SciTech Connect

    Feng, J.; MacDowell, A.A.; Duarte, R.; Doran, A.; Forest, E.; Kelez, N.; Marcus, M.; Munson, D.; Padmore, H.; Petermann, K.; Raoux, S.; Robin, D.; Scholl, A.; Schlueter, R.; Schmid, P.; Stohr, J.; Wan, W.; Wei, D.H.; Wu, Y.

    2003-11-01

    Design of a new aberration corrected Photoemission electron microscope PEEM3 at the Advanced Light Source is outlined. PEEM3 will be installed on an elliptically polarized undulator beamline and will be used for the study of complex materials at high spatial and spectral resolution. The critical components of PEEM3 are the electron mirror aberration corrector and aberration-free magnetic beam separator. The models to calculate the optical properties of the electron mirror are discussed. The goal of the PEEM3 project is to achieve the highest possible transmission of the system at resolutions comparable to our present PEEM2 system (50 nm) and to enable significantly higher resolution, albeit at the sacrifice of intensity. We have left open the possibility to add an energy filter at a later date, if it becomes necessary driven by scientific need to improve the resolution further.

  9. A review of transmission electron microscopes with in situ ion irradiation

    NASA Astrophysics Data System (ADS)

    Hinks, J. A.

    2009-12-01

    Transmission electron microscopy (TEM) with in situ ion irradiation is unique amongst experimental techniques in allowing the direct observation of the internal microstructure of materials on the nanoscale whilst they are being subjected to bombardment with energetic particles. Invaluable insights into the underlying atomistic processes at work can be gained through direct investigation of radiation induced and enhanced effects such as: phase changes and segregation; mechanical and structural changes; atomic/layer mixing and chemical disorder; compositional changes; chemical reactions; grain growth and shrinkage; precipitation and dissolution; defect/bubble formation, growth, motion, coalescence, removal and destruction; ionisation; diffusion; and collision cascades. The experimental results obtained can be used to validate the predictions of computational models which in turn can elucidate the mechanisms behind the phenomena seen in the microscope. It is 50 years since the first TEM observations of in situ ion irradiation were made by D.W. Pashley, A.E.B. Presland and J.W. Menter at the Tube Investment Laboratories in Cambridge, United Kingdom and 40 years since the first interfacing of an ion beam system with a TEM by P.A. Thackery, R.S. Nelson and H.C. Sansom at the Atomic Energy Research Establishment at Harwell, United Kingdom. In that time the field has grown with references in the literature to around thirty examples of such facilities. This paper gives an overview of the importance of the technique, especially with regard to the current challenges faced in understanding radiation damage in nuclear environments; a description of some of the important construction elements and design considerations of TEMs with in situ ion irradiation; a brief history of the development of this type of instrument; a summary of the facilities built around the world over the last half century; and finally a focus on the instruments in operation today.

  10. [Electron microscopic study of the intestinal epithelium of Saccoglossus mereschkowskii (Enteropneusta, Hemichordata)].

    PubMed

    Stoliarova, M V

    2011-01-01

    Epithelium of the hepatic region of the intestine in Saccoglossus mereschkowskii, a representative of enteropneusts (Enteropneusta, Hemichordata) standing at the base of Chordata, has been investigated using electron microscope. The ultrastructure of ciliated and granular epithelial cells, elements of the intraepithelial nerve layer, and intercellular junctions have been characterized. The data concerning details of the organization of the ciliary apparatus and rootlets system are presented. It is justified the presence of complicated supporting construction of cilia which performs a mechanical stabilizing function and possibly also provide synchronization of ciliary movements. The presence of cilia with two centrioles is considered as an adaptation to high functional load on ciliary apparatus. Well developed bundles of myofilaments are found in the cytoplasm of the basal portions of ciliary cells that characterizes these cells as myoepithelial. The features indicating the role of ciliary cells in absorption are described. The capability of these cells to balloon-like secretion is considered. Data on the accumulation of food reserves in the form of lipid droplets and glycogen in the cell cytoplasm are presented. Ciliated cells are characterized by their function as ciliated secretory-absorptive myoepithelial cells. Based on the location of secretory granules both in the apical and basal portions of granular cells, an exocrine-endocrine function of these cells has been suggested. Typical endocrine cells in the intestinal epithelium of S. mereschkowskii are absent. Several types of granules in the nerve fibers cytoplasm are described. Junctions between the nerve fibers and basal portions of ciliary and granular epithelial cells are found. Nerve regulation of contractile and secretory functions of epithelial cells is supposed. The presence of the regulatory nerve-endocrine system that includes receptor cells of open type, secretory endocrine-like cells and nerve

  11. ELECTRON MICROSCOPE OBSERVATIONS ON SYNAPTIC VESICLES IN SYNAPSES OF THE RETINAL RODS AND CONES

    PubMed Central

    De Robertis, Eduardo; Franchi, Carlos M.

    1956-01-01

    The submicroscopic organization of the rod and cone synapses of the albino rabbit has been investigated with the use of the electron microscope. The most common rod synapse consists of an enlarged expansion of the rod fiber (the so called spherule) into which the dendritic postsynaptic fiber of the bipolar cell penetrates and digitates. The membrane surrounding the terminal consists of a double layer, the external of which is interpreted as belonging to the intervening glial cells. The synaptic membrane has a pre- and a postsynaptic layer with a total thickness of 180 to 300 A. The presynaptic layer is frequently denser and is intimately associated with the adjacent synaptic vesicles. The synaptic membrane shows processes constituted by foldings of the presynaptic layer. The entire spherule is filled with synaptic vesicles varying in diameter between 200 and 650 A with a mean of 386 A. In addition, the spherule contains a few large vacuoles near the rod fiber, interpreted as endoplasmic reticulum, and a matrix in which with high resolution a fine filamentous material can be observed. The postsynaptic fiber is homogeneous and usually does not show synaptic vesicles. In animals maintained in complete darkness for 24 hours vesicles appear to accumulate near the synaptic membrane and its processes. After 9 days there is a sharp decrease in size of the synaptic vesicles. A special rod synapse in which the dendritic postsynaptic expansion penetrates directly into the rod cell body has been identified. In line with Cajal's classification this type of synapse could be considered as a somatodendritic one. The cone synapse has a much larger terminal with a more complex relationship with the postsynaptic fiber. However, the same components recognized in the rod synapse can be observed. In animals maintained for 9 days in complete darkness there is also a considerable diminution in size of the synaptic vesicles. PMID:13331963

  12. 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.

  13. 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.

  14. Image-based autonomous micromanipulation system for arrangement of spheres in a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Kasaya, Takeshi; Miyazaki, Hideki T.; Saito, Shigeki; Koyano, Koichi; Yamaura, Tomio; Sato, Tomomasa

    2004-06-01

    The micromanipulation technique in a scanning electron microscope (SEM) has been attracting interest as a technique to produce microstructures such as three-dimensional photonic crystals or advanced high-density electronic circuits. However, it is difficult to fabricate a large-scale structure or to conduct a systematic experiment using numbers of structures, as long as we rely on manually operated micromanipulation. In this study, we constructed an automatic system which arranges 10-μm-sized microspheres into a given two-dimensional pattern in a SEM. The spheres are picked up by touching with the center of the planar tip of a probe (needle), and placed on the substrate by moving the contact point to the edge of the tip and inclining the probe. The positions of the probe and the spheres are visually recognized from the SEM image from above and the optical microscope image from the side. The generalized Hough transform, which can robustly detect arbitrary shape from the edge fragments, is employed for the image recognition. Contact force information obtained by a force sensor with a resolution of 14 μN is also utilized for the control. Completely automatic rearrangement of randomly sprinkled metal spheres with a diameter of 30 μm into arbitrary patterns was successfully demonstrated. Autonomous micromanipulation technique under the observation of a SEM would contribute not merely to laboratories but also to the opto-electronics industry.

  15. In vitro phagocytosis of exogenous collagen by fibroblasts from the periodontal ligament: an electron microscopic study.

    PubMed Central

    Svoboda, E L; Brunette, D M; Melcher, A H

    1979-01-01

    There have been numerous electron microscopic reports of apparent phagocytosis of collagen by fibroblasts and other cells in vivo. We have developed an in vitro system which, to the best of our knowledge, will permit for the first time the study of regulatory mechanisms governing phagocytosis and digestion of collagen fibres. Cells were cultured from explants of monkey periodontal ligament, subcultured, and grown to confluence in alpha-MEM plus 15% fetal calf serum plus antibiotics. The confluent cells were then cultured together with minced rat tail tendon collagen in alpha-MEM lacking proline, lysine, glycine and fetal calf serum for up to 7 days, after which they were processed for electron microscopy. Intracellular collagen profiles could be seen in cultured cells that were associated with exogenous collagen fibrils as early as 24 hours after addition of the collagen. Through electron microscopic examination of serial sections of the culture, we have demonstrated: (1) that fibroblasts can phagocytose collagen; (2) that the observed intracellular collagen is not the result of aggregation of endogenous synthesized collagen; (3) that it is not possible to base a decision as to whether a collagen fibril has been phagocytosed in whole or in part by the type of vesicle with which it is associated; (4) that cleavage of collagen into small pieces may not be a necessary prelude to its phagocytosis. Images Fig. 1 Fig. 2 Fig. 4 (cont.) Fig. 4 Fig. 6 (cont.) Fig. 6 Fig. 7 Fig. 8 Fig. 9 PMID:108237

  16. Electron microscopic study of soot particulate matter emissions from aircraft turbine engines.

    PubMed

    Liati, Anthi; Brem, Benjamin T; Durdina, Lukas; Vögtli, Melanie; Dasilva, Yadira Arroyo Rojas; Eggenschwiler, Panayotis Dimopoulos; Wang, Jing

    2014-09-16

    The microscopic characteristics of soot particulate matter (PM) in gas turbine exhaust are critical for an accurate assessment of the potential impacts of the aviation industry on the environment and human health. The morphology and internal structure of soot particles emitted from a CFM 56-7B26/3 turbofan engine were analyzed in an electron microscopic study, down to the nanoscale, for ∼ 100%, ∼ 65%, and ∼ 7% static engine thrust as a proxy for takeoff, cruising, and taxiing, respectively. Sampling was performed directly on transmission electron microscopy (TEM) grids with a state-of-the-art sampling system designed for nonvolatile particulate matter. The electron microscopy results reveal that ∼ 100% thrust produces the highest amount of soot, the highest soot particle volume, and the largest and most crystalline primary soot particles with the lowest oxidative reactivity. The opposite is the case for soot produced during taxiing, where primary soot particles are smallest and most reactive and the soot amount and volume are lowest. The microscopic characteristics of cruising condition soot resemble the ones of the ∼ 100% thrust conditions, but they are more moderate. Real time online measurements of number and mass concentration show also a clear correlation with engine thrust level, comparable with the TEM study. The results of the present work, in particular the small size of primary soot particles present in the exhaust (modes of 24, 20, and 13 nm in diameter for ∼ 100%, ∼ 65% and ∼ 7% engine thrust, respectively) could be a concern for human health and the environment and merit further study. This work further emphasizes the significance of the detailed morphological characteristics of soot for assessing environmental impacts.

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

    SciTech Connect

    Ishii, Yoshiyuki

    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 for 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.

  18. Magnetic lens apparatus for a low-voltage high-resolution electron microscope

    DOEpatents

    Crewe, Albert V.

    1996-01-01

    A lens apparatus in which a beam of charged particles of low accelerating voltage is brought to a focus by a magnetic field, the lens being situated behind the target position. The lens comprises an electrically-conducting coil arranged around the axis of the beam and a magnetic pole piece extending along the axis of the beam at least within the space surrounded by the coil. The lens apparatus comprises the sole focusing lens for high-resolution imaging in a low-voltage scanning electron microscope.

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

    NASA Technical Reports Server (NTRS)

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

    2017-01-01

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

  20. A practical method for the remote control of the scanning electron microscope.

    PubMed

    Yamada, Atsushi; Hirahara, Osamu; Tsuchida, Takayoshi; Sugano, Naoki; Date, Masaru

    2003-01-01

    We have developed a remote control system for the scanning electron microscope (SEM). It is called Web-SEM and can be accessed by anyone through the Web browser. It is not necessary to install special software to control the SEM. Because the operating performance changes with the amount of traffic on the Internet, we have connected the Web-SEM to a LAN/Internet in order to overcome this. We have checked the performance of the remote control operation and we were able to perform focus adjustment, stage movement, etc. over the Internet by improving the method of operation and image transfer.

  1. Interpretation of scanning electron microscope measurements of minority carrier diffusion lengths in semiconductors

    NASA Technical Reports Server (NTRS)

    Flat, A.; Milnes, A. G.

    1978-01-01

    In scanning electron microscope (SEM) injection measurements of minority carrier diffusion lengths some uncertainties of interpretation exist when the response current is nonlinear with distance. This is significant in epitaxial layers where the layer thickness is not large in relation to the diffusion length, and where there are large surface recombination velocities on the incident and contact surfaces. An image method of analysis is presented for such specimens. A method of using the results to correct the observed response in a simple convenient way is presented. The technique is illustrated with reference to measurements in epitaxial layers of GaAs. Average beam penetration depth may also be estimated from the curve shape.

  2. Scanning-electron-microscope study of normal-impingement erosion of ductile metals

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Salik, J.

    1980-01-01

    Scanning electron microscopy was used to characterize the erosion of annealed copper and aluminum surfaces produced by both single- and multiple-particle impacts. Macroscopic 3.2 mm diameter steel balls and microscopic, brittle erodant particles were projected by a gas gun system so as to impact at normal incidence at speeds up to 140 m/sec. During the impacts by the brittle erodant particles, at lower speeds the erosion behavior was similar to that observed for the larger steel balls. At higher velocities, particle fragmentation and the subsequent cutting by the radial wash of debris created a marked change in the erosion mechanism.

  3. A low temperature scanning tunneling microscope for electronic and force spectroscopy.

    PubMed

    Smit, R H M; Grande, R; Lasanta, B; Riquelme, J J; Rubio-Bollinger, G; Agraït, N

    2007-11-01

    In this article, we describe and test a novel way to extend a low temperature scanning tunneling microscope with the capability to measure forces. The tuning fork that we use for this is optimized to have a high quality factor and frequency resolution. Moreover, as this technique is fully compatible with the use of bulk tips, it is possible to combine the force measurements with the use of superconductive or magnetic tips, advantageous for electronic spectroscopy. It also allows us to calibrate both the amplitude and the spring constant of the tuning fork easily, in situ and with high precision.

  4. Reducing scanning electron microscope charging by using exponential contrast stretching technique on post-processing images.

    PubMed

    Sim, K S; Tan, Y Y; Lai, M A; Tso, C P; Lim, W K

    2010-04-01

    An exponential contrast stretching (ECS) technique is developed to reduce the charging effects on scanning electron microscope images. Compared to some of the conventional histogram equalization methods, such as bi-histogram equalization and recursive mean-separate histogram equalization, the proposed ECS method yields better image compensation. Diode sample chips with insulating and conductive surfaces are used as test samples to evaluate the efficiency of the developed algorithm. The algorithm is implemented in software with a frame grabber card, forming the front-end video capture element.

  5. PROTEIN SYNTHESIS IN THE VISUAL CELLS OF THE HONEYBEE DRONE AS STUDIED WITH ELECTRON MICROSCOPE RADIOAUTOGRAPHY

    PubMed Central

    Perrelet, Alain

    1972-01-01

    Protein synthesis was studied in the visual cells of an insect (honeybee drone, Apis mellifera) by electron microscope radioautography. After a single injection of tritiated leucine, the radioactivity first appears in the cytoplasm of the visual cell which contains ribosomes. Later, part of this radioactivity migrates to the rhabdome, the visual cell region which is specialized in light absorption. A maximal concentration of radioactivity is reached there 48 hr after the injection of leucine. This pattern of protein synthesis and transport resembles that described in vertebrate visual cells (rods and cones), where newly synthesized proteins have been shown to contribute to the renewal of the photoreceptor membrane. PMID:4656703

  6. 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.

  7. Scanning electron microscope studies of Agrobacterium tumefaciens attachment to Zea mays, Gladiolus sp., and Triticum aestivum.

    PubMed Central

    Graves, A E; Goldman, S L; Banks, S W; Graves, A C

    1988-01-01

    Scanning electron microscope studies demonstrated that cells of Agrobacterium tumefaciens strains attach to cells on the cut surfaces of corn and wheat seedlings and to gladiolus disks. Bacterial cells attached to these monocots in the same manner as they attached to the dicots tested. Of the strains tested, A66 and T37 covered more of the cut surfaces of these monocots in a nonrandom fashion than did cells of other isolates. These bacteria attached to cells of intact monocotyledonous plants and had the greatest affinity for tissues located within the vascular bundles. They attached in large numbers to cells in these areas in all three monocots tested. Images PMID:3360748

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

    NASA Technical Reports Server (NTRS)

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

    2017-01-01

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

  9. An investigation into vascular prosthesis modified with an electron beam.

    PubMed

    Lowkis, B; Szymonowicz, M; Rutkowski, J

    1997-01-01

    The present paper shows the results of an investigation into the effect of implanted electric charge on blood platelet adhesion to woven surfaces of "Dallon" polyester vascular prosthesis. The electrets were formed using the electron beam method. The assessment of the electret effect on blood platelet adhesion was performed on the basis of microscopic studies. It was shown that an implanted negative electric charge remarkably suppresses thrombocyte adhesion to the prosthesis surface. The electret effect was found to play a significant role in the process of preparing nonthrombogenic surfaces.

  10. Coherence of a spin-polarized electron beam emitted from a semiconductor photocathode in a transmission electron microscope

    SciTech Connect

    Kuwahara, Makoto Saitoh, Koh; Tanaka, Nobuo; Kusunoki, Soichiro; Nambo, Yoshito; Ujihara, Toru; Asano, Hidefumi; Jin, Xiuguang; Takeda, Yoshikazu

    2014-11-10

    The brightness and interference fringes of a spin-polarized electron beam extracted from a semiconductor photocathode excited by laser irradiation are directly measured via its use in a transmission electron microscope. The brightness was 3.8 × 10{sup 7 }A cm{sup −2 }sr{sup −1} for a 30-keV beam energy with the polarization of 82%, which corresponds to 3.1 × 10{sup 8 }A cm{sup −2 }sr{sup −1} for a 200-keV beam energy. The resulting electron beam exhibited a long coherence length at the specimen position due to the high parallelism of (1.7 ± 0.3) × 10{sup −5 }rad, which generated interference fringes representative of a first-order correlation using an electron biprism. The beam also had a high degeneracy of electron wavepacket of 4 × 10{sup −6}. Due to the high polarization, the high degeneracy and the long coherence length, the spin-polarized electron beam can enhance the antibunching effect.

  11. Atmospheric scanning electron microscope system with an open sample chamber: configuration and applications.

    PubMed

    Nishiyama, Hidetoshi; Koizumi, Mitsuru; Ogawa, Koji; Kitamura, Shinich; Konyuba, Yuji; Watanabe, Yoshiyuki; Ohbayashi, Norihiko; Fukuda, Mitsunori; Suga, Mitsuo; Sato, Chikara

    2014-12-01

    An atmospheric scanning electron microscope (ASEM) with an open sample chamber and optical microscope (OM) is described and recent developments are reported. In this ClairScope system, the base of the open sample dish is sealed to the top of the inverted SEM column, allowing the liquid-immersed sample to be observed by OM from above and by SEM from below. The optical axes of the two microscopes are aligned, ensuring that the same sample areas are imaged to realize quasi-simultaneous correlative microscopy in solution. For example, the cathodoluminescence of ZnO particles was directly demonstrated. The improved system has (i) a fully motorized sample stage, (ii) a column protection system in the case of accidental window breakage, and (iii) an OM/SEM operation system controlled by a graphical user interface. The open sample chamber allows the external administration of reagents during sample observation. We monitored the influence of added NaCl on the random motion of silica particles in liquid. Further, using fluorescence as a transfection marker, the effect of small interfering RNA-mediated knockdown of endogenous Varp on Tyrp1 trafficking in melanocytes was examined. A temperature-regulated titanium ASEM dish allowed the dynamic observation of colloidal silver nanoparticles as they were heated to 240°C and sintered.

  12. Light and Electron Microscopic Changes in the Myocardium of Influenza-Infected Turkeys

    PubMed Central

    McKenzie, Basil E.; Easterday, Bernard C.; Will, James A.

    1972-01-01

    Virus isolation and titration, electrocardiography, enzyme assays and light and electron microscopic studies were undertaken in male turkeys infected with influenza A/turkey/Ontario/7732/66 virus to determine its potential role in the genesis of heart disease. Virus was isolated from the heart initially before a demonstrable viremia and terminally in declining serum viral titer. Virus was isolated from the heart muscle as early as 1 day postinoculation. Highest viral titers were found in the heart at 6 days postinoculation and coincided with maximum elevations of serum glutamic-oxalacetic transaminase and lactic acid dehydrogenase, microscopic lesions in the heart and cardiac arrhythmias. Microscopic lesions in the heart were first detected at 4 days postinoculation and consisted of disseminated areas of necrosis, focal myocarditis, pericarditis and endocarditis. Alterations in myocardial ultrastructure which followed viral infection included fragmentation and dissolution of myofibrils, dilation of the sarcotubular system, increase in membrane vesicle formation in the region of the endoplasmic reticulum, discontinuity of the sarcolemma, proliferation of mitochondrial population, swelling of mitochondria with separation and disruption of the cristae, and the presence of intramitochondrial and perinuclear densities. ImagesFig 1Fig 2Fig 3Fig 4Fig 5Fig 6Fig 7 PMID:4634735

  13. Computer control of a scanning electron microscope for digital image processing of thermal-wave images

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    Using a recently developed technology called thermal-wave microscopy, NASA Lewis Research Center has developed a computer controlled submicron thermal-wave microscope for the purpose of investigating III-V compound semiconductor devices and materials. This paper describes the system's design and configuration and discusses the hardware and software capabilities. Knowledge of the Concurrent 3200 series computers is needed for a complete understanding of the material presented. However, concepts and procedures are of general interest.

  14. Putting structure into context: fitting of atomic models into electron microscopic and electron tomographic reconstructions.

    PubMed

    Volkmann, Niels

    2012-02-01

    A complete understanding of complex dynamic cellular processes such as cell migration or cell adhesion requires the integration of atomic level structural information into the larger cellular context. While direct atomic-level information at the cellular level remains inaccessible, electron microscopy, electron tomography and their associated computational image processing approaches have now matured to a point where sub-cellular structures can be imaged in three dimensions at the nanometer scale. Atomic-resolution information obtained by other means can be combined with this data to obtain three-dimensional models of large macromolecular assemblies in their cellular context. This article summarizes some recent advances in this field. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Fundamental and experimental aspects of diffraction for characterizing dislocations by electron channeling contrast imaging in scanning electron microscope.

    PubMed

    Kriaa, H; Guitton, A; Maloufi, N

    2017-08-29

    Nowadays Field Emission Gun-Scanning Electron Microscopes provide detailed crystallographic information with high spatial and angular resolutions, and allow direct observation of crystalline defects, such as dislocations, through an attractive technique called Electron Channeling Contrast Imaging (ECCI). Dislocations play a crucial role in the properties of materials and ECCI has naturally emerged as an adapted tool for characterizing defects in bulk specimen. Nevertheless, fine control of the channeling conditions is absolutely required to get strong dislocation contrast for achieving comprehensive analysis. In this work, experiment-assisted fundamental aspects of the origin of dislocation contrast are studied. Experimentally, the potential of ECCI is explored in several dislocation configurations in Interstitial-Free steel (Fe - 1% Si) used as a model material. Full interpretations of dislocation contrast in (g, -g) and its evolution along the Kikuchi band are shown. Furthermore, a dislocation dipole is observed and fully characterized for the first time in an SEM.

  16. Charging/discharge events in coated spacecraft polymers during electron beam irradiation in a scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Czeremuszkin, G.; Latrèche, M.; Wertheimer, M. R.

    2001-12-01

    Spacecraft, such as those operating in geosynchronous orbit (GEO), can be subjected to intense irradiation by charged particles, for example high-energy (e.g. 20 keV) electrons. The surfaces of dielectric materials (for example, polymers used as "thermal blankets") can therefore become potential sites for damaging electrostatic discharge (ESD) pulse events. We simulate these conditions by examining small specimens of three relevant polymers (polyimide, polyester and fluoropolymer), both bare and coated, in a scanning electron microscope (SEM). The coatings examined include commercial indium-tin oxide (ITO), and thin films of SiO 2 and a-Si:H deposited by plasma-enhanced chemical vapor deposition (PECVD). All coatings are found to greatly modify the observed ESD behavior, compared with that of the bare polymer counterparts. These observations are explained in terms of the model for ESD pulses proposed by Frederickson.

  17. Electron microscope tomography: further demonstration of nanocontacts between caveolae and smooth muscle sarcoplasmic reticulum

    PubMed Central

    Gherghiceanu, Mihaela; Popescu, LM

    2007-01-01

    Abstract A spatial relationship between caveolae and sarcoplasmic reticulum (SR) in smooth muscle cells (SMC) was previously reported in computer-assisted three-dimensional reconstruction from transmission electron microscope serial sections. The knowledge of the three-dimensional organization of the cortical space of SMC is essential to understand caveolae function at the cellular level. Cellular tomography using transmission electron microscopy tomography (EMT) is the only available technology to reliably chart the inside of a cell and is therefore an essential technology in the study of organellar nanospatial relationships. Using EMT we further demonstrate here that caveolae and peripheral SR in visceral SMC build constantly spatial units, presumably responsible for a vectorial control of free Ca2+ cytoplasmic concentrations in definite nanospaces. PMID:18205711

  18. 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.

  19. Image transfer with spatial coherence for aberration corrected transmission electron microscopes.

    PubMed

    Hosokawa, Fumio; Sawada, Hidetaka; Shinkawa, Takao; Sannomiya, Takumi

    2016-08-01

    The formula of spatial coherence involving an aberration up to six-fold astigmatism is derived for aberration-corrected transmission electron microscopy. Transfer functions for linear imaging are calculated using the newly derived formula with several residual aberrations. Depending on the symmetry and origin of an aberration, the calculated transfer function shows characteristic symmetries. The aberrations that originate from the field's components, having uniformity along the z direction, namely, the n-fold astigmatism, show rotational symmetric damping of the coherence. The aberrations that originate from the field's derivatives with respect to z, such as coma, star, and three lobe, show non-rotational symmetric damping. It is confirmed that the odd-symmetric wave aberrations have influences on the attenuation of an image via spatial coherence. Examples of image simulations of haemoglobin and Si [211] are shown by using the spatial coherence for an aberration-corrected electron microscope.

  20. A scanning electron microscope examination of silver cones removed from endodontically treated teeth. 1972.

    PubMed

    Seltzer, Samuel; Green, Daniel B; Weiner, Neil; DeRenzis, Frank

    2004-07-01

    Twenty-five silver cones were removed from teeth which had been treated endodontically from 3 months to 20 years previously. Examination by the scanning electron microscope revealed that these cones were moderately to severely corroded. The corrosion patterns were described as ranging from pitting to deep crater formation with globular or spherical agglomerations. Examinations with the electron probe showed sulfur peaks on the corroded portions of the cones. X-ray diffraction analyses indicated that the chemical compounds formed were silver sulfides, silver sulfates, silver carbonates, and silver amine sulfate amide hydrates. Tissue culture studies indicated that the corrosion products were highly cytotoxic. The mechanisms for the formation of the corrosion products have been postulated as being due to plastic deformations and metal transfer to the silver cones, plus contact of the silver with tissue fluids.